Unity Biotechnology has raised an enormous amount of funding from investors and the public markets in order to advance a pipeline of small molecule senolytic drugs. They are presently somewhat ahead of the numerous other senolytic startup biotechnology companies in terms of the road to the clinic. Senolytic compounds are those that can selectively destroy senescent cells in old tissues, thereby removing the contribution of these cells to the aging process. This is literally rejuvenation, albeit quite narrowly focused on just one of the many causes of aging.

It is disappointing that Unity Biotechnology principals are either choosing a strategy of local administration of their drugs, or are forced into it because they consider the drugs too toxic for systemic administration. Senescent cells cause chronic inflammation via secreted signal molecules, the senescence-associated secretory phenotype (SASP). While researchers have demonstrated benefits to local clearance of senescent cells in in joints, gaining regulatory approval for only local administration blocks the vast opportunity for off-label use as a general rejuvenation therapy. That only emerges for compounds that can be systemically administered to destroy senescent cells throughout the body.

To hear Nathanial David tell it, the osteoarthritis drug his Unity Biotechnology began testing in human subjects last fall is about far more than just helping aging weekend warriors regrow cartilage in their damaged knees. It's the first step toward making us all feel young again. David, was explaining the science behind UBX0101, the drug Unity has in late phase 1 clinical trials to treat the intractable arthritic condition, which affects 14 million Americans. The company is expected to release early results within the next several weeks.

The potential payoff from the company's arthritis drug ensures investors are watching carefully. After collecting 222 million in venture capital from Jeff Bezos, Peter Thiel, Fidelity, and others on the strength of its preclinical studies, Unity went public last May, raising 85 million in an initial public offering that valued the biotech at 700 million. In 2017 researchers funded by Unity demonstrating that removing senescent cells from the injured knees of mice using UBX0101 not only reduced pain, but also prompted the joint to regrow cartilage. The scientists later repeated the finding using human knee tissue removed from patients who'd undergone total joint replacements.

Last fall doctors began injecting UBX0101 into the knees of older human patients suffering from moderate to severe osteoarthritis. Unity's selection of osteoarthritis of the knee as its first target allows the team to administer the drug locally in the joint and closely monitor how it affects the aged cells around it. Unity announced earlier this year that it's also seeking FDA approval to begin human testing for a second locally administered drug, UBX1967, that would target age-related eye diseases.