This is a first-in-human study of KK2269. Part 1 and Part 2 will be conducted as a multicenter, open-label, non-randomized, dose-escalation study. Participants with advanced or metastatic solid tumors for which no standard therapy is available will be enrolled in Part 1. In Part 1, the primary objective is to assess the safety and tolerability of KK2269.

In Part 2, only participants with gastric adenocarcinoma, GEJ adenocarcinoma, esophageal adenocarcinoma, or NSCLC who have experienced at least one systemic therapy will be enrolled. In Part 2, the primary objective is to assess the safety and tolerability of KK2269 in combination with docetaxel and to determine the recommended dose(s) and dose interval(s) of KK2269 in combination with docetaxel for subsequent studies.

In both Part 1 and Part 2, participants who refuse to undergo standard therapy are also eligible.

• Key Common Inclusion Criteria for Parts 1 and 2:

  • Patients who are ≥ 18 years old at the time of informed consent
  • Patients who have disease measurable by RECIST v1.1
  • Patients with an ECOG PS of 0 or 1
  • Patients with a life expectancy of at least 3 months in the judgement of the investigator or subinvestigator
  • The specified periods have passed respectively after the completion of previous cancer treatments as of the date of enrollment at the time of the first dose of KK2269
  • Patients who agree to use a medically effective method of contraception

• Key Additional Inclusion Criterion for Part 1:

  •Patients with histological or cytological evidence of at least one locally advanced or metastatic non-CNS solid tumor

• Key Additional Inclusion Criteria for Part 2:

  •Patients with histological or cytological evidence of any of the following disease: Gastric adenocarcinoma, GEJ adenocarcinoma, or esophageal adenocarcinoma, NSCLC (Only patients with NSCLC will be enrolled in the expansion part)

  •Patients who are suitable for docetaxel treatment

• Key Common Exclusion Criteria for Parts 1 and 2:

  • Patients with an uncontrolled or serious intercurrent illness
  • Patients with known active central nervous system metastasis
  • Patients with a history of ≥ Grade 3 allergic reaction to any antibody drug
  • Patients with a history of autoimmune disease
  • Patients with a history of HIV, HBV, or HCV at screening
  • Patients who have a history of primary immunodeficiency

• Key Additional Exclusion Criterion For Part 2:

  • Patients with a history of treatment with docetaxel

The datasets generated and/or analyzed during the study sponsored by Kyowa Kirin will be available in the Vivli repository, https://vivli.org/ourmember/kyowa-kirin/ as long as conditions of data disclosure specified in the policy section of the Vivli website are satisfied.