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 III trial studies how well active surveillance help doctors to monitor subjects with low risk germ cell tumors for recurrence after their tumor is removed. When the germ cell tumor has spread outside of the organ in which it developed, it is considered metastatic. Chemotherapy drugs, such as bleomycin, carboplatin, etoposide, and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. The trial studies whether carboplatin or cisplatin is the preferred chemotherapy to use in treating metastatic standard risk germ cell tumors.