A Phase 1, 2-Part, Multicenter, Open-Label, First-in-Human Study of the Anti-Ly6E Exatecan Antibody-Drug Conjugate M7437 in Participants With Advanced Solid Tumors

Inclusion Criteria: * Participants have histologically proven advanced solid tumors with known prevalent and high Ly6E expression, Disease characteristic: Participants should have an unresectable locally advanced or metastatic solid tumor that is refractory to standard therapies, or have no standard therapies, or for which no standard therapy is judged appropriate by the Investigator. For each tumor type, participants have received prior lines of therapy, where locally available: * Non-small cell lung cancer (nonsquamous or squamous) * Triple-negative breast cancer * Squamous cell carcinoma of head and neck * Pancreatic ductal adenocarcinoma * Gastric cancer * Epithelial ovarian cancer * Participants with ECOG Performance Status (ECOG) less than and equal to (\<=) 1 * Participants must have blood, liver, and kidney function within safe levels. * Other protocol defined inclusion criteria may apply Exclusion Criteria: * Participant has a history of another malignancy within 3 years before the date of enrollment (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix, benign prostate neoplasm/hyperplasia, or malignancy that in the opinion of the Investigator, with concurrence with the Sponsor's Medical Monitor, is considered cured with minimal risk of recurrence within 3 years before the date of enrollment). History of hematopoietic allogenic transplantation. * Participants with known brain metastases, except those meeting both of the following criteria: 1. All brain metastases have been treated locally and are clinically stable for at least 4 weeks prior to the start of treatment. 2. No ongoing neurological symptoms that are related to the brain localization of the disease (sequelae that are a consequence of the treatment of the brain metastases are acceptable). * Participants with diarrhea (liquid stool) or ileus Grade more than (\>) 1 within 1 week of Cycle1Day1. * Participants with active chronic inflammatory bowel disease and/or bowel obstruction. * Participants with history of serious gastrointestinal bleeding within 3 months of Cycle1Day1. * Other protocol defined exclusion criteria may apply.