The stock fell by more than a third after on the speculation about Exubera - intended as a replacement for insulin injections and developed by Nektar alongside Pfizer and Aventis - despite the fact that the only source for the story was a report on the French Agence de Presse Medicale and was subsequently picked up by analysts at Merrill Lynch.
Pfizer and Aventis only filed the dossier in Europe in March, and said that at present the application seems to be proceeding according to due process. Exubera has been tipped to achieve sales of €1.6 billion if approved for marketing.
Rumours of the European situation put a damper on Nektar's earlier announcement of a new agreement with Pfizer and Enzon for its PEGylation technology. Under the terms of the deal, Pfizer will use the PEGylation technology to improve the delivery of one of its drugs in development.
Exubera has had a troubled route through registration because despite its obvious appeal as an alternative to injections, some data have suggested that it may be associated with a decline in lung function over time. And as diabetes requires chronic dosing with insulin, the concern is that patients taking the drug in this way could have complications later on.
This has presented Nektar and its partners with a difficulty, as it is hard to prove in trials that exposure to Exubera for say 10 years would not cause problems. So regulators have to rely on short-term data and extrapolate the likely effects over the long term.
The Merrill Lynch analysts consider that the European Medicines Evaluation Agency will not give the go-ahead on the basis of the current dataset, and analysts at Prudential Securities have echoed this concern for the US market, where an application to market Exubera was withdrawn.
GSK exits INEX agreement
Meanwhile, there was bad news for another drug delivery specialist after UK drug major GlaxoSmithKline terminated its agreement with Canada's INEX Pharmaceuticals for the development of a lipsomal formulation of the anticancer agent topotecan (INX-0076).
The firms originally entered the collaboration in November 2001 and, although preclinical evaluation is complete, GSK says it has experienced a number of technical complications regarding the production of essential materials for planned clinical trials, significantly delaying the start of clinical development.
David Main, INEX' chief executive, said that the company is now considering the possibility of continuing development of the product alone.