Paclitaxel, Carboplatin and Vorinostat for the Treatment of Advanced Stage Ovarian Carcinoma

Ovarian cancer is the fifth most common cancer in women, accounting for nearly 15,280 deaths annually in the United States [1]. Paclitaxel and Carboplatin are currently the accepted standard of care for first line treatment of ovarian cancer [2, 3]. In spite of standard chemotherapy, nearly 70% of patients succumb to this disease. Consequently, studies continue to examine the activity of new agents and dosing regimens to improve disease free intervals and overall survival.

There have been recent data suggesting that weekly chemotherapy regimens may significantly benefit cancer patients' prognosis [4, 5]. Non-small cell lung cancer patient studies employing weekly regimens have shown comparable response and survival rates to Q3 weekly dosing schedules, with a more favorable toxicity profile [6, 7]. Further studies have suggested that weekly Taxane dosing is at least as effective, less toxic, and more convenient than traditional regimens [4, 8, 9].

The favorable activity associated with weekly chemotherapy has primarily been studied in recurrent ovarian cancer patients, investigating the efficacy of single and/or combination drug regimens [10, 11]. However, there have been some studies involving chemo-naïve patients [4, 12, 13]. De Jongh et al. [4} conducted a randomized I/II ovarian cancer trial with cisplatin and escalating doses of weekly or 4-weekly paclitaxel. The chemo-naïve patients exhibited a 94% overall response rate and 48 month median overall survival, while maintaining manageable toxicity. In a more recent advanced ovarian cancer study, Isonishi et al. compared the impact of paclitaxel and carboplatin administered either tri-weekly (c-TC) or dose dense weekly (dd-TC) with regard to patient progression free survival (PFS) [14]. Median PFS for the c-TC patients was 17.1 months and 27.9 months for the dd-TC group. There was also more favorable survival rates in the dose dense patients (83.6%) in comparison to the tri-weekly groups (77.7%)

Shen et al. conducted a Chinese study investigating the efficacy of combination weekly Taxol plus Carboplatin compared to Taxol given every three weeks plus Carboplatin in previously untreated ovarian cancer patients [12]. While the two regimens had equal efficacy, there was less toxicity observed in the weekly regimen. Additional studies have also indicated that lower doses and shorter infusion times inherent in weekly dosing regimens should mitigate bone marrow myelosuppression and other toxicities associated with standard paclitaxel 3-weekly administration [13].

In addition to weekly primary induction chemotherapy regimens, studies involving consolidation or maintenance therapy have been employed in the hopes of improving survival [15, 16]. Micha et al. reported significantly better progression free survival results (94 weeks vs. 45 weeks) for an ovarian cancer group who received 12 cycles of paclitaxel consolidation therapy following induction therapy, compared to a similar group who received 3 cycles of paclitaxel consolidation therapy [16].

The current pilot study was designed to determine toxicity, progression free survival, and response rate of weekly Taxol; every four-week Carboplatin; and Vorinostat (7 days on, 7 days off 7 days on, 7 days off) given for 6 cycles. Some patients will continue on consolidation therapy, which will consist of Taxol in combination with Vorinostat for an additional 12 cycles.

Modifying the dosing schedule of established chemotherapy regimens using weekly chemotherapy administration and consolidation therapy may decrease drug toxicity and maximize efficacy. These benefits are particularly intriguing in patients for whom disease treatment is long-term.

Since no triplet regimen has demonstrated compelling superiority, the combination of Taxol, Carboplatin, and Vorinostat is intriguing because of their potential synergy, distinct mechanisms of action, and non-overlapping toxicity.