Monoclonal antibodies light up rat tissue culture

I wrote about the cancer drug ipilimumab last year, which has been hailed as miraculous by some. The drug has been through Phase 3 clinical trials and results will be presented on June 6 at the annual meeting of the American Society of Clinical Oncology (ASCO).

Meanwhile, following announcements of the miracle cure in three men having prostate cancer, ipilimumab has also been show to be modestly effect against lung cancer, according to the company.

Ipilimumab works by targeting an inhibitor of the immune system called CTLA-4 (cytotoxic T lymphocyte-associated antigen 4) and subsequently boosting the response of the killer T-cells. It belongs to the highly promising monoclonal antibody field of therapeutics.

Quote from a press release sounds like the company is excited:

“We are excited by the potential of immuno-oncology, an entirely new paradigm in the treatment of multiple types of cancer in which a patient’s own immune system is activated to fight cancer cells,” said Elliott Sigal, M.D., Ph.D., executive vice president, chief scientific officer and president, Research and Development, Bristol-Myers Squibb.

“We are leading the way with ipilimumab, the most advanced investigational compound in our immuno-oncology portfolio, in testing this new paradigm and we look forward to presenting results from the ipilimumab clinical development program at this year’s American Society of Clinical Oncology Annual Meeting.”

But while the promise of the basic science is cool, it’ll be difficult to draw conclusions about the real-world application of the drug until the results are formally presented and peer reviewed.

Mayo has not included a summary of Phase 2 clinical trials of the drug in its news, as pointed out in Seeking Alpha. The Phase 2 results were presented at the Memorial Sloan-Kettering Cancer Center on May 29-June 2, 2009.

In their report, researchers said that of the 45 patients had been treated with the drug (16 with Ipilimumab alone, 15 with the Ipilimumab + other drugs, and 14 with Ipilimumab + other drugs + chemotherapy).

Antibody declines of 50% or greater were seen in 10 out of the 45 patients, or 22%.  Only one patient who was solely treated with Ipilimumab demonstrated complete resolution of lesions.

Alas, the drug may not be so successful as the hype suggests.  Why did the researchers release the results of just two patients, with no reference to the larger study presented at the conference? Something shady.  Others agree.