Disclosing final data from the pivotal Phase II/III trial with its anticancer drug Onco TCS, Inex Pharmaceuticals Corp. said the outcome reinforces good news suggested by the first look at results in December.
"There's been no material change and the numbers even have gone up a little bit," said David Main, president and CEO of Vancouver, British Colombia-based Inex, which tested the product in 119 patients with relapsed aggressive non-Hodgkin's lymphoma.
"We'll be filing our [new drug application with the FDA] toward the end of the third quarter or early in the fourth," Main told BioWorld Today, repeating earlier guidance.
Inex's stock (TSE:IEX) closed Wednesday at C$5.95, up 65 cents, or 12.26 percent.
Onco TCS is made of the widely used off-patent cancer drug vincristine encapsulated in INEX's TCS liposomal drug delivery technology, designed to provide longer blood circulation, tumor accumulation and extended drug release at the cancer site. Inex plans to develop it for use as a stand-alone drug or in combination therapy in several cancers against which vincristine is deployed.
Main said the company is "in the thick of discussions" with potential partners. In the spring, Inex regained full ownership of Onco TCS from Dublin, Ireland-based Elan Corp plc., which said it was withdrawing from oncology. (See BioWorld Today, April 4, 2003, and Aug. 12, 2002.)
Inex previously had offered results from the first 102 NHL patients, who showed an overall response rate of 24 percent, an outcome that didn't please the market, which responded by knocking down Inex's stock by about one-third. Shares closed that day at C$5.35. (See BioWorld Today, Dec. 4, 2002.)
A Phase I/II trial had garnered a 44 percent response rate, but the patient pool was not like the population tested in the Phase II/III trial - a subset of which was similar and showed a 50 percent response rate, noted analyst Brian Bapty with Raymond James Ltd. in Vancouver, in December. Disclosing the partial Phase II/III data at the time, Inex also moved its estimate for the NDA filing from the first quarter to the third quarter of this year.
In the Phase II/III trial, patients had failed, on average, four previous treatment regimens, including vincristine. Complete results show an overall response rate near that indicated by the first data (25 percent), including seven patients whose tumors were completely eliminated and 23 whose tumor volume was reduced by more than 50 percent. Another 31 patients had their disease stabilized while undergoing treatment.
"There's no standard of care in this relapsed population," Main said, and the disease progresses quickly. "The average survival is typically less than one year."
The median duration of response for the 30 responding patients was about three months from first documentation by a computed tomography scan, typically taken about two months after treatment begins. Duration of response for some patients went beyond six months, Main noted, and the drug was well tolerated.
Getting the drug to the tumor site while not affecting healthy cells is a challenge met particularly well by Onco TCS's delivery route, Main added.
"The problem is, at this point, the patients don't want to be subjected to more toxicity," he said, especially since they often are elderly. The median age of the patients in the pivotal trial was 60.
Inex is developing other drugs using the TCS technology but "we don't refer to ourselves as a drug delivery company," Main said. "We use it as a competitive advantage to create products we own and control."
If approved, Onco TCS could follow the likes of Iressa and Velcade, both granted marketing clearance based on small, uncontrolled, single-arm trials in patient populations with critical needs.
Iressa (gefitinib) is London-based AstraZeneca plc's epidermal growth factor tyrosine kinase inhibitor pill for advanced non-small-cell lung cancer. Velcade (bortezomib) is the proteasome inhibitor for multiple myeloma from Millennium Pharmaceuticals Inc., of Cambridge, Mass. Both were approved in May.