Control Strategies for Small Molecule gComponents of Antibody-Drug Conjugates

Nathan C. Ihle, PhDExecutive Director, Process ChemistrySeattle Genetics IncSeattle Genetics, Inc

WCBP 2012Antibody-Drug Conjugates: Balancing Large and Small Molecule Control Strategies from Development to Commercialization23Jan2012San Francisco, CA

Seattle Genetics Company Overview

Biotechnology company focused on monoclonal antibody-based therapies for cancer

ADCETRIS™ (brentuximab vedotin) granted accelerated approvalADCETRIS (brentuximab vedotin) granted accelerated approval for 2 indications by the FDA in August 2011Leader in next-generation antibody-drug conjugate (ADC) technologyRobust ADC development pipelinep p p

Founded in 1998Located in Bothell, just north of SeattlePublicly traded (Nasdaq: SGEN) ~500 employeesLead ADC programsLead ADC programs

Brentuximab vedotin (SGN-35)SGN-75ASG-5ME

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ASG-22ME

ADCETRIS™ (Brentuximab Vedotin)

ADC directed to CD30

Granted accelerated FDA approval in ppAugust 2011 for two indications

Broad clinical development program to evaluate use in earlier lines ofto evaluate use in earlier lines of Hodgkin lymphoma and systemic ALCL and other CD30-positive malignancies

Corporate-sponsored trialsInvestigator-sponsored trials

Millennium MAA submission acceptedby EMA in June 2011

Seattle Genetics regulatory application to Canadian Health authorities planned for first half of 2012

Relapsed HL and systemic ALCL

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Antibody-Drug Conjugate (ADC)Mechanism of Action

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Brentuximab Vedotin Structure

DrugMMAE

cytotoxic agent

LinkerAntibodycAC10 anti-CD30

antibodyAttachment

groupProtease-

cleavage site cytotoxic agentantibody group cleavage site

cAC10: chimeric IgG1κ monoclonal antibodyLinker chemicall stable

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Linker: chemically stableMMAE: synthetic small molecule

Brentuximab Vedotin Manufacture

cAC10(I t di t )(Intermediate)

SGD 1006

Bulk Drug Substance Drug Product

SGD-1006(Intermediate)

cAC10 and SGD-1006 classified as cGMP intermediatesEach with dedicated 3 2 S section

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Each with dedicated 3.2.S section

Quality Definitions

Control Strategy:A planned set of controls, derived from current product and process understanding that assures process performance and product quality. The u de s a d g a assu es p ocess pe o a ce a d p oduc qua y econtrols can include parameters and attributes related to drug substance and drug product materials and components, facility and equipment operating conditions, in-process controls, finished product specifications, and the associated methods and frequency of monitoring and control.(ICH Q10)( Q )

Begins with an assessment of quality attributes to identify Critical Quality Attributes (CQAs)

Critical Quality Attribute:A physical, chemical, biological or microbiological property or characteristic that should be within an appropriate limit range or distribution to ensure the desiredshould be within an appropriate limit, range, or distribution to ensure the desired product quality.(ICH Q8(R2))

Emphasis on attributes that impact safety and/or efficacy

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Emphasis on attributes that impact safety and/or efficacy

Quality Attributes for an ADC

Universal quality attributesPotencyPurityMicrobiological attributes

Attributes typically associated with antibody productsCharge variantsAggregatesHost cell protein

Attributes typically associated with small moleculesChiral purityResidual solvents

Attributes unique to ADCsDrug-to-antibody molar ratio (MRD)Free drug-related impurities

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Quality Attributes for an ADC

Universal quality attributesPotencyPurityMicrobiological attributes

Attributes typically associated with antibody productsCharge variantsAggregatesHost cell protein

Attributes typically associated with small moleculesChiral purityResidual solvents

Attributes unique to ADCsDrug-to-antibody molar ratio (MRD)Free drug-related impurities

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Quality Attribute: Stereochemical Purity of Conjugated Small Molecule

ADC attributes where effect might be observedCytotoxicityDrug directed Western blotDrug-directed Western blotCDAAAPeptide map

Relying on control by testing ADC is not optimumMany tests are influenced by multiple attributesSt h i t i t bli h d l iStereochemistry is established early in processProcess understanding teaches us that once established, stereochemistry does not changeConjugation makes differences harder to detect

Li i i f l i l h d○ Limitation of analytical methods

Control stereochemical purity early, during manufacture of the small molecule

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molecule

Quality Attribute: Stereochemical Purity of Conjugated Small Molecule

13 St t13 Stereocenters213 stereoisomers possible8192 diastereomers (1 or more stereocenters inverted)

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Quality Attribute: Stereochemical Purity of SGD-1006

12 Stereocenters212 stereoisomers possible1 enantiomer (mirror image, all stereocenters inverted)4095 diastereomers (1 or more stereocenters inverted)

