France-based Atlab Pharma has reported positive data from a Phase II study of ATL101 (Lutetium-177 anti-PSMA antibody), conducted in patients with progressive metastatic castrate-resistant prostate cancer (mCRPC).
A statistically significant relationship between injected dose and antitumor activity was observed in the study, which demonstrated a favourable safety profile.
Atlab medical affairs head Professor Jean-François Chatal said the results signify the safety and the antitumor activity of ATL101 in mCRPC.
"ATL101 shows a steep dose effect on antitumor activity as expected from its radiotherapy mode of action and a potential in prolonging the life of patients with metastatic prostate cancer," Chatal said.
ATL101 was administered as a single intravenous injection at two radioactivity dose levels, 65mCi/m² or 70mCi/m², in two planned consecutive cohorts of the study enrolling 15 and 17 mCRPC patients respectively.
Later, a third expansion cohort of 15 patients was added at the 70mCi/m² dose.
According to the data, all patients had failed up to four hormonal therapies and 55% had also failed at least one docetaxel containing chemotherapy regimen.
An increase from 13% of patients in cohort 1 to 47% in cohort 2 achieving PSA decline over 30% was observed.
Cohort 3 also showed a 30% PSA decline in 47% of patients.
The study observed treatment effect on the circulating tumour cells (CTC) count.
The study, in which the treatment was well-tolerated, showed significant improvement in median overall survival from 11.9 months in cohort 1 to 21.8 months in cohorts 2 and 3.