Abstract P2-12-13: Pathologic complete response rate according to the carboplatin dose in patients with non-metastatic HER2+ breast cancer treated with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP)

Abstract

Abstract Purpose In the patients treated with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) regimen, grade 3-4 anemia occurs frequently during the treatment course. Anemia develops mainly by cytotoxic drug including carboplatin. By contrast, dose reduction of carboplatin could raise concerns about the oncologic outcome. We compared the pathologic complete response (pCR) rate and grade 3-4 anemia/transfusion rate according to the dose of carboplatin among the patients undergoing neoadjuvant TCHP. Method We retrospectively analyzed 294 patients who treated with neoadjuvant TCHP between Apr 1, 2015 and Dec 31, 2020. Clinicopathological features were collected by electronic medical record review. Hemoglobin levels were measured at baseline, before each cycle of chemotherapy, and after the chemotherapy completion. Multivariable binary logistic regression analysis was performed to identify predictive factors for grade 3-4 anemia and transfusion event. Result In a total of 294 patients, neoadjuvant TCHP with carboplatin AUC6 were initiated in 234 (79.6%, 234 of 294), whereas upfront carboplatin AUC5 were concurrently administered in 60 (20.4%, 60 of 294). There was no statistical difference in the pCR rate between the two groups (70.9% in the AUC6, 80.0% in the AUC5; p=0.159). In the both ER+ and ER-, there were no significant differences between the AUC6 and AUC5 (54.3% and 50.0% in the ER+; 81.7% and 86.0% in the ER-). Tumor and nodal stage were not different between the two groups. The AUC5 group had less grade 3-4 anemia (18.3%, 11 of 60 vs 34.2%, 80 of 234) and transfusion event (10.0%, 6 of 60 vs 21.8%, 51 of 234) compared with the AUC6 group. Multivariable analysis demonstrated that baseline hemoglobin level under 12g/dL and ≥2g/dL hemoglobin down after first chemotherapy are independent risk factors for grade3-4 anemia or blood transfusion before surgery. Conclusion The pCR rate was not different according to the initial carboplatin dose in the HER2+ breast cancer treated with neoadjuvant TCHP. We suggest that the dose of carboplatin could be optimized as AUC5 to reduce TCHP-induced anemia and transfusion rate among Asian HER2-positive breast cancer patients treated with TCHP. Baseline low hemoglobin level under 12 g/dL or rapid hemoglobin down after first cycle are risk factors for TCHP-induced anemia. Table 1.The pathologic complete response (pCR) rate, distribution of anemia grade and transfusion rate according to AUCVariablesAUC6AUC5TotalP-valueOverall (N=294)0.159pCR166 (70.9%)48 (80.0%)214 (72.8%)Non-pCR68 (29.1%)12 (20.0%)80 (27.2%)Total234 (100.0%)60 (100.0%)294 (100.0%)ER-positive (N=102)0.793pCR50 (54.3%)5 (50.0%)55 (53.9%)Non-pCR42 (45.7%)5 (50.0%)47 (16.1%)Total92 (100.0%)10 (100.0%)102 (100.0%)ER-negative (N=192)0.487pCR116 (81.7%)43 (86.0%)159 (82.8%)Non-pCR26 (18.3%)7 (14.0%)33 (17.2%)Total142 (100.0%)50 (100.0%)192 (100.0%)Anemia grade (N=294)0.0181 or 2154 (65.8%)49 (81.7%)203 (69.0%)3 or 480 (34.2%)11 (18.3%)91 (31.0%)Transfusion (N=294)0.039No183 (78.2%)54 (90.0%)237 (80.6%)Yes51 (21.8%)6 (10.0%)57 (19.4%) Citation Format: Jung Hwan Ji, Soong June Bae, Seul-Gi Kim, Min Hwan Kim, Gun-Min Kim, Joohyuk Sohn, Jee Hung Kim, Sung Gwe Ahn, Joon Jeong. Pathologic complete response rate according to the carboplatin dose in patients with non-metastatic HER2+ breast cancer treated with neoadjuvant docetaxel/carboplatin/trastuzumab/pertuzumab (TCHP) [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 P2-12-13.