Abstract P1-01-03: The Impact of Comorbid HIV infection on Neoadjuvant and Adjuvant Chemotherapy Relative Dose Intensity in South African Breast Cancer Patients

Abstract Introduction In the South African Breast Cancer and HIV Outcomes (SABCHO) study, early-stage breast cancer patients living with HIV, compared to their HIV-negative counterparts, demonstrated higher overall mortality and lower rates of pathologic complete response if treated with neoadjuvant chemotherapy. We aimed to determine if comorbid HIV also impacted receipt of timely and complete neoadjuvant and adjuvant chemotherapy. Methods We retrospectively identified Black, stage I-III SABCHO participants diagnosed with breast cancer from June 2015 to July 2019 and who received at least 2 doses of neoadjuvant or adjuvant chemotherapy at either Charlotte Maxeke Johannesburg Academic Hospital (Gauteng) or Grey’s Hospital (KwaZulu-Natal). Data on the originally prescribed chemotherapy regimen and the dose and timing of all received chemotherapy was extracted from patients’ medical records, as well as values from all complete blood counts and metabolic panels performed during treatment. Relative dose intensity (RDI) was calculated for each agent in the prescribed regimen with the mean RDI of all agents representing the RDI of the full regimen. We assessed for associations between full regimen RDI and HIV status using a multivariable linear regression model that included demographic and clinical covariates also shown to impact RDI. We also compared rates of myelosuppression, alkaline phosphatase elevation, and creatinine elevation using linear regression. Using previously collected survival data, we compared overall mortality based on overall RDI above or below 0.85. Results We analyzed data from 325 eligible subjects, 166 of whom were living with HIV. No differences based on HIV status were appreciated in the prescribed chemotherapy regimens. For women without HIV median RDI was 0.87 (interquartile range (IQR) 0.77-0.94) and, in those living with HIV, it was 0.89 (IQR 0.77-0.95). HIV status showed no significant association with RDI on multivariable analysis, and the only patient characteristics associated with RDI were estrogen/progesterone receptor (ER/PR) and HER2 status. Patients living with HIV experienced more CTCAE v5.0 grade 3+ anemia and leukopenia than those without HIV (anemia: 10.8% vs 1.9%, p=0.001; leukopenia: 8.4% vs 1.9%, p=0.008) and were more likely to receive at least one dose of filgrastim (24.7% vs 10.7%, p=0.001). Receipt of RDI greater or less than 0.85 did not predict overall mortality in the full cohort or HIV status subgroups. A trend towards improved survival with RDI greater than 0.85 was seen among the 69 participants with ER/PR negative disease (hazard ratio: 0.60, 95% confidence interval: 0.30-1.21, p = 0.15). Conclusions Neoadjuvant and adjuvant chemotherapy RDI did not differ by HIV status among women in the SABCHO study, although women living with HIV experienced more myelotoxicity during treatment. Efforts to reduce chemotherapy dose reduction and delays should target all South African breast cancer patients. Citation Format: Daniel S. O’Neil, Oluwatosin A Ayeni, Hayley A. Farrow Woolridge, Wenlong Carl Chen, Georgia Demetriou, Ines Buccimazza, Sharon Cacala, Maureen Joffe, Michael Antoni, Gilberto Lopes, Yoanna Pumpalova, Witness Mapanga, Judith S. Jacobson, Katherine D. Crew, Alfred I. Neugut, Paul Ruff, Herbert Cubasch. The Impact of Comorbid HIV infection on Neoadjuvant and Adjuvant Chemotherapy Relative Dose Intensity in South African Breast Cancer Patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-01-03.