Posts Tagged ‘Spinal muscular atrophy’

Novartis uses a ‘dimmer switch’ medication to fine-tune gene therapy candidates

Reporter: Amandeep Kaur, BSc., MSc.

Using viral vectors, lipid nanoparticles, and other technologies, significant progress has been achieved in refining the delivery of gene treatments. However, modifications to the cargo itself are still needed to increase safety and efficacy by better controlling gene expression.

To that end, researchers at Children’s Hospital of Philadelphia (CHOP) have created a “dimmer switch” system that employs Novartis’ investigational Huntington’s disease medicine branaplam (LMI070) as a regulator to fine-tune the quantity of proteins generated from a gene therapy.

According to a new study published in Nature, the Xon system altered quantities of erythropoietin—which is used to treat anaemia associated with chronic renal disease—delivered to mice using viral vectors. The method has previously been licenced by Novartis, the maker of the Zolgensma gene therapy for spinal muscular atrophy.

The Xon system depends on a process known as “alternative splicing,” in which RNA is spliced to include or exclude specific exons of a gene, allowing the gene to code for multiple proteins. The team used branaplam, a small-molecule RNA-splicing modulator, for this platform. The medication was created to improve SMN2 gene splicing in order to cure spinal muscular atrophy. Novartis shifted its research to try the medication against Huntington’s disease after a trial failure.

A gene therapy’s payload remains dormant until oral branaplam is given, according to Xon. The medicine activates the expression of the therapy’s functional gene by causing it to splice in the desired way. Scientists from CHOP and the Novartis Institutes for BioMedical Research put the dimmer switch to the exam in an Epo gene therapy carried through adeno-associated viral vectors. The usage of branaplam increased mice Epo levels in the blood and hematocrit levels (the proportion of red blood cells to whole blood) by 60% to 70%, according to the researchers. The researchers fed the rodents branaplam again as their hematocrit decreased to baseline levels. The therapy reinduced Epo to levels similar to those seen in the initial studies, according to the researchers.

The researchers also demonstrated that the Xon system could be used to regulate progranulin expression, which is utilised to treat PGRN-deficient frontotemporal dementia and neuronal ceroid lipofuscinosis. The scientists emphasised that gene therapy requires a small treatment window to be both safe and effective.

In a statement, Beverly Davidson, Ph.D., the study’s senior author, said, “The dose of a medicine can define how high you want expression to be, and then the system can automatically ‘dim down’ at a pace corresponding to the half-life of the protein.”

“We may imagine scenarios in which a medication is used only once, such as to control the expression of foreign proteins required for gene editing, or only on a limited basis. Because the splicing modulators we examined are administered orally, compliance to control protein expression from viral vectors including Xon-based cassettes should be high.”

In gene-modifying medicines, scientists have tried a variety of approaches to alter gene expression. For example, methyl groups were utilised as a switch to turn on or off expression of genes in the gene-editing system CRISPR by a team of researchers from the Massachusetts Institute of Technology and the University of California, San Francisco.

Auxolytic, a biotech company founded by Stanford University academics, has described how knocking down a gene called UMPS could render T-cell therapies ineffective by depriving T cells of the nutrition uridine. Xon could also be tailored to work with cancer CAR-T cell therapy, according to the CHOP-Novartis researchers. The dimmer switch could help prevent cell depletion by halting CAR expression, according to the researchers. According to the researchers, such a tuneable switch could help CRISPR-based treatments by providing “a short burst” of production of CRISPR effector proteins to prevent undesirable off-target editing.

Source: https://www.fiercebiotech.com/research/novartis-fine-tunes-gene-therapy-a-huntington-s-disease-candidate-as-a-dimmer-switch?mkt_tok=Mjk0LU1RRi0wNTYAAAF-q1ives09mmSQhXDd_jhF0M11KBMt0K23Iru3ZMcZFf-vcFQwMMCxTOiWM-jHaEvtyGOM_ds_Cw6NuB9B0fr79a3Opgh32TjXaB-snz54d2xU_fw

Other Related Articles published in this Open Access Online Scientific Journal include the following:

Gene Therapy could be a Boon to Alzheimer’s disease (AD): A first-in-human clinical trial proposed

Reporter: Dr. Premalata Pati, Ph.D., Postdoc


Top Industrialization Challenges of Gene Therapy Manufacturing

Guest Authors: Dr. Mark Szczypka and Clive Glover


Dysregulation of ncRNAs in association with Neurodegenerative Disorders

Curator: Amandeep Kaur


Cancer treatment using CRISPR-based Genome Editing System 

Reporter: Irina Robu, PhD


CRISPR-Cas9 and the Power of Butterfly Gene Editing

Reporter: Madison Davis


Gene Editing for Exon 51: Why CRISPR Snipping might be better than Exon Skipping for DMD

Reporter: Aviva Lev-Ari, PhD, RN


Gene Editing: The Role of Oligonucleotide Chips

Curators: Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN


Cause of Alzheimer’s Discovered: protein SIRT6 role in DNA repair process – low levels enable DNA damage accumulation

Reporter: Aviva Lev-Ari, PhD, RN


Delineating a Role for CRISPR-Cas9 in Pharmaceutical Targeting

Author & Curator: Larry H. Bernstein, MD, FCAP


Brain Science

Larry H Bernstein, MD, FCAP, Curator


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Liver Toxicity halts Clinical Trial of IAP Antagonist for Advanced Solid Tumors

Curator: Stephen J. Williams, Ph.D.

