Bevacizumab, irinotecan, temozolomide, tyrosine kinase inhibition, and MEK inhibition are effective against pleomorphic xanthoastrocytoma regardless of V600E status.

INTRODUCTION: Pleomorphic xanthoastrocytoma (PXA) is a rare Grade II and III glioma. Surgical resection is the mainstay of treatment, however, adjuvant therapy is sometimes necessary. Given the rarity of PXA, chemotherapeutic efficacy data is limited. The importance of the BRAF V600E mutation in the context of MAP kinase pathway inhibition is unknown. The purpose of this study was to perform an in vivo screen of a variety to agents to determine efficacy against both V600E mutant and non-mutant PXA. METHODS: The efficacy of bevacizumab, temozolomide, lomustine (CCNU), irinotecan (CPT 11), a tyrosine kinase inhibitor (sorafenib), a selective MEK1/2 inhibitor (cobimetinib), and a BRAF inhibitor (vemurafenib) were assessed in two subcutaneous xenografts: D645 PXA (V600E-mutant) and D2363 PXA (V600E-non-mutant) (n = 5-10 mice). Select agents were also assessed in an intracranial model of D2363 PXA (n = 6-9). Subcutaneous tumor growth and survival were the endpoints. RESULTS: Temozolomide, bevacizumab, CPT 11, and sorafenib significantly inhibited subcutaneous tumor growth in both V600E-mutant and V600E-non-mutant models (P < 0.05). MEK inhibition (cobimetinib) but not BRAF inhibition (vemurafenib) also inhibited tumor growth regardless of V600E mutation (P < 0.05). Temozolomide, CPT 11, and bevacizumab also prolonged survival in a V600E-non-mutant intracranial model (median overall survival (OS) 68.5, 62.5, and 42.5 days, respectively) in contrast to controls (31.5 days, P < 0.001). CONCLUSIONS: These findings suggest that when adjuvant treatment is clinically indicated for PXA, temozolomide, CPT 11, or bevacizumab may be considered. Additionally, a trial of a MEK inhibitor or tyrosine kinase inhibitor could be considered for PXA regardless of V600E mutation status.

Sym004-induced EGFR elimination is associated with profound anti-tumor activity in EGFRvIII patient-derived glioblastoma models.

BACKGROUND: Sym004 is a mixture of two monoclonal antibodies (mAbs), futuximab and modotuximab, targeting non-overlapping epitopes on the epidermal growth factor receptor (EGFR). Previous studies have shown that Sym004 is more efficient at inducing internalization and degradation of EGFR than individual components, which translates into superior cancer cell inhibition. We investigated whether Sym004 induces removal of EGFRvIII and if this removal translates into tumor growth inhibition in hard-to-treat glioblastomas (GBMs) harboring the mutated, constitutively active EGFR variant III (EGFRvIII). METHODS: To address this question, we tested the effect of Sym004 versus cetuximab in eight patient-derived GBM xenograft models expressing either wild-type EGFR (EGFRwt) and/or mutant EGFRvIII. All models were tested as both subcutaneous and orthotopic intracranial xenograft models. RESULTS: In vitro studies demonstrated that Sym004 internalized and removed EGFRvIII more efficiently than mAbs, futuximab, modotuximab, and cetuximab. Removal of EGFRvIII by Sym004 translated into significant in vivo anti-tumor activity in all six EGFRvIII xenograft models. Furthermore, the anti-tumor activity of Sym004 in vivo was superior to that of its individual components, futuximab and modotuximab, suggesting a clear synergistic effect of the mAbs in the mixture. CONCLUSION: These results demonstrate the broad activity of Sym004 in patient-derived EGFRvIII-expressing GBM xenograft models and provide a clear rationale for clinical evaluation of Sym004 in EGFRvIII-positive adult GBM patients.

A cross sectional analysis from a single institution's experience of psychosocial distress and health-related quality of life in the primary brain tumor population.

