Faculty Bibliography

PURPOSE: PS-341 is a novel dipeptide boronic acid proteasome inhibitor with in vitro and in vivo antitumor activity that induces mechanisms of apoptosis by unknown mechanisms. EXPERIMENTAL DESIGN: Human non-small cell lung cancer cell lines were used to investigate effects PS-341 on cell proliferation, cell cycle progression, and the induction of apoptosis. RESULTS: PS-341 was 38-360-fold more cytotoxic against H460 cells when compared with the proteasome inhibitors MG-132 and PSI. Differential PS-341 cytotoxic effects were found with respect to P53 function: H322 cells (p53 mutant) were 6-fold less sensitive as compared with H460 cells (p53 wild type); and H358 cells (p53 null) were 1.6-fold more sensitive as compared with H460 cells (p53 wild type). A concentration- and time-dependent cell cycle blockade at G(2)-M phase was seen for H460 cells without any direct effects on microtubule polymerization or depolymerization. PS-341 exposure in H460 cells led to stabilization of p53, induction of p21(cip/waf-1) and MDM2 expression, an increase in cyclin B and cyclin A, and the activation of cyclin B and cyclin A kinases. MDM2 induction was found only in H460 cells, whereas in H322 and H358 cells, G(2)-M-phase arrest, p21(cip/waf-1) induction, and an increase in cyclin B1 were found. The commitment of G(2)-M-phase cells to apoptosis was verified by the activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase in drug-free medium. CONCLUSIONS: Our data suggest that the PS-341-induced G(2)-M-phase arrest may be associated with the inhibition of degradation of cell cycle regulators and that the up-regulation of p21(cip/waf-1) expression may be via p53-dependent and/or -independent pathways. The resulting disturbance of cell cycle progression leads either to growth inhibition or to the initiation of apoptotic pathways

Anti-tubulin couplets have activity in hormone-resistant prostate cancer. This study was designed to define the dose-limiting toxicity (DLT) and recommended phase II dose (RPTD) of the unique triplet combination of paclitaxel, estramustine phosphate (EMP) and vinorelbine (Pacl-E-Vin). Patients with advanced malignancies who had failed standard therapy, ECOG performance status (PS 0-2) and adequate organ function were included. Dose of EMP was fixed at 300 mg/m /dose p.o. t.i.d. on days 1-3 and 8-10. Vinorelbine dose was 20 mg/m /day i.v. on days 3 and 10. Paclitaxel was dose escalated from 40 to 50 mg/m /day i.v. on days 3 and 10. Cycles were repeated every 3 weeks. Twelve adults (median age 72) were entered on this study. Primary tumors included prostate ( =7), cervix ( =2), melanoma ( =1), colon (1) and lung with synchronous prostate cancer ( =1). Nine patients had received no prior chemotherapy, one had received a prior regimen and two had received two or more prior regimens. Of four evaluable patients at dose level 1, one patient had grade 3 neutropenia leading to the day 10 dose being withheld. Of five evaluable patients at dose level 2, there was one DLT (febrile neutropenia) and two grade 3 neutropenias leading to the day 10 dose being withheld. One patient had a lower extremity deep vein thrombosis. Other side effects were mild and reversible. Nine patients were evaluable for efficacy: three with prostate cancer had a greater than 50% prostate-specific antigen (PSA) response, and a patient with synchronous prostate and lung cancer had a greater than 50% PSA response. We conclude that the DLT of Pacl-E-Vin is neutropenia. RPTD is vinorelbine 20 mg/m, paclitaxel 40 mg/m, both administered on days 3 and 10, and EMP 900 mg/m /day on days 1-3 and 8-10, q3w. Dose omission at day 10 followed by 20% dose reduction of paclitaxel and vinorelbine is recommended in the event of grade 3 neutropenia. Activity in hormone-refractory prostate cancer is promising and warrants phase II evaluation

Although three large phase III trials have documented the benefit of IP chemotherapy, this therapy as consolidation has been studied in only a few pilot studies. These small studies have included patients with a variety of baseline prognostic characteristics, and only one series had a comparator group of surgically documented pathologic complete response to uniform systemic chemotherapy. No randomized trials have been done to assess the impact of IP consolidation on progression-free survival or survival in either positively or negatively reassessed patients. It is hoped that the current experience will trigger further consideration of future phase III trials to assess the value of IP consolidation after initial induction with chemotherapy (ie, chemical debulking)

The survival at 5 years, of patients with ovarian cancer, has steadily improved since 1960, when surgery and alkylating agents were the only initial modalities employed to cope with the usual late presentation of the disease. In the 1980s, cisplatin and then carboplatin became established as the most active drugs, alone or in combination with other drugs. In the last decade, the antimicrotubulin drug paclitaxel, and the topoisomerase I inhibitor topotecan were noted to be active after failure of platinum drugs. These drugs, as well as others with known activity in the second-line setting, such as the pegylated liposomal doxorubicin, gemcitabine and oral etoposide, all play a role in the treatment of these patients and likely prolong survival without eradicating the disease. The plight of these patients has stimulated new areas of drug development. Here, the evolution of the current therapeutic strategy, the scientific rationale for cytotoxic and non-cytotoxic agents and their status at present are reviewed. 'Targeted' drug trials, in contrast to trials studying cytotoxic drug analogues, currently represent only a minor portion of clinical trials in ovarian cancer

First-line chemotherapy for ovarian cancer during the past decade has evolved toward the use of carboplatin and paclitaxel combinations. This has been based on randomized trials showing that combinations of these two drugs lead to a outcome similar to that obtained using cisplatin and paclitaxel (that had, in turn, proven superior in progression-free survival and overall survival to cisplatin and cyclophosphamide) but with less toxicity. Surprisingly, taxane-platinum combinations were not superior to control arms in two studies (ICON3 and GOG-132) utilizing carboplatin or cisplatin as the comparators. This has renewed interest in the role of single agents in first-line chemotherapy - a concept also supported by a number of prior clinical trials with single-agent platinum compounds yielding results not inferior to combinations. Early 'pre-emptive' crossover (prior to the stipulated clinical progression) to paclitaxel or a paclitaxel-containing regimen, however, occurred in 24% of patients initially treated with cisplatin on GOG-132. This has led to the interpretation of this trial as a combination versus sequential design. Although not subscribing to this interpretation, the results of GOG-132 and ICON3 not only raise doubts over a clear superiority of combinations over single agents but also lead to a consideration of sequential treatment designs for first line. Advantages of such designs are: (a) ability to provide 'dose-dense' platinums followed by 'dose-dense' paclitaxel and, perhaps, other drugs; and (b) the potential of acquiring biological data linked to the antitumor effects of a specific drug. Mathematical modeling and recent positive results in breast cancer adjuvant therapy support the use of 'dose-dense' strategies, and these should be considered in the design of future trials in ovarian cancer