HENDERSON, Nev. ( TheStreet) -- Spectrum Pharmaceuticals ( SPPI - Get Report) and TopoTarget are collaborating on the development of the lymphoma drug belinostat, but the partners aren't on the same page over the outcome a pivotal study -- yet. On Friday morning, TopoTarget, a Danish drug firm, announced that the primary endpoint had been meet for the belinostat phase II trial for patients with peripheral T-cell lymphoma (PTCL). Spectrum, however, chose not to participate in TopoTarget's announcement. Instead, Spectrum filed an 8-K Friday evening, characterizing the belinostat study results as "preliminary" and said a definitive verdict wouldn't be determined until final data are collected and analyzed at the end of the fourth quarter. "Our conservatism makes us more cautious than TopoTarget," said Shiv Kapoor, Spectrum's vice president for strategic planning and investor relations, in an email. "Although we are more optimistic about the final results of the trial, we want to wait until final results to confirm whether we met the
primary endpoint or not." Spectrum shares rose 22 cents to $12.51 in Friday trading. TopoTarget conducted the belinostat study but Spectrum controls commercial rights to the lymphoma drug in North America and will be in charge of seeking regulatory approval in the U.S. Belinostat is one of two cancer drugs in Spectrum's late-stage pipeline, the other being the bladder cancer drug apaziquone. But belinostat took on added importance to the company in April because apaziquone failed to delay tumor recurrence compared to placebo in two phase III studies. The pivotal phase II "BELIEF" study of belinostat -- conducted under a Special Protocol Assessment agreement with the FDA -- enrolled 129 patients with peripheral T-cell lymphoma (PTCL) that failed to respond to at least one prior therapy. All patients in the study are being treated with belinostat -- there is no control arm. TopoTarget said Friday that the primary endpoint of the BELIEF trial was reached because the tumors of at least 20% of patients shrank following treatment with belinostat. A precise belinostat response rate was not disclosed Friday, nor was the duration of response.
Since belinostat is not being compared to any other treatment, FDA also considers duration of response to be an important measure of drug efficacy. Celgene's ( CELG - Get Report) Istodax, which, like belinostat, is an HDAC inhibitor, was approved for patients with advanced PTCL in June 2011 on the basis of a single-arm study with an overall response rate of 26% and a median duration of response of 12 months. Spectrum's Folotyn -- just acquired from Allos Therapeutics -- is also approved for PTCL with an overall response rate (per the drug's label) of 29% with a median duration of response of 10 months. The Folotyn pivotal study was also a single-arm design. "I am sure the FDA will want to look at the complete data picture," said Kapoor, referring to the final response rate and duration of response data from the belinostat study. Spectrum will bring the final belinostat data to a meeting with FDA officials before filing for approval, possibly in 2013, the company said. --Written by Adam Feuerstein in Boston. >To contact the writer of this article, click here: Adam Feuerstein. >To follow the writer on Twitter, go to http://twitter.com/adamfeuerstein. >To submit a news tip, send an email to: email@example.com. Follow TheStreet on Twitter and become a fan on Facebook.