Phase 2 Study of Sorafenib, Valproic Acid, and Sildenafil in the Treatment of Recurrent High-Grade Glioma.

Here we report the results of a single-center phase 2 clinical trial combining sorafenib tosylate, valproic acid, and sildenafil for the treatment of patients with recurrent high-grade glioma (NCT01817751). Clinical toxicities were grade 1 and grade 2, with one grade 3 toxicity for maculopapular rash (6.4%). For all evaluable patients, the median progression-free survival was 3.65 months and overall survival (OS) 10.0 months. There was promising evidence showing clinical activity and benefit. In the 33 evaluable patients, low protein levels of the chaperone GRP78 (HSPA5) was significantly associated with a better OS (p < 0.0026). A correlation between the expression of PDGFRα and OS approached significance (p < 0.0728). Five patients presently have a mean OS of 73.6 months and remain alive. This is the first therapeutic intervention glioblastoma trial to significantly associate GRP78 expression to OS. Our data suggest that the combination of sorafenib tosylate, valproic acid, and sildenafil requires additional clinical development in the recurrent glioma population.

A phase 1 study of regorafenib and sildenafil in adults with advanced solid tumors.

The purpose of this study is to establish the recommended phase 2 dose for regorafenib in combination with sildenafil for patients with advanced solid tumors. Secondary outcomes included identification of antitumor effects of regorafenib and sildenafil, toxicity of the combination, determination of PDE5 expression in tumor samples, and the impact of sildenafil on the pharmacokinetics of regorafenib. This study was a phase 1, open-label single-arm dose-escalation trial using a 3 + 3 design. Additional patients were enrolled at the maximum tolerated dose (MTD) until a total of 12 patients were treated at the MTD. A total of 29 patients were treated in this study. The median duration of treatment was 8 weeks. The recommended phase 2 doses determined in this study are regorafenib 160 mg daily with sildenafil 100 mg daily. The most common toxicities included palmar-plantar erythrodysesthesia syndrome (20 patients, 69%) and hypophosphatemia (18 patients, 62%). Two patients (7%) experienced grade 4 lipase increase. Objective responses were not observed; however, 14 patients (48%) had a period of stable disease during the study. Stable disease for up to 12 months was observed in patients with ovarian cancer as well as up to 20 months for a patient with cervical cancer. The combination of regorafenib and sildenafil at the recommended phase 2 dose is safe and generally well tolerated. Disease control in patients with gynecologic malignancies was especially encouraging. Further evaluation of the combination of regorafenib and sildenafil in gynecologic malignancies is warranted. Clinical Trial Registration Number: NCT02466802.

Non-canonical role for the ataxia-telangiectasia-Rad3 pathway in STAT3 activation in human multiple myeloma cells.

PURPOSE: The goal of this study was to characterize the relationship between ATR and STAT3 interactions in human multiple myeloma (MM) cells. METHODS: Various MM cell lines, including IL-6-dependent cells were exposed to ATR inhibitors and effects on STAT3 Tyr705 and Ser727 were monitored by WB analysis and ImageStream analysis. Parallel studies examined induction of cell death, STAT3 DNA binding activity, and expression of STAT3 downstream targets (BCL-XL, MCL-1, c-MYC). Validation was obtained in ATR shRNA knock-down cells, and in cells ectopically expressing BCL-XL, MCL-1, or c-MYC. Analogous studies were performed in primary MM cells and in a MM xenograft model. RESULTS: Multiple pharmacologic ATR inhibitors inhibited STAT3 Tyr705 (but not Ser727) phosphorylation at low uM concentrations and down-regulated BCL-XL, MCL-1, c-MYC in association with cell death induction. Compatible results were observed in ATR shRNA knock-down cells. Cell death induced by ATR inhibitors was significantly attenuated in cells ectopically expressing constitutively active STAT3, BCL-XL, MCL-1, or c-MYC. Concordant results were observed in primary human MM cells and in an in vivo MM xenograft model. CONCLUSIONS: Collectively, these findings argue for a non-canonical role for the ATR kinase in STAT3 activation in MM cells, and suggest that STAT3 inactivation contributes to the lethal actions of ATR inhibitors in MM.

