The goal of this clinical trial is to learn if investigational agent LRK-4189 works to treat solid tumors in adults, with a focus on colorectal cancer. It will also learn about the safety of drug LRK-4189.

The main questions it aims to answer are:

Is LRK-4189, administered alone or in combination with standard chemotherapy regimens, safe and tolerable in patients with solid tumors?

Participants will:

• Take investigational agent LRK-4189 alone or in combination with standard chemotherapy regimens every day for up to 3 years.
• Visit the clinic once every week for checkups and tests.

Inclusion Criteria:

• Willing and able to sign the study consent form and take part in all required study visits, tests, and procedures.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.
• Have a locally advanced or metastatic cancer that cannot be removed with surgery and has gotten worse despite treatment.
• Cancer can be measured on scans, such as CT or MRI.
• Willing to have tumor biopsies, meaning small samples of your tumor will be collected during the study.
• Heart rhythm test (ECG) shows a normal result within safe limits.
• Blood test results at screening are within an acceptable and stable range.
• If you are a woman, you are not able to become pregnant, or you agree not to become pregnant during the study and to use approved birth control methods.
• If you are a man, you agree not to donate sperm during the study. If you have sex with a partner who could become pregnant, you agree to use approved birth control methods during the study.

Exclusion Criteria:

• Unable to swallow the study medication or your body cannot absorb it.
• Have had a serious allergic reaction to LRK-4189 or any of its ingredients.
• Have needed a fluid drainage procedure from the chest or abdomen within the past 6 weeks.
• Have active cancer in the brain or spinal fluid, or brain tumors that require steroid treatment.
• Currently receiving another cancer treatment.
• Have an active HIV, hepatitis B, or hepatitis C infection with detectable virus levels.
• Have an active infection that requires treatment through a vein (IV).
• Taking certain medications that strongly interact with the study drug and cannot stop them at least 14 days before starting the study.
• Pregnant or breastfeeding or planning to become pregnant or father a child during the study.
• Cannot safely receive the standard chemotherapy that would be used with this study.