A second patient clearing HIV after a bone-marrow transplant confirmed the first cure wasn’t an anomaly — and gave researchers something real to build on. The procedure replaced the patient’s immune cells with donor cells carrying a mutation that blocks HIV from entering the body, but it remains risky, expensive, and limited to those already requiring it for cancer. Still, the case is quietly reshaping what scientists believe is possible, pointing gene therapy research toward a future that doesn’t require a transplant at all.