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Posts Tagged ‘CD47’


Author/Curator: Ritu Saxena, PhD

For several decades, research efforts have focused on targeting progression of cancer cells in primary tumors. Primary tumor cell targeting strategies include standard chemotherapy and immunotherapy and modulation of host microenvironment including tumor vasculature. However, cancer progression is comprised of both primary tumor growth and secondary metastasis (Langley RR and Fidler IJ. Tumor cell-organ microenvironment interactions in the pathogenesis of cancer metastasis. Endocr Rev. 2007 May;28(3):297-321; http://www.ncbi.nlm.nih.gov/pubmed/17409287). Owing to the property of unilimited cell division, cells in primary tumor increase rapidly in number and density and are able to favorably influence their microenvironment. Metastasis, on the other hand, depends on the ability of cancer cells to disseminate, circulate, adapt to the harsh environment and seed in different organs to establish secondary tumors. Although tumor cells are shed into the circulation in large numbers since early stages of tumor formation, few tumor cells can survive and proceed to overt metastasis. (Husemann Y et al. Systemic spread is an early step in breast cancer. Cancer Cell. 2008 Jan;13(1):58-68; http://www.ncbi.nlm.nih.gov/pubmed/18167340). Tight vascular wall barriers, unfavorable conditions for survival in distant organs, and a rate-limiting acquisition of organ colonization functions are just some of the impediments to the formation of distant metastasis (Chiang AC and Massagué J. Molecular basis of metastasis. N Engl J Med. 2008 Dec 25;359(26):2814-23; http://www.ncbi.nlm.nih.gov/pubmed/19109576).

It has been hypothesized that metastasis is initiated by a subpopulation of circulating tumor cells (CTC) found in the blood of patients. Therefore, understanding the function of CTC and targeting the CTC is gaining attention as a possible therapeutic avenue in carcinoma treatment.

CTCs

Figure: Circulating tumor cells in the metastatic cascade

(Image source: Chaffer CL and Weinberg RA. Science 2011,331, pp. 1559-1564; http://www.ncbi.nlm.nih.gov/pubmed/21436443)

Isolation of CTC

Initial methods relied on the difference in physical properties of cells. When spun in a centrifuge, different cells in the blood sample settle in separate layers based on their byoyancy, and CTC are found in the white blood cell fraction. Because CTC are generally larger than white blood cells, a size-based filter could be used to separate the cell types (Vona G, et al, Isolation by size of epithelial tumor cells : a new method for the immunomorphological and molecular characterization of circulating tumor cells. Am J Pathol, 2000 Jan;156(1):57-63; http://www.ncbi.nlm.nih.gov/pubmed/10623654).

Herbert A Fritsche, PhD, Professor and Chief, Clinical Chemistry, Department of Laboratory Medicine, The University of Texas, MD Anderson Cancer Center, demonstrated that the CTC can be captured using antibody labeled magnetic beads, either in positive or negative selection schema. After the circulating tumor cells are isolated, they may be characterized by immunohistochemistry and counted.  Alternatively, these cells may be characterized by gene expression analysis using RT-PCR. One of the CTC detection methods, Veridex Inc, Cell Search Assay, has been cleared by the US FDA for use as a prognostic test in patients with metastatic cancers of the breast, prostate and colon. This technology relies on the expression of epithelial cellular adhesion molecular (EpCAM) by epithelial cells and the isolation of these cells by immunomagnetic capture using anti-EpCAM antibodies.  Enriched CTC are identified by immunofluorescence. Martin Fleisher, PhD, Chair, Department of Clinical Laboratories, Memorial Sloan-Kettering Cancer Center discussed in a webinar at the biomarker symposia, Cambridge Healthtech Institute, that every new technology has shortcomings, and the reliance on cancer cells to express sufficient EpCAM to enable capture may affect the role of this technology in future clinical use. Heterogeneous downregulation of epithelial surface antigen in invasive tumor cells has been reported. Thus, alternative methods to detect CTC are being developed. These new methods include-

  1. Flow cytometry that sorts cells by size and surface antigen expression.
  2. CTC microchips that are designed to capture CTC as whole blood flows past EpCAM-coated mirco-posts.
  3. Enrichment by filtration using filters with a pore size of 7-8 µm, that permits smaller red blood cell, leukocytes, and platelets to pass, but captures CTC that have diameters of about 12-15 µm.

Better identification of CTC

Baccelli et al (2013) developed a xenograft assay and demonstrated that the primary human luminal breast cancer CTC contain metastasis-initiated cells (MICs) that give rise to bone, lung and liver metastases in mice. These MIC-containing CTC populations expressed EPCAM, CD44, CD47 and MET. It was observed that in a small cohort of patients with metastases, the number of CTC expressing markers EPCAM,CD44, CD47 and MET, but not of bulk EPCAM+ CTC, correlated with lower overall survival and increased number of metastasic sites. These data describe functional circulating MICs and associated markers, which may aid the design of better tools to diagnose and treat metastatic breast cancer. The findings were published in the Nature Biotechnology journal recently (Baccelli I, et al. Identification of a population of blood circulating tumor cells from breast cancer patients that initiates metastasis in a xenograft assay. Nature Biotechnology 2013 31, 539–544; http://www.ncbi.nlm.nih.gov/pubmed/23609047).

CTC as prognostic and predictive factor for cancer progression

Martin Fleisher, PhD states “detecting CTC in peripheral blood of patients with cancer has become a clinically relevant and important prognostic biomarker and has been shown to be a predictive biomarker post-therapy. But, key to the use of CTC as a biomarker is the technology designed to enrich cancer cells from peripheral blood.”

