Noxopharm to commence NOX66 cancer study at St Vincent’s Hospital

Noxopharm (ASX: NOX) has announced the involvement of its experimental drug, NOX66, in a clinical study looking at the ability of a pioneering form of radiotherapy to boost survival prospects in men with late-stage prostate cancer.

Key Points:

• Combination of NOX66 + pioneering form of radiotherapy
• Late-stage prostate cancer patients
• Safety and efficacy study

NOX66 study summary

The Phase 1 Investigator-Initiated study is being run at St Vincent’s Hospital, Sydney, with nuclear medicine specialist, Dr Louise Emmett, as Principal Investigator.

The study will test the safety and efficacy of NOX66 in combination with an experimental form of radiotherapy in men with metastatic, castrate-resistant prostate cancer that has failed to respond to all standard therapies and who have limited survival prospects.

Radiotherapy is a standard first-line therapy in early-stage prostate cancer, but generally only used for symptom relief in late-stage prostate cancer.

Noxopharm is developing NOX66 as a radio-sensitising drug intended to convert a palliative effect of radiotherapy in most forms of late-stage cancer into a meaningful clinical effect providing a significant survival advantage.

This study will involve 30 men and recruitment is expected to commence in mid-June.

Rationale

NOX66 is a first-in-class sensitiser of both chemotherapy and radiotherapy in cancer cells only.

The active ingredient, idronoxil, sensitises cancer cells to radiation by blocking their ability to repair the DNA damage caused by the radiation.

That DNA repair process continues for about 1 week following radiotherapy, with cancer cells either dying or recovering depending on their capacity to repair the damage.

The purpose of idronoxil is to block that repair capacity, resulting in cancer cells with even minor DNA damage being killed.

Noxopharm is undertaking a clinical program of 3 clinical trials evaluating the radio-sensitising capacity of NOX66 across the 3 main forms of radiotherapy used in the treatment of late-stage prostate cancer –

(i) standard external beam radiotherapy,

(ii) stereotactic body radiotherapy, and

(iii) brachytherapy.

The current study is the first of these 3 to commence and involves brachytherapy, or where the source of radiation is placed internally within the body either inside or near to the cancer.

Radiotherapy brachytherapy

The St Vincent’s Hospital study is using an experimental radioactive drug known as 177lutetium-PSMA peptide complex (LuPSMA). LuPSMA is injected intravenously and has been shown to be effective at locating pockets of prostate cancer cells throughout the body, including clusters of cancer cells too small to be seen by standard methods of scanning. The drug serves as a Trojan Horse, delivering small doses of a radioactive emitter directly to the prostate cancer cells.

The new study is an extension of a pilot study conducted recently by St Vincent’s Hospital in conjunction with the Peter MacCallum Cancer Centre, Melbourne.

That earlier study was successful in providing proof-of-concept of the ability of LuPSMA to attack lesions in men with late-stage prostate cancer, with most men showing a clinical response in terms of a reduction in both the size and number of cancer lesions.

However, that response in most men was incomplete and relatively short-lasting. The objective of the new study is to use NOX66 to achieve a more complete and a longer-lasting response.