Abstract PS10-38: Real Would Evidence (RWE) of neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) in patients with HER2 positive early or locally advanced breast cancer treated Single institutional experience

Introduction Adding pertuzumab(P) on trastuzumab(H) with cytotoxic chemotherapy increased pathologic complete response (pCR) of early or locally advanced HER2 positive breast cancer (EBC) with neoadjuvant chemotherapy. Since 63.6% of pCR rate has been reported from TRYPHAENA trial, TCHP regimen has been used as a standard of neoadjuvant treatment regimen for patients with HER2 positive EBC. However, this regimen has profound toxicities in terms of myelosuppression, neurotoxicity, and etc. Furthermore we still need more information on clinical outcomes and toxicities with this regimen. Therefore, we report real world experience of EBC patients treated with neoadjuvant TCHP followed by curative surgery. Methods We retrospectively reviewed electronic medical record of EBC patients who received neoadjuvant TCHP. Information which we gathered included patients’ and tumor characteristics at the time of diagnosis, details of neoadjuvant chemotherapy, pathologic assessment of tumor response to neoadjuvant TCHP and recurrence free survival after curative surgery. pCR was defined as absence of residual invasive cancer on pathologic evaluation of the resected breast specimen and all sampled regional lymph nodes (ypT0/isN0). Results Between February 2016 and August 2019, 447 patients were treated with neoadjuvant TCHP followed by curative surgery. Median age at BC diagnosis was 56. In clinical stage, stage II was 54.6% and 45.4% of stage III and hormone receptor (HR) positive BC was 48.3%. Most commonly reported adverse event(AE) was mucositis (84%) followed by diarrhea (77%). In terms of Grade 3 AE, anorexia(6%), diarrhea(2%) were frequently observed and 9(2%) of febrile neutropenia occurred despite of prophylactic use of peg-filgrastim. Forty percent of patients experienced dose reduction due to AEs. Of 447 patients, 29% of patients underwent total mastectomy and 71% of breast conserving surgery. In terms of clinical outcome, pCR rate was 64%; 77% of HR negative BCs and 50% of HR positive BCs. Among baseline characteristics, high nuclear grade, high histologic grade, HR stats affected to pCR status (Ps Key words: neoadjuvant chemotherapy, HER2+ breast cancer, pertuzumab, pathologic complete response Citation Format: Ji-Yeon Kim, Seok Jin Nam, Seok Won Kim, Jonghan Yu, Byung Joo Chae, Se Kyung Lee, Jai Min Ryu, Jin Seok Ahn, Young-Hyuck Im, Yeon Hee Park. Real Would Evidence (RWE) of neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) in patients with HER2 positive early or locally advanced breast cancer treated Single institutional experience [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-38.