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Posts Tagged ‘B-cell cancers’


Immunopathogenesis Advances in Diabetes and Lymphomas

Larry H Bernstein, MD, FCAP, Curator

LPBI

 

 

 Science team says they’ve taken another step toward a potential cure for diabetes

Wednesday, January 27, 2016 | By John Carroll
Building on years of work on developing new insulin-producing cells that could one day control glucose levels and cure diabetes, a group of investigators led by scientists at MIT and Boston Children’s Hospital say they’ve developed a promising new gel capsule that protected the cells from an immune system assault.

Dr. Jose Oberholzer, a professor of bioengineering at the University of Illinois at Chicago, tested a variety of chemically modified alginate hydrogel spheres to see which ones would be best at protecting the islet cells created from human stem cells.

The team concluded that 1.5-millimeter spheres of triazole-thiomorphine dioxide (TMTD) alginate were best at protecting the cells and allowing insulin to seep out without spurring an errant immune system attack or the development of scar tissue–two key threats to making this work in humans.

They maintained healthy glucose levels in the rodents for 174 days, the equivalent to decades for humans.

“While this is a very promising step towards an eventual cure for diabetes, a lot more testing is needed to ensure that the islet cells don’t de-differentiate back toward their stem-cell states or become cancerous,” said Oberholzer.

Millions of diabetics have effectively controlled the chronic disease with existing therapies, but there’s still a huge unmet medical need to consider. While diabetes companies like Novo ($NVO) like to cite the fact that a third of diabetics have the disease under control, a third are on meds but don’t control it well and a third haven’t been diagnosed. An actual cure for the disease, which has been growing by leaps and bounds all over the world, would be revolutionary.

Their study was published in Nature Medicine.

– here’s the release
– get the journal abstract

 

Long-term glycemic control using polymer-encapsulated human stem cell–derived beta cells in immune-competent mice

Arturo J Vegas, Omid Veiseh, Mads Gürtler,…, Robert Langer & Daniel G Anderson

Nature Medicine (2016)   http://dx.doi.org:/10.1038/nm.4030

The transplantation of glucose-responsive, insulin-producing cells offers the potential for restoring glycemic control in individuals with diabetes1. Pancreas transplantation and the infusion of cadaveric islets are currently implemented clinically2, but these approaches are limited by the adverse effects of immunosuppressive therapy over the lifetime of the recipient and the limited supply of donor tissue3. The latter concern may be addressed by recently described glucose-responsive mature beta cells that are derived from human embryonic stem cells (referred to as SC-β cells), which may represent an unlimited source of human cells for pancreas replacement therapy4. Strategies to address the immunosuppression concerns include immunoisolation of insulin-producing cells with porous biomaterials that function as an immune barrier56. However, clinical implementation has been challenging because of host immune responses to the implant materials7. Here we report the first long-term glycemic correction of a diabetic, immunocompetent animal model using human SC-β cells. SC-β cells were encapsulated with alginate derivatives capable of mitigating foreign-body responses in vivo and implanted into the intraperitoneal space of C57BL/6J mice treated with streptozotocin, which is an animal model for chemically induced type 1 diabetes. These implants induced glycemic correction without any immunosuppression until their removal at 174 d after implantation. Human C-peptide concentrations and in vivo glucose responsiveness demonstrated therapeutically relevant glycemic control. Implants retrieved after 174 d contained viable insulin-producing cells.

Subject terms: Regenerative medicine  Type 1 diabetes

Figure 1: SC-β cells encapsulated with TMTD alginate sustain normoglycemia in STZ-treated immune-competent C57BL/6J mice.close

(a) Top, schematic representation of the last three stages of differentiation of human embryonic stem cells to SC-β cells. Stage 4 cells (pancreatic progenitors 2) co-express pancreatic and duodenal homeobox 1 (PDX-1) and NK6 homeobox 1…

 

Potential Cure for Diabetes Discovered  
http://www.rdmag.com/news/2016/01/potential-cure-diabetes-discovered   01/27/2016

Two new scientific papers published on Monday demonstrated tools that could result in potential therapies for patients diagnosed with type 1 diabetes, a condition in which the immune system limits the production of insulin, typically in adolescents.  See —

Bubble Technique Could Create Type 1 Diabetes Therapy

http://www.dddmag.com/news/2016/01/bubble-technique-could-create-type-1-diabetes-therapy

Two new scientific papers published on Monday demonstrated tools that could result in potential therapies for patients diagnosed with type 1 diabetes, a condition in which the immune system limits the production of insulin, typically in adolescents.

Previous treatments for this disease have involved injecting beta cells from dead donors into patients to help their pancreas generate healthy-insulin cells, writes STAT. However, this method has resulted in the immune system targeting these new cells as “foreign” so transplant recipients have had to take immune-suppressing medications for the rest of their lives.

The first paper published in the journal Nature Biotechnology explained how scientists analyzed a seaweed extract called alginate to gauge its effectiveness in supporting the flow of sugar and insulin between cells and the body. An estimated 774 variations were tested in mice and monkeys in which results indicated only a handful could reduce the body’s response to foreign invaders, explains STAT.

The other paper in the journal Nature Medicine detailed a process where scientists developed small capsules infused with alginate and embryonic stem cells. A six-month observation period revealed this “protective bubble” technique “began to produce insulin in response to blood glucose levels” after transplantation in mice subjects with a condition similar to type 1 diabetes, reports Gizmodo.

Essentially, this cured the mice of their diabetes, and the beta cells worked as well as the body’s own cells, according to the researchers. Human trials could still be a few years away, but this experiment could yield a safer alternative to insulin injections.

 

Combinatorial hydrogel library enables identification of materials that mitigate the foreign body response in primates

Arturo J Vegas, Omid Veiseh, Joshua C Doloff, et al.

Nature Biotechnology (2016)    http://dx.doi.org:/10.1038/nbt.3462

The foreign body response is an immune-mediated reaction that can lead to the failure of implanted medical devices and discomfort for the recipient1, 2, 3, 4, 5, 6. There is a critical need for biomaterials that overcome this key challenge in the development of medical devices. Here we use a combinatorial approach for covalent chemical modification to generate a large library of variants of one of the most widely used hydrogel biomaterials, alginate. We evaluated the materials in vivo and identified three triazole-containing analogs that substantially reduce foreign body reactions in both rodents and, for at least 6 months, in non-human primates. The distribution of the triazole modification creates a unique hydrogel surface that inhibits recognition by macrophages and fibrous deposition. In addition to the utility of the compounds reported here, our approach may enable the discovery of other materials that mitigate the foreign body response.

 

Video 1: Intravital imaging of 300 μm SLG20 microcapsules.

