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Cancer-fighting virus currently undergoing human trials

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An Australian biotech is hoping for success with its attempt to turn a virus into a cancer fighter after its first patient was dosed in a Los Angeles hospital last month.

Imugene chief executive Leslie Chong told AAP that City of Hope cancer research hospital has additional patients with metastatic solid tumours waiting to take the modified vaccinia virus, which is most famous for being used in the modern smallpox vaccine.

“The FDA has mandated that you have to wait 28 days before you can dose another patient, because you really want to have that safety profile,” Ms Chong said, referring to the US Food and Drug Administration.

“So we’re just simply waiting for those 28 days. I’m always pleased when I don’t hear anything, because that means that the patient had lots of safety, and we haven ‘t heard anything – so we’re really pleased.”

Outside of the movies, using a virus to fight cancer or disease – what’s known as an oncolytic virus – isn’t actually new.

Several are in development, with Amgen’s Imlygic, a genetically engineered herpes virus, the first to win approval. It has been used to treat inoperable melanoma in the United States and Europe since 2015 and from the following year in Australia.

Also, an oncolytic virus candidate known as Cavatak, based on a common cold virus and developed at the University of Newcastle, led to the acquisition of ASX-listed Viralytics in 2018 by US drug giant Merck for $502 million. That therapy candidate is still in clinical trials.

City of Hope surgical oncologist Yuman Fong developed the virus therapy that Imugene has licensed, known as CF33-hNIS or Vaxinia.

“For 30 years now, he’s been creating viruses,” Ms Chong said. “For this one, he made sure it wasn’t too attenuated, meaning that you didn’ t add a lot of things to make it safe.

“He ju st took a pure killing virus that only likes to replicate in malignant cells, solid tumour cells, it simply does not replicate within healthy cells,” and combined it with other several viruses.

Ms Chong said the virus is known as CF33 because it’s the 33rd virus that Dr Fong created, and the most potent against cancer cells. It’s been tested on thousands of animals to ensure the virus doesn’t infiltrate into healthy cells, she said.

The goal is to recruit 100 patients with advanced solid tumours from about 10 trial sites in the United States and Australia, with the patients receiving Vaxinia via an intravenous or intratumoral injection alone or in conjunction with Merck’s anti-cancer drug Keytruda.

The trial is a Phase 1 study, which are usually just aimed at establishing safety and the best dosing levels in preparation for larger clinical trials, which are still many years away. Still, Ms Chong was optimistic that Imugene might receive some effectiveness data when this study concludes in about 24 months.

“It will be in small numbers of course, but given that we saw so much efficacy in the animals, if any of what happened in the pre-clinical models happens in the clinic, I think we have every right to be quite excited about it,” she said.

Ben Miles, a PhD physicist turned entrepreneur, says there are a number of possible problems to overcome, including a patient’s own immune system clearing the virus before any cancer-fighting effects could be realised.

“The reality check here is that 90 per cent of new therapies fail to make it through clinical trials,” he said during a deep dive on Vaxinia published on social media.

But, he added, “oncolytic viruses are a tool set that we are only just learning to control, and I can’t see a future where they don’t have some clinical value in tackling diseases, whether that’s cancer, or something else.”

Original content from AAP. Note: Content has been edited for style and length.

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