• Age ≥ 18 years
• Relapsed/metastatic solid tumors treated with prior adequate standard of care therapy for tumor type and stage of disease or where in the opinion of the Investigator, a clinical trial is the best option for the next treatment based on response and/or tolerability to prior therapy.
• Measurable disease per RECIST v1.1
• Eastern Cooperative Oncology Group (ECOG) Performance Status: 0-1
• Life expectancy ≥ 12 weeks
• Adequate organ and marrow function as defined in the protocol

• Treatment with any of the following:
  1. Nitrosourea or mitomycin C within 6 weeks prior to the first dose of study treatment
  2. Any investigational agents or study drugs from a previous clinical study within 5 half-lives or 28 days (whichever is shorter) prior to the first dose of study treatment
  3. Any other anticancer treatment within the following time periods prior to the first dose of study intervention:
     1. Cytotoxic treatment: 21 days
     2. Non-cytotoxic drugs: 21 days or 5 half-lives (whichever is shorter)
     3. Biological products including immuno-oncology agents: 28 days
• Spinal cord compression or a history of leptomeningeal carcinomatosis.
• Brain metastases unless treated, asymptomatic, stable, and not requiring continuous corticosteroids at a dose of > 10 mg prednisone/day or equivalent for at least 4 weeks prior to start of study.
• Active infection including tuberculosis and HBV, HCV or HIV
• History of (non-infectious) ILD/pneumonitis that required steroids, has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening.
• Clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses

This is a first time in human (FTiH) Phase I/IIa, open-label, multi-center study of AZD8205 administered to participants with advanced or metastatic solid malignancies. The study will evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of AZD8205.

The participant will receive a stipend for each completed visit.

This research study is studying a new compound, AZD8205, as a possible treatment for advanced or metastatic solid tumours.