Nor Cal SOT Evaluation of Carcinogenic Risk for Biotechnology-Derived Therapeutics Tom Gelzleichter September 27th, 2012 2012, Genentech Topics 1. 2. 3. 4. 5. Limitations on utility of standard rodent bioassays for biologics Historical approaches for risk assessment of biologics 2011 revisions to ICH S6 Examples of revised approach How will these changes impact risk communication? 2012, Genentech Main Objective of Carcinogenesis Testing for
Pharmaceuticals A product-specific assessment of carcinogenic potential is used to communicate risk and provide input to the risk management plan along with labeling proposals, clinical monitoring, post-marketing surveillance 2012, Genentech 2 year bioassays in general have limited utility for all chemical classes Interpretation difficult due to: Lack of known negative controls (IARC only classifies one chemical as probably not carcinogenic in humans) Susceptibility determined by genotype, sex and test conditions Examples: cigarette smoke, arsenic, benzene were challenging to find rodent models that gave positive results Lack of concordance across sexes, species (rarely are tumors found in all 4 genotypes i,.e., rat/mouse/M/F) Inter-rodent predictivity (rat:mouse) 70-75% Validation efforts have been heavily skewed towards certain chemical classes (plus, nearly all have been genotoxicants) Poor concordance for immunotoxicants, some hormones Poor reproducibility (only 57% concordance when repeated) Positivity rate is extremely high
In NTP studies, 68% of tested chemicals are positive in at least one of the 4 genotypes 40% of marketed pharmaceuticals and food additives are positive 2012, Genentech Why are Chronic Rodent Bioassays Still Used? Most known human carcinogens are positive in at least one of the 4 genotypes tested, when evaluated at MTD Only 5-10% of positives are strictly rodent carcinogens i.e, has some positive predictive value However, rate of false positives poorly understood Limitations of the assay limit the utility Typically used to inform label, informed consent Rarely will regulatory agencies use this data in isolation for decision-making 2012, Genentech What About Biologics? Rarely are long term studies in rodents feasible for biologics due to antigenicity concerns or lack of binding Lack of validation data Limited data for nongenotoxic carcinogens Virtually no validation efforts with large molecules (e.g., Tg-AC
transgenic model) Known lack of concordance for immunosuppressive agents, many hormones Surrogate molecules: Discouraged given difficulties in verifying that surrogate accurately reflects the biology of clinical candidate Other data: Data from in class or related drugs Transgenic/ko Xenograft studies 2012, Genentech Limitations in data interpretation and lack of validation limit utility Challenges with Nongenotoxic Drugs: What Weve Learned From Risk Evaluation of Immunosuppressive Agents 2012, Genentech Human Neoplasms Associated with 13 Immunosuppressive Drugs
Type Drugs Lymphoma Dexamethasone, prednisone, busulfan, azathioprine, methotrexate, mycophenolate, cyclosporin A, tacrolimus Squamous Cell Carcinoma Prednisone, busulfan, azathioprine, methotrexate, mycophenolate, cyclosporin A, tacrolimus Kaposi Sarcoma Dexamethasone, prednisone, busulfan, azathioprine, methotrexate, mycophenolate, cyclosporin A Urologic Prednisone, azathioprine, mycophenolate, cyclosporin A, tacrolimus
Melanoma mycophenolate Multiple cyclophosphamide Source: Bugelski et al.(2010) Int. J. Toxicol. 29(5) 435-66 2012, Genentech Two year bioassay results for immunosuppresive drugs Drug Rat 2 yr Mouse 2 yr Abatacept - Lymphomas and mammary tumors (MLV/MMT virus)
Azathioprine Lymphoma and squamous Lymphoma, hemangioendothelioma Leflunomide Neg Lymphoma and lung Methotrexate Neg Neg Mycophenolate Neg Neg
Cyclosporine Neg Neg Tacrolimus Neg Neg sirolimus Neg Lymphoma and liver everolimus Neg Neg Of the 5 positives, 4 are known genotoxicants
Poor concordance with known human risks Only 2 correctly predict specific tumor risks 2012, Genentech ICH Guidance for Biologics (Original ICH S6, 1997) Standard carc bioassays are generally inappropriate for biotech drugs When there is a concern, a variety of approaches may be considered to evaluate risk In case where product is biologically active and nonimmunogenic and other studies have not provided sufficient information to assess risk, then consider a singe rodent bioassay 2012, Genentech For Products that Support or Induce Proliferation (ICH S6, 1997) Evaluate/review receptor expression in malignant and normal cells Is there evidence that can stimulate growth of normal or malignant cells? Cause for concern? Yes Further studies in relevant model Incorporate sensitive indices of
