Judith C. McCaffrey

HIF-1α regulates function and differentiation of myeloid-derived suppressor cells in the tumor microenvironment.

The hypoxic environment of tumors dictates the phenotype of local myeloid-derived suppressor cells (MDSCs) via HIF-1a expression; hypoxia converts splenic MDSCs from specific into nonspecific suppressors.

Mechanism Regulating Reactive Oxygen Species in Tumor-Induced Myeloid-Derived Suppressor Cells

Myeloid-derived suppressor cells (MDSC) are a major component of the immune suppressive network described in cancer and many other pathological conditions. Recent studies have demonstrated that one of the major mechanisms of MDSC-induced immune suppression is mediated by reactive oxygen species (ROS). However, the mechanism of this phenomenon remained unknown. In this study, we observed a substantial up-regulation of ROS by MDSC in all of seven different tumor models and in patients with head and neck cancer. The increased ROS production by MDSC is mediated by up-regulated activity of NADPH oxidase (NOX2). MDSC from tumor-bearing mice had significantly higher expression of NOX2 subunits, primarily p47phox and gp91phox, compared with immature myeloid cells from tumor-free mice. Expression of NOX2 subunits in MDSC was controlled by the STAT3 transcription factor. In the absence of NOX2 activity, MDSC lost the ability to suppress T cell responses and quickly differentiated into mature macrophages and dendritic cells. These findings expand our fundamental understanding of the biology of MDSC and may also open new opportunities for therapeutic regulation of these cells in cancer.

Lipid accumulation and dendritic cell dysfunction in cancer

Dendritic cells (DCs), a type of professional antigen-presenting cells, are responsible for initiation and maintenance of immune responses. Here we report that a substantial proportion of DCs in tumor-bearing mice and people with cancer have high amounts of triglycerides as compared with DCs from tumor-free mice and healthy individuals. In our studies, lipid accumulation in DCs was caused by increased uptake of extracellular lipids due to upregulation of scavenger receptor A. DCs with high lipid content were not able to effectively stimulate allogeneic T cells or present tumor-associated antigens. DCs with high and normal lipid levels did not differ in expression of major histocompatibility complex and co-stimulatory molecules. However, lipid-laden DCs had a reduced capacity to process antigens. Pharmacological normalization of lipid abundance in DCs with an inhibitor of acetyl-CoA carboxylase restored the functional activity of DCs and substantially enhanced the effects of cancer vaccines. These findings suggest that immune responses in cancer can be improved by manipulating the lipid levels in DCs.

Epigenetic silencing of retinoblastoma gene regulates pathologic differentiation of myeloid cells in cancer

Two major populations of myeloid-derived suppressor cells (MDSCs), monocytic MDSCs (M-MDSCs) and polymorphonuclear MDSCs (PMN-MDSCs) regulate immune responses in cancer and other pathologic conditions. Under physiologic conditions, Ly6ChiLy6G− inflammatory monocytes, which are the normal counterpart of M-MDSCs, differentiate into macrophages and dendritic cells. PMN-MDSCs are the predominant group of MDSCs that accumulates in cancer. Here we show that a large proportion of M-MDSCs in tumor-bearing mice acquired phenotypic, morphological and functional features of PMN-MDSCs. Acquisition of this phenotype, but not the functional attributes of PMN-MDSCs, was mediated by transcriptional silencing of the retinoblastoma gene through epigenetic modifications mediated by histone deacetylase 2 (HDAC-2). These data demonstrate a new regulatory mechanism of myeloid cells in cancer.

