Tofacitinib to prevent anti-drug antibody formation against LMB-100 immunotoxin in patients with advanced mesothelin-expressing cancers.

Background: LMB-100 is a mesothelin (MSLN)-targeting recombinant immunotoxin (iTox) carrying a Pseudomonas exotoxin A payload that has shown promise against solid tumors, however, efficacy is limited by the development of neutralizing anti-drug antibodies (ADAs). Tofacitinib is an oral Janus Kinase (JAK) inhibitor that prevented ADA formation against iTox in preclinical studies. Methods: A phase 1 trial testing LMB-100 and tofacitinib in patients with MSLN-expressing cancers (pancreatic adenocarcinoma, n=13; cholangiocarcinoma, n=1; appendiceal carcinoma, n=1; cystadenocarcinoma, n=1) was performed to assess safety and to determine if tofacitinib impacted ADA formation. Participants were treated for up to 3 cycles with LMB-100 as a 30-minute infusion on days 4, 6, and 8 at two dose levels (100 and 140 µg/kg) while oral tofacitinib was administered for the first 10 days of the cycle (10 mg BID). Peripheral blood was collected for analysis of ADA levels, serum cytokines and circulating immune subsets. Results: The study was closed early due to occurrence of drug-induced pericarditis in 2 patients. Pericarditis with the combination was not reproducible in a transgenic murine model containing human MSLN. Two of 4 patients receiving all 3 cycles of treatment maintained effective LMB-100 levels, an unusual occurrence. Sustained increases in systemic IL-10 and TNF-α were seen, a phenomenon not observed in prior LMB-100 studies. A decrease in activated T cell subsets and an increase in circulating immunosuppressive myeloid populations occurred. No radiologic decreases in tumor volume were observed. Discussion: Further testing of tofacitinib to prevent ADA formation is recommended in applicable non-malignant disease settings. Clinical trial registration: https://www.clinicaltrials.gov/study/NCT04034238.

Systemic immune changes accompany combination treatment with immunotoxin LMB-100 and nab-paclitaxel.

LMB-100 is a novel immune-conjugate (immunotoxin) that targets mesothelin. A phase 1/2 clinical trial was conducted (NCT02810418) with primary objectives assessing the safety and efficacy of LMB-100 ± nab-paclitaxel. Participant blood samples were analyzed for changes in serum cytokines and circulating immune cell subsets associated with response or toxicity. On Arm A, participants (n = 20) received standard 30-minute LMB-100 infusion with nab-paclitaxel. Although clinical efficacy was observed, the combination caused intolerable capillary leak syndrome (CLS), a major toxicity of unclear etiology that affects many immunotoxin drugs. Participants developing CLS experienced rapid elevations in IFNγ and IL-8 compared to those without significant CLS, along with midcycle increases in Ki-67- CD4 T cells that were CD38, HLA-DR, or TIM3 positive. Additionally, a strong increase in activated CD4 and CD8 T cells and a concurrent decrease in Tregs were seen in the single Arm A patient achieving a partial response. In Arm B, administration of single agent LMB-100 to participants (n = 20) as a long infusion given over 24-48 h was investigated based on pre-clinical data that this format could reduce CLS. An optimal dose and schedule of long infusion LMB-100 were identified, but no clinical efficacy was observed even in patients receiving LMB-100 in combination with nab-paclitaxel. Despite this, both Arm A and B participants experienced increases in specific subsets of proliferating CD4 and CD8 T cells following Cycle 1 treatment. In summary, LMB-100 treatment causes systemic immune activation. Inflammatory and immune changes that accompany drug associated CLS were characterized for the first time.

Low serum mesothelin in pancreatic cancer patients results from retention of shed mesothelin in the tumor microenvironment.

