Prima publishes cancer trial results, outlines road ahead

Prima Biomed's (ASX:PRR) results from a phase I clinical trial of its CancerVac MFP technology for advanced adenocarcinoma have been accepted and published in the journal Clinical Cancer Research.

The phase I results encouraged Prima to move to the current phase IIa trial investigating activity of the MFP vaccine in ovarian cancer.

"In the research area [peer review] is the yardstick," said principal investigator Dr Paul Mitchell. "It is one thing to make an announcement in the press, but to be stringently reviewed by other researchers and published means there will be heightened international awareness of Prima Biomed's novel technology,".

Prima completed the phase I study of 10 patients with advanced cancer, including renal, breast, ovarian, colon and non small cell lung cancer in October 2002 and commenced a phase IIa trial of this technology in ovarian cancer in July 2004.

According to Mitchell, the delay in publishing the results was due to very long responses from two patients, one with ovarian and one with renal cancer. "In the trial, all the participants showed a strong immune response," he said. "However, there were two patients who continued to be stable for a considerable length of time. We held off to see how durable the treatment would be and then set up the phase IIa trial based on the results.

"Patients with ovarian cancer represent a group whose tumours may be suited to an immunotherapy approach even in advanced stages of disease. This is because for many patients the cancer is slow to change and gives time for the vaccine strategy to work. Ovarian cancer can also easily be measured in the blood stream and we can pick up small changes to the cancer which means we have a more sensitive end point," he said.

Foreign cells

CancerVac's immunotherapy works by teaching the immune system to recognise the tumour cells as foreign. Dendritic cells are removed from the patient and stimulated with mannan fusion protein (MFP), consisting of the antigenic portion of the tumour antigen mucin-1 (MUC-1) fused to the immune-enhancing sugar mannan. The cells are then reinfused back into the patient to generate primarily a T-cell-based immune response against the MUC-1-expressing tumour.

In the phase IIa trial, markers secreted from the tumour cells, CA-125, are used to indicate the rate and magnitude of clinical response to treatment. In addition patients have CT scans to monitor tumour response as well as analysis of their immune system.

Twenty patients were recruited into the and in late November 2005 the decision was made to recruit further patients.

"We initiated the phase IIa trial this time last year and the recruitment process was always going to take 12 months," explained Prima executive chairman Eugene Kopp. "We elected to continue to recruit 10 more patients late last year to have a statistically meaningful result for registration purposes. We are on track to conclude be the end of February, early March and have interim data some time at the beginning of the next quarter and the final results in September/October.

Move fast

"If the interim results are compelling we are not going to sit and wait for the results to come -- we are going to move as fast as we can to register the product in Australian and New Zealand," Kopp said. "We will initiate discussions with the FDA for phase IIb/III trial and may get an accelerated approval process, but we are assuming a conservative process.

"In parallel, we will be consulting with [Canadian cancer vaccine specialist] Biomira for our overseas trials until they elect to take their exclusive licensing option for North America and the rest of the world, which they can do based on the interim results or at the latest the presentation of data of the phase IIa trial.

"We my also consider taking another indication through the phase IIa trail to broaden the scope of CancerVac applications in other oncology areas including stomach, renal or non-small lung cancer."

Strategic review

This week Prima announced its second quarter results, which revealed that the company has $5.15 million in the bank. "We have more than 12 months of funding, according to current projections," Kopp said. "They don't include phase IIb/III but we are confident we will be able to raise the funds on the back of compelling data.

"We have initiated a strategic review and sold Arthron to [Canadian-based] Trillium late last year. Our subsidiary Panvax is being reviewed by Intersuisse for partnerships, to raise funds or most likely to sell.

"We have a broad view but we need a strong partner to fund the DCtac program. The most likely option is a sell-down, and to maintain some equity in development, as we have done with Arthron. Following the strategic review we may raise further funds and will be exploring AusIndustry grants, particularly for new indications."