Dr. Gelzleichter: Evaluation of Carcinogenic Risk for Biotechnology

Transcript Dr. Gelzleichter: Evaluation of Carcinogenic Risk for Biotechnology

Evaluation of Carcinogenic Risk for Biotechnology-Derived Therapeutics

Tom Gelzleichter September 27 th , 2012

Topics

1. Limitations on utility of standard rodent bioassays for biologics 2. Historical approaches for risk assessment of biologics 3. 2011 revisions to ICH S6 4. Examples of revised approach 5. How will these changes impact risk communication?

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

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 Limitations in data interpretation and lack of validation limit utility ©2012, Genentech

Challenges with Nongenotoxic Drugs:

What We’ve Learned From Risk Evaluation of Immunosuppressive Agents

Human Neoplasms Associated with 13 Immunosuppressive Drugs Type

Lymphoma Squamous Cell Carcinoma Kaposi Sarcoma Urologic Melanoma Multiple Source: Bugelski et al.(2010) Int. J. Toxicol. 29(5) 435-66

Drugs

Dexamethasone, prednisone, busulfan, azathioprine, methotrexate, mycophenolate, cyclosporin A, tacrolimus Prednisone, busulfan, azathioprine, methotrexate, mycophenolate, cyclosporin A, tacrolimus Dexamethasone, prednisone, busulfan, azathioprine, methotrexate, mycophenolate, cyclosporin A Prednisone, azathioprine, mycophenolate, cyclosporin A, tacrolimus mycophenolate cyclophosphamide ©2012, Genentech

Two year bioassay results for immunosuppresive drugs Drug

Abatacept Dexamethasone Prednisone Busulfan Cyclophosphamide Azathioprine Leflunomide Methotrexate Mycophenolate Cyclosporine Tacrolimus sirolimus everolimus

Rat 2 yr

Neg multiple Lymphoma and squamous Neg Neg Neg Neg Neg Neg Neg

Mouse 2 yr

Lymphomas and mammary tumors (MLV/MMT virus) Neg Thymic and ovarian multiple Lymphoma, hemangioendothelioma Lymphoma and lung Neg Neg Neg Neg Lymphoma and liver 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 No

• Further studies in relevant model • Incorporate sensitive indices of proliferation into chronic studies • If biologically active and nonimmunogenic

consider

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

32 FDA-Licensed MAb’s 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 Ustekinumab Ofatumumab Denosumab Tocilizumab (Atlizumab ) Belimumab Brentuximab vedotin Ipilimumab ( MDX 101 ) ©2012, Genentech Year Licensed by FDA 1986 1994 1997 1997 1998 1998 1998 1998 2000 2001 2002 2002 2002 2003 2004 2004 2004 2006 2006 2006 2007 2008 2009 2009 2009 2009 2010 2010 2011 2011 2011 Target T cell CD3 Receptor inhibition of glycoprotein IIb/IIIa IL-2R α receptor (CD25) CD20 IL-2R α receptor (CD25) inhibition of TNF α signaling an epitope of the RSV F protein ErbB2 CD33 CD52 inhibition of TNF α signaling CD11a CD20 CD20 VEGF epidermal growth factor receptor immunoglobulin E (IgE) alpha-4 ( α4) integrin, epidermal growth factor receptor VEGF-A Complement system protein C5 inhibition of TNF α signaling IL-1 β TNF-alpha inihibitor anti-IL12/IL23 CD20 RANK Ligand inhibitor Anti- IL-6R inihibition of B- cell activating factor CD30 blocks CTLA-4 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 drug related effects noted no no no no no • Two Sponsors conducted trials that 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 Two year carc studies have not been performed… But tumors ID’ed in chronic tox studies Hypothical risk stated in label glargine (insulin analog), ocreotide (somatostatin analog), teriparatide (parathyroid hormone analog), IGF-1, gonadotropin releasing hormone, exenatide, liraglutide (incretin mimetic), pulmozyme (rhDNAse), abatacept aspart, glusine, and lispro (insulin analogs), calcitonin, pamlinitide (amylin hormone analog), 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

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

Risk considered low

Risk unclear

• Consider studies as discussed in ICH S6, 1997)

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 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 Positive predictivity: 63% Negative predictivity: 88% False negatives: 6% 2 yr Bioassay

Chronic Tox (rat)

+ + 25 15 5 35 Reddy, deGeorge, et al., 2010.

Vet. Path

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

Posited Strategy for Labeling Revisions (Proposed for SOT Discussion Only: Not Formal FDA Position)

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

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

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