Summary Basis of Decision for Enzeevu

Enzeevu was developed as a biosimilar of the reference biologic drug, Eylea. The weight of evidence of similarity between a biosimilar and the reference biologic drug is provided by structural and functional studies. Biosimilars are manufactured to the same regulatory standards as other biologic drugs. In addition to a typical chemistry and manufacturing data package that is submitted for a standard new biologic drug, biosimilar submissions include extensive data demonstrating similarity to the reference biologic drug.

Comparative Structural and Functional Studies

The biosimilarity evaluation was conducted as a three-way pairwise analytical assessment of Enzeevu, Eylea sourced from the European Union (herein referred to as Eylea EU), and Eylea sourced from the United States (herein referred to as Eylea US). Eylea EU and Eylea US were demonstrated to be comparable, and both of them were deemed suitable proxies for Eylea authorized in Canada as they met all of the requirements for a non-Canadian reference biologic drug outlined in the Information and Submission Requirements for Biosimilar Biologic Drugs Guidance Document.

The strength, dosage forms, and routes of administration for Enzeevu are the same as those for Eylea EU, Eylea US, and Eylea authorized in Canada. However, the Enzeevu drug product is formulated in L-histidine/L-histidine monohydrochloride monohydrate, polysorbate 20, and trehalose dihydrate, at pH 5.7, while the Eylea drug product is formulated in a phosphate buffer containing sucrose, sodium chloride, and polysorbate 20, at pH 6.2.

The biosimilarity assessment included a comprehensive comparability exercise including biological and physicochemical characterization, as well as forced degradation studies. Enzeevu was demonstrated to be highly similar to Eylea with respect to protein content, sequence, higher-order structure, glycans, charge and size variants, post-translational modifications, potency, target binding, thermal stability, and impurity and degradation profiles. Minor differences observed in some impurity levels, post-translational modifications, and in glycosylation profiles are not expected to impact clinical efficacy, pharmacokinetics or safety, and do not preclude a determination of biosimilarity.

Overall, the results of the biosimilarity assessment support the quality requirements for Enzeevu to be considered a biosimilar of Eylea.

Characterization of the Drug Substance

Aflibercept is a recombinant fusion protein composed of portions of human vascular endothelial growth factor (VEGF) receptors 1 and 2 extracellular domains fused to the fragment crystallizable (Fc) portion of human immunoglobulin G1 (IgG1).

Detailed characterization studies were performed to provide assurance that aflibercept consistently exhibits the desired characteristic structure and biological activity.

Results from process validation studies indicate that the processing steps adequately control the levels of product- and process-related impurities. The impurities that were reported and characterized were found to be within established and acceptable limits. A risk assessment for the potential presence of nitrosamine impurities was conducted according to requirements outlined in Health Canada’s Guidance on Nitrosamine Impurities in Medications. The risk of the formation or introduction of nitrosamines during the drug substance and drug product manufacturing processes is considered negligible or low; therefore, no confirmatory testing is required.

Manufacturing Process of the Drug Substance and Drug Product and Process Controls

The drug substance is manufactured using a Chinese hamster ovary cell line genetically engineered to express the protein. After thawing of one vial of the working cell bank, the cell culture is serially expanded to allow for the inoculation of a production bioreactor. The protein in the harvested cell culture fluid is purified through a series of chromatography, virus inactivation, and virus filtration steps. This is followed by an ultrafiltration/diafiltration step, filtration, and storage of the drug substance at or below -60 °C.

The drug product manufacturing process involves thawing of the drug substance, preparation of excipients solution, compounding, bioburden reduction and sterile filtration, aseptic filling, stoppering, and visual inspection. Enzeevu is supplied as a sterile 40 mg/mL solution in a 2 mL glass vial or a 0.5 mL prefilled syringe. None of the non-medicinal ingredients (excipients) in Enzeevu are prohibited for use in drug products by the Food and Drug Regulations. The compatibility of aflibercept with the excipients is supported by the stability data provided.

The drug substance and drug product manufacturing processes are controlled by multiple process parameters, in-process controls, and batch release and stability testing with defined operating ranges, action limits, and acceptance criteria that have been established based on a risk assessment and process characterization studies. The process controls in place are considered appropriate to ensure the drug substance and drug product manufactured meet the predefined specifications.

Process validation was conducted with several drug substance and drug product batches manufactured consecutively at the intended commercial scale. All process parameters and in-process controls met their respective predefined operating ranges and acceptance criteria or action limits. Batch release data were consistent between process validation batches and were within the release specification limits. Data from ancillary validation studies (in-process hold times, impurity clearance, resin and membrane lifetimes, filters, extractables and leachables testing, sterility assurance, filling, shipping, and other supporting activities and equipment) also support the consistent manufacture of Enzeevu drug substance and drug products. Together, the process validation data demonstrate that the commercial-scale manufacturing processes are capable of consistently producing drug substance and drug product batches that meet the predefined specifications. Continued process verification protocols are in place to ensure that the commercial manufacturing process remains in a state of control.

