Evaluation of immunogenicity Case presentations CEMDC-PharmaTrain, Module 8. Budapest, Hungary, 12-May-2017 Vid Stanulovic MD, PhD Clinical pharmacologist, Clinical Development and Pharmacovigilance Consultant

Clinical immunogenicity testing Strategy for the evaluation of immungenicity is based on regulatory documentation: - FDA Guidance for Industry (2009): Assay development for Immunogenicity Testing of Therapeutic Proteins. Draft. - FDA Guidance for Industry (2014): Immunogenicity Assessment for Therapeutic Proteins Products. - EMA (2015) Guideline on Immunogenicity Assessment of Biotechnology-derived Therapeutic Proteins. EMEA/CHMP/BMWP/14327/2006 Rev. 1

Consequences Safety Impact Exposure/Efficacy Impact Cross reactivity with endogenous proteins Allergic reactions Immune complexes-complement activation Exposure/Efficacy Impact Neutralizing and/or clearing antibodies Enhanced drug clearance Drug accumulation

Risk-Based Testing Breadth of immunogenicity (testing) dependent on Likelihood of an immune response Likely clinical consequences of an immune response As the concern around immunogenicity increases, the level of testing should also increase Samples tested more frequently More thorough characterization

Clinical immunogenicity testing strategy 3-tiered approach Screening assay Tier 1: 5% false-positive  ADAs present? Reactive Negative Confirmatory assay Negative Tier 2: Are the detected ADAs specific for the drug? Confirmed Positive Titer Neutralizing Assay  Characterization Negative Tier 3: Do the specific ADAs possess neutralizing capacity? Confirmed Positive Titer Correlation ? with clinical observations

How to determine the screening cut point? SCP = level of response above which a sample is defined to be reactive (potential positive) and below which is probably negative Upper negative limit of 95% is recommended = risk-based approach (more appropriate to have 5% false-positive than false-negative)

How to determine the specificity cut point? Used to confirm the presence of ADA in sample found above the SCP Competitive inhibition by addition of the therapeutic protein in sample % inhibition calculated between sample measured unspiked and spiked with an excess of drug Sample is confirmed positive if its %inhibition is > Confirmation cut point (CCP) 0.1% of false-positive Measured signal > SCP => Reactive sample Addition (spike) of an excess of drug in sample Decrease of measured signal => Sample confirmed as positive if %inhibition > CCP Important: Suitability of the Cut-point needs to be re-assessed once baseline samples from patients become available

Clinical Immunogenicity reporting

Reporting of Clinical ImmunogenicityData Currently there is a lack of standardization in the terminology used for the collection, analysis, and presentation of immunogenicity results in clinical trial reports, regulatory documents (IND, IMPD) and product labels The aim of the initiative “Harmonization of the Reporting of Clinical Immunogenicity Data” is to foster a unified approach to assessing and describing immunogenicity (globally, but at least on company level) It is based on latest recommendations and “white papers”

Kinetics of the ADA response Reporting of Clinical Immunogenicity Data Sample Status / ADA Attributes / Subject Status * Kinetics of the ADA response ADA incidence *Evaluable subjects should also have a baseline sample. If baseline sample is missing, it should be treated as if negative.

Reporting of Clinical Immunogenicity Data Treatment Boosted ADA Treatment-boosted ADA: Pre-existing ADA that were boosted to a significant higher titer following drug administration than the baseline A difference in titer values between 2 samples representing at least two titer steps is considered significant. For example at least a 4-fold increase in titers for 2-fold or a 9-fold increase for a 3-fold serial dilution schema would be required 2-fold dilution scheme: 1:2 1:4 1:8 1:16 example: 3-fold dilution scheme: 1:3 1:9 1:27 1:81 9-fold increase 4-fold increase

Reporting of Clinical Immunogenicity Data ADA Incidence/Prevalence Subject status is used to calculate:

Reporting of Clinical Immunogenicity Data Kinetics of the ADA Response Focus on treatment-induced ADA A separate evaluation for the kinetics of treatment-boosted ADA might be performed in case a high number of pre-existing ADAs are detected Onset of ADA: Time period between the initial administration of the biologic drug and the first instance of treatment-induced ADA Report the “median time to ADA development” and the quartiles Q1 and Q3 Duration of ADA: Longevity of treatment-induced ADA Only calculated for subjects with at least two positive ADA samples Report the median duration of an induced ADA response and IQR

Reporting of Clinical Immunogenicity Data Kinetics of the ADA Response Important note: Categories listed below are independent from the dosing- and sampling regimen Transient ADA response Persistent ADA response Indeterminate ADA response

Kinetics of the ADA Response Transient Response Transient ADA response: Treatment-induced ADA detected only at one sampling time point during the treatment or follow-up observation period (excluding the last sampling time point) Treatment induced ADA detected at two or more sampling time points during the treatment (including follow-up period if any), where the first and last ADA-positive samples (irrespective of any negative samples in between) are separated by a period less than 16 weeks and the last time point is negative 4 8 12 24 48 36 week Half-life of endogenous IgGs: 21-25 days => a transient immune response (IgGs) is expected to be eliminated at the end of 5 x t1/2 (~16 weeks)

Kinetics of the ADA Response Persistent Response Persistent ADA response: Treatment induced ADA detected at two or more sampling time points during the treatment (including follow-up period if any), where the first and last ADA-positive on-treatment sample (irrespective of any negative samples in between) are separated by at least 16 weeks 4 8 12 24 36 48 week Half-life of endogenous IgGs: 21-25 days => a transient immune response (IgGs) is expected to be eliminated at the end of 5 x t1/2 (~16 weeks)

Kinetics of the ADA Response Indeterminate Response Indeterminate ADA response Only the last sampling time point is positive and all previous samples are negative The last two samples are positive but separated by a period less than 16 weeks 4 8 12 24 36 48 week

Case presentations

Case 1: Growth hormone Phase II trial Single patient with transient antibodies Characterization: Neutralizing Adverse events: No AEs suspected to be caused by the drug

Case 1: Growth hormone Originator (Genotropin®)

Efficacy response -- patient efficacy response (IGF-I) --efficacy response of the dose cohort (IGF-I) Confirmed NaB time-point

Case 1: Growth hormone For evaluation: History? HCV antibodies at screening tested positive but negative on retest Relevance? Clinical impact?

Case 2: Interferon beta Biosimilar interferon-beta for multiple sclerosis Hypersensitivity reported with a few weeks after initiating treatment The patient was interferon naive Investigator assessed the event as severe and definitely related Patient discontinued from the trial

Case 2: Interferon beta 1a Originator (Avonex®) 4.4 Special warnings and precautions for use 4.8 Undesirable effects

Case – Interferon beta No neutralizing antibodies detected – but consider the limitations of antibody assays Actions to be considered: History Follow-up Clinical Laboratory Rechallenge with the IMP?

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