“Ignoring the cost of care is no longer tenable,” they wrote. ”Soaring spending has presented the medical community with a new obligation. When choosing treatments for patients, we have to consider the financial strains they may cause alongside the benefits they may deliver.”

Sanofi executives argued that the price they had set was very similar to that of Avastin. “The intent was not to charge a premium,” Christopher A. Viehbacher, the chief executive of Sanofi, said in an interview last month.

Sloan-Kettering, he said, was basing its price comparison on a dose of Avastin that was half the dose Sanofi used in its own comparison.

On Thursday, Sanofi backed down. “We believe that Zaltrap is priced competitively as used in real-world situations,” it said in a statement. “However, we recognize that there was some market resistance to the perceived relative price of Zaltrap in the U.S. — especially in light of low awareness of Zaltrap in the U.S. market. As such, we are taking immediate action across the U.S. oncology community to reduce the net cost of Zaltrap.”

The move was first reported on Thursday by The Cancer Letter, a newsletter about cancer issues.

Sanofi said it would not change the official price for Zaltrap but would offer discounts of about 50 percent. Zaltrap, which is given intravenously, is not bought directly by patients but is sold to doctors or hospitals, which administer it. The cost is then reimbursed by Medicare or private insurers. Patients could be liable for a co-payment.