Ajay V. Maker

Autoimmunity Correlates With Tumor Regression in Patients With Metastatic Melanoma Treated With Anti–Cytotoxic T-Lymphocyte Antigen-4

PURPOSE Previously, we reported our experience treating 14 patients with metastatic melanoma using a fully human antibody to cytotoxic T-lymphocyte antigen-4 (anti-CTLA-4) in conjunction with peptide vaccination. We have now treated 56 patients to evaluate two different dose schedules of anti-CTLA-4 and to explore the relationship between autoimmunity and tumor regression. PATIENTS AND METHODS A total of 56 patients with progressive stage IV melanoma were enrolled onto the study. All had Karnofsky performance status > or = 60% with no prior history of autoimmunity. Twenty-nine patients received 3 mg/kg anti-CTLA-4 every 3 weeks, whereas 27 received 3 mg/kg as their initial dose with subsequent doses reduced to 1 mg/kg every 3 weeks. In both cohorts patients received concomitant vaccination with two modified HLA-A*0201-restricted peptides from the gp100 melanoma-associated antigen, gp100:209-217(210M) and gp100:280-288(288V). RESULTS Two patients achieved a complete response (ongoing at 30 and 31 months, respectively) and five patients achieved a partial response (durations of 4, 6, 25+, 26+, and 34+ months, respectively), for an overall objective response rate of 13%. Tumor regression was seen in lung, liver, brain, lymph nodes, and subcutaneous sites. Of 14 patients with grade 3/4 autoimmune toxicity, five (36%) experienced a clinical response compared with only two responses in the 42 patients (5%) with no autoimmune toxicity (P = .008). There were no significant differences in response rate or toxicity between the two dose schedules. CONCLUSION Administration of anti-CTLA-4 monoclonal antibody plus peptide vaccination can cause durable objective responses, which correlate with the induction of autoimmunity, in patients with metastatic melanoma.

Tumor Regression and Autoimmunity in Patients Treated With Cytotoxic T Lymphocyte–Associated Antigen 4 Blockade and Interleukin 2: A Phase I/II Study

BackgroundCytotoxic T lymphocyte–associated antigen (CTLA)-4 can inhibit T-cell responses and is involved in tolerance against self antigens. We previously reported autoimmune manifestations and objective cancer regressions in patients with metastatic melanoma treated with CTLA-4 blockade. The possibility of activating tumor-reactive T cells while removing inhibitory activity with CTLA-4 blockade has stimulated interest in using anti–CTLA-4 antibodies in combination with other cancer immunotherapies to improve clinical outcomes. In this study, we assessed the antitumor activity and autoimmune toxicity of CTLA-4 blockade in combination with an immune-activating stimulus, interleukin (IL)-2, in patients with metastatic melanoma.MethodsThirty-six patients received anti–CTLA-4 antibody every 3 weeks. Three patients per cohort received doses of .1, .3, 1.0, and 2.0 mg/kg. Twenty-four patients received 3.0 mg/kg. All patients received IL-2 therapy (720,000 IU/kg every 8 hours to a maximum of 15 doses).ResultsEight patients (22%) experienced objective tumor responses (three complete and five partial), including metastases in the lungs, lymph nodes, mediastinum, and subcutaneous tissues. Six of the eight patients have ongoing objective responses at 11 to 19 months. Five patients (14%) developed grade III/IV autoimmune toxicities secondary to anti–CTLA-4 administration, including four patients with enterocolitis and one with arthritis and uveitis.ConclusionsThere is not evidence to support a synergistic effect of CTLA-4 blockade plus IL-2 administration, because the 22% objective response rate is that expected from the sum of these two agents administered alone. Durable cancer regressions were seen in patients treated with this combination.