Video 2: Intravital imaging of 300 μm Z2-Y12 microcapsules.

Video 3: NHP Laparoscopic procedure for the retrieval of Z2-Y12 spheres.

 

Clinical Focus on Follicular Lymphoma: CAR T-Cells Active in Relapsed Blood Cancers

MedPage Today

CAR T-Cells Active in Relapsed Blood Cancers

Complete responses in half of patients

by Charles Bankhead

Patients with relapsed and refractory B-cell malignancies have responded to treatment with modified T-cells added to conventional chemotherapy, data from an ongoing Swedish study showed.

Six of the first 11 evaluable patients achieved complete responses with increasing doses of chimeric antigen receptor (CAR)-modified T-cells that target the CD19 antigen, although two subsequently relapsed.

Five of the six responding patients received preconditioning chemotherapy the day before CAR T-cell infusion, in addition to chemotherapy administered up to 90 days before T-cell infusion to reduce tumor-cell burden. The remaining five patients received only the earlier chemotherapy, according to a presentation at the inaugural International Cancer Immunotherapy Conference in New York City.

“The complete responses in lymphoma patients despite the fact that they received only low doses of preconditioning compared with other published data surprised us,” Angelica Loskog, PhD, of Uppsala University in Sweden, said in a statement. “The strategy of both providing tumor-reductive chemotherapy for weeks prior to CAR T-cell infusion combined with preconditioning just before CAR T-cell infusion seems to offer promise.

CAR T-cells have demonstrated activity in a variety of studies involving patients with B-cell malignancies. Much of the work has focused on patients with leukemia, including trials in the U.S. B-cell lymphomas have proven more difficult to treat with CAR T-cells because the diseases are associated with higher concentration of immunosuppressive cells that can inhibit CAR T-cell activity, said Loskog. Moreover, blood-vessel abnormalities and accumulation of fibrotic tissue can hinder tumor penetration by therapeutic T-cells.

Each laboratory has its own process for modifying T-cells. Loskog and colleagues in Sweden and at Baylor College of Medicine in Houston have developed third-generation CAR T-cells that contain signaling domains for CD28 and 4-1BB, which act as co-stimulatory molecules. In preclinical models, third-generation CAR T-cells have demonstrated increased activation and proliferation in response to antigen challenge. Additionally, they have chosen to experiment with tumor burden-reducing chemotherapy, a preconditioning chemotherapy to counter the higher immunosuppressive cell count in lymphoma patients.

Loskog reported details of an ongoing phase I/IIa clinical trial involving patients with relapsed or refractory CD19-positive B-cell malignancies. Altogether, investigators have treated 12 patients with increasing doses (2 x 107 to 2 x 108 cells/m2) of CAR T-cells. One patient (with mixed follicular/Burkitt lymphoma) has yet to be evaluated for response. The remaining 11 included three patients with diffuse large B-cell lymphoma (DLBCL), one with follicular lymphoma transformed to DLBCL, two with chronic lymphocytic leukemia, two with mantle cell lymphoma, and three with acute lymphoblastic leukemia.

All of the patients with lymphoma received standard tumor cell-reducing chemotherapy, beginning 3 to 90 days before administration of CAR T-cells. Beginning with the sixth patient in the cohort, patients also received preconditioning chemotherapy (cyclophosphamide/fludarabine) 1 to 2 days before T-cell infusion to reduce the number and activity of immunosuppressive cells.

Cytokine release syndrome is a common effect of CAR T-cell therapy and occurred in several patients treated. In general, the syndrome has been manageable and has not interfered with treatment or response to the modified T-cells.

On the basis of the data produced thus far, the investigators have proceeded with patient evaluation and enrollment. They have already begun cell production for the next patient that will be treated with autologous CAR T-cells.

Although laboratories have their own cell production techniques, the treatment strategy has broad applicability to the treatment of B-cell malignancies, said Loskog.

“The results using different CARs and different techniques for manufacturing them is very similar in the clinic, in terms of initial complete response,” she told MedPage Today. “By using 4-1BB as a co-stimulator in the CAR intracellular region, it seems possible to achieve long-term complete responses in some patients. However, preconditioning of the patients with chemotherapy to reduce the regulatory immune cells seems crucial for effect.”

In an effort to manage the effect of patients’ immunosuppressive cells, the investigators have begun studying each the immune profile before and after treatment. Preliminary results suggest that the population of immunosuppressive cells increases over time, which has the potential to interfere with CAR T-cell responses.

“Especially for lymphoma, it may be crucial to deplete such cells prior to CAR infusion,” said Loskog. “It may even be necessary with supportive treatment for some time after CAR T-cell infusion. A supportive treatment needs to specifically regulate the suppressive cells while sparing the effect of CARs.”

The immunotherapy conference is jointly sponsored by the American Association for Cancer Research, the Cancer Research Institute, the Association for Cancer Immunotherapy, and the European Academy of Tumor Immunology.

 

PET-CT Best for FL Response Assessment

PET-CT associated with better progression-free and overall survival rates in follicular lymphoma.

Kay Jackson

PET-CT (PET) rather than contrast-enhanced CT scanning should be considered the new gold standard for response assessment after first-line rituximab therapy for high-tumor burden follicular lymphoma (FL), a pooled analysis of a central review in three multicenter studies indicated.

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Liposomes, Lipidomics and Metabolism

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

Building a Better Liposome

Computational models suggest new design for nanoparticles used in targeted drug delivery.

http://www.technologynetworks.com/Metabolomics/news.aspx?ID=184147

Using computational modeling, researchers at Carnegie Mellon University, the Colorado School of Mines and the University of California, Davis have come up with a design for a better liposome. Their findings, while theoretical, could provide the basis for efficiently constructing new vehicles for nanodrug delivery.

Liposomes are small containers with shells made of lipids, the same material that makes up the cell membrane. In recent years, liposomes have been used for targeted drug delivery. In this process, the membrane of a drug-containing liposome is engineered to contain proteins that will recognize and interact with complementary proteins on the membrane of a diseased or dysfunctional cell. After the drug-containing liposomes are administered, they travel through the body, ideally connecting with targeted cells where they release the drug.

liposome_853x480-min.jpg

This packaging technique is often used with highly toxic nanodrugs, like chemotherapy drugs, in an attempt to prevent the free drug from damaging non-cancerous cells. However, studies of this model of delivery have shown that in many cases less than 10 percent of the drugs transported by liposomes end up in tumor cells. Often, the liposome breaks open before it reaches a tumor cell and the drug is absorbed into the body’s organs, including the liver and spleen, resulting in toxic side effects.

