1406 GMT - Drugmakers Sanofi and Regeneron Pharmaceuticals seem to be exploring ways to work more strategically together again, Jefferies analysts say in a research note. They could work on extending the lifecycle of their blockbuster drug Dupixent or on next-generation immunology assets, even though neither company disclosed a new collaboration in recent earnings calls, the analysts say. The tone from executives at both Sanofi and Regeneron seemed to shift from their somewhat transactional relationship over the last few years, Jefferies says. Sanofi shares rise 2%, Regeneron's are little changed.