Can HIV Drugs Help Slow Advanced Cancers?

By Alan Moses
HealthDay Reporter

THURSDAY, April 7, 2022 (HealthDay News) — The introduction of HAART (highly active antiretroviral therapy) in the mid-1990s revolutionized HIV/AIDS treatment, halting disease progression and dramatically extending lives .

Now, a small new study suggests another potential use for one of the standard HAART drugs: It halted disease progression in about a quarter of patients battling advanced colon cancer.

“The most surprising thing is that this is a class of drugs that we have been using effectively against viruses for many years,” said study author Dr. David Ting. “And now this study opens up the opportunity to develop this class of drugs for cancer.

“We’re still trying to understand why some patients may benefit more than others,” said Ting, director of the Tumor Cartography Center at Massachusetts General Hospital Cancer Center in Boston.

Ting acknowledged that more research will be needed, but described the findings as “exciting”, adding that in addition to colon cancer, it seems likely that “this [drug] strategy may be effective in multiple cancers.”

Ting noted that HAART treatment for HIV patients — which is usually given as a combination of several drugs — targets specific proteins called “reverse transcriptases” (RT).

That’s because HIV needs RTs to replicate and spread.

†[But] we and others have previously found that RT proteins in human cells are reactivated in cancer,” explains Ting, also an associate professor of medicine at Harvard Medical School. “That’s why these RT drugs are for HIV [also] have the ability to block these human RTs found in cancer.”

To underscore that point, Ting highlighted a 2018 research paper that found that patients living with HIV while undergoing three-drug HAART therapy actually have a significantly lower incidence of many cancers than the general population. That lower risk, researchers found, includes breast, prostate and colon cancers.

For the new study, Ting and his colleagues examined the potential of just one commonly used HAART medication: lamivudine.

The trial involved 32 patients, all of whom had been diagnosed with advanced colon cancer that had spread widely despite a series of standard but unsuccessful cancer treatments.

Ultimately, all patients received lamivudine, but at significantly higher doses — nearly 400% more — than is usually given to HIV patients. (HAART drugs are known to be “well-tolerated” in HIV patients, Ting said, although he cautioned that it remains to be seen whether higher doses could give rise to new side effects.)

Lamivudine was administered without any other cancer therapy. The result, Ting noted, was that eight of the patients saw their cancer’s progression stall, while one more achieved a “mixed response.”

None of the patients saw their tumors shrink. But the team did observe encouraging “biological changes in the tumors when we looked at biopsies before and after treatment,” Ting said.

The findings were recently published in the journal Cancer Discovery.

The progression-stopping impact that the HAART medications appeared to have on colon cancer suggests that “tumors behave in a virus-like manner,” said study co-author Benjamin Greenbaum, a contributor to the computer oncology service at Memorial Sloan Kettering Cancer Center in New York City.

In fact, Greenbaum said, lamivudine’s impact on tumor cells is so similar to its impact on HIV that it amounts to a “surprising” form of “viral mimicry.”

Still, the majority of patients did not seem to benefit. Ting suggested it could in theory be because of different amounts of RT proteins found in individual patients’ cancer cells.

“We are trying to better understand which cancers are more dependent on this RT activity so that we can have more precision in the patients who could benefit from this therapy,” he said, stressing that the prospects for this type of cancer intervention are ” still in its infancy.”

Yet said Dr. Andrew Chan — a professor of medicine at Harvard Medical School and vice chair of gastroenterology at Massachusetts General Hospital — said the possibility of using HAART drugs to treat advanced cancer “would be a new target for treatment, which is really exciting, especially if we can reuse existing drugs for other conditions for which we have a wealth of clinical experience.”

More information

There’s more on the link between HIV and cancer risk at the US National Cancer Institute.

SOURCES: David Ting, MD, associate clinical director, innovation and director, Tumor Cartography Center, Massachusetts General Hospital Cancer Center, and associate professor of medicine, Harvard Medical School, Boston; Benjamin Greenbaum, PhD, attending associate, computer oncology service, Memorial Sloan Kettering Cancer Center, New York City; Andrew Chan, MD, MPH, professor, division of medicine, Harvard Medical School and vice chairman, gastroenterology, Massachusetts General Hospital; Cancer Discovery, March 23, 2022

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