Phase 1 study of belinostat and adavosertib in patients with relapsed or refractory myeloid malignancies.

PURPOSE: Belinostat is an intravenous histone deacetylase inhibitor with approval for T-cell lymphomas. Adavosertib is a first in class oral Wee1 inhibitor. Preclinical studies of the combination demonstrated synergy in various human acute myeloid leukemia (AML) lines as well as AML xenograft mouse models. EXPERIMENTAL DESIGN: This was a phase 1 dose-escalation study of belinostat and adavosertib in patients with relapsed/refractory AML and myelodysplastic syndrome (MDS). Patients received both drugs on days 1-5 and 8-12 of a 21-day cycle. Safety and toxicity were monitored throughout the study. Plasma levels of both drugs were measured for pharmacokinetic analysis. Response was determined by standard criteria including bone marrow biopsy. RESULTS: Twenty patients were enrolled and treated at 4 dose levels. A grade 4 cytokine release syndrome at dose level 4 (adavosertib 225 mg/day; belinostat 1000 mg/m2) qualified as a dose-limiting toxicity event. The most common non-hematologic treatment-related adverse events were nausea, vomiting, diarrhea, dysgeusia, and fatigue. No responses were seen. The study was terminated prior to maximum tolerated dose/recommended phase 2 dose determination. CONCLUSIONS: The combination of belinostat and adavosertib at the tested dose levels was feasible but without efficacy signals in the relapsed/refractory MDS/AML population.

Dual mTORC1/2 Inhibition Synergistically Enhances AML Cell Death in Combination with the BCL2 Antagonist Venetoclax.

PURPOSE: Acute myelogenous leukemia (AML) is an aggressive disease with a poor outcome. We investigated mechanisms by which the anti-AML activity of ABT-199 (venetoclax) could be potentiated by dual mTORC1/TORC2 inhibition. EXPERIMENTAL DESIGN: Venetoclax/INK128 synergism was assessed in various AML cell lines and primary patient AML samples in vitro. AML cells overexpressing MCL-1, constitutively active AKT, BAK, and/or BAX knockout, and acquired venetoclax resistance were investigated to define mechanisms underlying interactions. The antileukemic efficacy of this regimen was also examined in xenograft and patient-derived xenograft (PDX) models. RESULTS: Combination treatment with venetoclax and INK128 (but not the mTORC1 inhibitor rapamycin) dramatically enhanced cell death in AML cell lines. Synergism was associated with p-AKT and p-4EBP1 downregulation and dependent upon MCL-1 downregulation and BAK/BAX upregulation as MCL-1 overexpression and BAX/BAK knockout abrogated cell death. Constitutive AKT activation opposed synergism between venetoclax and PI3K or AKT inhibitors, but not INK128. Combination treatment also synergistically induced cell death in venetoclax-resistant AML cells. Similar events occurred in primary patient-derived leukemia samples but not normal CD34+ cells. Finally, venetoclax and INK128 co-treatment displayed increased antileukemia effects in in vivo xenograft and PDX models. CONCLUSIONS: The venetoclax/INK128 regimen exerts significant antileukemic activity in various preclinical models through mechanisms involving MCL-1 downregulation and BAK/BAX activation, and offers potential advantages over PI3K or AKT inhibitors in cells with constitutive AKT activation. This regimen is active against primary and venetoclax-resistant AML cells, and in in vivo AML models. Further investigation of this strategy appears warranted.

Phase 1 study of belinostat (PXD-101) and bortezomib (Velcade, PS-341) in patients with relapsed or refractory acute leukemia and myelodysplastic syndrome.