Primary brain tumor patients experience high levels of distress. The purpose of this cross-sectional, retrospective study is to evaluate the level and different sources of psychosocial distress and how these pertain to health-related quality of life (HRQoL). The Primary and Recurrent Glioma registry at Duke's The Preston Robert Tisch Brain Tumor Center was queried retrospectively for demographic and clinical information on patients seen between December 2013 and February 2014. Data also included the National Comprehensive Cancer Network's Distress Thermometer (NCCN-DT), Functional Assessment of Cancer Therapy-Brain Cancer (FACT-Br), and Functional Assessment of Chronic Illness Therapy- Fatigue (FACIT-F). 829 subjects completed questionnaires. 54% were male; 96% completed the NCCN-DT; 33.3% had a DT score ≥4 (moderate/severe distress). Women reported DT ≥ 4 more often than men (38.6 vs 29.0%; p = 0.005). Patients within 1 year of diagnosis reported DT ≥ 4 more often than those 1+ years after diagnosis (38.8 vs 30.9%; p = 0.034). 73.0% reported physical problems; the most frequent being fatigue (43.2%) and memory/concentration (40.9%). 42.0% complained of emotional problems with worry (29.4%) and nervousness (22.4%) being the most common. Patients who reported at least one practical, family, emotional or physical problem had significantly lower HRQoL scores (p < 0.001). Primary brain tumor patients experience memory dysfunction, fatigue, nervousness, worry, and financial concerns, which have a negative effect on the patient's HRQoL. By identifying and addressing these stressors, it may be possible to improve patient HRQoL.

Initial testing of VS-4718, a novel inhibitor of focal adhesion kinase (FAK), against pediatric tumor models by the Pediatric Preclinical Testing Program.

VS-4718, a novel inhibitor of focal adhesion kinase (FAK), was tested against the Pediatric Preclinical Testing Program's (PPTP's) in vitro cell line panel and showed a median relative IC50 of 1.22 µM. VS-4718 was tested in vivo against the PPTP xenograft models using a dose of 50 mg/kg administered by the oral route twice daily for 21 days. VS-4718 induced significant differences in an event-free survival distribution compared with control in 18 of 36 of the evaluable solid tumor xenografts and in 0 of 8 acute lymphoblastic leukemia (ALL) xenografts, but no xenograft lines showed tumor regression. Future plans include further evaluation of the role of FAK inhibition in combination with ABL kinase inhibitors for Ph+ ALL.

Initial testing (stage 1) of the curaxin CBL0137 by the pediatric preclinical testing program.

BACKGROUND: CBL0137 is a novel drug that modulates FAcilitates Chromatin Transcription (FACT), resulting in simultaneous nuclear factor-κB suppression, heat shock factor 1 suppression and p53 activation. CBL0137 has demonstrated antitumor effects in animal models of several adult cancers and neuroblastoma. PROCEDURES: CBL0137 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations ranging from 1.0 nM to 10.0 µM and against the PPTP in vivo solid tumor xenograft and acute lymphocytic leukemia (ALL) panels at 50 mg/kg administered intravenously weekly for 4 weeks. RESULTS: The median relative IC50 (rIC50 ) value for the PPTP cell lines was 0.28 µM (range: 0.13-0.80 µM). There were no significant differences in rIC50 values by histotype. CBL0137 induced significant differences in event-free survival (EFS) distribution compared to control in 10 of 31 (32%) evaluable solid tumor xenografts and in eight of eight (100%) evaluable ALL xenografts. Significance differences in EFS distribution were observed in four of six osteosarcoma lines, three of three rhabdoid tumor lines and two of six rhabdomyosarcoma lines. No objective responses were observed among the solid tumor xenografts. For the ALL panel, one xenograft achieved complete response and four achieved partial response. CONCLUSIONS: The most consistent in vivo activity for CBL0137 was observed against ALL xenografts, with some solid tumor xenograft lines showing tumor growth delay. It will be important to relate the drug levels in mice at 50 mg/kg to those in humans at the recommended phase 2 dose.

Phosphorylation of Glutathione S-Transferase P1 (GSTP1) by Epidermal Growth Factor Receptor (EGFR) Promotes Formation of the GSTP1-c-Jun N-terminal kinase (JNK) Complex and Suppresses JNK Downstream Signaling and Apoptosis in Brain Tumor Cells.

