Aiming for success in female sexual dysfunction (FSD) after hitting roadblocks with U.S. regulators in erectile dysfunction (ED), Palatin Technologies Inc. is drawing from the $20 million raised last week in equity, along with $10 million in debt, to launch a phase III, 550-patient study that will test bremelanotide (BMT) in an eight-month experiment with an open-label extension phase.
“We have a pretty good understanding of what it takes to get the right patients enrolled into these types of studies,” having screened more than 1,000 patients for the phase IIb trials in FSD and enrolled more than 400 in that effort, said Palatin CEO Carl Spana during a conference call on earnings in mid-November. The start of the phase III bid in the U.S. triggers a development milestone payment of €2.5 million (about US$3 million) from Palatin’s partner in Europe, Gedeon Richter plc, of Budapest, Hungary.
BMT, a synthetic peptide analog of alpha-melanocyte-stimulating hormone, is the lead compound to emerge from Palatin’s melanocortin receptor agonist program and will be investigated at about 80 sites taking part in the phase III study. First data likely will become available in mid-2016.
Cranbury, N.J.-based Palatin recently closed on a private placement of 2.05 million shares of its common stock and series C warrants to buy 24,949,325 shares. QVT Financial LP invested $10 million and another accredited investment fund bought the same amount.
In the summer of 2007, the company was hit hard by news that the planned pivotal trials with BMT in ED had met with disagreement from the FDA, which questioned both the safety and the overall efficacy results offered by the company. Gatekeepers said the compound’s risk/benefit ratio did not support moving into phase III, at least not as first-line therapy. The following month, co-developer King Pharmaceuticals Inc., of Bristol, Tenn., exited the 2004 deal, which could have meant as much as $250 million for Palatin. (See BioWorld Today, Aug. 16, 2004, and Aug. 31, 2007.)
Palatin and King had tested BMT in four phase II studies involving more than 1,300 patients, and data from the at-home trials showed that the drug performed comparably to PDE5 inhibitors, a class that includes Viagra (sildenafil citrate, Pfizer Inc.), Cialis (tadalafil, Eli Lilly and Co.) and Levitra (vardenafil, Glaxosmithkline plc). Results also showed efficacy in patients with severe ED and in those nonresponsive to Viagra. Up to 50 percent of ED patients treated with BMT were restored to a normal level of function. But the data weren’t good enough for the FDA, which Palatin said was “amenable” to proposals for different development pathways for BMT, such as a second-line therapy in men who fail to respond to marketed PDE5 drugs.
BMT is given subcutaneously for FSD. Palatin found that the treatment, when given as a single spray in one nostril – as it was in 2007 – apparently caused blood-pressure rises, so the company switched routes of administration in order to better control how much BMT ended up in the body and thus limit exposure.
ASTRAZENECA NEWS AHEAD
Other hurdles in FSD involve finding the appropriate patients to study and using the correct instruments to gather findings. Researchers need to “[make] sure that patients not only have, say for example, low desire, but that they also have distress associated with that low desire and that there is no logical cause for their dysfunction,” such as relationship difficulties or taking antidepressants, Spana said.
As for collecting data, Palatin will deploy diaries with 28-day recall to measure desire. The approach, along with other matters related to FSD drug development, was discussed during a recent two-day meeting with the FDA on the indication.
Piper Jaffray analyst Charles Duncan wrote in a Nov. 18 research report that the FDA feedback and Gedeon partnership “bode well” for Palatin, which is working with its overseas partner to finalize the European phase III trial, forecast to start in the second half of next year. Duncan maintained an “overweight” rating on Palatin stock, with a price target of $4. Shares (AMEX:PTN) closed Monday at 79 cents, up 7 cents, or 9.7 percent.
Roth Capital Partners analyst Joseph Pantginis also was “encouraged” by the advancements made by the firm in FSD, and wrote in a research report the same day as Duncan’s that Palatin “represents a significant value proposition based on the promise of BMT in FSD, a large unmet medical need; increased partnering potential; important validation in hand with a large partnership with Astrazeneca [plc] for obesity; and strong pipeline growth potential.” Pantginis rated the stock at “buy” with a 12-month price target of $6.
The deal with London-based Astrazeneca, signed in 2007, was the second major collaboration involving melanocortin receptors for Palatin and promises as much as $310 million in the bid to develop small-molecule compounds for obesity and other metabolic disorders.
Spana said Palatin has “made excellent progress” and has identified “multi-potential lead clinical candidates. We continue to work with Astrazeneca to determine the best path forward.” Steve Wills, Palatin’s chief financial officer, said the next steps with Astrazeneca should be clear soon. “I would think that you’ll see something probably early in the new year,” he said. “We have discussions ongoing with them now.” (See BioWorld Today, Feb. 1, 2007.)