Under a separate deal with Regeneron, Mitsubishi Tanabe Pharma has exclusive development and commercial rights to fasinumab in Japan, Korea and nine other Asian countries.
The FDA has also requested an amendment to the study protocol following its observation of a case adjudicating arthropathy in a patient, who received high dosage of fasinumab.
Regeneron has stopped dosing in the study after completing an unplanned interim review of the data which demonstrated evidence of efficacy over placebo at the eight- and 12-week time points. Patients will continue to be followed for up to 36 weeks.
Based on these data, the companies intend to design a pivotal Phase 3 study in chronic low back pain that excludes patients with advanced osteoarthritis.
Regeneron chief scientific officer and Regeneron Laboratories president George Yancopoulos said: "We are making data-driven decisions on Phase 3 fasinumab dosing that we believe will maximize potential benefit for patients in need, while minimizing the likelihood of side effects.
"We look forward to working with global health authorities to advance this important investigational therapy for patients with often difficult-to-treat osteoarthritis pain and chronic low back pain."
Fasinumab is a fully human monoclonal antibody that targets NGF, a protein that plays a key role in the regulation of pain signaling.
Regeneron said evidence suggests that NGF levels are elevated in patients with chronic pain conditions.
Image: FDA Building 51 houses the Center for Drug Evaluation and Research. Photo: courtesy of The U.S. Food and Drug Administration.