Since CTC isolation methods started being established, correlation studies between the cells and a patient’s disease emerged. In 2004, investigators at the Department of Breast Medical Oncology, University of Texas MD Anderson Cancer Center (Houston, TX) discovered that the CTC were associated with disease progression and survival in metastatic breast cancer. The clinical trial recruited 177 patients with measurable metastatic breast cancer for levels of CTC both before the patients were to start a new line of treatment and at the first follow-up visit. The progression of the disease or the response to treatment was determined with the use of standard imaging studies at the participating centers. Patients in a training set with levels of CTC equal to or higher than 5 per 7.5 ml of whole blood, as compared with the group with fewer than 5 CTC per 7.5 ml, had a shorter median progression-free survival (2.7 months vs. 7.0 months, P<0.001) and shorter overall survival (10.1 months vs. >18 months, P<0.001). At the first follow-up visit after the initiation of therapy, this difference between the groups persisted (progression-free survival, 2.1 months vs. 7.0 months; P<0.001; overall survival, 8.2 months vs. >18 months; P<0.001), and the reduced proportion of patients (from 49 percent to 30 percent) in the group with an unfavorable prognosis suggested that there was a benefit from therapy.  Thus, the number of CTC was found to be an independent predictor of progression-free survival and overall survival in patients with metastatic breast cancer (Cristofanilli M, et al, Circulating tumor cells, disease progression, and survival in metastatic breast cancer. N Engl J Med. 2004 Aug 19;351(8):781-91; http://www.ncbi.nlm.nih.gov/pubmed/15317891).

Similar results have been observed in other cancer types, including prostate and colorectal cancer. The Cell Search System developed by Veridex LLC (Huntingdon Valley, PA) enumerated CTC from 7.5 mL of venous blood and was used to compare the outcomes from three prospective multicenter studies investigating the use of CTC to monitor patients undergoing treatment for metastatic breast, colorectal, or prostate cancer. Evaluation of CTC at anytime during the course of disease allowed assessment of patient prognosis and is predictive of overall survival (Miller MC, et al. Significance of Circulating Tumor Cells Detected by the CellSearch System in Patients with Metastatic Breast Colorectal and Prostate Cancer. J Oncol. 2010; http://www.ncbi.nlm.nih.gov/pubmed/20016752). In addition, the CTC test may permit the oncologist to make an early decision to discontinue first line therapy for metastatic breast cancer and pursue more aggressive alternative treatments.

Genetic analysis of CTC

Additional studies have analyzed the genetic mutations that the cells carry, comparing the mutations to those in a primary tumor or correlating the findings to a patient’s disease severity or spread. In one study, lung cancer patients whose CTC carried a mutation known to cause drug resistance had faster disease progression than those whose CTC lacked the mutation. The investigators analyzed the evolutionary aspect of cancer progression and studied the precursor cells of metastases directly for the identification of prognostic and therapeutic markers. Single disseminated cancer cells isolated from lymph nodes and bone marrow of 107 consecutive esophageal cancer patients were analyzed by whole-genome screening which revealed that primary tumors and lymphatically and hematogenously disseminated cancer cells diverged for most genetic aberrations. Chromosome 17q12-21, the region comprising HER2, was identified as the most frequent gain in disseminated tumor cells that were isolated from both ectopic sites. Furthermore, survival analysis demonstrated that HER2 gain in a single disseminated tumor cell but not in primary tumors conferred high risk for early death (Stoecklein NH, et al. Direct genetic analysis of single disseminated cancer cells for prediction of outcome and therapy selection in esophageal cancer. Cancer Cell. 2008 May;13(5):441-53; http://www.ncbi.nlm.nih.gov/pubmed/18455127).

The abovementioned studies indicate that CTC blood tests have been successfully used to track the severity of a cancer or efficacy of a treatment. In conclusion, the evolution of the CTC technology will be critical in the emerging area of targeted therapy.  With the development and use of new technologies, the links between the genomic information and CTC could be explored and established for targeted therapy.

Challenges in CTC research

  1. Potential clinical significance of CTC has been demonstrated as early detection, diagnostic, prognostic, predictive, surrogate, stratification, and pharmacodynamic biomarkers. Hong B and Zu Y (2013) discuss that “the role of CTC as a disease marker may be unique in different clinical conditions and should be carefully interpreted. A good example is the comparison between the prognostic and predictive biomarkers. Both biomarkers employ progression-free survival and overall survival for data interpretation; however, the prognostic biomarker is independent of specific drug treatment or therapy, and used for the determination of outcomes before treatment, while the predictive biomarker is related to a particular treatment to predict the response. Furthermore, inconsistent results are increasingly reported among the various CTC assay methods, specifically pertaining to results for the CTC detection rate, patient positivity rate, and the correlation between the presence of CTC and survival rate (Hong B and Zu Y. Detecting circulating tumor cells: current challenges and new trends. Source. Theranostics. 2013 Apr 23;3(6):377-94; http://www.ncbi.nlm.nih.gov/pubmed/23781285).
  2. Heterogeneity in CTC along with several other technical factors contribute to discordance, including the changes in methodology, lack of reference standard, spectrum and selection bias, operator variability and bias, sample size, blurred clinical impact with known clinical/pathologic data, use of diverse capture antibodies from different sources, lack of awareness of the pre-analytical phase, oversimplification of the cytopathology process, use of dichotomous decision criteria, etc (Sturgeon C. Limitations of assay techniques for tumor markers. In: (ed.) Diamandis EP, Fritsche HA, Lilja H, Chan DW, Schwartz MK. Tumor markers: physiology, pathobiology, technology, and clinical applications. Washington, DC: AACC Press. 2002:65-82; Gion M and Daidone MG. Circulating biomarkers from tumour bulk to tumour machinery: promises and pitfalls. Eur J Cancer. 2004;40(17):2613-2622; http://www.ncbi.nlm.nih.gov/pubmed/15541962). Therefore, employing a standard protocol is essential in order to minimize a lot of inconsistencies and technical errors.
  3. CTC in a small amount of blood sample might not represent the actual CTC count in the whole blood. In fact, it has been reported that the Cell Search system might undercount the number of CTC. Nagrath et al (2007) have demonstrated that the average CTC number per mL of whole blood is approximately 79-155 in various cancers (Nagrath S, et al. Isolation of rare circulating tumous cells in cancer patients by microchip technology. Nature. 2007;450(7173):1235-1239; http://www.ncbi.nlm.nih.gov/pubmed/18097410). In addition, an investigative CellSearch Profile approach (for research use only) detected an approximately 30-fold higher number of the median CTC in the same paired blood samples (Flores LM, et al. Improving the yield of circulating tumour cells facilitates molecular characterisation and recognition of discordant HER2 amplification in breast cancer. Br J Cancer. 2010;102(10):1495-502; http://www.ncbi.nlm.nih.gov/pubmed/20461092). Such measurement discrepancies indicate that the actual CTC numbers in the blood of patients could be at least 30-100 fold higher than that currently reported by the only FDA-cleared CellSearch system.

