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Preclinical Safety Assessment Studies to Support Manufacturing Process Changes for Vectibix

Barbara Mounho, Ph.D., D.A.B.T.Amgen, Inc.

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Presentation

• Information presented taken from:– Vectibix, European Public Assessment Report,

CHMP, 2007 – Vectibix, FDA Review, Application Number

12514, approval 09/27/2006– Vectibix Prescribing Information, Thousand

Oaks, CA: Amgen, Inc; 2008– www.Vectibix.com– literature

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Overview

• Epidermal Growth Factor Receptor (EGFr) and Vectibix® – biology and rationale for targeting the EGFr pathway in cancer

• Manufacturing Process Change – what changed and when in the clinical development program

• Comparability Assessment Exercise• Summary

– what did we learn from the comparability toxicology studies– approach today

• applying a science-based decision tree in determining if toxicology study needed in comparability package

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Overview of the EGFr • EGFr (HER1 or ErB1) Belongs to the ErbB Family of Cell

Surface Receptors– 170 Kd transmembrane glycoprotein– extracellular ligand-binding domain (621 AAs)– intracellular tyrosine kinase domain (542 AAs)

• Expressed in Various Normal Cells of Epithelial Origin– skin, lung, GI tract, liver

• Endogenous Ligands:- EGF - amphiregulin - epiregulin- TGF - betacellulin - heparin-binding EGF

• Pivotal Role in Maintenance of Cellular Function & Survival- cell proliferation & differentiation - migration/motility- inhibition of apoptosis - enhanced cell survival

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Role of EGFr Pathway in Cancer

EGF TGF

Ligand Binding

Dimerization of the receptor- homodimer- heterodimer with other ErbB

family coreceptors

HeterodimerHomodimer

ATPATP ATP

High

affinity

binding

Ligand Binding and Dimerization Results in Tyrosine Kinase Activation

- ATP binding- Autophosphorylation of the receptor tyrosine kinase - Activation signal transduction pathways

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Role of EGFr in Cancer • Expression of EGFr Has Been Observed in Human Cancers

– colorectal– head and neck

• EGFr Expression Correlates With: – poor response to treatment– disease progression– poor survival

• In Normal Cells, the EGFr Signal is Strictly Regulated• Malignant Cells, the EGFr Signal is Inappropriately Activated• EGFr Pathway Activation in Tumor Cells Mediates

Several Processes– cell survival and proliferation– angiogenesis– metastatic spread

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Targeting the EGFr for Anticancer Therapy

• Blocking the Activation of the EGFr Signaling Pathway In Tumor Cells:– inhibition of tumor cell growth– may lead to cancer cell death

• Targeting the EGFr Pathway With Molecules Such As Vectibix Offers Therapeutic Potential for Anticancer Therapy

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Vectibix (panitumumab)• Human IgG2 Kappa Monoclonal Antibody

– molecular weight = 147 kDa– binds specifically to human EGFr (Kd = 5 x 10-11 M)

• Indication*– as monotherapy for the treatment of EGFr-expressing, metastatic

colorectal carcinoma with disease progression on or following fluoropyrimidine-, oxaliplatin-, & irinotecan-containing chemotherapy regimen

• Administration/Dose– intravenous (60 – 90 minute infusion)– 6 mg/kg q2wks

• Pharmacokinetics (PK)– t½ = 7.5 days (mean)

* Indicated in patients with non-mutated (wild-type) KRAS in the EU

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Ligand LigandLigand

EGFr dimer

Mechanism of Vectibix

XX

Vectibix

- Vectibix targets the extracellular domain of the EGFr preventing:• the ligand from binding to the receptor• receptor dimerization • activation of the EGFr signaling pathway

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Vectibix Manufacturing Process History• Initial Manufacturing Process Used a Hybridoma Cell Line

• Material Generated From Hybridoma Manufacturing Process – initial preclinical studies (to support phase I)

• pharmacology• PK• toxicology

– phase I clinical study

• Prior to Phase III– manufacturing process changed using chinese hamster ovary

(CHO) cell line• higher productivity

(to support expected clinical & commercial demand)• improve process robustness

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Vectibix Manufacturing Process History Cont’d.

