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Investigational New Drugs Aug 2015SB939 is a potent oral inhibitor of class 1, 2, and 4 histone deacetylases (HDACs). These three HDAC classes are highly expressed in castration resistant prostate cancer...
BACKGROUND
SB939 is a potent oral inhibitor of class 1, 2, and 4 histone deacetylases (HDACs). These three HDAC classes are highly expressed in castration resistant prostate cancer (CRPC) and associated with poor clinical outcomes. We designed a phase II study of SB939 in men with metastatic CRPC.
METHODS
Patients received SB939 60 mg on alternate days three times per week for 3 weeks on a 4-week cycle. Primary endpoints were PSA response rate (RR) and progression-free survival (PFS). Secondary endpoints included objective response rate and duration; overall survival; circulating tumor cell (CTC) enumeration and safety. Exploratory correlative studies of the TMPRSS2-ERG fusion and PTEN biomarkers were also performed.
RESULTS
Thirty-two patients were enrolled of whom 88 % had received no prior chemotherapy. The median number of SB939 cycles administered was three (range 1-8). Adverse events were generally grade 1-2, with five pts experiencing one or more grade three event. One patient died due to myocardial infarction. A confirmed PSA response was noted in two pts (6 %), lasting 3.0 and 21.6 months. In patients with measurable disease there were no objective responses. Six patients had stable disease lasting 1.7 to 8.0 months. CTC response (from ≥5 at baseline to <5 at 6 or 12 weeks) occurred in 9/14 evaluable patients (64 %).
CONCLUSION
Although SB939 was tolerable at the dose/schedule given, and showed declines in CTC in the majority of evaluable patients, it did not show sufficient activity based on PSA RR to warrant further study as a single agent in unselected patients with CRPC.
Topics: Aged; Aged, 80 and over; Antineoplastic Agents; Benzimidazoles; Disease-Free Survival; Histone Deacetylase Inhibitors; Humans; Kallikreins; Male; Middle Aged; Neoplastic Cells, Circulating; PTEN Phosphohydrolase; Prostate-Specific Antigen; Prostatic Neoplasms, Castration-Resistant; Serine Endopeptidases; Trans-Activators; Transcriptional Regulator ERG
PubMed: 25983041
DOI: 10.1007/s10637-015-0252-4 -
Annals of Oncology : Official Journal... May 2015A subgroup of sarcomas is characterized by defining chromosomal translocations, creating fusion transcription factor oncogenes. Resultant fusion oncoproteins associate...
BACKGROUND
A subgroup of sarcomas is characterized by defining chromosomal translocations, creating fusion transcription factor oncogenes. Resultant fusion oncoproteins associate with chromatin-modifying complexes containing histone deacetylases (HDAC), and lead to epigenetic transcriptional dysregulation. HDAC inhibitors were shown to be effective in vitro, reversing gene repression by these complexes, restoring PTEN expression and apoptosis via the PI3K/Akt/mTOR pathway.
PATIENTS AND METHODS
SB939 is an oral inhibitor of classes 1 and 2 HDAC. Eligible patients with recurrent or metastatic translocation-associated sarcoma (TAS) by local pathology were treated with 60 mg/day every other day for 3 of 4 weeks. Central pathology review was conducted with fusion oncogenes characterized, and HDAC2 expression correlated with efficacy in pre-specified methods.
RESULTS
Twenty-two patients were treated with a median of 2 cycles. Fourteen patients were assessable for response with confirmed specific chromosomal translocations; 8 had a best response of stable disease (SD) (median duration 5.4 months) with no confirmed objective responses. The 3-month progression-free survival (PFS) rate was 49%. Among those with HDAC2 score ≥5, 7/10 had SD, versus 0/3 with HDAC2 score <5. SB939 was considered as well tolerated with <10% patients experienced ≥grade 3 toxicity.
