CT-P42 Comparable to Reference Aflibercept in DME Treatment, Study Finds

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Results from the CT-P42 3.1 Study indicate the therapeutic equivalence of the aflibercept biosimilar, CT-P42, to the reference product in eyes with DME.

CT-P42, a proposed aflibercept biosimilar, was therapeutically equivalent to the reference product at 8 weeks in the treatment diabetic macular edema (DME), according to new findings.1

The research, presented at the American Society of Retina Specialists (ASRS) 41st Annual Meeting, showed comparable vision gains from baseline and an overall well-tolerated profile in nearly 200 eyes with DME treated with CT-P42.

“It’s similar to what we expect with aflibercept in both anatomy and visual acuity,” said presenting author David M. Brown, MD, Retina Consultants of Texas. “It was well-tolerated, with no difference in safety profiles, and a low incidence of anti-drug antibodies (ADAs) in both groups.”

CT-P42 3.1 is an ongoing, randomized, double-masked, active-controlled phase 3 study, evaluating the efficacy and safety of biosimilar aflibercept compared to the reference product in patients with DME.2

Patients meeting inclusion criteria were 18 years or older with type 1 or type 2 diabetes and had DME in the center of the macular, central subfield retinal thickness of ≥350 µm, and a BCVA of 73 to 34 using ETDRS charts (Snellen equivalent 20/40 to 20/200). Patients were required to have 2 good eyes, no previous treatment with anti-VEGF in the study eye, and no anti-VEGF treatment in the fellow eye for 6 months.

A total of 348 patients met inclusion criteria and were randomized in the analysis: 173 were treated with 2mg CT-P42 and 175 patients were treated with 2mg reference aflibercept. Demographic and baseline characteristics were well-balanced between study groups.

The primary study endpoint was to demonstrate the similarity between CT-P42 and reference aflibercept, with the mean change from baseline in best-corrected visual acuity (BCVA) at Week 8. In lieu of a 52-week endpoint, regulatory agencies indicate an 8-week time point is the best to be sensitive if the biosimilar was not as effective as the reference product. Key secondary endpoints, including additional efficacy, pharmacokinetics, usability, and overall safety and immunogenicity, were measured at week 52.

Upon analysis, investigators found the primary endpoint was met, with the 95% confidence interval (CI) for the estimate of treatment difference entirely within the predefined equivalence margin of ±3 letters.1

Patients treated with CT-P42 gained 9.43 letters versus 8.85 for reference aflibercept in the full analysis. The estimated treatment difference was 0.58 (95% CI, -0.73 to 1.88). In the per-protocol analysis, the gains were 9.22 for CT-P42 and 8.84 for reference aflibercept, with an estimated treatment difference of 0.38 (95% CI, -0.95 to 1.66).

Secondary efficacy endpoints showed similar results in mean BCVA improvement between the 2 treatment groups up to Week 24. Additionally, the mean change from baseline in central subfield thickness (CST) showed comparable improvement in both groups, as did ≥2-step improvement from baseline in ETDRS DRSS scores.

Safety analyses showed a well-tolerated profile similar to the reference product up to Week 24. Low rates of ocular treatment-emergent adverse events (≥1% in any arm) were observed in both treatment groups.

In addition, rates of adverse events, including intraocular inflammation, were low in both groups, with no observed retinal vasculitis. Immunogenicity data showed the proportion of patients with anti-drug antibodies was low, and did not increase over time, with no notable difference between the 2 groups.


  1. Efficacy and Safety of CT-P42 Compared to Reference Aflibercept (AFL) in Diabetic Macular Edema (DME): 24-Week Results From the Phase 3 CT-P42 3.1 Study. Paper presentation at the American Society of Retina Specialists 41st Annual Meeting. July 28 - August 1.
  2. Study to compare efficacy and safety of CT-P42 in comparison with eylea in patients with diabetic macular edema - full text view. Accessed August 18, 2023.