• Manufacturing Changes Included – hybridoma to CHO cell line– modifications to the manufacturing processes to support the cell line

change• cell culture process • media components• production bioreactor feeds

– manufacturing facility to support higher production yield

• What Did Not Change?– genetic sequence expressing Vectibix

• DNA sequence used to create CHO cell line generated from hybridoma cell line

– formulation– excipients

Same For Both Manufacturing Processes

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Comparability Assessment • Comprehensive Comparability Exercise Was Undertaken

– extent of the changes in the manufacturing process– timing of changes (prior to phase III)

• Objective of Comparability Assessment

– support using CHO material in chronic and reprotoxicity studies– to proceed into phase III clinical development with CHO material

• Comparability Assessment Included:– analytical tests– preclinical studies

• pharmacology• PK• toxicology

– clinical PK studyreview

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Comparability Assessment

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Comparability Analytical Studies• Analytical Studies Included Various Tests:

– binding assay– bioassay– UV scan– HPLC– others

• Results of Analytical Comparability Tests– minor differences between the 2 materials

• expected due to cell line change• well characterized and understood

– did not impact biological activity • in vitro potency between the 2 materials was comparable

(binding and bioassay)

• Analytical Data Supported Using CHO-Derived Material– pivotal toxicology studies – phase III clinical trial

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Comparability Pharmacology Studies

• In vivo studies conducted with hybridoma and CHO-derived material– mouse xenograft studies using A431 human epidermoid

carcinoma cells

• Results– both hybridoma and CHO material prevented and eradicated

established A431 tumor formation • similar doses • dose-dependent manner

– anti-tumor effects of hybridoma and CHO material were comparable

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Comparability Pharmacokinetic Study• Study Design

N = 24 male monkeys• single IV dose• 12 administered hybridoma material (7.5 mg/kg)• 12 administered CHO material (7.5 mg/kg)

CHO-Derived Vectibix

Hybridoma-Derived Vectibix

Parameter Mean SD N Mean SD N

AUC0-336h

(g·day/mL)619 83 12 664 143 12

Cmax

(g/mL)227 31 12 256 56 12

• The PK profiles of the hybridoma and CHO materials were comparable (based on AUC and Cmax)

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Monkey Comparability Pharmacokinetic StudyS

eru

m V

ect

ibix

Co

nc. (

g/m

L)

*Mean Vectibix concentration time profiles for the 2 materials are almost superimposable

Time (hrs)

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Overview of Toxicology Program • All Studies Conducted in Cynomolgus Monkeys

(pharmacologically relevant species)

• Initial Studies Used Hybridoma-Derived Material – tissue cross-reactivity– 4 and 13-week repeated dose

• Comparability Studies (hybridoma and CHO)– tissue cross-reactivity– 4-week repeated dose

• Pivotal Studies Used CHO-Derived Material– 6-month repeated dose– reproductive toxicity

Review

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Toxicology Comparability Studies

• Toxicology Comparability Studies – tissue cross-reactivity study

• compare tissue binding properties– 4-week monkey toxicity study

• compare toxicity profile• PK• antibody response

(monkey anti-human antibody response MAHA)

• Objective: Moving Forward with CHO Material – pivotal toxicology studies– phase III clinical study

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Tissue Cross-Reactivity Study

• Study Design– hybridoma- and CHO-derived Vectibix (biotinylated)– panel of human and cynomolgus monkey tissues

• Results– consistent with previous study using hybridoma material– binding observed primarily in epithelial cells within the

different tissues for both materials• skin, lung, breast, colon, eye• human and monkey tissues

• Tissue Binding Properties of Hybridoma- and CHO-Material Were Comparable

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4-Week Comparability Toxicity Study