“Even with current forms of targeted drug delivery, treatments like chemotherapy are still very brutal. We wanted to see how we could make targeted drug delivery better,” said Markus Deserno, professor of physics at Carnegie Mellon and a member of the university’s Center for Membrane Biology and Biophysics.

Deserno and colleagues propose that targeted drug delivery can be improved by making more stable liposomes. Using three different types of computer modeling, they have shown that liposomes can be made sturdier by incorporating a nanoparticle core made of a material like gold or iron and connecting that core to the liposome’s membrane using polymer tethers. The core and tethers act as a hub-and-spoke-like scaffold and shock-absorber system that help the liposome to weather the stresses and strains it encounters as it travels through the body to its target.

Francesca Stanzione and Amadeu K. Sum of the Colorado School of Mines conducted a fine-grained simulation that looked at how the polymer tethers anchor the liposome’s membrane at an atomistic level. Roland Faller of UC Davis did a meso-scale simulation that looked how a number of tethers held on to a small patch of membrane. Each of these simulations allowed researchers to look at smaller components of the liposome, nanoparticle core and tethers, but not the entire structure.

To see the entire structure, Carnegie Mellon’s Deserno and Mingyang Hu developed a coarse-grained model that represents groupings of components rather than individual atoms. For example, one lipid in the cell membrane might have 100 atoms. In a fine-grain simulation, each atom would be represented. In Deserno’s coarse grain simulation, those atoms might be represented by only three pieces instead of 100.

“Its unfeasible to look at the complete construct at an atomistic level. There are too many atoms to consider, and the timescale is too long. Even with the most advanced supercomputer, we wouldn’t have the power to run an atom-level simulation,” Deserno said. “But the physics that matters isn’t locally specific. It’s more like soft matter physics, which can be described at a much coarser resolution.”

Deserno’s simulation allowed the researchers to see how the entire reinforced liposome construct responded to stress and strain. They proposed that if a liposome was given the right-sized hub and tethers, its membrane would be much more resilient, bending to absorb impact and pressure.

Additionally, they were able to simulate how to best assemble the liposome, hub and tether system. They found that if the hub and tether are attached and placed in a solution of lipids, and solvent conditions are suitably chosen, a correctly sized liposome would self-assemble around the hub and tethers.

The researchers hope that chemists and drug developers will one day be able to use their simulations to determine what size core and polymer tethers they would need to effectively secure a liposome designed to deliver a specific drug or other nanoparticle. Using such simulations could narrow down the design parameters, speed up the development process and reduce costs.

 

Lipotype GmbH and NIHS Collaborate

http://www.technologynetworks.com/Metabolomics/news.aspx?ID=184363

NIHS to use the Lipotype Shotgun Lipidomics Technology for lipid analysis.

Lipotype GmbH and the Nestlé Institute of Health Sciences (NIHS) have collaborated to employ the innovative Lipotype Shotgun Lipidomics Technology to analyze lipids in blood for nutritional research. Recently, Lipotype and NIHS have jointly published results of the robustness of the Lipotype Technology. Lipotype envisions a future use of its technology in clinical diagnostics screens for establishing reliable lipid diagnostic biomarkers.

Innovative Lipotype Technology for lipid analysis
The purpose of this collaboration is to enable NIHS to use the Lipotype Shotgun Lipidomics Technology for lipid analysis. The mass spectrometry-based Lipotype technology covers a broad spectrum of lipid molecules and delivers quantitative results in high-throughput. The Nestlé Institute of Health Sciences uses this technology platform for nutritional research. NIHS is a specialized biomedical research institute and is part of Nestlé’s global Research & Development network.

Joint research project reveals robustness of Lipotype Technology
During the collaboration, Lipotype and NIHS conducted a joint research project and demonstrated that the Lipotype technology was robust enough to deliver data with high precision and negligible technical variation between different sites. In addition, important features are the high coverage and throughput, which were confirmed when applying the Lipotype technology.

Lipotype envisions these as important features, required for future use in clinical diagnostics screens, in order to establish and validate reliable lipid diagnostic biomarkers. The results have been published in October 2015, in the European Journal of Lipid Science and Technology (Surma et al. “An Automated Shotgun Lipidomics Platform for High Throughput, Comprehensive, and Quantitative Analysis of Blood Plasma Intact Lipids.”).

Lipids play an important role for health and disease
Lipotype is a spin-off company of the Max-Planck-Institute of Molecular Cell Biology and Genetics in Dresden, Germany. Prof. Kai Simons, CEO of Lipotype explains: “We developed a novel Shotgun-Lipidomics technology to analyze lipids in blood and other biological samples. Our analysis is quick and covers hundreds of lipid molecules at the same time. Our technology can be used to identify disease related lipid signatures.”

 

New Treatment for Obesity Developed

http://www.technologynetworks.com/Metabolomics/news.aspx?ID=183998

Researchers at the University of Liverpool, working with a global healthcare company, have helped develop a new treatment for obesity.
The treatment, which is a once-daily injectable derivative of a metabolic hormone called GLP-1 conventionally used in the treatment of type 2 diabetes, has proved successful in helping non-diabetic obese patients lose weight.

Professor John Wilding, who leads Obesity and Endocrinology research in the Institute of Ageing and Chronic Disease, investigates the pathophysiology and treatment of both obesity and type 2 diabetes and is applying his expertise in this area to work with, and often act as a consultant for, a number of large pharmaceutical companies looking to develop new treatments for obesity and diabetes.

Exciting development

Professor Wilding, said: “The biology of GLP-1 has been a focus of my research for 20 years; in particular when I was working at Hammersmith Hospital in London, I was part of the team that demonstrated that it was involved in appetite regulation; work on GLP-1 has continued during my time in Liverpool. Being involved in the development of a treatment, from the basic research right through to clinical trials in patients is very exciting”.

“It is likely that the treatment will be used initially in very specific situations, such as helping patients who are severely obese. It differs from current treatments used for diabetes, as it has stronger appetite regulating effects but no greater effect on glucose control.”

In 2014 more than 1.9 billion adults worldwide were classed as obese by the World Health Organisation; in the UK numbers have more than tripled since 1980. This Obesity can lead to other serious health-related illnesses including type 2 diabetes, hypertension and obstructive sleep apnoea as well as increasing the risk for many common cancers.

The drug has been approved in the European Union, but has not yet launched in the UK.

Professor Wilding added: “Consultancy like this can help relationship and reputation building and informs my research keeping it at the forefront of developments. It also brings many other benefits such as publications and income generation, which can help support other research, for example by such as funding for pilot projects that can lead to grant applications and investigator-initiated trials funded by the company”.

