Riggins’ Mice and Fenbendazole – The Rest of the Cancer Story

Fenbendazole Mice Study

By now, everyone should know the serendipitous story of Dr. Gregory Riggins and his legendary mice, those rodents whose cancers disappeared following a pinworm treatment. The drug that treated their worms also stopped their brain tumors.

This antiparasitic drug, Fenbendazole (FBZ), and its human counterpart, Mebendazole (MBZ), have been tested and used successfully against various aggressive cancers. In particular, the METRIC trial used MBZ as part of its patented 4-Drug COC cocktail that essentially doubled the survival of GBM patients.

But what many readers need to learn are the details of how this all began and what the first study showed following this chance discovery. Sometimes legends evolve, and it helps to examine the precise details to uncover factual inconsistencies that may lead to improved scientific insights.

Three researchers from Johns Hopkins published the first “Riggins Mice” study in a Veterinary Journal on November 1, 2008. However, Johns Hopkins’ “Doorway to Discovery” article dates the Riggins’ mice back to a Hopkins Laboratory in 2009. Drs. Gao, Dang, and Watson submitted their article for publication on May 8, 2008, a full year earlier. Their study was accepted for publication on July 16, 2008, and published in the Journal of the American Association for Laboratory Science. This fact suggests the date in “Doorway to Discovery” was off by at least one year.

The Gao et al. study was entitled “Unexpected Antitumorigenic Effect of Fenbendazole when Combined with Supplementary Vitamins.”  And this is where it gets interesting. The study found that FBZ did not shrink the tumors by itself. Only when FBZ was combined with Vitamins did the cancers shrink. Even more interesting was that without the Vitamins, the FBZ seemed to stimulate tumor growth.

The researchers compared four groups of mice in a study designed to mimic what Riggins initially observed in his pinworm mice. But because the Riggins’ mice also received supplemental vitamins in their chow, Gao and colleagues had three study groups, a Vitamins + FBZ group, an FBZ without Vitamins group, and a Vitamins-only group. These three groups were compared to a control group without Vitamins or FBZ.

Tumors in the FBZ-only group were measured at almost twice the size of the control group, while the smallest tumors at a fraction of the control groups’ size were found in the FBZ + Vitamins group. The Vitamins only group was nearly indistinguishable in size from the controls. Something in the Vitamins + FBZ seemed to augment the antitumor effect of FBZ alone, but what?