Abscopal response concept
A simple concept, but one that can be challenging for the investor to grasp.
Take the example of a man with late-stage prostate cancer. He has been through all available forms of therapy and the cancer has progressed despite all of those therapies. He has essentially run out of treatment options and is facing some months of palliative therapy leading up to his death.
His cancer has spread to clusters of lymph nodes in his pelvic cavity and abdomen, and throughout his skeleton with dozens (even up to hundreds) of metastases in bones in his legs, arms, ribs and skull. The growing tumour load in his body is draining his health, and the tumours in his bones are causing considerable pain.
Palliative therapy at this point generally involves two main therapies. The first is pain relief. The second is radiotherapy to try and shrink one or two larger tumours that might be pressing on a vital organ or causing particularly bad pain.
Where radiotherapy is used in this palliative setting, it is designed to shrink the offending tumour by killing as many cancer cells as possible. The radiation is restricted to a narrow band because the aim is to limit the amount of damage to healthy tissues. That means that the effect of the radiation is limited just to the 1 or 2 tumours in that tight band of radiation. The tumours in the rest of the body will continue to grow unaffected. Shrinking 1 or 2 targeted tumours in a body containing dozens or even hundreds of tumours won’t be expected to have any effect on the patient’s overall survival time. As the term ‘palliative’ indicates, it is intended to make remaining life as comfortable as possible …. not to extend it.
That’s the blunt way of using radiotherapy. Recent experience shows that there is a smarter way of using radiotherapy in the palliative setting that can go well beyond just providing symptomatic relief, and end up providing a very significant anti-cancer effect and prolonging life to a considerable degree.
This smarter, light-handed approach relies on using a low dose of radiation that instead of seeking to destroy the tumour, seeks instead to inflame and irritate. This triggers an immune response with the aim of generating immune cells within the irradiated tumours now primed to kill the cancer cells. The aim is that these primed immune cells then leave the irradiated tumour, enter the bloodstream, and travel round the body seeking out and destroying other cancer cells.
This phenomenon of applying radiation to one discrete part of the body and then seeing tumours shrinking or disappearing altogether in distant parts of the body where the radiation did not reach is known as an abscopal response.
Low-dose radiation on its own is highly unlikely to result in an abscopal response. It needs help, and that help comes in the form of anti-cancer drugs (known as immuno-oncology drugs) that work by promoting the immune system. Radiation alone and immuno-oncology drugs alone don’t deliver an abscopal response. Together, they can. Not in every case, but hopefully in enough cases to make the effort worthwhile.
What today’s announcement means to a Noxopharm shareholder
It means three things.
The first is that it goes a long way to confirming the potential of Veyonda
Today’s data shows that it is possible to achieve a meaningful anti-cancer effect in men who have exhausted all standard treatment options.
Veyonda is providing an anti-cancer effect in prostate cancer patients that have stopped responding to all other standard anti-cancer drugs, including a number of drugs that in recent years have commanded acquisition prices over US$10 billion. Noxopharm shareholders own a drug candidate that is working where US$10 billion+ drugs have stopped working
The second is that it shows that a treatment that is minimally intrusive and well-tolerated can deliver an important anti-cancer effect
The men involved in DARRT-1 had been through a lot in terms of treatment and, given the extent of their disease, generally were in poor health. Last-gasp therapies that are going to involve a lot of time in hospital and come with a lot of unwanted side-effects are not going to be attractive to such men. The DARRT treatment regimen doesn’t come with those challenges. The DARRT regimen requires minimal time at a radiation oncology clinic and self-medication with Veyonda, and comes with no major side-effects.
This makes Veyonda and the DARRT approach an attractive proposition for patients and doctors and thereby a treatment likely to be taken up
The third is that it brings us one step closer to securing a commercial deal
Today’s data shows that it is possible to achieve an abscopal response in prostate cancer. Others have shown it is possible to get abscopal rates in the 20-30% range in certain other cancers such as breast, lung and kidney cancers and melanoma using combination radiotherapy and immuno-oncology drugs like checkpoint inhibitors. But prostate cancer so far has proved largely unresponsive to the extent that this cancer has developed a reputation as something of a ‘non-immunological’ cancer type.
Today’s data shows that by using the appropriate immuno-oncology drug, in this case Veyonda, abscopal responses are achievable in prostate cancer. That’s a first, because other immuno-oncology drugs haven’t worked to anything like this extent in this cancer. Prostate cancer is a major cancer with an estimated 300,00 expected to die from this cancer this year, something that should put Veyonda on the global M&A radar.