Human monocytes undergo functional re-programming during sepsis mediated by hypoxia-inducible factor-1α.

Sepsis is characterized by a dysregulated inflammatory response to infection. Despite studies in mice, the cellular and molecular basis of human sepsis remains unclear and effective therapies are lacking. Blood monocytes serve as the first line of host defense and are equipped to recognize and respond to infection by triggering an immune-inflammatory response. However, the response of these cells in human sepsis and their contribution to sepsis pathogenesis is poorly understood. To investigate this, we performed a transcriptomic, functional, and mechanistic analysis of blood monocytes from patients during sepsis and after recovery. Our results revealed the functional plasticity of monocytes during human sepsis, wherein they transited from a pro-inflammatory to an immunosuppressive phenotype, while enhancing protective functions like phagocytosis, anti-microbial activity, and tissue remodeling. Mechanistically, hypoxia inducible factor-1α (HIF1α) mediated this functional re-programming of monocytes, revealing a potential mechanism for their therapeutic targeting to regulate human sepsis.

Overall Survival with Durvalumab after Chemoradiotherapy in Stage III NSCLC.

BACKGROUND: An earlier analysis in this phase 3 trial showed that durvalumab significantly prolonged progression-free survival, as compared with placebo, among patients with stage III, unresectable non-small-cell lung cancer (NSCLC) who did not have disease progression after concurrent chemoradiotherapy. Here we report the results for the second primary end point of overall survival. METHODS: We randomly assigned patients, in a 2:1 ratio, to receive durvalumab intravenously, at a dose of 10 mg per kilogram of body weight, or matching placebo every 2 weeks for up to 12 months. Randomization occurred 1 to 42 days after the patients had received chemoradiotherapy and was stratified according to age, sex, and smoking history. The primary end points were progression-free survival (as assessed by blinded independent central review) and overall survival. Secondary end points included the time to death or distant metastasis, the time to second progression, and safety. RESULTS: Of the 713 patients who underwent randomization, 709 received the assigned intervention (473 patients received durvalumab and 236 received placebo). As of March 22, 2018, the median follow-up was 25.2 months. The 24-month overall survival rate was 66.3% (95% confidence interval [CI], 61.7 to 70.4) in the durvalumab group, as compared with 55.6% (95% CI, 48.9 to 61.8) in the placebo group (two-sided P=0.005). Durvalumab significantly prolonged overall survival, as compared with placebo (stratified hazard ratio for death, 0.68; 99.73% CI, 0.47 to 0.997; P=0.0025). Updated analyses regarding progression-free survival were similar to those previously reported, with a median duration of 17.2 months in the durvalumab group and 5.6 months in the placebo group (stratified hazard ratio for disease progression or death, 0.51; 95% CI, 0.41 to 0.63). The median time to death or distant metastasis was 28.3 months in the durvalumab group and 16.2 months in the placebo group (stratified hazard ratio, 0.53; 95% CI, 0.41 to 0.68). A total of 30.5% of the patients in the durvalumab group and 26.1% of those in the placebo group had grade 3 or 4 adverse events of any cause; 15.4% and 9.8% of the patients, respectively, discontinued the trial regimen because of adverse events. CONCLUSIONS: Durvalumab therapy resulted in significantly longer overall survival than placebo. No new safety signals were identified. (Funded by AstraZeneca; PACIFIC ClinicalTrials.gov number, NCT02125461 .).

Durvalumab after Chemoradiotherapy in Stage III Non-Small-Cell Lung Cancer.

