The goal of this clinical trial is to learn if KQB198 works to treat advanced hematologic malignancies in adults. It will also learn about the safety of KQB198. The main questions it aims to answer are:

• What is the safe dose of KQB198 by itself or in combination with other anti-cancer drugs?
• Does KQB198 alone or in combination with other anti-cancer drugs decrease the size of the tumor?
• What happens to KQB198 in the body?

Participants will:

• Take KQB198 daily, alone or in combination with another anti-cancer drug
• Visit the clinic about 8 times in the first 8 weeks, and then once every 4 weeks after that

Inclusion Criteria:

• Adequate organ function

Part 1 and Part 2, Cohort B Participants Only:

• Ph+ CML in chronic phase who have been previously treated with at least 2 different tyrosine kinase inhibitors (TKIs) and are relapsed from or intolerant to those TKIs and ineligible for alternative therapeutic options likely to produce clinical benefit as determined by the investigator.

Part 2, Cohort A Participants Only:

• Participants with Ph+ CML in chronic phase who are on dasatinib prior to study entry and have a warning or failure to dasatinib as determined by the investigator per ELN 2020 guidelines

Exclusion Criteria:

• CML in accelerated or blast phase
• Prior therapy with a similar mechanism of action to KQB198
• History of intestinal disease, inflammatory bowel disease, major gastric surgery, or other gastrointestinal conditions likely to alter absorption of study treatment or result in inability to swallow
• History of interstitial lung disease
• Cardiac abnormalities