Prognostic Factors for Survival After Salvage Reirradiation of Head and Neck Cancer

PURPOSE Patients who develop recurrent or new primary head and neck cancer in a previously irradiated site have poor prognosis. Reirradiation is a treatment option, although it is associated with substantial toxicities. We investigated potential prognostic factors, including comorbidity and pre-existing organ dysfunction, for survival after reirradiation. METHODS Institutional electronic records of patients treated with reirradiation between January 1998 and 2008 were reviewed. Comorbidity was assessed by Charlson index and Adult Comorbidity Evaluation-27 (ACE-27) grading. Organ dysfunction was defined as feeding tube dependency, functioning tracheostomy, or soft tissue defect. RESULTS There were 103 patients, including 46 patients who underwent salvage surgery before reirradiation. Median progression-free and overall survivals were 12.1 months (95% CI, 9.7 to 16.6) and 19.3 months (95% CI, 13.9 to 29.9), respectively. Significant comorbidity was present in 36% of patients by Charlson index and 24% by ACE-27. Baseline organ dysfunction was present in 37% of patients. Median overall survivals were 5.5 months among those with both organ dysfunction and comorbidity per Charlson index, and 4.9 months per ACE-27, compared with 59.6 and 44.2 months, respectively, among the patients with neither organ dysfunction nor comorbidity (P < .001 and < .001). Other independent prognostic factors were interval from previous radiation, recurrent tumor stage, tumor bulk at reirradiation, and reirradiation dose. A nomogram to predict the probability of death within 24 months after reirradiation was developed (concordance index = 0.75). CONCLUSION Comorbidity and pre-existing organ dysfunction are among several important prognostic factors for patients undergoing reirradiation. For those with both comorbidity and organ dysfunction, reirradiation largely serves as a palliative therapy.

ER stress regulates myeloid-derived suppressor cell fate through TRAIL-R–mediated apoptosis

Myeloid-derived suppressor cells (MDSCs) dampen the immune response thorough inhibition of T cell activation and proliferation and often are expanded in pathological conditions. Here, we studied the fate of MDSCs in cancer. Unexpectedly, MDSCs had lower viability and a shorter half-life in tumor-bearing mice compared with neutrophils and monocytes. The reduction of MDSC viability was due to increased apoptosis, which was mediated by increased expression of TNF-related apoptosis-induced ligand receptors (TRAIL-Rs) in these cells. Targeting TRAIL-Rs in naive mice did not affect myeloid cell populations, but it dramatically reduced the presence of MDSCs and improved immune responses in tumor-bearing mice. Treatment of myeloid cells with proinflammatory cytokines did not affect TRAIL-R expression; however, induction of ER stress in myeloid cells recapitulated changes in TRAIL-R expression observed in tumor-bearing hosts. The ER stress response was detected in MDSCs isolated from cancer patients and tumor-bearing mice, but not in control neutrophils or monocytes, and blockade of ER stress abrogated tumor-associated changes in TRAIL-Rs. Together, these data indicate that MDSC pathophysiology is linked to ER stress, which shortens the lifespan of these cells in the periphery and promotes expansion in BM. Furthermore, TRAIL-Rs can be considered as potential targets for selectively inhibiting MDSCs.

Outcomes of Postoperative Concurrent Chemoradiotherapy for Locally Advanced Major Salivary Gland Carcinoma

OBJECTIVE To investigate the potential value of postoperative concurrent chemoradiation among patients with high-risk salivary gland carcinomas. DESIGN Case control study based on retrospective medical record review. SETTING A tertiary care comprehensive cancer center. PATIENTS A total of 24 patients, 12 with major salivary gland carcinoma who were treated with postoperative concurrent chemoradiotherapy from 1998 to 2007 (chemoradiation group), and a control group of 12 patients treated with postoperative radiation alone. MAIN OUTCOME MEASURES Overall survival, progression-free survival, toxic effects. RESULTS All but 1 patient had stage III or IV disease; close or positive surgical margins were identified in 20 patients (83%). The median radiation dose was 63 Gy. In the chemoradiation group, platinum-based regimens were used in all. Treatment was well tolerated, but toxic effects, predominantly hematologic, were increased in the chemoradiation group. To date, 8 patients have died; the median overall survival was 53 months. The overall survival in the chemoradiation group was significantly better than in the radiation-alone group: 3-year survival rates were 83% and 44%, respectively (P = .05). CONCLUSIONS Locally advanced or high-grade salivary gland carcinomas follow an aggressive clinical course. Based on our limited experience, postoperative chemoradiation with a platinum-based regimen seems to be effective in selected patients and warrants further investigation.