• Administration: IV injection once weekly for 4 weeks

• 3 monkeys/sex/group terminated on day 28

• 1 monkey/sex/group terminated on day 57 (4-week recovery)

• Blood samples for TK and MAHA responses

Group Number

(material)

Dose Level

(mg/kg)

Number of Monkeys

(M/F)

1 0 (vehicle) 4/4

2(hybridoma)

7.5 4/4

3(hybridoma)

30 4/4

4(CHO)

7.5 4/4

5 (CHO)

30 4/4

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4-Week Comparability Toxicity Study – Results

• Primary Treatment-Related Toxicities – related to pharmacological activity of Vectibix – skin rash – diarrhea

• Toxicities in This Study Consistent with Previous Studies Using Hybridoma Material– also consistent with those observed in clinical trials (skin rash; diarrhea)– preclinical toxicity predictive of clinical toxicity

• No Remarkable Differences in Skin Rash or Diarrhea Between Hybridoma and CHO groups– severity– incidence

• Toxicity Profile Between Hybridoma and CHO Material Was Comparable

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CHO FemaleCHO Male

• PK Between Hybridoma and CHO Groups Comparable (exposure increased approximately dose proportionally)– consistent with previous studies using hybridoma material– consistent with monkey comparability PK study

7.5 mg/kg

Study Day

0 1 2 3 4 5 6 7

Se

rum

Pa

nitu

mu

ma

b C

on

c.

( g

/mL

)

0.1

1

10

100

1000

10000

30 mg/kg

Study Day

0 1 2 3 4 5 6 7

Se

rum

Pa

nitu

mu

ma

b C

on

c.

( g

/mL

)

0.1

1

10

100

1000

10000

2K CHO Female 2K CHO Male Hybridoma FemaleHybridoma Male

Se

rum

Ve

cti

bix

Co

nc

en

tra

tio

n (g

/mL

)

Se

rum

Ve

cti

bix

Co

nc

en

tra

tio

n (g

/mL

)

4-Week Comparability Toxicity Study - PK Results*

*Clearance of Vectibix increases with presence of MAHA after repeated administration, thus, pharmacokinetic comparisons were based on values after the first dose

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4-Week Comparability Toxicity Study – MAHA Responses

• The Number of MAHA Responses Between Hybridoma and CHO Groups Was Comparable

Group Number (material)

Dose Level (mg/kg)

Incidence of MAHA Responses (%)

1 0 (vehicle) 0

2(hybridoma)

7.5 6/8 (75%)

3(hybridoma)

30 4/8 (50%)

4(CHO)

7.5 5/8 (63%)

5 (CHO)

30 2/8 (25%)

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Clinical Comparability Pharmacokinetic Study

• Phase I study– open-label, multiple-dose, dose-rising trial in

patients with solid tumors– patients administered 6 mg/kg of Vectibix q2wk

• N = 7 patients administered hybridoma material• N = 10 patients administered CHO material

• Results – The PK parameters (AUC0-tau and Cmax) of hybridoma-

and CHO-derived material were comparable*

*90% confidence interval of the ratios between the CHO and hybridoma material for the PK parameters were within the 80% -125% interval

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Summary• Initial Manufacturing Process Used Hybridoma Cell Line

– phase I

• Manufacturing Process Changed – hybridoma to CHO cell line– manufacturing process– manufacturing facility

• Comprehensive Comparability Exercise Was Undertaken – extent of the changes– time changes occurred in clinical development program

• prior to phase III

• Comparability Exercise – analytical tests– preclinical studies– clinical pharmacokinetic study

comparable

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Summary Cont’d.• Toxicology Comparability – What We Learned in Hindsight

– tissue cross-reactivity study• binding properties of hybridoma- and CHO material were comparable

in human and monkey tissues

– monkey toxicity study• toxicology tightly linked to the pharmacology (skin rash/diarrhea)

– primary toxicities consistent with previous studies– no new or unexpected toxicities– toxicity profile well characterized and understood– preclinical toxicity predictive of clinical toxicity

• hybridoma and CHO groups

– toxicity profile– exposure– MAHA responses

comparable• chronic tox • phase III

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Summary Cont’d. Is a Comparability Toxicology Study Needed?

