Recombinant human interleukin-11 is unlikely to stimulate the growth of the most common solid tumors

Recombinant human interleukin-11 (rhlL-11)has been shown to enhance recover y from thrombocytopenia and mucosal injury after cancer chemotherapy. Since RNA for the receptor and signal transducer for IL-ll is detected in many c ell types including some cancer cells, it was theoretically possible that r hlL-11 could affect the growth of tumor cells. This study was intended to d etermine whether rhlL-11 stimulates the proliferation of human tumor colony -forming units (TCFUs) taken directly from patients, Tumor cells were cultu red in soft agar and continuously exposed to three concentrations of rhlL-1 1 (1.0, 10.0 and 100.0 U/ml) for 14 days in the capillary cloning system. G rowth stimulation was noted in two of 66 (3%) of evaluable specimens, inclu ding one of 14 evaluable non-small cell lung cancer and one of five evaluab le colon cancer specimens. In these two specimens, there was no increased s timulation of TCFUs with escalating concentrations of rhlL-11. Interestingl y, the highest concentration of rhlL-11 tested inhibited the growth of 16 s pecimens (24.2%; 95% confidence interval 13.9-34.5%). Growth inhibition dem onstrated a concentration-response relationship (p<0.001), These results su ggest that rhlL-11 appears unlikely to stimulate the growth of the most com mon solid tumors. [(C) 1999 Lippincott Williams & Wilkins.]