CD45 Phosphatase Inhibits STAT3 Transcription Factor Activity in Myeloid Cells and Promotes Tumor-Associated Macrophage Differentiation.

Recruitment of monocytic myeloid-derived suppressor cells (MDSCs) and differentiation of tumor-associated macrophages (TAMs) are the major factors contributing to tumor progression and metastasis. We demonstrated that differentiation of TAMs in tumor site from monocytic precursors was controlled by downregulation of the activity of the transcription factor STAT3. Decreased STAT3 activity was caused by hypoxia and affected all myeloid cells but was not observed in tumor cells. Upregulation of CD45 tyrosine phosphatase activity in MDSCs exposed to hypoxia in tumor site was responsible for downregulation of STAT3. This effect was mediated by the disruption of CD45 protein dimerization regulated by sialic acid. Thus, STAT3 has a unique function in the tumor environment in controlling the differentiation of MDSC into TAM, and its regulatory pathway could be a potential target for therapy.

A Phase II Trial of the Multitargeted Tyrosine Kinase Inhibitor Lenvatinib (E7080) in Advanced Medullary Thyroid Cancer

Purpose: Positive results of phase I studies evaluating lenvatinib in solid tumors, including thyroid cancer, prompted a phase II trial in advanced medullary thyroid carcinoma (MTC). Experimental Design: Fifty-nine patients with unresectable progressive MTC per Response Evaluation Criteria In Solid Tumors (RECIST) v1.0 within the prior 12 months received lenvatinib (24-mg daily, 28-day cycles) until disease progression, unmanageable toxicity, withdrawal, or death. Prior anti-VEGFR therapy was permitted. The primary endpoint was objective response rate (ORR) by RECIST v1.0 and independent imaging review. Results: Lenvatinib ORR was 36% [95% confidence interval (CI), 24%–49%]; all partial responses. ORR was comparable between patients with (35%) or without (36%) prior anti-VEGFR therapy. Disease control rate (DCR) was 80% (95% CI, 67%–89%); 44% had stable disease. Among responders, median time to response (TTR) was 3.5 months (95% CI, 1.9–3.7). Median progression-free survival (PFS) was 9.0 months (95% CI, 7.0–not evaluable). Common toxicity criteria grade 3/4 treatment-emergent adverse events included diarrhea (14%), hypertension (7%), decreased appetite (7%), fatigue, dysphagia, and increased alanine aminotransferase levels (5% each). Ret proto-oncogene status did not correlate with outcomes. Low baseline levels of angiopoietin-2, hepatocyte growth factor, and IL8 were associated with tumor reduction and prolonged PFS. High baseline levels of VEGF, soluble VEGFR3, and platelet-derived growth factor BB, and low baseline levels of soluble Tie-2, were associated with tumor reduction. Conclusions: Lenvatinib had a high ORR, high DCR, and a short TTR in patients with documented progressive MTC. Toxicities were managed with dose modifications and medications. Clin Cancer Res; 22(1); 44–53. ©2015 AACR.

Aerodigestive Tract Invasion by Well-Differentiated Thyroid Carcinoma: Diagnosis, Management, Prognosis, and Biology

Objectives/Hypothesis: 1) To describe the clinical entity invasive well‐differentiated thyroid carcinoma (IWDTC), 2) to determine prognostic factors for survival in patients with IWDTC, 3) to describe and compare types of surgical resection to determine treatment efficacy, 4) to offer a staging system and surgical algorithm for management of patients with IWDTC, 5) to examine alterations in expression of E‐cadherin and β‐catenin adhesion molecules in three groups of thyroid tissue and propose a cellular mechanism for invasion of the aerodigestive tract.