We report the results of a phase 1 dose-escalation study of belinostat and bortezomib in adult patients with acute leukemia or MDS or CML with blast crisis. Thirty-eight patients received IV belinostat days 1-5 and 8-12 with IV bortezomib days 1, 4, 8, and 11 every 21 days. QTc prolongation was the only identified DLT. The RP2Ds were 1.3 mg/m2 bortezomib and 1000 mg/m2 belinostat. One patient with highly refractory MLL-ENL rearranged biphenotypic AML with multiple karyotypic aberrations had a complete pathologic and karyotypic response. One patient with post-MPN AML remained on study with stable disease (SD) for 32 cycles. Whole-exome sequencing revealed no aberrations in the first patient and a hyper-mutator genotype in the second. Eighteen patients had a best response of SD. We conclude that this treatment strategy is feasible but has limited activity in this population. Nevertheless, the factors that predict exceptional responses to this strategy warrant further investigation.

Correction: Synergistic interactions between PLK1 and HDAC inhibitors in non-Hodgkin's lymphoma cells occur in vitro and in vivo and proceed through multiple mechanisms.

[This corrects the article DOI: 10.18632/oncotarget.15649.].

Phase I Study of Sorafenib and Vorinostat in Advanced Hepatocellular Carcinoma.

OBJECTIVES: Preclinical data suggest histone deacetylase inhibitors improve the therapeutic index of sorafenib. A phase I study was initiated to establish the recommended phase 2 dose of sorafenib combined with vorinostat in patients with unresectable hepatocellular carcinoma. MATERIALS AND METHODS: Patients received vorinostat (200 to 400 mg by mouth once daily, 5 of 7 d) and sorafenib at standard or reduced doses (400 mg [cohort A] or 200 mg [cohort B] by mouth twice daily). Patients who received 14 days of vorinostat in cycle 1 were evaluable for dose-limiting toxicity (DLT). RESULTS: Sixteen patients were treated. Thirteen patients were evaluable for response. Three patients experienced DLTs, 2 in cohort A (grade [gr] 3 hypokalemia; gr 3 maculopapular rash) and 1 in cohort B (gr 3 hepatic failure; gr 3 hypophosphatemia; gr 4 thrombocytopenia). Eleven patients required dose reductions or omissions for non-DLTtoxicity. Ten patients (77%) had stable disease (SD). The median treatment duration was 4.7 months for response-evaluable patients. One patient with SD was on treatment for 29.9 months, and another patient, also with SD, was on treatment for 18.7 months. Another patient electively stopped therapy after 15 months and remains without evidence of progression 3 years later. CONCLUSIONS: Although some patients had durable disease control, the addition of vorinostat to sorafenib led to toxicities in most patients, requiring dose modifications that prevented determination of the recommended phase 2 dose. The combination is not recommended for further exploration with this vorinostat schedule in this patient population.

The Covalent CDK7 Inhibitor THZ1 Potently Induces Apoptosis in Multiple Myeloma Cells In Vitro and In Vivo.

PURPOSE: The goal of this study was to characterize the activity of the covalent CDK7 inhibitor THZ1 in multiple myeloma models. EXPERIMENTAL DESIGN: Multiple myeloma lines were exposed to varying THZ1 concentrations alone or with carfilzomib or ABT-199, after which apoptosis was monitored by flow cytometry, protein expression by Western blot analysis, mRNA by RT-PCR. Analogous studies were performed in cells ectopically expressing c-MYC, MCL-1, or BCL-XL, or CRISPER-Cas CDK7 sgRNA knockout. Primary multiple myeloma cells were exposed to THZ1 ± carfilzomib or ABT-199. In vivo effects of THZ1 were examined in a systemic U266 xenograft model. RESULTS: THZ1 markedly diminished multiple myeloma cell proliferation and survival despite bortezomib or stromal cell resistance in association with G2-M arrest, inactivation of CTD RNA Pol II, dephosphorylation of CDKs 7 as well as 1, 2, and 9, and MCL-1, BCL-xL, and c-MYC mRNA or protein downregulation. Ectopic MCL-1, c-MYC, or BCL-XL expression significantly protected cells from THZ1 lethality. Both THZ1 and CRISPR-Cas CDK7 knockout sharply diminished multiple myeloma cell proliferation and significantly increased carfilzomib and ABT-199 lethality. Parallel effects and interactions were observed in primary CD138+ (N = 22) or primitive multiple myeloma cells (CD138-/CD19+/CD20+/CD27+; N = 16). THZ1 administration [10 mg/kg i.p. twice daily (BID), 5 days/week] significantly improved survival in a systemic multiple myeloma xenograft model with minimal toxicity and induced similar events observed in vitro, for example, MCL-1 and c-MYC downregulation. CONCLUSIONS: THZ1 potently reduces multiple myeloma cell proliferation through transcriptional downregulation of MCL-1, BCL-XL, and c-MYC in vitro and in vivo. It warrants further attention as a therapeutic agent in multiple myeloma.

