Abstract PS13-27: Duration of chemotherapy-induced nausea and vomiting (CINV) as a predictor of later-cycle CINV

Background: CINV remains a challenging chemotherapy toxicity, particularly for anthracyclines + cyclophosphamide (AC) for breast cancer. Complete response (CR), defined as no vomiting or use of rescue medication over 5 days after chemotherapy, has been the standard endpoint for successful antiemetic prophylaxis, yet duration of prophylaxis treatment failure (i.e., breakthrough CINV) is rarely assessed. Previous work demonstrated that initial cycle breakthrough CINV is associated with at least one subsequent cycle with CINV (Schwartzberg 2011), and that longer duration CINV is associated with more lost work time and impaired activity (Schwartzberg ASCO 2020). We sought to evaluate the duration of breakthrough CINV in cycle one and its association with individual patients’ repeat breakthrough CINV in subsequent cycles. Methods: Days of CINV was a prespecified endpoint in a prospective, 4-cycle CINV prophylaxis trial of combination netupitant/palonosetron (NEPA) + dexamethasone (Dex) for patients with breast cancer receiving AC; the primary endpoint was CR. Patients without CR were classified as prophylaxis treatment failure (TF) and categorized as short TF (sTF, 1-2 days) or extended TF (xTF, ≥3 days), consistent with work by Ballatori [2006] and Roeland [2019]. We analyzed patients’ sequences of CR, sTF, and xTF for cycles 1-4 and assessed likelihood of CR for cycles 2-4 based on cycle 1 TF duration, using chi-square statistics. Results: Of 402 patients in cycle 1, 303 had CR and 99 (24.6%) had TF. Duration of TF in cycle 1 was sTF for 48 patients while 51 patients had xTF. Patients with sTF in cycle 1 often experienced CR in cycle 2 (32/46 remaining patients; 69.6%) while patients with xTF in cycle 1 often had TF in cycle 2 (38/49; 77.6%). Patients had >84% likelihood of repeating their cycle 2 outcome (CR or TF) in cycles 3 and 4. Over all cycles, those with sTF in cycle 1 had CR in 75/108 later cycles (69.4%) while xTF in cycle 1 led to CR in 32/105 later cycles (29.0%), p Citation Format: Rudolph M. Navari, Gary Binder, Eric J. Roeland, Alexander Molassiotis, Kathryn J. Ruddy, Thomas W. LeBlanc, Dwight D. Kloth, Silvia Sebastiani, Marco Turini, Luke M. Schmerold, Xing Liu, Lee Schwartzberg. Duration of chemotherapy-induced nausea and vomiting (CINV) as a predictor of later-cycle CINV [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 PS13-27.