UPDATED 8/12/2022

Athough not related to IAP Antagonists this update does report 2 deaths from IDILI or idiosynchratic drug induced liver injury from a gene therapy trial using an AAV (adeno associated virus) targeting the disease spinal muscular atrophy.  Please see below after reading about IDILI.


A recent press release on FierceBiotech reported the FDA had put a halt on a phase 1 study for advanced refractory solid tumors and lymphomas of Curis Inc. oral inhibitor of apoptosis (IAP) antagonist CUDC-427.  The FDA placed the trial on partial clinical hold following reports of a death of a patient from severe liver failure.  The single-agent, dose escalation Phase 1 study was designed to determine the maximum tolerated dose and recommended doses for a Phase 2 trial. The press release can be found at:


According to the report one patient with breast cancer that had metastasized to liver, lungs, bone, and ovaries developed severe hepatotoxicity as evidenced by elevated serum transaminase activities (AST and ALT) and hyper-billirubinemia.  Serum liver enzyme activities did not attenuate upon discontinuation of CUDC-427.  This was unlike prior experience to the CUDC-427 drug, in which decreased hepatic function was reversed upon drug discontinuation.  The patient died from liver failure one month after discontinuation of CUDC-427.

It was noted that no other patient had experienced such a serious, irreversible liver dysfunction.

Although any incidence of hepatotoxicity can be cause for concern, the incidence of IDIOSYNCRATIC IRREVERSIBLE HEPATOTOXICITY warrants a higher scrutiny.

Four general concepts can explain toxicity profiles and divergences between individuals:

  1. Toxicogenomics: Small differences in the genetic makeup between individuals (such as polymorphisms (SNP) could result in differences in toxicity profile for a drug.  This ais a serious possibility as only one patient presented with such irreversible liver damage
  2. Toxicodynamics:  The toxicologic effect is an extension of the pharmacologic mechanism of action (or  lack thereof: could there have been alternate signaling pathways activated in this patient or noncanonical mechanism)
  3. Toxicokinetic:  The differences in toxicological response due to differences in absorption, distribution, metabolism, excretion etc. (kinetic parameters)
  4. Idiosyncratic: etiology is unknown; usually a minority of adverse effects


Since there is not enough information to investigate toxicogenomic or toxicokinetic mechanisms for this compound, the rest of this post will investigate the possible mechanisms of hepatotoxicity due to IAP antagonists and clues from other clinical trials which might shed light on a mechanism of toxicity (toxicodynamic) or idiosyncratic events.

Therefore this post curates the current understanding of drug-induced liver injury (DILI), especially focusing on a type of liver injury referred to as idiosyncratic drug-induced liver injury (IDILI) in the context of:

  1. Targeted and newer chemotherapies such as IAP antagonists
  2. Current concepts of mechanisms of IDILI including:

i)        Inflammatory responses provoked by presence of disease

ii)      Cellular stresses, provoked by disease, uncovering NONCANONICAL toxicity pathways

iii)    Pharmacogenomics risk factors of IDILI

Eventually this post aims to stimulate the discussion: 

  • Given inflammation, genetic risk factors, and cellular stresses (seen in clinical setting) have been implicated in idiosyncratic drug-induced liver injury from targeted therapies, should preclinical hepatotoxicity studies also be conducted in the presence of the metastatic disease?
  • Does inflammation and cellular stress from clinical disease unmask NONCANONICAL pharmacologic and/or toxicological mechanisms of action?

Classification of types of Cellular Liver injury:  A listing of types of cellular injury is given for review

I.     Hepatic damage after Acute Exposure

A. Cytotoxic (Necrotic):  irreversible cell death characterized by loss of cell membrane integrity, intracellular swelling, nuclear shrinkage (pyknosis) and eventual cytoplasmic breakdown of nuclear DNA (either by a process known as karyolysis or karyorhexus) localized inflammation as a result of release of cellular constituents.  Intracellular ATP levels are commonly seen in necrotic death.  Necrosis, unlike apoptosis, does not require a source of ATP.  A nice review by Yoshihide Tsujimoto describing and showing (by microscopy) the  differences between apoptosis and necrosis can be found here.

B. Cholestatic:  hepatobiliary dysfunction with bile stasis and accumulation of bile salts.  Cholestatic injury can result in lipid (particularly cholesterol) accumulation in cannicular membranes resulting in decreased permeability of the membrane, hyperbillirubinemia and is generally thought to result in metabolic defects.

C. Lipid Peroxidation: free radical generation producing peroxide of cellular lipids, generally resulting in a cytotoxic cell death

II.     Hepatic damage after Chronic Exposure

A. Chirrotic: Chronic morphologic alteration of the liver characterized by the presence of septae of collagen distributed throughout the major portion of the liver; Forms fibrous sheaths altering hepatic blood flow, resulting in a necrotic process with scar tissue; Alteration of hepatic metabolic systems.