 

Evidence of How Incurable Cancer Develops

http://www.technologynetworks.com/Metabolomics/news.aspx?ID=184346

Researchers in the West Midlands have made a breakthrough in explaining how an incurable type of blood cancer develops from an often symptomless prior blood disorder.

The findings could lead to more effective treatments and ways to identify those most at risk of developing the cancer.

All patients diagnosed with myeloma, a cancer of the blood-producing bone marrow, first develop a relatively benign condition called ‘monoclonal gammopathy of undetermined significance’ or ‘MGUS’.

MGUS is fairly common in the older population and only progresses to cancer in approximately one in 100 cases. However, currently there is no way of accurately predicting which patients with MGUS are likely to go on to get myeloma.

Myeloma is diagnosed in around 4,000 people each year in the UK. It specifically affects antibody-producing white blood cells found in the bone marrow, called plasma cells. The researcher team from the University of Birmingham, New Cross and Heartlands Hospitals compared the cellular chemistry of bone marrow and blood samples taken from patients with myeloma, patients with MGUS and healthy volunteers.

Surprisingly, the researchers found that the metabolic activity of the bone marrow of patients with MGUS was significantly different to plasma from healthy volunteers, but there were very few differences at all between the MGUS and myeloma samples. The research was funded by the blood cancer charity Bloodwise, which changed its name from Leukaemia & Lymphoma in September.

The findings suggest that the biggest metabolic changes occur with the development of the symptomless condition MGUS and not with the later progression to myeloma.

Dr Daniel Tennant, who led the research at the University of Birmingham, said, “Our findings show that very few changes are required for a MGUS patient to progress to myeloma as we now know virtually all patients with myeloma evolve from MGUS. A drug that interferes with these specific initial metabolic changes could make a very effective treatment for myeloma, so this is a very exciting discovery.”

The research team found over 200 products of metabolism differed between the healthy volunteers and patients with MGUS or myeloma, compared to just 26 differences between MGUS patients and myeloma patients. The researchers believe that these small changes could drive the key shifts in the bone marrow required to support myeloma growth.

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 Rituximab for a Variety of B-cell Malignancies

Curator: Larry H Bernstein, MD, FCAP

 

 

Impact of Rituximab (Rituxan) on the Treatment of B-Cell Non-Hodgkin’s Lymphoma

Non-Hodgkin’s lymphoma (NHL) is the most common hematological malignancy in adults, with B-cell lymphomas accounting for 85% of all NHLs. The most substantial advancement in the treatment of B-cell malignancies, since the advent of combination chemotherapy, has been the addition of the monoclonal anti-CD20 antibody rituximab (Rituxan). Since its initially reported single-agent activity in indolent lymphomas in 1997, the role of rituximab has expanded to cover both indolent and aggressive lymphomas.

This article focuses on the impact of rituximab on the treatment, survival, and long-term outcomes of patients with indolent and aggressive lymphomas over the past two decades.

Keywords: rituximab, non-Hodgkin’s lymphoma
Non-Hodgkin’s lymphoma (NHL) is the most common adult hematological cancer. In 2009, almost 66,000 cases were anticipated in the U.S. alone.1The incidence of NHL in the U.S. over the previous 15 years has increased by approximately 4% annually, despite the decline in age-adjusted incidence rates for all cancers combined.

NHL encompasses a heterogeneous group of lymphomas that have been classified in various ways. In 1995, the World Health Organization developed a classification that included a combination of morphology, immunotyping, genetic features, and clinical syndromes. The goal was to define disease entities of B cells, T cells, and natural killer (NK) cells that pathologists could recognize and that had clinical relevance. The lymphomas were further subdivided into categories based on their clinical behavior (indolent, aggressive, or highly aggressive).2 More recent updates of this classification have clarified some less common entities but have left the overall schema intact.3

B-cell lymphomas account for about 85% of all NHL diagnoses.4 Although many subtypes of NHL exist clinically, most are grouped as either indolent (characterized by a prolonged median survival but generally considered incurable) or aggressive (characterized by rapid growth but with the potential for cure). Because patients with indolent lymphoma eventually die with this disease if they do not die of intercurrent illness, new treatments are needed to prolong survival, with the ultimate goal to provide cure. For patients with aggressive lymphoma, unmet needs include higher initial cure rates, improved salvage chemotherapy options, and less toxic therapies for old and frail patients.

Conventional methods of treatment, including chemotherapy and radiation, are associated with toxicity and lack specific antitumor-targeted activity. Cell–surface proteins, such as CD19, CD20, and CD22, are highly expressed on B-cell lymphomas and represent key potential targets for treatment.

Antibody therapy directed against CD20 has had the most important clinical impact to date. CD20 is thought to be involved in the regulation of intracellular calcium, cell cycle, and apoptosis. CD20 is not shed, modulated, or internalized significantly upon antibody binding, thus making it an ideal target for passive immunotherapy.5

Over the past two decades, significant progress has been made in the development of new therapies for B-cell lymphoma. Perhaps the most important advance is the addition of rituximab (Rituxan, Genentech/Biogen Idec), which the FDA approved for use in the U.S. in 1997. Rituximab is a chimeric (mouse and human) monoclonal antibody directed against the B-cell antigen CD20. It depletes B cells by several mechanisms, including direct antibody-dependent cellular cytotoxicity (ADCC), complement-mediated cell death, and signaling apoptosis.611

Phase 1 trials of two doses of rituximab (500 mg/m2 and 375 mg/m2 for four weeks) showed clinical responses with no dose-limiting toxicity.12 The weekly 375-mg/m2 dose, given for four weeks, was selected for further phase 2 evaluation and is currently the standard single-agent dose and schedule. Since this first reported activity, the role of rituximab has expanded to include both indolent and aggressive lymphomas.

This article addresses the effect of rituximab on survival and long-term outcomes in patients with NHL.

Indolent, Low-Grade Lymphomas

Unlike aggressive lymphomas, indolent B-cell lymphomas are not considered curable with conventional therapies. Many patients are observed for prolonged periods without requiring treatment.13 In one study, more than 50% of the patients remained untreated for a median period of almost six years after diagnosis.14 Treatment goals focus on maintaining good quality of life with minimal symptoms. The indications for treatment include the presence of B symptoms (fevers, night sweats, and weight loss), compromise of normal organ function, bulky disease, or the presence of cytopenias resulting from marrow involvement. Transformation to an aggressive histological pattern warrants treatment for the aggressive component.

