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Clinical Trial
. 2023 May;37(3):433-440.
doi: 10.1007/s40259-023-00582-w. Epub 2023 Mar 7.

Six-Year Survival Outcomes for Patients with HER2-Positive Early Breast Cancer Treated with CT-P6 or Reference Trastuzumab: Observational Follow-Up Study of a Phase 3 Randomised Controlled Trial

Justin Stebbing  1   2   3 , Yauheni Baranau  4 , Valery Baryash  4 , Vladimir Moiseyenko  5 , Dmytro Boliukh  6 , Nicoleta Antone  7 , Alexey Manikhas  8 , Anatolii Chornobai  9 , Taehong Park  10 , Eric Hyungseok Baek  10 , Jaeyong Lee  11 , Jiin Choi  11 , Nahyun Kim  11 , Keumyoung Ahn  10 , Sang Joon Lee  12 , Sunghyun Kim  13
Affiliations
Clinical Trial

Six-Year Survival Outcomes for Patients with HER2-Positive Early Breast Cancer Treated with CT-P6 or Reference Trastuzumab: Observational Follow-Up Study of a Phase 3 Randomised Controlled Trial

Justin Stebbing et al. BioDrugs. 2023 May.

Abstract

Background: The Phase 3 CT-P6 3.2 study demonstrated equivalent efficacy and comparable safety between CT-P6 and reference trastuzumab in patients with human epidermal growth factor receptor-2 (HER2)-positive early breast cancer after up to 3 years' follow-up.

Objective: To investigate long-term survival with CT-P6 and reference trastuzumab.

Methods: In the CT-P6 3.2 study, patients with HER2-positive early breast cancer were randomised to neoadjuvant chemotherapy with CT-P6 or reference trastuzumab, surgery, and adjuvant CT-P6 or reference trastuzumab before a 3-year post-treatment follow-up. Patients who completed the study could enter a 3-year extension (CT-P6 4.2 study). Data were collected every 6 months to assess overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS).

Results: Of 549 patients enrolled in the CT-P6 3.2 study, 216 (39.3%) patients continued in the CT-P6 4.2 study (CT-P6, 107; reference trastuzumab, 109) (intention-to-treat extension set). Median follow-up was 76.4 months for both groups. Medians were not reached for time-to-event parameters; estimated hazard ratios (95% confidence intervals) for CT-P6 versus reference trastuzumab were 0.59 (0.17-2.02) for OS, 1.07 (0.50-2.32) for DFS, and 1.08 (0.50-2.34) for PFS. Corresponding 6-year survival rates in the CT-P6 and reference trastuzumab groups, respectively, were 0.96 (0.90-0.99) and 0.94 (0.87-0.97), 0.87 (0.78-0.92) and 0.89 (0.81-0.94), and 0.87 (0.78-0.92) and 0.89 (0.82-0.94).

Conclusions: Data from this extended follow-up of the CT-P6 3.2 study demonstrate the comparable long-term efficacy of CT-P6 and reference trastuzumab up to 6 years.

Eudract number: 2019-003518-15 (retrospectively registered 10 March 2020).

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Conflict of interest statement

Justin Stebbing has received consulting fees or honoraria (2020–present) from Agenus, Alveo Technologies, APIM Therapeutics, Benevolent AI, Bryologyx, Celltrion, Certis, Eli Lilly, Equilibre Biopharmaceuticals, Graviton Bioscience Corporation, Greenmantle, Heat Biologics, IO Labs, Onconox, Pear Bio, Vaccitech, Volvox, vTv Therapeutics, and Zephyr AI; he has consulted with Lansdowne Partners and Vitruvian; he chairs the Board of Directors for Xerion and previously BB Biotech Healthcare Trust PLC; and is Editor-in-Chief of Oncogene. Taehong Park, Jaeyong Lee, Jiin Choi, Nahyun Kim, Keumyoung Ahn, Sang Joon Lee and Sunghyun Kim are employees of Celltrion, Inc. and hold stock in Celltrion, Inc. Eric Hyungseok Baek is an employee of Celltrion, Inc. Yauheni Baranau, Valery Baryash, Vladimir Moiseyenko, Dmytro Boliukh, Nicoleta Antone, Alexey Manikhas and Anatolii Chornobai have no conflicts of interest to disclose.

Figures

Fig. 1
Fig. 1
Study design
Fig. 2
Fig. 2
Kaplan–Meier plot of OS. (a) ITT set; (b) ITT extension set. CI confidence interval, HR hazard ratio, ITT intention-to-treat, OS overall survival
Fig. 3
Fig. 3
Kaplan–Meier plot of DFS. (a) ITT set; (b) ITT extension set. CI confidence interval, DFS disease-free survival, HR hazard ratio, ITT intention-to-treat
Fig. 4
Fig. 4
Kaplan–Meier plot of PFS. (a) ITT set; (b) ITT extension set. CI confidence interval, HR hazard ratio, ITT intention-to-treat, PFS progression-free survival
See this image and copyright information in PMC

References

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    1. Stebbing J, Baranau Y, Baryash V, Manikhas A, Moiseyenko V, Dzagnidze G, et al. CT-P6 compared with reference trastuzumab for HER2-positive breast cancer: a randomised, double-blind, active-controlled, phase 3 equivalence trial. Lancet Oncol. 2017;18(7):917–928. doi: 10.1016/S1470-2045(17)30434-5. - DOI - PubMed
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    1. Stebbing J, Baranau YV, Baryash V, Manikhas A, Moiseyenko V, Dzagnidze G, et al. 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;188(3):631–640. doi: 10.1007/s10549-021-06240-5. - DOI - PMC - PubMed

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