Under normal physiologic conditions, the glutathione S-transferase P1 (GSTP1) protein exists intracellularly as a dimer in reversible equilibrium with its monomeric subunits. In the latter form, GSTP1 binds to the mitogen-activated protein kinase, JNK, and inhibits JNK downstream signaling. In tumor cells, which frequently are characterized by constitutively high GSTP1 expression, GSTP1 undergoes phosphorylation by epidermal growth factor receptor (EGFR) at tyrosine residues 3, 7, and 198. Here we report on the effect of this EGFR-dependent GSTP1 tyrosine phosphorylation on the interaction of GSTP1 with JNK, on the regulation of JNK downstream signaling by GSTP1, and on tumor cell survival. Using in vitro and in vivo growing human brain tumors, we show that tyrosine phosphorylation shifts the GSTP1 dimer-monomer equilibrium to the monomeric state and facilitates the formation of the GSTP1-JNK complex, in which JNK is functionally inhibited. Targeted mutagenesis and functional analysis demonstrated that the increased GSTP1 binding to JNK results from phosphorylation of the GSTP1 C-terminal Tyr-198 by EGFR and is associated with a >2.5-fold decrease in JNK downstream signaling and a significant suppression of both spontaneous and drug-induced apoptosis in the tumor cells. The findings define a novel mechanism of regulatory control of JNK signaling that is mediated by the EGFR/GSTP1 cross-talk and provides a survival advantage for tumors with activated EGFR and high GSTP1 expression. The results lay the foundation for a novel strategy of dual EGFR/GSTP1 for treating EGFR+ve, GSTP1 expressing GBMs.

Initial Testing of NSC 750854, a Novel Purine Analog, Against Pediatric Tumor Models by the Pediatric Preclinical Testing Program.

BACKGROUND: NSC 750854 is a purine analog with an antitumor activity profile distinctive from that of other anticancer purines. It has shown significant activity against adult cancer preclinical models. PROCEDURE: NSC 750854 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations from 1.0 nM to 10 µM and against the PPTP in vivo xenograft panels administered intraperitoneally at a dose of 5 mg/kg daily for 5 days repeated at day 15. RESULTS: The median relative IC50 (rIC50 ) value for the PPTP cell lines was 32 nM (range from 11 to 124 nM), with consistent cytotoxicity across all cell lines. Acute lymphoblastic leukemia (ALL) cell lines were more sensitive to NSC 750854 than non-ALL cell lines. NSC 750854 induced significant differences in EFS distribution compared to control in 31 of 35 (89%) solid tumor xenografts. It induced tumor growth inhibition meeting criteria for intermediate or high event free survival (EFS) T/C activity in 17 of 32 (53%) evaluable solid tumor xenografts (most consistently in the rhabdomyosarcoma panel). Objective responses were observed in 15 of 37 (41%) solid tumor xenografts and in all eight leukemia models with complete response (CR) or maintained complete response (MCR) in seven of eight leukemia models. CONCLUSIONS: NSC 750854 has a unique spectrum of antitumor activity compared with other agents tested by the PPTP as it induces regression in tumor models with limited sensitivity to most agents tested to date. Given the promising level of activity observed for NSC 750854 against PPTP preclinical models, further exploration of its mechanism of action is warranted.

Pharmacodynamic and genomic markers associated with response to the XPO1/CRM1 inhibitor selinexor (KPT-330): A report from the pediatric preclinical testing program.