Mesothelin (MSLN) is overexpressed by many cancers, including pancreatic ductal adenocarcinoma (PDAC) and has consequently become a target for anti-cancer therapeutics. Mature, membrane bound MSLN is cleaved by proteases, releasing a shed form that transits to the circulation. Many patients with mesothelioma and ovarian cancer have abnormally high serum MSLN concentration. However, serum MSLN concentration in PDAC patients rarely exceeds levels of healthy controls. Here, serum MSLN concentration in advanced PDAC patients was examined pre- and post-treatment. Serum MSLN did not correlate with tumor MSLN expression, nor with changes in tumor burden as assessed by PDAC serum tumor marker CA19-9. Subsequently, tumor-bearing mouse models were used to investigate the fate of shed MSLN in PDAC versus a control cervical cancer model. Efficiency of MSLN secretion into the serum was cell-line dependent. Tumors from some PDAC lines had poor MSLN secretion efficiency although these lines had similar or higher MSLN shedding rate, total and surface MSLN expression. Measurements of compartment-specific MSLN concentration taken at equilibrium suggested that tumors with poor MSLN secretion efficiency trapped shed MSLN in the tumor microenvironment (TME), a finding confirmed by dynamic experiments using a doxycycline-inducible MSLN expression system. Tumors with the poorest MSLN secretion efficiency had higher collagen density and increased abundance of MSLN binding partner MUC16. The tumor with the worst secretion efficiency could rebind shed MSLN to the cancer cell surface. Altogether, these data suggest that PDAC can trap shed MSLN within the TME. This finding has potential significance for design of MSLN-targeted therapeutics.

Cabozantinib plus Nivolumab Phase I Expansion Study in Patients with Metastatic Urothelial Carcinoma Refractory to Immune Checkpoint Inhibitor Therapy.

PURPOSE: This study investigated the efficacy and tolerability of cabozantinib plus nivolumab (CaboNivo) in patients with metastatic urothelial carcinoma (mUC) that progressed on checkpoint inhibition (CPI). PATIENTS AND METHODS: A phase I expansion cohort of patients with mUC who received prior CPI was treated with cabozantinib 40 mg/day and nivolumab 3 mg/kg every 2 weeks until disease progression/unacceptable toxicity. The primary goal was objective response rate (ORR) per RECIST v.1.1. Secondary objectives included progression-free survival (PFS), duration of response (DoR), overall survival (OS), safety, and tolerability. RESULTS: Twenty-nine out of 30 patients enrolled were evaluable for efficacy. Median follow-up was 22.2 months. Most patients (86.7%) received prior chemotherapy and all patients received prior CPI (median seven cycles). ORR was 16.0%, with one complete response and three partial responses (PR). Among 4 responders, 2 were primary refractory, 1 had a PR, and 1 had stable disease on prior CPI. Median DoR was 33.5 months [95% confidence interval (CI), 3.7-33.5], median PFS was 3.6 months (95% CI, 2.1-5.5), and median OS was 10.4 months (95% CI, 5.8-19.5). CaboNivo decreased immunosuppressive subsets such as regulatory T cells (Tregs) and increased potential antitumor immune subsets such as nonclassical monocytes and effector T cells. A lower percentage of monocytic myeloid-derived suppressor cells (M-MDSC) and polymorphonuclear MDSCs, lower CTLA-4 and TIM-3 expression on Tregs, and higher effector CD4+ T cells at baseline were associated with better PFS and/or OS. CONCLUSIONS: CaboNivo was clinically active, well tolerated, and favorably modulated peripheral blood immune subsets in patients with mUC refractory to CPI.

Selenium and the 15kDa Selenoprotein Impact Colorectal Tumorigenesis by Modulating Intestinal Barrier Integrity.