CONCLUSION
This study was stopped prematurely due to prolonged unavailability of SB939. No objective responses were seen. Although the observed SD in HDAC2 high patients was interesting, due to the small sample size, no definitive conclusion can be drawn about the efficacy of SB939 in this patient population.
CLINICAL TRIAL
NCT01112384.
Topics: Administration, Oral; Adult; Antineoplastic Agents; Benzimidazoles; Biomarkers, Tumor; Canada; Disease Progression; Disease-Free Survival; Drug Administration Schedule; Early Termination of Clinical Trials; Female; Histone Deacetylase 2; Histone Deacetylase Inhibitors; Humans; Male; Middle Aged; Neoplasm Recurrence, Local; Sarcoma; Time Factors; Translocation, Genetic; Treatment Outcome; Young Adult
PubMed: 25632070
DOI: 10.1093/annonc/mdv033 -
Leukemia Apr 2015Acute myeloid leukemia (AML) is the second most common form of leukemia and the most frequent cause of leukemia-related deaths in the United States. The incidence of AML... (Review)
Review
Acute myeloid leukemia (AML) is the second most common form of leukemia and the most frequent cause of leukemia-related deaths in the United States. The incidence of AML increases with advancing age and the prognosis for patients with AML worsens substantially with increasing age. Many older patients are ineligible for intensive treatment and require other therapeutic approaches to optimize clinical outcome. To address this treatment gap, novel agents with varying mechanisms of action targeting different cellular processes are currently in development. Hypomethylating agents (azacitidine, decitabine, SGI-110), histone deacetylase inhibitors (vorinostat, pracinostat, panobinostat), FMS-like tyrosine kinase receptor-3 inhibitors (quizartinib, sorafenib, midostaurin, crenolanib), cytotoxic agents (clofarabine, sapacitabine, vosaroxin), cell cycle inhibitors (barasertib, volasertib, rigosertib) and monoclonal antibodies (gentuzumab ozogamicin, lintuzumab-Ac225) represent some of these promising new treatments. This review provides an overview of novel agents that have either completed or are currently in ongoing phase III trials in patients with previously untreated AML for whom intensive treatment is not an option. Other potential drugs in earlier stages of development will also be addressed in this review.
Topics: Age Factors; Aged; Antibodies, Monoclonal; Antimetabolites, Antineoplastic; Antineoplastic Agents; Clinical Trials, Phase III as Topic; Cytotoxins; Drugs, Investigational; Histone Deacetylase Inhibitors; Humans; Leukemia, Myeloid, Acute; Patient Selection; Protein Kinase Inhibitors
PubMed: 25142817
DOI: 10.1038/leu.2014.244 -
Leukemia Research Aug 2014
Topics: Animals; Antineoplastic Agents; Benzimidazoles; Drug Discovery; Epigenesis, Genetic; Flavonoids; Histone Deacetylase Inhibitors; Humans; Leukemia, Myeloid, Acute; Orphan Drug Production; Piperidines; Protein Kinase Inhibitors; Pteridines; Terminology as Topic
PubMed: 24996975
DOI: 10.1016/j.leukres.2014.06.007 -
Pediatric Blood & Cancer Nov 2013Pracinostat (SB939) is a potent oral inhibitor of class 1, 2, and 4 histone deacetylases (HDAC). The adult recommended phase II dose (RP2D) is 60 mg po three times per...
A phase I study of histone deacetylase inhibitor, pracinostat (SB939), in pediatric patients with refractory solid tumors: IND203 a trial of the NCIC IND program/C17 pediatric phase I consortium.
BACKGROUND
Pracinostat (SB939) is a potent oral inhibitor of class 1, 2, and 4 histone deacetylases (HDAC). The adult recommended phase II dose (RP2D) is 60 mg po three times per week (t.i.w.) for 3 weeks every 4 weeks. This study assessed the toxicities and pharmacokinetics of pracinostat and determined the RP2D in children with refractory solid tumors.
