• Measurable disease by RECIST 1.1 criteria.
• Adequate bone marrow or organ function.
• Life expectancy of ≥ 3 months.
• Sufficient performance status.
• Confirmed NSCLC, without small cell lung cancer transformation with or without brain metastases.

• Disease progression following or intolerance of standard of care (excluding patients in the treatment-naïve non-classical driver cohort):

  • Cohort 1 (Non-Classical driver cohort): Advanced/metastatic NSCLC with a non-classical driver EGFR mutation (eg, G719X) following up to 2 lines of therapy with only 1 prior EGFR TKI regimen (third-generation preferred; other approved EGFR TKI acceptable).
  • Cohort 2 (Acquired resistance C797S cohort): Advanced/metastatic NSCLC with the acquired resistance C797S EGFR mutation following up to 2 lines of therapy, including only one EGFR TKI, which must be a third generation EGFR TKI (eg, osimertinib).
  • Cohort 3 (First-line non-classical driver cohort): Treatment-naïve advanced/metastatic NSCLC with a non-classical driver EGFR mutation (1 cycle of chemotherapy or immune checkpoint inhibitor are permitted). Patients with co-occurring L858R mutations and a non-classical mutation are eligible for inclusion.

• Identification of one (or more) of the following EGFR mutations by Next Generation Sequencing (NGS) as determined by a local assay performed in a validated laboratory in the absence of other known resistance mutations (eg, T790M, MET):

  • Non-classical driver EGFR mutations (eg, L861R, S768I, G719X).
  • EGFR acquired resistance mutation (eg, C797S) to a 3rd generation EGFR TKI.
  • For Phase 2, dose expansion, patients in Cohort 1 who received 3rd generation EGFR TKI (eg, osimertinib), the NGS report within 6 months prior to the start of Screening is acceptable. For patients in Cohort 2, the NGS report must be from the last disease progression on the immediate prior therapy. For patients in Cohort 3, the NGS report must be at the time of diagnosis.
• No known resistant mutations in tumor tissue or by liquid biopsy (eg T790m, MET)
• No more than one line of EGFR TKI tx
• No symptomatic CBS dz

• Histologically or cytologically documented extensive-stage small cell lung cancer (ES-SCLC)
• Has received prior therapy with only one prior platinum-based line as systemic therapy for SCLC with at least 2 cycles of therapy and a chemotherapy free-interval of at least 30 days
• Measurable disease
• ECOG PS 0-1
• No brain or leptomeningeal disease
• No clinically significant corneal disease
• Cannot have received any of the comparators in the study or any topo-1 inhibitors

• ECOG PS 0-1
• Subjects who relapsed, progressed, or were intolerant to standard therapy, have a disease for which no therapy with a known overall survival benefit exists or are not a candidate for these therapies, and have one of the following cancers:

i. Histologically confirmed locally advanced/metastatic HER2-negative breast cancer, with deleterious or suspected deleterious BRCA1/2 mutation, that progressed on, was intolerant to, was refused, or ineligible for (PARPi).

ii. Histologically confirmed locally advanced/metastatic HGSOC (high-grade serous ovarian cancer), including primary peritoneal cancer (PPC) and fallopian tube cancer (FTC), that progressed on, was intolerant to, refused, or ineligible to maintenance treatment with a PARPi.

iii. Histologically confirmed locally advanced/metastatic CRPC, with deleterious or suspected deleterious BRCA1/2 mutation, that progressed on, was intolerant to, refused, or ineligible for PARPi.

iv. Histologically confirmed locally advanced/metastatic pancreatic cancer with deleterious or suspected deleterious BRCA1/2 mutation that progressed on, was intolerant to, refused, or ineligible for maintenance treatment with a PARPi.

v. Locally advanced/metastatic tumors with deleterious or suspected deleterious germline or somatic HRR mutation or HRD phenotype.

