Calimmune Inc., a gene-therapy drug startup company co-founded by a University of Arizona alumnus, will be acquired by Australian-based biotech drug giant CSL Ltd. for $91 million.

The deal, which will make Calimmune part of Pennsylvania-based CSL Behring, also includes up to $325 million in potential performance based milestone payments over eight or more years after the transaction’s close, expected within the next two weeks.

Calimmune, co-founded by UA biology grad and entrepreneur Louis Breton in 2006, is developing stem-cell gene therapy to strengthen patients’ own immune systems.

The company’s technology is based on research by co-founder and Nobel Prize winner David Baltimore of the California Institute of Technology, Irvin Chen of UCLA and Inder M. Verma of the Salk Institute for Biological Studies.

Calimmune’s clinical and laboratory operations are based in Pasadena, California, and Sydney, Australia, while its corporate office is in Tucson.

In 2013, Calimmune won an $8.3 million grant from the California Institute for Regenerative Medicine to study its HIV drug. Its lead drug candidate is in Phase I/II clinical trials as a one-time treatment to prevent HIV progression to AIDS.

The acquisition will give CSL Behring Calimmune’s pre-clinical drug candidate, CAL-H, a stem-cell gene therapy for the treatment of sickle cell disease and blood disorders, complementing the company’s current product portfolio, CSL said.

The deal also includes two proprietary Calimmune technologies to select genetically modified stem cells and to produce viruses used to deliver gene therapy.

CSL Ltd. CEO Paul Perreault said the acquisition will boost his company’s growth in gene therapy, calling Calimmune’s accomplishments thus far “impressive.”

“While Calimmune is still in the early stages, we believe that our combined strengths have tremendous potential to change treatment paradigms, and most importantly, significantly improve the lives of our patients,” Perreault said in a news release.

Breton, Calimmune’s CEO, said CSL is an established global leader in protein-replacement therapies, with a track record of driving new treatments to the global marketplace.

“Together, we are well positioned to take our achievements to the next level,” Breton said.

In 2015, Calimmune completed a $15 million Series B financing round, led by a large pharmaceutical company.

Members of Tucson’s Desert Angels investment group also provided early private-equity funding for the company.

CSL is one of the biggest biotech drug companies in the world, with fiscal 2016 revenue of $6.1 billion.

About 40 percent of the company’s revenues come from immunoglobulin products used to treat immunodeficient patients, while it also markets products such as vaccines and antivenins and operates CSL plasma-collection centers.

Contact senior reporter David Wichner at or 573-4181. On Twitter: @dwichner

Senior reporter covering business and technology for the Arizona Daily Star/