New Zealand patients trial local cancer drug (2012)

PR610 is the first in a new class of cancer “stealth drugs”, invented by Dr Jeff Smaill and Associate Professor Adam Patterson from the Auckland Cancer Society Research Centre and Maurice Wilkins Centre.

“We’ve designed a remarkable molecule with substantial anti-tumour activity,” Jeff says. “The rapid pace with which this novel treatment has reached the clinic is a tribute to the efforts of a talented drug development team.”

The scientists have cleverly exploited an abnormality of tumours to make a drug that can tell the difference between cancer and healthy tissue, potentially minimising the side effects of treatment.

Administered in an inactive form, PR610 transforms into a powerful cancer drug only in the abnormally low-oxygen conditions found in most solid tumours. Once active it permanently inhibits key receptors in cancer cells. It is designed to achieve high, active doses in tumours while remaining dormant in healthy tissues, avoiding the collateral damage associated with standard chemotherapies. This is an entirely new treatment approach.

The first clinical trial of PR610 began in late 2012 at Auckland City Hospital, Waikato Hospital and sites in the United States.

“It’s especially pleasing to see clinical trials of new drugs being held in New Zealand,” says Mr John Loof, CEO of Cancer Society Auckland.  “Local patients can be some of the first involved in furthering our understanding of how these targeted medicines can make such a difference.”

The phase I/II study will investigate suitable doses in patients with a range of solid tumours, and then move on to monitor side effects, blood levels and anti-tumour activity in patients with non-small-cell lung cancer (NSCLC) that has become resistant to standard treatment.

Lung cancer is the leading cause of cancer death and NSCLC is the most common form. Currently there is no effective treatment for NSCLC, which has become resistant to standard chemotherapy. Initial development of PR610 will focus on patients with this disease, and subsequent studies will evaluate the drug in other cancers, such as gastric and breast cancer.

“PR610 had striking activity against cancer in the laboratory,” co-inventor Adam Patterson says. “When tested alongside other clinical candidates, it was the only agent capable of shrinking drug-resistant lung cancer. With Proacta’s expert support, the US Food and Drug Administration approved an Investigational New Drug Application for PR610, allowing the drug to progress to human trials.”

PR610 is part of a pipeline of hypoxia-activated kinase inhibitors from Adam and Jeff’s groups licensed to biotechnology company Proacta Incorporated (a New Zealand-founded company now based in San Diego). Proacta has an agreement with Yakult Honsha Co., Ltd, for research, development and commercialisation of PR610 in Japan.

Image: Initial development of New Zealand-designed “stealth drug” PR610 is focusing on patients with non-small cell lung cancer – the most common form of lung cancer. Image: © Sebastian Kaulitzki | Dreamstime.com