Selenoproteins play important roles in many cellular functions and biochemical pathways in mammals. Our previous study showed that the deficiency of the 15 kDa selenoprotein (Selenof) significantly reduced the formation of aberrant crypt foci (ACF) in a mouse model of azoxymethane (AOM)-induced colon carcinogenesis. The objective of this study was to examine the effects of Selenof on inflammatory tumorigenesis, and whether dietary selenium modified these effects. For 20 weeks post-weaning, Selenof-knockout (KO) mice and littermate controls were fed diets that were either deficient, adequate or high in sodium selenite. Colon tumors were induced with AOM and dextran sulfate sodium. Surprisingly, KO mice had drastically fewer ACF but developed a similar number of tumors as their littermate controls. Expression of genes important in inflammatory colorectal cancer and those relevant to epithelial barrier function was assessed, in addition to structural differences via tissue histology. Our findings point to Selenof's potential role in intestinal barrier integrity and structural changes in glandular and mucin-producing goblet cells in the mucosa and submucosa, which may determine the type of tumor developing.

Clinical characterization and cytokine profile of fatigue in hematologic malignancy patients with chronic graft-versus-host disease.

Limited information is available regarding clinical and biological properties of fatigue in patients with chronic graft-versus-host disease (cGvHD). Patients with moderate-to-severe cGvHD per NIH criteria were enrolled on a cross-sectional study and categorized as "fatigued" if SF-36 vitality score was <40. Clinical and laboratory parameters of fatigued (n = 109) and nonfatigued patients (n = 72) were compared. In univariate analysis, walk velocity, NIH joint-fascia score, human activity profile, and SF-36 physical and mental health self-report scales were correlates of fatigue. No cGvHD biomarkers were associated with fatigue. NIH joint score, Lee sleep and depression questions, and PG-SGA activities and function score jointly predicted fatigue. Though higher rates of depression and insomnia were reported in the fatigued group, antidepressant or sleep aid use did not differ between groups. Survival ratio was not significantly different by fatigue status. Pathophysiology of fatigue in patients with cGvHD is complex and may involve mechanisms unrelated to disease activity. Patients with cGvHD experiencing fatigue had higher rates of untreated depression and insomnia, highlighting the need to focus clinical management of these conditions to improve health-related quality of life.

Circulating Inflammation Proteins Associated With Lung Cancer in African Americans.

INTRODUCTION: Lung cancer incidence is higher among African Americans (AAs) compared with European Americans (EAs) in the United States. We and others have previously shown a relationship between immune and inflammation proteins with lung cancer in EAs. Our aim was to investigate the etiologic relationship between inflammation and lung cancer in AAs. METHODS: We adopted a two-stage, independent study design (discovery cases, n = 316; control cases, n = 509) (validation cases, n = 399; control cases, n = 400 controls) and measured 30 inflammation proteins in blood using Meso Scale Discovery V- PLEX multiplex assays. RESULTS: We identified and validated 10 proteins associated with lung cancer in AAS, some that were common between EAs and AAs (C-reactive proteins [OR: 2.90; 95% confidence interval (CI): 1.99-4.22], interferon γ [OR: 1.55; 95% CI: 1.10-2.19], interleukin 6 [OR: 6.28; 95% CI: 4.10-9.63], interleukin 8 [OR: 2.76; 95% CI: 1.92-3.98]) and some that are only observed among AAs (interleukin 10 [OR: 1.69; 95% CI: 1.20-2.38], interleukin 15 [OR: 2.83; 95% CI: 1.96-4.07], interferon gamma-induced protein 10 [OR: 1.54; 95% CI: 1.09-2.18], monocyte chemotactic protein-4 [OR: 0.54; 95% CI: 0.38-0.76], macrophage inflammatory protein-1 alpha [OR: 1.57; 95% CI: 1.12-2.21], and tumor necrosis factor ß [OR: 0.52; 95% CI: 0.37-0.74]). We did not find evidence that either menthol cigarette smoking or global genetic ancestry drove these population differences. CONCLUSIONS: Our results highlight a distinct inflammation profile associated with lung cancer in AAs compared with EAs. These data provide new insight into the etiology of lung cancer in AAs. Further work is needed to understand what drives this relationship with lung cancer and whether these proteins have utility in the setting of early diagnosis.

Relationship between Circulating Inflammation Proteins and Lung Cancer Diagnosis in the National Lung Screening Trial.