Although many active therapies are available for indolent NHL, patients ultimately die of this disease, which is incurable. Additional therapeutic options with improved efficacy and reduced toxicity are still needed for patients with indolent NHL. In light of this unmet need, the FDA’s approval of rituximab for the treatment of relapsed or refractory CD20-positive (CD20+) NHL in 1997 was an important clinical advance. The approval was based on the pivotal trial reported by McLaughlin et al., in which single-agent rituximab brought about significant response rates in heavily pretreated patients with indolent lymphoma.15

Initial Therapy for Indolent (Follicular) Lymphoma

Rituximab as first-line therapy has been widely studied in patients with indolent lymphomas, both as a single agent and in combination with conventional chemotherapy (Table 1). Witzig et al. evaluated the use of single-agent rituximab, 375 mg/m2 weekly for four doses, as an initial therapy for patients with stage III or IV grade 1 follicular lymphoma (FL). In this small phase 2 trial of only 37 patients, the reported objective response rate (ORR) was 72% and the complete remission rate (CRR) was 36%.16 Similarly, a phase 2 study by Hainsworth et al., which evaluated initial therapy in patients with indolent lymphomas, showed response rates in the range of 50%.17

Table 1

Randomized Trials Using Rituximab in First-Line and Relapsed Settings in Indolent Lymphomas

Using rituximab as a first-line therapy in patients with low-tumor-burden, indolent NHL, Colombat et al. reported an ORR of 73%.18 Long-term follow-up results of the completed randomized phase 3 Rituximab ExtendedSchedule Or Re-treatment Trial (RESORT, ECOG 4402 [Eastern Cooperative Oncology Group]) are still pending. In this randomized study, patients received four weekly rituximab treatments. Retreatment is then given as a single dose of rituximab every three months or upon disease progression with four weekly doses. The aim of the study is to define the benefit of maintenance therapy or re-treatment with rituximab (in terms of time to requiring a therapy other than rituximab) when progressive disease is documented.

The benefit of adding rituximab to combination chemotherapy during the initial treatment of FL has been documented in multiple clinical trials over the past decade. The phase 3 trial by Marcus et al. compared cyclophosphamide, vincristine, and prednisone (CVP), with and without rituximab, in 318 previously untreated patients with stage III and IV CD20+ FL.19 The addition of rituximab to CVP (R-CVP) significantly improved time to disease progression (34 months with R-CVP vs. 15 months with CVP, respectively; P < 0.0001) and duration of response (38 months vs. 14 months, respectively; P < 0.0001). Disease-free survival was 21 months with CVP but has not yet been determined in the group receiving R-CVP.

The East German Study Group evaluated the combination of rituximab with mitoxantrone, chlorambucil, and prednisone (MCP), followed by maintenance interferon in treatment-naive patients with stage III/IV CD20+ FL.20 The ORR was 92% with rituximab and 75% with chemotherapy alone (P = 0.0009).

Rituximab was also tested in combination with cyclophosphamide, hydroxydaunorubicin (doxorubicin), Oncovin (vincristine), and prednisone (R-CHOP) as first-line therapy in 428 patients with FL in a randomized phase 3 study with three years of follow-up.21 This combination showed a significant prolongation of time to treatment failure (P < 0.001) and prolonged duration of remission (P = 0.001) with the addition of rituximab. A higher ORR was observed in the group receiving R-CHOP (96%), compared with CHOP alone (90%) (P = 0.011). Even with a short follow-up, overall survival rates improved in the group receiving chemotherapy and rituximab (P = 0.016).

Similar results were seen in the GELA–GOELAMS FL 2000 trial (Groupe d’Etude des Lymphomes de l’Adulte/Groupe Ouest Est des Leucémies etAutres Maladies du Sang). This study was designed to examine the combination of rituximab with cyclophosphamide, hydroxydaunorubicin (doxorubicin), etoposide (VP-16), and prednisolone (CHVP) plus interferon-2 .22 A significant improvement in event-free survival at five years was noted for the rituximab patients (37% vs. 53%, respectively; P = 0.0004).

A meta-analysis of seven randomized controlled trials assessed the value of adding rituximab to conventional chemotherapy for 1,943 patients with FL, mantle-cell lymphoma, and other indolent lymphomas.23 This analysis demonstrated improved overall survival with the combination, as follows:

  • hazard ratio (HR) for mortality, 0.65
  • 95% confidence interval (CI), 0.51–0.79
  • disease control (HR for the disease event, 0.62; 95% CI, 0.55–0.71)
  • response rates (relative risk for response 1.21; 91% CI, 1.16–1.27)

Specifically in FL, overall survival was better with rituximab plus chemotherapy (HR for mortality, 0.60; 95% CI, 0.37–0.98).23 The study authors concluded that the combination of rituximab and chemotherapy for patients with indolent lymphomas was superior to chemotherapy alone with respect to overall survival, disease-free survival, and response rates.23

Relapsed/Refractory Indolent Non-Hodgkin’s Lymphoma

The pivotal trial upon which the initial approval of rituximab was based showed the drug’s efficacy as a single agent in relapsed/refractory indolent NHL.15 Re-treatment with rituximab alone in 57 patients with low-grade FL who had previously responded to single-agent rituximab yielded a response rate of 40% and a similar duration of response, indicating sensitivity to re-treatment with the same agent.24

Davis et al. studied the use of single-agent rituximab in patients with bulky lesions (larger than 10 cm) and relapsed NHL.25 Patients receiving rituximab 375 mg/m2 weekly for four doses had an ORR of 43%. Among patients with a partial response, lesion size decreased by 76%.

The addition of rituximab to standard chemotherapy was found to be beneficial in the treatment of FL patients with relapsed/refractory NHL (see Table 1). An international trial by van Oers et al. evaluated the combination of six cycles of CHOP with rituximab 375 mg/m2 given intravenously on day 1 of each cycle, compared with chemotherapy alone in 465 patients with advanced disease.26 The ORR was higher with the addition of rituximab (85% with R-CHOP vs. 72% with CHOP alone; P < 0.001), and the median progression-free survival rate was also significantly improved in the rituximab group (33.1 vs. 20 months; P < 0.001). The addition of rituximab to the combination of fludarabine, cyclophosphamide, and mitoxantrone (FCM) in a similar group of patients also showed superior responses.27

Rituximab with bendamustine (Treanda, Cephalon) was studied in a phase 2 trial in patients with relapsed disease. This combination was found to be very effective, with an ORR of 92%.28

Maintenance Therapy for Follicular Lymphoma

Some authors consider rituximab to be an ideal medication to use as maintenance therapy for an incurable disease such as FL because of its minimal toxicity and long half-life, which obviates the need for frequent administration.29 The use of rituximab as maintenance therapy after induction treatment has been the subject of several studies (Table 2) and is being evaluated by two large phase 3 trials: Primary Rituximab and Maintenance (PRIMA) and RESORT.30,31

Table 2

Trials Showing Benefit for Maintenance Rituximab after Induction Therapy for Indolent Lymphomas

In the PRIMA trial, patients with previously untreated FL requiring therapy received a rituximab–chemotherapy regimen designated by the participating center as R-CHOP, R-CVP, or R-FCM. Responding patients were then randomly assigned to receive observation or scheduled re-treatment with rituximab as a single dose every eight weeks for two years. The RESORT trial was designed for asymptomatic patients with low-tumor-burden, indolent NHL (as discussed in detail on page 149).