BACKGROUND: Most patients with locally advanced, unresectable, non-small-cell lung cancer (NSCLC) have disease progression despite definitive chemoradiotherapy (chemotherapy plus concurrent radiation therapy). This phase 3 study compared the anti-programmed death ligand 1 antibody durvalumab as consolidation therapy with placebo in patients with stage III NSCLC who did not have disease progression after two or more cycles of platinum-based chemoradiotherapy. METHODS: We randomly assigned patients, in a 2:1 ratio, to receive durvalumab (at a dose of 10 mg per kilogram of body weight intravenously) or placebo every 2 weeks for up to 12 months. The study drug was administered 1 to 42 days after the patients had received chemoradiotherapy. The coprimary end points were progression-free survival (as assessed by means of blinded independent central review) and overall survival (unplanned for the interim analysis). Secondary end points included 12-month and 18-month progression-free survival rates, the objective response rate, the duration of response, the time to death or distant metastasis, and safety. RESULTS: Of 713 patients who underwent randomization, 709 received consolidation therapy (473 received durvalumab and 236 received placebo). The median progression-free survival from randomization was 16.8 months (95% confidence interval [CI], 13.0 to 18.1) with durvalumab versus 5.6 months (95% CI, 4.6 to 7.8) with placebo (stratified hazard ratio for disease progression or death, 0.52; 95% CI, 0.42 to 0.65; P<0.001); the 12-month progression-free survival rate was 55.9% versus 35.3%, and the 18-month progression-free survival rate was 44.2% versus 27.0%. The response rate was higher with durvalumab than with placebo (28.4% vs. 16.0%; P<0.001), and the median duration of response was longer (72.8% vs. 46.8% of the patients had an ongoing response at 18 months). The median time to death or distant metastasis was longer with durvalumab than with placebo (23.2 months vs. 14.6 months; P<0.001). Grade 3 or 4 adverse events occurred in 29.9% of the patients who received durvalumab and 26.1% of those who received placebo; the most common adverse event of grade 3 or 4 was pneumonia (4.4% and 3.8%, respectively). A total of 15.4% of patients in the durvalumab group and 9.8% of those in the placebo group discontinued the study drug because of adverse events. CONCLUSIONS: Progression-free survival was significantly longer with durvalumab than with placebo. The secondary end points also favored durvalumab, and safety was similar between the groups. (Funded by AstraZeneca; PACIFIC ClinicalTrials.gov number, NCT02125461 .).

SUPREME-HN: a retrospective biomarker study assessing the prognostic value of PD-L1 expression in patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck.

BACKGROUND: Programmed cell death ligand-1 (PD-L1) expression on tumor cells (TCs) is associated with improved survival in patients with head and neck squamous cell carcinoma (HNSCC) treated with immunotherapy, although its role as a prognostic factor is controversial. This study investigates whether tumoral expression of PD-L1 is a prognostic marker in patients with recurrent and/or metastatic (R/M) HNSCC treated with standard chemotherapy. METHODS: This retrospective, multicenter, noninterventional study assessed PD-L1 expression on archival R/M HNSCC tissue samples using the VENTANA PD-L1 (SP263) Assay. PD-L1 high was defined as PD-L1 staining of ≥ 25% TC, with exploratory scoring at TC ≥ 10% and TC ≥ 50%. The primary objective of this study was to estimate the prognostic value of PD-L1 status in terms of overall survival (OS) in patients with R/M HNSCC. RESULTS: 412 patients (median age, 62.0 years; 79.9% male; 88.2% Caucasian) were included from 19 sites in seven countries. 132 patients (32.0%) had TC ≥ 25% PD-L1 expression; 199 patients (48.3%) and 85 patients (20.6%) had TC ≥ 10% and ≥ 50%, respectively. OS did not differ significantly across PD-L1 expression (at TC ≥ 25% cutoff median OS: 8.2 months vs TC < 25%, 10.1 months, P = 0.55) or the ≥ 10% and ≥ 50% cutoffs (at TC ≥ 10%, median OS: 9.6 months vs TC < 10%, 9.4 months, P = 0.32, and at TC ≥ 50%, median OS 7.9 vs TC < 50%, 10.0 months, P = 0.39, respectively). CONCLUSIONS: PD-L1 expression, assessed using the VENTANA PD-L1 (SP263) Assay, was not prognostic of OS in patients with R/M HNSCC treated with standard of care chemotherapies. Trial registration ClinicalTrials.gov, NCT02543476. Registered September 4, 2015.

