A Dose Escalation Study Of PF-06801591 In Melanoma, Head And Neck Cancer (SCCHN), Ovarian, Sarcoma, Non-Small Cell Lung Cancer, Urothelial Carcinoma or Other Solid Tumors

Inclusion Criteria (Part 2 Only): * Histological or cytological diagnosis of locally advanced or metastatic NSCLC or urothelial carcinoma who have progressed on or were intolerant to standard of care systemic therapy, or for whom standard of care systemic therapy was refused (refusal must be documented) or unavailable. * No prior treatment with anti-PD-1 or anti-PD-L1 therapy. * NSCLC patients whose tumor is not known to have ALK or EGFR mutations must have progressed on or after no more than 1 prior line of platinum-containing systemic therapy or were intolerant or refused standard of care systemic therapy. * NSCLC patients whose tumor is known to have ALK or EGFR mutation must have received prior systemic therapies that only include 1 or more lines of ALK or EGFR targeting drugs and chemotherapy limited to 1 line of a platinum-based regimen and they must have progressed on or after both types of therapies. * Urothelial carcinoma patients must have received up to 2 lines of prior systemic therapy and progressed on or after, experienced disease recurrence within 12 months of neoadjuvant or adjuvant treatment, were intolerant to, ineligible or refused platinum-containing systemic therapy. If urothelial cancer patients are treatment naïve and eligible for platinum-containing systemic therapy but are refusing platinum chemotherapy, they must also be documented to have previous PD-L1 high status. * Provide archived tumor tissue sample taken within the past 2 years or provide a fresh tumor biopsy sample. * At least one measurable lesion as defined by RECIST version 1.1. * Adequate renal, liver, thyroid and bone marrow function. * Performance status 0 or 1. * Patient is capable of receiving study treatment for at least 8 weeks. Exclusion Criteria (Part 2 Only) * Active brain or leptomeningeal metastases. * Active, known or suspected autoimmune disease. Patients with vitiligo, type I diabetes mellitus, residual hypothyroidism due to autoimmune condition only requiring hormone replacement, psoriasis not requiring systemic treatment, or conditions not expected to recur in the absence of an external trigger are permitted to enroll. Diagnosis of prior immunodeficiency or organ transplant requiring immunosuppressive therapy or prior allogeneic bone marrow or hematopoietic stem cell transplant. * Patients with a condition requiring systemic treatment with either corticosteroids (\>10mg daily prednisone equivalents) or other immunosuppressive medications within 14 days of study drug administration. Inhaled or topical steroids, and adrenal replacement doses \>10 mg daily prednisone equivalents are permitted in the absence of active autoimmune disease. * Patients with a history of interstitial lung disease, non-infectious pneumonitis, or active pulmonary tuberculosis. Those with active lung infections requiring treatment are also excluded. * History of Grade ≥3 immune mediated AE (including AST/ALT elevations that where considered drug related and cytokine release syndrome) that was considered related to prior immune modulatory therapy (eg, immune checkpoint inhibitors, co-stimulatory agents, etc.) and required immunosuppressive therapy. * Active hepatitis B or C, HIV/AIDS. * Other potentially metastatic malignancy within past 5 years.