Doctors said a London man with HIV has become the second known adult in the world to be apparently cleared of the infection since the global epidemic began decades ago, giving hope for a potential cure for AIDS.

Doctors said that recent tests showed no trace of the man’s previous HIV infection. The milestone came about three years after the man received bone marrow stem cells from an HIV-resistant donor and about a year and a half after coming off antiretroviral drugs. The patient was receiving the bone marrow transplant for cancer.

The case offers hope that researchers will soon find a cure for AIDS. But doctors cautioned against calling the patient’s results a cure for HIV, the virus that causes AIDS.

Ravindra Gupta, an HIV biologist who helped treat the man, told Reuters that his patient is “in remission” but warned that it’s “too early to say he’s cured.”

The man has chosen to remain anonymous, with scientists referring to him as “the London patient.” The title is similar to the first known case of a cured HIV-positive patient. Timothy Brown, an American man, was known as “the Berlin patient” when he also received a bone marrow transplant for leukemia treatment in Germany 12 years ago. That transplant also appeared to clear his HIV infection.