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Immunogenicity as a key issue for biotechnology-

derived products.

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Carlo Pini (carlo.pini@iss.it)

DirectorNational Center for Immunobiologicals Research and Evaluation - CRIVIB

Istituto Superiore di SanitàRoma

Italian Delegate - Biologics Working Party (CHMP/BWP) EMA - London

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Disclaimer

• The content of the following presentation represents the speaker’s view and does not reflect any official point of view.

• According to the EMA policy (0044 MA/513078/2010)– No direct conflict of interest– One indirect conflict of interest

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Biologicals/biotechnologicals products

• Biologicals/biotechnologicals products are complex macromolecules which cannot be fully characterised from the analytical point of view but whose quality attribute are also largely defined by the manufacturing process.

• They may be:– copies of naturally occurring molecules normally

present in the human body such as interferons, growth factors (G-CSF, erithropoietin ) antibodies, etc.

– “foreign molecules” which have been designed to interfere with a certain pathogenic mechanism.

– Molecules which have been intentionally designed to be immunogenic (recombinant vaccines). Immunogenicity is therefore a positive characteristic of the product.

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Immunogenicity• With the exception of vaccines, immunogenicity is a

negative unwanted property of a given molecule, and a number of attempts have been made to design a recombinant molecule to reduce/abolish this characteristic.

• The predictive value of non-clinical studies for evaluation of immunogenicity of a biological medicinal product in humans is low due to inevitable immunogenicity of human proteins in animals.

• Differences between neutralising vs non-neutralising antibodies.

• In the clinical setting, careful planning of immunogenicity evaluation should include data systematically collected from a sufficient number of patients.

• Immunogenicity issues should be further addressed in the Risk Management Plan.

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Immunogenicity

• The consequences of an immune reaction to a therapeutic protein range from transient appearance of antibodies without any clinical significance to severe life-threatening condition.

• The immunogenicity of therapeutic proteins. can be considered to be patient-, disease- or product-related

• data on possible unwanted immune reactions to therapeutic proteins are required before marketing authorisation, problems may still be encountered in the post-authorisation period.

• Depending on the immunogenic potential of the therapeutic protein and the rarity of the disease, the extent of immunogenicity data before approval might be limited

• Further systematic immunogenicity testing might become necessary after marketing authorization, and may be included in the risk management plan.

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Immunogenicity

• A lot of experience has been gained since the very first recombinant product (murine monoclonal antibody – Muromomab CD3 – middle 1980s) was authorized.

• As a consequence, several technical approaches have been introduced to manufacture less and less immunogenic products

• For example, murine MoAb from ascites have been replaced by fully humanized MoAbs where the only “foreign” structure is represented by a few aas defining the binding region.

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Immunogenicity

• The progress of the scientific knowledge in the field has suggested in the recent past that the immunogenicity issue should be largely treated in a CHMP Guideline (CHMP/BMWP/14327/06).

• The Guideline came into effect in April 2008• A number of important aspects have been covered in the document• The scope of the Guideline is not restricted to recombiant products

but it applies to biologicals in general, when feasible.• Very important point, this guideline should be considered together

with the relevant guidelines on Biosimilar products and on Comparability (quality, non clinical and clinical parts).– Impact of changes in the manufacturing process on immunogeniciy– Immunogenicity of the biosimilar product

• Therefore evaluation of immunogenicity should be a multidisciplinary task, encompassing joint efforts of quality, non-clinical and clinical experts.

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Immunogenicity (CHMP/BMWP/14327/06)

• Guideline on immunogenicity assessment of Therapeutic proteins– Immunogenicity guideline: general section

• Basic concepts, immunogenicity and humanisation, molecular size, percentage of murine parts, etc.

• Patients and disease related risk factor. • In the comparability exercise (post changes products and biosimilars, the

immunogenicity in non clinical model may provide useful information. The antibody you get may be irrelevant or may neutralise the whole activity of the drug. Distinction between neutralising and non-neutralising antibodies. PK influencing antibodies not easily determined and distinguished from the neutralising antibody.

• Difference between infusion reaction and anafilactic reaction which should prevent the patient to get treated.

• Risk management and standardised measurements methods. – Immunogenicity guideline: Annex I

• Unwanted immunogenicity and various types of antibodies and different antibodies require different methods.

• It is impossible to predict a number of factors with antibodies and studies are required.

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General section

• Factors that may influence the development of an immune response against a therapeutic protein– Patient- and disease-related factors

• Genetic factors modulating the immune response• Disease-related factors and age• Concomitant treatment• Duration, route of administration, treatment modalities• Previous exposure to similar or related proteins

– Product related risk factors of immunogenicity• Protein structure• Formulation• Aggregates and impurities

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General section • Non-clinical assessment of immunogenicity and its

consequences– Therapeutic proteins show species differences in most cases. Thus,

human proteins will be recognised as foreign proteins by animals.– Measurement of antibodies in non-clinical studies are however

requested as part of repeated dose toxicity studies (see ICH S6)– the comparison of the antibody response to the reference product in

an animal model may be part of the comparability exercise both for similar biological medicinal products and for changes in manufacturing processes

– An immune response to a therapeutic protein representing a counterpart to an endogenous protein may result in cross-reactivity, directed to the endogenous protein in cases where endogenous protein is still produced.

