A Study to Assess the Adverse Events, Change in Disease Activity, and How Oral ABBV-711 Tablets Move Through the Body as a Monotherapy and in Combination With Intravenously Infused Budigalimab (ABBV-181), in Adults With Advanced Squamous Tumors

Inclusion Criteria:

• Must have progressed on or after standard of care therapy and have no curativetherapy available (participants who have refused, are considered ineligible for orare intolerant to standard of care therapy are eligible).

• Received programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) targeted agents are eligible.

• Confirmation of available archival tumor tissue (formalin-fixed paraffin-embedded [FFPE] block or freshly cut slides) or provision of fresh tissue biopsy is requiredfor enrollment in this study for gene expression assessment. If archival tissuerequirements cannot be met then the AbbVie therapeutic area Medical Director ordesignee should be contacted to determine subject eligibility.

• For head and neck squamous cell carcinoma (HNSCC) participants enrolled in backfill (Part 1 and 3), subjects must provide consent to paired biopsies which arepretreatment and on treatment fresh tumor biopsies from the same tumor lesion,unless deemed not feasible by the investigator where upon consultation with theSponsor is required. Paired biopsies are encouraged (when safe and feasible) but notrequired for subjects with squamous non-small cell lung cancer (sqNSCLC) enrolled inthe backfill (Part 1 and 3).

• Evaluable and measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1.

Exclusion Criteria:

• Active autoimmune diseases besides vitiligo, type 1 diabetes, hypothyroidism,hypopituitarism and psoriasis (not requiring systemic treatment); history of primaryimmunodeficiency, bone marrow transplantation, or solid organ transplantation.Active inflammatory bowel disease unfit for trial in the opinion of theinvestigator, including subjects requiring systemic therapy with biologics orimmunosuppressive therapy within the past 2 years.

• Treatment with any of the following:

• Anti-cancer therapy including chemotherapy, radiation therapy, immunotherapy,biologic, or any investigational therapy within 28 days or 5 half-lives of thedrug (whichever is shorter) prior to the first dose of ABBV-711. Palliativeradiation therapy for bone, skin or symptomatic metastases with 10 fractions orless is not subject to a washout period.

• Radiation therapy for central nervous system metastases within 14 days prior tofirst dose.

• Subject has systemically used known moderate/strong inhibitors of cytochrome P450 3A (CYP)3A enzyme isoform subfamily within 14 days or 5 half-lives of the drug (whichever is shorter) prior to the first dose of study treatment.

• Has systemically used known moderate/strong inducers of CYP3A within 14 days priorto the first dose of study treatment.

• Requires treatment with known moderate or strong inhibitors or inducers of CYP3Afrom the first dose of study treatment and for the duration of the study.

• Administration or consumption of any of the following within 3 days prior to firstdose of study treatment and while on study treatment: grapefruit or grapefruitproducts, Seville oranges (including marmaladecontaining Seville oranges), and starfruit.

• Current or prior use of immunosuppressive medication within 14 days prior to thefirst dose of the study treatment. The following are exceptions to this criterion:

• Intranasal, inhaled, topical steroids or local steroid injections (e.g.,intra-articular injection);

• Steroids as premedication for hypersensitivity reactions (e.g., CT scanpremedication);

• Systemic corticosteroids at doses not to exceed 10 mg/day of prednisone orequivalent.