12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced increase in depressed white blood cell counts in patients treated with cytotoxic cancer chemotherapeutic drugs

Fifty-two patients with solid tumors had depressed white blood cell and neutrophil counts because of prior treatment with cytotoxic cancer chemotherapeutic drugs. These patients were given one or more i.v. infusions of 0.125–0.25 mg of 12-O-tetradecanoylphorbol-13-acetate (TPA), and this treatment increased the low white blood cell and neutrophil counts toward the normal range. The average white blood cell and neutrophil counts were 2.55 × 109 /liter and 1.76 × 109 /liter, respectively, before treatment with TPA. After one or more i.v. infusions of TPA, the white blood cell and neutrophil counts increased to peak values of 5.92 × 109 /liter and 4.76 × 109 /liter, respectively, within a few days. Most patients had increased levels of white blood cells and neutrophils by 24 hr after a single i.v. infusion of 0.25 mg TPA. Elevated levels were observed for at least 3 days. This study demonstrates that treatment with parenteral TPA is feasible with useful biological activity. Only mild and reversible side effects were observed.