This study is researching an investigational drug called marlotamig (REGN7075) by itself and in combination with cemiplimab with or without chemotherapy. The study is focused on patients with certain solid tumors that are in an advanced stage.

The aim of the study is to see how safe and tolerable marlotamig is by itself and in combination with cemiplimab (with or without chemotherapy), and to find out what is the best dose of marlotamig to be given to patients with advanced solid tumors when combined with cemiplimab (with or without chemotherapy). Another aim of the study is to see how effective marlotamig by itself, or in combination with cemiplimab (with or without chemotherapy), is at treating cancer patients.

The study is also looking at:

* Side effects that may be experienced by people taking marlotamig by itself and in combination with cemiplimab with or without chemotherapy
* How marlotamig works in the body by itself and in combination with cemiplimab with or without chemotherapy
* How much marlotamig is present in the blood when given by itself and in combination with cemiplimab with or without chemotherapy
* To see if marlotamig by itself and in combination with cemiplimab with or without chemotherapy works to treat cancer by controlling the proliferation of tumor cells to shrink the tumor
* Whether the body makes antibodies against the study drugs (marlotamig and cemiplimab) (which could make the drug less effective or could lead to side effects)

This phase I/II trial tests the safety and efficacy of split-course adaptive radiation therapy in combination with immunotherapy with or without chemotherapy for the treatment of patients with stage IV lung cancer or lung cancer that that has spread to nearby tissue or lymph nodes (locally advanced). Radiation therapy is a standard cancer treatment that uses high energy rays to kill cancer cells and shrink tumors. Split-course adaptive radiation therapy uses patient disease response to alter the intensity of the radiation therapy. Immunotherapy with monoclonal antibodies such as pembrolizumab, ipilimumab, cemiplimab, atezolizumab or nivolumab may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Chemotherapy drugs like carboplatin, pemetrexed, and paclitaxel work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving split-course adaptive radiation therapy with standard treatments like immunotherapy and chemotherapy may be more effective at treating stage IV or locally advanced lung cancer than giving them alone.