The study results are presented in accordance with the CONSORT statement.
This randomized, prospective, investigator-blinded, multiple-dose, multicenter, comparative, parallel-group study was conducted at rheumatology departments of 15 multi-specialty hospitals/ centers across India from May 2016 to Apr 2017. Patients received 40 mg subcutaneous injection of test or reference product in 2:1 ratio along with MTX (10–25 mg/week) every other week over a period of 24 weeks. Patients who were on stable doses of salicylates, nonsteroidal anti-inflammatory drugs and low doses of corticosteroids (up to 10 mg of prednisolone or equivalent) continued the same dosage till the study completion.
Randomization scheme was generated by permuted block randomization technique by using SAS® (version 9.3 or higher) system software (SAS Institute Inc., USA). Treatment allocation was done centrally after verification of patient eligibility at study sites as per randomization schedule for the study center. This study was an investigator-blinded study to eliminate the assessment bias. Investigators i.e. practicing consulting rheumatologists at the clinical trial sites responsible for the conduct of the clinical trial or designee who assessed study endpoints was blinded to the study medication allocation. Each site has an independent pharmacist who was communicated treatment allocation details and other site team was kept blinded. Independent pharmacist in turn retrieved allocated kit and administered study drug during each visit.
This study was conducted in compliance with the ICH Tripartite guideline regarding Good Clinical Practice and Declaration of Helsinki (Brazil, October 2013) , and Schedule Y (amended Drug & Cosmetic Act 2013) , and Guidelines for Similar Biologics 2016, India  along with subsequent amendments and Indian regulatory laws governing biomedical research in human patients. The study was registered at Clinical Trial Registry-India (CTRI) prior to initiation (CTRI/2016/04/006884) of patient screening. Study was reviewed and approved by institutional ethics committees before its commencement at various sites in India. Written informed consent was obtained from patients before study initiation.
Patients of either gender aged ≥18 years to ≤65 years with active RA, concomitantly receiving MTX (10–25 mg/week) for no less than 3 months and on a stable dose between 10 and 25 mg/week for at least 4 weeks were included in this study. Active RA was defined as per the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria with RA score of ≥6 and disease duration of at least ≥3 months before baseline. Patients with swollen joints ≥6 (66-joint count), tender/painful joints ≥6 (68-joint count), C-reactive protein (CRP) level of > 6 mg/L and erythrocyte sedimentation rate (ESR) > 28 mm/h  were included in the study. Patients with functional class IV as per ACR classification of functional status, receiving DMARDs within 4 weeks before randomization and use of any anti-CD4 therapy, TNF-alpha antagonists, interleukin (IL-1) antagonists, intra-articular/parenteral corticosteroids within 4 weeks prior screening, history of systemic or other chronic infections, systemic manifestations of RA, or those who have used live or attenuated vaccines within 8 weeks before screening were excluded.
Efficacy and safety assessments
The primary endpoint was to compare the proportion of patients achieving ACR20 criteria at week 12 in between treatment groups. All the patients were evaluated by using ACR response criteria. Patients achieving 20, 50 and 70% improvement in major ACR criteria from baseline to week 12 were considered as ACR20, ACR50 and ACR70 responders. Patients who did not achieve ACR20 at week 12 were classified as treatment failures and withdrawn from the study. Remaining patients continued the treatment up to week 24. Secondary endpoints were proportion of patients achieved ACR20 at week 24, and ACR50 and ACR70 at weeks 12 and 24 in both treatment arms. Patients were assessed for Disease Activity Score 28 joint count–C-reactive protein (DAS28-CRP) and Health Assessment Questionnaire–Disability Index (HAQ-DI) during the study. HAQ (health assessment questionnaire) was administered at baseline, every other week till 8 weeks, 12 weeks (primary analysis), 16 weeks, 20 weeks and at 24 weeks. It included 25 questions across eight categories: Dressing and grooming, Arising, Eating, Walking, Hygiene, Reach, Grip, Common daily activities. IL-6 was assessed as exploratory pharmacodynamic parameter from both treatment arms at baseline and week 12.
Treatment-emergent adverse events (TEAEs) and immunogenicity were assessed as safety endpoints. The immunogenicity assessments were performed for the presence of anti-adalimumab antibodies in all patients of both groups at screening, at the end of week 12 and 24 weeks. The immunogenicity sample analysis was performed by using a validated electrochemiluminescence immunoassay. The sensitivity of this assay was 3.3 ng/ml (USFDA recommends of 250 ng/ml to 500 ng/ml Assay Development and Validation for Immunogenicity Testing of Therapeutic Protein Products- Guidance for Industry- draft guidance- April 2016) with an established drug tolerance up to 20 μg/ml at the low surrogate positive control level. The assay performed in a three-tier strategy with initial screening, confirmatory for screening positives. For clinical safety assessment, patients were monitored for clinical signs and symptoms as well as laboratory abnormalities during treatment.
The sample size was estimated assuming the expected ACR response of 57.2% in test adalimumab and 67.2% in reference adalimumab (based on the Statistical Review of Adalimumab. US FDA) . Non-inferiority margin was selected to preserve at least 50% of the placebo deducted effect size of reference product. Placebo deducted effect size of Abbvie’s Humira was 37% (67.2% in HUMIRA/MTX group compared to 30% in placebo group). Non-inferiority margin of 15% preserves 50% of the placebo deducted effect size of Humira. A sample size of at least 105 subjects were sufficient to prove the non-inferiority of Hetero-Adalimumab compared innovator’s Adalimumab with 80% power and 0.05% of level of significance. However, considering the study drop-outs, and Similar biologics 2016 guidelines of CDSCO, India, 168 patients were randomized with an allocation ratio of 2:1, (112 test-adalimumab arm and 56 reference-adalimumab arm).
Efficacy and safety analysis were performed for intention to treat (ITT) and per protocol (PP) population. The ITT population was defined as patients randomized to receive at least one dose of the study medication at baseline and at least one efficacy evaluation available during evaluation period. The PP population included randomized patients who received study medications and completed all study visits as was defined in the protocol without any major protocol deviations. All patients who received at least one dose of the study drug considered for the safety population. For patients who dropped out of the study for any other reason, the last value was carried forward (LOCF) for primary and secondary analyses. The variables measured on continuous scale such as age, height, the mean, standard deviation, median and range were compared using t-test and the proportions like males/female were compared using Fisher’s exact test. ACR individual criteria (i.e. SJC, TJC, PGA, CRP etc.) were presented as absolute values and presented as point estimates at each visit and compared between groups by using t-test. The change in individual ACR criteria from baseline at each subsequent visit compared within the group by using paired t-test. ACR individual criteria compared between the groups by using Analysis of Covariance (ANCOVA). ACR20, ACR50 and ACR70 responder rates were presented as proportions at each visit and compared between groups by using Fishers exact test. The improvement of DAS28 at each week was summarized by treatment group and compared between groups by using t test. The change form baseline to subsequent visits were compared using ANCOVA. The mean HAQ-DI score (total and each category) was calculated at baseline and subsequent visits. These estimates were compared within and between the treatment groups using t-test. ANCOVA was performed to adjust for the differences in the baseline parameters between the treatment groups. Adverse events (AEs) and adverse drug reactions (ADRs) were summarized by system organ class (SOC) and by preferred terms using the Medical Dictionary for Regulatory Activities Terminology (MedDRA). The incidence of serious adverse events (SAEs), ADRs and AEs were compared across the treatment groups using Fisher’s exact test. All statistical tests were performed using SAS® (version 9.3 or higher) system software (SAS Institute Inc., USA).