B. Carcinogenesis

III. Idiosyncratic Drug Induced Liver Injury

The aforementioned mechanisms of hepatotoxicity are commonly referred to as the “intrinsic” (or end target-organ) toxicity mechanisms.  Idiosyncratic drug-induced liver injury (IDILI) is not well understood but can be separated into allergic and nonallergic reactions.  Although the risk of acute liver failure associated with idiosyncratic hepatotoxins is low (about 1 in ten thousand patients) there are more than 1,000 drugs and herbal products associated with this type of toxic reaction. Idiosyncratic drug induced liver failure usually gets a black box warning from the FDA. Idiosyncratic drug-induced liver injury differs from “intrinsic” toxicity in that IDILI:

  • Happens in a minority of patients (susceptible patients)
  • Not reproducible in animal models
  • Not dose-dependent
  • Variable time of onset
  • Variable liver pathology (not distinctive lesions)
  • Not related to drug’s pharmacologic mechanism of action (trovafloxacin IDILI vs. levofloxacin)

A great review in Perspectives in Pharmacology written by Robert Roth and Patricia Ganey at Michigan State University explains these differences between intrinsic and idiosyncratic drug-induced hepatotoxicity[1] (however authors do note that there are many similarities between the two mechanisms).    It is felt that drug sensitivity (allergic) and inflammatory responses (nonallergic) may contribute to the occurrence of IDILI.  For instance lipopolysaccharide (LPS) form bacteria can potentiate acetaminophen toxicity.  In fact animal models of IDILI have been somewhat successful:

  • co-treatment of rats and mice with nontoxic doses of trovafloxacin (casues IDILI in humans) and LPS resulted in marked hepatotoxicity while no hepatotoxicity seen with levofloxacin plus LPS[2]
  • correlates well with incidence of human IDILI (adapted from a review Inflammatory Stress and Idiosyncratic Hepatotoxicity: Hints from Animal Models (in Pharmacology Reviews)[3].  Idiosyncratic injury damage has been reported for diclofenac, halothane, and sulinac.  These drugs also show hepatotoxicity in the LPS model for IDILI.
  • Roth and Ganey suggest the reason why idiosyncratic hepatotoxicity is not seen  in most acute animal toxicity studies is that, in absence of stress/inflammation  IDILI occurrence is masked by lethality but stress/inflammation shifts increases sensitivity to liver injury at a point before lethality is seen


Figure.  Idiosyncratic toxic responses of the liver.    In the absence of stress and/or genetic factors, drug exposure may result in an idiosyncratic liver injury (IDILI) at a point (or dose) beyond the therapeutic range and lethal exposure for that drug.  Preclinical studies, usually conducted at sublethal doses, would not detect DILI .  Stress and/or genetic factors sensitize the liver to toxic effects of the drug (synergism) and DILI is detected at exposure levels closer to therapeutic range.  Note IDILI is not necessarily dose-dependent but cellular stress (like ROS or inflammation) may expose NONCANONICAL mechanisms of drug action or toxicity which result in IDILI. Model adapted from Roth and Ganey.

What Stress factors contribute to IDILI?

Various stresses including inflammation from bacterial, viral infections ,inflammatory cytokines  and stress from reactive oxygen (ROS) have been suggested as mechanisms for IDILI.

  1. Inflammation/Cytokines (also discussed in other sections of this post):  Inflammation has long been associated with human cases of DILI.    Many cytokines and inflammatory mediators have been implicated including TNFα, IL7, TGFβ, and IFNϒ (viral infection) leading some to conclude that serum measurement of cytokines could be a potential biomarker for DILI[4].  In addition, ROS (see below) is generated from inflammation and also considered a risk factor for DILI[5].
  2. Reactive Oxygen (ROS)/Reactive Metabolites: Oxidative stress, either generated from reactive drug metabolites or from mitochondrial sources, has been shown to be involved in apoptotic and necrotic cell death.  Both alterations in the enzymes involved in the generation of and protection from ROS have been implicated in increased risk to DILI including (as discussed further) alterations in mitochondrial superoxide dismutase 2 (SOD2) and glutathione S-transferases.  Both ROS and inflammatory cytokines can promote JNK signaling, which has been implicated in DILI[6].

Dr. Neil Kaplowitz suggested that we:

“develop a unifying hypothesis that involves underlying genetic or acquired mitochondrial abnormalities as a major determinant of susceptibility for a number of drugs that target mitochondria and cause DILI. The mitochondrial hypothesis, implying gradually accumulating and initially silent mitochondrial injury in heteroplasmic cells which reaches a critical threshold and abruptly triggers liver injury, is consistent with the findings that typically idiosyncratic DILI is delayed (by weeks or months), that increasing age and female gender are risk factors and that these drugs are targeted to the liver and clearly exhibit a mitochondrial hazard in vitro and in vivo. New animal models (e.g., the Sod2(+/-) mouse) provide supporting evidence for this concept. However, genetic analyses of DILI patient samples are needed to ultimately provide the proof-of-concept”[7].

Clin Infect Dis. 2004 Mar 38(Supplement 2) S44-8, Figure 1

Clin Infect Dis. 2004 Mar 38(Supplement 2) S44-8, Figure 3

Figures. Mechanisms of Drug-Induced Liver Injury and Factors related to the occurrence of  DILI (used with permission from Oxford Press; reference [7])

To this end, Dr. Brett Howell and other colleagues at the Hamner-UNC Institute for Drug Safety Sciences (IDSS) developed an in-silico model of DILI ( the DILISym™ model)which is based on  depletion of cellular ATP and reactive metabolite formation as indices of DILI.

