Cancer drug Keytruda can help ‘smoke out’ dormant HIV

Researchers who examined 32 patients with both cancer and HIV are yet to discover how to eliminate the virus in its latent stage. 

But new early-stage findings published in the journal Science Translational Medicine suggest that besides reviving the immune system and encouraging it to attack tumours, the cancer drug can smoke HIV out of hiding in immune cells.

Dr George Njoroge told the Nation that antiretroviral therapy, the standard treatment for HIV, can remove traces of the virus from what he describes as a hidden reservoir of HIV that persists in patients under treatment.  

Dr Njoroge, a cancer researcher, helped develop Boceprevir (Victrelis), which is used to treat hepatitis C at US pharmaceutical company Merck, which also makes Keytruda.

“As experts, we have been trying to do this for quite some time. There is a phenomenon we call ‘smoking out’ the HIV from their reservoirs,” he said.

“That’s the major problem - they are hiding there and even if you clear the HIV using antiretroviral therapy, the ones in the memory sites will come out and proliferate.”

Highly susceptible

HIV attacks the immune system by infecting white blood cells known as T cells.

Dr Mansoor Saleh, with the department of haematology and oncology at Aga Khan University Hospital (AKUH), said T cells help a patient fight infection, including cancer. 

“In HIV, the virus infects and kills the T cells, which is why the patient becomes immunodeficient,” he said. 

“(That) is why a patient whose T cells have been killed by the HIV virus is highly susceptible to other diseases like malaria, tuberculosis and other infections, apart from being at a higher risk of acquiring other cancers.

“When you take antiretroviral therapy, it kills all the viruses that are drawing in on the T cells, but there are some T cells that are dormant and the virus that infected them is not growing and so if I test your blood for the viral load, it is not detectable,” Dr Saleh explains.

He said he uses Keytruda on his cancer patients.

“When I use Keytruda on patients, it activates the normal T cells to fight the cancer," he said. 

"When I use it on cancer patients who have HIV, Keytruda not only activates … normal T cells to fight the cancer but also activates the dormant T cells which were infected by the HIV virus, which means the dormant T cells now become active.”

The new findings, he said, are good news for HIV patients who are also battling cancer.

Antiretroviral therapy

“The struggle has been that if a patient is on antiretroviral therapy to suppress HIV and I put them on chemotherapy to suppress cancer, combining the two for most patients is a challenge,” he said.

But Keytruda, he said, can be given to cancer patients who are also on antiretroviral therapy.

There is also some bad news apart from the high toxicity that results from combining the two therapies.

“The bad news is that the T cells not only become ‘anti-cancer’, they also become ‘anti-self’ with many of the drugs like Keytruda,” he said.

The toxicity can affect a patient’s liver and skin, he said, adding that this is why more research is needed on the impact of using Keytruda in HIV patients.

AKUH, he said, will start clinical trials soon to find out how Keytruda works in HIV patients.
Dr Njoroge shares Dr Saleh’s sentiments.

“Some of these drugs sometimes over-activate the immune system. “This is why they cannot be used in high quantities and this is what we call cytokine storm,” he said

“Cytokines are small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells and when released, they signal the immune system to do its job.”

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