Daiichi Sankyo Company (4568) Status Update summary

Key clinical trial highlights

• DESTINY-Breast06 showed trastuzumab deruxtecan (T-DXd/Enhertu) significantly improved progression-free survival (PFS) over chemotherapy in HR+, HER2-low and HER2-ultralow metastatic breast cancer, with median PFS of 13.2 vs 8.1 months and a median PFS difference of 5 months, and consistent efficacy across subgroups.

• Confirmed objective response rate (ORR) was 57.3% for T-DXd vs 31.2% for chemotherapy in the intent-to-treat population.

• DESTINY-Breast03 updated results confirmed T-DXd's superiority over T-DM1 in second-line HER2-positive metastatic breast cancer, with a median overall survival of 52.6 months and a manageable safety profile.

• DESTINY-Breast07 interim data in first-line HER2-positive metastatic breast cancer showed robust and durable response rates for T-DXd alone and in combination with pertuzumab, with ORR of 76.0% and 84.0%, and 12-month PFS rates of 80.8% and 89.4%, supporting ongoing phase 3 trials.

• DESTINY-Lung02 final analysis in HER2-mutant non-small cell lung cancer confirmed robust efficacy for T-DXd at both 5.4 and 6.4 mg/kg, with the lower dose favored for safety and median OS of 19.0 months.

• TROPION-Lung02 demonstrated encouraging response rates and durability for datopotamab deruxtecan plus pembrolizumab (with/without chemotherapy) in first-line advanced non-small cell lung cancer, with manageable safety and ongoing pivotal trials.

Strategic and scientific insights

• The DXd ADC platform is being advanced across multiple assets and tumor types, with a focus on addressing unmet needs in oncology.

• DESTINY-Breast06 results may reclassify breast cancer patients and expand treatment to a broader population, including those with ultra-low HER2 expression, potentially benefiting ~85% of HR+, HER2-negative mBC patients.

• Diagnostic strategies for HER2-ultralow are evolving, with ongoing education for pathologists and continued reliance on immunohistochemistry testing.

• Competitive positioning in TROP2 ADCs is supported by operational speed, a robust clinical program, and biomarker development.

• Mechanistic rationale for efficacy in HER2-ultralow includes the bystander effect of the DXd payload, with ongoing exploration in other tumor types.

Regulatory and market outlook

• DESTINY-Breast06's strong PFS and ORR data may support regulatory approval, even if overall survival is not yet statistically significant, following precedent from earlier trials.

• Safety profiles for T-DXd and Dato-DXd remain consistent with prior studies, with no new safety signals, though interstitial lung disease remains a key risk; incidence was 11.3% in DESTINY-Breast06 and 14.9% in DESTINY-Lung02 (5.4 mg/kg arm).

• Market uptake for Enhertu in new indications is expected to be significant if approved, given the favorable benefit-risk profile and unmet need.

• Ongoing and future studies aim to further expand indications, including studies in HER2-zero populations, earlier lines of therapy, and further subgroup and biomarker analyses.

• Phase 3 DESTINY-Breast09 is evaluating T-DXd regimens versus standard THP in first-line HER2+ mBC.