BACKGROUND: Selinexor (KPT-330) is an inhibitor of the major nuclear export receptor, exportin 1 (XPO1, also termed chromosome region maintenance 1, CRM1) that has demonstrated activity in preclinical models and clinical activity against several solid and hematological cancers. PROCEDURES: Selinexor was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations from 1.0 nM to 10 µM and against the PPTP in vivo xenograft panels administered orally at a dose of 10 mg/kg thrice weekly for 4 weeks. RESULTS: Selinexor demonstrated cytotoxic activity in vitro, with a median relative IC50 value of 123 nM (range 13.0 nM to >10 µM). Selinexor induced significant differences in event-free survival (EFS) distribution in 29 of 38 (76%) of the evaluable solid tumor xenografts and in five of eight (63%) of the evaluable ALL xenografts. Objective responses (partial or complete responses, PR/CR) were observed for 4 of 38 solid tumor xenografts including Wilms tumor, medulloblastoma (n = 2), and ependymoma models. For the ALL panel, two of eight (25%) xenografts achieved either CR or maintained CR. Two responding xenografts had FBXW7 mutations at R465 and two had SMARCA4 mutations. Selinexor induced p53, p21, and cleaved PARP in several solid tumor models. CONCLUSIONS: Selinexor induced regression against several solid tumor and ALL xenografts and slowed tumor growth in a larger number of models. Pharmacodynamic effects for XPO1 inhibition were noted. Defining the relationship between selinexor systemic exposures in mice and humans will be important in assessing the clinical relevance of these results.

Initial Testing (Stage 1) of MK-8242-A Novel MDM2 Inhibitor-by the Pediatric Preclinical Testing Program.

BACKGROUND: MK-8242 is an inhibitor of MDM2 that stabilizes the tumor suppressor TP53 and induces growth arrest or apoptosis downstream of TP53 induction. PROCEDURES: MK-8242 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations from 1.0 nM to 10.0 µM and against the PPTP in vivo xenograft panels using oral gavage on Days 1-5 and Day 15-19 at a dose of 125 mg/kg (solid tumors) or 75 mg/kg (acute lymphoblastic leukemia [ALL] models). RESULTS: The median IC50 for MK-8242 was 0.07 µM for TP53 wild-type cell lines versus >10 µM for TP53 mutant cell lines. MK-8242 induced a twofold or greater delay in time to event in 10 of 17 (59%) of TP53 wild-type solid tumor xenografts, excluding osteosarcoma xenografts that have very low TP53 expression. Objective responses were observed in seven solid tumor xenografts representing multiple histotypes. For the systemic-disease ALL panel, among eight xenografts there were two complete responses (CRs) and six partial responses (PRs). Two additional MLL-rearranged xenografts (MV4;11 and RS4;11) grown subcutaneously showed maintained CR and PR, respectively. The expected pharmacodynamic responses to TP53 activation were observed in TP53 wild-type models treated with MK-8242. Pharmacokinetic analysis showed that MK-8242 drug exposure in SCID mice appears to exceed that was observed in adult phase 1 trials. CONCLUSIONS: MK-8242-induced tumor regressions across multiple solid tumor histotypes and induced CRs or PRs for most ALL xenografts. This activity was observed at MK-8242 drug exposures that appear to exceed those observed in human phase 1 trials.

Proteomic profiling of patient-derived glioblastoma xenografts identifies a subset with activated EGFR: implications for drug development.

The development of drugs to inhibit glioblastoma (GBM) growth requires reliable pre-clinical models. To date, proteomic level validation of widely used patient-derived glioblastoma xenografts (PDGX) has not been performed. In the present study, we characterized 20 PDGX models according to subtype classification based on The Cancer Genome Atlas criteria, TP53, PTEN, IDH 1/2, and TERT promoter genetic analysis, EGFR amplification status, and examined their proteomic profiles against those of their parent tumors. The 20 PDGXs belonged to three of four The Cancer Genome Atlas subtypes: eight classical, eight mesenchymal, and four proneural; none neural. Amplification of EGFR gene was observed in 9 of 20 xenografts, and of these, 3 harbored the EGFRvIII mutation. We then performed proteomic profiling of PDGX, analyzing expression/activity of several proteins including EGFR. Levels of EGFR phosphorylated at Y1068 vary considerably between PDGX samples, and this pattern was also seen in primary GBM. Partitioning of 20 PDGX into high (n = 5) and low (n = 15) groups identified a panel of proteins associated with high EGFR activity. Thus, PDGX with high EGFR activity represent an excellent pre-clinical model to develop therapies for a subset of GBM patients whose tumors are characterized by high EGFR activity. Further, the proteins found to be associated with high EGFR activity can be monitored to assess the effectiveness of targeting EGFR. The development of drugs to inhibit glioblastoma (GBM) growth requires reliable pre-clinical models. We validated proteomic profiles using patient-derived glioblastoma xenografts (PDGX), characterizing 20 PDGX models according to subtype classification based on The Cancer Genome Atlas (TCGA) criteria, TP53, PTEN, IDH 1/2, and TERT promoter genetic analysis, EGFR amplification status, and examined their proteomic profiles against those of their parent tumors. Proteins found to be associated with high EGFR activity represent potential biomarkers for GBM monitoring.

