With plans to target the ballooning obesity market, Gelesis Inc. raised $16 million in its Series A financing.

The Boston-based company has remained under the radar since its founding in 2006, and Eric Elenko, interim vice president of business development, declined to comment on its technology or pipeline.

Yet Gelesis's patents may provide a clue to its obesity approach. The company has intellectual property relating to synthetic polymers that swell in the stomach to create a feeling of "fullness."

Another clue might be gleaned from that fact that Gelesis was co-founded by Exotech Bio Solutions, an Israeli chemistry company that has developed a biodegradable, superabsorbent polymer called ExoSAP.

Whatever Gelesis is up to, the company has managed to attract an impressive roster of scientific advisors. SAB members include Elazer Edelman, of Harvard University; former FDA executive David Feigal; gastric balloon pioneer Allan Geliebter; James Hill, of the University of Colorado; Lee Kaplan, of Massachusetts General Hospital Weight Center; and Stephen Woods, of the University of Cincinnati's Obesity Research Center.

The current financing also attracted new lead investor OrbiMed Advisors, new investor Queensland BioCapital Funds Pty Ltd. and existing investor PureTech Ventures. PureTech previously had co-founded Gelesis and, along with its partners, provided $900,000 in seed funding. Gelesis also previously received a $1 million grant from the BIRD (Israel-U.S. Binational Industrial Research and Development) Foundation, which supports technology partnerships between Israeli and American companies.

Elenko said proceeds from the Series A financing would be used to drive Gelesis's mysterious product "into appropriate clinical trials."

The obesity field is bursting with clinical trials, including Phase III programs for Orexigen Therapeutics Inc.'s Contrave (bupropion and naltrexone), Vivus Inc.'s Qnexa (phentermine and topiramate) and Arena Pharmaceuticals Inc.'s lorcaserin hydrochloride, as well as several late-stage big pharma programs and a host of early- and mid-stage biotech trials.

Marketed obesity drugs in the U.S. include Xenical (orlistat, F. Hoffmann-La Roche Ltd.), Meridia (sibutramine HCl monohydrate capsules C-IV, Abbott) and nonprescription Alli (low-dose orlistat, GlaxoSmithKline plc).

As a result of the financing, OrbiMed's Jonathan Silverstein and Rishi Gupta were named to Gelesis's board of directors. Other BOD members include Gelesis co-founder and CEO Yishai Zohar, Gelesis co-founder Mendy Axlerad, PureTech partner Ronald Cape, former U.S. CEO of Schwarz Pharma AG Klaus Veitinger, and Epix Pharmaceuticals Inc. chief business officer Chen Schor.

In other financing news:

• Calistoga Pharmaceuticals Inc., of Seattle, completed its $26.2 million Series A financing, adding $5.2 million of new money to the $21 million raised last March. Existing investors in the round - which included Frazier Healthcare Ventures, Alta Partners, Three Arch Partners and Amgen Ventures - agreed to pony up and accelerate the additional funds. The money will allow Calistoga to advance two small-molecule, phosphoinositide-3 kinase (PI3K) inhibitors into multiple clinical trials for cancer and inflammation. (See BioWorld Today, March 6, 2007.)

• Merrion Pharmaceuticals Ltd., of Dublin, Ireland, withdrew its proposed initial public offering, citing unfavorable market conditions. The company originally had filed to sell 4 million American depository shares priced between $10 and $12 per ADS, but it later lowered the range to between $6 and $7 per ADS. Merrion, which has oncology programs in Phase II and Phase III trials, had applied to list its shares on Nasdaq under the ticker "MERR" and on the Irish Enterprise Exchange under the ticker "3MP." (See BioWorld Today, April 3, 2007.)

• OSI Pharmaceuticals Inc., of Melville, N.Y., plans to offer $150 million worth of unsecured, convertible senior subordinated notes due 2038. Investors also will have a 13-day option to purchase an additional $22.5 million worth of notes. The notes will convert into OSI common stock at a price to be determined. Approximately 30 percent of the proceeds will be used to repurchase OSI's common stock, with the remainder used to repurchase or retire 3.25 percent convertible senior subordinated notes due 2023, or for general corporate purposes.

• Rexahn Pharmaceuticals Inc., of Rockville, Md., raised $6.8 million through the private placement of stock and warrants. The company expects to raise an additional $1.8 million by the end of February. Proceeds will be used for general corporate purposes, including ongoing Phase II cancer trials with the antisense oligonucleotide Archexin and planned Phase II trials with the dual serotonin and dopamine modulators Serdaxin for depression and Zoraxel for male sexual dysfunction.

• Tempo Pharmaceuticals Inc., of Cambridge, Mass., closed an $8.1 million Series B financing round. New investors Bessemer Venture Partners and Alexandria Real Estate Equities joined existing investors Polaris Venture Partners, Venrock Associates, Lux Capital and William Rastetter, former executive chairman of Biogen Idec Inc. and a partner at Venrock. Proceeds will be used to continue the preclinical development of Tempo's Nanocell technology, which combines two drugs that need different release rates - such as chemotherapy and an anti-angiogenesis agent - into a nanoparticle. Tempo closed a $12.1 million Series A financing in May. (See BioWorld Today, June 18, 2007.)