WASHINGTON — Congressional progressives secured a series of changes to the sweeping drug pricing bill the House is considering this week in return for dropping a threat to upend the vote altogether.

The changes do not significantly change Speaker Nancy Pelosi’s reforms, which would let Medicare negotiate the prices of certain high-cost drugs. Their tweaks include a slight increase in the number of drugs that would be negotiated each year, from 35 to 50, and a provision that will pave the path, but not explicitly enact, another policy meant to block drug makers from hiking their prices more than inflation.