Oxigene's positive PhII ovarian cancer data faces analyst's skepticism

Shares of South San Francisco-based Oxigene ($OXGN) slumped this morning, dropping 10% in the wake of its analysis of a Phase II study of its experimental therapy for tough-to-treat cases of ovarian cancer. The data for fosbretabulin overall were positive, putting the company on the road to a pivotal Phase III study. But an analysis from Adam Feuerstein at TheStreet may have taken the wind out of its sails.

First, the numbers:

Investigators say that they tracked promising results in the midstage study, which recruited 107 patients with platinum-sensitive as well as platinum-resistant ovarian cancer. Combined with Avastin, the drug achieved a median progress-free survival rate--where the disease did not worsen--of 7.3 months compared to 4.8 months for Avastin alone. In a post hoc subgroup analysis involving 27 platinum-resistant patients (the toughest ones to treat) there was an even better outcome: 6.7 months of PFS versus 3.4 months in the Avastin-only arm.

Dai Chaplin

"We believe that these compelling data show fosbretabulin has a meaningful benefit in recurrent ovarian cancer, particularly in platinum-resistant patients who have extremely limited treatment options," said Dai Chaplin, Oxigene's president and CEO. "We now look forward to discussing these findings with the regulatory agencies to determine a potential path forward for fosbretabulin in ovarian cancer."

Here's where it ran into trouble, notes Feuerstein, an analyst who's done a considerable amount of work in the cancer field. A decision on using Avastin for ovarian cancer is looming, but hasn't arrived yet--complicating any analysis of a combination drug study like this. Avastin, by the way, achieved a solid PFS but not a statistically significant overall survival benefit for ovarian cancer patients, which may not prevent its approval.

If Avastin plus chemo becomes the standard of care in this area, then Oxigene will face some big challenges in designing a Phase III trial, notes Feuerstein. If the biotech decides to run a non-inferiority study, it will need a big and expensive patient population to examine. If it tries to beat Avastin/chemo, it faces a very tall order. And if Avastin is rejected, that makes Oxigene's task even more difficult.

Perhaps, suggests Feuerstein, the company should go a different route and try a combination with Votrient.

Investors, looking at the complications, evidently didn't see any easy answers this morning. And with its share price down today, Oxigene's execs will be challenged to provide some answers.

- here's the release from Oxigene
- here's the analysis from TheStreet

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