* Analysts slash Lantus sales forecasts on cancer concerns
* Novo, Merck, Amylin/Lilly, Astra/Bristol could all benefit
* Novo gains 5 percent, Sanofi up 1 percent after last week's losses
By Ben Hirschler, European Pharmaceuticals Correspondent
LONDON, June 29 (Reuters) - Rival drugmakers look set to gain from a possible link between cancer and Sanofi-Aventis's long-acting insulin drug Lantus, which has prompted analysts to slash sales forecasts for the product.
Winners could include Denmark's Novo Nordisk -- provided its rival long-acting insulin Levemir remains free of similar safety issues -- as well as makers of two new types of diabetes medicines, known as GLP-1s and DPP-4s.
Shares in Novo Nordisk, the world leader in diabetes care, jumped 5 percent on Monday as the group moved to distance itself from Lantus by highlighting the technical differences of its artificial, or analogue, versions of insulin.
Novo stock had fallen 6 percent last week.
Industry analysts said other potential beneficiaries included Amylin Pharmaceuticals and Eli Lilly, which market the GLP-1 drug Byetta; Merck & Co, which sells the DPP-4 treatment Januvia; and AstraZeneca and Bristol-Myers Squibb, which expect to get approval soon for a new DPP-4 treatment called Onglyza.
"We imagine that Novo Nordisk, Merck, Amylin/Lilly will actively step up their marketing efforts in the wake of the Lantus safety concerns," Morgan Stanley analyst Andrew Baum said in a research note.
JP Morgan analysts said Novo could win on two fronts, if Levemir succeeds in winning market from Lantus and the company's GLP-1 drug Victoza, which is about to go on sale in Europe, does well.
Novo's Chief Executive Lars Sorensen, however, was cautious. "It is too early to say what this will mean to the dynamics of the market," he told investors in a conference call on Monday morning.
KEY SALES PROP
Sanofi moved quickly to stress that the findings from four European registry studies identifying a possible link to cancer were inconclusive. The data was released after the market close on Friday.
Still, the experience of past scares, involving drugs such as GlaxoSmithKline's Avandia and Merck and Schering-Plough's Vytorin, suggests many doctors and patients will play safe by seeking alternative treatments.
That threatens to knock away a key prop to Sanofi's sales and profit growth.
Lantus, which sold 2.45 billion euros ($3.43 billion) in 2008, has been seen as Sanofi's main driver as top drugs like Plavix and Lovenox face the threat of generic competition.
Morgan Stanley cut its Lantus sales and earnings per share (EPS) estimates by 52 percent and 11 percent in 2010 and 85 percent and 23 percent in 2015, respectively.
Societe Generale analysts said they now forecast zero growth for Lantus for most of the second half of this year and just mid-single digit growth from 2010 onward, implying 2012 Lantus sales of 3.4 billion euros, compared with Sanofi's previous guidance of at least 5 billion.
That translates into a cut of around 10 percent in 2010/2011 EPS estimates, they added.
SocGen cuts its price target for Sanofi to 47 euros a share, but held its "buy" rating.
Many other brokers moved swiftly to downgrade the stock on Monday, including JP Morgan, Exane and Natixis.
Shares in Sanofi, which had already fallen more than 12 percent on Thursday and Friday on mounting speculation that damaging data was about to be published, edged up 1 percent to 41.30 euros by 0850 GMT.
(Additional reporting by Karin Jensen in Copenhagen; Editing by Erica Billingham)