NADPH oxidase 1 supports proliferation of colon cancer cells by modulating reactive oxygen species-dependent signal transduction.

Reactive oxygen species (ROS) play a critical role in cell signaling and proliferation. NADPH oxidase 1 (NOX1), a membrane-bound flavin dehydrogenase that generates O2̇̄, is highly expressed in colon cancer. To investigate the role that NOX1 plays in colon cancer growth, we used shRNA to decrease NOX1 expression stably in HT-29 human colon cancer cells. The 80-90% decrease in NOX1 expression achieved by RNAi produced a significant decline in ROS production and a G1/S block that translated into a 2-3-fold increase in tumor cell doubling time without increased apoptosis. The block at the G1/S checkpoint was associated with a significant decrease in cyclin D1 expression and profound inhibition of mitogen-activated protein kinase (MAPK) signaling. Decreased steady-state MAPK phosphorylation occurred concomitant with a significant increase in protein phosphatase activity for two colon cancer cell lines in which NOX1 expression was knocked down by RNAi. Diminished NOX1 expression also contributed to decreased growth, blood vessel density, and VEGF and hypoxia-inducible factor 1α (HIF-1α) expression in HT-29 xenografts initiated from NOX1 knockdown cells. Microarray analysis, supplemented by real-time PCR and Western blotting, revealed that the expression of critical regulators of cell proliferation and angiogenesis, including c-MYC, c-MYB, and VEGF, were down-regulated in association with a decline in hypoxic HIF-1α protein expression downstream of silenced NOX1 in both colon cancer cell lines and xenografts. These studies suggest a role for NOX1 in maintaining the proliferative phenotype of some colon cancers and the potential of NOX1 as a therapeutic target in this disease.

Weekly EZN-2208 (PEGylated SN-38) in combination with bevacizumab in patients with refractory solid tumors.

BACKGROUND: Anti-angiogenic therapies such as bevacizumab upregulate hypoxia-inducible factor-1α (HIF-1α), a possible mechanism of drug resistance. Camptothecin analogues, including SN-38, have been shown to reduce the expression and transcriptional activity of HIF-1α in preclinical models. We hypothesized that co-administration of pegylated SN-38 (EZN-2208) may offset the induction of HIF-1α following bevacizumab treatment, resulting in synergistic antitumor effects. PATIENTS AND METHODS: Patients with refractory solid tumors were enrolled. Objectives were to evaluate the modulation of HIF-1α protein and target genes in tumor biopsies following administration of the combination of EZN-2208 administered weekly × 3 (days 1, 8, 15) and bevacizumab administered every 2 weeks, in 28-day cycles, and to establish the safety and tolerability of the combination. Tumor biopsies and dynamic contrast enhanced MRI (DCE-MRI) were obtained following bevacizumab alone (before EZN-2208) and after administration of both study drugs. RESULTS: Twelve patients were enrolled; ten were evaluable for response. Prolonged stable disease was observed in 2 patients, one with HCC (16 cycles) and another with desmoplastic round cell tumor (7 cycles). Reduction in HIF-1α protein levels in tumor biopsies compared to baseline was observed in 5 of 7 patients. Quantitative analysis of DCE-MRI from 2 patients revealed changes in K(trans) and k(ep). The study closed prematurely as further clinical development of EZN-2208 was suspended by the pharmaceutical sponsor. CONCLUSION: Preliminary proof-of-concept for modulation of HIF-1α protein in tumor biopsies following administration of EZN-2208 was observed. Two of 10 patients had prolonged disease stabilization following treatment with the EZN-2208 and bevacizumab combination.

Hypoxia: jump-starting inflammation.

