Long-term efficacy and safety of CT-P6 versus trastuzumab in patients with HER2-positive early breast cancer: final results from a randomized phase III trial

Breast Cancer Res Treat. 2021 Aug;188(3):631-640. doi: 10.1007/s10549-021-06240-5. Epub 2021 Jun 20.

Abstract

Purpose: Equivalent efficacy was demonstrated for the biosimilar CT-P6 and trastuzumab following neoadjuvant therapy for patients with human epidermal growth factor receptor-2 (HER2)-positive early breast cancer. Following adjuvant treatment, efficacy and safety were comparable between treatments. We report updated safety and efficacy data after up to 3 years' follow-up.

Methods: Following neoadjuvant chemotherapy with CT-P6/trastuzumab, patients underwent surgery and continued receiving adjuvant CT-P6/trastuzumab. The primary endpoint (previously reported) was pathological complete response. Time-to-event analyses (disease-free survival [DFS], progression-free survival [PFS], and overall survival [OS]), study drug-related and cardiac adverse events, and immunogenicity were assessed during post-treatment follow-up.

Results: Most patients entered the follow-up period (CT-P6: 259 [95.6%]; trastuzumab: 269 [96.8%]). After a median follow-up of 38.7 (CT-P6) and 39.6 (trastuzumab) months, medians were not reached for time-to-event parameters; estimated hazard ratios (HRs) and 3-year survival rates were similar between groups. Estimated HRs (95% confidence intervals) for CT-P6 versus trastuzumab were 1.23 (0.78-1.93) for DFS, 1.31 (0.86-2.01) for PFS, and 1.10 (0.57-2.13) for OS (intention-to-treat population). Safety findings were comparable between groups for the overall study and follow-up period, including study drug-related cardiac disorders (CT-P6: 22 [8.1%] patients; trastuzumab: 24 [8.6%] patients [overall]) and decreases in left ventricular ejection fraction. Immunogenicity was similar between groups.

Conclusion: The similarity of the time-to-event analyses between CT-P6 and trastuzumab supports the equivalence in terms of efficacy established for the primary endpoint. CT-P6 was well tolerated, with comparable safety and immunogenicity to trastuzumab. ClinicalTrials.gov: NCT02162667 (registered June 13, 2014).

Keywords: Adjuvant therapy; Biosimilar; CT-P6; HER2-positive early breast cancer; Neoadjuvant therapy; Trastuzumab.

Publication types

  • Clinical Trial, Phase III
  • Randomized Controlled Trial

MeSH terms

  • Antineoplastic Combined Chemotherapy Protocols
  • Biosimilar Pharmaceuticals* / therapeutic use
  • Breast Neoplasms* / drug therapy
  • Chemotherapy, Adjuvant
  • Female
  • Humans
  • Receptor, ErbB-2 / genetics
  • Stroke Volume
  • Trastuzumab / adverse effects
  • Ventricular Function, Left

Substances

  • Biosimilar Pharmaceuticals
  • CT-P6
  • Receptor, ErbB-2
  • Trastuzumab

Associated data

  • ClinicalTrials.gov/NCT02162667