Last March, scientists announced that Mr. Castillejo, then identified only as the “London Patient,” had been cured of H.I.V. after receiving a bone-marrow transplant for his lymphoma. The donor carried a mutation that impeded the ability of H.I.V. to enter cells, so the transplant essentially replaced Mr. Castillejo’s immune system with one resistant to the virus. The approach, though effective in his case, was intended to cure his cancer and is not a practical option for the widespread curing of H.I.V. because of the risks involved.
…He had been experiencing fevers, and the tests showed that they were the result of a Stage 4 lymphoma. “I will never forget my reaction as once again my world changed forever,” he said. “Once again, another death sentence.”
Years of harsh chemotherapy followed. Mr. Castillejo’s H.I.V. status complicated matters. Each time his oncologists adjusted his cancer treatment, the infectious-disease doctors had to recalibrate his H.I.V. medications, said Dr. Simon Edwards, who acted as a liaison between the two teams.
…They discovered that at a hospital in London was Dr. Ian Gabriel, an expert in bone-marrow transplants for treating cancer, including in people with H.I.V. Because of their last-ditch effort, Mr. Castillejo said, “We’re here today. You never, never know.”
Within a week, he met with Dr. Gabriel, who tried a third and final time to tap Mr. Castillejo’s own stem cells for a transplant. When that failed, Dr. Gabriel explained that Mr. Castillejo’s Latin background might complicate the search for a bone-marrow donor who matched the genetic profile of his immune system. To everyone’s surprise, however, Mr. Castillejo quickly matched with several donors, including a German one — perhaps a legacy from his half-Dutch father — who carried a crucial mutation called delta 32 that hinders H.I.V. infection.
…A year on, as he became stronger, he slowly began thinking about forgoing the H.I.V. medications to see if he was rid of the virus. He took his last set of antiretroviral drugs in October 2017. Seventeen months later, in March 2019, Dr. Gupta announced the news of his cure.
…So far, his body has shown no evidence of the virus apart from fragments the doctors call “fossils” and what seems to be a long-term biological memory of having once been infected.