Tissue hypoxia affects immunity and inflammation; however, the way in which changes in oxygen levels may modulate dendritic cell (DC) function is still not clear. Bosco et al report the gene expression profiling of hypoxic mature DCs and identify TREM-1 as a novel hypoxia-inducible gene that may amplify inflammatory responses.

Association of PD-L1 Expression on Tumor and Immune Cells with Survival in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma and Assay Validation.

Programmed cell death ligand-1 (PD-L1), expressed on both tumor cells (TC) and tumor-associated immune cells (IC), has been shown to be a useful biomarker and predictive of response to anti-PD-L1 agents in certain tumor types. In recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC), there is a growing interest in the role of PD-L1 expression on ICs, as well as TCs, for predicting response to immune checkpoint inhibitors. Using pooled data from the phase II HAWK and CONDOR studies, we investigated the association of baseline PD-L1 expression with durvalumab efficacy in patients with R/M HNSCC. To determine an optimal PD-L1 cut-off point for predicting survival, we assessed PD-L1 expression levels at different TC and IC cut-off points in patients treated with durvalumab. Longer survival was associated with higher TC membrane PD-L1 expression and IC staining. When the combined TC/IC algorithm was applied, a cut-off point for PD-L1 expression of ≥50% on TCs or ≥25% on ICs (TC ≥ 50%/IC ≥ 25%) showed a higher objective response rate (17.2% vs. 8.8%), longer median progression-free survival (2.8 vs. 1.9 months), and longer median overall survival (8.4 vs. 5.4 months) in the PD-L1-high versus PD-L1-low/negative patient populations, respectively. A scoring algorithm combining PD-L1 expression on TCs and ICs using the cut-off point TC ≥ 50%/IC ≥ 25% was optimal for identifying patients with HNSCC most likely to benefit from durvalumab treatment. The new algorithm is robust and can be reproducibly scored by trained pathologists. Significance: A novel algorithm for PD-L1 expression using the cut-off point TC ≥ 50%/IC ≥ 25% is robust for identifying patients with HNSCC most likely to benefit from durvalumab treatment and can be reproducibly scored by trained pathologists.

Curative-Intent Treatment with Durvalumab in Early-Stage Cancers.

The introduction of immunotherapy has fundamentally transformed the treatment landscape in cancer, providing long-term survival benefit for patients with advanced disease across multiple tumor types, including non-small cell lung cancer (NSCLC). In the placebo-controlled phase 3 PACIFIC trial, the PD-L1 inhibitor durvalumab demonstrated significant improvements in progression-free survival and overall survival in patients with unresectable, stage III NSCLC who had not progressed after platinum-based chemoradiotherapy (CRT). These findings have led to the widespread acceptance of the 'PACIFIC regimen' (durvalumab after CRT) as the standard of care in this setting. Moreover, the PACIFIC trial is the first study to demonstrate a proven survival advantage with an immunotherapy in a curative-intent setting, thereby providing a strong rationale for further investigation of durvalumab in early-stage cancers. Herein, we describe the extensive clinical development program for durvalumab across multiple tumor types in curative-intent settings, outlining the scientific rationale(s) for its use and highlighting the innovative research (e.g., personalized cancer monitoring) advanced by these trials.

Regulation of the chemokine receptor CXCR4 by hypoxia.

Cell adaptation to hypoxia (Hyp) requires activation of transcriptional programs that coordinate expression of genes involved in oxygen delivery (via angiogenesis) and metabolic adaptation (via glycolysis). Here, we describe that oxygen availability is a determinant parameter in the setting of chemotactic responsiveness to stromal-derived factor 1 (CXCL12). Low oxygen concentration induces high expression of the CXCL12 receptor, CXC receptor 4 (CXCR4), in different cell types (monocytes, monocyte-derived macrophages, tumor-associated macrophages, endothelial cells, and cancer cells), which is paralleled by increased chemotactic responsiveness to its specific ligand. CXCR4 induction by Hyp is dependent on both activation of the Hyp-inducible factor 1 alpha and transcript stabilization. In a relay multistep navigation process, the Hyp-Hyp-inducible factor 1 alpha-CXCR4 pathway may regulate trafficking in and out of hypoxic tissue microenvironments.