Thus, although promising, the CTC technology faces several challenges both in detection and interpretation, which has resulted in its limited clinical acceptance and use. In order to prepare the CTC technology for future widespread clinical acceptance, a comprehensive guideline for all phases of CTC technology development was published by the Foundation for the National Institutes of Health (FNIH) Biomarkers Consortium. The guidelines describe methods for interactive comparisons of proprietary new technologies, clinical trial designs, a clinical validation qualification strategy, and an approach for effectively carrying out this work through a public-private partnership that includes test developers, drug developers, clinical trialists, the FDA and the National Cancer Institute (NCI) (Parkinson DR, et al. Considerations in the development of circulating tumor cell technology for clinical use. J Transl Med. 2012;10(1):138; http://www.ncbi.nlm.nih.gov/pubmed/22747748).

Reference:

  1. Langley RR and Fidler IJ. Tumor cell-organ microenvironment interactions in the pathogenesis of cancer metastasis. Endocr Rev. 2007 May;28(3):297-321; http://www.ncbi.nlm.nih.gov/pubmed/17409287
  2. Husemann Y et al. Systemic spread is an early step in breast cancer. Cancer Cell. 2008 Jan;13(1):58-68; http://www.ncbi.nlm.nih.gov/pubmed/18167340
  3. Chiang AC and Massagué J. Molecular basis of metastasis. N Engl J Med. 2008 Dec 25;359(26):2814-23; http://www.ncbi.nlm.nih.gov/pubmed/19109576
  4. Vona G, et al, Isolation by size of epithelial tumor cells : a new method for the immunomorphological and molecular characterization of circulating tumor cells. Am J Pathol, 2000 Jan;156(1):57-63; http://www.ncbi.nlm.nih.gov/pubmed/10623654
  5. Baccelli I, et al. Identification of a population of blood circulating tumor cells from breast cancer patients that initiates metastasis in a xenograft assay. Nature Biotechnology 2013 31, 539–544; http://www.ncbi.nlm.nih.gov/pubmed/23609047
  6. Cristofanilli M, et al, Circulating tumor cells, disease progression, and survival in metastatic breast cancer. N Engl J Med. 2004 Aug 19;351(8):781-91; http://www.ncbi.nlm.nih.gov/pubmed/15317891
  7. Miller MC, et al. Significance of Circulating Tumor Cells Detected by the CellSearch System in Patients with Metastatic Breast Colorectal and Prostate Cancer. J Oncol. 2010; http://www.ncbi.nlm.nih.gov/pubmed/20016752
  8. Stoecklein NH, et al. Direct genetic analysis of single disseminated cancer cells for prediction of outcome and therapy selection in esophageal cancer. Cancer Cell. 2008 May;13(5):441-53; http://www.ncbi.nlm.nih.gov/pubmed/18455127
  9. Hong B and Zu Y. Detecting circulating tumor cells: current challenges and new trends. Source. Theranostics. 2013 Apr 23;3(6):377-94; http://www.ncbi.nlm.nih.gov/pubmed/23781285
  10. 10. Sturgeon C. Limitations of assay techniques for tumor markers. In: (ed.) Diamandis EP, Fritsche HA, Lilja H, Chan DW, Schwartz MK. Tumor markers: physiology, pathobiology, technology, and clinical applications. Washington, DC: AACC Press. 2002:65-82
  11. Gion M and Daidone MG. Circulating biomarkers from tumour bulk to tumour machinery: promises and pitfalls. Eur J Cancer. 2004;40(17):2613-2622; http://www.ncbi.nlm.nih.gov/pubmed/15541962
  12. Nagrath S, et al. Isolation of rare circulating tumous cells in cancer patients by microchip technology. Nature. 2007;450(7173):1235-1239; http://www.ncbi.nlm.nih.gov/pubmed/18097410
  13. Flores LM, et al. Improving the yield of circulating tumour cells facilitates molecular characterisation and recognition of discordant HER2 amplification in breast cancer. Br J Cancer. 2010;102(10):1495-502; http://www.ncbi.nlm.nih.gov/pubmed/20461092
  14. Chaffer CL and Weinberg RA. Science 2011,331, pp. 1559-1564; http://www.ncbi.nlm.nih.gov/pubmed/21436443

Other related articles on circulation cells as biomarkers published on this Open Access Scientific Journal, include the following:

Blood-vessels-generating stem cells discovered

Ritu Saxena, PhD

https://pharmaceuticalintelligence.com/2012/10/22/blood-vessel-generating-stem-cells-discovered/

Cardiovascular and circulating endothelial cells as BIOMARKERS for prediction of Disease progression risks

Statins’ Nonlipid Effects on Vascular Endothelium through eNOS Activation Curator, Author,Writer, Reporter: Larry Bernstein, MD, FCAP

Cardiovascular Outcomes: Function of circulating Endothelial Progenitor Cells (cEPCs): Exploring Pharmaco-therapy targeted at Endogenous Augmentation of cEPCs Author and Curator: Aviva Lev-Ari, PhD, RN

Vascular Medicine and Biology: Macrovascular Disease – Therapeutic Potential of cEPCs Curator and Author: Aviva Lev-Ari, PhD, RN

Repair damaged blood vessels in heart disease, stroke, diabetes and trauma: Cellular Reprogramming amniotic fluid-derived cells into Endothelial Cells

Reporter: Aviva Lev-Ari, PhD, RN

Stem cells in therapy

A possible light by Stem cell therapy in painful dark of Osteoarthritis” – Kartogenin, a small molecule, differentiates stem cells to chondrocyte, healthy cartilage cells Author and Reporter: Anamika Sarkar, Ph.D and Ritu Saxena, Ph.D.

Human embryonic pluripotent stem cells and healing post-myocardial infarctionAuthor: Larry H. Bernstein, MD

Stem cells create new heart cells in baby mice, but not in adults, study showsReporter: Aviva Lev-Ari, PhD, RN

Stem cells for the rescue of mitochondrial dysfunction in Parkinson’s diseaseReporter: Ritu Saxena, Ph.D.

