For just the second time, a patient with AIDS appears to have been cured of the disease after receiving a stem cell transplant from a donor with a genetic mutation that provides resistance to HIV, which causes AIDS. But the mutation is exceedingly rare, raising controversial questions of whether it may be replicated using nascent gene-editing tools like CRISPR/Cas9.
An anonymous HIV-positive man in the UK known as “the London Patient” shows no signs of the infection three years after receiving bone marrow cells from a donor with a mutation known as CCR5 delta 32, and 18 months after he stopped taking antiretroviral drugs to treat the disease.
“There is no virus there that we can measure. We can’t detect anything,” Ravindra Gupta, a doctor, professor and researcher who helped lead the man’s treatment, told Reuters.
While Gupta said the patient is functionally cured and in remission, he warned that it’s still too early to say a definite cure for AIDS has been found.
The case is the first apparent replication of another in which an American named Timothy Brown – also known as ‘the Berlin Patient’ – was cleared of AIDS after receiving a stem cell transplant in 2007. Brown reportedly continues to live HIV-free in the United States today.
While the two cases could represent a clear breakthrough in the search for a cure to a disease that afflicts millions worldwide, experts caution that a readily available therapy to cure AIDS remains far off. The genetic mutation that appears to have cured the two men is very uncommon and the treatment can be complex and expensive.
One potential solution could be to recreate the rare genetic mutation using relatively new gene-editing tools like CRISPR/Cas9. Researchers have successfully used the tool to confer HIV resistance in mice and last year Chinese researcher He Jiankui created an epic stir when he flouted all sorts of ethical considerations to use CRISPR on human embryos. He claims his work resulted in the birth of twin girls who are resistant to HIV despite having an HIV-positive father.
A review of the potential uses of gene-editing to prevent or cure AIDS was published in December in the journal Frontiers in Microbiology. It raises a number of concerns and challenges when it comes to using these new technologies to take on AIDS, not the least of which are so-called “off-target effects.” Put simply, if CRISPR misses its target it could lead to cancer or other adverse effects.
Still, attempting to replicate the HIV-eradicating effects seen in the Berlin Patient has been the topic of much research over the past decade, but it has been hampered by the lack of any other apparently cured AIDS patients. Now it appears the cure may have finally been duplicated. It’s still early days for both this promising treatment and for gene-editing technology, but work on eventually combining the two may now be able to accelerate.