Endothelial monocyte activating polypeptide-II modulates endothelial cell responses by degrading hypoxia-inducible factor-1alpha through interaction with PSMA7, a component of the proteasome.

The majority of human tumors are angiogenesis dependent. Understanding the specific mechanisms that contribute to angiogenesis may offer the best approach to develop therapies to inhibit angiogenesis in cancer. Endothelial monocyte activating polypeptide-II (EMAP-II) is an anti-angiogenic cytokine with potent effects on endothelial cells (ECs). It inhibits EC proliferation and cord formation, and it suppresses primary and metastatic tumor growth in-vivo. However, very little is known about the molecular mechanisms behind the anti-angiogenic activity of EMAP-II. In the present study, we explored the molecular mechanism behind the anti-angiogenic activity exerted by this protein on ECs. Our results demonstrate that EMAP-II binds to the cell surface alpha5beta1 integrin receptor. The cell surface binding of EMAP-II results in its internalization into the cytoplasmic compartment where it interacts with its cytoplasmic partner PSMA7, a component of the proteasome degradation pathway. This interaction increases hypoxia-inducible factor 1-alpha (HIF-1alpha) degradation under hypoxic conditions. The degradation results in the inhibition of HIF-1alpha mediated transcriptional activity as well as HIF-1alpha mediated angiogenic sprouting of ECs. HIF-1alpha plays a critical role in angiogenesis by activating a variety of angiogenic growth factors. Our results suggest that one of the major anti-angiogenic functions of EMAP-II is exerted through its inhibition of the HIF-1alpha activities.

Role of the hypoxic tumor microenvironment in the resistance to anti-angiogenic therapies.

Angiogenesis, a key process for the growth of human cancers, has recently been exploited for the development of a novel class of cancer therapeutics that was thought to have wide applications and not to induce resistance in the clinical setting. Indeed, anti-angiogenic therapy has become an important option for the management of several human malignancies. However, a significant number of patients either do not respond to anti-angiogenic agents or fairly rapidly develop resistance. In addition, the benefit of anti-angiogenic therapy is relatively short-lived and the majority of patients eventually relapses and progresses. Several mechanisms of resistance to anti-angiogenic therapy have been recently proposed. The current review focuses on the role of intra-tumor hypoxia as a mechanism of resistance to anti-angiogenic agents and speculates on therapeutic approaches that might circumvent resistance and thereby improve clinical outcome.

Development of HIF-1 inhibitors for cancer therapy.

Intratumour hypoxia has long been considered a driving force of tumour progression and a negative prognostic factor in human cancers. The discovery of hypoxia inducible factors (HIFs), which mediate transcriptional responses to changes in oxygen levels, has renewed enthusiasm for the discovery and development of targeted therapies exploiting the hypoxic tumour microenvironment. In spite of an ever increasing number of putative small molecule inhibitors of HIF, only few progress through pre-clinical and early clinical development. In this review, we will focus primarily on: (1) HIF inhibitors that have been more recently described and (2) small molecules targeting HIF that are being tested in early clinical trials or that are already approved for use in patients. A rigorous 'validation' of HIF targeted therapies in relevant pre-clinical models and eventually in pharmacodynamic-based early clinical trials is essential for 'credentialing' HIF-1 as a legitimate target that can be pharmacologically modulated in cancer patients.

Cytotoxic and HIF-1alpha inhibitory compounds from Crossosoma bigelovii.

