Fourth Quarter & Full Year 2022 Financial & Business Update

Novel SGN-B7H4V has Potential Utility in Breast, Endometrial and Ovarian Cancer, with Full Global Rights and Initial Data 2H 2023 SGN-B7H4V Novel, vedotin ADC targeting B7-H4, an immune checkpoint that is upregulated in many solid tumors ⚫ B7-H4 expression is low on normal tissue and immune cells, in contrast to certain other members of the B7 family (e.g., B7-H3) Seagen Adapted from Poster No. 854 presented at SITC 2021 B7-H4 is Expression by Tumor Type 1 2 3 Ovarian (high grade serous, n = 63)- Breast (n =151)- Endometrial adenocarcinoma (n = 274) TMA cores 0 20 40 60 80 100 % B7-H4+ (IHC intensity score 1-3, frequency >25% of tumor) 28

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