Development of Cell Therapeutics/Novartis' gender-specific lung cancer candidate Xyotax (paclitaxel poliglumex) has been delayed by at least six months to amend the PIONEER study's protocol. The firms have also temporarily suspended study enrollment to assess differences in early cycle deaths observed between the trial arms.

CTI announced Nov. 3 suspension of the trial following consultation with the Phase III study's data safety monitoring board, while the company awaits follow-up data of recently enrolled patients.

"CTI agreed to suspend enrollment on the trial to allow maturity of the data and assessment of differences in early cycle deaths observed between arms of the study," the company reported. While most of the deaths were attributed to disease progression, the firm said more complete data is required to analyze the difference.

Patients currently enrolled in the trial will continue treatment. Xyotax is being studied for the treatment of advanced-stage non-small cell lung cancer.

In addition, CTI said it intends to amend the current study protocol while the trial is suspended. PIONEER will be amended to focus the primary efficacy endpoint on survival in women with normal estrogen levels - representing the subset of patients demonstrating the greatest survival benefit in the earlier STELLAR trials.

"Given that only approximately one-half of patients sampled have normal estrogen levels in the PIONEER trial compared to approximately two-thirds of patients for which estrogen data was available in our prior STELLAR trials, we decided it would be prudent to amend the protocol," CTI said.

The firm plans to submit a special protocol assessment request that would delay the interim analysis at least six months.

CTI decided to develop Xyotax as a lung cancer treatment specifically for women, based on the results of two STELLAR trials. STELLAR 3 and 4 failed to meet the primary endpoint of superior survival benefit in the overall patient population, but did show a benefit in women (¹ Also see "Cell Therapeutics Will Pursue Xyotax Approval For Women With NSCLC" - Pink Sheet, 24 August, 2005.).

As a result, the company decided to pursue development of Xyotax in women and initiated PIONEER, a 600-patient confirmatory trial. CTI previously said it could potentially submit an NDA for Xyotax based on the interim results of the study in July or August 2007 (² Also see "Cell Therapeutics Expects 2007 NDA Filing For Xyotax" - Pink Sheet, 1 June, 2006.).

In September, Novartis signed a licensing agreement with Seattle-based CTI, offering up to $270 mil. in product registration and sales milestones for Xyotax, in addition to making a $15 mil. equity investment in the company (³ Also see "Novartis Signs Development Deal With Cell Therapeutics For Xyotax" - Pink Sheet, 18 September, 2006.).

-Jessica Merrill (j.merrill@elsevier.com)

Novartis And Cell Therapeutics Suspend Xyotax Development

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