Cytotoxicity-guided fractionation of an organic solvent extract of the plant Crossosoma bigelovii led to the discovery of a new strophanthidin glycoside (1) and two new 2-methylchromone glycosides (2 and 3). Also isolated were the known chromones eugenin and noreugenin, the indole alkaloid ajmalicine, the dibenzylbutane lignan secoisolariciresinol, the dibenzylbutyrolactone lignan matairesinol, and the furanone 5-tetradec-5-enyldihydrofuran-2-one. Further investigation into the biological properties of strophanthidin glycosides revealed a connection between inhibition of HIF-1 activation and the glycosylation of the genin. This work is the first published study of the bioactive phytochemicals of the family Crossosomataceae.

Safety and Efficacy of Durvalumab With or Without Tremelimumab in Patients With PD-L1-Low/Negative Recurrent or Metastatic HNSCC: The Phase 2 CONDOR Randomized Clinical Trial.

Importance: Dual blockade of programmed death ligand 1 (PD-L1) and cytotoxic T-lymphocyte associated protein 4 (CTLA-4) may overcome immune checkpoint inhibition. It is unknown whether dual blockade can potentiate antitumor activity without compromising safety in patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) and low or no PD-L1 tumor cell expression. Objective: To assess safety and objective response rate of durvalumab combined with tremelimumab. Design, Setting, and Participants: The CONDOR study was a phase 2, randomized, open-label study of Durvalumab, Tremelimumab, and Durvalumab in Combination With Tremelimumab in Patients With R/M HNSCC. Eligibility criteria included PD-L1-low/negative disease that had progressed after 1 platinum-containing regimen in the R/M setting. Patients were randomized (N = 267) from April 15, 2015, to March 16, 2016, at 127 sites in North America, Europe, and Asia Pacific. Interventions: Durvalumab (20 mg/kg every 4 weeks) + tremelimumab (1 mg/kg every 4 weeks) for 4 cycles, followed by durvalumab (10 mg/kg every 2 weeks), or durvalumab (10 mg/kg every 2 weeks) monotherapy, or tremelimumab (10 mg/kg every 4 weeks for 7 doses then every 12 weeks for 2 doses) monotherapy. Main Outcomes and Measures: Safety and tolerability and efficacy measured by objective response rate. Results: Among the 267 patients (220 men [82.4%]), median age (range) of patients was 61.0 (23-82) years. Grade 3/4 treatment-related adverse events occurred in 21 patients (15.8%) treated with durvalumab + tremelimumab, 8 (12.3%) treated with durvalumab, and 11 (16.9%) treated with tremelimumab. Grade 3/4 immune-mediated adverse events occurred in 8 patients (6.0%) in the combination arm only. Objective response rate (95% CI) was 7.8% (3.78%-13.79%) in the combination arm (n = 129), 9.2% (3.46%-19.02%) for durvalumab monotherapy (n = 65), and 1.6% (0.04%-8.53%) for tremelimumab monotherapy (n = 63); median overall survival (95% CI) for all patients treated was 7.6 (4.9-10.6), 6.0 (4.0-11.3), and 5.5 (3.9-7.0) months, respectively. Conclusions and Relevance: In patients with R/M HNSCC and low or no PD-L1 tumor cell expression, all 3 regimens exhibited a manageable toxicity profile. Durvalumab and durvalumab + tremelimumab resulted in clinical benefit, with minimal observed difference between the two. A phase 3 study is under way. Trial Registration: clinicaltrials.gov Identifier: NCT02319044.

Durvalumab for recurrent or metastatic head and neck squamous cell carcinoma: Results from a single-arm, phase II study in patients with ≥25% tumour cell PD-L1 expression who have progressed on platinum-based chemotherapy.