Have there been Genetic Risk Factors identified for DILI?

Candidate-gene-associated studies (CGAS) have been able to identify several genetic risk factors for DILI including:

  1. Uridine Diphosphate Glucuronosyltransferase 2B7 (UGT2B7): variant increased susceptibility to diclofenac-induced DILI
  2. Adenosine triphosphate-binding cassette C2 (ABCC2) variant ABCC-24CT increased susceptibility to diclofenac-induced DILI
  3. Glutathione S-transferase (GSTT1): patients with a double GSTT1-GSTM1 null genotype had a significant 2.7 fold increased risk of DILI from nonsteroidal anti-inlammatory agents, troglitazone and tacrine.  GSTs are involved in the detoxification of phase 1 metabolites and also protect against cellular ROS.

Although these CGAS confirmed these genetic risk factors,  Stefan Russman suggests a priori genome-wide association studies (GWAS) might provide a more complete picture of genetic risk factors for DILI as CGAS is limited due to

  1. Candidate genes are selected based on current mechanisms and knowledge of DILI so genetic variants with no known knowledge of or mechanistic information would not be detected
  2. Many CGAS rely on analysis of a limited number of SNP and did not consider intronic regions which may control gene expression

A priori GWAS have the advantage of being hypothesis-free, and although they may produce a high number of false-positives, new studies of genetic risk factors of ximelagatran, flucioxaciliin and diclofenac-induced liver injury are using a hybrid approach which combines the whole genome and unbiased benefits of GWAS with the confirmatory and rational design of CGAS[8-10].

Even though idiosyncratic DILI is rare, the severity, unpredictable onset, and unknown etiology and risk factors have prompted investigators such as Stefan Russmann from University Hospital Zurich and Ignazio Grattagliano from University of Bari to suggest:

Identification of risk factors for rare idiosyncratic hepatotoxicity requires special networks that contribute to data collection and subsequent identification of environmental as well as genetic risk factors for clinical cases of idiosyncratic DILI[11].

Therefore, a DILI network project (DILIN) had been developed to collect samples and detailed genetic and clinical data on IDILI cases from multiple medical centers.  The project aims to identify the upstream and downstream genetic risk factors for IDILI[12].  Please see a SlideShare presentation here of the goals of the DILI network project.

Drs Colin Spraggs and Christine Hunt had reviewed possible genetic risk factors of DILI seen with various tyrosine kinase inhibitors (TKIs) including Lapatinib (Tykerb/Tyverb©, a dual inhibitor of  HER2/EGFR heterodimer) and paopanib (Votrient©; a TKI that targets VEGFR1,2,3 and PDGFRs)[13].

From a compilation of studies:

  • Elevation in serum bilirubin during treatment with lapatinib and pazopanib are associated with UGT1A1 polymorphism related to Gilbert’s syndrome (a clinically benign syndrome)
  • Anecdotal evidence shows that polymorphisms of lapatinib and pazopanib metabolizing enzymes may contribute to differences seen in onset of DILI
  • Pazopanib-induced elevations of ALT correlate with HFE variants, suggesting alterations in iron transport may predispose to DILI
  • Strong correlations between lapatinib-induced DILI and class II HLA locus suggest inflammatory stress response important in DILI

Note that these clinical findings were not evident from the preclinical tox studies. According to the European Medicines Agency assessment report for Tykerb states: “the major findings in repeat dose toxicity studies were attributed to lapatinib pharmacology (epithelial effect in skin and GI system.  The toxic events occurred at exposures close to the human exposure at the recommended dose.  Repeat-dose toxicity studies did not reveal important safety concerns than what would be expected from the mode of action”.

However, it should be noted that in high dose repeat studies in mice and rats, severe lethality was seen with hematologic, gastrointestinal toxicities in combination with altered blood chemistry parameters and yellowing of internal organs.

IAP Antagonists, Mechanism of Action, and Clinical Trials:

A few IAP antagonists which are in early stage development include:

  • Norvatis IAP Inhibitor LCL161: at 2012 San Antonia Breast Cancer Symposium, a phase 1 trial in triple negative breast cancer showed promising results when given in combination with paclitaxel.
  • Ascenta Therapeutics IAP inhibitor AT-406 in phase 1 in collaboration with Debiopharm S.A. showed antitumor efficacy in xenograft models of breast, pancreatic, prostate and lung cancer. The development of this compound is described in a paper by Cai et. al.