METHODS
Pediatric patients with refractory solid tumors were treated with oral pracinostat t.i.w. for 3 consecutive weeks, followed by 1 week off dosing. Three dose levels-25, 35, and 45 mg/m(2) were evaluated using a standard 3 + 3 cohort design. Pharmacokinetic (PK) studies were optional.
RESULTS
Twelve patients were enrolled. The most common diagnosis was Ewing sarcoma. Most adverse events (AEs) were hematological with five (40%) patients experiencing grade 3 neutropenia. Non-hematological AEs were generally grade 1. No dose limiting toxicities occurred. More hematological and non-hematological AEs occurred at 45 mg/m(2) : Two of five patients experienced Grade 3 neutropenia and one each Grade 3 thrombocytopenia and leucopenia, Grade 1 fatigue and anorexia occurred in three. The RP2D was declared to be 45 mg/m(2) (comparable to an adult dose of 80 mg). One patient had a best response of stable disease (duration of 2.9 months). Three patients on 25 mg/m(2) and one each on 35 and 45 mg/m(2) participated in the PK study. No dose related changes in Cmax or AUC occurred.
CONCLUSIONS
Pracinostat is reasonably well tolerated in children with refractory solid tumors. The RP2D is 45 mg/m(2) .
Topics: Adolescent; Antineoplastic Agents; Benzimidazoles; Child; Child, Preschool; Dose-Response Relationship, Drug; Female; Histone Deacetylase Inhibitors; Humans; Infant; Male; Maximum Tolerated Dose; Neoplasms
PubMed: 23893953
DOI: 10.1002/pbc.24694 -
Cancer Cell International Apr 2013The use of imatinib, an ABL tyrosine kinase inhibitor, has led to a dramatic change in the management of BCR-ABL-positive leukemia patients. However, resistance to...
Activity of histone deacetylase inhibitors and an Aurora kinase inhibitor in BCR-ABL-expressing leukemia cells: Combination of HDAC and Aurora inhibitors in BCR-ABL-expressing cells.
BACKGROUND
The use of imatinib, an ABL tyrosine kinase inhibitor, has led to a dramatic change in the management of BCR-ABL-positive leukemia patients. However, resistance to imatinib mediated by mutations in the BCR-ABL domain has become a major problem in the treatment of these patients.
METHODS
In the present study, we examined the activity of histone deacetylase (HDAC) inhibitors in combination with an Aurora kinase inhibitor in BCR-ABL-expressing cells.
RESULTS
We found the HDAC inhibitors vorinostat and/or pracinostat (SB939) induced apoptosis in BCR-ABL-expressing cells. Additionally, HDAC inhibitors reduced levels of Aurora A and B protein. An Aurora kinase inhibitor, tozasertib (VX-680), inhibited growth, promoted pro-apoptotic activity, reduced the phosphorylation of BCR-ABL and Crk-L, and activated caspase-3 and poly (ADP-ribose) polymerase (PARP) in BCR-ABL-positive cells. Moreover, after treatment with tozasertib, HDAC protein expression was decreased. Combination of vorinostat or pracinostat with tozasertib had a synergistic inhibitory effect on the proliferation of T315I cells. Phosphorylation of Crk-L decreased, and PARP activation increased after treatment with vorinostat or pracinostat and tozasertib. Moreover, combination of vorinostat or pracinostat and tozasertib significantly increased the extent of apoptosis in primary chronic myeloid leukemia cells.
CONCLUSIONS
This study demonstrated that combination of HDAC and Aurora inhibitors was highly effective against BCR-ABL-expressing cells.
PubMed: 23556431
DOI: 10.1186/1475-2867-13-32 -
Blood Cancer Journal May 2012Acute myeloid leukemia (AML) is currently treated with aggressive chemotherapy that is not well tolerated in many elderly patients, hence the unmet medical need for...
