Despite entreaties from a handful of lawmakers and a burgeoning grassroots movement of prostate cancer patients and physicians, the House Energy and Commerce Committee won’t investigate the Food and Drug Administration’s decision not to approve a new treatment.

The FDA’s surprising actions set in motion speculation among cancer patients, pharmaceutical investors, lawmakers and others that the agency is engaged in a cover-up to protect two outside advisers who, Provenge advocates allege, have ties to Dendreon’s competitors.

At the urging of Provenge supporters, at least six lawmakers asked the committee to investigate whether the FDA was unduly influenced by those outside advisers.

The grassroots campaign spearheaded by prostate cancer patients that generated some interest on Capitol Hill, however, has failed to sway the leaders of the House committee that oversees the FDA.

In a letter to four lawmakers Wednesday, committee Chairman John Dingell (D-Mich.) and Health Subcommittee Chairman Frank Pallone Jr. (D-N.J.) maintain it would be inappropriate for the committee to begin an investigation while the FDA is still evaluating the drug.

Patients and investors have been eager for Congress to intervene in the FDA’s decision in December not to approve Provenge despite overwhelming favorable recommendations from two influential advisory committees. One committee voted 17-0 that the FDA should approve Provenge and another voted for the drug 13-4.

Last May, the FDA demanded additional information from Dendreon on the medication, saying it was unconvinced that the vaccine actually was effective at treating prostate cancer. Provenge advocates allege that two of the dissenting advisory committee members contacted FDA officials to urge them not to approve the medicine.

The patients advocating for approval of Provenge contend that the medicine should be permitted on to the market because of its potential to alleviate the severe and often fatal disease, despite the FDA’s misgivings.

At the urging of constituents, letters from rank-and-file House members began flowing to the Energy and Commerce Committee in December, starting with a missive from Reps. Mike Michaud (D-Maine), Dan Burton (R-Ind.) and Tim Ryan (D-Ohio). Later, Reps. Chris Van Hollen (D-Md.), Patrick Murphy (D-Pa.) and Vern Buchanan (R-Fla.) joined the effort.

The lawmakers want the panel to investigate whether the alleged conflicts of interest affected the FDA’s actions.

Although Dingell and Pallone describe these concerns as “serious,” they conclude that the FDA should be permitted to continue its review of the drug unabated by Congress.

“[I]t is the practice of this committee to allow a regulatory agency such as FDA to complete its statutorily mandated processes and render a final decision before initiating a formal investigative action. An investigative hearing prior to an agency’s final decision runs the risk of interfering with the normal regulatory process,” Dingell and Pallone wrote.

Moreover, the letter notes that the two advisers in question were cleared to sit on the committee according to standard FDA procedures. “An initial examination of the panel in question here indicates that each individual’s financial interests were disclosed and that appropriate waivers were granted in writing,” Dingell and Pallone wrote.

Michaud responded to Dingell's decision with a vow to keep pressing. "I am deeply disappointed with the Energy and Commerce Committee's decision," he said in a written statement to The Hill. " I don't think this is the end to the issue.  Congress needs to get to the bottom of this.  I am exploring other possibilities to bring attention to this serious matter."

Dingell’s decision not to pursue the Provenge advocates’ agenda is likely to spark renewed efforts on the part of patients and doctors to pressure the FDA and Congress about the drug.

A prostate-cancer advocacy group called A Right to Live for Cancer Patients reacted to the news by vowing to dial up their campaign.

“We at A Right to Live, on behalf of late-stage cancer patients across this country, remain hopeful that other informed members of Congress will pick up and support the call for further investigations and will not allow these men to have died in vain. Many members have already pledged their support for our efforts and for that, we are thankful. Many more will be needed to deliver meaningful and sustainable change to a system that is currently ‘hanging on by its fingertips’ trying to keep up with the myriad scientific advances taking place all around it,” the group’s director, Scott Riccio, said in a written statement.

After the FDA’s May decision, A Right to Live launched a grassroots campaign contesting it. In addition to rallies and protests, the group organized patients to contact their lawmakers. The controversy also gave birth to the groups CareToLive and Physicians for Provenge.

Also pending is a lawsuit filed by CareToLive against the FDA and Commissioner Andrew von Eschenbach. The patients’ group alleges that the FDA violated the Freedom of Information Act by refusing to turn over alleged correspondence between the two dissenting committee members and FDA officials including von Eschenbach.