BACKGROUND: Previously, we observed a strong relationship between circulating serum inflammation proteins in relation to lung cancer diagnosis and risk, both in case-control and prospective cohorts. Low-dose computed tomography (LDCT) screening has a high prevalence of false-positive nodules, thus companion noninvasive biomarkers that can distinguish between benign and malignant nodules could have clinical utility and positive impact on patient outcomes. METHODS: We conducted a nested case-control study within the National Lung Screening Trial. Concentrations of 30 inflammation proteins were measured on plasma samples of 262 cases and 528 controls using a highly sensitive and analytically validated electrochemiluminescence V-PLEX immunoassay. RESULTS: Comparing the fourth quartile with the first quartile, we found increased IFNγ and IL12/IL23p40 associated with increased odds of a lung cancer diagnosis [OR 1.89, 95% confidence intervals (CI), 1.16-3.09; OR 2.49, 95% CI, 1.46-4.23, respectively]. Confirming our previous observations, we also detected a relationship between increased IL6, IL8, and C-reactive protein (CRP) with lung cancer diagnosis. These relationships were significant after adjustment for age, gender, race, smoking, body mass index (BMI), family history of lung cancer, and previous diagnoses of inflammatory conditions. However, none of these proteins could distinguish between a benign and malignant lung nodule (IL6: OR 1.25, 95% CI, 0.59-2.64; IL8: OR 1.40, 95% CI, 0.70-2.81; CRP: OR 0.98, 95% CI, 0.45-2.12). CONCLUSIONS: We have discovered new associations for IFNγ and IL12/IL23p40 with lung cancer but have no evidence that these proteins can distinguish between benign and malignant lung nodules. IMPACT: Circulating inflammation proteins are unlikely to have utility as companion LDCT biomarkers.

Megakaryocyte Potentiating Factor as a Predictive Biomarker for Therapies Against Malignant Mesothelioma.

PURPOSE: Effective biomarkers for malignant mesothelioma (MM) are needed for clinical management and the development of mesothelin-targeted therapies. We evaluated serum megakaryocyte potentiating factor (MPF) as a biomarker predictive of treatment outcome in patients with MM and for developing mesothelin-targeted therapies. MATERIALS AND METHODS: Serial serum samples from patients with MM in two clinical trials of an antimesothelin immunotoxin were tested with our clinically validated MPF assay. Correlative studies were performed to determine the test effectiveness in treatment monitoring and outcome prediction. MPF was further evaluated for an association with response to an antimesothelin therapy and for disease monitoring. RESULTS: There was a significant reduction of serum MPF in patients with elevated baseline and radiologic response, with an average change from -52% to -78% after one to six cycles. Using a -50% change as the cutoff, patients with MM with positive MPF response had significantly improved progression-free survival (P < .001), with the median extended from 1.9 to 11.3 months. These patients with MPF response further exhibited improved overall survival (P = .004), with the median extended from 8.8 to 22.3 months. In patients with refractory MM, there was an association between elevated pretreatment serum MPF and radiologic response to an antimesothelin therapy (P = .033). Furthermore, in these response patients, serum MPF was monitored between 32.2 and 63.8 months and was found to reflect treatment response and disease progression. CONCLUSION: At a cutoff of -50% change after receiving systemic therapies, a reduction in MPF was associated with improved clinical outcome, both progression-free survival and overall survival. An elevated baseline serum MPF was associated with a response to an antimesothelin therapy in patients with refractory MM; however, this finding needs to be confirmed in another study.

Elevated Serum Megakaryocyte Potentiating Factor as a Predictor of Poor Survival in Patients with Mesothelioma and Primary Lung Cancer.

