PubMed · 7865002
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R J Wells. 1995. Phase II window therapy.. https://doi.org/10.1200/jco.1995.13.1.302
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Gemcitabine (2',2'-difluorodeoxycytidine, dFdC) and etoposide (4'-demethylepipodo-phyllo-toxin-9-4,6-O-ethylidene-beta-D-g lucopyranoside, VP-16) are antineoplastic agents with clinical activity against various types of solid tumors. Because of the low toxicity profile of dFdC and the differences in mechanisms of cytotoxicity, combinations of both drugs were studied in vitro. For this purpose, we used the human ovarian cancer cell line A2780, its cis-diammine-dichloroplatinum-resistant and VP-16 cross-resistant variant ADDP, and two non-small cell lung cancer cell lines, Lewis Lung (LL, murine) and H322 (human). The interaction between the drugs was determined with the multiple drug effect analysis (fixed molar ratio) and with a variable drug ratio. In the LL cell line, the combination of dFdC and VP-16 at a constant molar ratio (dFdC:VP-16 = 1:4 or 1:0.125 after 4- or 24-hr exposure, respectively) was synergistic (combination index [CI], calculated at 50% growth inhibition = 0.7 and 0.8, respectively; CI <1 indicating synergism). After 24- and 72-hr exposure to both drugs at a constant ratio, additivity was found in the A2780, ADDP, and H322 cell lines (dFdC:VP-16 = 1:500 for both exposure times in these cell lines). When cells were exposed to a combination of dFdC and VP-16 for 24 or 72 hr, with VP-16 at its IC25 and dFdC in a concentration range, additivity was found in both the LL and H322 cells; synergism was observed in the A2780 and ADDP cells, which are the least sensitive to VP-16. Schedule dependency was found in the LL cell line; when cells were exposed to dFdC 4 hr prior to VP-16 (constant molar ratio, total exposure 24 hr), synergism was found (CI = 0.5), whereas additivity was found when cells were exposed to VP-16 prior to dFdC (CI = 1.6). The mechanism of interaction between the drugs was studied in more detail in the LL cell line; dFdCTP accumulation was 1.2-fold enhanced by co-incubation with VP-16, and was even more pronounced (1.4-fold) when cells were exposed to VP-16 prior to dFdC. dCTP levels were decreased by VP-16 alone as well as by the combination of both compounds, which may favor phosphorylation of dFdC, thereby increasing dFdCTP accumulation. DNA strand break (DSB) formation was increased for exposure to both compounds together compared to exposure to each compound separately, this effect being most pronounced when cells were exposed to VP-16 prior to dFdC (38% and 0% DSB for dFdC and VP-16 alone, respectively and 97% DSB for the combination). The potentiation in DSB formation might be a result of the inhibition of DNA repair by dFdC. Provided the right schedule is used, VP-16 is certainly a compound eligible for combination with dFdC.
OBJECTIVE: To determine whether the treatment known as Di Bella multitherapy exerts antitumour activity worthy of further controlled clinical evaluation. DESIGN: 11 independent multicentre uncontrolled phase II trials relevant to 8 different types of cancer. SETTING: 26 Italian hospitals specialising in cancer treatment. SUBJECTS: 386 patients with advanced cancer were enrolled in the trials between March and July 1998 and followed to 31 October 1998. INTERVENTIONS: Melatonin, bromocriptine, either somatostatin or octreotide, and retinoid solution, the drugs that constitute Di Bella multitherapy, were given to patients daily. Cyclophosphamide and hydroxyurea were added in some trials. MAIN OUTCOME MEASURES: Responses were assessed every 1, 2, or 3 months, depending on the specific trial, and toxicity was evaluated using criteria developed by the World Health Organisation. RESULTS: No patient showed complete remission. Three patients showed partial remission: 1 of the 32 patients with non-Hodgkin's lymphoma; 1 of the 33 patients with breast cancer; and 1 of the 29 patients with pancreatic cancer. At the second examination, 12% (47) of the patients had stable disease; 52% (199) progressed; and 25% (97) died. CONCLUSIONS: Di Bella multitherapy did not show sufficient efficacy in patients with advanced cancer to warrant further clinical testing.
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