Noxopharm (ASX:NOX) prostate cancer trial - DARRT-1


by Rachael Jones

Noxopharm Limited (ASX:NOX) Chief Medical Officer, Dr Greg van Wyk talks about the first of Noxopharm’s prostate cancer treatment trials, DARRT-1, its interim results and the Company’s current clinical strategy.

Rachael Jones:
Hello I’m Rachael Jones for the Finance News Network. Joining me today from Noxopharm (ASX:NOX) is Chief Medical Officer, Dr Greg van Wyk. Dr van Wyk, welcome to FNN.

Dr Greg van Wyk: Thanks very much for having me Rachael.

Rachael Jones: Noxopharm has just released some encouraging results from one of its clinical trials. What can you tell me about this?

Dr Greg van Wyk: Men with metastatic castrate resistant prostate cancer, frequently have problematic metastatic lesions at various places in their body, including the bone. And these lesions are frequently treated with low dose palliative radiation, to improve the symptoms associated with those lesions. So for example, improving pain. DARRT, which stands for Direct and Abscopal Response to Radiotherapy, is a study aimed at assessing whether Veyonda, in combination with external beam radiation at low doses, can improve outcomes for these patients. And also, whether it is sufficiently well tolerated and has a favourable safety profile.

Rachael Jones: What results did you see at 12 weeks and what does that mean?

Dr Greg van Wyk: The first critical thing that we saw is that Veyonda, in combination with palliative radiation, appears to be well tolerated and it appears to have a good safety profile. This is critical in any study of course. But in these patients who really are at the end of their life, and who are undergoing this treatment really to help improve their quality of life, towards the end of their life. It’s really critical that medicines that you’re giving them are not actually making them feel worse. So this is a really important outcome for us to have seen.

In terms of efficacy, we’ve seen encouraging signals as well, particularly at the 800 and 1200-milligram dose levels. In these cohorts, we had four patients in 800-milligram cohort, four patients in the 1200-milligram cohort. And what we saw there was two patients in each of those cohorts had a response in their prostate specific antigenal PSA. And a response is a reduction of 50 per cent or more from baseline, in these levels. This is a really standard measure, or surrogate measure of response in prostate trials. So that’s encouraging. We saw three patients in the 800-milligram cohorts and two patients in the 1200-milligram cohorts have a meaningful reduction in their pain. And what that is is a reduction of 30 per cent or more on the Brief Pain Inventory.

And the last really encouraging effect is that we saw one patient in 800-milligram cohort have a resist response. What this basically means is that they had a reduction in the size of their tumours overall, of at least 30 per cent. So overall, we’re encouraged by those results. And what makes us most encouraged is that in this palliative study, where we were giving low doses of radiation to a single metastatic lesion. For us to have seen these responses to PSA and in terms of tumour size, gives us confidence that what’s driving that pain reduction, is actually an anti-tumour effect.

Rachael Jones: How does the DARRT-1 trial compare to the LuPIN study being held at St Vincent’s Hospital, under Professor Louise Emmett?

Dr Greg van Wyk: They both have similarities and then there are some distinct differences between the studies. So firstly, what they share in common is that they’re studying patients, who have metastatic castrate resistant prostate cancer and have really exhausted other treatment options. Some of the fundamental differences, however, are that the form of radiation in DARRT-1 is what we call external beam radiation. Whereas in LuPIN, patients are injected with a radiopharmaceutical called Lutetium-PSMA.

Those two treatments really differ as well in terms of the doses. So Lutetium-PSMA is given at doses that are intended to be therapeutic, or really prolong life. So they’re given at a full dose. Whereas with the external beam radiation given in DARRT-1, is patients are given low levels of palliative radiation. Not designed to increase patients’ longevity, but really to help them with their pain and keep them comfortable.

One additional difference is that in LuPIN, the study at St Vincent’s, patients were given 400-milligrams or 800-milligrams and then a dose decision was made from there, to increase the size of the sample. And Professor Emmett chose 800-milligrams for that expansion, whereas in DARRT-1, we have an additional dose level of 1200-milligrams. And as it so happens, our data safety monitoring board selected the 1200-milligram dose, to be the dose that additional 12 patients are given in the remaining study.

Rachael Jones: What are Noxopharm’s next steps for studying prostate cancer?

Dr Greg van Wyk: Our goal for Veyonda is to make Veyonda an essential adjunct to radiotherapy, in all its forms in patients with prostate cancer, at various stages of their treatment journey. So what that means is we’d like to follow up DARRT-1 with a phase 2b, or proof of concept study, where we randomise patients and we have a control arm. To really prove the concept of whether adding Veyonda to radiation in the setting, adds benefit for patients.

Additionally, we’re aiming to follow up the LuPIN study being conducted at St Vincent’s, with a proof of concept study for Theranostics or Lutetium-PSMA, in combination with Veyonda. And then in due course, our goal is to bring Veyonda earlier in the treatment continuum. So perhaps to study it in patients with non-metastatic disease, or patients who have metastatic disease, but whose tumour is still responsive to androgen deprivation therapy.

Rachael Jones: Do you have plans outside of prostate cancer and if so, what are they?

Dr Greg van Wyk: Prostate cancer really is our primary objective for Veyonda. We’d like to bring Veyonda to market as a game changer in treating prostate cancer, with all forms of radiotherapy. From a strategic perspective, however, it really makes sense for us to have a diversifying strategy. And therein we are looking at other tumour types, principally sarcoma, which we believe gives us a real opportunity to discharge much of the technical risk of studying Veyonda.

Rachael Jones: Dr Greg van Wyk, thanks for the update.

Dr Greg van Wyk: Thanks very much for having me.