Investor Presentaiton

HER3-DXd NSCLC Ph1 study cohort 2 data ASCO 2022 Highlights Daiichi-Sankyo The promising clinical activity of HER3-DXd in patients with NSCLC harboring a broad range of genomic alterations or without genomic alterations Anti-tumor activity (With (A) or Without (B) genomic alterations) (A) (B) Best percentage change in sum of diameters -40 -80 2202488 -20 CR PR BOR by BICR SD PD NE + Treatment ongoing Outcomes (BICR per RECIST 1.1) Confirmed ORR (95% CI), % -60 Disease control rate (95% CI), % N=21 28.6 (11.3, 52.2) 76.2 (52.8, 91.8) Time to response, median (range), mo Duration of response, median (95% CI), mo PFS, median (95% CI), mo 2.8 (1.3-4.6) 9.4 (4 2-NE) 10.8 (2.8-16.0) -100 EGFR Driver genomic ERBB2 alteration AMP MET EGFR KRAS EGFR ERBB2 AMP Ex20ins G12C Ex20ins D769Y EGFR CD74: Ex20ins ROS1 KRAS CD74: G12D ROS1 EGFR Ex20ins T751 1759 delinsN EGFR KRAS L861R G12C ERBB2 A775_6776 inSYVMA RET fusion NRAS EML4 Q61L ALK KRAS EML4 G12F ALK ALK On-target resistance mechanism Off-target resistance mechanism ROS1 D2033N ROS1 G2032R ALK L1196M G1202R $1206F S1206Y BRAF V600E Best percentage change in sum of diameters CR PR BOR by BICR SD PD NE + Treatment ongoing 40 20 0 -20 -40 Outcomes (BICR per RECIST 1.1) N=26 -60 Confirmed ORR (95% CI), % Disease control rate (95% CI), % 26.9 (11.6, 47.8) 73.1 (52.2, 88.4) Time to response, median (range), mo -80 9.6 (1.6-NE) 4.2 (2.5-10.8) -100 + Cohort 2 Patients with advanced NSCLC without common EGFR mutations ■HER3-DXd showed promising clinical activity and manageable safety profile in patients with or without genomic alterations Presented cohort 1 data with EGFR mutations at last year's ASCO Duration of response, median (95% CI), mo PFS, median (95% CI), mo 2.1 (1.2-6.0) Data cutoff: January 28, 2022. Twenty of 21 patients with identified driver mutations, and 24 of 26 patients without, had best percentage change in sum of diameters data available. BICR: blinded independent central review, BOR: best objective response, NSCLC: non small cell lung cancer 27

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