Ovarian cancer trial shows positive results

Kazia Therapeutics, an Australian oncology-focused biotechnology company, attended the American Association of Cancer Research (AACR) Annual Meeting earlier this month. There, the company released a poster presentation summarising data from Part A of its ongoing phase I study of Cantrixil (TRX-E-002-1) in ovarian cancer — a study which has so far seen promising results.

Ovarian cancer is diagnosed in approximately 240,000 women each year worldwide and is the eighth most common cause of cancer death in women. The five-year survival rate remains low, at approximately 45%, reflecting the fact that the disease is often advanced at the time of diagnosis.

The phase I study of Cantrixil commenced in December 2016 and is structured in two parts: Part A aimed to understand the safety profile of Cantrixil and to establish the maximum tolerated dose (MTD), while Part B (ongoing) will recruit 12 patients at the MTD to seek preliminary signals of efficacy. Following the recent opening of an additional site, the study is currently being conducted at six hospitals in the United States and Australia.

The study protocol was designed such that patients received two cycles (six weeks) of therapy with Cantrixil alone, followed by up to six cycles (18 weeks) of Cantrixil administered in combination with standard-of-care chemotherapy. Nine patients enrolled in the study completed the first cycle of treatment with Cantrixil, making them evaluable for determination of the MTD.

The study enrolled patients at doses ranging from 0.24 to 20 mg/kg, with 5 mg/kg determined to be the maximum tolerated dose. This is within the therapeutic range that would be predicted from preclinical data. The main adverse events were gastrointestinal in nature, and included abdominal pain, ileus and bowel obstruction. Diarrhoea, nausea and vomiting were also seen, but were not generally dose-limiting.

All patients had recurrent or persistent ovarian cancer and had failed at least two prior lines of therapy, prior to study entry, representing a very advanced population. After two cycles of treatment with Cantrixil, five of nine evaluable patients (56%) achieved stable disease, according to the industry-standard RECIST criteria, which means that the tumour remained approximately the same size over time and had not progressed. One of these patients subsequently achieved a partial response when Cantrixil was administered with standard-of-care chemotherapy, which means that the tumour was reduced in size by 30% or more.

Four out of nine patients (44%) remained on the study drug for the entire 24-week duration of the study (approximately six months), without experiencing progression of their disease. For comparison, data from other studies in a similar patient group has found a progression-free survival of approximately 3.4 to 4.7 months. This further suggests the possibility that Cantrixil may help to delay disease progression.

“The data from this study shows that Cantrixil has a safety profile very suitable for further development, and we have been able to reach a dose well within the predicted therapeutic range,” said Kazia Therapeutics CEO Dr James Garner. “It is extremely positive that we have seen some preliminary evidence of efficacy at this early stage in development, and the ongoing Part B of the study should give us much more information.”

Kazia expects to report initial data from Part B of the study in the second half of 2019.

Image credit: ©stock.adobe.com/au/nerthuz

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