Neoadjuvant carboplatin/taxane (CbT) with or without doxorubicin/cyclophosphamide (AC) in real-world patients with early triple negative breast cancer (TNBC).

e23347 Background: Treatment (tmt) of early-stage TNBC has changed over the past several years with Cb becoming a standard addition to AC-T. Whether AC should remain as part of the chemotherapy backbone is unclear. We report factors associated with tmt selection and response in patients (pts) receiving neoadjuvant CbT±AC. Methods: Electronic health records extracted for member sites of the Greater Plains Collaborative (GPC), a Patient Centered Outcomes Research (PCOR)net-funded Clinical Research Network, are transformed and linked with their North American Association of Central Cancer Registries (NAACR)-formatted hospital cancer registry data to form an interoperable, deidentified real-world data resource. Following a federally funded, IRB-approved protocol, we identified adult female pts diagnosed (dx) 2014-2022 with first, primary, stage I-III TNBC, initiating chemotherapy within 4 months of dx at 10 academic healthcare systems of the GPC network. Drug codes, administration dates, and surgery date were extracted from EHR data to identify pts receiving neoadjuvant CbT±AC. Tmt response examined at time of surgery was extracted from the NAACCR “Response to Neoadjuvant Therapy” variable and classified as complete (pCR) or not. 126 pts with “response to treatment, but not noted if complete or partial” were all categorized as not having pCR, to provide the most conservative estimate. Those with missing or unknown response were excluded from the cohort. Descriptive statistics were used to characterize the sample and multivariable logistic models to test the association between tmt group (grp) and pCR, controlling for age, stage, and use of pembrolizumab (pembro). Results: 292 and 362 pts received neoadjuvant CbT and CbT+AC, respectively. 17% were black. Compared to CbT, the CbT+AC grp was younger (47 v 54, p < 0.01), higher stage (40% v 26% stage III, p < 0.01), and more likely to receive pembro (37% v 11%, p < 0.01). The two grps did not differ by race, BMI, grade or comorbidity. pCR was observed in 49% of the CbT grp and 50% of the CbT+AC grp. On multivariable analysis, pembro was associated with pCR (OR = 1.55, 95%CI 1.05-2.30, p = 0.03). Stage was also associated with pCR (OR = 0.60, 95%CI 0.38-0.94, p = 0.03 for stage II v I; OR = 0.34, 95%CI 0.20-0.55, p < 0.01 for stage III v I). Odds of pCR was not statistically significantly different between pts who received CbT v CbT+AC (OR = 1.04, 95%CI 0.73-1.47, p = 0.80). Conclusions: In this retrospective, observational study of real-world pts, the addition of AC to CbT was not associated with better tmt response. As expected, pembro independently predicted odds of pCR. Pts receiving CbT were older than those who received more-intense therapy (CbT+AC). We anticipate results from the ongoing SCARLET trial to confirm whether some pts could be spared the toxicity and late effects of AC.