Acute myeloid leukemia (AML) is currently treated with aggressive chemotherapy that is not well tolerated in many elderly patients, hence the unmet medical need for effective therapies with less toxicity and better tolerability. Inhibitors of FMS-like tyrosine kinase 3 (FLT3), JAK2 and histone deacetylase inhibitors (HDACi) have been tested in clinical studies, but showed only moderate single-agent activity. High efficacy of the HDACi pracinostat treating AML and synergy with the JAK2/FLT3 inhibitor pacritinib is demonstrated. Both compounds inhibit JAK-signal transducer and activator of transcription (STAT) signaling in AML cells with JAK2(V617F) mutations, but also diminish FLT3 signaling, particularly in FLT3-ITD (internal tandem duplication) cell lines. In vitro, this combination led to decreased cell proliferation and increased apoptosis. The synergy translated in vivo in two different AML models, the SET-2 megakaryoblastic AML mouse model carrying a JAK2(V617F) mutation, and the MOLM-13 model of FLT3-ITD-driven AML. Pracinostat and pacritinib in combination showed synergy on tumor growth, reduction of metastases and synergistically decreased JAK2 or FLT signaling, depending on the cellular context. In addition, several plasma cytokines/growth factors/chemokines triggered by the tumor growth were normalized, providing a rationale for combination therapy with an HDACi and a JAK2/FLT3 inhibitor for the treatment of AML patients, particularly those with FLT3 or JAK2 mutations.
PubMed: 22829971
DOI: 10.1038/bcj.2012.14 -
Antimicrobial Agents and Chemotherapy Jul 2012Histone deacetylase (HDAC) enzymes posttranslationally modify lysines on histone and nonhistone proteins and play crucial roles in epigenetic regulation and other...
Histone deacetylase (HDAC) enzymes posttranslationally modify lysines on histone and nonhistone proteins and play crucial roles in epigenetic regulation and other important cellular processes. HDAC inhibitors (e.g., suberoylanilide hydroxamic acid [SAHA; also known as vorinostat]) are used clinically to treat some cancers and are under investigation for use against many other diseases. Development of new HDAC inhibitors for noncancer indications has the potential to be accelerated by piggybacking onto cancer studies, as several HDAC inhibitors have undergone or are undergoing clinical trials. One such compound, SB939, is a new orally active hydroxamate-based HDAC inhibitor with an improved pharmacokinetic profile compared to that of SAHA. In this study, the in vitro and in vivo antiplasmodial activities of SB939 were investigated. SB939 was found to be a potent inhibitor of the growth of Plasmodium falciparum asexual-stage parasites in vitro (50% inhibitory concentration [IC(50)], 100 to 200 nM), causing hyperacetylation of parasite histone and nonhistone proteins. In combination with the aspartic protease inhibitor lopinavir, SB939 displayed additive activity. SB939 also potently inhibited the in vitro growth of exoerythrocytic-stage Plasmodium parasites in liver cells (IC(50), ~150 nM), suggesting that inhibitor targeting to multiple malaria parasite life cycle stages may be possible. In an experimental in vivo murine model of cerebral malaria, orally administered SB939 significantly inhibited P. berghei ANKA parasite growth, preventing development of cerebral malaria-like symptoms. These results identify SB939 as a potent new antimalarial HDAC inhibitor and underscore the potential of investigating next-generation anticancer HDAC inhibitors as prospective new drug leads for treatment of malaria.
Topics: Animals; Antimalarials; Antineoplastic Agents; Benzimidazoles; Cerebrum; Histone Deacetylase Inhibitors; Malaria; Mice; Plasmodium falciparum
PubMed: 22508312
DOI: 10.1128/AAC.00030-12 -
Leukemia Research Sep 2012Approximately half of the patients with myelofibrosis (MF) carry mutant JAK2(V617F) proteins. JAK2(V617F) has been recently shown to translocate to the nucleus and...