Stem Cell Research — The Frontier is at the Technion in Israel Reporter: Aviva Lev-Ari, PhD, RN

Research articles by MA Gaballa, PhD

Harris DT, Badowski M, Nafees A, Gaballa MAThe potential of Cord Blood Stem Cells for Use in Regenerative Medicine. Expert Opinion in Biological Therapy 2007. Sept 7(9): 1131-22.

Furfaro E, Gaballa MADo adult stem cells ameliorate the damaged myocardium?. Human cord blood as a potential source of stem cells. Current Vascular Pharmacology 2007, 5; 27-44.

 

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Reporter: Aviva Lev-Ari, PhD, RN

 

CANCER BIOTHERAPEUTICS

ADCs, Multi-Specifics, Combined Therapies and Immunotherapy

Inaugural

TUESDAY , 5 NOVE MBER

»»PRE-CONFERENCE PLENARY SESION

16:55 Designing Receptor Binding Proteins with Highly Potent

Biological Function

Andreas Plückthun, Ph.D., Director and Professor, Biochemistry, University

of Zurich

Non-IgG molecules, unless armed with toxins or other effector units, are

usually thought to be limited in the biological responses they can elicit.

However, Designed Ankyrin Repeat Proteins (DARPins) are particularly

versatile, because of their favorable biophysical properties, and they can be

engineered into many formats. Using DARPins generated against members

of the EGFR family, and a combination of x-ray crystallography, signaling

studies, and in vivo experiments, it will be demonstrated how molecules

could be engineered to selectively induce apoptosis in tumors, and their

mechanism of action has been deduced. New intracellular sensors will be

described for such studies.

17:45 Immunotherapy with BiTE® Antibodies

Luis Borges, Ph.D., Scientific Director, Therapeutic Innovation Unit, Amgen, Inc.

BiTE® antibodies are potent bispecific single-chain antibodies that redirect T

cells to kill tumors. They engage a tumor target and a constant region of the

T cell receptor to recruit and activate polyclonal T cells to eliminate tumors.

They have demonstrated potent efficacy in various preclinical tumor models

and have now transitioned to clinical studies. Blinatumomab, a CD19xCD3

BiTE® antibody, is in clinical development and has shown high single-agent

response rates in patients with refractory or relapsed B-ALL and B-NHL.

18:30 End of Day

Wednesday, 6 November

07:45 Registration and Morning Coffee

08:30 Chairperson’s Opening Remarks

Jason Baum, Ph.D., Principal Scientist, Research, Merrimack Pharmaceuticals, Inc.

MULTI-SPECIFIC ANTIBODY PRODUCTS

08:35 Two-in-One Antibody Targeting EGFR and HER3 and Platform

Update

Germaine Fuh, Ph.D., Senior Scientist, Antibody Engineering, Genentech, Inc.

Mutation at the antigen binding sites of a mono-specific antibody may recruit a

second binding specificity such that each Fab arm exhibits dual binding function and

IgG with this dual action Fab (DAF) can be produced as conventional IgG. Proofof-

concept is a HER2/VEGF Two-in-One antibody; EGFR/HER3 Two-in-One DAF

antibody is in clinical phase II trial for treating epithelial cancer. The talk will cover the

generation and development of the EGFR/HER3 DAF antibody including preclinical

and clinical phase I data.

09:05 MM-141, a Bispecific Antibody Co-Targeting IGF-1R and Erbb3,

Overcomes Network Adaptation by Blocking Redundant Survival

Pathways

Jason Baum, Ph.D., Principal Scientist, Research, Merrimack Pharmaceuticals, Inc.

An integrated Network Biology approach was used to design and optimize MM-

141 to overcome limitations of first generation IGF-1R therapies by also blocking

heregulin-mediated compensation through ErbB3. MM-141 potentiates the activity

of both targeted therapies and chemotherapies through the combined inhibition

of PI3K/Akt/mTOR signaling as well as control over feedback loops triggered by

these agents.

09:35 Bispecific κλ-bodies for Selective Inhibition of CD47 in Cancer Cells

Nicolas Fischer, Ph.D., Head, Research, Novimmune SA

We have used our κλ-body platform to generate CD47-neutralizing bispecific

antibodies. These fully human antibodies are composed of a CD47-specific arm

and a targeting arm, specific to a tumor associated antigen (TAA). The preferential

neutralization of CD47 on TAA-expressing cancer cells should therefore show better

pharmacological properties and a broader therapeutic window as compared to nontargeted

anti-CD47 monoclonal antibodies. The presentation will also highlight how

light chain diversity can be exploited to create bispecific antibodies with favorable

manufacturability and stability profiles that facilitate their development path.

10:05 Sponsored Presentation (Opportunity Available)

10:35 Coffee Break in the Exhibit Hall with Poster Viewing

11:05 Targeting Tumor Microenvironmental Signals with Bispecific

Antibodies

Alessandro Angelini, Ph.D., David H. Koch Institute for Integrative Cancer Research,

Massachusetts Institute of Technology (MIT)

We have developed bispecific antibodies that locally contravene soluble signaling

factors that establish the supporting tumor microenvironment that enables tumor

survival and growth. Soluble factors such as VEGF, TGF-β, and IL-8 play a demonstrated

role in tumorigenesis, and enhanced interdiction of these signals within the tumor

should enhance the therapeutic index of cancer therapy.

11:35 Novel Multi-Targeting Antibody Mixtures: Mode of Action and

Advantages Over Other Approaches

Michael Kragh, Ph.D., Director, Antibody Pharmacology, Symphogen A/S

This talk will present the selection of antibodies against tumor-related antigens to

obtain synergistic combinations, the benefits of simultaneous targeting of multiple

receptors, and examine pan-HER (EGFR, HER2 and HER3) targeting to address

tumor heterogeneity and plasticity.

12:05 Sponsored Presentation (Opportunity Available)

12:35 Luncheon Presentations (Sponsorship Opportunities Available) or

Lunch on Your Own

ADVANCES WITH CANCER IMMUNOTHERAPY

14:00 Chairperson’s Remarks

Andrea van Elsas, CSO, BioNovion B.V.

