Clin Cancer Res
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Clinical Trial
Oral topotecan given once or twice daily for ten days: a phase I pharmacology study in adult patients with solid tumors.
Prolonged exposure to topotecan (TPT) in in vitro experiments and in vivo studies in animals yielded the highest antitumor efficacy. An oral bioavailability of TPT of 32-44% enables convenient prolonged administration. Because of unpredictable diarrhea in the third week of the twice daily (b.i.d.) 21-day schedule of p.o. administered TPT and the finding of optimal down-regulation of topoisomerase I level after 10-14 days in mononuclear peripheral blood cells, a shorter period of administration (10 days) was chosen for Phase I and pharmacological studies of oral administration of TPT. ⋯ Significant correlations were observed between the myelotoxicity parameters and the area under the plasma concentration-time curve at day 1 of TPT lactone o.d. and b.i.d. The DLT of 10 daily administrations of oral topotecan every 3 weeks consisted of a combination of myelosuppression and diarrhea for both schedules studied. The recommended doses for Phase II studies are 1.4 mg/m2/day for 10 days for the o.d. administration and 0.7 mg/m2 for the b.i.d. schedule.
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Most human non-small cell lung cancer (NSCLC) cell lines are refractory to all-trans-retinoic acid (ATRA). Recently, N-(4-hydroxyphenyl)retinamide (4HPR) was found to induce apoptosis in various tumor cells. In this study, we compared and contrasted the effects of 4HPR and ATRA on the growth and apoptosis of 10 NSCLC cell lines and normal human bronchial epithelial (NHBE) cells. ⋯ ATRA inhibited the growth of the NHBE cells by 70-80%. 4HPR induced apoptosis in most of the cells, including the ATRA-resistant ones, as evidenced by a DNA fragmentation assay. No correlation was found between growth inhibition by 4HPR and the expression of retinoic acid receptor beta (determined by Northern blotting and PCR), p53, or Bcl-2 proteins (analyzed by Western blotting). These results demonstrate that 4HPR is more potent than ATRA in inducing apoptosis in NSCLC cells and suggest that further clinical trials for prevention and therapy of NSCLC using 4HPR are warranted.
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We tested the activity of dolastatin 10 (a natural product derived from the shell-less marine mollusk, Dolabella auricularia, a sea hare) and its structural modification, auristatin PE, alone and in combination with bryostatin 1 (a protein kinase C activator derived from the marine bryozoan Bugula neritina) on a human B-cell chronic lymphocytic leukemia cell line (WSU-CLL) and in a severe combined immune deficient (SCID) mouse xenograft model bearing this cell line. WSU-CLL cells were cultured in RPMI 1640 at a concentration of 2 x 10(5)/ml using a 24-well plate. Agents were added to triplicate wells, and cell count, viability, mitosis, and apoptosis were assessed after 24 h of incubation at 37 degrees C. ⋯ Dolastatin 10 + bryostatin 1-treated animals produced cure in only two of five mice. We conclude that: (a) auristatin-PE is more effective in this model than dolastatin 10; (b) auristatin PE can be administered at a concentration 10 times greater than dolastatin 10; (c) there is a synergetic effect between these agents and bryostatin 1, which is more apparent in the bryostatin 1 + auristatin PE combination. The use of these agents should be explored clinically in the treatment of CLL.