Approximately half of the patients with myelofibrosis (MF) carry mutant JAK2(V617F) proteins. JAK2(V617F) has been recently shown to translocate to the nucleus and modify specific histones, thus regulating transcription. We report on a phase II study testing the activity and tolerability of the histone deacetylase inhibitor pracinostat given at 60 mg every other day for three weeks per month in 22 patients with intermediate or high risk MF. Eight (36%) patients experienced clinical benefit, with 6 (27%) experiencing reductions in splenomegaly (median 3 cm, range 1-4 cm). According to International Working Group criteria, 2 (9%) patients had clinical improvement (anemia response in both cases). The most frequent side effect associated to pracinostat therapy was fatigue, which occurred in 20 (91%) patients (grade 2 in 3 patients). Grade 3-4 neutropenia, anemia, and thrombocytopenia occurred in 13%, 0%, and 21%, respectively. Twenty-one patients permanently discontinued pracinostat, mainly due to lack of efficacy. In conclusion, pracinostat at the dose tested is reasonably tolerated and has modest activity in patients with MF.
Topics: Aged; Benzimidazoles; Disease Progression; Female; Follow-Up Studies; Histone Deacetylase Inhibitors; Humans; Male; Middle Aged; Organ Size; Primary Myelofibrosis; Spleen; Splenomegaly; Treatment Outcome
PubMed: 22475363
DOI: 10.1016/j.leukres.2012.03.003 -
Drug Metabolism and Disposition: the... Dec 2011The preclinical absorption, distribution, metabolism, and excretion (ADME) properties of Pracinostat [(2E)-3-[2-butyl-1-[2-(diethylamino)...
The preclinical absorption, distribution, metabolism, and excretion (ADME) properties of Pracinostat [(2E)-3-[2-butyl-1-[2-(diethylamino) ethyl]-1H-benzimidazol-5-yl]-N-hydroxyarylamide hydrochloride; SB939], an orally active histone deacetylase inhibitor, were characterized and its human pharmacokinetics (PK) was predicted using Simcyp and allometric scaling. SB939 showed high aqueous solubility with high Caco-2 permeability. Metabolic stability was relatively higher in dog and human liver microsomes than in mouse and rat. The major metabolites formed in human liver microsomes were also observed in preclinical species. Human cytochrome P450 (P450) phenotyping showed that SB939 was primarily metabolized by CYP3A4 and CYP1A2. SB939 did not significantly inhibit human CYP3A4, 1A2, 2D6, and 2C9 (>25 μM) but inhibited 2C19 (IC(50) = 5.8 μM). No significant induction of human CYP3A4 and 1A2 was observed in hepatocytes. Plasma protein binding in mouse, rat, dog, and human ranged between ∼84 and 94%. The blood-to-plasma ratio was ∼1.0 in human blood. SB939 showed high systemic clearance (relative to liver blood flow) of 9.2, 4.5, and 1.5 l · h(-1) · kg(-1) and high volume of distribution at steady state (>0.6 l/kg) of 3.5, 1.7, and 4.2 l/kg in mouse, rat, and dog, respectively. The oral bioavailability was 34, 65, and ∼3% in mice, dogs, and rats, respectively. The predicted oral PK profile and parameters of SB939, using Simcyp and allometric scaling, were in good agreement with observed data in humans. Simcyp predictions showed lack of CYP3A4 and 2C19 drug-drug interaction potential for SB939. In summary, the preclinical ADME of SB939 supported its preclinical and clinical development as an oral drug candidate.
Topics: Administration, Oral; Animals; Benzimidazoles; Biological Availability; Caco-2 Cells; Chromatography, Liquid; Cytochrome P-450 Enzyme System; Dogs; Female; Histone Deacetylase Inhibitors; Humans; Male; Mice; Mice, Inbred BALB C; Microsomes, Liver; Rats; Rats, Wistar; Tandem Mass Spectrometry
PubMed: 21873472
DOI: 10.1124/dmd.111.041558