Cell Therapeutics shows good results with Xyotax

Scientists from Cell Therapeutics have reported encouraging data from a phase I study of escalating doses of Xyotax in combination with cisplatin for the treatment of patients with solid tumors.

The primary objectives of the trial were to determine the maximum tolerated dose of Xyotax in combination with cisplatin and to determine the overall safety of this regimen. Xyotax, being developed by Cell Therapeutics, is a pharmaceutical that links paclitaxel to a biodegradable polyglutamate polymer. In the study Xyotax was administered at paclitaxel doses equal to or higher than the approved dose of Taxol.

Eleven of 13 evaluable patients (85%) achieved durable disease control, with five patients (38%) achieving a partial remission (PR) and six patients (46%) with stable disease. Of the five ovarian cancer patients in the study, all experienced disease control and significant declines in CA-125, a tumor marker, levels with three of the five (60%) achieving a PR. All four ovarian cancer patients with platinum-resistant disease achieved disease control.

Partial remissions were also reported in patients with tumours generally not expected to respond to taxanes, including mesothelioma and schwannoma. Combination therapy, even at Xyotax doses of 225mg/m² (paclitaxel equivalent dose) was well tolerated with some patients receiving as many as 12 cycles (40 weeks) of therapy. Side effects observed were consistent with cisplatin therapy and included grade 4 neutropenia in nine patients, with one case of febrile neutropenia reported. Reversible grade 3 neuropathy was reported in one patient after seven cycles.

'These interim clinical data continue to suggest that Xyotax in combination with cisplatin is a well-tolerated regimen with significant anti-tumour activity even in platinum-resistant and taxane-resistant tumours,' said Dr Jack W. Singer, research chair of CT. 'The data showing that all five ovarian cancer patients in the study have achieved durable disease control despite having failed multiple other treatment regimens is particularly impressive and supports the decision of the prestigious gynecologic oncology group to conduct a phase III study of Xyotax in the treatment of front-line ovarian cancer.'

'This multicenter, open label phase I study was designed to assess the maximum tolerated dose, dose-limiting toxicities, and overall safety of combining cisplatin with Xyotax. In the study, 16 patients with various tumours received cisplatin and escalating doses of Xyotax administered every three weeks for up to 12 cycles of treatment. The study will continue with Xyotax (250mg/m²) and cisplatin (75mg/m²).