Assistant Managing Editor

The number "31" seems a lucky one for Tobira Therapeutics Inc. The 2006 start-up, which launched operations with a $31 million Series A, hauled in another $31 million in a Series B financing led by new investor Novo A/S.

"It's a tough economy out there," acknowledged James Sapirstein, president and CEO of the Manalapan, N.J.-based firm, but Novo "really liked our story."

Novo was joined by existing investors Domain Associates LLC, Frazier Healthcare Ventures, Montreux Equity Partners and Canaan Partners, who opted to add to their initial 2007 investments. (See BioWorld Today, Aug. 3, 2007.)

The company's primary draw is lead program TBR-652, a dual CCR5/CCR2 antagonist that could offer competitive advantages over Pfizer Inc.'s marketed HIV drug Selzentry (maraviroc). Tobira reported solid Phase IIa data this summer at the International AIDS Society meeting in Vienna, Austria, showing that the drug produced a median nadir decline from baseline in HIV viral load of up to 1.8 log10 copies/mL, with no serious adverse events reported.

But it's the drug's potential for adding anti-inflammatory benefits that could offer its biggest marketing edge.

Most HIV patients are able to control their disease fairly well with existing regimens, and often end up dying due to metabolic-related diseases, including cardiovascular disease and diabetes, which have an inflammatory basis. So being able to provide an anti-inflammatory benefit is the "future of HIV therapy," Sapirstein told BioWorld Today.

An upcoming Phase IIb study, slated to start in the first quarter of next year, is expected to include a substudy "to highlight an anti-inflammatory effect if there is one," he said.

Another advantage for TBR-652 is that it doesn't need a boost by ritonavir-like protease inhibitors. And it's a "true once-a-day drug," Sapirstein added, which would make it "a better choice for fixed-dose combos in the future."

The recommended dose for Pfizer's Selzentry is twice daily.

Approved in 2007, Selzentry sales got off to a slower-than-expected start, pulling in only $49 million in its first full year on the market, with some critics blaming the drug's high cost, as well as the high cost of the Trofile phenotypic companion diagnostic from Monogram Biosciences Inc. (now part of LabCorp.) to screen HIV patients for CCR5-tropic disease.

Like Pfizer, Tobira will need to screen patients for CCR5. The good news is that the agency is "open to entertaining the use of genotype testing" as well as phenotype testing, Sapirstein said. Genotype testing is far less expensive, he added, and, if the FDA gives its blessing, that would "a great opportunity for us."

Tobira still awaits final FDA approval for the Phase IIb protocol, but the firm is expecting to test TBR-652 in combination with the current standard of care, including Gilead Sciences Inc.'s Truvada (emtricitabine/tenofovir disoproxil fumarate).

But Sapirstein sees potential for TBR-652 in combination with other HIV drugs as well, including integrase inhibitors and even protease inhibitors.

Following the completion of the Phase IIb study, expected by the end of 2012, Tobira should be in position to seek a partnership. Meanwhile, funds from the Series B round are expected to carry the firm through 2013, Sapirstein said. "That's our goal."

The company has been careful in its spending to date. "When we raised the Series A, we said that would last until early 2009, but we were able to get into 2010," he added.