First-in-Human Study of DS-3939a in Participants With Advanced Solid Tumors

Has had prior treatment targeting mucin 1 (MUC1) or TA-MUC1.

Has spinal cord compression or clinically active central nervous system metastases.

Has multiple primary malignancies, except adequately resected non-melanoma skin cancer, curatively treated in situ disease, or other solid tumors curatively treated, with no evidence of disease for ≥3 years.

Has a history of noninfectious interstitial lung disease (ILD)/pneumonitis (including suspected one), has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at Screening.