Hiroyuki Iwamura

Lack of cross‐resistance to FF‐10501, an inhibitor of inosine‐5′‐monophosphate dehydrogenase, in azacitidine‐resistant cell lines selected from SKM‐1 and MOLM‐13 leukemia cell lines

Resistance to azacitidine is a major issue in the treatments of myelodysplastic syndrome and acute myeloid leukemia, and previous studies suggest that changes in drug metabolism are involved in the resistance. Therefore, drugs with mechanisms resistant or alternative to such metabolic changes have been desired for the treatment of resistant disease. We generated azacitidine‐resistant cells derived from SKM‐1 and MOLM‐13 leukemia cell lines in vitro, analyzed the mechanisms, and examined the impact on the efficacy of other antimetabolic drugs. It appeared that the cell growth‐inhibitory effect of azacitidine, expression levels of uridine–cytidine kinase 2, and the concentrations of azacitidine triphosphate were remarkably decreased in the resistant cells compared with those in parent cells. These results were consistent with previous observations that azacitidine resistance is derived from metabolic changes. Cross‐resistance of greater than 10‐fold (shift in IC50 value) was observed in azacitidine‐resistant cells for decitabine and for cytarabine, but not for gemcitabine or the inosine‐5′‐monophosphate dehydrogenase (IMPDH) inhibitors FF‐10501 and mycophenolate mofetil (cross‐resistance to 5‐fluorouracil was cell line dependent). The IMPDH inhibitors maintained their cell growth‐inhibitory activities in the azacitidine‐resistant cell lines, in which the levels of adenine phosphoribosyltransferase (which converts FF‐10501 to its active form, FF‐10501 ribosylmonophosphate [FF‐10501RMP]), FF‐10501RMP, and the target enzyme, IMPDH, were equivalent to those in the parent cell lines. These results suggest that an IMPDH inhibitor such as FF‐10501 could be an alternative therapeutic treatment for leukemia patients with acquired resistance to azacitidine.

Preclinical activity of FF-10501-01, a novel inosine-5′-monophosphate dehydrogenase inhibitor, in acute myeloid leukemia

BACKGROUNDnFF-10501-01 is a selective inosine monophosphate dehydrogenase (IMPDH) inhibitor that has shown activity in cancer cell lines. We studied whether FF-10501-01 is effective in targeting a variety of hypomethylating agent (HMA)-sensitive and -resistant acute myelogenous leukemia (AML) cell lines.nnnMETHODSnWe treated multiple cell lines (including HMA-resistant cells) with FF-10501-01 and analyzed proliferation, apoptosis, and cell cycle status. We also assessed HMA-FF-10501-01 combinations and the ability of extracellular guanosine to rescue cell proliferation in FF-10501-01-treated cells. We performed high-performance liquid chromatography (HPLC) to study guanine nucleotide levels in treated and untreated cells. Finally, we studied the effects of FF-10501-01 in fresh peripheral blood cells taken from AML patients.nnnRESULTSnFF-10501-01 showed a strong dose-dependent effect on proliferation and induced apoptosis at approximately 30μM. The effects of FF-10501-01 treatment on cell cycle status were variable, with no statistically significant trends. Guanosine rescued proliferation in FF-10501-01-treated cells, and HPLC results showed significant decreases in phosphorylated guanosine levels in MOLM13 cells. FF-10501-01 effectively reduced proliferation at concentrations of 300μM and above in 3 primary AML samples.nnnCONCLUSIONSnFF-10501-01 effectively induces AML cell death and reduces AML peripheral blood cell proliferation by targeting guanine nucleotide biosynthesis regardless of HMA resistance status.

