A man in the United Kingdom has been in remission from HIV, which causes AIDS, for over a year after he received a bone marrow transplant from an HIV-resistant donor, The Guardian reported on Tuesday. He has become the second man to be cleared of the virus.

“There is no virus there that we can measure,” said Ravindra Gupta, a professor and HIV biologist who co-led a team of doctors treating the man. “We can’t detect anything.” Gupta said the man was “functionally cured” and “in remission”, but said it was “too early to say he’s cured”.

The man is being called “the London patient” as his case is similar to the first case of a functional cure of HIV almost 12 years ago. “The Berlin patient” had undergone a similar treatment in Germany in 2007 which cleared his HIV and continues to be HIV free.

Three years ago, the “London patient” had received bone marrow cells from a donor with a genetic mutation, known as CCR5-delta 32, that resists HIV infection. The man has been in remission for 18 months since he stopped taking antiretroviral drugs, according to CNN.

“By achieving remission in a second patient using a similar approach, we have shown that the Berlin Patient was not an anomaly and that it really was the treatment approaches that eliminated HIV in these two people,” said Gupta. He said the treatment used is not appropriate for all patients but it offers hope for new treatment strategies, including gene therapies.

The “London patient” told The New York Times in an email that he never thought there would be a cure “during my lifetime”. “I feel a sense of responsibility to help the doctors understand how it happened so they can develop the science,” he said.