Australian biotech drug developer Noxopharm (ASX: NOX) has reported positive interim results from its LuPIN study involving the Veyonda drug developed for men with late stage metastatic, castration-resistant prostate cancer.
Veyonda (previously known as NOX66) – and specifically 177Lutetium-PSMA-617 – is being used to see if its radio-enhancing and immuno-stimulatory properties will increase the rate of response (whereby more men are able to complete the full course of treatment) and the durability of the response (meaning a longer time before the disease progresses).
177Lu-PSMA-617 is an experimental radiopharmaceutical comprising a peptide which delivers the radioactive isotope, 177lutetium, directly to prostate cancer cells via intravenous injection.
The peptide seeks out prostate cancer cells throughout the body, with the attached 177lutetium then delivering radioactive damage to the cancer cell.
Response to treatment includes shrinkage and even complete remission of metastases throughout the body, although responses in most men are relatively short-lived.
As an emerging and promising form of treatment for late-stage cancer, Noxopharm considered the rate and durability of response end-points during the LuPIN study to be key to the treatment being widely adopted by patients and the medical profession.
PSA response rate
The LuPIN study is a Phase 1b investigator-initiated clinical trial being run at St Vincent’s Hospital in Sydney, involving 32 men with metastatic, castration-resistant prostate cancer where the disease is end-stage and progressing despite treatment.
The men receive up to six courses of treatment with Veyonda and 177Lu-PSMA-617 at six-weekly intervals, where 177Lu-PSMA-617 is delivered via injection and Veyonda administered for the first 10 days of each cycle.
The first 16 male subjects in the study received two or more doses of 177Lu-PSMA-617 and four have already completed the planned six cycles.
The first eight men received 400 milligram doses of the drug and following a safety data review, the dose for the remaining patients was increased to 800mg doses.
At the interim stage of the study, Noxopharm said the success of Veyonda is being measured by its effect on the prostate-specific antigen (PSA) response rate – a standard, FDA-recognised measure of response in prostate cancer, defined as a >50% overall reduction in PSA – as well as its tolerability and safety profile.
“The PSA response rates for the first eight patients on 400mg and the remaining eight on 800mg dosages were 62.5% and 75% respectively, producing an overall PSA response rate of 69%,” the company said in a study report.
“The overall response rate – and particularly the response rate in the 800mg cohort – compared favourably with PSA response rates of 177Lu-PSMA-617 alone (ranging between 31% and 61%) in 10 previously-published trials.”
To date, Noxopharm said the increased response rate had been achieved in a “generally well-tolerated way”, with only one severe adverse event (pneumonitis) being reported.
Noxopharm chief executive officer Greg van Wyk had high hopes for the efficacy of 177Lu-PSMA-617 in conjunction with Veyonda.
“While PSA response rates in patients treated with 177Lu-PSMA-617 alone are good, Veyonda was added to explore whether it can increase the rate and durability of response,” he said.
“The data released today is looking positive, as the patients in the first two LuPIN cohorts appear to be deriving benefit beyond that which would be expected with 177Lu-PSMA-617 alone.”
177Lu-PSMA-617 has been under assessment for the past five years on an experimental basis in Germany and Australia using as its subjects several thousand men with end-stage prostate cancer and no remaining treatment options.
Mr van Wyk said St Vincent’s is at the global forefront of evaluating radiopharmaceutical technology and has played a key role in the assessment process for Noxopharm.
At mid-afternoon, Noxopharm shares were trading 20% higher at $0.66.