BACKGROUND: Patients with recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC) progressing on platinum-based chemotherapy have poor prognoses and limited therapeutic options. Programmed cell death-1 (PD-1) and its ligand 1 (PD-L1) are frequently upregulated in HNSCC. The international, multi-institutional, single-arm, phase II HAWK study (NCT02207530) evaluated durvalumab monotherapy, an anti-PD-L1 monoclonal antibody, in PD-L1-high patients with platinum-refractory R/M HNSCC. PATIENTS AND METHODS: Immunotherapy-naïve patients with confirmed PD-L1-high tumour cell expression (defined as patients with ≥25% of tumour cells expressing PD-L1 [TC ≥ 25%] using the VENTANA PD-L1 [SP263] Assay) received durvalumab 10 mg/kg intravenously every 2 weeks for up to 12 months. The primary end-point was objective response rate; secondary end-points included progression-free survival (PFS) and overall survival (OS). RESULTS: Among evaluable patients (n = 111), objective response rate was 16.2% (95% confidence interval [CI], 9.9-24.4); 29.4% (95% CI, 15.1-47.5) for human papillomavirus (HPV)-positive patients and 10.9% (95% CI, 4.5-21.3) for HPV-negative patients. Median PFS and OS for treated patients (n = 112) was 2.1 months (95% CI, 1.9-3.7) and 7.1 months (95% CI, 4.9-9.9); PFS and OS at 12 months were 14.6% (95% CI, 8.5-22.1) and 33.6% (95% CI, 24.8-42.7). Treatment-related adverse events were 57.1% (any grade) and 8.0% (grade ≥3); none led to death. At data cut-off, 24.1% of patients remained on treatment or in follow-up. CONCLUSION: Durvalumab demonstrated antitumour activity with acceptable safety in PD-L1-high patients with R/M HNSCC, supporting its ongoing evaluation in phase III trials in first- and second-line settings. In an ad hoc analysis, HPV-positive patients had a numerically higher response rate and survival than HPV-negative patients.

Cell type-specific, topoisomerase II-dependent inhibition of hypoxia-inducible factor-1alpha protein accumulation by NSC 644221.

PURPOSE: The discovery and development of small-molecule inhibitors of hypoxia-inducible factor-1 (HIF-1) is an attractive, yet challenging, strategy for the development of new cancer therapeutic agents. Here, we report on a novel tricyclic carboxamide inhibitor of HIF-1alpha, NSC 644221. EXPERIMENTAL DESIGN: We investigated the mechanism by which the novel compound NSC 644221 inhibited HIF-1alpha. RESULTS: NSC 644221 inhibited HIF-1-dependent, but not constitutive, luciferase expression in U251-HRE and U251-pGL3 cells, respectively, as well as hypoxic induction of vascular endothelial growth factor mRNA expression in U251 cells. HIF-1alpha, but not HIF-1beta, protein expression was inhibited by NSC 644221 in a time- and dose-dependent fashion. Interestingly, NSC 644221 was unable to inhibit HIF-1alpha protein accumulation in the presence of the proteasome inhibitors MG132 or PS341, yet it did not directly affect the degradation of HIF-1alpha as shown by experiments done in the presence of cyclohexamide or pulse-chase labeling using [35S]methionine. In contrast, NSC 644221 decreased the rate of HIF-1alpha translation relative to untreated controls. Silencing of topoisomerase (topo) IIalpha, but not topo I, by specific small interfering RNA completely blocked the ability of NSC 644221 to inhibit HIF-1alpha. The data presented show that topo II is required for the inhibition of HIF-1alpha by NSC 644221. Furthermore, although NSC 644221 induced p21 expression, gammaH2A.X, and G2-M arrest in the majority of cell lines tested, it only inhibited HIF-1alpha in a distinct subset of cells, raising the possibility of pathway-specific "resistance" to HIF-1 inhibition in cancer cells. CONCLUSIONS: NSC 644221 is a novel HIF-1 inhibitor with potential for use as both an analytic tool and a therapeutic agent. Our data provide a strong rationale for pursuing the preclinical development of NSC 644221 as a HIF-1 inhibitor.

Phase I trial of MS-275, a histone deacetylase inhibitor, administered weekly in refractory solid tumors and lymphoid malignancies.

