October 02, 2008 Merck pipeline now looking slimmer with the demise of taranabant Lisa Urquhart Merck & Co’s decision to call a halt to phase III trials of obesity treatment, taranabant, due to psychological issues is likely to call into question the future of the whole cannabinoid type 1 antagonist class following Sanofi-Avenits’ resounding failure last year to get US approval for similar product Acomplia, also due to psychiatric side effects. In studies taranabant showed increases in anxiety, irritability and depression; symptoms that were worryingly exacerbated according to higher doses of the drug. Alongside potentially sounding the death knell for the class of drugs that were designed to work on the same part of the brain that responds to marijuana, Merck’s action also highlights the increasing difficulty big pharma companies are experiencing in bringing obesity drugs to the market. Earlier this week, Pfizer announced that it would be exiting the indication to concentrate on slightly less troublesome therapy areas such as oncology. Lowering expectations As to how much of a blow this will be to Merck & Co is debatable. While the drug was the second most valuable in its pipeline and worth $777m to the company, according to EvaluatePharma's NPV Analyzer, the problems with Acomplia had seen analysts lower their forecasts for a number of cannabinoid type 1 antagonists currently in development. Over the last 12 months, 2012 sales forecasts for taranabant, which briefly rose in July, have drifted down by $41m to $229m, and they are a long cry from the $459m they were forecast to reach in February 2007. But the most dramatic fall in market expectations for a drug in this class has been for that of Acomplia, which back in February 2007 was forecast to have 2012 sales of a whopping $4bn. Following the suicides of three people taking the drug, and failure to get US approval, this has fallen dramatically to the current consensus of $543m. So those remaining in the field, which will now not include Pfizer’s otenabant if it sticks to its word, are more than likely to see already low sales forecasts for their drugs drift down even further following this latest setback. Cannabinoid type 1 antagonist: Top 10 Products in 2014 Annual Sales WW - Sales Generic Phase CAGR (07 - Rank Product Company 2007 2014 Name (Current) 14) 1 Acomplia/Zimulti rimonabant Sanofi-Aventis Marketed 108 713 31% 2 MK-0364 taranabant Merck & Co Phase III - 409 n/a 3 CP-945,598 otenabant Pfizer Phase III - 166 n/a Bristol-Myers 4 SLV 319 ibipinabant Phase II - 50 n/a Squibb - AVE-1625 - Sanofi-Aventis Phase III - - - - SLV 319 ibipinabant Solvay Phase II - - - - AZD2207 - AstraZeneca Phase II - - - Surinabant (SR - surinabant Sanofi-Aventis Phase II - - - 147778) - V24343 - Vernalis Phase I - - - Schering- - Org 50189 - Phase I - - - Plough Total 108 1,337 43% More from Evaluate Vantage Evaluate HQ 44-(0)20-7377-0800 Evaluate Americas +1-617-573-9450 Evaluate APAC +81-(0)80-1164-4754 © Copyright 2021 Evaluate Ltd..