The purpose of this study is to see how safe and effective ABBV-CLS-579 is when used alone and in combination with a PD-1 target agent or with a VEGF TKI.

ABBV-CLS-579 is an investigational drug being developed for the treatment of tumors.

The trial aims to establish a safe, tolerable, and efficacious dose of ABBV-CLS-579 as monotherapy and in combination. The study will be conducted in three parts. Part 1 Monotherapy Dose Escalation, Part 2 Combination Dose Escalation, and Part 3 Combination Dose Expansion.

Part 1, ABBV-CLS-579 will be administered alone in escalating dose levels to eligible subjects who have advanced solid tumors.

Part 2, ABBV-CLS-579 will be administered at escalating dose levels in combination with a PD-1 targeting agent to eligible subjects who have advanced solid tumors.

Part 3, ABBV-CLS-579 will be administered at the determined recommended dose in combination with a PD-1 target agent or with a VEGFR TKI in subjects with locally advanced or metastatic, relapsed or refractory head and neck squamous cell carcinoma (HNSCC), relapsed or refractory non-small cell lung cancer (NSCLC), and advanced clear cell renal cell carcinoma (ccRCC).

Adult participants with a diagnosis of some solid tumors for which no effective standard therapy exists or has failed will be enrolled. Participants will receive study treatment until disease progresses or discontinued.

There may be a higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the course of the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects, and completing questionnaires.

Inclusion Criteria:

• Must weigh at least 35 kilograms (kg).

• For Monotherapy and Combination Dose Escalation:

  • Histologically or cytologically proven metastatic or locally advanced tumors (with measurable disease defined by Response Evaluation Criteria In Solid Tumors [RECIST] v1.1), for which no effective standard therapy exists, or where standard therapy has failed. Participants must have received at least 1 prior systemic anticancer therapy for the indication being considered.

• For Combination Dose Expansion:

  • For the following tumor types, the subject must have received at least 1 prior line containing PD-1/PD-L1 target therapy.

Indication with outcome of Prior PD-1/PD-L1 Targeted Therapy and other disease characteristics:

• NSCLC

  • Relapsed: Tumors express PD-L1 (TPS ≥ 1%) as determined by the FDA-approved Agilent PD-L1 IHC 22C3 pharmDx kit
  • Refractory: Tumors express PD-L1 (TPS ≥ 1%) as determined by the FDA-approved Agilent PD-L1 IHC 22C3 pharmDx kit

• ccRCC

  • Relapsed or Refractory: Advanced disease (locally advanced or metastatic)

• MSI-H tumors

  • Refractory: Locally advanced or metastatic MSI-H tumors whose tumors are determined to have a MSI-H status by PCR or NGS tests, or dMMR by IHC tests.

• HNSCC

  • Relapsed or Refractory: Tumors express PD-L1 (CPS ≥ 1] as determined by the FDA approved PD-L1 Agilent IHC 22C3 pharmDx kit

• For Combination Dose Expansion:

  • Locally advanced or metastatic, advanced ccRCC who have relapsed after at least 1 prior VEGFR TKI therapy

• Received at least 1 prior line containing PD 1/PD L1 targeted therapy with a best response by RECIST v1.1 of CR/PR (any duration) or stable disease (for greater than 6 months)

• Received at least 1 prior line containing PD-1/PD-L1 targeted therapy and have had disease progression (in the absence of best response of CR/PR/stable disease by RECIST v1.1) with PD 1/PD L1 targeted therapy

• An Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2.

• Life expectancy of ≥ 12 weeks.

• Laboratory values meeting protocol criteria.

• If the subject is on anticoagulant therapy, INR must be within therapeutic goal.

• QT interval corrected for heart rate < 450 msec (using Fridericia's correction), and no clinically significant electrocardiographic findings.

Exclusion Criteria:

• Untreated brain or meningeal metastases (participants with history of metastases are eligible provide they do not require ongoing steroid treatment and have shown clinical and radiographic stability for at least 28 days after definitive therapy).

• Unresolved Grade 2 or higher toxicities related to previous anticancer therapy except alopecia.

• History of hepatitis B, hepatitis C, or human immunodeficiency virus (HIV) infection.

• Recent history (within 6 months) of congestive heart failure (defined as New York Heart Association, Class 2 or higher), ischemic cardiovascular event, pericarditis, or clinically significant pericardial effusion, cardiac arrythmia or peripheral artery disease.

• Recent history (within 6 months) of Childs-Pugh B or C classification of liver disease.

• History of clinically significant medical and/or psychiatric conditions or any other reason that, in the opinion of the investigator, would interfere with participation in this study or would make the participant an unsuitable candidate to receive study drug.

• History of uncontrolled, clinically significant endocrinopathy.

• Known gastrointestinal disorders making absorption of oral medications problematic. Inability to swallow capsules.

• If treated with anti-programmed cell death protein-1 (aPD-1)/antiprogrammed cell death protein-ligand 1(aPD-L1) targeting or other immunostimulatory agents in the past: excluded if had prior pneumonitis, prior Grade 3 or higher immune mediated toxicity, hypersensitivity to administered drug or drug related toxicity requiring discontinuation.

• Active autoimmune disease requiring systemic treatment in past 2-years (exceptions for endocrinopathies, vitiligo or atopic conditions)

• History of solid organ transplant or allogeneic stem cell transplant.

• History of interstitial lung disease or pneumonitis.

• Major surgery ≤ 28 days prior to first dose of study drug.

• Poorly controlled hypertension

• History of hemorrhage, including hemoptysis, hematemesis, or melena

• History of other malignancy, with the following exceptions:

  • No known active disease present for within 3 years before first dose of study treatment and felt to be at low recurrence by investigator
  • Adequately treated non-melanoma skin cancer or lentigo maligna without evidence of disease
  • Adequately treated carcinoma in situ without evidence of disease

• Known active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection per local testing practices.