Oncolytics Biotech Inc. (Oncolytics), a Calgary-based biotechnology company focused on the development of oncolytic viruses as potential cancer therapeutics, has reported initial positive top line data from the first endpoint in its double-blinded randomized phase III clinical study examining Reolysin in combination with carboplatin and paclitaxel in second-line patients with platinum-refractory, taxane-naïve head and neck cancers (REO 018).

The endpoint examines initial percentage tumour changes between the pre-treatment and first post-treatment scans (typically performed at six weeks post-first treatment) of all patients enrolled in the study. The analysis was designed to assess early differences in response between loco-regional tumours and metastatic tumours, as classified and observed by the investigators. This is the first, and to this point only, endpoint to be un-blinded for this study.

The first analysis compared the relative percentages of patients in the test and control arms with tumours that had either stabilized or exhibited shrinkage. For the purposes of this endpoint, the definition of tumour stabilization was restricted to zero percent growth only. Of the 105 total patients with evaluable metastatic tumours, 86 per cent (n=50) of those in the test arm of the study exhibited tumour stabilization or shrinkage, compared with 67 per cent of patients (n=55) in the control arm. This was statistically significant, with a p-value of 0.025.

The second analysis examined the magnitude of tumour response on a per patient basis using a comparison of percentage tumour shrinkage at six weeks in each patient with evaluable metastatic tumours. This analysis showed that Reolysin in combination with carboplatin and paclitaxel was statistically significantly better than carboplatin and paclitaxel alone at stabilizing or shrinking metastatic tumours, yielding a p-value of 0.03.

At the six week point, there is a numeric trend in favour of the test group towards differing activity between the test and control groups in patients with loco-regional tumours.

In an intragroup analysis of the test arm, an improvement in the percentage of patients' metastatic tumours over loco-regional tumours was noted (p=0.083) and an improvement of magnitude of response in metastatic tumours over loco-regional tumours was also noted (p=0.13). By contrast, in an intragroup analysis of the control arm, no statistical differences were noted between the responses of patients with evaluable metastatic tumours and patients with evaluable loco-regional tumours.

"To the best of our knowledge, this is the first successful double-blinded randomized data from a clinical study using an intravenously-administered oncolytic virus. We are delighted to have obtained statistically significant data for Reolysin in a randomized clinical setting," said Dr. Brad Thompson, president and CEO of Oncolytics. "We continue to await the data for the other endpoints of this study, to which all parties still remain blinded at this point."