A Study to Investigate the Safety and Tolerability of Intravenous QEQ278 in Patients With Advanced Solid Tumors

Inclusion Criteria: * Signed informed consent must be obtained prior to participation in the study. * Adult men and women ≥ 18 years of age. * Histologically confirmed and documented advanced malignancies (locally advanced malignancies, non-curable by surgery or radiotherapy and metastatic disease). Disease must be measurable, including presence of at least one measurable lesion, as determined by RECIST v1.1. * In the opinion of the treating investigator, patients must have received, but are not benefitting from standard therapies, be intolerant or ineligible to receive such therapy, or have no standard therapy option for the respective disease types (diseases listed below), as well as any other therapies deemed to be standard by local/institutional standard. * Non-small cell lung cancer * Esophageal squamous cell carcinoma * Renal cell carcinoma * HPV-associated head and neck squamous cell carcinoma * Must have a site of disease amenable to biopsy and be a candidate for tumor biopsy according to the treating institution's guidelines. The patient must be willing to undergo a new tumor biopsy at screening and during treatment. Exclusion Criteria: * Active previously documented or suspected autoimmune disease. Patients with vitiligo, type I diabetes, residual hypothyroidism only requiring hormone replacement, psoriasis not requiring systemic treatment, or conditions not expected to recur should not be excluded. Patients previously exposed to anti-PD-1/PD-L1 treatment who are adequately treated for skin rash or with replacement therapy for endocrinopathies should not be excluded. * Patients with a history of or current interstitial lung disease or pneumonitis ≥ Grade 2. * Patients who discontinued prior anti-PD-1 therapy due to an anti-PD-1-related toxicity * Clinically significant cardiac disease or risk factors at screening * Insufficient bone marrow function at screening: * Infections: * Known history of testing positive for Human Immunodeficiency Virus infection. * Active Hepatitis B and / or Hepatitis C. * Active, documented COVID-19 infection * Known history of tuberculosis * Any serious uncontrolled infection (acute or chronic). * Systemic chronic steroid therapy (\>10 mg/day prednisone or equivalent) or any immunosuppressive therapy, other than replacement-dose steroids in the setting of adrenal insufficiency, within 7 days of the first dose of study treatment. Topical, inhaled, and ophthalmic steroids are allowed. Other protocol-defined inclusion/exclusion criteria may apply.