This is a phase I/Ib, first-in-human (FIH), open-label, dose escalation and dose expansion study to evaluate the safety and tolerability, biological and clinical activities of GEN-001 in patients with locally advanced or metastatic solid tumors who have progressed on at least two lines of approved therapy for their histological subtypes which includes an anti-PD-1 or anti-PD-L1 based therapy (as mono or combination), when administered as combined with avelumab.

Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Have adequate organ functions as defined in the protocol
• Negative childbearing potential
• Have ability to swallow and retain oral medication and no clinically significant gastrointestinal abnormalities
• Patients with diseases for which no curative therapies are available, and who have progressed on at least two lines of approved therapy for their histological subtypes which includes an anti-PD-1 or anti-PD-L1 based therapy (as mono or combination)
• Disease progression on anti-PD-(L)1 based therapy (as monotherapy or combination therapy) and must meet criteria for acquired resistance as defined in the protocol
• Patients who have completely recovered from any clinically significant AEs that occurred during prior immunotherapy
• Estimated life expectancy of at least 3 months
• Objective evidence of disease progression at baseline (Dose Escalation)
• Histologically or cytologically confirmed, unresectable, locally advanced, or metastatic NSCLC, SCCHN, and UC (Dose Expansion)
• Measurable disease as per RECIST v1.1 defined as at least 1 lesion (Dose Expansion)

Exclusion Criteria:

• Have experienced primary resistance to anti-PD-(L)1 based therapy
• Has experienced a toxicity that led to permanent discontinuation of prior anti-PD-(L)1 based therapy or other immunotherapies
• Has active autoimmune disease that has required systemic treatment in the past 2 years
• Current use of immunosuppressive medication at time of study entry
• Have an active infection requiring antibiotics, antifungal or antiviral agents or have received a course of antibiotics within the previous 4 weeks of starting study treatment
• Has received a live vaccine within 4 weeks of starting of study treatment
• Known history of, or any evidence of active, non-infectious pneumonitis
• Prior solid organ or allogeneic stem cell transplantation
• Has had any investigational or anti-tumor treatment within 4 weeks or 5 half-life periods of starting study treatment, had any major surgeries within 4 weeks of starting study treatment
• Has received proton pump inhibitors (PPIs) within 2 weeks prior to dosing study treatments
• Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis
• Has clinically significant (i.e., active) cardiovascular disease
• Has known history of uncontrolled intercurrent illness
• Has any psychiatric condition that would prohibit the understanding or rendering of informed consent or that would limit compliance with study requirements.