Analysis of the Cellular Mechanism of Antitumor Responses and Autoimmunity in Patients Treated with CTLA-4 Blockade

We have demonstrated previously that the administration of CTLA-4 blockade has mediated objective cancer regression and autoimmunity in patients with metastatic melanoma. To explore the mechanism of these in vivo effects, we have studied the changes in lymphocyte phenotype and function in patients receiving anti-CTLA-4 Ab (MDX-010). Patients with stage IV melanoma or renal cell cancer were treated every 3 wk with an anti-CTLA-4 Ab with or without peptide immunization. Pheresis samples were analyzed using flow cytometry to determine lymphocyte cell surface markers. Gene expression analyses and proliferation assays were conducted on purified T cell subsets. Anti-CTLA-4 Ab did not inhibit the suppressive activity of CD4+CD25+ cells in vitro or in vivo. In addition, there was no decrease in the expression of CD4+CD25+ cells in whole PBMC, nor a decrease in Foxp3 gene expression in the CD4+ or CD4+CD25+ purified cell populations posttreatment. The percentage of CD4+, CD8+, CD4+CD25+, and CD4+CD25− T cells in PBMC expressing the activation marker HLA-DR increased following anti-CTLA-4 Ab administration. Therefore, our results suggest that the antitumor effects of CTLA-4 blockade are due to increased T cell activation rather than inhibition or depletion of T regulatory cells.

Inability of a Fusion Protein of IL-2 and Diphtheria Toxin (Denileukin Diftitox, DAB389IL-2, ONTAK) to Eliminate Regulatory T Lymphocytes in Patients With Melanoma

Elimination of regulatory T lymphocytes may provide a way to break self-tolerance and unleash the anti-tumor properties of circulating lymphocytes. The use of fusion proteins, which link cytotoxic molecules to receptor targets, provides one approach to this problem. This study examined the ability of a fusion protein of interleukin-2 (IL-2) and diphtheria toxin (Denileukin Diftitox, DAB389IL-2, ONTAK) to eliminate regulatory T lymphocytes based on their expression of high-affinity IL-2 receptors. Thirteen patients (12 with metastatic melanoma, 1 with metastatic renal cell carcinoma) were treated at one of the two Food and Drug Administration-approved doses of Denileukin Diftitox (seven patients at 9 μg/kg, six patients at 18 μg/kg). None of the patients experienced an objective clinical response. Foxp3 expression did not decrease significantly overall, although it did decrease minimally among patients receiving 18 μg/kg (−2.01 ± 0.618 copies of Foxp3/103 copies of β-actin; P = 0.031). Denileukin Diftitox did not decrease the suppressive ability of CD4+CD25+ cells as quantified by an in vitro co-culture suppression assay. Furthermore, the increased numbers of lymphocytes in patients resulting from treatment with IL-2 were not susceptible to Denileukin Diftitox. Administration of Denileukin Diftitox does not appear to eliminate regulatory T lymphocytes or cause regression of metastatic melanoma.

Intrapatient dose escalation of anti-CTLA-4 antibody in patients with metastatic melanoma

We previously reported our experience in treating 56 patients with metastatic melanoma using a human anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) antibody. Durable tumor regressions were seen that correlated with the induction of autoimmune toxicities. In this study, we treated 46 additional patients using an intrapatient dose escalation schema to test whether higher doses of anti–CTLA-4 antibody would induce increased autoimmunity and concomitant tumor regression. Twenty-three patients started anti–CTLA-4 antibody administration at 3 mg/kg and 23 patients started treatment at 5 mg/kg, receiving doses every 3 weeks. Patients were dose-escalated every other dose to a maximum of 9 mg/kg or until objective clinical responses or grade III/IV autoimmune toxicity were seen. Escalating doses of antibody resulted in proportionally higher plasma concentrations. Sixteen patients (35%) experienced a grade III/IV autoimmune toxicity. Five patients (11%) achieved an objective clinical response. Two of the responses are ongoing at 13 and 16 months, respectively. Flow cytometric analysis of peripheral blood revealed significant increases in both T-cell surface markers of activation and memory phenotype. Thus, higher serum levels and prolonged administration of anti–CTLA-4 antibody resulted in a trend toward a greater incidence of grade III/IV autoimmune toxicity than previously reported, but did not seem to increase objective response rates.

Selective elimination of human regulatory T lymphocytes in vitro with the recombinant immunotoxin LMB-2.