Control of the Drug Substance and Drug Product

The proposed release and stability specifications for the drug substance and drug product were appropriately established and justified. Upon Health Canada’s request, several specification limits were tightened to more accurately reflect the manufacturing process capability and historical data. As a result, they have been aligned with the limits set by the European Medicines Agency. All release and stability acceptance criteria were met for the drug substance and drug product.

Compendial and non-compendial analytical methods used were demonstrated to be suitable for their intended purpose by verification and/or validation studies, and were successfully transferred to the proposed testing sites.

The reference standards are well characterized and an appropriate program is in place to qualify new primary and working reference material.

Enzeevu is a Schedule D (biologic) drug and is, therefore, subject to Health Canada's Lot Release Program as per the Guidance for Sponsors: Lot Release Program for Schedule D (Biologic) Drugs.

Stability of the Drug Substance and Drug Product

Based on the stability data submitted, the proposed shelf life and storage conditions for the drug substance and drug product were adequately supported and are considered to be satisfactory. The shelf life is 36 months for the vial presentation and 24 months for the prefilled syringe presentation, when they are stored at 2 °C to 8 °C.

The compatibility of the drug product with the container closure system was demonstrated through stability studies and studies of extractables and leachables.

Facilities and Equipment

Based on the information reviewed, on-site evaluations of the drug substance and drug product manufacturing sites were not deemed necessary.

The design, operations, and controls of all facilities and equipment involved in the production are considered suitable. The sites are compliant with good manufacturing practices.

Adventitious Agents Safety Evaluation

The manufacturing process of the drug substance incorporates adequate control measures to prevent contamination and maintain microbial control.

Master cell banks, working cell banks, end-of-production cell banks, and unprocessed bulk undergo thorough testing for detectable adventitious agents (bacteria, fungi, mycoplasma, and viruses). The cell culture process includes in-process tests to monitor for bioburden, endotoxins, mycoplasma, and viruses. Scaled-down viral clearance studies demonstrate that the downstream purification process is capable of inactivating or removing model viruses with a diverse range of viral properties.

No raw materials of animal or human origin were used during cell bank preparation, or during drug substance and drug product manufacturing.

The drug product formulation does not contain excipients of animal or human origin.

For biosimilars, the degree of similarity to the reference biologic drug at the quality level determines the scope and the breadth of the required non-clinical data. Non-clinical studies serve to complement the structural and functional studies and address potential areas of residual uncertainty.

According to the Guidance Document: Information and Submission Requirements for Biosimilar Biologic Drugs, where similarity is well established by structural and functional studies, and where extensive in vitro mechanistic studies are indicative of similarity, non-clinical in vivo studies may not be necessary.

Nevertheless, in order to satisfy requirements from other drug regulators, the sponsor conducted one 15-day, non-Good Laboratory Practice pharmacokinetic study in New Zealand White rabbits to compare the vitreous humour distribution and systemic pharmacokinetics of Enzeevu and Eylea sourced from the European Union (herein referred to as Eylea EU). Eighteen animals per treatment group received a single intravitreal injection of Enzeevu or Eylea EU at a dose of 1.2 mg per eye in both eyes. The study showed that Enzeevu and Eylea EU exhibited similar pharmacokinetic profiles in vitreous humour. In addition, the distribution of aflibercept in serum was also found to be comparable for Enzeevu and Eylea EU.

Overall, the non-clinical data are supportive of similarity between Enzeevu and Eylea EU.

The purpose of the clinical program for a biosimilar is to demonstrate that there are no clinically meaningful differences between the biosimilar and the reference biologic drug. The structural complexity of the biologic drug and availability of a relevant and sensitive pharmacodynamic endpoint determine the scope and the breadth of the required clinical data. The clinical program is designed to complement the structural and functional studies and address potential areas of residual uncertainty.

Comparative Pharmacokinetics

Due to the minimal systemic exposure of aflibercept expected after intravitreal injection and the invasiveness of intravitreal injections, a Phase I comparative pharmacokinetic study in healthy volunteers was not conducted.

The pharmacokinetic profiles of Enzeevu and Eylea were compared in a subset of patients with neovascular (wet) age-related macular degeneration from a Phase III study (CSOK583A12301, described in the Comparative Efficacy, Safety, and Immunogenicity section). For the purpose of this drug submission, Health Canada considered Eylea sourced from the European Union (herein referred to as Eylea EU) a suitable proxy for Eylea authorized in Canada, as it met all of the requirements for a non-Canadian reference biologic drug stipulated in the Information and Submission Requirements for Biosimilar Biologic Drugs Guidance Document.