• What Do We Do Today?• Approach - Science-Based Comparability Decision Tree

• Questions Asked

• when did changes occur during clinical development program?– prior to pivotal clinical trials (phase III) or post-marketing?

• what are the extent of the manufacturing changes?– extensive vs. minor (e.g., cell line vs. excipient change)

• results of analytical tests?– comparable– differences detected

• what are the extent of the differences?– extensive or minor– are the differences well characterized and understood?

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• Approach - Science-Based Comparability Decision Tree

• Questions Asked – following unchanged?

– preclinical PK – pharmacodynamics in pharmacology studies– tissue binding properties (human and animal tissues)

– toxicology tightly linked to the pharmacology?– related to the pharmacological activity (“on target”)

– toxicity profile well characterized and understood?

– toxicity endpoints sensitive enough to detect meaningful differences?

– critical for study to provide reliable safety data

– preclinical toxicity predictive of clinical toxicity?

Summary Cont’d. Is a Comparability Toxicology Study Needed?

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Summary Cont’d. Is a Comparability Toxicology Study Needed?

• Applying a Science-Based Comparability Decision Tree Directs You In Determining

– would a toxicity study add relevant safety data to the comparability package?

– each program is case-by-case• approach for one molecule may not be the same as for

another molecule

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Summary Cont’d.• Would We Do a Toxicology Comparability Study

for Vectibix?– extensive changes in manufacturing process– occurred before phase III– analytical data showed minor differences

• in vitro potency comparable– preclinical data comparable

• pharmacology• PK • tissue binding properties

– toxicology closely linked to the pharmacology (skin rash/diarrhea)

– preclinical toxicity predictive of clinical toxicity

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• Applying a Science-Based Comparability Decision Tree Approach for Toxicology Studies:

• requires detailed insight to data collected during the preclinical and clinical development program

• data includes: – analytical– preclinical

» pharmacology» PK» toxicity

– clinical» pharmacology» PK» toxicity

Summary Cont’d.

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Acknowledgments• Jeanine Bussiere• Mary Ellen Cosenza• Ruth Lightfoot-Dunn• Andrew Fox• Ralph Klinke• Julie Lepin• Richard Lit• Peggy Lum• David Reese• Bing-Bing Yang• Many, many others• Most of all – the patients

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References• Vectibix, European Public Assessment Report, CHMP, 2007.

• Vectibix, FDA Review, Application Number 125147, approval 09/27/2006.

• Vectibix Prescribing Information, Thousand Oaks, CA: Amgen, Inc; 2008.

• Lacouture, M.E., and Lai, S.E. (2006). The PRIDE (papulopustules and/or paronychia, regulatory abnormalities of hair growth, itching, and dryness due to epidermal growth factor receptor inhibitors) syndrome. Br. J. Dermatol. 155: 841-865.

• Lenz, H.J. (2006). Anti-EGFr mechanism of action: anti-tumor effect and underlying cause of adverse events. Oncology. 20(5): 5-13.

• Miettinen PJ, Berger JE, Meneses J, et al. Epithelial immaturity and multiorgan failure in mice lacking epidermal growth factor receptor. Nature. 1995;376:337-341.

• O’keefe, P., Parrilli, M., and Lacouture, M.E. (2006). Toxicity of targeted therapy: focus on rash and other dermatologic side effects. Oncology Nurse Ed. 20(13): 1-6.

• www.Vectibix.com

• Yarden, Y., Silwkowski, MX. (2001). Untangling the ErbB signalling network. Nat Rev Mol Cell Biol. 2:127-137.

• Yano, S., Kondo, K., Yamaguchi, M., et al. (2003). Distribution and function of EGFr in human tissue and the effect of EGFr tyrosine kinase inhibition. Anticancer Res. 23: 3639-3650.