Staff Writer

Aton Pharma Inc. completed an equity financing worth $13.7 million, the third and final tranche of a Series A round.

Open for more than a year and a half - since the company's April 2001 inception - the financing raised $48.7 million in total. Earlier tranches included $15 million at the company's founding and $20 million in February, Emma Reeve, Aton's newly appointed chief financial officer, told BioWorld Today.

She labeled the company's work in developing small-molecule inhibitors of chromatin-modifying enzymes as a source of investor interest. To date, the Tarrytown, N.Y.-based company has advanced a pair of programs into clinical trials.

The privately held firm said its primary plans for the funds include continued development of its lead clinical candidate, suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor in Phase II cancer trials.

"This financing will take us through Phase II," Reeve said. "Our lead compound and some backup compounds are in an area called chromatin science. There's been a lot of interest in this area."

Aton in late October began a single-agent Phase II study of SAHA in cutaneous T-cell lymphoma and peripheral T-cell lymphoma. An additional single-agent Phase II study in patients with recurrent or metastatic squamous cell cancer of the head and neck also is under way. Patient accrual continues for the studies, both of which use oral formulations.

Phase I studies of oral and intravenous formulations found evidence of antitumor activity, pushing SAHA's development in the cancer direction.

"That was pretty exciting, because we weren't necessarily looking for that," said Reeve, who most recently served as assistant controller at New York-based Bristol-Myers Squibb Co.

While it is too early to have Phase II results in hand, Aton said Phase I results on SAHA, which were presented at the Molecular Targets and Cancer Therapeutics conference in Frankfurt, Germany, demonstrated it is readily bioavailable and results in prolongation of acetylated histone accumulation in peripheral blood mononuclear cells, compared to an identical dose administered intravenously. Aton conducted the trial in patients with refractory solid tumors, lymphomas and leukemias in collaboration with investigators at Memorial Sloan-Kettering Cancer Center in New York.

Additional Phase II trials of the orally formulated drug will study it as a single agent and in combination with other cancer therapies.

Aton said it also will apply its latest funding to develop other histone deacetylase inhibitors in its pipeline and expand its chromatin science-based discovery programs.

"We have backup compounds that we're continuing to develop, and a discovery program behind that," Reeve said.

Another of its histone deacetylase inhibitors, pyroxamide, also is in a cancer clinical trial. An intravenous formulation of the small molecule was advanced into Phase I, based on its ability to suppress tumor growth in preclinical work.

Aton expects to continue its discovery and development efforts beyond cancer, as well.

"There's a lot of interest in these histone deacetylase inhibitors, particularly, for example, in neurodegenerative disorders," Reeve said. "We're looking at pursuing further cancer applications and in other areas with unmet medical needs."

Specifically, she pointed to an interest in developing SAHA to treat Huntington's disease.

The 35-person company has yet to partner any of its compounds, though Reeve said Aton hopes to enter a partnership in about the next 12 months. Its growth, which stemmed from research at Memorial Sloan-Kettering and Columbia University, nonetheless is continuing with recent executive management hires, including Reeve.

The financing included new investors Perseus-Soros Biopharmaceutical Fund, of New York, and The Wellcome Trust, of London, as well as previous investors. Concurrent with the financing, Aton appointed to its board Dennis Purcell, the senior managing partner at Perseus-Soros.