14:05 Cancer Immunotherapy Using Immune Modulating Antibodies

Andrea van Elsas, CSO, BioNovion B.V.

Immune rejection of human cancer has been an elusive goal until recently. T cell

modulating antibodies targeting CTLA-4 and the PD-1 pathway induced clinically

meaningful responses and long-term benefit in patients with metastatic cancer.

Successful immune rejection can come with significant immune related adverse

events. Immune oncology agents do not directly tumor cells but treat the patient’s

immune cells. In this presentation, the discovery of immune modulating antibodies

and their translation into clinical success will be discussed.

14:35 Immunocytokines: A Novel Potent Class of Armed Antibody

Laura Gualandi, Ph.D., Philochem A.G.

Antibodies are effective tools that can deliver molecules with potent therapeutic

activity, such as Cytokines, to the tumor site, minimizing toxic effects. Aspects like

molecular format, valence and the chosen target antigen contribute to the efficacy of

the immunocytokines in vivo. Combinatory therapeutic strategies with other agents

have also been recently investigated. This talk will cover advanced preclinical and

clinical data on armed antibodies discovered and developed by the Philogen group.

15:05 NKTT320: A Humanized Monoclonal Antibody for Cancer

Immunotherapy

Robert Mashal, CEO, NKT Therapeutics

Activation of iNKT cells has been shown to have therapeutic effects both in

PEGSummitEurope.com 7

6-7 November 2013

preclinical models and in patients with cancer, and represents an important pathway

for the immunotherapy of cancer. iNKT cells have an invariant T cell receptor (iTCR).

NKT Therapeutics is developing NKTT320, a humanized monoclonal antibody which

specifically recognizes the iTCR present exclusively on iNKT cells, and has been

shown to activate iNKT cells both in vitro and in vivo.

15:35 Refreshment Break in the Exhibit Hall with Poster Viewing

16:15 Novel Tumor-Targeted, Engineered IL-2 Variant (IL-2v)-Based

Immunocytokines for Immunotherapy of Cancer

Ekkehard Moessner, Ph.D., Group Leader, Protein Engineering, pRED, Roche Glycart A.G.

A novel class of immunocytokines will be discussed that are based on Fc containing

and also on non-Fc containing building blocks. The IL2 component is optimized for

improved performance in tumor targeting. Enhancement of in vivo efficacy, when

combined with ADCC competent antibodies, will be discussed.

ANTIBODY-DRUG CONJUGATES AND PAYLOADS

16:45 Next-Generation ADCs: Enabling Higher Drug Loading,

Alternative Payloads, and Alternative Targeting Moieties

Timothy B. Lowinger, Ph.D., CSO, Mersana Therapeutics, Inc.

The application of polymers to antibody-drug conjugate (ADC) design can provide

numerous advantages, including significantly higher capacity for drug payload;

utilization of alternative payloads not suitable for direct conjugation; improvement of

physicochemical properties; and utilization of protein recognition scaffolds beyond

the commonly used IgGs. Examples of these benefits achieved using Mersana’s

polyacetal-based conjugation system to create next-generation ADCs

will be presented.

17:15 Problem Solving Roundtable Discussions

Table 1: Engineering of Bispecific Antibodies

Moderator: Nicolas Fischer, Ph.D., Head, Research, Novimmune SA

Table 2: Antibody-Drug Conjugates: Linkers and Payloads

Moderators: Robert Lutz, Ph.D., Vice President, Translational Research &

Development, ImmunoGen, Inc.

Timothy B. Lowinger, Ph.D., CSO, Mersana Therapeutics, Inc.

Table 3: Site-Specific Conjugation of ADCs

Moderator: Pavel Strop, Ph.D., Associate Research Fellow, Protein

Engineering, Rinat-Pfizer, Inc.

Table 4: Cancer Immunotherapy: Reaping the Benefits

Moderators: Andrea van Elsas, CSO, BioNovion B.V

Luis Borges, Ph.D., Scientific Director, Amgen, Inc.

Table 5: Cancer Biotherapeutics in the Clinic

Moderators: Jason Baum, Ph.D., Principal Scientist, Research, Merrimack

Pharmaceuticals, Inc.

Martine Piccart, M.D., Ph.D., Head, Medical Oncology, Jules Bordet

Institute; Chair, ESMO (European Society for Medical Oncology)

18:15 Networking Reception in the Exhibit Hall with Poster Viewing

19:15 End of Day One

Thursday, 7 November

07:45 Breakfast Presentation (Sponsorship Opportunity Available) or

Morning Coffee

08:30 Chairperson’s Remarks

Robert Lutz, Ph.D., Vice President, Translational Research & Development,

ImmunoGen, Inc.

08:35 A Universal Chemically Driven Approach for Constructing

Homogeneous ADCs

David Jackson, Ph.D., Principle Scientist, ADC Discovery, Igenica, Inc.

Current ADCs in clinical development are heterogeneous mixtures that differ in

both DAR (drugs/antibody) and their conjugation sites. Igenica has invented novel

site-specific linkers to enable the synthesis of homogeneous ADCs. The linkers

are compatible with a variety of drug payloads and can be applied to any antibody.

Homogeneous ADCs were synthesized using the novel linkers and compared to

heterogeneous ADCs made with conventional linkers. Analytical data and activity of

the ADCs in tumor models will be presented.

09:05 Location Matters: Site of Conjugation Modulates Stability and

Pharmacokinetics of Antibody-Drug Conjugates

Pavel Strop, Ph.D., Associate Research Fellow, Protein Engineering, Rinat- Pfizer, Inc.

To understand the role of conjugation site, we developed an enzymatic method for

site-specific antibody-drug conjugation. This allowed us to attach diverse compounds

at multiple positions and investigate how the site influences stability, toxicity, and

efficacy. We show that the conjugation site has significant impact on ADC stability

and pharmacokinetics in a species-dependent manner. With this method, it is

possible to produce homogeneous ADCs and tune their properties to maximize the

therapeutic window.

09:35 Development of Second Generation Duocarmycin ADCs with

Superior Therapeutic Window

Marion Blomenröhr, Ph.D., Program Manager Biopharmaceuticals, Synthon

Biopharmaceuticals

The first generation ADCs have successfully exploited the mAb-driven tumor cell

targeting for optimization of efficacy, but have failed to reduce off-target toxicities.

