By Manas Mishra

(Reuters) -France's Sanofi reported first-quarter profit that beat analysts' expectations on Thursday, boosted by strong demand for its anti-inflammatory drug Dupixent, as well as newer treatments and vaccines.

However, the company left its full-year profit and sales forecasts unchanged, with Chief Financial Officer François-Xavier Roger flagging a "a volatile world where a number of things are difficult to predict."

Sanofi results come as healthcare investors brace for potential tariffs by U.S. President Donald Trump on the sector after his administration announced probes into imports of pharmaceuticals.

CFO Roger said at a press briefing that the company, which has been increasing its manufacturing presence in the United States, would consider more investments in the US, based on future needs.

Drugmakers have argued that tariffs could increase the chance of shortages and reduce access for patients.

In the quarter, business operating income, excluding one-off items, rose 20.1% to 2.90 billion euros ($3.29 billion), surpassing the average analyst estimate of 2.68 billion euros.

Sanofi has ramped up research and development spending in recent years, prompting the company to abandon its long-term margin targets two years ago, as it seeks to build on the success of its blockbuster drug Dupixent and develop the next wave of growth drivers.

"We stand by our strategic choice to invest significantly in our future with our R&D focus," Roger said.

Sales of its blockbuster asthma drug Dupixent rose 20.3% to 3.48 billion euros, compared with 3.44 billion euros expected on average by analysts.

Sales of Beyfortus, a new treatment to protect newborns from a common respiratory virus, jumped 54.9% to 284 million euros, compared with analysts' estimate of 215 million euros.

($1 = 0.8820 euros)

(Reporting by Manas Mishra in Bengaluru; Editing by Nivedita Bhattacharjee and Sherry Jacob-Phillips)