proliferation into chronic studies If biologically active and nonimmunogenic consider long term assay 2012, Genentech No In vitro evaluations may be sufficient Question: Given the limitations of chronic bioassays and ICH guidance, what type of carc studies have been conducted for biologics? Answer: In reality, very few chronic studies have been conducted that have actually impacted product labels 2012, Genentech 32 FDA-Licensed MAbs to date: Two sponsors have conducted preclinical studies that impacted label Generic Name Muromonab-CD3 Abcixumab
Daclizumab Rituximab Basiliximab Infliximab Palivizumab Trastuzumab Gemtuzumab Alemtuzumab Adalimumab Efalizumab Ibritumomab Tositumomab Bevacizumab Cetuximab Omalizumab Natalizumab Panitumumab Ranibizumab Eculizumab Certolizumab pegol Canakinumab Golimumab Year Licensed by FDA
Target T cell CD3 Receptor inhibition of glycoprotein IIb/IIIa IL-2R receptor (CD25) CD20 IL-2R receptor (CD25) inhibition of TNF- signaling an epitope of the RSV F protein ErbB2 CD33 CD52 inhibition of TNF- signaling CD11a CD20 CD20 VEGF epidermal growth factor receptor immunoglobulin E (IgE) CD20 RANK Ligand inhibitor LT Carc studies on label? no no
no no no no no no no no no no no no no no no xenograft models of a4+ cell lines: no drug related impact no no no no no no Decreased host defense to tumors with surrogate; knockout
mice susceptible to tumors [Data not from Sponsor-run trials] 7 month cyno tumorigenicity data included in label - no drugrelated effects noted no Anti- IL-6R inihibition of B- cell activating factor CD30 no no no blocks CTLA-4 no alpha-4 (4) integrin, epidermal growth factor receptor VEGF-A Complement system protein C5 inhibition of TNF- signaling IL-1
impacted label One label impacted by published literature reports (ustekinumab) Label Claims for Non-MAb Therapeutics Label Claim 2 yr studies in one or two species glargine (insulin analog), ocreotide (somatostatin analog), teriparatide (parathyroid hormone analog), IGF-1, gonadotropin releasing hormone, exenatide, liraglutide (incretin mimetic), pulmozyme (rhDNAse), abatacept Two year carc studies have not been performed But tumors IDed in chronic tox studies aspart, glusine, and lispro (insulin analogs), calcitonin, pamlinitide (amylin hormone analog), Hypothical risk stated in label asparaginase (alkylating agent)
Two year carc studies in animals have not been performed. humulin, novolin, lente, ultralente, Exubera, detemir, genotropin, humantrope, norditropin, norIVitropin, nutropin, omnitrope, protropin, siazen, serostim, valtropin, iplex, bioclate, helixate, kogenate, recombinate, reFacto, BeneFIX, ceprotin, aldurazyme, elaprase, naglazyme, fabrazyme, aralast, prolastin, lactaid, arco-lase, cotazym, creon, donnazyme, pancrease, viokase, zymase, adagen octagam, albumarc, albumin, albuminar, albuRx, albutein, flexbumin, buminate, plasbumin, neupogen, neulasta, leukine, neumega, Gonal-F, Follistim, ovidrel, luveris, infergen, roferon-A, Pegasys, Intron A, Peg-Intron, Alferon N, Avonex, rebif, betaseron, actimmune, proleukin, activase, retavase, TNKase, abbokinase, NovoSeven, Xigris, kepivance, regranex, granulex, natrecor, botox, myoblock collagenase, xiaflex, santyl, amphadase, hydase, vitrase, hylenex, oncaspar, elitek, refludan, angiomax, streptase, eminase, antril, kinaret, thioglobulin, fuzeon, somavert, crofab, digifab, ontak, 2012, Genentech New ICH S6 Revision (ICH S6 R1, June 2011) To better inform risk, a new paradigm has been implemented by ICH
When an assessment is warranted (i.e., chronic dosing, appropriate patient population, etc.) a weight of evidence approach is now advocated More emphasis on post-marketing surveillance 2012, Genentech What Can this Include? Assessment of risk based on published literature and internal data Clinical Market surveillance Human epidemiology Genetic diseases Polymorphisms Class effects Mechanistic data
Is there impact on pathways known to be associated with malignancy risk Immunosuppression, chronic inflammation Downstream signaling through pathways associated with risk Transgenic models KO models Animal disease models Xenograft models In vitro data Chronic tox data Alternative data (lifetime phenotyping, labeling for proliferation) 2012, Genentech Recommendations per ICH S6 R1, 2011 Outcome of Weight Based Assessment Cause for concern Hazard best addressed by product labeling and risk management practices Sponsor can propose additional studies to mitigate concern
