A Phase 1/2 First-Time-in-Human, Open-label, Multicenter, Dose Escalation and Expansion Study of the Oral DNA Polymerase Theta Inhibitor (POLQi) GSK4524101 and the PARP Inhibitor (PARPi) Niraparib in Adult Participants With Solid Tumors

• GSK4524101 is a POLQ inhibitor

In this study, the sponsor and investigators want to learn:

• How much of the study drug can be given with an acceptable level of side effects
• The effects of the study drug (good and bad)
• How much of the study drug is absorbed into the blood and how fast it is removed
• How the study drug / agent is acting on your body
• If research tests can be used in the future to predict who will benefit from GSK4524101

Part 1 is an open-label, dose escalation study, meaning both you and the study doctor will know which dose of drug you will get. If you join this study, you will get GSK4524101 alone or in combination with niraparib.

You will come to the clinic about 7-8 times in the first two months and once or twice monthly thereafter. For visits where no other assessments are required, you will be provided a blood pressure monitor to measure your pulse rate and blood pressure at home.

You will need to take GSK4524101 twice a day, once in the morning and once in the evening. At the highest doses of GSK4524101, you may need to take up to 10 capsules twice daily. If you are enrolled into a group who will also receive niraparib, you will take niraparib once daily. Treatment may continue as long as your doctor believes you are receiving benefit. If the study drug(s) is not tolerable, your doctor may decide to lower the dose or have you stop taking the drug(s).