Eli Lilly and Pfizer have another positive phase 3 trial for their nerve growth factor-targeting drug tanezumab, showing effective pain relief in chronic lower back pain (CLBP).
The efficacy data back up the findings of two earlier phase 3 trials in osteoarthritis last year, but once again safety concerns that have undermined the NGF inhibitor class for years havent been dispelled by the results.
In the CLBP study, the higher 10mg dose of tanezumab was able to show a statistically significant improvement in pain at 16 weeks compared to placebo, although the lower 5mg dose failed to meet this objective. Full details will be presented at a medical conference later this year.
Turning to the safety data, Lilly and Pfizer reveal that 1.4% of all tanezumab-treated patients suffered rapidly progressive osteoarthritis, compared to 0.1% of the placebo group. There were no cases of osteonecrosis leading to rapid joint destruction (arthropathy), a side effect that prompted the FDA to slap a clinical hold on the entire NGF inhibitor class in 2010.
Nevertheless, rapidly-progressing osteoarthritis seems to be a risk associated with all the NGF inhibitors tested to date, and could be problematic given that these drugs are intended for conditions that effect millions of people.
The class has a lengthy list of discontinued candidates, mainly due to safety issues, including Johnson & John/Amgens fulranumab and candidates from AstraZeneca and AbbVie. Pfizer/Lillys tanezumab along with Regeneron/Tevas fasinumab which reported positive phase 3 results in osteoarthritis last year are the only NGF-targeting drugs that remain in late-stage development.
Regeneron revealed last year it had halted a high-dose arm in its study after a risk-benefit assessment suggested some patients might be at risk of what George Yancopoulos, Regenerons chief scientific officer, had described as rapidly-progressing osteoarthritis.
Pfizer and Lilly have been fairly guarded about the prospects for tanezumab so far, but seem to be getting more optimistic about a path to approval.
We look forward to further analysing these results, and believe the data from this study will support our planned future global regulatory submissions inback pain, said Ken Verburg, tanezumab development team leader at Pfizer.
Pfizer and Lillys development programme for the drug includes several pivotal studies in osteoarthritis, CLBP and cancer pain due to bone metastases, with two further trials in osteoarthritis and CLBP due to report before the end of the year.
The market for drugs that deliver effective pain relief without the risk of side effects and addiction linked to opioid analgesics could be massive, and that is driving the development of the NGF inhibitors despite the risks.
In contrast to opioids, which alter pain perception by targeting opioid receptors, NGF inhibitors block signalling of a pathway activated in response to injury, inflammation, or chronic pain.
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