Background: There is an urgent need for a companion assay to work with mesothelin-targeted therapeutic agents and for noninvasive and accurate prognostication of malignant mesothelioma (MM) patients. We report the development and validation of a blood-based assay for megakaryocyte potentiating factor (MPF) and the evaluation of its effectiveness for prognosis in MM and lung cancer patients. Methods: Using electrochemiluminescence technology, we developed a sensitive MPF assay and performed both analytical and clinical validations. Further, the effectiveness of the MPF assay in predicting prognosis was evaluated for 95 MM and 272 lung cancer patients. Results: We performed comprehensive analytical and clinical validation, including precision and accuracy, interference, preanalytical variables, sensitivity, and specificity for mesothelioma. In MM patients, increased serum MPF is a predictor of poor survival with a hazard ratio (HR) = 2.46 (log-rank P = 0.003; n = 95). In refractory MM patients, increased MPF is a strong predictor of poor outcome with an HR = 6.12 (log-rank P = 0.0007; n = 57). In a lung cancer patient cohort, increased MPF is a predictor of poor survival, with an HR = 1.57 (log-rank P = 0.003; n = 272). Conclusions: The MPF assay has robust technical characteristics, with strong analytic and clinical validation. Clinical studies indicate that increased serum MPF is a predictor of poor survival for MM patients, throughout the course of the disease. Increased MPF is also associated with poor overall survival for patients with newly diagnosed lung cancer.

Phase I and Preliminary Phase II Study of TRC105 in Combination with Sorafenib in Hepatocellular Carcinoma.

Purpose: Endoglin (CD105) is an endothelial cell membrane receptor highly expressed on proliferating tumor vasculature, including that of hepatocellular carcinoma (HCC), and is associated with poor prognosis. Endoglin is essential for angiogenesis, and its expression is induced by hypoxia and VEGF pathway inhibition. TRC105 is a chimeric IgG1 CD105 mAb that inhibits angiogenesis and causes antibody-dependent cellular cytotoxicity and apoptosis of proliferating endothelium.Experimental Design: Patients with HCC (Child-Pugh A/B7), ECOG 0/1, were enrolled in a phase I study of TRC105 at 3, 6, 10, and 15 mg/kg every 2 weeks given with sorafenib 400 mg twice daily. Correlative biomarkers included DCE-MRI and plasma levels of angiogenic factors, including soluble endoglin. Pharmacokinetics were assessed in serum.Results: Twenty-six patients were enrolled, of whom 25 received treatment, 15 with cirrhosis. Hep B/C: 3/15; M:F 19:6; mean age of 60 (range, 18-76); 1 DLT (grade 3 AST) occurred at 10 mg/kg. The most frequent toxicity was low-grade epistaxis, a known toxicity of TRC105. One patient experienced an infusion reaction and was replaced. One patient with coronary stenosis developed a fatal myocardial infarction, and one patient developed G3 cerebral tumor hemorrhage. MTD was not established and DL4 (15 mg/kg) was expanded. The overall response rate in 24 evaluable patients at all 4 dose levels was 21% [95% confidence interval (CI), 7.1-42.2], and 25% (95% CI, 8.7-49.1) in patients with measureable disease. Four patients had confirmed stable disease, one of whom was treated for 22 months. Median progression-free survival (PFS) for 24 patients evaluable for PFS was 3.8 months (95% CI, 3.2-5.6 months); median overall survival was 15.5 months (95% CI, 8.5-26.3 months).Conclusions: TRC105 combined with sorafenib was well tolerated at the recommended single agent doses of both drugs. Encouraging evidence of activity to date (PR rate 25%) was observed, and the study is now continuing to recruit in the phase II stage as a multicenter study to confirm activity of the combination. Clin Cancer Res; 23(16); 4633-41. ©2017 AACR.

Identification of serum inflammatory markers as classifiers of lung cancer mortality for stage I adenocarcinoma.

