TopoTarget Stock Surges on Trickle of Data for Belinostat
By Cormac Sheridan
Without revealing much in the way of new data, TopoTarget A/S enjoyed a 45 percent bounce in its share price during early trading Tuesday, as an analysis of the final top-line results from a registration trial of belinostat in patients with relapsed or refractory peripheral T-cell lymphoma (PTCL) confirmed the drug exceeded the efficacy level defined by the study's primary endpoint, a minimum objective response rate (ORR) of 20 percent.
The threshold had been agreed on with the FDA under the agency's special protocol assessment process. Copenhagen, Denmark-based TopoTarget and U.S. partner, Spectrum Pharmaceuticals Inc., disclosed in September that belinostat, a pan-histone deacetylase (HDAC) inhibitor, already achieved the objective. (See BioWorld Today, Sept. 24, 2012.)
TopoTarget CEO Anders Vadsholt said the final ORR calculation put the drug on par with the two drugs already approved in that indication, the HDAC inhibitor Istodax (romidepsin) and the dihydrofolate reductase inhibitor Folotyn (pralatrexate), which are marketed, respectively, by Summit, N.J.-based Celgene Corp. and by Spectrum. That pushes belinostat's ORR into the 25 percent to 27 percent range.
That level of efficacy, in a highly refractory population, combined with the drug's favorable safety profile – data were disclosed in January at the T-Cell Lymphoma Forum in San Francisco – further strengthens the drug's commercial credentials, albeit in an indication with a limited patient population. "Our safety profile looks very, very good compared to the others," Jette Tjornelund, head of clinical pharmacology at TopoTarget, told a conference call audience.
It also strengthens the likelihood of TopoTarget getting a nice payday in the not-too-distant future. Henderson, Nev.-based Spectrum gained the rights to commercialize the product in North America and India in a 2010 deal worth up to $350 million in up-front and milestone payments, plus 1 million Spectrum shares and midteen-percentage sales royalties.
The stock (NASDAQ:SPPI), which closed at $11.49 Monday, is payable on an FDA acceptance for review of the belinostat new drug application, along with a $10 million cash milestone. That could come as soon as the third quarter, as Spectrum is expected to file for approval before the end of June. TopoTarget also would receive another $20 million upon FDA approval. Given the drug's fast-track designation, that could follow in early 2014.
The open-label trial, dubbed BELIEF, recruited 129 patients, a handful of whom remain in treatment. The company has yet to release data on secondary endpoints, which include time to response, duration of response, time to progression, progression-free survival (PFS), one-year PFS, one-year overall survival and overall survival. Final data have been submitted for presentation at American Society of Clinical Oncology meeting, which this year runs from May 31 through June 4 in Chicago.
Further trials appear necessary for the drug to achieve its full potential, however. Part of its appeal in PTCL is its lack of bone marrow toxicity, which would allow it to be administered in chemotherapy regimens. "You definitely have to do confirmatory studies to confirm it," Vadsholt told BioWorld International.
Additional studies most likely also would be required for a European approval. The European Medicines Agency already rejected applications for Istodax and Folotyn as they were based on open-label trials. "That also we expect would be the case for TopoTarget," Vadsholt said.
The company is considering its options about how best to take the drug forward in Europe and elsewhere. Several other countries may approve the drug based on the trial data that will be submitted to the FDA, Vadsholt said. Compassionate use may be permitted in Europe in the absence of a marketing authorization.
Shares of TopoTarget (COPENHAGEN:TOPO) reached as high as DKK2.69 (US47 cents) during trading Tuesday before shedding some of those gains in the afternoon. The stock closed at DKK2.45, up 32.4 percent on Monday's close.
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