Initial testing (stage 1) of the PARP inhibitor BMN 673 by the pediatric preclinical testing program: PALB2 mutation predicts exceptional in vivo response to BMN 673.

BACKGROUND: BMN 673 is a potent inhibitor of poly-ADP ribose polymerase (PARP) that is in clinical testing with a primary focus on BRCA-mutated cancers. BMN 673 is active both through inhibiting PARP catalytic activity and by tightly trapping PARP to DNA at sites of single strand breaks. PROCEDURE: BMN 673 was tested in vitro at concentrations ranging from 0.1 nM to 1 µM and in vivo at a daily dose of 0.33 mg/kg administered orally twice daily (Mon-Fri) and once daily on weekends (solid tumors) for 28 days. RESULTS: The median relative IC50 (rIC50 ) concentration against the PPTP cell lines was 25.8 nM. The median rIC50 for the Ewing cell lines was lower than for the remaining cell lines (6.4 vs. 31.1 nM, respectively). In vivo BMN 673 induced statistically significant differences in EFS distribution in 17/43 (39.5%) xenograft models. Three objective regressions were observed: a complete response (CR) in a medulloblastoma line (BT-45), a maintained CR in a Wilms tumor line (KT-10), and a maintained CR in an ependymoma line (BT-41). BMN 673 maintained its high level of activity against KT-10 with a threefold reduction in dose. KT-10 possesses a truncating mutation in PALB2 analogous to PALB2 mutations associated with hereditary breast and ovarian cancer that abrogate homologous recombination (HR) repair. CONCLUSIONS: The PPTP results suggest that single agent BMN 673 may have limited clinical activity against pediatric cancers. Single agent activity is more likely for patients whose tumors have defects in HR repair.

Initial testing (stage 1) of BAL101553, a novel tubulin binding agent, by the pediatric preclinical testing program.

BAL101553 is a highly water soluble prodrug of BAL27862 that arrests tumor cell proliferation and induces cell death in cancer cells through disruption of the microtubule network. In vitro BAL27862 demonstrated potent activity, with the median relative IC50 (rIC50 ) of 13.8 nM (range 5.4-25.2 nM). The in vitro activity of BAL27862 against the PPTP cell lines is distinctive from that previously described for vincristine. BAL101553 induced significant differences in EFS distribution compared to control in 16 of 30 (53%) solid tumor xenografts and in two of four (67%) of the evaluable ALL xenografts. No objective responses were observed.

Reversing the Warburg effect as a treatment for glioblastoma.

Glioblastoma multiforme (GBM), like most cancers, possesses a unique bioenergetic state of aerobic glycolysis known as the Warburg effect. Here, we documented that methylene blue (MB) reverses the Warburg effect evidenced by the increasing of oxygen consumption and reduction of lactate production in GBM cell lines. MB decreases GBM cell proliferation and halts the cell cycle in S phase. Through activation of AMP-activated protein kinase, MB inactivates downstream acetyl-CoA carboxylase and decreases cyclin expression. Structure-activity relationship analysis demonstrated that toluidine blue O, an MB derivative with similar bioenergetic actions, exerts similar action in GBM cell proliferation. In contrast, two other MB derivatives, 2-chlorophenothiazine and promethazine, exert no effect on cellular bioenergetics and do not inhibit GBM cell proliferation. MB inhibits cell proliferation in both temozolomide-sensitive and -insensitive GBM cell lines. In a human GBM xenograft model, a single daily dosage of MB does not activate AMP-activated protein kinase signaling, and no tumor regression was observed. In summary, the current study provides the first in vitro proof of concept that reversal of Warburg effect might be a novel therapy for GBM.

