A Study Assessing KB707 for the Treatment of Locally Advanced or Metastatic Solid Tumors

Key Inclusion Criteria: * Life expectancy \>12 weeks * ECOG performance status of 0 or 1 * Have measurable disease per RECIST v1.1 at Screening * Cohorts 1-4 only: Histologically confirmed diagnosis of a locally advanced or metastatic solid tumor and the individual has progressed on standard of care therapy, cannot tolerate standard of care therapy, refused standard of care therapy, or there is no standard of care therapy. * Cohorts 5 and 6 only: Histologically confirmed stage III (unresectable) or stage IV melanoma, as per American Joint Committee on Cancer (AJCC) staging system (8th edition; AJCC 2017) and 1. Subject has previously failed one prior anti-PD-1/PD-L1 treatment (as monotherapy or in combination with other checkpoint inhibitors such as anti-LAG-3 or anti-CTLA-4); and 2. If proto-oncogene B-Raf (BRAF) V600 mutation-positive, subject previously failed a BRAF inhibitor or BRAF inhibitor in combination with mitogen-activated extracellular signal-regulated kinase (MEK) inhibitor * Cohort 5 only: Age 12 years or older at the time of informed consent * Cohort 6 only: Age 18 years or older at the time of informed consent Key Exclusion Criteria: * Prior surgery or radiation therapy must be fully recovered, including all radiation -related toxicities and subject does not require systemic corticosteroids * The subject is pregnant, nursing, or plans to become pregnant during study treatment and through three months after the last dose of KB707 * Have known history of positive human immunodeficiency virus (HIV 1/2) * Cohorts 5 and 6 only: 1. Subject has a known additional malignancy that is progressing or requires active treatment. 2. Subject has uveal/ocular melanoma. 3. The subject has active brain metastases or leptomeningeal metastases 4. Subject has received more than 2 lines of systemic therapy for unresectable or metastatic melanoma 5. Prior anti-LAG-3 and/or anti-PD-1 therapy was intolerable and required discontinuation of treatment