National Cancer Institute sponsored trials using antagonists of IAPs include

  • Phase II Study of Birinapant for Advanced Ovarian, Fallopian Tube, and Peritoneal Cancer (NCI-12-C-0191). Principle Investigator: Dr. Christina Annunziata. See the protocol summary. More open trials for this drug are located here.  Closed trials including safety studies can be found here.
  • A Phase 1 non-randomized dose escalation study to determine maximum tolerated dose (MTD) and characterize the safety for the TetraLogic compound TL32711 had just been completed. Results have not been published yet.
  • Closed Clinical trials with the IAP antagonist HGS1029 in advanced solid tumors determined that weekly i.v. administration of HGS1029 reported a safety issue for primary outcome measures

A great review on IAP proteins and their role as regulators of apoptosis and potential targets for cancer therapy [14] can be found as a part of a Special Issue in Experimental Oncology “Apoptosis: Four Decades Later”.  Human IAPs (inhibitors of apoptosis) consist of eight proteins involved in cell death, immunity, inflammation, cell cycle, and migration including:

In general, IAP proteins are directly involved in inhibiting apoptosis by binding and directly inhibiting the effector cysteine protease caspases (caspase 3/7) ultimately responsible for the apoptotic process [15].  IAPs were actually first identified in baculoviral genomes because of their ability to suppress host-cell death responses during viral infection [16]. IAP proteins are often overexpressed in cancers [17].

Apoptosis is separated into two pathways, defined by the initial stress or death signal and the caspases involved:

  1. Extrinsic pathway: initiated by TNFα and death ligand FasLigand;  involves caspase-8; process inhibited by IAP1/2
  2. Intrinsic pathway: initiated by DNA damage, irradiation, chemotherapeutics; mitochondrial pathway involving caspase 9 and cytochrome c release from mitochondria; mitochondria also releases SMAC/DIABLO, which binds and inhibits XIAP (XIAP inhibits the Intrinsic apoptotic pathway.



Intrinsic and Extrinsic pathways of apoptosis. Figure photocredit (wikidot.com)

The Curis IAP antagonist (and others) is a SMAC small molecule mimetic. It is interesting to note [18, 19] that IAP antagonists can result in death by

  • Apoptosis: an IAP antagonist in presence of competent TNFα signaling
  • Necrosis: seen with IAP inhibitors in cells with altered TNFα signaling or with presence of caspase inhibitors

IAPs are also involved in the regulation of signaling pathways such as:

NF-ΚB signaling pathway

NF-ΚB is a “rapid-acting” transcription factor which has been found to be overexpressed in various cancers.  Under most circumstances NF-ΚB translocation to the nucleus results in transcription of genes related to cell proliferation and survival.  NF-ΚB signaling is broken down in two pathways

  1. Canonical:  Canonical pathway can be initiated (for example in inflammation) when TNF-α binds its receptors activating  death domains (TRADD)
  2. Noncanonical: since requires new protein synthesis takes longer than canonical signaling.  Can be initiated by other TNF like ligands like CD40

IAP1/2 is a negative regulator of the noncanonical NF-ΚB signaling pathway by promoting proteosomal degradation of the TRAF signaling complex. A wonderfully annotated list of NF-ΚB target genes can be found on the Thomas Gilmore lab site at Boston University at http://www.bu.edu/nf-kb/gene-resources/target-genes/ .

NF-ΚB has been considered a possible target for chemotherapeutic development however Drs. Veronique Baud and Michael Karin have pondered the utility of IAP antagonists as a good target in their review: Is NF-ΚB a good target for cancer therapy?: Hopes and pitfalls [20].  The authors discuss issues such that IAP antagonism induced both the classical and noncanonical NF-ΚB pathway thru NIK stabilization, resulting in stabilization of NF-ΚB signaling and thereby undoing any chemotherapeutic effect which would be desired.

AKT signaling

IAPs have been shown to interact with other proteins including a report that SIAP regulates AKT activity and caspase-3-dependent cleavage during cisplatin-induced apoptosis in human ovarian cancer cells and could be another mechanism involved in cisplatin resistance[21].   In addition there have been reports that IAPs can regulate JNK and MAPK signaling.

Therefore, IAPs are involved in CANONICAL and NONCANONICAL pathways.

IAPs can Regulate Pro-Inflammatory Cytokines

A recent 2013 JBC paper [22]showed that IAPs and their antagonists can regulate spontaneous and TNF-induced proinflammatory cytokine and chemokine production and release

  • IAP required for production of multiple TNF-induced proinflammatory mediators
  • IAP antagonism decreased TNF-mediated production of chemokines and cytokines
  • But increased spontaneous release of chemokines

In addition Rume Damgaard and Mads Gynd-Hansen have suggested that IAP antagonists may be useful in treating inflammatory diseases like Crohn’s disease as IAPs regulate innate and acquired immune responses[23].

Toxicity profiles of IAP antagonists

NOTE: In a paper in Toxicological Science from 2012[24], Rebecca Ida Erickson form Genentech reported on the toxicity profile of the IAP antagonist GDC-0152 from a study performed in dogs and rats. A dose-dependent toxicity profile from i.v. administration was consistent with TNFα-mediated toxicity with

  • Elevated plasma cytokines and an inflammatory leukogram
  • Increased serum transaminases
  • Inflammatory infiltrate and apoptosis/necrosis in multiple tissues

In a related note, a similar type of fatal idiosyncratic hepatotoxicity was reported in a 62 year-old man treated with the Raf kinase inhibitor sorafenib for renal cell carcinoma[25]: Fatal case of sorafenib-associated idiosyncratic hepatotoxicity in the adjuvant treatment of a patient with renal cell carcinoma; Case Report  in BMC Cancer.

