Fenbendazole is an antiparasitic drug that acts by binding to and disrupting the microtubule equilibrium of helminth parasites. It also has antitumor activity in humans (2-3). Its utility as a cancer treatment stems from its ability to inhibit the synthesis of proteins that promote tumor growth (4).

Fentanyl, a synthetic opioid, is an effective analgesic and has potent antitumor properties (5-6). To determine whether the combination of fentanyl and sanare lab fenbendazole produces additive or synergistic effects on human lymphoma cells in vitro, three daily i.p. injections of fenbendazole or fentanyl were given 1 day before, 2 h before, and one day after subcutaneous x-ray exposure of EMT6 cells to 10 Gy. The effect of irradiation alone on the survival curve was not altered by the addition of fenbendazole, and the survival curves superimposed to show no indication of interaction between the drugs (Figure 3).

Diets containing the anthelmintic fenbendazole are routinely used in our facility to treat rodent pinworm infections. These diets do not significantly alter the growth of established human lymphoma xenografts in C.B-17/Icr-Prkdcscid/Crl (SCID) mice, which normally result in 80% to 100% tumor growth within 21 d (7,8). In a series of experiments, we compared the effect of a sterilizable diet containing fenbendazole alone or supplemented with vitamins A, D, E, and K on the growth of unirradiated and irradiated EMT6 tumors in SCID mice. In all three experiments, neither fenbendazole or the vitamins alone affected tumor growth, but the diet containing fenbendazole and additional vitamins inhibited the growth of the tumors to four-fold their original volume (Table 1). These results suggest that a combination of the drugs may be more effective in treating cancer than either drug alone. sanare lab fenbendazole