Patrys Limited which is developing a new class of antibody molecules for the treatment of cancer, has announced the success in obtaining commercial production yields for natural human antibody PAT-SC1, facilitating the advancement of this promising product toward a second human clinical trial for the treatment of cancer. Prior to being acquired by Patrys, PAT-SC1 was evaluated for safety and efficacy in a human clinical trial involving gastric cancer patients.

The results were encouraging, as patients treated with PAT-SC1 experienced a significant survival benefit compared to a historical control set of patients that received similar treatment but for the PAT-SC1 antibody. When acquired, the product was produced using out-dated and low-yielding technology, necessitating a move to Patrys’ newly developed proprietary manufacturing technology for natural human antibodies. That transfer has now occurred, with yields achieved of 4 grams/litre, which far exceeds the commonly cited industry standard for production of an antibody in Phase I/II clinical trials of 1 gram/litre.

The manufacturing programme is conducted at Percivia, a US based joint venture between global bio-pharmaceutical company Crucell N V, a subsidiary of Johnson & Johnson, and leading manufacturing firm DSM Biologics. All data on PAT-SC1 yields was generated by Percivia. “While we were confident Percivia would succeed in achieving targeted yields, this now confirms that PAT-SC1 can be produced in sufficient quantities to support advanced clinical development. We will now focus our efforts on how best to achieve that aim – whether as an internal or partnered programme,” commented Patrys chief executive officer, Dan Devine.

In addition to manufacturing advances, over recent months several researchers from independent laboratories have reported new data pointing to an expanded and critical role of CD55 in cancer, the disease target for PAT-SC1. Among other findings, over the past several months international researchers reported the following (complete citations available below): Cancer cells expressing CD55 are resistant to multi-billion dollar antibody rituximab (Cancer Research).

Inhibition of CD55 clearly sensitises breast, prostate and leukaemia cancer cells to complement attack and therefore could be useful as possible adjuvant to improve antibody-based cancer immunotherapy (Current Cancer Drug Targets). Expressions of CD55 in rectal tumour tissues significantly higher than in normal colorectal tissues, and expression of CD55 correlates with tumour recurrence and metastasis. Expression of CD55 significantly increased in human cervical cancer tissues; inhibition of CD55 enhanced cell death and helped control cancer cell migration.

Late last year PAT-SC1 was confirmed orphan drug status by the United States Food and Drug Administration (FDA), allowing the product to benefit from the potential for fast track development in the United States. This can in turn be leveraged globally where the market is more commercially significant with over 1,000,000 new cases diagnosed each year. Looking forward, Percivia will now turn to optimising upstream processes for PAT-SC1. The programme is expected to be complete by July 2011, at which time PAT-SC1 will be ready for a clinical trial production program.

PAT-SC1 is a natural human antibody that acts by binding to a special form of a protein, called CD55 that appears on the surface of gastric cancer cells but not on the surface of healthy cells, thereby permitting PAT-SC1 to kill the cancer cells while sparing the healthy cells. PAT-SC1 was evaluated in an investigator led human clinical trial, under which treated patients were dosed with PAT-SC1 48 hours prior to a surgical procedure that involved the removal of the primary tumour (surgical removal of the tumour is currently the standard treatment). Thirty-five PAT-SC1 treated gastric cancer patients showed a statistically significant increased survival benefit compared to a historic control group of 53 patients that received the same surgical treatment but who did not receive PAT-SC1.

Gastric cancer can develop in any part of the stomach and may spread throughout the stomach and to other organs; particularly the esophagus, lungs, lymph nodes, and the liver.