Abstract P2-12-05: Efficacy of neoadjuvant systemic carboplatin therapy in triple-negative breast cancer

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Abstract Background. Guidelines recommend broad use of carboplatin (CBDCA) for neoadjuvant therapy (NACT) of patients with triple negative breast cancer (TNBC). However, current evidence is contradictory. The aim of this prospective observational study was to assess efficacy and feasibility of CBDCA-containing neoadjuvant therapy in clinical routine. Patients and Methods. Patients who received NACT for early TNBC (n=150) were consecutively enrolled between 2000 and 2021. The following regimens were used: dose-dense epirubicin-cyclophosphamide (ddEC) followed by taxanes (n=62); CBDCA-taxane combination followed by ddEC (n=49), CBDCA-taxane combination, no anthracyclines (n=25), other chemotherapy regimen (n=14). Some CBDCA therapies were given every 3 weeks (n=18), the majority was given in a weekly fashion (n=56). The efficacy and feasibility including toxicities of these carboplatin regimen were analyzed. Median follow-up iDFS: 36.2 months (6-154), median Follow-up OS 39.3 months (6-214).Primary objective was the pCR rate (ypT0 N0) in patients who were treated with CBDCA in comparison to those who received standard non-platinum containing NACT. Secondary objectives were toxicity, therapy adherence, cancer associated recurrences and association of pCR rate with invasive disease-free survival (iDFS) and overall survival (OS). Results. Half of the patients (n=74) were treated with CBDCA, two third (69%) of them received the complete intended cycles if necessary with primary GCSF-support. Overall, the addition of CBDCA slightly increased the pCR rate from 43.4% to 48.6% with a 1.8 times reduced risk for iDFS events. The highest pCR rate was observed in those patients (n=50) who had received all CBDCA-courses as planned (50% vs 45%). By 48 months, pCR with CBDCA treatment was associated with an improved course of the disease (86.3 % iDFS probability), followed by non-pCR and CBDCA-therapy (81.1% iDFS probability), pCR and no platinum (79.8%) and non-pCR and no platinum (70.7%). Considering OS, patients without CBDCA and no pCR had the highest mortality (19.5%), all other groups had over 90% OS-probability. Dose-modification of CBDCA was associated to pCR (4 of 5 patients), whilst with discontinuation of CBDCA, 12 of 20 patients had residual disease. Although neutropenia, thrombocytopenia or anemia occurred in 36 patients, CBDCA discontinuation due to hematological effects was only necessary in 10 cases. Conclusion. In our prospective cohort, the addition of CBDCA to neoadjuvant chemotherapy for patients with TNBC was highly effective. Even after dose-modification of CBDCA (e.g. for toxicity) it seems to be effective compared to discontinuation or no inclusion of CBDCA. Our data support the current recommendations to include CBDCA in neoadjuvant therapy for TNBC. Citation Format: Christoph Thomssen, Kathleen Schüler, Marcus Bauer, Kristin Reinhardt, Hans-Gerorg Strauß, Martina Vetter. Efficacy of neoadjuvant systemic carboplatin therapy in triple-negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-12-05.