IDEAYA Biosciences Inc (IDYA.O) IDE849's 17.4-Month 2L mOS and Global Safety Update Further Strengthen Competitive DLL3 ADC Profile

Citi comments on IDYA/Hengrui's updated IDE849 Ph1 data, which further strengthen the competitive profile outlined in the prior ESMO note, with the newly reported 17.4-month 2L mOS landing at the favorable end of the mid-to-high-teens range implied by the prior 66.4% 12-month landmark OS. Median PFS and cORR in 2L were 6.9 months and 60.8%, in-line with prior disclosure; in 2L+ SCLC management noted a 14.7-month mOS and 54.5% cORR. Management also shared preliminary safety from the Ph1 global trial, with 5% Gr3+ TRAEs at 2.4 mg/kg across 20 patients vs. 22.2% at 3.5 mg/kg across 18 patients, while Gr3+ ILD was 0.8% across all 122 treated patients and doses. The early global comparison favors 2.4 mg/kg, though dose-specific efficacy, mDOR, exposure and the YE26/early-2027 global update remain necessary for RP3D selection and the post-IMDELLTRA Ph3 strategy. Maintain Buy/High Risk with a US$65 target price, implying 87.3% expected total return from US$34.71.