Abstract

12118 Background: The efficacy and safety profile of T-DXd has been established in patients (pts) with various tumor types, and nausea and vomiting are the most common treatment-emergent adverse events (TEAEs). T-DXd study protocols were refined over time to recommend prophylaxis (eg, neurokinin or serotonin receptor antagonists and/or steroids) before T-DXd treatment, in line with antiemetic and institutional guidelines. We conducted a pooled, post hoc analysis capturing safety information across tumor types; we report results on nausea and vomiting. While this analysis was not designed to assess antiemetic effectiveness, it reveals the incidence of nausea and vomiting in clinical trials of T-DXd 5.4 mg/kg in more detail across a large dataset. Methods: 1449 pts treated with ≥1 dose of 5.4 mg/kg T-DXd (every 3 wks) were included from 7 phase 1-3 clinical trials in metastatic HER2+ and HER2-low breast cancer, HER2+ gastric cancer, and HER2-mutant non–small cell lung cancer (DESTINY-Breast01, -Breast02, -Breast03, -Breast04, -Lung01, -Lung02, and the first-in-human phase 1 study J101 in multiple tumor types; study enrollment starting 2015-2021). Regardless of antiemetic use (including prophylaxis), the incidence, severity, time to onset, and duration of nausea and vomiting TEAEs were assessed along with event outcomes. Results: Of 1449 pts receiving T-DXd 5.4 mg/kg (median [range] number of 3-wk treatment cycles: 13 [1-60]), 74.6% (n=1081) experienced nausea, and 41.6% (n=603) reported vomiting. Most pts had grade 1/2 nausea (41.2%/27.6%) and/or vomiting (26.2%/12.8%). Grade 3 TEAEs of nausea were reported in 5.8% of pts, with grade ≥3 TEAEs of vomiting observed in 2.6% of pts. By the data cutoff for each trial, 66.9% of pts with nausea and 87.6% with vomiting had their symptoms resolve. Most pts who experienced nausea and vomiting did so during the initial 21 days (cycle 1; n=879 [81.3%] and 336 [55.7%], respectively; 35.8% of all pts received antiemetic prophylaxis at cycle 1); both TEAEs declined notably in subsequent cycles. Rates of drug discontinuation, dose reduction, and drug interruption due to nausea and vomiting were generally low (Table). Conclusions: Most nausea and vomiting events were reported during the first 3 wks of treatment and resolved. Appropriate prophylaxis of nausea and vomiting is a key management strategy and allows pts to benefit from longer treatment durations with T-DXd. Ongoing studies are exploring the implementation and impact of prophylaxis for T-DXd–related emesis. Clinical trial information: NCT03248492 , NCT03523585 , NCT03529110 , NCT03734029 , NCT03505710 , NCT04644237 , NCT02564900 . [Table: see text]