Poster display session: Breast cancer - early stage, locally advanced & metastatic, CNS tumours, Developmental therapeutics, Genitourinary tumours - prostate & non-prostate, Palliative care, Psycho-oncology, Public health policy, Sarcoma, Supportive care Poster Display session

217P - Subgroup analyses of efficacy from a phase III study comparing SB3 (trastuzumab biosimilar) with reference trastuzumab in early breast cancer patients

Presentation Number
217P
Lecture Time
12:45 - 12:45
Speakers
  • Javier Cortes Castan (Barcelona, ES)
Location
Hall A3 - Poster Area Networking Hub, ICM M√ľnchen, Munich, Germany
Date
22.10.2018
Time
12:45 - 13:45

Abstract

Background

SB3 has been approved by the European Commission as a biosimilar of reference trastuzumab (TRZ). Equivalence for efficacy between SB3 and TRZ based on breast pathologic complete response (bpCR) rates has been demonstrated and previously reported.1 Here we report results of subgroup analyses of efficacy by baseline disease characteristics and demographics.

Methods

Patients received either SB3 or TRZ for 8 cycles concurrently given with chemotherapy (docetaxel followed by 5-fluorouracil/epirubicin/cyclophosphamide). Then patients underwent surgery followed by 10 cycles of SB3 or TRZ. The primary endpoint was bpCR rate. Subgroup analyses of bpCR rate, total pathologic complete response (tpCR) rate, and overall response rate (ORR) by region, age, ethnicity, hormone receptor status, breast cancer type, and menopausal status was performed.

Results

800 patients (SB3, n = 402; TRZ, n = 398) were included in the per-protocol set (PPS). The bpCR rates were 51.7% for SB3 and 42.0% for TRZ with adjusted difference of 10.70% (95% CI, 4.13, 17.26). Subgroup analysis results are provided in the table. A trend of favourable efficacy of SB3 compared to TRZ was maintained in most of subgroup analyses. Similar trends were observed in the subgroup analysis of tpCR rate and ORR. Table: bpCR rates by baseline demographics and disease characteristics.

SB3 n/n’ (%)TRZ n/n’ (%)Adjusted difference (%) (SB3-TRZ, 95% CI)
Region
Europe53/108 (49.1)44/98 (44.9)3.44 (-9.63, 16.51)
Non-Europe155/294 (52.7)123/300 (41.0)13.18 (5.59, 20.77)
Age
Age <4559/121 (48.8)48/119 (40.3)9.20 (-3.08, 21.48)
Age ≥45149/281 (53.0)119/279 (42.7)11.51 (3.76, 19.26)
Ethnicity
Asian68/124 (54.8)51/124 (41.1)15.52 (4.27, 26.78)
White135/269 (50.2)112/264 (42.4)8.45 (0.28, 16.62)
Hormone receptor status
ER and/or PR positive119/254 (46.9)78/230 (33.9)12.87 (4.45, 21.28)
ER and PR negative89/148 (60.1)89/168 (53.0)7.34 (-3.14, 17.83)
Breast cancer type
Operable120/241 (49.8)97/238 (40.8)10.14 (1.44, 18.85)
Locally advanced88/161 (54.7)70/160 (43.8)11.53 (1.58, 21.48)
Menopausal status
Yes105/198 (53.0)92/198 (46.5)7.65 (-1.33, 16.64)
No103/204 (50.5)75/200 (37.5)12.97 (3.81, 22.14)

CI, confidence interval; ER, oestrogen receptor; PR, progesterone receptor; n, number of patients achieving bpCR; n’, number of patients with available assessment results.

Conclusions

Subgroup analysis results of bpCR, tpCR, and ORR showed a tendency of favourable efficacy in SB3 compared to TRZ, which were consistent with the overall bpCR analysis result. Reference: 1. Pivot X et al. J Clin Oncol. 2018; 36:968-74.

Clinical trial identification

EudraCT: 2013-004172-35.

Legal entity responsible for the study

Samsung Bioepis Co., Ltd.

Funding

Samsung Bioepis Co., Ltd.

Disclosure

J. Cortes Castan: Honoraria: Roche, Novartis, Eisai, Celgene, Pfizer; Consulting/advisor: Roche, Celgene, Aztrazeneca, Cellestia Biotech, Biothera, Merus. X. Pivot: Principle investor: phase III study of SB3; Consultant and honoraria: Samsung Bioepis. G. Curigliano: Fee for a seminar on the abstract. S. Song, Y.C. Yoon: Employment: Samsung Bioepis. All other authors have declared no conflicts of interest.

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