The Swiss Group for Clinical Cancer Research (SAKK) evaluated maintenance rituximab following induction with rituximab monotherapy in a phase 3 trial in patients with newly diagnosed NHL and in previously treated patients with FL.32 In this study, the maintenance schedule consisted of four infusions at two-month intervals. Event-free survival was significantly longer among patients who received this maintenance schedule.

A phase 2 trial by the Minnie Pearl Cancer Research Network compared maintenance rituximab (four weekly doses repeated every six months for two years) with re-treatment using rituximab upon disease progression.33The study showed significant prolongation of progression-free survival in the maintenance therapy group (31.3 vs. 7.4 months, respectively; P = 0.007), although no difference in overall survival or duration benefit from rituximab was observed between the two cohorts.

ECOG 1496 was a study that compared the use of maintenance rituximab with observation after induction with a non-rituximab chemotherapy regimen (CVP) in 282 patients with newly diagnosed FL.34 Improvement in progression-free survival at three years (68% with rituximab vs. 33% with CVP; P < 0.001) and overall survival at three years (91% vs. 86%, respectively; P = 0.08) were noted in the maintenance arm. In the relapsed setting, the prolonged use of rituximab was found to be beneficial with improved progression-free survival when it was used after CHOP or R-CHOP and after treatment with R-FCM.26,35

Although significant evidence exists for the improved progression-free survival with the use of maintenance therapy for FL, the benefit in terms of overall survival is still controversial. Moreover, because different dosing schedules were used in these studies, no data are available for the optimal dosing schedule of maintenance therapy and the recommended duration of this treatment.

Rituximab plus Chemotherapy: Effect on Survival In Follicular Lymphoma

There is no doubt that the clinical development of rituximab has been a significant breakthrough in the field of indolent lymphomas. However, its effect on overall survival in this group of patients is still open to debate.

An analysis of survival in patients 15 years of age and older with NHL diagnosed between 1990 and 2004, using data from the Surveillance, Epidemiology and End Results (SEER) program, revealed a markedly improved outcome for patients with NHL in recent years. This finding may be related, in part, to the addition of rituximab.36

A large retrospective analysis by Swenson et al. was conducted to examine survival rates of 14,564 patients with FL diagnosed between 1978 and 1999 in the U.S.37 Improvement in survival was noted over the past 25 years, and a reduction in the relative risk of death by 1.8% per year was observed from 1983 to1999.

In a second analysis, the Southwest Oncology Group (SWOG) looked at the survival of patients with FL on three large randomized clinical trials between 1974 and 2000.38 Overall survival rates improved over this period of time. The greatest improvement was observed with the most recent treatment approach consisting of CHOP with an anti-CD20 monoclonal antibody.

The study by Marcus et al., published in 2008, showed improved survival rates among untreated patients receiving CVP plus rituximab when compared with CVP alone (four-year survival, 83% vs. 77%, respectively; P= 0.029).19 Other studies, including a Cochrane meta-analysis, have shown similar trends toward improved survival.23,26,34

These observations can be attributed to multiple factors, including improved supportive care measures, enhancements in education of physicians and patients, and better treatments of relapsed and transformed cases.39 Despite these uncertainties regarding its effect on overall survival, it is clear that rituximab has substantially advanced the treatment of indolent lymphomas in the last decade.

Diffuse Large B-Cell Lymphoma

As the most common high-grade form of NHL, diffuse large B-cell lymphoma (DLBCL) accounts for more than 30% of new diagnoses. The median age of presentation is 60 years. Unlike indolent lymphomas, DLBCL is an aggressive lymphoma; if it is untreated, survival can be measured in months. More than 70% of patients with DLBCL present at an advanced stage, and systemic chemotherapy is the foundation of treatment. Since its development in the 1970s, CHOP has been the mainstay of treatment for this group of patients.

A milestone phase 3 trial found that complex regimens that included the addition of other chemotherapy agents to CHOP did not demonstrate any significant difference in overall survival, disease-free survival, or remission rates over CHOP.4043 Moreover, CHOP was associated with significantly less toxicity and cost.

Based on these results, CHOP remained the gold standard of therapy for DLBCL. Nonetheless, long-term remission occurred in only about 45% of patients, so that more than half of patients relapsed with the best therapy possible in the early 1990s. A relatively small percentage of relapsed DLBCL patients (25%–50%) might have been “salvaged” with high-dose chemotherapy and stem-cell support, yet many patients were not even eligible for such therapy.

Thus, in the early 1990s, the addition of more chemotherapy drugs into complex regimens had not improved results with CHOP, and there was a sense that future improvements in therapy would not come from additional “standard” drugs. While rituximab was approved for treatment of low-grade lymphoma in 1997, several trials combining rituximab with CHOP (R-CHOP) for aggressive lymphomas began prior to that time. Because rituximab-related toxicities were not overlapping with those of CHOP, both CHOP and rituximab could be administered at full doses. Results from large international, randomized trials have demonstrated the significant benefits of the addition of rituximab to standard chemotherapy for DLBCL. These trials are summarized next.

Previously Untreated Diffuse Large B-Cell Lymphoma

Based on the efficacy of rituximab in low-grade lymphomas, Vose et al. conducted a phase 2 study of rituximab with CHOP chemotherapy in 33 previously untreated patients with advanced-stage, aggressive B-cell lymphoma.44 Rituximab at a dose of 375 mg/m2 was administered on day 1 of each of six cycles of CHOP. The ORR was 94%; 61% of patients had complete responses (CRs), and 33% had partial responses (PRs). This was the first report that demonstrated an improved efficacy of the combination without worsening toxicity.

GELA investigators randomized previously untreated elderly patients (60–80 years of age) to eight cycles of CHOP alone (197 patients) or eight cycles of R-CHOP given on day 1 of each cycle (202 patients).45 The rate of CRs was significantly higher in the rituximab group (76% vs. 63% receiving CHOP alone, P = 0.005). Sixty percent of patients exhibited features of poor risk, with age-adjusted International Prognostic Index (aaIPI) scores of 2 to 3. With a median follow-up of two years, event-free survival rates (57% vs. 38%; P < 0.001) and overall survival rates (70% vs. 57%; P = 0.007) were significantly higher with rituximab (Table 3). Furthermore, toxicity was not greater with the addition of rituximab.