The IAP antagonist birinapant potentiates bortezomib anti-myeloma activity in vitro and in vivo.

BACKGROUND: Mechanisms by which Smac mimetics (SMs) interact with proteasome inhibitors (e.g., bortezomib) are largely unknown, particularly in multiple myeloma (MM), a disease in which bortezomib represents a mainstay of therapy. METHODS: Interactions between the clinically relevant IAP (inhibitor of apoptosis protein) antagonist birinapant (TL32711) and the proteasome inhibitor bortezomib were investigated in multiple myeloma (MM) cell lines and primary cells, as well as in vivo models. Induction of apoptosis and changes in gene and protein expression were monitored using MM cell lines and confirmed in primary MM cell populations. Genetically modified cells (e.g., exhibiting shRNA knockdown or ectopic expression) were employed to evaluate the functional significance of birinapant/bortezomib-induced changes in protein levels. A MM xenograft model was used to evaluate the in vivo activity of the birinapant/bortezomib regimen. RESULTS: Birinapant and bortezomib synergistically induced apoptosis in diverse cell lines, including bortezomib-resistant cells (PS-R). The regimen robustly downregulated cIAP1/2 but not the canonical NF-κB pathway, reflected by p65 phosphorylation and nuclear accumulation. In contrast, the bortezomib/birinapant regimen upregulated TRAF3, downregulated TRAF2, and diminished p52 processing and BCL-XL expression, consistent with disruption of the non-canonical NF-κB pathway. TRAF3 knockdown, ectopic TRAF2, or BCL-XL expression significantly diminished birinapant/bortezomib toxicity. The regimen sharply increased extrinsic apoptotic pathway activation, and cells expressing dominant-negative FADD or caspase-8 displayed markedly reduced birinapant/bortezomib sensitivity. Primary CD138+ (n = 43) and primitive MM populations (CD138-/19+/20+/27+; n = 31) but not normal CD34+ cells exhibited significantly enhanced toxicity with combined treatment (P < 0.0001). The regimen was also fully active in the presence of HS-5 stromal cells or growth factors (e.g., IL-6 and VEGF). Finally, the regimen was well tolerated and significantly increased survival (P < 0.05 and P < 0.001) compared to single agents in a MM xenograft model. Combined treatment also downregulated cIAP1/2 and p52 while increasing PARP cleavage in MM cells in vivo. CONCLUSIONS: Our data suggest that birinapant and bortezomib interact synergistically in MM cells, including those resistant to bortezomib, through inactivation of the non-canonical NF-κB and activation of the extrinsic apoptotic pathway both in vitro and in vivo. They also argue that a strategy combining cIAP antagonists and proteasome inhibitors warrants attention in MM.

Homoharringtonine interacts synergistically with bortezomib in NHL cells through MCL-1 and NOXA-dependent mechanisms.

BACKGROUND: Interactions between the protein synthesis inhibitor homoharringtonine (HHT) and the proteasome inhibitor bortezomib were investigated in DLBCL and mantle cell lymphoma cells (MCL). METHODS: Various DLBCL and MCL cells were exposed to HHT and bortezomib alone or together after which apoptosis and signaling pathway perturbations were monitored by flow cytometry and Western blot analysis. Xenograft mouse models were used to assess tumor growth and animal survival. RESULTS: HHT and bortezomib co-administration synergistically induced apoptosis in GC-, ABC- and double-hit DLBCL cells. Similar interactions were observed in MCL cells and in primary lymphoma cells. HHT/bortezomib co-administration diminished binding of MCL-1 to both BAK and NOXA. Knock-down of NOXA significantly diminished lethality whereas MCL-1 knock-down or ectopic NOXA expression increased cell death. Notably, HHT/bortezomib lethality was dramatically reduced in BAK knockout or knockdown cells. Finally, HHT/bortezomib co-administration significantly improved survival compared to single agents in GC- and ABC- xenograft models while exhibiting little toxicity. CONCLUSIONS: These findings indicate that HHT and bortezomib cooperate to kill DLBCL and MCL cells through a process involving MCL-1 down-regulation, NOXA up-regulation, and BAK activation. They also suggest that a strategy combining HHT with bortezomib warrants attention in DLBCL and MCL.

