Recurrent Hairy Cell Leukemia

This phase II trial studies the side effects and how well cladribine and rituximab work in treating patients with hairy cell leukemia. Drugs used in chemotherapy, such as cladribine, 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. Immunotherapy with monoclonal antibodies, such as rituximab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving cladribine together with rituximab may kill more cancer cells.

This phase I/II trial tests the safety, side effects, and effectiveness of tovorafenib in combination with rituximab in patients with classical hairy cell leukemia (cHCL) that has come back after a period of improvement (recurrent) or that has not responded to previous treatment (refractory) and compares the effect of tovorafenib and rituximab to current standard treatment of cladribine and rituximab in cHCL patients that have not yet received treatment. Tovorafenib blocks certain proteins made by the mutated BRAF gene, which may help keep cancer cells from growing. It is a type of kinase inhibitor. Rituximab is a monoclonal antibody. It binds to a protein called CD20, which is found on B cells (a type of white blood cell) and some types of cancer cells. This may help the immune system kill cancer cells. Cladribine damages the cell's deoxyribonucleic acid and may kill cancer cells. It is a type of antimetabolite. Giving tovorafenib in combination with rituximab may be safe and tolerable and more effective than cladribine with rituximab in treating patients with untreated, recurrent or refractory cHCL.

This phase II trial tests how well venetoclax works in treating patients with hairy cell leukemia that has come back after a period of improvement (relapsed). Venetoclax is in a class of medications called B-cell lymphoma-2 (BCL-2) inhibitors. It may stop the growth of cancer cells by blocking Bcl-2, a protein needed for cancer cell survival.