Study of EOS-448 With Standard of Care and/or Investigational Therapies in Participants With Advanced Solid Tumors

Inclusion Criteria: * Provide a signed written informed consent for the trial * Have measurable disease, per RECIST v1.1 * Have an Eastern Cooperative Oncology Group (ECOG) performance status of Grade 0 or 1. * Have adequate organ functions * Part 1A/1B/1C/1D/1E/1F: Have histologically or cytologically confirmed advanced or metastatic solid tumor for whom no standard treatment with survival benefit is available Part 1G (NSCLC): * Have a histologically confirmed or cytologically confirmed previously untreated stage IV OR stage III not amenable to curative chemoradiotherapy or surgery (AJCC 8th edition) nonsquamous NSCLC OR squamous NSCLC. * Are eligible to receive anti-PD(L)1 therapy combined with chemotherapy in first line metastatic setting Part 2 (H\&N cancer) * Have histologically or cytologically confirmed recurrent advanced or metastatic head and neck squamous cell carcinoma considered incurable by local therapies * PD-L1 status positive Exclusion Criteria: * Have received any anti-cancer therapy within 4 weeks prior to the first dose * Have received a live vaccine within 30 days prior to the first dose * Have known primary CNS cancer. * Have known CNS metastases unless previously treated and well controlled for at least 1 month * Have concomitant second malignancies unless a complete remission was achieved at least 2 years before study entry * Have a history of Grade ≥ 2 pneumonitis, active autoimmune disease, or persistent immune-mediated toxicity caused by immune checkpoint inhibitor therapy of Grade ≥ 2 * Have toxicity (except for alopecia) related to prior anti-cancer therapy and/or surgery unless the toxicity is either resolved, returned to baseline or Grade 1, or deemed irreversible. * Have uncontrolled or significant cardiovascular disease * Part 1: major surgery within 3 weeks before initiating treatment * Part 1: Have received prior radiotherapy within 2 weeks of start of study treatment * Part 2 (H\&N cancer): * Have received prior immunotherapy with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibody (including ipilimumab or any other antibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways). * Have received prior chemotherapy administered in the recurrent advanced or metastatic setting (except for systemic therapy completed \> 6 months prior to screening if given as part of multimodal treatment for locally advanced disease)