Baxalta R&D head John Orloff

Baxalta won't formally debut as an independent Baxter drug spinoff for a few more days, but the company isn't waiting to discuss an early peek at efficacy results from a Phase I/II study of their long-term gene therapy for hemophilia.

Investigators for Baxalta ($BAX)--which is setting up an R&D hub in Cambridge, MA--say they have recorded some initial responses from 7 patients in their dose-escalation study of BAX 335 for hemophilia B, including a setback in the small group receiving the highest dose.

Patients who run the risk of life-threatening bleeds can't naturally produce clotting factor IX. But Baxalta and a group of rivals that includes Biogen ($BIIB) and some of the new gene therapy startups--such as the Pfizer ($PFE)-partnered Spark Therapeutics ($ONCE) as well as Dimension Therapeutics--have been pushing ahead with gene therapies that promise to correct that error.

In Baxalta's case, it's getting the gene therapy tech that Baxter picked up from Chatham Therapeutics, nabbed in a buyout deal last year which included a $70 million upfront. Their gene therapy used a variant of factor IX, or FIX, called Padua, which is designed to specifically allow for lower doses to help improve the treatment's safety profile.

Investigators say they have spotted some clear patient responses. None have developed FIX inhibitors, while "some" FIX expression was seen in the lowest dose. At the midstage cohort level, two patients were bleed-free without regular infusions of factor IX while one had sustained FIX expression of 20% to 25% over 12 months.

At the highest dose, patients experienced the highest expression levels, but the treatment triggered an immune response that subsequently cut down on the expression. One patient was forced to resume infusions after peak expression levels crossed the 50% level at one point.

It's early days in this particular development race, but a full slate of large and small biotechs believe that they have an inside track in developing durable therapies for hemophilia, if not outright cures. For Baxalta and Biogen, these programs could be key to defending major markets.

''Gene therapy has the potential to achieve a long term therapeutic solution for people with hemophilia and will continue to be a key focus for Baxalta,'' said Dr. John Orloff, vice president and global head of research and development at Baxalta. ''We continue to advance this program as we learn more about this new concept and its value for those living with hemophilia, with an opportunity to truly transform the treatment paradigm.''

- here's the release