Senate Special Committee on Aging Chairman Herb Kohl (D-Wis.) is continuing his investigation into Genentech’s decision to limit the availability of cancer drug Avastin, questioning company officials on their decision and asking the FDA’s opinion on the move.

Avastin (bevacizumab) is approved to treat colorectal cancer and lung cancer but commonly is used off-label to treat advanced age-related macular degeneration (AMD). Genentech’s Lucentis (ranibizumab) was approved last year to treat AMD. The drugs are closely related and share the same mechanism of action.

However, the price difference between the drugs is significant. Avastin has a wholesale acquisition cost of $550 for 100 mg while Lucentis’ is $1,950 for 0.5 mg. Because the Centers for Medicare & Medicaid Services is a big purchaser of Avastin, limiting the drug’s availability could cost taxpayers $1 billion to $3 billion a year, Kohl said.

In a letter to Genentech Product Development President Susan Desmond-Hellman, Kohl requested documents related to discussions Genentech had with sponsors of a forthcoming study comparing Lucentis and Avastin. While Desmond-Hellman said she was unaware any negotiations took place, other sources told committee staff such talks did occur. 

Kohl asked Desmond-Hellman to provide documentation regarding Genentech’s decision to send a letter to an unknown number of patients warning them against using Avastin off-label and explaining its possible side effects. He also requested notes from a July board meeting and internal company notes regarding limiting Avastin or the relative costs of Lucentis and Avastin, including correspondence with the FDA about Avastin inspections.

Finally, Kohl asked FDA Commissioner Andrew von Eschenbach for the agency’s official position on Avastin’s availability. While Genentech employees say the FDA is opposed to the company providing Avastin to compounding pharmacies, committee staff has learned the agency has not indicated that Genentech should limit its supply of Avastin to those pharmacies, Kohl said.