Randomized study of doxorubicin-based chemotherapy regimens, with and without sildenafil, with analysis of intermediate cardiac markers.

BACKGROUND: Doxorubicin chemotherapy is used across a range of adult and pediatric malignancies. Cardiac toxicity is common, and dysfunction develops over time in many patients. Biomarkers used for predicting late cardiac dysfunction following doxorubicin exposure have shown promise. Preclinical studies have demonstrated potential cardioprotective effects of sildenafil. METHODS: We sought to confirm the safety of adding sildenafil to doxorubicin-based chemotherapy and assess N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) and high sensitivity cardiac troponin I (hsTnI) as early markers of anthracycline-induced cardiotoxicity. We randomized 27 patients (ages 31-77, 92.3% female) receiving doxorubicin chemotherapy using a blocked randomization scheme with randomly permuted block sizes to receive standard chemotherapy alone or with the addition of sildenafil. The study was not blinded. Sildenafil was dosed at 100 mg by mouth daily during therapy; patients took sildenafil three times daily on the day of doxorubicin. Doxorubicin dosing and schedule were dependent on the treatment regimen. Echocardiography was obtained prior to initiation of treatment and routinely thereafter up to 4 years. NT-proBNP and hsTnI were obtained with each cycle before, 1-3 h after, and 24 h after doxorubicin. RESULTS: Fourteen patients were randomized to receive standard doxorubicin chemotherapy alone (14 treated and analyzed), while 13 patients were randomized to the experimental doxorubicin and sildenafil arm (10 treated and analyzed). No toxicity signal was seen with the addition of sildenafil to doxorubicin-based regimens. There was no statistical difference between the treatment arms in relation to the change of mean left ventricular ejection fraction (LVEF) between the first and last evaluation. In both arms, hsTnI levels increased over time; however, elevated hsTnI was not associated with declines in LVEF. CONCLUSION: Adding sildenafil was safe, but did not offer cardioprotection following doxorubicin treatment. Increases in hsTnI levels were observed over time, but elevations during therapy did not correlate with subsequent decreases in LVEF. TRIAL REGISTRATION: This clinical trial (NCT01375699) was registered at www.clinicaltrials.gov on June 17, 2011.

A Phase II Trial of Bortezomib and Vorinostat in Mantle Cell Lymphoma and Diffuse Large B-cell Lymphoma.

BACKGROUND: The proteasome inhibitor bortezomib has demonstrated marked preclinical activity when combined with the histone deacetylase inhibitor vorinostat in leukemia, multiple myeloma, and mantle cell lymphoma (MCL) cells. The present study evaluated the efficacy and safety of the combination in patients with relapsed or refractory MCL and diffuse large B-cell lymphoma (DLBCL). PATIENTS AND METHODS: The present multicenter, nonrandomized phase II trial used a Simon 2-stage design with 3 cohorts: cohort A, MCL with no previous bortezomib (including untreated MCL); cohort B, MCL with previous bortezomib; and cohort C, relapsed or refractory DLBCL with no previous bortezomib. Vorinostat (400 mg) was administered orally on days 1 to 5 and 8 to 12 before bortezomib (1.3 mg/m2), which was administered intravenously on days 1, 4, 8, and 11 of each 21-day cycle. RESULTS: For the 65 treated patients (22 in cohort A, 4 in cohort B, and 39 in cohort C), the overall response rate was 31.8%, 0%, and 7.7%, respectively. The median progression-free survival was 7.6 months for cohort A and 1.8 months for cohort C. In cohort A, 7 patients had a partial response (PRs), 5 had stable disease (SD), 7 had progressive disease (PD), 1 was not assessed, and 2 were not evaluable. In cohort B, 2 had SD and 2 had PD. In cohort C, 3 had a PR, 8 had SD, 23 had PD, and 5 were not assessed. Baseline NF-κB activation, measured as nuclear RelA by immunohistochemistry, did not correlate with clinical response. CONCLUSION: The combination of bortezomib and vorinostat is safe and has modest activity in MCL and limited activity in DLBCL.

