A phase I study of vorinostat (suberoylanilide hydroxamic acid, SAHA) in combination with 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) in patients with advanced colorectal cancer (CRC)

Abstract

3592 Background: Vorinostat is a novel histone deacetylase (HDAC) inhibitor that potentiates 5-FU and platinum antitumor activity. This potentiation is associated with ∼ 40 fold decrease in thymidilate synthase (TS) expression, the main target of 5-FU, in preclinical models. We conducted a phase I study of vorinostat plus FOLFOX in patients with CRC to determine the recommended dose of this combination. Methods: Vorinostat was escalated in a standard 3+3 design. FOLFOX was administered at a fixed dose every 2 weeks: leucovorin 400mg/m2 and oxaliplatin 85mg/m2 over 2 hours followed by 5-FU bolus 400mg/m2 and 5-FU infusion 2400mg/m2 over 46 hours. Vorinostat started 3 days prior to FOLFOX and was given twice daily for 1 week followed by 1 week break. Investigated dose levels of vorinostat (twice daily) include 100, 200, and 300 mg. Tumor biopsies were obtained from patients with accessible liver metastases before and on the 4th day of vorinostat (prior to FOLFOX) to assess TS expression. Results: 9 patients (pts) enrolled (M/F: 8/1; median age: 57, ECOG 0/1: 5/4). All pts had failed prior FOLFOX, irinotecan, and cetuximab therapy. One pt at dose level (DL) 1 was not evaluable due to rapid clinical progression. No dose-limiting toxicities were noted among the 8 evaluable pts. No grade (G) 3 toxicities were noted on the first cycle of treatment (within 2 weeks after 1st FOLFOX) and accrual continues on DL3. Cycle 1 toxicities were attributed to FOLFOX and consisted of 1 G2 neutropenia, 1 G2 mucositis, and 2 G2 nausea/vomiting. Responses were evaluable in 6 pts: 1 pt with peritoneal carcinomatosis on DL 1 has stable disease 5 months + along with a stable CEA; 3 patients at DL2 have stable disease at 2 months along with declining CEA in 2/3 pts. Two pts (DL1) with liver metastases biopsies had a major decrease in TS expression by IHC after 4 days of vorinostat. Conclusions: Vorinostat at 100–200mg PO BID × 1 week every 2 weeks in combination with FOLFOX is well tolerated. The lowest DL of 100 mg PO BID is associated with down-regulation of TS. Disease stabilization in highly refractory patients is promising. The investigation of this regimen in the first or second-line treatment of metastatic CRC is warranted. No significant financial relationships to disclose.