This presentation will highlight Synthon’s second generation Linker-Drug technology

and its complementarity with novel proprietary duocarmycin payloads yielding highly

stable and potent ADCs, with an improved in vivo therapeutic window.

10:05 Producing Better Antibody-Drug Conjugates Sponsored by

(ADCs) Using ThioBridge™ Conjugation

Antony Godwin, Ph.D., Director, Science & Technology, PolyTherics Ltd

Next-generation antibody-drug conjugates will be required to be less heterogeneous

and have better stability. PolyTherics has developed ThioBridge™ for improved

conjugation of a cytotoxic payload at the disulfides bonds of antibodies, antibody

fragments and other targeting proteins. With ThioBridge™, the resulting ADC

has the benefit of reduced heterogeneity, as the drug to antibody ratio is limited

to a maximum of 4 with little DAR 0 species. Stability is also enhanced, as unlike

single thiol conjugation approaches at disulfides, ThioBridge™ is not prone to

drug deconjugation reactions in serum. In vitro and in vivo data for mAb and Fab

conjugates with an established payload confirms specific binding and activity.

10:35 Coffee Break in the Exhibit Hall with Poster Viewing

»»PLENARY SESION

11:05 Medical Treatment of HER2 Positive Breast Cancer: Two

Decades of a Fascinating History and More to Come

Martine Piccart, M.D., Ph.D., Head, Medical Oncology, Jules Bordet

Institute; Chair, ESMO (European Society for Medical Oncology)

The talk will cover multiple aspects of anti-HER2 treatment in breast cancer.

It will present a summary of the clinical results obtained with trastuzumab

and several other anti-HER2 drugs in breast cancer (lapatinib, TDM1,

pertuzumab). Issues like the treatment duration, biomarkers of resistance

to treatment will be debated. Finally it will discuss future promising

research strategies: neoadjuvant trials, comparison between anti-HER2

agents, combinations of these drugs and functional imaging.

11:50 Antibody-Drug Conjugates: From Bench to Bedside and Back

Robert Lutz, Ph.D., Vice President, Translational Research & Development,

ImmunoGen, Inc.

Antibody-drug conjugates are emerging as an exciting approach to the

development of antibody-based therapeutics. The growing preclinical and

clinical experience with maytansinoid conjugates such as Kadcyla (T-DM1) is

leading to an enhanced understanding regarding critical attributes for target

antigens, antibodies, payloads and linkers. The translational knowledge

is being incorporated into research and development efforts for the next

generation of ADC candidates.

12:35 End of Cancer Biotherapeutics

http://www.pegsummiteurope.com/PEGS_Europe_Content.aspx?id=123176&libID=123124

 

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CD47: Target Therapy for Cancer

Author/Curator: Tilda Barliya

“A research team from Stanford University’s School of Medicine is now one step closer to uncovering a cancer treatment that could be applicable across the board in killing every kind of cancer tumor” (1). It appeared that their antibody-drug against the CD47 protein, enabled the shrinking of all tumor cells. After completing their animal studies the researchers now move into a human phase clinical trials. CD47 has been previously studied and evaluated for its role in multiple cells, some of this data however, is somewhat controversy. So where do we stand?

CD47

CD47 (originally named integrin-associated protein (IAP)) is a cell surface protein of the immunoglobulin (Ig) superfamily, which is heavily glycosylated and expressed by virtually all cells in the body and overexpressed in many types of cancer  including breast, ovarian, colon, prostate and others (3). CD47 was first recognized as a 50 kDa protein associated and copurified with the  Alpha-v-Beta-3 integrin in placenta and neutrophil granulocytes and later shown to have the capacity to regulate integrin function and the responsiveness of leukocytes to RGD-containing extracellular matrix proteins. CD47 has also been shown to be identical to the OA-3/OVTL3 antigen highly expressed on most ovarian carcinomas (4,5).

CD47 consists of an extracellular IgV domain, a five times transmembrane-spanning domain, and a short alternatively spliced cytoplasmic tail. In both humans and mice, the cytoplasmic tail can be found as four different splice isoforms ranging from 4 to 36 amino acids, showing different tissue expression patterns (3).

CD47 interactions (3, 6):

  • Thrombospondin-1 (TSP-1) – a secreted glycoprotein that plays a role in vascular development and angiogenesis. Binding of TSP-1 to CD47 influences several fundamental cellular functions including cell migration and adhesion, cell proliferation or apoptosis, and plays a role in the regulation of angiogenesis and inflammation.
  • Signal-regulatory protein-alpha (SIRPα) – an inhibitory transmembrane receptor present on myeloid cells. The CD47/SIRPα interaction leads to bidirectional signaling, resulting in different cell-to-cell responses including inhibition of phagocytosis, stimulation of cell-cell fusion, and T-cell activation.
  • Integrins – several membrane integrins, most commonly integrin avb3. These interactions result in CD47/integrin complexes that effect a range of cell functions including adhesion, spreading and migration

These interactions with multiple proteins and cells types create several important functions, which include:

