Fetterly, Gerald J.

4083 Background: Thymidylate synthase (TS) over-expression is associated with 5-FU resistance. Pre-clinical studies demonstrate that vorinostat down-regulates intra-tumor TS in a dose-dependent fashion and augments 5-FU antitumor activity in xenograft models. We conducted a phase I clinical trial of an intermittent schedule of QD x 3 vorinostat in combination with a fixed dose of fluorouracil (5-FU) and leucovorin (LV) in patients (pts) with refractory solid tumors. Methods: Vorinostat was escalated in a standard 3 x 3 design in combination with a fixed dose of 5-FU and LV (simplified de Gramont regimen, sFULV2). Vorinostat was given QD x 3 on an every-2-week cycle. sFULV2 started on day 2 of vorinostat and consisted of leucovorin 400 mg/m2 i.v. over 2 hrs followed by 5-FU 400 mg/m2 bolus and 5-FU 2400 mg/m2 over 46 hrs. Results: 24 pts were enrolled: Male/Female: 11/13; ECOG 0/1: 6/18; Age: median 60 (range 42–77) yrs. 21 pts had colorectal cancer (CRC), 1 had gastric, 1 had esophageal, and 1 had anal cancer. Vorinostat dose-levels (DL) were 600 mg, 800 mg, 1000 mg, 1200 mg, 1400 mg, 1700 mg, and 2000 mg. Dose-limiting toxicities (DLT), consisting of fatigue and hand-and-foot syndrome (H&F), were seen in 2 of 3 pts at the 2000 mg DL. None of the 6 pts at the 1700 mg DL had a DLT. Cycle 1 grade 3/4 toxicities consisted of thrombocytopenia, GI bleeding, fatigue, and H&F in 2 pts at the 2000 mg DL and a non-DLT G3 diarrhea (lasted <24 hrs) in 1 pt at the 1700 mg DL. Grade 2 nausea, fatigue, and anorexia were common; especially at DL ≥ 1700 mg. Antitumor activity was noted in pts with CRC despite prior refractoriness to 5-FU and failure to oxaliplatin, irinotecan, and cetuximab in all pts. 12/21 CRC pts had a confirmed SD (11) or PR (1). CRC pts had a median PFS of 4 months, a ≥ 6 months PFS rate of 43%, and a ≥ 8 months PFS rate of 33%. Conclusions: The maximum tolerated dose (MTD) of vorinostat in combination with sFULV2 is 1700 mg PO QD x 3 every 2 weeks. This combination is associated with considerable activity in pts with 5-FU-refractory CRC and warrants further investigation. An expanded MTD cohort is accruing to investigate 5-FU-vorinostat PK interaction and intra-tumor TS down-regulation. (This work was supported by a grant from CTEP and the ACS.) No significant financial relationships to disclose.

Abstract Background: Triple negative breast cancer (TNBC) patients have poorer prognosis and there remains a lack of novel targeted therapies for their treatment. PIM2 (Proviral Integrations of Moloney virus 2) belongs to a family of three kinases that have been implicated in the survival and progression of hematologic malignancies and solid tumors. PIM2 has been linked to epithelial to mesenchymal transition in TNBC, which can lead to metastasis and chemotherapeutic resistance. We hypothesized that PIM2 may present as a therapeutic target in TNBC. Materials and Methods: The study involved both in vitro and in vivo studies involving a novel PIM2 inhibitor JP11646 (obtained from Jasco Pharmaceuticals). TNBC cell lines MDA-MB-231 and BT-549 were obtained for our in vitro studies. Cell viability was evaluated using MTT assay. Western Blot assay was used to evaluate relative protein expression. For in vivo studies, female SCID mice were inoculated in the mammary fat pads with 1 × 106 MDA-MB-231 cells. When tumor volumes reached 100 mm3, the mice were treated with JP11646 at the dosage 15mg/kg intraperitoneally for 2 consecutive days weekly for total of 4 weeks as determined from previous experiments. Control animals received vehicle only. The mice were euthanized once tumors reached ∼1,700 mm3. Results: BT-549 cells treated in vitro with 3 different available PIM kinase inhibitors AZD 1208, LGB321 and JP12641 showed only modest reduction in cell viability. However, treatment of both MDA-MB-231 and BT-549 with JP 11646 demonstrated significant reduction in cell viability with IC50 ranging from 40 to 71.6 nM. Treatment with JP11646 demonstrated a novel mechanism of action resulting in downregulation of PIM2 in both cell lines. Treatment with JP11646, but not other PIM kinase inhibitors, resulted in activation of apoptosis as measured by cleaved PARP (cPARP) levels. Anti-PIM2 siRNA treatment but not treatment with non-specific PIM kinase inhibitor AZD1208 resulted in cPARP induction. Inhibition of proteolysis by bortezomib resulted in preservation of PIM2 and inhibition of apoptosis as demonstrated by decreased cPARP levels after treatment with JP11646. PIM2 over-expressing clone of MDA-MB-231 cells showed enhanced proliferation and migration properties both in vitro and in vivo.Treatment of mice with orthotopically implanted MDA-MB-231 tumors with JP 11646 resulted in significant reduction in the tumor growth (p=0.0019) and increased overall survival (p=0.018) as compared to control mice. Conclusions: PIM2 upregulation in TNBC cell line resulted in more aggressive phenotype. JP11646, through novel mechanism of action resulting in degradation of PIM2, showed robust activity in TNBC cell lines both in vitro and in vivo. Further correlative studies in tumors harvested from in vivo experiments are ongoing. These results encourage further exploration of use of JP11646 as a targeted agent in treatment of TNBC. Citation Format: Mehta R, Kothai Guruswamy Sangameswaran D, Bezbatchenko K, Moore J, Gil M, Khoury T, Baldino C, Caserta J, Fetterly, Jr. G, Lee K, Adjei A, Opyrchal M. Preclinical efficacy of the novel PIM2 kinase inhibitor, JP11646 in triple negative breast cancer models [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-11-10.

AbstractPurpose: We conducted a phase I clinical trial to determine the maximum tolerated dose (MTD) of daily or twice daily vorinostat × 3 days when combined with fixed doses of 5-fluorouracil (FU) and leucovorin every 2 weeks.Experimental Design: Vorinostat doses were escalated in a standard 3 × 3 phase I design. FU/leucovorin was started on day 2 of vorinostat and consisted of leucovorin 400 mg/m2 i.v. over 2 hours followed by FU 400 mg/m2 i.v. bolus and 2,400 mg/m2 over 46 hours (sLV5FU2).Results: Forty-three patients were enrolled. Grade 3 fatigue, and hand and foot syndrome were the dose-limiting toxicities (DLT) at the 2,000 mg vorinostat once-daily dose level. Grade 3 fatigue and mucositis were DLTs at the 800 mg vorinostat twice-daily dose level. None of six patients at the 1,700 mg once daily or six patients at the 600 mg twice daily dose levels had a DLT; those dose levels represent the MTD. Twenty-one of 38 patients with FU-refractory colorectal cancer had stable disease, and one had a partial response. Vorinostat maximum serum concentrations at the MTD exceeded concentrations associated with thymidylate synthase downregulation in vitro. No pharmacokinetic interactions were noted between vorinostat and FU.Conclusions: The MTD of vorinostat in combination with sLV5FU2 is 1,700 mg orally once daily × 3 or 600 mg orally twice daily × 3 days every 2 weeks. Clinical activity in refractory colorectal cancer supports further clinical development of this combination. Clin Cancer Res; 16(14); 3786–94. ©2010 AACR.