T-regulatory Cell Depletion With E7777 Combined With Pembrolizumab in Recurrent or Metastatic Solid Tumors

Inclusion Criteria: * Ability to comply with the study protocol, in the investigator's judgment * Histologically or cytologically confirmed solid tumors (cutaneous melanoma, non-small cell lung cancer, renal cell carcinoma, endometrial cancer, ovarian cancer, MSI-H solid tumors (deficient mismatch repair system or other solid tumors) that have progressed on or refractory to standard of care therapies for their disease * Phase I dose escalation phase * Advanced metastatic or recurrent solid tumors (where pembrolizumab is approved and/or have shown efficacy) that have progressed on or refractory to standard of care therapies for their disease * Prior anti-PD1 or PDL1 therapy is allowed * Prior anti-CTLA4 therapy is allowed if had anti-CTLA4 free interval of 6 months or more * At least one prior line of therapy in the dose escalation phase * Phase Ib dose expansion cohorts * Platinum-resistant recurrent ovarian cancer (recurred within 6 months or less of prior platinum therapy) or post-PD1/PDL1 MSI-H cancers (mismatch repair deficient tumors). Patients in the ovarian cancer cohort must have received chemotherapy plus bevacizumab unless bevacizumab is contra-indicated or considered risky per treating physician. * Prior 1-5 lines of therapy for dose expansion * Prior anti-PD1/PDL1 therapy is allowed in the MSI-H cohort but not in the ovarian cohort * Prior anti-CTLA4 therapy is not allowed. * Primary platinum- refractory cancers are excluded in the dose expans…