Can a second drug wipe out hidden leukemia cells?

This trial tests whether adding rituximab to the standard drug cladribine can eliminate leftover cancer cells in people with hairy cell leukemia, a rare blood cancer. Half the participants receive both drugs at the start, while the other half get rituximab later only if needed. The goal is to see which approach better clears minimal residual disease—the small number of cancer cells that can remain after treatment and raise the risk of relapse.