US-based pharma company Panacea Pharmaceuticals has enrolled the first patient on its phase 1 clinical trial investigating its first-in-class vaccine for persistent prostate cancer.

The four-site trial, being carried out in centres in Alabama, California, Nebraska and South Carolina, is investigating Panacea’s PAN-301-1 candidate – a vaccine that stimulates the immune system to destroy prostate cancer cells.

PAN-301-1’s main ingredients are nanoparticles of a molecule called human aspartyl β-hydroxylase (HAAH) – an enzyme that is expressed by cells during the development of a fetus. It helps cells grow, move and interact with each other to create tissue.

At the time of birth, this enzyme is silenced, however, it has been shown to be expressed in over 20 different adults cancers where it helps cancer cells grow, move and invade tissues.

Cell studies have shown that introducing the gene responsible for producing HAAH into normal cells makes them act like cancer cells, whilst inhibiting HAAH in cancer cells results in them behaving like normal cells.

The vaccine works by introducing hundreds of nanoparticles that have fragments of the HAAH molecule attached to their surface via an injection. The fragments of HAAH result in an immune response that produces anti-HAAH antibodies capable of inhibiting HAAH. These antibodies then inhibit the function of any HAAH molecules expressed by treatment-resistant prostate cancer cells.

Pre-clinical studies of the vaccine in mice expressing HAAH similar to how humans do have shown it to be highly effective in inhibiting tumour growth and metastasis.

“Based on data from the American Cancer Society, there are more than 160,000 cases of prostate cancer anticipated in 2017 and approximately 30 percent of men treated will relapse after five years, with limited treatment options for patients living with persistent prostate cancer,” said Luke Nordquist, Lead Principal Investigator for the study. “HAAH provides a new potential treatment pathway for patients living with persistent prostate cancer, and with the enrolment of the first patient at our centre, we are eager to understand the safety and immunogenicity for PAN-301-1 to address this unmet medical need in cancer diagnosis and treatment.”

In its phase 1 trial, PAN-301-1 will be given to relapsed prostate cancer patients using a fixed-dose escalation scheme every 21 days. This will help establish the recommended dose to use for phase 2 trials. Around 18 patients will be enrolled in the phase 1 trial.

“At Panacea, we have created a promising new vaccine therapy drug candidate that targets a specific and novel cancer-relevant marker, overcoming self-tolerance, yet avoiding autoimmune-like side effects of check-point inhibitors throughout our pre-clinical studies,” said Hossein Ghanbari, President, CEO and Chief Science Officer at Panacea Pharmaceuticals. “The initiation of the Phase 1 PAN-301-1 serves as a starting point for utilising HAAH in treatment to prevent the recurrence of cancer.”