BACKGROUND: Lung cancer is the leading cause of cancer-related mortality worldwide. Low-dose CT (LDCT) imaging is now recommended to screen high-risk lung cancer individuals in the USA. LDCT has resulted in increased detection of stage I lung cancer for which the current standard of care is surgery alone. However, approximately 30% of these patients develop recurrence and therefore are in need of further treatment upon diagnosis. This study aims to explore blood-based inflammatory biomarkers to identify patients at high-risk of mortality for which additional treatment modalities can be offered at time of diagnosis. PATIENTS AND METHODS: Recent work on a small panel of circulating cytokines identified elevated levels of IL-6, a pro-inflammatory cytokine, as an indicator of poor survival for lung cancer patients. To reflect the broader role of inflammation in lung cancer, we examined a large panel of 33 inflammatory proteins in the sera of 129 lung cancer patients selected from the National Cancer Institute-Maryland case-control study. To reduce heterogeneity, we specifically focused our study on stage I lung adenocarcinoma patients. RESULTS: We replicated the previous observations that IL-6 is associated with prognosis of lung cancer and extended its utility to prognosis in this highly-selected population of stage I lung adenocarcinoma patients. In addition, we developed a multi-marker, combined prognostic classifier that includes the pro-inflammatory Th-17 cell effector cytokine, IL-17. Patients with high levels of IL-6 and IL-17A had a significantly adverse survival compared with patients with low levels (P for trend <0.0001). Patients in the high risk group, with high levels of both proteins had a 5-year survival rate of 46% in comparison to 93% for those with low levels of both markers. Furthermore, we validated the same trends for the IL-6 and IL-17A prognostic signature in an independent data set. CONCLUSIONS: The results identified here justify further investigation of this novel, combined cytokine prognostic classifier for the identification of high-risk stage I lung adenocarcinoma patients. This classifier has the much-needed potential to identify patients at high risk of recurrence and thus prospectively identify the subset of patients requiring more aggressive treatment regimens at the time of diagnosis.

A Phase II Clinical Trial of TRC105 (Anti-Endoglin Antibody) in Adults With Advanced/Metastatic Urothelial Carcinoma.

BACKGROUND: In this trial we assessed the efficacy and tolerability of TRC105, a chimeric monoclonal antibody that targets CD105 (endoglin) in patients with advanced, previously treated urothelial carcinoma (UC). PATIENTS AND METHODS: Patients received TRC105 15 mg/kg every 2 weeks on days 1 and 15 of each 28-day cycle. The primary end point was progression-free survival (PFS) at 6 months. Secondary end points included safety, toxicity, and overall survival (OS). CD105 expression was evaluated using immunohistochemistry (IHC) in a separate cohort of 50 UC patients. Biomarker studies included immune subsets, circulating tumor cells (CTCs), circulating endothelial cells (CECs), circulating endothelial progenitor cells (CEPs), and osteopontin. RESULTS: Of 13 patients enrolled, 12 were evaluable for OS and PFS. The 3-month PFS probability was 18.2% (median PFS, 1.9 months [95% confidence interval (CI), 1.8-2.1 months). This met the criterion for ending accrual on the basis of the 2-stage design. Median OS was 8.3 months (95% CI, 3.3-17.0 months). IHC for CD105 scores was not associated with T stage (P = .26) or presence of lymph nodes (P = .64). Baseline levels of regulatory T and B cells, CEPs, and changes in CEC level after TRC105 exhibited trends toward an association with PFS or OS. CTCs pre- and post-TRC105 were detected in 4 of 4 patients. CONCLUSION: Although TRC105 was well tolerated, it did not improve 6-month PFS in heavily pretreated patients with advanced UC. CD105 staining was present in 50% of UC tumors at different intensities. Our observations on the pharmacodynamic significance of immune subsets, CECs, and CTCs warrant further study.

Caspase-8 expression is predictive of tumour response to death receptor 5 agonist antibody in Ewing's sarcoma.