At week four after initiation of sorafenib treatment, the patient noticed increasing fatigue, malaise, gastrointestinal discomfort and abdominal rash.  Although treatment was discontinued, jaundice developed and blood test revealed an acute hepatitis with

  • Elevated serum ALT
  • Elevated serum alkaline phosphatase
  • Increased prothrombin time
  • Increased LDH

…elevated levels seen in the case with the aforementioned IAP antagonist.  Autopsy revealed

  • Lobular hepatitis
  • Mononuclear cell infiltrate
  • Hepatocyte necrosis

These findings are in line with a drug-induced inflammation and IDILI. In addition to hepatotoxicity, renal insufficiency developed in this patient. The authors had suggested the death was probably due to “an idiosyncratic allergic reaction to sorafenib manifesting as hepatotoxicity with associated renal impairment”.  The authors also noted that genome wide association studies of idiosyncratic drug-induced liver injury support involvement of major histocompatibility complex (MHC) polymorphisms[26].  MHC involvement has also been associated with lapatanib and pazopanib hepatotoxicity [27, 28].

Curis has been involved in another novel oncology therapeutic, a first in class.

Last year Roche and Genentech had won approval for a Hedgehog pathway inhibitor vismodegib for treatment of advanced basal cell carcinoma (reported at FierceBiotech©). Vismodegib was initially developed in collaboration with Curis, Inc.  The hedgehog signaling pathway, which controls the function of Gli factors (involved in stem cell differentiation), is overactive in advanced basal cell carcinoma as well as other cancer types.

As an additional reference, the FDA National Center for Toxicological Research has developed THE LIVER TOXICITY KNOWLEDGE BASE (LTKB).

“The LTKB is a project designed to study drug-induced liver injury (DILI). Liver toxicity is the most common cause for the discontinuation of clinical trials on a drug, as well as the most common reason for an approved drug’s withdrawal from the marketplace. Because of this, DILI has been identified by the FDA’s Critical Path Initiatives as a key area of focus in a concerted effort to broaden the agency’s knowledge for better evaluation tools and safety biomarkers.”

A nice SlideShow of Toxicity of Targeted Therapies can be found here: http://www.slideshare.net/RashaHaggag/toxicities-of-targeted-therapies

Also please note that ALL GENES in this article are linked to their GENECARD 

UPDATED 8/12/2022


Zolgensma Gene Therapy Linked to 2 Deaths in SMA Patients, Novartis Reports

The 2 deaths, due to acute liver failure, occurred in patients treated in Kazakhstan and Russia.

Two children with spinal muscular atrophy (SMA) have died after being treated with onasemnogene abeparvovec (Zolgensma; Novartis) from acute liver failure, a known safety risk of the therapy.1

Novartis has updated the FDA and other regulatory agencies in countries that Zolgensma is approved in, including Russia and Kazakhstan, where the deaths occurred. The company will also update the labeling of Zolgensma to include the deaths.

“While this is important safety information, it is not a new safety signal and we firmly believe in the overall favorable risk/benefit profile of Zolgensma, which to date has been used to treat more than 2300 patients worldwide across clinical trials, managed access programs, and in the commercial setting,” Novartis said in an emailed statement to BioPharma Dive.2

Zolgensma’s labeling includes the risk of liver injury and instructs clinicians to assess liver function before treatment and to manage liver enzyme counts with steroid treatment. The 2 deaths occurred 5 to 6 weeks after the one-time infusion and 1 to 10 days after corticosteroid treatment was tapered, according to an initial report from Stat News.1

READ MORE: Zolgensma Shows Efficacy in SMA With 3 SMN2 Copies

An FDA advisory committee meeting that took place last fall identified risks of adeno associated virus (AAV) gene therapies including, specifically, Zolgensma.2 The committee recommended caution, but nothing that would hinder gene therapy development.

Zolgensma, which was approved in the US in May 2019, just recently demonstrated further positive data from SPR1NT (NCT03505099), a phase 3 multicenter, single-arm trial on its effect in presymptomatic children with SMA in 2 articles published in Nature Medicine.3,4

All children in both the type 1 and type 2 cohorts achieved the ability to independently sit and most achieved other age-appropriate milestones including standing and walking. None of the children in the study required respiratory support or nutritional support, and there were no serious treatment-related adverse events observed.

“The robust data from both the 2- and 3-copy SPR1NT cohorts are being published together for the first time, further supporting the significant and clinically meaningful benefit of Zolgensma in presymptomatic babies with SMA,” Shephard Mpofu, MD, SVP, chief medical officer, Novartis Gene Therapies, said in a previous statement.5 “When treated with Zolgensma prior to the onset of symptoms, not only did all 29 patients enrolled in SPR1NT survive, but were thriving—breathing and eating on their own, with most even sitting, standing, and walking without assistance.”


