For the first time in history, a man has been cured of HIV. The patient, 42-year old Timothy Ray Brown was first hospitalized at Berlin at Germany’s Charite Universitatsmedizin hospital after he contracted acute myeloid leukemia in 2007. He underwent aggressive chemotherapy that destroyed the majority of his immune cells and finally, went through a risky stem-cell transplant that appears to have completely cured Brown of HIV.

The key to this particular case was in the stem cell donor, who had a rare genetic mutation called CCR5 delta 32 homozygosity that is associated with a reduced risk of becoming infected with HIV. While Brown’s own immune system was shot, the donor’s cells were effective enough so that three years later, Brown was completely cured.

The treatment was life-threatening and not something many HIV patients would want to go through, but it opens up new avenues of research into gene therapies and stem cell treatments that may otherwise have been thought hopeless. And while no longer considered as maliciously fatal, HIV patients still live a life rife with pain and hardship. This case is monumental because for the first time in human history, we know that it’s possible to cure HIV and that is awe-inspiring.

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