  • Cell proliferation – cell proliferation is heavily dependent on cell type as both activation and loss of CD47 can result in enhanced proliferation. For example, activation of CD47 with TSP-1 in wild-type cells inhibits proliferation and reduces expression of stem cell transcription factors. In cancer cells however, activation of CD47 with TSP-1 increases proliferation of human U87 and U373 astrocytoma. it is likely that CD47 promotes proliferation via the PI3K/Akt pathway in cancerous cells but not normal cells (7).  Loss of CD47 allows sustained proliferation of primary murine endothelial cells and enables these cells to spontaneously reprogram to form multipotent embryoid body-like clusters (8).
  • Apoptosis – Ligation of CD47 by anti-CD47 mAbs was found to induce apoptosis in a number of different cell types (3). For example: Of the two SIRP-family members known to bind the CD47 IgV domain (SIRPα and SIRPγ), SIRPα as a soluble Fc-fusion protein does not induce CD47-dependent apoptosis, hile SIRPα or SIRPγ bound onto the surface of beads induces apoptosis through CD47 in Jurkat T cells and the myelomonocytic cell line U937.
  • Migration – CD47  role on cell migration was first demonstrated in neutrophils, these effects were shown to be dependent on avb3 integrins, which interact with and are activated by CD47 at the plasma membrane. In cancer, Blocking CD47 function has been shown to inhibit migration and metastasis in a variety of tumor models. Blockade of CD47 by neutralizing antibodies reduced migration and chemotaxis in response to collagen IV in melanomaprostate cancer and ovarian cancer-derived cells (9).
  • Angiogenesis – The mechanism of the anti-angiogenic activity of CD47 is not fully understood, but introduction of CD47 antibodies and TSP-1 have been shown to inhibit nitric oxide (NO)-stimulated responses in both endothelial and vascular smooth muscle cells (10). More so, CD47 signaling influences the SDF-1 chemokine pathway, which plays a role in angiogenesis (11). (12)
  • Inflammatory response – Interactions between endothelial cell CD47 and leukocyte SIRPγ regulate T cell transendothelial migration (TEM) at sites of inflammation. CD47 also functions as a marker of self on murine red blood cells which allows RBC to avoid phagocytosis. Tumor cells can also evade macrophage phagocytosis through the expression of CD47 (2, 13).

It appears that CD47 ligation induce different responses, depending on cell type and partner for ligation.

Therapeutic and clinical aspect of CD47 in human cancer:

CD47 is overexpressed in many types of human cancers  and its known function as a “don’t eat me” signal, suggests the potential for targeting the CD47-SIRPα pathway as a common therapy for human malignancies (2,13). Upregulation of CD47 expression in human cancers also appears to influence tumor growth and dissemination. First, increased expression of CD47 in several hematologic malignancies was found to be associated with a worse clinical prognosis, and in ALL to predict refractoriness to standard chemotherapies (13, 14-16). Second, CD47 was demonstrated to regulate tumor metastasis and dissemination in both MM and NHL (13, 17).

Efforts have been made to develop therapies inhibiting the CD47-SIRPα pathway, principally through blocking monoclonal antibodies directed against CD47, but also possibly with a recombinant SIRPα protein that can also bind and block CD47.

Figure 2

Chao MP et al. 2012 Combination strategies targeting CD47 in cancer

While monotherapies targeting CD47 were efficacious in several pre-clinical tumor models, combination strategies involving inhibition of the CD47-SIRPα pathway offer even greater therapeutic potential. Specifically, antibodies targeting CD47-SIRPα can be included in combination therapies with other therapeutic antibodies, macrophage-enhancing agents, chemo-radiation therapy, or as an adjuvant therapy to inhibit metastasis (13).

For example, anti-SIRPα antibody was found to potentiate  antibody-dependent cellular cytotoxicity (ADCC) mediated by the anti-Her2/Neu antibody trastuzumab against breast cancer cells (18).  CD47–SIRPα interactions and SIRPα signaling negatively regulate trastuzumab-mediated ADCC in vitro and antibody-dependent elimination of tumor cells in vivo

More so, chemo-radiation therapy-mediated upregulation of cell surface calreticulin may potentially augment the activity of anti-CD47 antibody. However, this approach may also lead to increased toxicity as cell surface calreticulin is expressed on non-cancerous cells undergoing apoptosis, a principle effect of chemo-radiation therapy (19).

Highlights:

  • Phagocytic cells, macrophages, regulate tumor growth through phagocytic clearance
  • CD47 binds SIRPα on phagocytes which delivers an inhibitory signal for phagocytosis
  • A blocking anti-CD47 antibody enabled phagocytic clearance of many human cancers
  • Phagocytosis depends on a balance of anti-(CD47) and pro-(calreticulin) signals
  • Anti-CD47 antibody synergized with an FcR-engaging antibody, such as rituximab

Summary

Evasion of immune recognition is a major mechanism by which cancers establish and propagate disease. Recent data has demonstrated that the innate immune system plays a key role in modulating tumor phagocytosis through the CD47-SIRPα pathway. Careful development of reagents that can block the CD47/SIRPα interaction may indeed be useful to treat many forms of cancer without having too much of a negative side effect in terms of inducing clearance of host cells. Therapeutic approaches inhibiting this pathway have demonstrated significant efficacy, leading to the reduction and elimination of multiple tumor types.

Dr. Weissman says: “We are now hopeful that the first human clinical trials of anti-CD47 antibody will take place at Stanford in mid-2014, if all goes wellClinical trials may also be done in the United Kingdom”. These clinical trials must be designed so that the data they generate will produce a valid scientific result!!!

REFERENCES

1. By Sara Gates:  Cancer Drug That Shrinks All Tumors Set To Begin Human Clinical Trials. http://www.huffingtonpost.com/2013/03/28/cancer-drug-shrinks-tumors_n_2972708.html

2. Willingham SB, Volkmer JP, Gentles AJ, Sahoo D, Dalerba P, Mitra SS, Wang J, Contreras-Trujillo H, Martin R, Cohen JD, Lovelace P, Scheeren FA, Chao MP, Weiskopf K, Tang C, Volkmer AK, Naik TJ, Storm TA, Mosley AR, Edris B, Schmid SM, Sun CK, Chua MS, Murillo O, Rajendran P, Cha AC, Chin RK, Kim D, Adorno M, Raveh T, Tseng D, Jaiswal S, Enger PØ, Steinberg GK, Li G, So SK, Majeti R, Harsh GR, van de Rijn M, Teng NN, Sunwoo JB, Alizadeh AA, Clarke MF, Weissman IL. The CD47-signal regulatory protein alpha (SIRPa) interaction is a therapeutic target for human solid tumors. Proc Natl Acad Sci U S A. 2012 Apr 24;109(17):6662-6667. http://www.pnas.org/content/early/2012/03/20/1121623109

3. Oldenborg PL. CD47: A Cell Surface Glycoprotein Which Regulates Multiple Functions of Hematopoietic Cells in Health and Disease. ISRN Hematology Volume 2013 (2013), Article ID 614619, 19 pages.  http://www.hindawi.com/isrn/hematology/2013/614619/

