After quietly incubating for a year under the tutelage of co-investors Third Rock Ventures LLC and Atlas Venture, Magenta Therapeutics burst onto the cell therapy scene with a $48.5 million A round to advance its goal of transforming stem cell transplantation for patients with autoimmune diseases, genetic blood disorders and cancer.

Third Rock and Atlas led the round, joined by GV (formerly Google Ventures), Access Industries (Blavatnik Group) and Partners Innovation Fund.

Magenta, of Cambridge, Mass., boasted of the first "complete" platform to address critical challenges in stem cell transplant by focusing on three key areas to transform the process: targeted therapeutics for patient conditioning, rapid and efficient agents for stem cell harvesting and innovative methods to promote stem cell growth during culture in the laboratory.

"This is the first time a company has been created in stem cell transplant medicine to take a holistic, global view of the patient's journey, tackle the challenges that limit these transplants today and think broadly about how we can use this powerful medicine in many more patients and many more diseases," Jason Gardner, Magenta's CEO, president and co-founder, told BioWorld Today.

The company's story began, literally, on a run. A year ago, Gardner, at the time vice president and head of Glaxosmithkline plc's (GSK) R&D Satellite in Boston, joined Atlas Venture's running squad for a networking run around the Charles River. Gardner had completed a postdoctoral fellowship in hematopoietic stem cells at Harvard Medical School under David Scadden, professor of medicine, co-director of the Harvard Stem Cell Institute and chairman of the department of stem cell and regenerative biology, before embarking on various stem cell and regenerative medicine roles at GSK. As the run was starting, Atlas Partner Bruce Booth began quizzing Gardner on his views about stem cell transplants. The two continued to discuss the state of the science, the unmet medical need for patients and the elements needed to transform the field.

"Before I'd got my shower, Bruce had sent me an email and asked me to think about coming onboard at Atlas and helping to build a company in this area," Gardner recalled.

Gardner knew that interesting scientific ideas were "percolating" in the field. Through collaborations with Scadden while at GSK, he was aware of the latest breakthroughs in stem cell biology. Gardner also was aware that Alexis Borisy, a Third Rock partner who did his graduate work at Harvard in the lab of Stuart Schreiber, professor of chemistry and chemical biology, had taken a keen interest in stem cell transplant medicine. With the stars aligned, so to speak, Gardner left GSK, joined Atlas as an entrepreneur-in-residence and began working with both venture firms to weave together the threads of a company with a big vision and broad mission to transform the stem cell transplant field.

"It was an opportunity I couldn't resist," Gardner admitted.

'A LOT OF INTEREST FROM POTENTIAL PARTNERS'

Over the past nine months, Gardner and Magenta's start-up team – the company already has 20 employees, mostly scientists, and plans to double its head count by the end of next year – met with more than 100 experts in stem cell transplant to define the biggest obstacles to advancing the science and the areas of opportunity to extend the approach into diseases that were largely untapped.

Those conversations helped Magenta to define its three-pronged scientific approach. For starters, rather than conditioning patients with conventional radiation and/or chemotherapy, the company aims to develop targeted antibody conditioning that will result in safer and more efficient preparation for stem cell transplant while expanding the range of indications beyond oncology. The company already has accrued preclinical findings in this area.

For the second leg of the platform, the goal is to replace conventional harvesting of stem cells from bone marrow – a difficult surgical procedure performed under general anesthesia – with harvesting them from the patient's blood. The process involves treatment with growth factors to mobilize stem cells, which actually engraft the patient more quickly and reduce inpatient days. Magenta's scientists already discovered molecules that result in the robust mobilization of large numbers of stem cells, providing a readily available source of stem cells for more patients, Gardner said.

The third priority is to increase the number of stem cells, since science has shown that the greater the number of these cells, the more likely the chance of successful transplant. Company scientists discovered methods to expand a patient's stem cells ex vivo – a key hitch in the current stem cell transplant system – to result in more robust infusion designed to improve outcomes over conventional methods.

Magenta inked a license agreement with Harvard for access to a portfolio of stem cell technologies developed at Harvard, Mass General and Boston Children's Hospital. Once the moving parts were corralled, the series A – designed to take the company through multiple milestones over the next few years – came together quickly, according to Gardner. GV, Access and Partners had funded some of the underlying academic work and jumped at the opportunity to join the syndicate.

With an ambitious vision and a platform that could be aimed in any number of directions, Magenta is beginning to collaborate with external groups to follow the data and "take a science-driven approach," Gardner said. Therapeutic work is at the preclinical stage, and the company has not divulged a timetable for investigational new drug application filings. Such decisions are slated to occur "as we go along," Gardner said.

Oncology, where stem cell transplantation has the longest and most successful history, is the logical proving ground, he acknowledged.

The stem cell transplant process is less widely used in autoimmune disease, "but we think that's going to change in time," he added, suggesting that Magenta scientists are likely to "diverge" and work more closely with those groups, given the background of scientific co-founder Alan Tyndall, emeritus professor, head of rheumatology and co-founder of the Basel Stem Cell Network at the University of Basel.

Magenta has the pedigree to make good on its mission. In addition to Gardner, Scadden – who chairs the scientific advisory board – and Tyndall, other scientific co-founders include Derrick Rossi, associate professor of stem cell and regenerative biology at Harvard University, principal faculty member at the Harvard Stem Cell Institute and investigator in the program in cellular and molecular medicine at Boston Children's; John Dipersio, professor of medicine, pediatrics and pathology/immunology and chief in the division of oncology at Barnes Jewish Hospital's Siteman Cancer Center at Washington University St. Louis School of Medicine; Robert Negrin, professor of medicine, division chief of the blood and marrow transplant program and medical director of the clinical bone marrow transplantation laboratory at Stanford University; and Luigi Naldini, director of the San Raffaele-Telethon Institute for Gene Therapy in Milan.

Michael Cooke, Magenta's chief scientific officer, most recently served as executive director of immunology at the La Jolla research campus of Novartis AG, the big pharma where Bastiano Sanna, Magenta's chief operating officer, also was a member of the leadership team in the Cell and Gene Therapy Unit. Christina Isacson, a former business development executive at Ironwood Pharmaceuticals Inc. and principal at Third Rock, rounds out Magenta's executive team as vice president and head of business development.

Gardner, Booth and Borisy sit on the board of directors, which is led by Mike Bonney, former CEO of Cubist Pharmaceuticals Inc., as executive chairman, and includes Tom Daniel, former president of research and early development at Celgene Corp., as independent director.

The company's name refers to a color that does not exist in the visible spectrum, created instead as a mixture of red and blue. As a chimeric color, Magenta also harkens to the chimerism that occurs in a successful stem cell transplant when new and old immune systems co-exist.

Despite a "big, broad vision" with the intent to pursue global programs, "we're pretty humble" about moving the platform forward, Gardner maintained.

"Making drugs is hard," he said, adding that the company welcomes partners with complementary expertise. Magenta expects to develop a suite of products in each of its three core disciplines, "and there are certainly opportunities for potential partnerships along the way as those medicines are developed," Gardner said.

Deal flow might begin sooner rather than later.

"I would be remiss if I didn't mention that we had a lot of interest from potential partners even before the launch," Gardner confessed.