BACKGROUND: Despite good initial response to chemotherapy, 30% of Ewing's sarcoma (EWS) patients with localised tumours develop recurrent disease, associated with poor prognosis. The aim of this study was to address this challenge by conducting preclinical evaluation of a death receptor targeted agent in vitro and in vivo, and by identifying predictive biomarkers. METHODS: Cell viability assays, drug dose responses, immunoblots, rescue with gene transfer, mice tumour models, and statistical comparisons of tumour growth and Kaplan-Meier survival curves. RESULTS: This study shows that many EWS cell lines are selectively sensitive to a death receptor DR5 antibody and are more resistant to a DR4 antibody. Preclinical evaluation of these cell lines indicates their sensitivity to human DR5 agonist antibody conatumumab in vitro, which induces rapid activation of caspase-8 and apoptosis. We also found that sensitivity to conatumumab correlates with expression of caspase-8. Furthermore, the catalytic activity of caspase-8 is both necessary and sufficient to confer this sensitivity. In vivo, conatumumab is active against an EWS cell line and a patient-derived xenograft with higher caspase-8 expression, but is not effective against another with lower caspase-8 expression. CONCLUSIONS: These studies suggest the potential of conatumumab as a therapeutic agent against EWS and caspase-8 as a predictive biomarker for sensitivity.

A phase I study of TRC105 anti-endoglin (CD105) antibody in metastatic castration-resistant prostate cancer.

OBJECTIVE: TRC105 is a chimeric immunoglobulin G1 monoclonal antibody that binds endoglin (CD105). This phase I open-label study evaluated the safety, pharmacokinetics and pharmacodynamics of TRC105 in patients with metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS: Patients with mCRPC received escalating doses of i.v. TRC105 until unacceptable toxicity or disease progression, up to a predetermined dose level, using a standard 3 + 3 phase I design. RESULTS: A total of 20 patients were treated. The top dose level studied, 20 mg/kg every 2 weeks, was the maximum tolerated dose. Common adverse effects included infusion-related reaction (90%), low grade headache (67%), anaemia (48%), epistaxis (43%) and fever (43%). Ten patients had stable disease on study and eight patients had declines in prostate specific antigen (PSA). Significant plasma CD105 reduction was observed at the higher dose levels. In an exploratory analysis, vascular endothelial growth factor (VEGF) was increased after treatment with TRC105 and VEGF levels were associated with CD105 reduction. CONCLUSION: TRC105 was tolerated at 20 mg/kg every other week with a safety profile distinct from that of VEGF inhibitors. A significant induction of plasma VEGF was associated with CD105 reduction, suggesting anti-angiogenic activity of TRC105. An exploratory analysis showed a tentative correlation between the reduction of CD105 and a decrease in PSA velocity, suggestive of potential activity of TRC105 in the patients with mCRPC. The data from this exploratory analysis suggest that rising VEGF level is a possible compensatory mechanism for TRC105-induced anti-angiogenic activity.

Cixutumumab for patients with recurrent or refractory advanced thymic epithelial tumours: a multicentre, open-label, phase 2 trial.

BACKGROUND: No standard treatment exists for refractory or relapsed advanced thymic epithelial tumours. We investigated the efficacy of cixutumumab, a fully human IgG1 monoclonal antibody targeting the insulin-like growth factor 1 receptor in thymic epithelial tumours after failure of previous chemotherapy. METHODS: Between Aug 25, 2009, and March 27, 2012, we did a multicentre, open-label, phase 2 trial in patients aged 18 years or older with histologically confirmed recurrent or refractory thymic epithelial tumours. We enrolled individuals who had progressed after at least one previous regimen of platinum-containing chemotherapy, had an Eastern Cooperative Oncology Group performance status of 0 or 1, and had measurable disease and adequate organ function. Eligible patients received intravenous cixutumumab (20 mg/kg) every 3 weeks until disease progression or development of intolerable toxic effects. The primary endpoint was the frequency of response, analysed on an intention-to-treat basis. We also did pharmacodynamic studies. This trial is registered with ClinicalTrials.gov, number NCT00965250. FINDINGS: 49 patients were enrolled (37 with thymomas and 12 with thymic carcinomas) who received a median of eight cycles of cixutumumab (range 1-46). At the final actuarial analysis when follow-up data were updated (Nov 30, 2012), median potential follow-up (from on-study date to most current follow-up date) was 24·0 months (IQR 17·3-36·9). In the thymoma cohort, five (14%) of 37 patients (95% CI 5-29) achieved a partial response, 28 had stable disease, and four had progressive disease. In the thymic carcinoma cohort, none of 12 patients (95% CI 0-26) had a partial response, five had stable disease, and seven had progressive disease. The most common grade 3-4 adverse events in both cohorts combined were hyperglycaemia (five [10%]), lipase elevation (three [6%]), and weight loss, tumour pain, and hyperuricaemia (two each [4%]). Nine (24%) of 37 patients with thymoma developed autoimmune conditions during treatment (five were new-onset disorders), the most common of which was pure red-cell aplasia. Two (4%) patients died; one was attributed to disease progression and the other to disease-related complications (respiratory failure, myositis, and an acute coronary event), which could have been precipitated by treatment with cixutumumab. INTERPRETATION: Cixutumumab monotherapy is well-tolerated and active in relapsed thymoma. Development of autoimmunity during treatment needs further investigation. FUNDING: Division of Cancer Treatment and Diagnosis at the National Cancer Institute (National Institutes of Health), ImClone Systems.