Table 3

Trials Using Rituximab for Diffuse Large B-Cell Lymphomas in the First-Line Setting

A long-term analysis at seven years has confirmed the benefit of the addition of rituximab.46 Event-free survival (42% with R-CHOP vs. 25%; P < 0.0001), progression-free survival (52% vs. 29%, respectively; P < 0.0001) and disease-free survival (66% vs. 42% respectively, P = 0.0001) were all statistically better for patients treated with combination therapy.

A retrospective analysis of the GELA trial suggested that R-CHOP increased overall survival preferentially in bcl-2–positive patients compared with CHOP alone.47 These data suggested that rituximab may overcome chemotherapy resistance associated with bcl-2 in patients with DLBCL. However, other retrospective analyses have led to conflicting results on whether the benefit of R-CHOP is primarily or only observed in bcl-2expressing DLBCL.

Habermann et al. randomly assigned patients older than 60 years of age to receive CHOP or R-CHOP, with a second random assignment to maintenance rituximab therapy or observation in responders (see Table 3).48This study demonstrated the benefit of the addition of rituximab to CHOP using a modified schedule of rituximab administration. Three-year failure-free survival rates were 53% and 46% (P = 0.04). Failure-free survival was higher for patients who received maintenance therapy with rituximab after CHOP but not for patients who received R-CHOP initially.

The trials described above established R-CHOP as standard first-line therapy for elderly patients with DLBCL. With respect to younger patients, the MabThera (rituximab) International Trial (MInT) confirmed the benefit of adding rituximab to standard chemotherapy in 824 patients (18 to 60 years of age) with only zero (0) to one risk factor, as assessed by the IPI (seeTable 3).49 Patients with stage II to IV or stage I disease with bulky lymphadenopathy were randomly assigned to six cycles of CHOP-like chemotherapy with or without the addition of rituximab. Radiation therapy was subsequently administered to initial sites of bulky disease. Three-year event-free survival rates (79% vs. 59%; P < 0.0001) and overall survival rates (93% vs. 84%; P = 0.00001) were both significantly higher for patients treated with the addition of rituximab. There were no additional major adverse effects.

Sehn et al. compared outcomes during a three-year period; 18 months pre- and post-inclusion of rituximab in standard treatment protocols guided care for patients with newly diagnosed advanced-stage DLBCL in British Columbia.50 All age and risk factor groups were included. Adding rituximab resulted in dramatic improvement in both progression-free survival and overall survival (Figure 1). These studies have indicated significant benefit for the addition of rituximab to chemotherapy for the treatment of DLBCL in a wide range of patient ages and risk categories. Although adding other cytotoxic chemotherapy agents to CHOP failed to improve outcomes, R-CHOP is now the gold standard for treating DLBCL in all subgroups.43

Figure 1

Overall survival according to treatment regimen in diffuse large B-cell lymphoma. Results of a randomized trial of non-rituximab containing regimens as historical controls for British Columbia outcome data with R-CHOP. MACOP-B = methotrexate, Adriamycin,

Relapsed/Refractory Diffuse Large B-Cell Lymphoma

Coiffier et al. conducted a randomized phase 2 trial to evaluate the efficacy and tolerability of rituximab in patients with relapsed/refractory DLBCL, mantle-cell lymphoma, or other intermediate-grade or high-grade B-cell lymphomas and previously untreated patients older than 60 years of age.51 Fifty-four patients received eight weekly infusions of rituximab 375 mg/m2 in arm A or one infusion of 375 mg/m2, followed by seven weekly infusions of 500 mg/m2in arm B. A total of five complete responses and 12 partial responses were observed among the 54 enrolled patients, with no difference between the two doses. The ORR was 31%. An analysis of prognostic factors showed that response rates were lower in patients with refractory disease, in patients with lymphoma not classified as DLBCL, and patients with a tumor larger than 5 cm in diameter. Single-agent rituximab is active in aggressive NHL but not as active as in indolent NHL. This finding led to the use of combinations of rituximab plus chemotherapy in such patients.

The combination of rituximab, ifosfamide, carboplatin, and etoposide (R-ICE) was evaluated in relapsed DLBCL for cytoreduction prior to autologous hematopoietic stem cell transplantation (HSCT).52 Thirty-six eligible patients received rituximab plus ICE (RICE), and 34 patients received all three planned cycles. The CR rate was 53%, significantly better than the 27% CR rate (P = 0.01) achieved among 147 similar consecutive historical control patients with DLBCL treated with ICE; the PR rate was 25%. Progression-free survival in patients who underwent transplantation after RICE was marginally better than for 95 consecutive historical controls who underwent transplantation after ICE alone, but the results did not reach statistical significance (54% with RICE vs. 43% with ICE alone at two years, respectively; P = 0.25). Preliminary results of the CORAL study (Collaborative Trial in Relapsed Aggressive Lymphoma) demonstrated a decreased response to rituximab in the salvage setting of patients previously treated with rituximab-containing regimens.53

In a phase 2 study, rituximab was evaluated in addition to etoposide, prednisone, Oncovin (vincristine), doxorubicin, and cyclophosphamide (EPOCH) in patients with relapsed or refractory aggressive NHL.54 The ORR of 68% included 28% of patients in complete remission. At three years, event-free survival and overall survival rates were 28% and 38%, respectively.

Few studies have explored the use of rituximab as an adjunct to autologous HSCT after high-dose chemotherapy in patients with relapsed DLBCL.5557 These studies have reported positive results with rituximab in this setting. Larger, randomized trials are needed to establish a definitive role for rituximab in these patients. While overall the data on rituximab efficacy in aggressive NHL is not as strong in relapsed patients as for initial R-CHOP, rituximab is active and additional confirmatory studies are needed in various relapsed settings.

Maintenance Therapy for Diffuse Large B-Cell Lymphoma

Unlike the situation with indolent lymphomas, there is no apparent benefit to maintenance rituximab in DLBCL. In an ECOG trial, responding patients were randomly assigned to receive maintenance rituximab or to observation alone.48 Two-year failure-free survival was 76% for maintenance therapy and 61% for observation alone, but these figures were confounded depending on whether rituximab was used initially. No significant differences in survival were seen when rituximab was included either as maintenance or as induction therapy. Failure-free survival was prolonged with maintenance therapy after CHOP but not after R-CHOP. This study confirmed the role of R-CHOP as standard first-line therapy in older DLBCL patients, with maintenance therapy to be used only for patients not previously treated with rituximab.

