FY2022 Q3 Financial and R&D Update

Best Percent Change in SOD From Baseline by BICR (n=40).% Progression-free survival, % 100 80 60 Dato-DXd 40 20 -------- 0 -20 -40 -80 -80 * Prior Topo I inhibitor-based ADC -100 100- 80- 60- 40- 20- TROPION-PanTumor01 Study SABCS 2022, TNBC Cohort Efficacy Antitumor Responses by BICR (n=40) aPostbaseline tumor assessments were not available for 1 patient at data cutoff. Three patients were not confirmed to have a target lesion per BICR and therefore had a best overall response of non-CR/non-PD. PFS (All Patients) 29/44 (66) Median (95% CI), mo Events n/N (%) 0- All patients 4.4 (3.0-7.3) T T T T 0 3 6 9 12 15 18 21 Time, months Data cutoff: July 22, 2022 Progression-free survival, % 100- 80- 60- 40° 20- PFS (Topo I Inhibitor-Naïve Patients) Median (95% CI), mo Events n/N (%) 0- Topo I inhibitor-naive patients 7.3 (3.0-18.0) 16/30 (53) T T T T 0 3 6 9 12 15 18 21 Time, months TROPION-Pan Tumor01 TNBC Cohort Daiichi-Sankyo Cohort of patients with unresectable or metastatic TNBC (including HER2 low) in Ph1 trial to evaluate safety and efficacy of Dato-DXd. Patients in this cohort. received a median of three lines of treatment for metastatic disease previously. ORR was 32% in all patients (n=44) and 44% in Topo I inhibitor-naïve patients (n=27) with measurable disease; mDOR was 16.8 months in both groups ■mPFS was 4.4 months in all patients and 7.3 months in Topo I inhibitor-naïve patients mOS was 13.5 months in all patients and 14.3 months in Topo I inhibitor-naïve patients ■No cases of ILD, febrile neutropenia, or grade ≥3 diarrhea were reported Results demonstrate encouraging efficacy and manageable safety profile in TNBC and support ongoing TROPION-Breast02 study BICR: blinded independent central review, CI: confidence interval, ILD: interstitial lung disease, mDOR: median duration of response, mOS: median overall survival, mPFS: median progression-free survival, ORR: objective response rate, PFS: progression-free survival, SABCS: San Antonio Breast Cancer Symposium, TNBC: triple-negative breast cancer 24

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