Abstract 145P
Background
Neoadjuvant chemotherapy (NACT) with pembrolizumab followed by adjuvant pembrolizumab has become standard of care for early, triple-negative breast cancer (TNBC). Improved outcomes are offset by increased toxicity. Real-world data on the impact of addition of pembrolizumab to chemotherapy is lacking.
Methods
In this multi-institutional, retrospective analysis, data from patients who started NACT/pembrolizumab for TNBC between May 2022 - Dec 2023 were reviewed. We assessed dose modifications, toxicities, immune-related adverse events (irAE) and clinical outcomes.
Results
78 patients received pembrolizumab plus neoadjuvant carboplatin-paclitaxel and epirubicin-cyclophosphamide. Pembrolizumab was omitted in 30 (38%) patients; 19 (63%) of these had more than 1 dose omission. NACT dose reductions were required for 39 patients (50%). Most common toxicity affecting patients resulting in dose reduction were fatigue (n=11), peripheral neuropathy (n=10), gastrointestinal (n=9) and myelosuppression (n=8). Only 6.7% of all adverse events were ≥ grade 3. Steroids were prescribed in 19 (24%) of patients to manage the following grade 3 irAE: dermatological (n=7), liver transaminitis (n=7), endocrinopathies (n=3), nephritis, colitis, pneumonitis, and musculoskeletal toxicity (all n=1). Median time to NACT completion was extended beyond the expected 168 days for 11 patients (29.7%) by a median of 10 days. NACT was terminated early in 5 patients due to toxicity. Among 38 patients who completed surgery complete pathological response (pCR) was achieved in 68.4%. Patients missing even 1 dose of pembrolizumab had higher non-pCR rate (41.2%) than those who received all doses (23.8%), but this was not statistically significant (p=0.13). The rate of non-pCR was similar between those who did (40%) and did not (36.8%) have NACT dose reductions.
Conclusions
Introduction of pembrolizumab resulted in additional toxicity, frequent dose reductions and delays in chemotherapy delivery. Frequent omission of immunotherapy doses highlights the complexity of managing toxicities arising from use of this new agent class.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
F. Raja: Financial Interests, Personal and Institutional, Other, Consultancy and symposium support: Novartis, AstraZeneca, Daiichi Sankyo, Eli Lilly, Pfizer, Gilead, Roche, MSD. A. Sheri: Financial Interests, Personal and Institutional, Other, Honoraria: BMS, Roche, Pfizer, AstraZeneca. A.A. Konstantis: Financial Interests, Personal, Other, Honoraria: Pfizer, Gilead. E. Papadimitraki: Financial Interests, Personal and Institutional, Other, Honoraria: Novartis, Lilly, Gilead, AstraZeneca, Roche, Eisai, Pfizer; Financial Interests, Personal and Institutional, Sponsor/Funding, Registration sponsorship: MSD, Novartis, Lily. All other authors have declared no conflicts of interest.