The pharmacokinetic analysis set of Study CSOK583A12301 included 43 patients: 23 in the Enzeevu group and 20 in the Eylea EU group. Concentrations of total and free aflibercept were determined before the first injection on Day 1 and 24 hours after the first injection (Day 2) and then on Day 58, approximately 24 hours after the third injection. Given the limited number of patients, the analysis of the obtained pharmacokinetic data was descriptive. In both groups, the measured concentrations of total and free aflibercept were generally low and highly variable. The results confirmed the expectation of low systemic exposures of aflibercept following intravitreal injections, and showed that the systemic exposure of aflibercept was similar between the treatment groups.

Overall, the limited clinical pharmacology data support the pharmacokinetic similarity of Enzeevu and Eylea.

Comparative Efficacy, Safety, and Immunogenicity

The efficacy, safety, and immunogenicity of Enzeevu and Eylea EU, administered intravitreally in adult patients with neovascular (wet) age-related macular degeneration were compared in a Phase III, multicentre, randomized, double-masked, two-arm parallel study, CSOK583A12301.

In total, 485 subjects were randomized in a ratio of 1:1, 484 of whom received a 2 mg/0.05 mL dose of Enzeevu or Eylea EU by intravitreal injection. Patients received treatment once every 4 weeks for the first 3 months, followed by treatment once every 8 weeks until the last dose was administered at Week 48.

The primary efficacy endpoint was the mean change from baseline in best-corrected visual acuity (BCVA) at Week 8. In the per-protocol set, the difference in least-squares means of the change from baseline in BCVA at Week 8 between Enzeevu and Eylea EU was -0.3 letters with a 95% confidence interval (CI) of -1.8 to 1.3 letters and a 90% CI of -1.5 to 1.0 letters. The 95% CI and the 90% CI were entirely contained within the prespecified equivalence margin of -3.5 to 3.5 letters and -3.0 to 3.0 letters, respectively, supporting a demonstration of comparative efficacy.

The safety profile of Enzeevu observed in Study CSOK583A12301 is consistent with the known safety profile of Eylea. The overall incidence of adverse events was consistent between Enzeevu and Eylea EU throughout the study. No clinically meaningful imbalances were observed in the severity of adverse events and the rates of serious adverse events, adverse events of special interest, or discontinuations due to adverse events. In total, six patients died during the study: five patients (2.0%) in the Enzeevu group and one patient (0.4%) in the Eylea EU group. The deaths were considered not related to study treatment or study procedure and were attributed to the subjects’ medical conditions.

Treatment with any therapeutic protein is accompanied by the risk of immunogenicity (the development of anti-drug antibodies [ADAs], which have the potential to neutralize the biological activity of the drug). The incidence of ADAs was low in both treatment groups throughout the study, which precluded assessing the impact of the ADAs on the efficacy and safety of the drugs.

Overall, the submitted results of the comparative Phase III study indicate that there are no clinically meaningful differences between Enzeevu and the reference biologic drug in terms of efficacy, safety, and immunogenicity.

Appropriate warnings and precautions are in place in the approved Product Monograph for Enzeevu to address the identified safety concerns, as is found in the Product Monograph for Eylea. The Adverse Reactions section of the Product Monograph for Enzeevu is based on the clinical experience with Eylea.

Indications

The sponsor sought the authorization of Enzeevu for the indications of Eylea that had been authorized for adults at the time the New Drug Submission for Enzeevu was filed.

Similarity between Enzeevu and Eylea was established in accordance with the Guidance Document: Information and Submission Requirements for Biosimilar Biologic Drugs. The demonstration of similarity between a proposed biosimilar and its reference biologic drug enables the sponsor’s submission for the proposed biosimilar to rely on the safety and efficacy information already generated for the reference biologic drug, and therefore clinical trials are not required to support each of the sought indications. The sponsor provided data from a comparative clinical trial conducted in adult patients with neovascular (wet) age-related macular degeneration. In addition, the sponsor provided an acceptable scientific rationale for requesting the authorization of indications that were not directly studied in the clinical development program for Enzeevu. The rationale addressed the consistent mechanism of action of aflibercept across all approved indications and the comparable pharmacokinetic, safety, and immunogenicity profiles of aflibercept across different approved indications and patient populations.

Upon review of the evidence submitted, Enzeevu was authorized for the treatment of the following conditions:

• neovascular (wet) age-related macular degeneration

• visual impairment due to macular edema secondary to central retinal vein occlusion

• visual impairment due to macular edema secondary to branch retinal vein occlusion

• diabetic macular edema

• myopic choroidal neovascularization