A broad coalition of patent holders and inventors, including drugmakers and universities, is urging members of Congress to take a cautious approach as it considers legislation designed to curb frivolous lawsuits by so-called patent trolls. Republicans in the House of Representatives are expected to revive previous proposals to push back on companies accused of extracting settlements from start-ups with threats of litigation. In a letter to lawmakers, the 250-member coalition warns that some proposals under consideration would “weaken the overall patent system and diminish innovation and job creation in the U.S.” Several major developments in patent law over the past year call into question the need for sweeping new legislation, the coalition says. The organizations note that the Supreme Court issued rulings in five cases that should help discourage the filing of questionable patent infringement claims. Coalition members include trade associations such as the Pharmaceutical Research & Manufacturers of America, the Biotechnology Industry Organization, and the Association of American Universities.