Daiichi Sankyo (4568) investor relations material

Disease landscape and unmet need

• Extensive-stage small cell lung cancer (ES-SCLC) has a high unmet medical need, with poor five-year survival rates (as low as 9%) and frequent brain metastases, leading to poor prognosis.

• SCLC accounts for 13.8% of lung cancers, with most patients presenting with extensive-stage disease and limited efficacy from standard second-line therapies (median OS 6.0-9.3 months).

• Recent drug approvals, including immunotherapies and tarlatamab, have modestly improved options, but significant unmet needs remain.

Program overview and clinical data

• IEDxB/I-DXd is a B7-H3-directed ADC using DXd technology, sharing linker and payload with Enhertu, and demonstrates broad anti-tumor activity across multiple solid tumors.

• In phase 2 (IDeate-Lung01), 137 ES-SCLC patients treated with 12 mg/kg had a confirmed ORR of 48.2%, median DOR 5.3 months, median PFS 4.9 months, and median OS 10.3 months.

• Efficacy was consistent across subgroups, including those with brain metastases, platinum-resistant disease, and prior therapies, with rapid and durable responses (median TTR 1.4 months).

• Phase 1 trials showed robust efficacy in heavily pretreated populations, leading to phase 3 trials in prostate, esophageal, and vaginal cancers.

Safety profile

• IEDxB/I-DXd at 12 mg/kg was generally well tolerated, with most common TRAEs being hematologic or GI; adjudicated ILD/pneumonitis occurred in 12.4-12.7% of patients.

• Grade ≥3 TRAEs occurred in 36.5% of patients, with 4.4% associated with death; safety profile is distinct from competitors, notably lacking cytokine release syndrome.