Abstract 5127: In vitro and in vivo evaluation of FF-10502-01, a new pyrimidine nucleoside analogue

Introduction:FF-10502-01 is a synthetic pyrimidine nucleoside analogue structurally similar to gemcitabine (gem) with a substitution of sulfur for oxygen in the pentose ring. The anti-tumor effects of FF-10502-01 were studied in solid tumor cell lines and human tumor xenograft models. Methods:10 human solid tumor cell lines were studied and included the following: 4 pancreatic (PANC) (BxPC-3, SUIT-2, Capan-1 and MIA PaCa-2), colon (HCT116), lung (NCI-H460), ovary (SK-OV-3), prostate (LNCap.FGC), breast (MDA-MB231) and mantle cell lymphoma (MCL) (Jeko-1). The effect of FF-10502-01 on DNA synthesis versus gem was evaluated in a PANC cell line (Capan-1). Tumor growth suppression was evaluated in human PANC xenograft models, SUIT-2 and Capan-1. FF-10502-01 or gem was administered at 240 or 480 mg/kg once a week starting 7d after orthotopic transplantation for 18 weeks, n=20/grp. Animals were followed for 128d after transplantation. Capan-1 was transplanted SC into nude mice (n=8/grp). FF-10502-01 or gem was administered at 120, 240, 360 or 480 mg/kg once weekly x 4 weeks 7d after transplantation. Tumor growth inhibitory effects were evaluated for 27d after starting treatment. FF-10502-01 single-dose pharmacokinetics (PK) were investigated in the mouse, rat and dog. Results:FF-10502-01 demonstrated in vitro activity against the PANC, colon, lung, ovarian, prostate and MCL cell lines, with IC 50 s of 30 – 330 nM. The activity was 1.5 – 15-fold lower than gem, however, FF-10502-01 demonstrated a 23-fold higher inhibition of DNA α-polymerase-mediated synthesis over gem. In the SUIT-2 orthotropic implant model, both gem and FF-10502-01 improved survival over vehicle controls. Med survival was not reached for the 480 mg/kg gem grp or either the 240 or 480 mg/kg FF-10502-01 grps. The survival rate was 5%, 25%, 75% for the vehicle, 240 and 480 mg/kg gem grps (p PK following single bolus IV doses indicated a similar PK profile to other pyrimidine nucleoside analogues, including gem. Conclusions:FF-10502-01 is a new pyrimidine nucleoside analogue with demonstrated preclinical efficacy against solid tumors and a potentially more tolerable safety profile than gem. Citation Format: Shinji Mima, Hiroki Nishikawa, Shinichi Watanabe, Tamami Higuchi, Takeaki Suzuki, Hiroyuki Iwamura, Chihaya Kakinuma, Takaaki Nakamura, Yasuhiro Shimada. In vitro and in vivo evaluation of FF-10502-01, a new pyrimidine nucleoside analogue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5127. doi:10.1158/1538-7445.AM2017-5127

Abstract 5148: Liposomal gemcitabine, FF-10832, improves gemcitabine (GEM) pharmacokinetics (PK) and increases anti-tumor efficacy

Introduction: FF-10832 is a liposome suspension optimized by Fujifilm nanotechnology containing 0.5 mg/mL GEM, cholesterol, HSPC, N-MPEG-DSPE. FF-10832 is expected to improve GEM PK and have strong anti-tumor effects. The PK and anti-tumor effects of FF-10832 were studied in mice and human pancreatic cancer xenograft models. Methods: Single-dose murine plasma PK of FF-10832 1 mg/kg was compared to GEM 240mg/kg. In vivo activity of GEM 240 mg/kg and FF-10832 1-5 mg/kg IV once weekly were compared in human pancreatic cancer murine xenograft models; 2 subcutaneous (Capan-1 [GEM-sensitive] and BxPC-3 [GEM-resistant]), and 1 orthotopic (SUIT-2) model. The active form of GEM (GEM triphosphate [dFdCTP]) inhibits DNA synthesis. dFdCTP tissue concentrations following FF-10832 4mg/kg and GEM 240mg/kg were compared in these models. Results: An extended plasma t ½ (10.6 vs. 2.9 hours), lower clearance, and smaller volume of distribution were observed with FF-10832 vs. GEM, which correlated with greater dose exposure achieved with FF-10832 compared to GEM (AUC last 186000 vs. 73000 hr·ng/mL). FF-10832 demonstrated increased in vivo activity in SUIT-2, Capan-1, and BxPC-3 models at significantly lower doses compared to GEM. In the Capan-1 and BxPC3 models, FF-10832 showed dose-dependent tumor growth suppression with FF-10832 4 mg/kg and 5 mg/kg superior to that of GEM (p Conclusions: FF-10832 is a stable liposomal GEM formulation demonstrating potent anti-tumor efficacy in solid tumor models with a favorable pharmacokinetic profile compared to non-liposomal GEM. Increased exposure achieved at lower GEM doses may potentially result in superior efficacy and a more tolerable safety profile for FF-10832 compared to non-liposomal GEM. Citation Format: Takeshi Matsumoto, Tsukasa Kitahashi, Takashi Komori, Hiromu Kitahara, Kohei Ono, Naoki Yamada, Hiroyuki Iwamura, Kiyohito Takada, Shinji Hagiwara, Yasuhiro Shimada. Liposomal gemcitabine, FF-10832, improves gemcitabine (GEM) pharmacokinetics (PK) and increases anti-tumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5148. doi:10.1158/1538-7445.AM2017-5148