Cohort-Expansion Stage Single Agent and Combination:

b) HER2-negative BRCAm Breast cancer cohort: i. Histologically confirmed locally advanced/metastatic HER2-negative Breast cancer with deleterious or suspected deleterious BRCA1/2 mutation have documented radiographic disease progression during or following their last systemic anticancer therapy and that progressed on, was intolerant to, refused, or ineligible for treatment with a PARPi.

c) Platinum-resistant HGSOC cohort: i. Histologically confirmed locally advanced/metastatic HGSOC, including primary peritoneal cancer (PPC) and fallopian tube cancer (FTC), that progressed on, was intolerant to, refused, or ineligible to maintenance treatment with a PARPi and who have platinum-resistant disease, defined by platinum free interval of less than 6 months ii. Platinum-refractory disease (progression on first-line treatment or within 4 weeks of completion) are excluded.

d) Platinum-sensitive HGSOC cohort - expansion combination only: i. Histologically confirmed locally advanced/metastatic HGSOC, including PPC and FTC, that progressed on, refused, or ineligible to maintenance treatment with a PARPi, and who have platinum-sensitive disease, defined by platinum free interval of more than 6 months e) mCRPC cohort: i. Subjects with metastatic, castration-resistant adenocarcinoma of the prostate with deleterious or suspected deleterious BRCA1/2 mutation, that progressed on, or was intolerant, refused, or ineligible to PARPi.

f) HRRm advanced solid tumors cohort: i. Locally advanced/metastatic tumors with deleterious or suspected deleterious germline or somatic HRR mutation or HRD phenotype.

• No known symtomatic brain mets

• Participants must meet all of the following criteria to be eligible for enrollment into the trial:

• Adults ≥18 years of age on the day of signing the ICF.
• Participants must have at least 1 lesion, not previously irradiated, amenable to biopsy, and must consent to provide a pre-treatment biopsy from a primary and/or metastatic lesion.
• Has at least 1 measurable lesion according to RECIST version 1.1 per investigator assessment.
• Participants must have progressed radiologically on or after their most recent line of systemic therapy.
• Eastern Cooperative Oncology Group performance status of 0 or 1.

• Additional inclusion criteria for endometrial cancer cohort

  1. Pathologically or cytologically documented endometrial cancer (carcinoma of any histological subtype or carcinosarcoma), irrespective of MSI or mismatch repair status.
  2. Documented disease progression after having received ≥1 line of therapy (no more than 3), including PBC-containing systemic treatment and an anti-PD-1 therapy containing regimen (combined or sequential) in the advanced/metastatic setting.

• Additional inclusion criteria for cervical cancer cohort

  1. Pathologically or cytologically documented recurrent or persistent squamous, adenosquamous, or adenocarcinoma of the uterine cervix.
  2. Disease progression after having received ≥1 prior line of therapy that includes systemic therapy in the advanced or metastatic setting.

• Additional inclusion criterion for non-HGSOC cohort

  a. Pathologically or cytologically documented unresectable or metastatic CCOC, low grade endometrioid, low-grade serous, or mucinous OVC that was previously treated with at least 1 prior line of therapy.

• Additional inclusion criteria for urothelial cancer cohort

  1. Pathologically or cytologically documented unresectable or metastatic urothelial carcinoma of the bladder, renal pelvis, ureter, or urethra. Histological variants are allowed if urothelial histology is predominant.
  2. Relapsed or progressed after treatment with ≥1 prior line of therapy (maximum of 3) that contains anti-PD-(L)1 therapy in the perioperative or metastatic setting.
• Additional inclusion criterion for the ccRCC cohort a. Pathologically or cytologically documented unresectable or metastatic ccRCC that was previously treated with no more than 3 prior systemic regimens for locally advanced or metastatic RCC, including both a PD-(L)1 checkpoint inhibitor and a VEGF-TKI in sequence or in combination.

• Participants who meet any of the following criteria will be disqualified from entering the trial:

• Clinically active brain metastases, spinal cord compression, or leptomeningeal carcinomatosis
• Any of the following within the past 6 months prior to enrollment: cerebrovascular accident, transient ischemic attack, or other arterial thromboembolic event.
• Uncontrolled or significant cardiovascular disease as specified in the protocol.
• Has a history of (noninfectious) ILD/pneumonitis that required corticosteroids, has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening.
• Clinically severe pulmonary compromise
• Chronic steroid treatment (>10 mg/day) with exceptions as noted in the protocol.
• History of other active malignancy within 3 years prior to enrollment, with the exception of those with a negligible risk of metastasis or death (eg, 5-year OS rate >90%) and treated with expected curative outcome.
• Unresolved toxicities from previous anticancer therapy, defined as toxicities (other than alopecia) not yet resolved to NCI-CTCAE Version 5.0, Grade ≤1 or baseline.
• Prior exposure to other CDH6-targeted agents or an ADC that consists of an exatecan derivative that is a topoisomerase I inhibitor (eg, trastuzumab deruxtecan, datopotamab deruxtecan).
• Evidence of ongoing uncontrolled systemic bacterial, fungal, or viral infection.
• Has active or uncontrolled HIV, HBV, or HCV infection.