Cotargeting BCL-2 and PI3K Induces BAX-Dependent Mitochondrial Apoptosis in AML Cells.

Inhibitors targeting BCL-2 apoptotic proteins have significant potential for the treatment of acute myeloid leukemia (AML); however, complete responses are observed in only 20% of patients, suggesting that targeting BCL-2 alone is insufficient to yield durable responses. Here, we assessed the efficacy of coadministration of the PI3K/mTOR inhibitor GDC-0980 or the p110ß-sparing PI3K inhibitor taselisib with the selective BCL-2 antagonist venetoclax in AML cells. Tetracycline-inducible downregulation of BCL-2 significantly sensitized MV4-11 and MOLM-13 AML cells to PI3K inhibition. Venetoclax/GDC-0980 coadministration induced rapid and pronounced BAX mitochondrial translocation, cytochrome c release, and apoptosis in various AML cell lines in association with AKT/mTOR inactivation and MCL-1 downregulation; ectopic expression of MCL-1 significantly protected cells from this regimen. Combined treatment was also effective against primary AML blasts from 17 patients, including those bearing various genetic abnormalities. Venetoclax/GDC-0980 markedly induced apoptosis in primitive CD34+/38-/123+ AML cell populations but not in normal hematopoietic progenitor CD34+ cells. The regimen was also active against AML cells displaying intrinsic or acquired venetoclax resistance or tumor microenvironment-associated resistance. Either combinatorial treatment markedly reduced AML growth and prolonged survival in a systemic AML xenograft mouse model and diminished AML growth in two patient-derived xenograft models. Venetoclax/GDC-0980 activity was partially diminished in BAK-/- cells and failed to induce apoptosis in BAX-/- and BAX-/-BAK-/- cells, whereas BIM-/- cells were fully sensitive. Similar results were observed with venetoclax alone in in vitro and in vivo systemic xenograft models. Collectively, these studies demonstrate that venetoclax/GDC-0980 exhibits potent anti-AML activity primarily through BAX and, to a lesser extent, BAK. These findings argue that dual BCL-2 and PI3K inhibition warrants further evaluation in AML.Significance: Combined treatment with clinically relevant PI3K and BCL-2 inhibitors may prove effective in the treatment of acute myeloid leukemia. Cancer Res; 78(11); 3075-86. ©2018 AACR.

Flavopiridol enhances ABT-199 sensitivity in unfavourable-risk multiple myeloma cells in vitro and in vivo.

BACKGROUND: The BCL-2-specific BH3-mimetic ABT-199 (venetoclax) has been reported to be principally active against favourable-risk multiple myeloma (MM) cells, prompting efforts to extend its activity to include more resistant, higher-risk MM subsets. METHODS: Effects of the CDK9 inhibitor flavopiridol (FP; alvocidib) on responses to ABT-199 were examined in MM cells. Cell death and protein expression were evaluated by western blot and immunofluorescence. Xenograft models were used to study combination effects in vivo. RESULTS: FP synergistically increased ABT-199 lethality in both ABT-199-sensitive and insensitive MM cells. FP blocked CDK9 activation/positive transcription elongation factor B phosphorylation, downregulated MCL-1, increased BCL-2/MCL-1 ratios, and upregulated BIM. MCL-1 ectopic expression or knockdown in MM cells significantly diminished or increased ABT-199 sensitivity, respectively. CDK9 knockdown triggered MCL-1 downregulation and increased ABT-199 activity, whereas BIM knockdown significantly reduced FP/ABT-199 lethality. FP also enhanced ABT-199 lethality in unfavourable prognosis primary MM cells. HS-5 cell co-culture failed to protect MM cells from the FP/ABT-199 regimen, suggesting circumvention of microenvironmental signals. Finally, FP/ABT-199 significantly increased survival in systemic xenograft and immune-competent MM models while exhibiting minimal toxicity. CONCLUSIONS: These findings argue that CDK9 inhibitors, for example, FP may increase the antimyeloma activity of ABT-199, including in unfavourable-risk MM minimally responsive to ABT-199 alone.