Abstract 5112: Evaluation of FF-10502-01, a new pyrimidine nucleoside analogue, in pancreatic (PANC) patient-derived xenograft (PDX) models compared to gemcitabine and in combination with nab-paclitaxel

Introduction FF-10502-01 is a synthetic pyrimidine nucleoside analogue structurally similar to gem with a substitution of sulfur for oxygen in the pentose sugar. In previous studies, FF-10502-01 demonstrated preclinical efficacy across multiple solid tumors, including PANC cancer. In this study, we investigated the anti-tumor effect of FF-10502-01 in PANC PDX models. Methods 10 PANC PDX tumors were sourced from primary (2) or metastatic sites (8). 7 demonstrated high resistance (HR) to gem, 1 intermediate, and 2 low. In the dose-finding study, 3 PDX models were studied in 9 grps of NOD-SCID mice (n=10/grp), treated with 240 or 480 mg/kg FF-10502-01, 3 or 6 mg/kg nab-pac or 240 mg/kg gem, alone and in combination for 28d, followed by 28d observation. The definitive study consisted of 7 PDX models. 6 grps (n=10/grp) were treated with 240 or 480 mg/kg FF-10502-01, 6 mg/kg nab-pac or 240 mg/kg gem, alone and/or in combination for 28d, followed by 28d observation. After subcutaneous transplantation, animals were left undisturbed for 7d. Animals were monitored weekly and tumor volume measured with calipers. Average tumor volume (mm3) for each group at randomization into treatment grps ranged from 184.34 – 199.51 (SD ± 20.94 – 30.40). Statistical significance was determined using one-way ANOVA and Tukey’s test. Results At clinically relevant doses, FF-10502-01, alone and in combination with nab-pac demonstrated greater tumor growth suppression than vehicle-treated animals (p≤0.0001). In 7 models, FF-10502-01/nab-pac demonstrated higher tumor growth suppression than gem/nab-pac (p≤0.5, p≤0.01 or p≤0.001), irrespective of resistance to gem. In 3 models, there was no difference, but these models were highly responsive to gem/nab-pac, thus minimizing the effects of FF-10502-01/nab-pac. Despite statistical insignificance, FF-10502-01/nab-pac still demonstrated greater tumor growth inhibitory activity to gem/nab-pac. In HR gem models, FF-10502-01 was superior to gem (p≤0.0001, p≤0.001, p≤0.05) in 3 of 7, and FF-10502-01/nab-pac was superior to gem/nab-pac in 6 of 7 (p nab-pac (p≤0.0001, p≤0.0001, p≤0.01, p≤0.05). FF-10502-01/nab-pac also was more tolerable than gemcitabine/nab-pac, as demonstrated by less weight loss. Conclusions FF-10502-01 is a new pyrimidine nucleoside analogue with demonstrated preclinical efficacy in solid tumors, including PANC cancer. In PANC PDX models, FF-10502-01 alone and in combination with nab-pac demonstrated higher efficacy and better tolerability than gem alone or gem/nab-pac. FF-10502-01 is in Phase 1 clinical development. Citation Format: Takeaki Suzuki, Linda J. Paradiso, Jill Ricono, Jonathan Nakashima, Yoshihide Iwaki, Shinji Mima, Takayuki Yamada, Chihaya Kakinuma, Hiroyuki Iwamura, Shinichi Watanabe. Evaluation of FF-10502-01, a new pyrimidine nucleoside analogue, in pancreatic (PANC) patient-derived xenograft (PDX) models compared to gemcitabine and in combination with nab-paclitaxel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5112. doi:10.1158/1538-7445.AM2017-5112