A Study of NPX887 for Participants With Solid Tumors Known to Express B7-H7/HHLA2

Inclusion Criteria:

• Histologically or cytologically confirmed recurrent, metastatic solid tumorrefractory to, or intolerant of, standard of care therapy in one of the followingindications:

• Phase 1a (Dose Escalation): Non-small cell lung carcinoma (NSCLC), small celllung carcinoma (SCLC), renal cell carcinoma (RCC), colorectal carcinoma (CRC),gastric and gastro-esophageal carcinoma, esophageal adenocarcinoma, biliarytract cancers, ovarian carcinoma, and other solid tumor types known to expressB7-H7/HHLA2.

• Phase 1b including Part 1b (Dose Expansion) and Part 1c (Randomized DoseComparison): participants who have clear cell RCC, EGFR mutant lungadenocarcinoma, or gastric/GEJ adenocarcinoma.

• In Phase 1b, participants must have confirmed B7-H7/HHLA2 expression in theirtumor determined via archival tissue IHC testing through a central lab (pre-screening).

• Phase 1a: Evaluable disease (measurable or non-measurable) by RECIST v.1.1 criteria;Phase 1b: Measurable disease by RECIST v1.1 criteria with additionaldisease-specific enrollment criteria applied to clear cell RCC, EGFR mutant lungadenocarcinoma, or gastric/GEJ adenocarcinoma.

• Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2.

• Ability to understand and the willingness to sign a written informed consentdocument

• Willing to use highly effective contraceptive measures throughout the trial.

Exclusion Criteria:

• Treatment with any of the following:

• Systemic anticancer treatment ≤14 days or within 5 half-lives prior to thefirst dose of study drug, whichever is shorter.

• Limited-field radiotherapy ≤7 days or extended-field thoracic radiotherapy ≤8weeks of the first dose of study drug.

• Have any unresolved toxicity of ≥Grade 2 from previous anti-cancer treatment, exceptfor alopecia, chronic stable neuropathy for >4 months, changes in skin pigmentation,or requiring replacement therapy for endocrine abnormalities.

• Participants with known brain metastases are excluded unless they are clinicallystable, with no new or enlarging brain metastases as evidenced on MRI duringscreening.

• History of Grade 3 immune-related pneumonitis or colitis.

• Participants who discontinued prior immunotherapy due to immune-related toxicities,or history of unresolved prior immune-related toxicity except for endocrineabnormalities requiring replacement therapy or vitiligo.

• Known autoimmune disease requiring immunosuppressive treatment requiring theequivalent of more than 10 mg prednisone daily.