CD4+CD25+ T-regulatory cells (Treg) can inhibit the proliferation and cytokine secretion of CD4+CD25− helper T cells in mice and humans. In murine tumor models, the presence of these Treg cells can inhibit the antitumor effectiveness of T-cell transfer and active immunization approaches. We have thus initiated efforts to eliminate Treg cells selectively from human peripheral blood mononuclear cells (PBMCs) to potentially bolster antitumor responses. LMB-2 is a recombinant immunotoxin that is a fusion of a single-chain Fv fragment of the anti-Tac anti-CD25 monoclonal antibody to a truncated form of the bacterial Pseudomonas exotoxin A. In vitro incubation of human PBMCs with LMB-2 reduced the levels of CD4+CD25+ and Foxp3-expressing cells without impairing the function of the remaining lymphocytes. The short in vivo half-life of LMB-2 makes it an attractive candidate for reducing human Treg cells in vivo before the administration of cancer vaccine or cell transfer immunotherapy approaches.

Cyst Fluid Interleukin-1β (IL1β) Levels Predict the Risk of Carcinoma in Intraductal Papillary Mucinous Neoplasms of the Pancreas

Purpose: Biomarkers for high-grade dysplasia in patients with radiographically identified intraductal papillary mucinous neoplasms (IPMN) have not been described. We hypothesized that dysplasia in IPMN invokes an immunogenic/proinflammatory microenvironment that can be identified by cyst fluid cytokine levels. Experimental Design: Pancreatic cyst fluid aspirates were collected at resection (2005–2009). Samples were grouped into low-risk [low-grade (n = 6) or moderate dysplasia (n = 15)] and high-risk groups [high-grade dysplasia (n = 13) or carcinoma (n = 6)]. Cytokine expression was determined using a multiplex sandwich immunoassay. Differences in cytokine expression were evaluated using the 2-sample t test. Sample classification was performed using a logistic regression adjusting for sample covariates. Results: IL5 and IL8 concentrations were higher in the cyst fluid from patients in the high-risk group than the low-risk group. Interleukin (IL)-1β concentrations were also higher in the cyst fluid from patients with high-grade dysplasia or cancer (n = 19) than those with low- or moderate-grade dysplasia (n = 21, 539 ± 255 pg/mL vs. 0.2 ± 0.1 pg/mL; P < 0.0001). IL1β remained a significant predictor of high-risk cysts after multivariate analysis. There was no significant difference in levels of IL2, IL4, IL10, IL12, IL13, TNF-α, or IFN-γ between the groups. That IL1β levels identified cysts at a high risk of malignancy was confirmed in an independent validation set. Conclusions: Cyst fluid levels of IL1β can differentiate low- from high-risk IPMN. This study introduces IL1β as a potential biomarker for validation in larger clinical studies. Clin Cancer Res; 17(6); 1502–8. ©2011 AACR.

Insulin receptor (IR) and glucose transporter 2 (GLUT2) proteins form a complex on the rat hepatocyte membrane.

The hepatic glucose transporter, GLUT2, facilitates bidirectional glucose transport across the hepatocyte plasma membrane under insulin regulation. We studied the interactions of IR and GLUT2 proteins to determine whether they are physically coupled in a receptor-transporter complex. By comparing endosome and plasma membrane IR and GLUT2 ratios before and after feeding, it was determined that IR and GLUT2 are internalized in a fixed ratio. When solubilized hepatocytes were immunoprecipitated with antibodies against either IR or GLUT2, both proteins co-precipitated. The association of IR and GLUT2 was further assessed by confocal microscopy. Sections of fed liver were incubated with fluorescein-tagged anti-GLUT2 or Texas Red-tagged anti-IR. Colocalization was observed both at the plasma membrane and in the cytosol. Fluorescence-resonance energy transfer studies further confirmed this association. We conclude that IR and GLUT2 form a receptor-transporter complex in hepatocytes, which forms a mechanism of insulin-mediated hepatic glucose regulation.

