SOUTH SAN FRANCISCO, Calif. -- September 01, 2026 -- IDEAYA Biosciences said its FDA Type C meeting on IDE849, a DLL3-targeting antibody drug conjugate, produced agreement on a Phase 3 registrational trial design for extensive stage small cell lung cancer (ES-SCLC). The Nasdaq-listed company (IDYA) plans to enroll roughly 400 patients who have already received tarlatamab, randomizing them 1:1 between IDE849 monotherapy and an investigator's choice control arm of topotecan and amrubicin. IDEAYA is targeting trial initiation by year-end 2026.
Trial Design Links Accelerated Approval to Later Survival Data
The Phase 3 study will use overall response rate by blinded independent central review as the primary endpoint supporting a potential accelerated approval, while median overall survival will serve as the primary endpoint for full approval within the same trial. Secondary endpoints include median duration of response by BICR, progression-free survival and safety data. IDEAYA President and CEO Yujiro S. Hata said the company is targeting a randomized Phase 3 study "to enable a potential accelerated approval and full approval in one seamless study design."
Dose-Finding Study Continues to Determine Phase 3 Starting Dose
IDEAYA's ongoing global Phase 1 trial (NCT07174583) is currently evaluating IDE849 at 2.4 mg/kg and 3.5 mg/kg administered intravenously once every three weeks to establish the recommended Phase 3 dose. The trial spans sites in North America, Europe, Australia, South America and Asia, enrolling patients with DLL3-upregulated solid tumors, including SCLC and neuroendocrine carcinoma (NEC).
Partner Hengrui to Present 100-Patient Data Set at ESMO 2026
Clinical updates covering 100 ES-SCLC and NEC patients treated with IDE849 are expected from partner Hengrui at the ESMO 2026 congress, with additional data from IDEAYA's own sponsored Phase 1/2 trial due in the fourth quarter of 2026. IDEAYA said the combined data sets are intended to support a potential best-in-class profile for the ADC ahead of the Phase 3 launch.
AstraZeneca Combination Study Could Reshape First-Line SCLC Strategy
IDEAYA is also testing IDE849 alongside AstraZeneca's PD-L1 inhibitor Imfinzi and its own Phase 1 PARG inhibitor IDE161 to determine whether a first-line SCLC Phase 3 registrational trial is feasible. IDE161 blocks removal of poly(ADP-ribose) chains generated during DNA damage response, a mechanism IDEAYA said could extend the durability of its TOP1-payload ADC pipeline, which also includes the Phase 1 B7H3/PTK7 bispecific candidate IDE034.
DLL3 Target Covers Roughly 53,000 Annual U.S. Cases
IDEAYA estimates annual U.S. incidence of SCLC at approximately 34,000 patients and NEC at approximately 19,000 patients, with DLL3 upregulation also reported in melanoma. The company cited DLL3's limited expression in normal tissue as a rationale for its use as a therapeutic target across these tumor types.