IDEAYA Biosciences Achieves 17.4-Month Median OS with IDE849 ADC in Relapsed SCLC

With two Phase 3 registrational trials now in targeting range following successful FDA Type C meetings, IDEAYA Biosciences' IDE849 (SHR-4849) is moving from proof-of-concept into the scale-up and manufacturing planning phase that will test CDMOs specializing in oncology ADC production. Updated Phase 1 data presented by partner Jiangsu Hengrui Pharmaceuticals at ESMO Congress 2026 provide the clinical foundation for that transition.

The Hengrui China study, with an August 21, 2026 data cutoff and 122 enrolled patients, reported a median overall survival of 17.4 months in second-line SCLC (n=51) and 14.7 months across second-line and later settings (n=101). ORR reached 72.5% and confirmed ORR 60.8% in the 2L cohort, with a 6.9-month median PFS. In patients with brain metastases, ORR was 76.9% (20/26), a signal with direct implications for trial design and endpoint selection in the planned registrational studies.

Efficacy extended to neuroendocrine carcinomas, where IDE849 produced a 52.6% ORR and an 82.4% nine-month OS rate in 19 NEC patients, supporting IDEAYA's intent to pursue a second Phase 3 program in that indication. The DLL3-targeted, TOP1-inhibitor payload construct is the same across both indications, meaning manufacturing process validation and conjugation consistency will need to accommodate two concurrent late-stage programs.

The safety profile at the 2.4 mg/kg expansion dose showed a Grade ≥3 treatment-related adverse event rate of 33.3%, a treatment-related discontinuation rate of 2.5%, and a Grade ≥3 interstitial lung disease rate of 0.8% across the full study population. In IDEAYA's separate global clinical study, Grade ≥3 TRAE rates of 5% at 2.4 mg/kg and 22.2% at 3.5 mg/kg have been observed, data points that will inform dose selection and risk management protocols in the registrational design.

For CDMOs and internal manufacturing leads, the DLL3-TOP1 conjugate architecture presents specific process challenges: TOP1 inhibitor payloads require contained handling, and drug-to-antibody ratio consistency is a known quality attribute under scrutiny during 21 CFR Part 211 and ICH Q10 framework reviews. With two Phase 3 programs targeting initiation, process validation timelines and batch record alignment across global manufacturing sites will require early engagement.

IDEAYA has also indicated that evaluation of a potential first-line ES-SCLC Phase 3 study design is ongoing, with combination data still being generated, extending the manufacturing planning horizon further.

The first efficacy and safety readout from IDEAYA's global IDE849 monotherapy study, including post-Imdelltra SCLC and relapsed NEC cohorts, will serve as the next measurable checkpoint for both clinical and operational planning teams.

Source: IDEAYA Biosciences newsroom via PR Newswire, October 23, 2026.