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Manufacture of SGD-1006

Produced by chemical manufacturing processConvergent chemical processConvergent chemical processDefined regulatory starting materialsAssembled in multiple stagesIsolated intermediates

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SGD-1006 manufactured and released as GMP intermediate

Quality Attribute: Enantiomeric Purity of Conjugated Small Molecule

Proper enantiomer required for cytotoxicity Therefore, a CQA for SGD-1006

- vs -

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Enantiomeric Control of (1S,2R)-(+)-Norephedrine

- vs -

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Enantiomeric Control of (1S,2R)-(+)-Norephedrine

- vs -

Specification includesChiral HPLC methodLimit on (1R,2S)-(-)-norephedrine

Similar approach applied to all starting materialsStarting material controls provide the control of the CQAs enantiomeric purity of SGD 1006 and enantiomeric purity of

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enantiomeric purity of SGD-1006, and enantiomeric purity of conjugated small molecule

Quality Attribute: Stereochemical Purity of Conjugated Small Molecule

Diastereomeric Purity – a CQAMost isomers will have diminished cytotoxicity – impact is potency

Controls to considerStarting materials○ Wrong enantiomer or diastereomer of starting material will result in production of

diastereomers which may carry forward to SGD-1006 and ADCProcess controls○ Some stereocenters may be sensitive to some reaction conditions

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Quality Attribute: Diastereomeric Purity of Conjugated Small Molecule

Proper diastereomer required for cytotoxicity Therefore, a CQA for SGD-1006

- vs -

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Diastereomeric Control of (1S,2R)-(+)-Norephedrine

HO HO

H2N

HO

H2N

HO

(1S,2R)-(+)- (1R,2R)-(-)-

- vs -

Norephedrine Norpseudoephedrine

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Diastereomeric Control of (1S,2R)-(+)-Norephedrine

HO HO

H2N

HO

H2N

HO

(1S,2R)-(+)- (1R,2R)-(-)-

- vs -

Norephedrine Norpseudoephedrine

Specification includes2nd HPLC methodLimit on (1R,2R)-(-)-norpseudoephedrine

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Quality Attribute: Diastereomeric Purity of Conjugated Small Molecule

Are additional controls for benzylic alcohol stereochemistry required?

I t h i t t bl ?Is stereochemistry stable?If unstable, what process parameters are important to control to control this attribute?Does process clear diastereomers?Are analytical methods capable of measuring diastereomers?

Process understanding is keyOrigin and fate of impurities

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Quality Attribute: Diastereomeric Purity of Conjugated Small Molecule

Additional controls for benzylic alcohol stereochemistryProcess design

I l d t d i d t d i bl i○ Include steps designed to remove undesirable isomersProcess understanding○ Investigate and understand origin of isomer during manufacture and demonstrated

ability of steps to clear itProcess parameter controls○ Exposure of in-process materials to acidic conditions scrambles stereochemistry○ Implement process parameter controls to assure operation within acceptable operating

range (AOR)Non-critical process parameter, because normal operating range (NOR) much narrower than proven AOR

Intermediate specifications○ Test methods and established limits for this isomer in isolated intermediatesR l ifi tiRelease specification○ Test method, and limits for this isomer in the release of SGD-1006

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Quality Attribute: Diastereomeric Purity of Conjugated Small Molecule

SGD-1006

DiastereomerDiastereomer

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Suitable control demonstrated via process validation

Other Quality Attributes of SGD-1006

Critical Quality AttributesImpact a CQA of the drug product

Non-Critical Quality AttributesIndicator of process performance, but do not impact a CQA of the drug productE.g. – residual solvents

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Quality Attribute: Residual Solvents in SGD-1006

Residual Solvents – a Non-Critical Quality AttributeSolvent residues from SGD-1006 manufacturing processManufacturing experience demonstrates levels below ICH limits so no toxicityManufacturing experience demonstrates levels below ICH limits, so no toxicity concernsAdditional processing provides further clearanceTherefore a Non-Critical Quality Attribute

However, residual solvents is an indicator of process performance, therefore important to monitor and control

ControlsProcess designProcess understandingProcess parametersProcess parametersIn-process testingRelease testing

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Suitable control demonstrated via process validation

Conclusions

Control strategy for ADCs relies on assessment of quality attributes of the final drug product, and process understanding

Each quality attribute assessed for possible control

Many controls impact multiple quality attributes

C t l t t f tt ib t i t d ith th j t d llControl strategy for attributes associated with the conjugated small molecule relies mostly on controls applied prior to conjugation

Many small molecule quality attributes and associated controls are non-critical

Control of regulatory starting materials is one of the most important aspects of the control strategy

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Acknowledgements

Seattle Genetics StaffProcess Sciences DepartmentTechnical Operations Department

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