Synergistic interactions between PLK1 and HDAC inhibitors in non-Hodgkin's lymphoma cells occur in vitro and in vivo and proceed through multiple mechanisms.

Interactions between the polo-like kinase 1 (PLK1) inhibitor volasertib and the histone deacetylase inhibitor (HDACI) belinostat were examined in diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) cells in vitro and in vivo. Exposure of DLBCL cells to very low concentrations of volasertib in combination with belinostat synergistically increased cell death (apoptosis). Similar interactions occurred in GC-, ABC-, double-hit DLBCL cells, MCL cells, bortezomib-resistant cells and primary lymphoma cells. Co-exposure to volasertib/belinostat induced a marked increase in M-phase arrest, phospho-histone H3, mitotic errors, cell death in M-phase, and DNA damage. Belinostat diminished c-Myc mRNA and protein expression, an effect significantly enhanced by volasertib co-exposure. c-Myc knock-down increased DNA damage and cell death in response to volasertib, arguing that c-Myc down-regulation plays a functional role in the lethality of this regimen. Notably, PLK1 knock-down in DLBCL cells significantly increased belinostat-induced M-phase accumulation, phospho-histone H3, γH2AX, and cell death. Co-administration of volasertib and belinostat dramatically reduced tumor growth in an ABC-DLBCL flank model (U2932) and a systemic double-hit lymphoma model (OCI-Ly18), accompanied by a pronounced increase in survival without significant weight loss or other toxicities. Together, these findings indicate that PLK1/HDAC inhibition warrants attention as a therapeutic strategy in NHL.

A phase 1 study of bortezomib and romidepsin in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma, indolent B-cell lymphoma, peripheral T-cell lymphoma, or cutaneous T-cell lymphoma.

A phase 1 study was conducted to determine the dose-limiting toxicities and maximum-tolerated dose (MTD) for bortezomib followed by romidepsin on days 1, 8, and 15 in patients with relapsed/refractory CLL/SLL or B- or T-cell lymphoma. Eighteen treated patients were evaluable for response. The MTD was 1.3 mg/m2 bortezomib and 10 mg/m2 romidepsin; median treatment duration was 3 cycles at this dose. The dose-limiting toxicities were grade 3 fatigue, vomiting, and chills. Two patients had partial responses, one lasting >2 years, 8 had stable disease, and 8 had progressive disease. The median duration of stable disease was 3.5 cycles. Correlative studies examining expression of NF-кB, XIAP, Bcl-xL, and Bim yielded variable results. The safety profile was consistent with that reported for single-agent bortezomib and romidepsin. This regimen has modest activity in heavily pretreated patients with relapsed/refractory CLL or B- or T-cell lymphoma. NCT00963274.

Phase I study of pemetrexed with sorafenib in advanced solid tumors.

