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

Inclusion Criteria:

1. Provide a signed written informed consent for the trial
2. Have measurable disease, per RECIST v1.1
3. Have an Eastern Cooperative Oncology Group (ECOG) performance status of Grade 0 or 1.
4. Have adequate organ functions
5. 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):

1. 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.
2. Are eligible to receive anti-PD(L)1 therapy combined with chemotherapy in first line metastatic setting

Part 2 (H&N cancer)

1. Have histologically or cytologically confirmed recurrent advanced or metastatic head and neck squamous cell carcinoma considered incurable by local therapies
2. PD-L1 status positive

Exclusion Criteria:

1. Have received any anti-cancer therapy within 4 weeks prior to the first dose
2. Have received a live vaccine within 30 days prior to the first dose
3. Have known primary CNS cancer.
4. Have known CNS metastases unless previously treated and well controlled for at least 1 month
5. Have concomitant second malignancies unless a complete remission was achieved at least 2 years before study entry
6. Have a history of Grade ≥ 2 pneumonitis, active autoimmune disease, or persistent immune-mediated toxicity caused by immune checkpoint inhibitor therapy of Grade ≥ 2
7. 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.
8. Have uncontrolled or significant cardiovascular disease
9. Part 1: major surgery within 3 weeks before initiating treatment
10. Part 1: Have received prior radiotherapy within 2 weeks of start of study treatment
11. Part 2 (H&N cancer):
12. 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).
13. 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)