– Both humoral and cellular immune responses (where relevant) should be considered.

– Animal homologous models useful

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General section • Assays for detecting and measuring immune

responses in humans.– Assay strategy– Antibody assay

• Screening

• Confirmation

• Specificity

• Neutralisation assay

• Assay validation, standardisation and controls

• Characterisation and strategy

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Consequences of immunogenicity • Efficacy

– Factors inducing clinical consequences can be the epitope recognised, affinity, class of the antibody, the amount of antibodies generated, etc.

– Capability of being cytotoxic (cell mediated, complement mediated)

– Antibodies recognising epitopes on the therapeutic protein not linked to activity are expected to be associated with less clinical consequences.

– “Neutralising” antibodies, interfering with biological activity by binding to or near the active site, or by induction of conformational changes, can induce loss of efficacy.

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Consequences of immunogenicity

• Safety– patients who develop antibodies are more likely to

show infusion-related reaction– the consequence of immunogenicity is product-

specific and can elicit unexpected clinical symptoms.

– Immediate hypersensitivity– Delayed hypersesitivity and immune complexes– Cross-reactivity with an endogenous counterpart

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Consequences of immunogenicity

• Immunogenicity and Clinical Development– Immunogenicity assessment should be part of the

clinical trials, since the correlation to clinical efficacy and safety is important

– Several factors such as dose, schedule and treatment modalities influence the development of an immune response against a therapeutic protein

– For products intended for chronic use, it may be necessary to study the evolution and persistence of an observed immune response

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Consequences of immunogenicity

• Consequences on pharmacokinetics of the product– Influence of non-neutralising antibodies – Methodology aspects to assess comparability of

immunogenicity potential as part of a comparability exercise

– Applicants should make an effort to select a homogeneous and clinically relevant patient population that allows for such comparisons.

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Risk Management Plan (RMP)• The applicant should present a risk management plan in

accordance with current EU legislation and CHMP Guideline on Risk Management Systems for Medicinal Products for Human Use (EMEA/CHMP/96268/2005).

• The extent of data on immunogenicity that can be obtained during the clinical development programme of a biotechnology-derived product before approval depends on the event rate, driven both by the immunogenic potential of the protein and the rarity of the disease.

• Therefore, further systematic immunogenicity testing might become necessary after marketing authorization, and may be included in the Risk Management Plan.

• For planning immunogenicity assessment in the post marketing setting, the same recommendations apply as discussed in previous sections of this guideline.

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Annex 1

• Further details on methods for assessment and characterisation of immunogenicity– Types of antibody assays

• Screening assays

• Assays for confirming antibody positivity

• Assays for dissecting the specificity

• Neutralization assays

• Assays for assessing cell-mediated immune responses

• Assay characteristics

• Standardisation, reference materials, well characterized controls and assay validation, interpretation of Results

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Immunogenicity of biologicals

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Product-specific guideline

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Immunogenicity of MoAbs

• This guideline addresses issues relating to the unwanted immunogenicity of monoclonal antibodies (mAbs) intended for clinical use.

• These include factors impacting on:– immunogenicity of mAbs, – clinical consequences of immunogenicity– assay related problems, assessing neutralizing

antibodies induced by mAbs – consideration of a risk-based approach for the

evaluation of immunogenicity of mAbs.

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Specific Issues

• While many aspects of immunogenicity of mAbs are not different from those for other therapeutic proteins, there are several aspects that require more specific considerations.

• some specific aspects of immunogenicity are exclusively or primarily relevant for mAbs or novel mAb derivatives (e.g. Fab fragments, scFv, nanobodies, minibodies)

• This guideline considers the major quality and clinical aspects that are important for adequately addressing the immunogenicity of MoAbs

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Antibodies anti-MoAbs• Detection of antibodies against mAbs is often

more problematic, difficult and can be technically challenging.– Presence of mAb product in samples for analysis

– Confirmatory Assays

– Controls

• Assessing the neutralising capacity of antibodies induced against mAbs– Mechanism of action of the MoAb (Complement, cells)

• Immunogenicity risk management of mAbs

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Risk identification • Prior knowledge

• Mab structure– the immune response is predominantly anti-

idiotypic (as the complementarity determining regions - CDR - are hypervariable in sequence

– Hidden epitopes and new epitopes in conjugated MoAbs

– Impurities and other quality attributes

• Mechanism of action

• Clinical factors (age, previous exposure, etc.)

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Conclusions• Immunogenicity of biologicals is a well know

phenomenon• However mechanisms involved are very complex and

deserve specific investigations and scientific approaches

• The nature of the induced immune response needs to be clarified and it impact on safety and efficacy should be understood (neutralising vs non-neutralising antibodies)

• Trials available at the time of the MAA may not be large enough to identify less frequent patients capable of mounting an immune response against the product.

• Risk management Plan must take into account all potential issues linked with immunogenicity.