PURPOSE: To determine if combination treatment with pemetrexed and sorafenib is safe and tolerable in patients with advanced solid tumors. RESULTS: Thirty-seven patients were enrolled and 36 patients were treated (24 in cohort A; 12 in cohort B). The cohort A dose schedule resulted in problematic cumulative toxicity, while the cohort B dose schedule was found to be more tolerable. The maximum tolerated dose (MTD) was pemetrexed 750 mg/m2 every 14 days with oral sorafenib 400 mg given twice daily on days 1-5. Because dosing delays and modifications were associated with the MTD, the recommended phase II dose was declared to be pemetrexed 500 mg/m2 every 14 days with oral sorafenib 400 mg given twice daily on days 1-5. Thirty-three patients were evaluated for antitumor activity. One complete response and 4 partial responses were observed (15% overall response rate). Stable disease was seen in 15 patients (45%). Four patients had a continued response at 6 months, including 2 of 5 patients with triple-negative breast cancer. EXPERIMENTAL DESIGN: A phase I trial employing a standard 3 + 3 design was conducted in patients with advanced solid tumors. Cohort A involved a novel dose escalation schema exploring doses of pemetrexed every 14 days with continuous sorafenib. Cohort B involved a modified schedule of sorafenib dosing on days 1-5 of each 14-day pemetrexed cycle. Radiographic assessments were conducted every 8 weeks. CONCLUSIONS: Pemetrexed and intermittent sorafenib therapy is a safe and tolerable combination for patients, with promising activity seen in patients with breast cancer.

The NAE inhibitor pevonedistat interacts with the HDAC inhibitor belinostat to target AML cells by disrupting the DDR.

Two classes of novel agents, NEDD8-activating enzyme (NAE) and histone deacetylase (HDAC) inhibitors, have shown single-agent activity in acute myelogenous leukemia (AML)/myelodysplastic syndrome (MDS). Here we examined mechanisms underlying interactions between the NAE inhibitor pevonedistat (MLN4924) and the approved HDAC inhibitor belinostat in AML/MDS cells. MLN4924/belinostat coadministration synergistically induced AML cell apoptosis with or without p53 deficiency or FLT3-internal tandem duplication (ITD), whereas p53 short hairpin RNA (shRNA) knockdown or enforced FLT3-ITD expression significantly sensitized cells to the regimen. MLN4924 blocked belinostat-induced antiapoptotic gene expression through nuclear factor-κB inactivation. Each agent upregulated Bim, and Bim knockdown significantly attenuated apoptosis. Microarrays revealed distinct DNA damage response (DDR) genetic profiles between individual vs combined MLN4924/belinostat exposure. Whereas belinostat abrogated the MLN4924-activated intra-S checkpoint through Chk1 and Wee1 inhibition/downregulation, cotreatment downregulated multiple homologous recombination and nonhomologous end-joining repair proteins, triggering robust double-stranded breaks, chromatin pulverization, and apoptosis. Consistently, Chk1 or Wee1 shRNA knockdown significantly sensitized AML cells to MLN4924. MLN4924/belinostat displayed activity against primary AML or MDS cells, including those carrying next-generation sequencing-defined poor-prognostic cancer hotspot mutations, and CD34(+)/CD38(-)/CD123(+) populations, but not normal CD34(+) progenitors. Finally, combined treatment markedly reduced tumor burden and significantly prolonged animal survival (P < .0001) in AML xenograft models with negligible toxicity, accompanied by pharmacodynamic effects observed in vitro. Collectively, these findings argue that MLN4924 and belinostat interact synergistically by reciprocally disabling the DDR in AML/MDS cells. This strategy warrants further consideration in AML/MDS, particularly in disease with unfavorable genetic aberrations.

Phase 1 trial of carfilzomib (PR-171) in combination with vorinostat (SAHA) in patients with relapsed or refractory B-cell lymphomas.

A phase 1 study with carfilzomib and vorinostat was conducted in 20 B-cell lymphoma patients. Vorinostat was given orally twice daily on days 1, 2, 3, 8, 9, 10, 15, 16, and 17 followed by carfilzomib (given as a 30-min infusion) on days 1, 2, 8, 9, 15, and 16. A treatment cycle was 28 days. Dose escalation initially followed a standard 3 + 3 design, but adapted a more conservative accrual rule following dose de-escalation. The maximum tolerated dose was 20 mg/m2 carfilzomib and 100 mg vorinostat (twice daily). The dose-limiting toxicities were grade 3 pneumonitis, hyponatremia, and febrile neutropenia. One patient had a partial response and two patients had stable disease. Correlative studies showed a decrease in NF-κB activation and an increase in Bim levels in some patients, but these changes did not correlate with clinical response.