2012, Genentech Risk unclear Consider studies as discussed in ICH S6, 1997) Risk considered low Additional rodent bioassays not warranted Example: PCSK9 Inhibitor Class FDA has provided guidance to all sponsors that are targeting PCSK9 (LDL-c lowering therapies) Recommends a Thorough Carcinogenicity Assessment as described in ICH S6 (R1) Requests that it is submitted early in development program (e.g., EOP2) Includes formal evaluation of immunosuppressive potential (recommends 12 week study in cynos in combo w/ statin) Specific interest in NK cell activity, CD8+ T cell cytolytic activity Includes evaluation of impact on bile acid synthesis evidence of immunosuppression and/or a sustained increase in bile
acid secretion and/or intestinal bile acid load would be disclosed in the label as potential cancer risks 2012, Genentech Example: Studies to Mitigate Cause for Concern GLP-1 analogs and C cell tumors Rodent bioassays identified increases in C-cell tumors Follow-up in vitro studies evaluated GLP-1 expression in rodent, monkey and human C cells GLP-1 expression was much lower in humans, monkeys relative to rodents GLP-1 agonists stimulated measurable C-cell calcitonin release in rodents but not human or monkey cells Calcitonin levels evaluated in 5000 patients treated for up to two years with no evidence of increase Longitudinal studies have not identified causal association between GLP-1 analogs and C cell pathology However, FDA AERS database supports a potential risk of thyroid cancer with exenatide Current label (liraglutide): In mice a dose-related increase in benign thyroid C-cell adenomas was seen In rats a treatment-related increase in benign thyroid C-cell adenomas was seen Human relevance of thyroid C-cell tumors in mice and rats is unknown and could not be determined by clinical studies or nonclinical studies 2012, Genentech
Example: Class Effect Labeling 13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility A carcinogenicity study was not conducted with belatacept. However, a murine carcinogenicity study was conducted with abatacept (a more active analog in rodents) to determine the carcinogenic potential of CD28 blockade. Weekly subcutaneous injections of 20, 65, or 200 mg per kg of abatacept were associated with 2012, Genentech increases in the incidence of malignant lymphomas (all doses) and mammary gland tumors. Utility of General Tox Study Results Predictivity of 6- or 12 month general tox studies for 2 yr bioassay (rats) Histology evaluation (+ = increase in hyperplasia, hypertrophy, and atypical cellular foci (e.g., multinucleated cells, dysplasia, etc.) 2 yr rat bioassay (+ = increase in significant increase in tumors) 80 pharmacuticals evaluated (all FDA approved, sufficient rat data available for eval) 30 rat carcinogens, 50 noncarcinogens Chronic Tox (rat) Positive predictivity: 63% Negative predictivity: 88% False negatives: 6% 2 yr
Bioassay + - + 25 5 - 15 35 Reddy, deGeorge, et al., 2010. Vet. Path. 47(4) 614-629 2012, Genentech Where is carcinogenic risk communicated currently in label? Boxed warning Section 5: Warnings and Precautions Immunosuppression or Malignancies
Section 6: Adverse Events Malignancies Section13: Nonclinical Toxicology 13.1 carcinogenesis must state whether long term studies in animals have been performed to evaluate the carcinogenic potential and, if so, the species and results any precautionary statement on these topics must include practical, relevant advice to the prescriber on the significance of these animal findings. Human data suggesting that the drug may be carcinogenic as described in the Warning and Precautions section, must not be included in this subsection of the labeling. Section17: Patient Counseling Information Source: Dan Mellon, FDA SOT 2012 Presentation . 2012, Genentech Posited Strategy for Labeling Revisions (Proposed for SOT Discussion Only: Not Formal FDA Position) 2012, Genentech 2012, Genentech
2012, Genentech Bottom Line: Changes in risk communication in not only product labels but informed consent documents, investigator brochures, etc. are anticipated but regulatory agencies have yet to address what these changes will look like 2012, Genentech Summary Historically, classical lifetime rodent bioassays have had limited utility for malignancy risk assessment for biologics and have had little impact on informing product labels ICH has implemented new paradigm: Weight based assessment that incorporates clinical, preclinical and mechanistic data It remains to be seen how these risk assessments will be communicated in product labels 2012, Genentech
Page 28 Thank You Slide Credits: Dan Mellon(FDA) Heather Taylor (Genentech) 2009, Genentech / Proprietary information Please do not copy, distribute or use without prior written consent. 2012, Genentech
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