1. Silverman E. Novartis reports two children died from acute liver failure after treatment with Zolgensma gene therapy. STAT. August 11, 2022. https://www.statnews.com/pharmalot/2022/08/11/novartis-zolgensma-liver-failure-gene-therapy-death/

2. Pagliarulo N. Novartis reports deaths of two patients treated with Zolgensma gene therapy. BioPharma Dive. August 12, 2022. https://www.biopharmadive.com/news/novartis-zolgensma-patient-death-liver-injury/629542/

3. Strauss KA, Farrar MA, Muntoni F, et al. Onasemnogeneabeparvovec for presymptomatic infants with two copies of SMN2 at risk for spinal muscular atrophy type 1: the Phase III SPR1NT trial. Nat Med. Published online June 17, 2022. doi:10.1038/s41591-022-01866-42

4. Strauss KA, Farrar MA, Muntoni F, et al. Onasemnogeneabeparvovec for presymptomatic infants with three copies of SMN2 at risk for spinal muscular atrophy: the Phase III SPR1NT trial. Nat Med. Published online June 17, 2022.doi: 10.1038/s41591-022-01867-3

5. Novartis announces Nature Medicine publication of Zolgensma data demonstrating age-appropriate milestones when treating children with SMA presymptomatically. News release. Novartis. June 17, 2022. https://firstwordpharma.com/story/5597735



1.            Roth RA, Ganey PE: Intrinsic versus idiosyncratic drug-induced hepatotoxicity–two villains or one? The Journal of pharmacology and experimental therapeutics 2010, 332(3):692-697.

2.            Waring JF, Liguori MJ, Luyendyk JP, Maddox JF, Ganey PE, Stachlewitz RF, North C, Blomme EA, Roth RA: Microarray analysis of lipopolysaccharide potentiation of trovafloxacin-induced liver injury in rats suggests a role for proinflammatory chemokines and neutrophils. The Journal of pharmacology and experimental therapeutics 2006, 316(3):1080-1087.

3.            Deng X, Luyendyk JP, Ganey PE, Roth RA: Inflammatory stress and idiosyncratic hepatotoxicity: hints from animal models. Pharmacological reviews 2009, 61(3):262-282.

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5.            Schwabe RF, Brenner DA: Mechanisms of Liver Injury. I. TNF-alpha-induced liver injury: role of IKK, JNK, and ROS pathways. American journal of physiology Gastrointestinal and liver physiology 2006, 290(4):G583-589.

6.            Seki E, Brenner DA, Karin M: A liver full of JNK: signaling in regulation of cell function and disease pathogenesis, and clinical approaches. Gastroenterology 2012, 143(2):307-320.

7.            Kaplowitz N: Drug-induced liver injury. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2004, 38 Suppl 2:S44-48.

8.            Kindmark A, Jawaid A, Harbron CG, Barratt BJ, Bengtsson OF, Andersson TB, Carlsson S, Cederbrant KE, Gibson NJ, Armstrong M et al: Genome-wide pharmacogenetic investigation of a hepatic adverse event without clinical signs of immunopathology suggests an underlying immune pathogenesis. The pharmacogenomics journal 2008, 8(3):186-195.

9.            Aithal GP, Ramsay L, Daly AK, Sonchit N, Leathart JB, Alexander G, Kenna JG, Caldwell J, Day CP: Hepatic adducts, circulating antibodies, and cytokine polymorphisms in patients with diclofenac hepatotoxicity. Hepatology 2004, 39(5):1430-1440.

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13.          Spraggs CF, Xu CF, Hunt CM: Genetic characterization to improve interpretation and clinical management of hepatotoxicity caused by tyrosine kinase inhibitors. Pharmacogenomics 2013, 14(5):541-554.

14.          de Almagro MC, Vucic D: The inhibitor of apoptosis (IAP) proteins are critical regulators of signaling pathways and targets for anti-cancer therapy. Experimental oncology 2012, 34(3):200-211.

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Other articles on the site about Toxicology and Pharmacology of New Classes of Cancer Chemotherapy include:

FDA Guidelines For Developmental and Reproductive Toxicology (DART) Studies for Small Molecules

Gamma Linolenic Acid (GLA) as a Therapeutic tool in the Management of Glioblastoma

DNA Methultransferases – Implications to Epigenetic Regulation and Cancer Therapy Targeting: James Shen, PhD

Molecular Profiling in Cancer Immunotherapy: Debraj GuhaThakurta, PhD

AT13148 – A Novel Oral Multi-AGC Kinase Inhibitor Has Potent Antitumor Activity

Targeting Mitochondrial-bound Hexokinase for Cancer Therapy

Breast Cancer, drug resistance, and biopharmaceutical targets

Ubiquitin-Proteosome pathway, Autophagy, the Mitochondrion, Proteolysis and Cell Apoptosis: Part III

Ubiquinin-Proteosome pathway, autophagy, the mitochondrion, proteolysis and cell apoptosis

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Reporter: Prabodh Kandala, PhD.

Zebrafish, popular as aquarium fish, now have an important place in research labs as a model organism for studying human diseases.

At the 2012 International Zebrafish Development Conference, held June 20-24 in Madison, Wisconsin, numerous presentations highlighted the utility of the zebrafish for examining the basic biological mechanisms underlying human disorders and identifying potential treatment approaches for an impressive array of organ and systemic diseases.

Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), while rarely fatal, can have a substantial negative impact on an individual’s quality of life due to abdominal pain, diarrhea, vomiting, bleeding, and severe cramps. The causes of this chronic inflammatory disorder are largely unknown and existing treatments, usually anti-inflammatory drugs, are often not effective. In addition, IBD is often associated with increased risk of developing intestinal cancer.