Profiling Hsp90 differential expression and the molecular effects of the Hsp90 inhibitor IPI-504 in high-grade glioma models.

Retaspimycin hydrochloride (IPI-504), an Hsp90 (heat shock protein 90) inhibitor, has shown activity in multiple preclinical cancer models, such as lung, breast and ovarian cancers. However, its biological effects in gliomas and normal brain derived cellular populations remain unknown. In this study, we profiled the expression pattern of Hsp90α/ß mRNA in stable glioma cell lines, multiple glioma-derived primary cultures and human neural stem/progenitor cells. The effects of IPI-504 on cell proliferation, apoptosis, motility and expression of Hsp90 client proteins were evaluated in glioma cell lines. In vivo activity of IPI-504 was investigated in subcutaneous glioma xenografts. Our results showed Hsp90α and Hsp90ß expression levels to be patient-specific, higher in high-grade glioma-derived primary cells than in low-grade glioma-derived primary cells, and strongly correlated with CD133 expression and differentiation status of cells. Hsp90 inhibition by IPI-504 induced apoptosis, blocked migration and invasion, and significantly decreased epidermal growth factor receptor levels, mitogen-activated protein kinase and/or Akt activities, and secretion of vascular endothelial growth factor in glioma cell lines. In vivo study showed that IPI-504 could mildly attenuate tumor growth in immunocompromised mice. These findings suggest that targeting Hsp90 by IPI-504 has the potential to become an active therapeutic strategy in gliomas in a selective group of patients, but further research into combination therapies is still needed.

Initial testing (stage 1) of the Polo-like kinase inhibitor volasertib (BI 6727), by the Pediatric Preclinical Testing Program.

BACKGROUND: Volasertib (BI 6727) is a potent inhibitor of Polo-like kinase 1 (Plk1), that is overexpressed in several childhood cancers and cell lines. Because of its novel mechanism of action, volasertib was evaluated through the PPTP. PROCEDURES: Volasertib was tested against the PPTP in vitro cell line panel at concentrations from 0.1 nM to 1.0 µM and against the PPTP in vivo xenograft panels administered IV at a dose of 30 mg/kg (solid tumors) or 15 mg/kg (ALL models) using a q7dx3 schedule. RESULTS: In vitro volasertib demonstrated cytotoxic activity, with a median relative IC50 value of 14.1 nM, (range 6.0-135 nM). Volasertib induced significant differences in EFS in 19 of 32 (59%) of the evaluable solid tumor xenografts and in 2 of 4 (50%) of the evaluable ALL xenografts. Volasertib induced tumor growth inhibition meeting criteria for intermediate EFS T/C (>2) activity in 11 of 30 (37%) evaluable solid tumor xenografts, including neuroblastoma (4 of 6) and glioblastoma (2 of 3) panels, and 2 of 4 ALL models. Objective responses (CR's) were observed for 4 of 32 solid tumor (two neuroblastoma, one glioblastoma, and one rhabdomyosarcoma) and one of four ALL xenografts. CONCLUSIONS: Volasertib shows potent in vitro activity against the PPTP cell lines with no histotype selectivity. In vivo, volasertib induced regressions in several xenograft models. However, pharmacokinetic data suggest that mice tolerate higher systemic exposure to volasertib than humans, suggesting that the current results may over-estimate potential clinical efficacy against the childhood cancers studied.

Initial testing (stage 1) of the investigational mTOR kinase inhibitor MLN0128 by the pediatric preclinical testing program.

MLN0128 is an investigational small molecule ATP-competitive inhibitor of the serine/threonine kinase mTOR. MLN0128 was tested against the in vitro panel at concentrations ranging from 0.1 nM to 1 µM and against the PPTP in vivo panels at a dose of 1 mg/kg administered orally daily × 28. In vitro the median relative IC(50) concentration was 19 nM. In vivo MLN0128 induced significant differences in EFS in 24/31 (77%) solid tumor models, but 0/7 ALL xenografts. The modest activity observed for MLN0128 against the PPTP preclinical models is similar to that previously reported for another TOR kinase inhibitor.