Cyst Fluid Biomarkers for Intraductal Papillary Mucinous Neoplasms of the Pancreas: A Critical Review from the International Expert Meeting on Pancreatic Branch-Duct-Intraductal Papillary Mucinous Neoplasms

The recognition of pancreatic cysts and intraductal papillary mucinous neoplasms of the pancreas (IPMN) has increased largely secondary to greater utilization of high-quality cross-sectional abdominal imaging.1, 2 Although the general characteristics of IPMNs, radiographic diagnosis, cyst fluid composition, and their delineation from other pancreatic tumors have been well established, several issues regarding their growth and progression into malignancy remain poorly described. The degree of neoplastic transformation within IPMN is highly variable, from those with an entirely innocuous cell population typically resembling gastric epithelium and lacking any cytologic atypia, to those that have progressively increasing degrees of cytoarchitectural atypia. Though some patients with highly dysplastic and invasive IPMN may present with clinical symptoms or characteristic radiographic findings, including jaundice, an associated pancreatic mass, or main pancreatic duct dilation; increasingly IPMN are incidentally discovered. Once IPMN are radiographically diagnosed, there is currently no reliable way to determine the level of epithelial dysplasia or to predict the time frame of progression to high-grade dysplasia or cancer.3–6 A biologic marker of IPMNs is urgently needed – one that can be easily obtained and tested without significant morbidity for the patient. An evidence-based expert meeting on pancreatic branch-duct IPMNs (BD-IMPN) was held in Verona, Italy and the authors reviewed the current role of existing technologies and molecular markers for predicting the biological behavior of IPMNs. The status of endoscopic ultrasound (EUS) and EUS-guided fine needle aspiration (FNA) cytology, cyst fluid biochemistry, mucins, cytokines, DNA, and microRNA profiles were critically reviewed by the group in order to identify the most promising clinically relevant biomarkers, and to target analyses for further development. Endoscopic ultrasound Endoscopic ultrasound (EUS) is a highly sensitive imaging modality for the evaluation of pancreatic cystic lesions that was developed as a diagnostic modality, but rapidly gained a role in IPMN for morphologic assessment and for its interventional capabilities, namely aspiration of cyst fluid and fine-needle aspiration (FNA). Diagnosis of IPMN based solely on EUS findings requires attention to cyst size, characteristics of the cyst wall, internal characteristics of the cyst, communication with the MPD, and the existence of any background lesions. Using EUS morphologic parameters, the sensitivity, specificity and accuracy to differentiate between benign and malignant, or potentially malignant, cystic lesions has been reported to be between 56%–91%, 45%–60% and 51%–72%, respectively7, 8 Although evaluation and the differential diagnosis of cystic lesions based solely on EUS morphology is feasible; inter-observer variability, operator dependency, and moderate diagnostic performance limit its accuracy without the addition of cyst fluid aspiration and FNA cytology, especially for determination of high-risk IPMN without overt malignant features.

Essential roles of FoxM1 in Ras-induced liver cancer progression and in cancer cells with stem cell features

BACKGROUND & AIMS Overexpression of FoxM1 correlates with poor prognosis in hepatocellular carcinoma (HCC). Moreover, the Ras-signaling pathway is found to be ubiquitously activated in HCC through epigenetic silencing of the Ras-regulators. We investigated the roles of FoxM1 in Ras-driven HCC, and on HCC cells with stem-like features. METHODS We employed a transgenic mouse model that expresses the oncogenic Ras in the liver. That strain was crossed with a strain that harbor floxed alleles of FoxM1 and the MxCre gene that allows conditional deletion of FoxM1. FoxM1 alleles were deleted after development of HCC, and the effects on the tumors were analyzed. Also, FoxM1 siRNA was used in human HCC cell lines to determine its role in the survival of the HCC cells with stem cell features. RESULTS Ras-driven tumors overexpress FoxM1. Deletion of FoxM1 inhibits HCC progression. There was increased accumulation of reactive oxygen species (ROS) in the FoxM1 deleted HCC cells. Moreover, FoxM1 deletion caused a disproportionate loss of the CD44+ and EpCAM+ HCC cells in the tumors. We show that FoxM1 directly activates expression of CD44 in human HCC cells. Moreover, the human HCC cells with stem cell features are addicted to FoxM1 for ROS-regulation and survival. CONCLUSION Our results provide genetic evidence for an essential role of FoxM1 in the progression of Ras-driven HCC. In addition, FoxM1 is required for the expression of CD44 in HCC cells. Moreover, FoxM1 plays a critical role in the survival of the HCC cells with stem cell features by regulating ROS.