Researchers from the University of Pittsburgh are using zebrafish to study the biological mechanisms that lead to intestinal inflammation, as often seen in IBD, providing additional understanding that may allow development of better therapies. Prakash Thakur, a research associate working with Nathan Bahary, M.D., Ph.D., described a mutant zebrafish strain that shows many pathological characteristics similar to IBD, including inflammation, abnormal villous architecture, disorganized epithelial cells, increased bacterial growth and high numbers of dying cells in the intestine. “Most of the hallmark features of the disease are seen in this mutant. We are utilizing this fish as a tool to unravel fundamental mechanisms of intestinal pathologies that may contribute to intestinal inflammatory disorders, ” Mr. Thakur said.

The fish have a genetic mutation that disrupts de novo synthesis of an important signaling molecule called phosphatidylinositol (PI). The lack of de novo PI synthesis, Mr. Thakur and his colleagues found, leads to chronic levels of cellular stress, particularly the endoplasmic reticum stress and, ultimately, inflammation. Drugs or other interventions targeting the cellular stress response pathway, rather than just inflammation, helped restore a healthy intestinal structure and increase cell survival in the fish intestine, suggesting this mechanism as a potential therapeutic target for patients with inflammatory disorders, including IBD.

Doxorubicin-Induced Heart Failure

Doxorubicin is a potent chemotherapy drug used to treat many types of cancer, including leukemia, lymphoma, carcinoma, soft tissue sarcoma, and bladder, breast, lung, stomach and ovarian cancers. Unfortunately, drug-induced cardiomyopathy is a common side effect and can lead to heart failure in cancer patients, not only during treatment, but months or years later.

“We hope to identify some drug which only blocks the side effect of doxorubicin but preserves the therapeutic effect,” said Yan Liu, Ph.D., a postdoctoral researcher working in Dr. Randall Peterson’s lab at the Massachusetts General Hospital.

Dr. Liu developed a zebrafish model of doxorubicin-induced cardiomyopathy. The fish experience heart failure within two days of treatment with symptoms similar to those seen in humans, including fewer heart muscle cells, ventricular collapse, and ineffective heartbeats.

The researchers used the model to screen through thousands of potential drug compounds and identified two — visnagin and diphenylurea — that both improved cardiac function and reduced doxorubicin-induced cell death in the heart. Importantly, both compounds specifically protected heart tissue, but not tumor cells, from the toxic effects of doxorubicin. Both seem to act through the suppression of a particular signaling pathway, the c-Jun N-terminal kinase pathway, in the heart cells but not tumor cells.

Dr. Liu also reported promising preliminary results with mice showing reduced cell death and improved cardiac function, indicating that these compounds may also be active in mammals and giving hope for therapies that specifically treat doxorubicin’s side effects without negating its anti-tumor activity.

Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a group of progressive neurodegenerative diseases that affect the nerves in the spinal cord that control muscles, leading to weakness, movement difficulties, poor posture, and trouble breathing and eating.

SMA is linked to mutations in a specific motor neuron survival gene, SMN1. Though mouse studies have reported immature and ineffective synaptic connections between motor neurons and muscles, little is known about the molecular mechanisms leading to those problems or how they might be fixed.

Graduate student Kelvin See, working with Associate Professor Christoph Winkler, Ph.D., at the National University of Singapore used zebrafish with activity-sensitive fluorescence to provide a visual readout of motor neuron activation. They confirmed that low SMN1 levels are associated with low neuronal influx of calcium ions, which play a critical role in triggering neurotransmitter release and thus stimulating the muscles. With their zebrafish model, Mr. See and Dr. Winkler also identified another gene with a similar effect, neurexin, which is important in synaptic structure but had never been implicated in SMA.

In a surprise discovery, the researchers found they could use the same sensor to see activation of a neighboring cell type called Schwann cells. “This gives us the unique opportunity to look at the role of SMN1 not just in motor neurons but also in the surrounding tissue,” said Mr. See.

They saw reduced excitability in Schwann cells also, suggesting that a full understanding of SMA will require a broader view of the affected cell populations. Their results provide several new insights into the fundamental processes disrupted in SMA.

Acute T-cell Lymphoblastic Leukemia and Lymphoma (T-ALL/T-LBL)

Human acute T-cell lymphoblastic leukemias (ALL) and lymphomas (LBL) have high relapse rates in pediatric patients and high mortality rates in adults. Hui Feng, M.D., Ph.D., currently at the Pharmacology Department and Center for Cancer Research at Boston University School of Medicine, is using a zebrafish model of leukemia to search for promising targets for new molecular treatments for these diseases.

To date, studies have identified several biological pathways involved in ALL and LBL, all with a known oncogene in common called c-Myc. However, Myc is so common, involved in regulating more than 15 percent of all genes, that it is very hard to study.

“Because this is a huge list of downstream targets, it is very challenging to predict which genes in the pathway to target to treat Myc-related cancers,” said Dr. Feng.

In work performed in collaboration with Thomas Look, M.D., at the Dana-Farber Cancer Institute, Dr. Feng is combining the power of zebrafish genetics with human clinical studies to hone in on potential genes of interest.

Using a fish strain that reliably develops T-cell lymphoma by two months of age, they identified a novel gene called DLST that is involved in metabolism and energy production in cells. Evidence from human cancer cell lines and patients indicate that abnormally high levels of the protein may be involved in the human disease as well.

Reducing DLST activity in the fish significantly delayed tumor progression and growth, suggesting it is a promising target for developing new therapies for ALL and LBL.



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