A Study of INCMGA00012 in Squamous Carcinoma of the Anal Canal Following Platinum-Based Chemotherapy (POD1UM-202)

Inclusion Criteria:

* Ability to comprehend and willingness to sign a written informed consent form.
* Confirmed diagnosis of locally advanced or metastatic SCAC.
* Must have received (or been intolerant to or ineligible for) at least 1 prior line of platinum-based chemotherapy and received no more than 2 prior systemic treatments.
* Must have measurable disease by RECIST v1.1.
* Eastern Cooperative Oncology Group performance status of 0 to 1.
* If HIV-positive, then all of the following criteria must also be met: CD4+ count ≥ 300/μL, undetectable viral load, and receiving highly active antiretroviral therapy.

Exclusion Criteria:

* Receipt of anticancer therapy or participation in another interventional clinical study within 21 days before the first administration of study drug; 6 weeks for mitomycin C.
* Radiotherapy within 14 days of first dose of study treatment with the following caveats: 28 days for pelvic radiotherapy, 6 months for thoracic region radiotherapy that is \> 30 Gy.
* Prior treatment with programmed cell death protein 1 (PD-1) or programmed cell death ligand protein 1 (PD-L1)-directed therapy.
* Active autoimmune disease requiring systemic immunosuppression.
* Known central nervous system (CNS) metastases and/or carcinomatous meningitis.
* Known active hepatitis infection.
* Active infections requiring systemic therapy.
* Is pregnant or breastfeeding or is expecting to conceive or father children within the projected duration of the study, from screening through 6 months after the last dose of study drug.