A Study to Learn How Safe the Study Drug BAY 2416964 (AhR Inhibitor) in Combination With the Treatment Pembrolizumab is, How This Combination Affects the Body, the Maximum Amount That Can be Given, How it Moves Into, Through and Out of the Body and Its Action Against Advanced Solid Cancers in Adults

Researchers are looking for a better way to treat advanced solid cancers including head and neck cancer, lung cancer and bladder cancer.

In some people with cancer a protein called Aryl Hydrocarbon Receptor (AhR) can prevent immune cells from fighting tumor cells. The study drug, BAY 2416964, is a small molecule which blocks the AhR allowing the body to use its immune response against the cancer cells. Researchers think that BAY 2416964 given together with a cancer treatment called pembrolizumab may help shrink tumors in people with cancer.

The main aims of this study are to find for BAY 2416964 in combination with pembrolizumab,

• how safe this drug combination is

• how it affects the body (also referred to as tolerability)

• the highest amount of BAY 2416964 that can be given in combination with pembrolizumab without too many side effects.

The researchers will also study the action of BAY 2416964 in combination with pembrolizumab against the cancer.

The participants in this study will get BAY 2416964 and pembrolizumab. BAY 2416964 will be given by mouth. Pembrolizumab will be given as an intravenous (IV) infusion. An IV infusion is given through a needle into a vein.

This study will have two parts. The first part will help find the most appropriate dose that can be given in the second part.

Each participant of the first, so called dose escalation part, will be assigned to one specific dose group for BAY 2416964. The amount of BAY 2416964 that is given changes step-wise from one group to the next. The dose of pembrolizumab will always be the same.

The participants of the second, so called dose expansion part, will receive the most appropriate dose of BAY 2416964 found in the first part.

During the study, the participants will receive the treatment in 3-week periods called cycles. In each cycle, the participants will in general get pembrolizumab once and BAY 2416964 in a daily schedule. These 3-week cycles will be repeated throughout the trial. The participants can take the study treatment until their cancer gets worse, until they have medical problems, or until they leave the trial. Participants will have around 4 visits in each cycle. Some of the visits can also be done via phone.

During the study, the study doctors and their team will:

• take blood and urine samples

• check if the participants' cancer has changed in size using computed tomography scans or magnetic resonance imaging scans of the participants' tumors

• check the participants' overall health

• ask the participants questions about how they are feeling and what adverse events they are having.

An adverse event is any medical problem that a participant has during a study. Doctors keep track of all adverse events that happen in studies, even if they do not think the adverse events might be related to the study treatments.