This is a Phase 1a/1b, open-label, dose escalation and expansion study to evaluate the safety and anti-tumor activity of DAY301, a PTK7-directed antibody-drug conjugate in patients with advanced or metastatic solid tumors. The study comprises of 2 phases: Phase 1a dose escalation where patients will be administered DAY301 at escalating dose levels to assess safety and tolerability, and to determine the maximum tolerated dose (MTD) and/or the recommended dose (RD); In Phase 1b dose expansion, DAY301 will be evaluated in dose expansion cohorts.
Inclusion Criteria:
* Patients with histologically or cytologically confirmed diagnosis of advanced or metastatic solid tumors of the following histologies:
* Ovarian cancer
* Esophageal squamous cell carcinoma
* Triple-negative breast cancer
* Non-small cell lung cancer
* Small cell lung cancer
* Head and neck squamous cell carcinoma
* Gastric/gastroesophageal junction adenocarcinoma
* Cervical squamous cell carcinoma
* Endometrial cancers
(Patients must have been previously treated with standard of care systemic therapy, or for whom no standard therapy is available).
* Availability of tumor tissue sample (either an archival specimen or a fresh biopsy) at screening
* Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST v1.1).
* ECOG performance status of 0 or 1.
* Adequate organ function.
Exclusion Criteria:
* Prior use of PTK7 targeting treatment.
* Active or progressing brain metastases or evidence of leptomeningeal disease.
* Persistent toxicities from previous systemic antineoplastic treatments of Grade \>1, excluding alopecia and vitiligo.
* Systemic antineoplastic therapy within 5 half-lives or 4 weeks, whichever is shorter, prior to first dose of the study drug, including investigational agents.
Note: Other protocol defined Inclusion/Exclusion criteria may apply.