Initial testing (stage 1) of the notch inhibitor PF-03084014, by the pediatric preclinical testing program.

PF-03084014, a γ-secretase inhibitor, was tested against the PPTP in vitro cell line panel (1.0 nM to 10 µM) and against the in vivo xenograft panels (administered orally twice daily on Days 1-7 and 15-21). PF-03084014 demonstrated limited in vitro activity, with no cell line achieving ≥50% inhibition. PF-03084014 induced significant differences in EFS distribution in 14 of 35 (40%) solid tumor xenografts, and 1 of 9 ALL xenografts (which lacked a NOTCH1 mutation), but objective responses were not observed. PF-03084014 demonstrated limited single agent activity in vitro and in vivo against the pediatric preclinical models studied.

Initial solid tumor testing (stage 1) of AZD1480, an inhibitor of Janus kinases 1 and 2 by the pediatric preclinical testing program.

BACKGROUND: AZD1480 is an ATP competitive inhibitor of Janus kinases 1 and 2 (JAK1, 2) that has been shown to inhibit the growth of solid tumor models. This agent was selected for testing the putative role of JAK/STAT signaling in the standard PPTP solid tumor models. PROCEDURES: AZD1480 was tested against the PPTP in vitro cell line panel at concentrations from 1.0 nM to 10 µM and against the PPTP in vivo solid tumor xenograft panels at (60 mg/kg once daily (SID) × 5) for three consecutive weeks. Additional studies evaluated 5 to 20 mg/kg BID × 5 with SID dosing at 7-30 mg/kg at weekends for three consecutive weeks. RESULTS: In vitro the median relative IC50 (rIC50 ) for the PPTP cell lines was 1.5 µM, with a range from 0.3 µM to 5.9 µM. The two cell lines with rIC50 values of 0.3 µM both had ALK activating genomic alterations. AZD1480 demonstrated statistically significant differences (P < 0.05) in EFS distribution compared to control in 89% of the solid tumor xenografts. AZD1480 induced intermediate (EFS T/C > 2) or high-level growth inhibition in 15 of 30 (50%) solid tumor xenografts. Tumor regressions were observed in three of six Wilms tumor models at doses that induced inhibition of Stat3(Y705) phosphorylation. CONCLUSIONS: AZD1480 demonstrated significant tumor growth inhibition against most PPTP solid tumor xenografts, similar to that observed for antiangiogenic agents tested by the PPTP. Tumor regressing activity was noted for Wilms tumor xenografts.

Initial testing (stage 1) of the histone deacetylase inhibitor, quisinostat (JNJ-26481585), by the Pediatric Preclinical Testing Program.

BACKGROUND: Quisinostat (JNJ-26481585) is a second-generation pyrimidyl-hydroxamic acid histone deacetylase (HDAC) inhibitor with high cellular potency towards Class I and II HDACs. Quisinostat was selected for clinical development as it showed prolonged pharmacodynamic effects in vivo and demonstrated improved single agent antitumoral efficacy compared to other analogs. PROCEDURES: Quisinostat was tested against the PPTP in vitro panel at concentrations ranging from 1.0 nM to 10 µM and was tested against the PPTP in vivo panels at a dose of 5 mg/kg (solid tumors) or 2.5 mg/kg (ALL models) administered intraperitoneally daily × 21. RESULTS: In vitro quisinostat demonstrated potent cytotoxic activity, with T/C% values approaching 0% for all of the cell lines at the highest concentration tested. The median relative IC50 value for the PPTP cell lines was 2.2 nM (range <1-19 nM). quisinostat induced significant differences in EFS distribution compared to control in 21 of 33 (64%) of the evaluable solid tumor xenografts and in 4 of 8 (50%) of the evaluable ALL xenografts. An objective response was observed in 1 of 33 solid tumor xenografts while for the ALL panel, two xenografts achieved complete response (CR) or maintained CR, and a third ALL xenograft achieved stable disease. CONCLUSIONS: Quisinostat demonstrated broad activity in vitro, and retarded growth in the majority of solid tumor xenografts studied. The most consistent in vivo activity signals observed were for the glioblastoma xenografts and T-cell ALL xenografts.