ADVERSE EFFECTS

Rituximab is usually well tolerated, and toxicities are generally mild.12,24,58Common side effects include pruritus, nausea, vomiting, dizziness, headaches, fevers, and rigors. A major concern is the potential for an infusion-related reaction, such as rigors, chills, anaphylactic reactions potentially leading to myocardial infarction and cardiogenic shock. These reactions occur most commonly during the first administration of rituximab. Although infusion reactions are rarely fatal, predisposing cardiac conditions can increase the risk of death. Pre medication with acetaminophen and antihistamines is recommended prior to infusion. Reactions usually abate if the infusion is discontinued and can then be restarted at a slower rate. The benefit of premedication with glucocorticoids is not entirely clear, but they are useful if a reaction occurs. Mucocutaneous reactions, including Stevens–Johnson syndrome, have also been reported within one to 13 weeks following rituximab exposure.

Tumor lysis syndrome has also occurred in patients with bulky lymphoma. Hepatitis B reactivation with fulminant hepatitis, hepatic failure, and death have been reported in patients with previous hepatitis B infection who have been treated with rituximab. Consultation with a hepatologist and administration of antiviral therapy should be considered if hepatitis B antigen is detectable. The risk of reactivation of hepatitis C is not well defined. The use of live vaccines, including those against herpes zoster, is not recommended during rituximab therapy secondary to the risk of causing an active infection. Rituximab-treated patients are also at risk for other viral infections, including cytomegalovirus, herpes simplex, parvovirus B19, and West Nile virus.

Late-onset neutropenia has been described as a possible complication of adding rituximab to chemotherapy.59 In a retrospective review, patients who received chemotherapy plus rituximab for CD20+, B-cell NHL had a higher rate of late-onset neutropenia compared with historical controls receiving chemotherapy alone.

A study published in 2009 reported 57 cases of progressive multifocal leukoencephalopathy (PML) following the administration of rituximab, usually with additional therapy, in HIV-negative patients.60 PML, a viral infection that affects the white matter of the brain, is usually fatal. This cohort of patients was treated with a median of six doses of rituximab. The median time from last rituximab dose to PML diagnosis was 5.5 months, and median survival after the diagnosis of PML was two months. In accordance with these data, the FDA issued a boxed (black-box) warning.

Reversible posterior leukoencephalopathy (RPLE), a subacute neurological syndrome manifested as headaches, cortical blindness, and seizures with a characteristic appearance on magnetic resonance imaging (MRI), has also been described in rare cases.61,62 It is not clear whether these events are directly related to rituximab, because most of these patients have received multiple therapies, but RPLE has also been reported after other antibody and small-molecule therapeutics. Cardiac arrhythmias, renal toxicity, and bowel obstruction with perforation have also been reported.57

Rituximab induces B-cell depletion, which may compromise the immune system; however, recovery of the normal B-cell population usually occurs six to nine months after discontinuation of therapy.15 Despite this depletion, rituximab has not been definitively shown to cause a significant decrease in circulating immunoglobulin levels, although this may occur with more prolonged maintenance strategies. Stable immunoglobulin levels are likely to reflect that plasma cells are long-lived and do not express CD20.

In a prospective study, van der Kolk et al. investigated the effect of rituximab on the humoral immune response to two primary antigens and two recall antigens.63 After rituximab treatment, the humoral immune response to the recall antigens was significantly decreased when compared with the response before treatment.

FUTURE DIRECTIONS

Attempts to improve upon rituximab have focused on antibody engineering, including humanized instead of chimeric antibodies, stronger binding affinity for CD20, or enhancing effector functions such as antibody-dependent, cell-mediated cytotoxicity (ADCC) or complement activation. Ofatumumab (Arzerra, GlaxoSmithKline) is a humanized monoclonal anti-CD20 antibody that targets a small loop epitope of CD20. Compared with rituximab, in the laboratory it delivers stronger complement-dependent cytotoxicity, even in lymphoma cells with low expression of CD20. Approved by the FDA in October 2009 for the treatment of fludarabine and alemtuzumab–refractory chronic lymphocytic leukemia (CLL), the drug also showed activity in relapsed/refractory FL.64,65

Additional humanized antibodies under development include some with enhanced ADCC, stronger binding to low-affinity polymorphisms of FcgRIII, or targeting other epitopes on the CD20 molecule. Whether these agents are more effective, less immunogenic, or faster to infuse with fewer infusion reactions resulting may be difficult to determine.

Other proteins on the surface of B cells are also potential antibody targets. CD22 has a pattern of expression similar to that of CD20 on normal and malignant B lymphocytes, and it is targeted by epratuzumab (UCB/Immunomedics).66,67 Because CD22 is internalized upon antibody binding, it might be better suited for delivering toxins inside CD22+ cells. Examples of this approach include inotuzumab ozogamicin (CMC-544, Wyeth), an anti-CD22 immunoconjugate with the antitumor antibiotic calicheamicin, and CAT-3888 (Cambridge Antibody Technology), formerly called BL22, which uses a Pseudomonas exotoxin fragment.68,69

CONCLUSION

Rituximab (Rituxan) has changed the treatment paradigms and outcomes for all CD20+ NHL and represents arguably the most noteworthy advance in lymphoma treatment over the past decade. In patients with NHL, the addition of rituximab to standard treatment significantly enhanced response to therapy and overall outcomes. Rituximab is currently approved for treatment of relapsed and refractory indolent lymphomas as single-agent therapy and as initial therapy in combination with standard chemotherapy regimens. In patients with DLBCL, it is approved for use as initial therapy with CHOP or other anthracycline-based chemotherapy. The drug was also recently approved for use with chemotherapy in previously treated and untreated patients with CLL.

Benefits have been sustained among all age groups, and the drug has been safe and well tolerated in elderly patients as well. Overall survival of patients with NHL has improved over the last two decades. While some of this improvement may stem from earlier or more precise diagnosis and better supportive care, the results of many trials reviewed in this article indicate significant improvement in outcomes with the addition of rituximab to the therapeutic armamentarium.

Despite these advances, questions remain, mainly in the field of indolent lymphomas. More research is under way to establish the optimal schedule, timing, and duration for maintenance rituximab. Reports of clinical trials demonstrating longer follow-up of indolent lymphoma are eagerly awaited in an attempt to clarify the effect of rituximab on overall survival.

Rituximab represents a paradigm shift in treatment of B-cell NHL; it marks the beginning of a new age of targeted therapies in oncology, being the first approved therapeutic monoclonal antibody for cancer. In the years to come, we anticipate more clinical trials combining rituximab with targeted treatments that might further improve outcomes while minimizing toxicity.

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