Bamboo is the largest and one of the fastest growing members of the grass family, with individual shoots reaching their full height in a single growing season. In an apt metaphor, Pfizer Inc. made quick work of privately held Bamboo Therapeutics Inc., paying $150 million up front and committing to milestone payments of up to $495 million just months after investing $43 million for a 22 percent equity stake in the Chapel Hill, N.C.-based company.

Bamboo, which has preclinical neuromuscular and central nervous system programs from its recombinant adeno-associated virus (rAAV) vector technology and a fully operational phase I/II gene therapy manufacturing facility, will operate as a wholly owned subsidiary of New York-based Pfizer.

The acquisition provides Pfizer with access to Bamboo's vector design technologies, including chimeric rAAV, self-complementary and dual glycan receptor rAAV. The technologies are designed to improve the efficiency of delivering therapeutic genes into host cells.

"We believe that Bamboo has innovative, leading expertise, technologies and manufacturing capabilities and assets in the field of gene therapy that complement Pfizer's existing capabilities," Pfizer spokesman Dean Mastrojohn told BioWorld Today. "Bamboo will help accelerate our strategy for becoming a leader in gene therapy."

Mastrojohn was silent on timing of the deal, including the prospect of a competitive bid, and Bamboo officials did not respond to BioWorld. But Bamboo's rAAV-based gene therapies complement Pfizer's rare disease and gene therapy portfolios in two priority areas, according to Mastrojohn.

In neuromuscular disease, Bamboo has a preclinical asset for Duchenne muscular dystrophy (DMD), BMB-D001, that is positioned to enter the clinic next year. Pfizer, meanwhile, is advancing PF-06252616 (domagrozumab), an anti-growth depleting factor-8, or GDF-8 monoclonal antibody that has reached 50 percent enrollment in a phase II trial. The antibody has the potential to inhibit myostatin signaling, which inhibits muscle differentiation and growth in patients with muscle-wasting diseases such as DMD. Pfizer's randomized, double-blind, placebo-controlled, multiple-ascending dose study is expected to recruit approximately 105 ambulatory boys with DMD, with a primary efficacy endpoint of mean change from baseline on the 4 stair climb, compared to placebo, according to Thomson Reuters Cortellis.

Bamboo's central nervous system portfolio includes preclinical assets for Friedreich's ataxia and the rare disorder Canavan disease as well as a phase I asset for giant axonal neuropathy.

Another appealing asset: Bamboo's gene therapy manufacturing facility, acquired earlier this year from the University of North Carolina (UNC) at Chapel Hill. Terms of that deal were not disclosed, but the 11,000-sq. ft. facility, known as the UNC Vector Core, was founded in 1993 as a full-service viral vector production organization and has produced multiple research- and clinical-grade lots for biopharma companies and academic institutions.

Bamboo's suspension, cell-based production platform uses serum-free media to increase scalability, efficiency and purity. Its manufacturing system is said to decrease the number of processing steps in methods that use adherent cells while reducing the variability and shortcomings associated with the use of animal serum, resulting in superior vector yields at lower costs.

'GENE THERAPY STANDS A GOOD CHANCE'

Bamboo's technology and pipeline were sufficiently compelling to attract funding in January from CureDuchenne Ventures LLC, the investment arm of the nonprofit CureDuchenne. The amount was not disclosed, but in February Bamboo quietly posted an SEC filing disclosing an equity raise of $49.5 million.

Debra Miller, co-founder, president and CEO of CureDuchenne, said the patient advocacy organization conducted extensive due diligence on Bamboo before its January stake and found two major factors to its liking. The first was the work of Richard Jude Samulski, the company's scientific founder, chief scientific officer and executive chairman. The career of the AAV researcher stretches back more than two decades, including the most recent eight years as director of the University of North Carolina Gene Therapy Center.

"We were able to see animal data that looked really, really positive," Miller told BioWorld Today. "They believe they have a good chance at success in gene therapy as it relates to the delivery of dystrophin."

The other attractive factor, Miller said, was Bamboo's manufacturing facility. The CureDuchenne investment was designed to help accelerate Bamboo's transition into a fully integrated gene therapy company.

"Combining the expertise of the scientific team along with the ability actually to produce the vector offered a very attractive package deal for a company like Pfizer," Miller said.

Samulski demonstrated the first use of AAV as a viral vector, culminating in the first U.S. patent involving non-AAV genes inserted into AAV. A serial entrepreneur, he also had a hand in founding Merlin Pharmaceutical Corp. as well as Asklepios Biopharmaceutical Inc. (AskBio) and its affiliate, Chatham Therapeutics LLC – picked up in 2014 by Baxter International Inc. (now Baxalta Inc.) for $70 million. (See BioWorld Today, April 3, 2014.)

Samulski's previous start-ups also were focused on AAV-based gene therapy. Merlin was acquired in 1995 by Somatix Therapy Corp., which also teamed up with Baxter in multiple hemophilia gene therapy deals. Somatix subsequently merged in 1997 with Cell Genesys Inc. in a $115 million stock swap. (See BioWorld Today, Nov. 4, 1993, Nov. 10, 1994, Dec. 21, 1994, Feb. 15, 1995, and Jan. 14, 1997.)

Chatham's gene therapy platform included a hemophilia B program that was part of a 2012 collaboration with Baxter to evaluate BAX 335, as well as a preclinical hemophilia A program and potential applications to future hemophilia treatments. AskBio is developing a biological nanoparticle, or BNP, gene delivery technology for therapies targeting heart, central nervous system, muscle, ocular and liver diseases.

Miller was optimistic about prospects for accelerating the Bamboo assets under Pfizer's tutelage.

"Pfizer brings phenomenal resources," she said, "especially since they're already committed to rare diseases, including Duchenne, where they're working diligently on their anti-myostatin product. I think it's a real plus that they're taking on this project. Since Duchenne is a primary focus of Bamboo, that asset represents much of the value of the company."

To date, no gene therapy products have been approved in the U.S., but Pfizer has sown some seeds in a number of areas. In 2014, the company established its Genetic Medicines Institute, a dedicated gene therapy research group, within its Rare Disease Research Unit. The same year, Pfizer established a collaboration with Philadelphia-based Spark Therapeutics Inc. on the clinical program for SPK-9001, in development as a one-time treatment for hemophilia B. In May, the companies reported encouraging initial data from an ongoing phase I/II trial for the treatment, which has breakthrough therapy designation from the FDA. (See BioWorld Today, Dec. 9, 2014, and May 20, 2016.)

Pfizer also has research agreements with King's College London to develop a series of rAAV gene therapy vectors and with the University of Iowa Research Foundation to advance a potential gene therapy for cystic fibrosis. And the pharma has a collaboration and license agreement – along with an equity stake – with 4D Molecular Therapeutics, of Emeryville, Calif., to discover and develop next-generation rAAV vectors for cardiac disease.

CureDuchenne, which had a bird's-eye view of the numerous disappointments in the DMD space over the past year, remains hopeful about the potential for therapies to treat "the whole disease – not just dystrophin replacement, but cardiac, inflammation and some of the other issues," Miller said. "Over the last few years, we've been looking for the next generation of treatments, and we do believe that gene therapy stands a good chance."