4. G. Campbell, P. S. Freemont, W. Foulkes, and J. Trowsdale, “An ovarian tumor marker with homology to vaccinia virus contains an IgV- like region and multiple transmembrane domains,”Cancer Research, vol. 52, no. 19, pp. 5416–5420, 1992. http://cancerres.aacrjournals.org/content/52/19/5416.long

5. L. G. Poels, D. Peters, Y. van Megen et al., “Monoclonal antibody against human ovarian tumor-associated antigens,” Journal of the National Cancer Institute, vol. 76, no. 5, pp. 781–791, 1986. http://www.ncbi.nlm.nih.gov/pubmed/3517452

6. CD47. Wikipedia. http://en.wikipedia.org/wiki/CD47

7. Sick E, Boukhari A, Deramaudt T, Rondé P, Bucher B, André P, Gies JP, Takeda K (February 2011). “Activation of CD47 receptors causes proliferation of human astrocytoma but not normal astrocytes via an Akt-dependent pathway”. Glia 59 (2): 308–319. http://www.ncbi.nlm.nih.gov/pubmed/21125662

8. Kaur S, Soto-Pantoja DR, Stein EV, Liu C, Elkahloun AG, Pendrak ML, Nicolae A, Singh SP, Nie Z, Levens D, Isenberg JS, Roberts DD.  “Thrombospondin-1 Signaling through CD47 Inhibits Self-renewal by Regulating c-Myc and Other Stem Cell Transcription Factors”Sci Rep 2013: 3: 1673. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3628113/

9. Shahan TA, Fawzi A, Bellon G, Monboisse JC, Kefalides NA. “Regulation of tumor cell chemotaxis by type IV collagen is mediated by a Ca(2+)-dependent mechanism requiring CD47 and the integrin alpha(V)beta(3)”. J. Biol. Chem 2000. 275 (7): 4796–4802. http://www.jbc.org/content/275/7/4796

10. Isenberg JS, Ridnour LA, Dimitry J, Frazier WA, Wink DA, Roberts DD. “CD47 is necessary for inhibition of nitric oxide-stimulated vascular cell responses by thrombospondin-1”. J. Biol. Chem  2006. 281 (36): 26069–26080.  http://www.jbc.org/content/281/36/26069

11. Smadja DM, d’Audigier C, Bièche I, Evrard S, Mauge L, Dias JV, Labreuche J, Laurendeau I, Marsac B, Dizier B, Wagner-Ballon O, Boisson-Vidal C, Morandi V, Duong-Van-Huyen JP, Bruneval P, Dignat-George F, Emmerich J, Gaussem P. “Thrombospondin-1 is a plasmatic marker of peripheral arterial disease that modulates endothelial progenitor cell angiogenic properties”. Arterioscler. Thromb. Vasc. Biol  2011. 31 (3): 551–559. http://atvb.ahajournals.org/content/31/3/551

12. G. D. Grossfeld, D. A. Ginsberg, J. P. Stein et al., “Thrombospondin-1 expression in bladder cancer: association with p53 alterations, tumor angiogenesis, and tumor progression,” Journal of the National Cancer Institute 1997 vol. 89, no. 3, pp. 219–227. http://www.scopus.com/record/display.url?eid=2-s2.0-18744423089&origin=inward&txGid=9C86356DDB0B6816ACCBF90F9CA44E92.WlW7NKKC52nnQNxjqAQrlA%3a2

13. Chao MP, Weissman IL, Majeti R. “The CD47-SIRPα pathway in cancer immune evasion and potential therapeutic implications”Curr. Opin. Immunol 2012. 24 (2): 225–32. http://www.sciencedirect.com/science/article/pii/S095279151200012Xhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3319521/

14. Majeti R, Chao MP, Alizadeh AA, Pang WW, Jaiswal S, Gibbs KD, Jr, van Rooijen N, Weissman IL. Cd47 is an adverse prognostic factor and therapeutic antibody target on human acute myeloid leukemia stem cells. Cell. 2009;138(2):286–299. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2726837/

15. Chao MP, Alizadeh AA, Tang C, Jan M, Weissman-Tsukamoto R, Zhao F, Park CY, Weissman IL, Majeti R. Therapeutic antibody targeting of cd47 eliminates human acute lymphoblastic leukemia.Cancer Res. 2011;71 (4):1374–1384. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3041855/

16. Chao MP, Alizadeh AA, Tang C, Myklebust JH, Varghese B, Gill S, Jan M, Cha AC, Chan CK, Tan BT, Park CY, et al. Anti-cd47 antibody synergizes with rituximab to promote phagocytosis and eradicate non-hodgkin lymphoma. Cell. 2010;142(5):699–713. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2943345/

17. Chao MP, Tang C, Pachynski RK, Chin R, Majeti R, Weissman IL. Extranodal dissemination of non-hodgkin lymphoma requires cd47 and is inhibited by anti-cd47 antibody therapy. Blood.2011;118(18):4890–4901. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3208297/

18. Zhao XW, van Beek EM, Schornagel K, Van der Maaden H, Van Houdt M, Otten MA, Finetti P, Van Egmond M, Matozaki T, Kraal G, Birnbaum D, et al. Cd47-signal regulatory protein-alpha (sirpalpha) interactions form a barrier for antibody-mediated tumor cell destruction. Proc Natl Acad Sci U S A.2011;108(45):18342–18347. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3215076/

19. Obeid M, Tesniere A, Ghiringhelli F, Fimia GM, Apetoh L, Perfettini JL, Castedo M, Mignot G, Panaretakis T, Casares N, Metivier D, et al. Calreticulin exposure dictates the immunogenicity of cancer cell death. Nat Med. 2007;13(1):54–61. http://www.ncbi.nlm.nih.gov/pubmed/17187072

Other related articles on this Open Access Online Scientific Journal include the following:

I. By: Larry Bernstein MD. Treatment for Metastatic HER2 Breast Cancer https://pharmaceuticalintelligence.com/2013/03/03/treatment-for-metastatic-her2-breast-cancer/

II. By: Tilda Barliya PhD. Colon Cancer.  https://pharmaceuticalintelligence.com/2013/04/30/colon-cancer/

III. By: Ritu Saxena PhD. In focus: Triple Negative Breast Cancer. https://pharmaceuticalintelligence.com/2013/01/29/in-focus-triple-negative-breast-cancer/

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