PURPOSE: MS-275 is a histone deacetylase inhibitor that has shown potent and unique anticancer activity in preclinical models. The aims of this phase I trial were to determine the dose-limiting toxicities and maximum tolerated dose of oral MS-275 in humans administered with food on a once weekly schedule and to study the pharmacokinetics of oral MS-275. EXPERIMENTAL DESIGN: Patients with refractory solid tumors and lymphoid malignancies were treated with oral MS-275 on a once weekly schedule for 4 weeks of a 6-week cycle. Samples for pharmacokinetic and pharmacodynamic analyses were collected during cycle 1. Protein acetylation in subpopulations of peripheral blood mononuclear cells was measured using a multivariable flow cytometry assay. RESULTS: A total of 22 patients were enrolled, and 19 were considered evaluable for toxicity. The maximum tolerated dose was 6 mg/m(2). No National Cancer Institute Common Toxicity Criteria grade 4 toxicities were observed. Dose-limiting grade 3 toxicities were reversible and consisted of hypophosphatemia, hyponatremia, and hypoalbuminemia. Non-dose-limiting grade 3 myelosuppression was also observed. The mean terminal half-life of MS-275 was 33.9 +/- 26.2 and the T(max) ranged from 0.5 to 24 h. Although there was considerable interpatient variability in pharmacokinetics, the area under the plasma concentration versus time curve increased linearly with dose. CONCLUSIONS: MS-275 is well tolerated at a dose of 6 mg/m(2) administered weekly with food for 4 weeks every 6 weeks. Drug exposure increases linearly with dose, and protein acetylation increased in all the subpopulations of peripheral blood mononuclear cells following MS-275 administration.

Meeting report: exploiting the tumor microenvironment for therapeutics.

Recent progress in understanding the role of the tumor microenvironment in cancer progression was the subject of the 2nd International Tumor Metabolism Summit entitled "Exploiting the Tumor Microenvironment for Therapeutics," a meeting held at Palazzo Ducale in Genoa, Italy, October 7 to 8, 2005. One of the major conceptual advances in oncology over the last decade has been the appreciation that all major aspects of cancer biology are influenced by the tumor microenvironment. Two important means by which cancer cells adapt to their microenvironment are by reprogramming cellular glucose/energy metabolism to use pathways that generate ATP in the absence of O(2) and by stimulating angiogenesis to increase O(2) delivery. These responses are principally mediated at the transcriptional level by hypoxia-inducible factor-1. This meeting emphasized the complexity of the tumor microenvironment and opportunities for therapeutic intervention by targeting transcriptional and metabolic pathways that are activated during cancer progression. A better understanding of the crosstalk between signaling pathways and metabolic alterations that contribute to the cancer phenotype may provide insights leading to the development of novel therapeutic strategies.

Inhibiting hypoxia-inducible factor 1 for cancer therapy.

Hypoxia has long been recognized as a common feature of solid tumors and a negative prognostic factor for response to treatment and survival of cancer patients. The discovery of hypoxia-inducible factor 1 (HIF-1), a molecular determinant of the response of mammalian cells to hypoxia, has led to the identification of a "molecular target" of hypoxia suitable for the development of cancer therapeutics. Early controversy about whether or not HIF-1 is a good target for therapy has not discouraged academic groups and pharmaceutical companies from actively engaging in the discovery of small-molecule inhibitors of HIF. However, what is the best strategy to inhibit HIF and how HIF inhibitors should be developed for treatment of human cancers is still poorly defined. In this review, aspects related to the identification and early development of novel HIF inhibitors are discussed. Identification and validation of pharmacodynamic end points relevant to the HIF-1 pathway is essential for a rational development of HIF inhibitors. Integration of these biomarkers in early clinical trials may provide valuable information to determine the contribution of HIF inhibitors to response to therapy. Finally, HIF inhibitors should be incorporated in combination strategies to effectively target multiple cellular components of the tumor microenvironment and redundant signaling pathways frequently deregulated in human cancer.