February 9, 2010 (San Antonio, Texas) — Researchers are reporting further encouraging results with the anti–nerve growth factor tanezumab in phase 2 studies examining its effects in the treatment of osteoarthritis of the knee and interstitial cystitis, according to results presented here at the American Academy of Pain Medicine 26th Annual Meeting.
Together with previously presented results that showed it was effective in treating chronic lower back pain, tanezumab may be gaining traction, although treatment was also associated with a higher number of adverse events, particularly abnormal peripheral sensation.
“In 3 different types of chronic pain, tanezumab was effective in phase 2 studies,” presenting study author and Pfizer senior medical director Leslie Tive, PhD, told Medscape Neurology. All studies were funded by Pfizer.
Phase 2 Studies
The still-investigational drug is a monoclonal antibody with an affinity for nerve growth factor, a neurotrophin with a role in pain signaling and pain pathophysiology.
Tanezumab produced statistically significant improvements over placebo in all 5 doses that were used in patients with walking knee pain.
With about 70 patients in each group, pain measured according to the visual analog scale was reduced beginning at the first week and lasting through week 16, the last week for which results were available. The P value for the week 16 change was <.001.
The optimal dose, researchers found, was 10 mg.
As for interstitial cystitis, involving chronic inflammation of the bladder wall, tanezumab produced a difference of more than 1 point better than placebo on the numerical rating scale in a 64-patient trial, which was considered clinically significant.
That difference appeared at week 6, but the effect trailed off after that. The average pain score for tanezumab during the entire 16-week period was 6.4 vs 5.9 in the placebo group.
The week 6 confidence interval did not cross zero, but the week 16 figure did.
In the chronic lower back pain trial, tanezumab produced pain scores significantly better than both placebo (P < .001) and the active comparator naproxen (P < .01) after 12 weeks. This indication is now in phase 3 studies.
Although adverse events overall were as expected from previous trials, there was a much higher rate of abnormal peripheral sensation with tanezumab, with the most common being paresthesia, hyperesthesia, and hypoesthesia.
Just over 14% of tanezumab patients reported such events, compared with just over 3% of the naproxen patients, but researchers said most were rated as “mild” and were not associated with substantial or clinically meaningful neurologic deficits.
“We do think that this is a function of the drug,” Dr. Tive said. However, “Very few of these patients drop out. It seems to be a transient effect.” Most patients experience these problems after the first dose, but it usually stopped after that, she said.
Good Efficacy, High Side Effects
Timothy Deer, MD, the meeting’s committee cochair, said some ill effects could be expected with the new drug, but it remains to be seen how serious they are.
“Many first-generation drugs of any type have good efficacy but they have a high side effect profile, adverse effect outcome, then the next generation looks at that,” he told Medscape Neurology.
He said tanezumab is part of a trend toward more use of growth factor–related drugs and genetic therapies in treatment of pain. “I think it could be an important part of our future treatment,” Dr. Deer said.
The study was funded by Pfizer, the maker of tanezumab. Dr. Tive is senior medical director with Pfizer. Dr. Deer has disclosed no relevant financial relationships.
American Academy of Pain Medicine (AAPM) 26th Annual Meeting: Poster 151. Presented February 3-5, 2010.
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Cite this: More Favorable Results With Tanezumab for Various Pain Types - Medscape - Feb 09, 2010.