Efficacy of anti-insulin-like growth factor I receptor monoclonal antibody cixutumumab in mesothelioma is highly correlated with insulin growth factor-I receptor sites/cell.

Insulin growth factor-I receptor (IGF-IR) is expressed in mesothelioma and therefore an attractive target for therapy. The antitumor activity of cixutumumab, a humanized monoclonal antibody to IGF-IR, in mesothelioma and relationship to IGF-IR expression was investigated using eight early passage tumor cells obtained from patients, nine established cell lines and an in vivo human mesothelioma tumor xenograft model. Although IGF-IR expression at the mRNA and protein level was present in all mesothelioma cells, using a quantitative ELISA immunoassay, there was considerable variability of IGF-IR expression ranging from 1 to 14 ng/mg of lysate. Using flow cytometry, the number of IGF-IR surface receptors varied from ≈ 2,000 to 50,000 sites/cell. Cells expressing >10,000 sites/cell had greater than 10% growth inhibition when treated with cixutumumab (100 µg/ml). Cixutumumab also induced antibody-dependent cell-mediated toxicity (>10% specific lysis) in cell lines, which had >20,000 IGF-IR sites/cell. Treatment with cixutumumab decreased phosphorylation of IGF-IR, Akt and Erk in cell lines, H226 and H28 having 24,000 and 51,000 IGF-IR sites/cell, respectively, but not in the cell line H2052 with 3,000 IGF-IR sites/cell. In vivo, cixutumumab treatment delayed growth of H226 mesothelioma tumor xenografts in mice and improved the overall survival of these mice compared to mice treated with saline (p < 0.004). Our results demonstrate that the antitumor efficacy of cixutumumab including inhibition of IGF-IR downstream signaling is highly correlated with IGF-IR sites/cell. A phase II clinical trial of cixutumumab is currently ongoing for the treatment of patients with mesothelioma.

Phase I study of the synthetic triterpenoid, 2-cyano-3, 12-dioxoolean-1, 9-dien-28-oic acid (CDDO), in advanced solid tumors.

BACKGROUND: The triterpenoid 2-cyano-3,12-dioxoolean-1,9-dien-28-oic Acid (CDDO, previously RTA 401) is a multifunctional molecule that controls cellular growth and differentiation. While CDDO is capable of activating the transcription factor peroxisome proliferator activator receptor-γ (PPARγ), its apoptotic effects in malignant cells have been shown to occur independently of PPARγ. A phase I dose-escalation study was conducted to determine the toxicity, the maximum tolerated dose, and the pharmacokinetics and pharmacodynamics of CDDO, administered as a 5-day continuous infusion every 28 days in patients with advanced cancers. METHODS: An accelerated titration design was followed, with one patient per cohort entered, and doses ranging from 0.6 to 38.4 mg/m(2)/h. Pharmacokinetics of CDDO was assessed and cleaved poly (ADP-ribose) polymerase (c-PARP), as a marker of apoptosis, was measured in peripheral blood mononuclear cells to assess drug effect. RESULTS: Seven patients, one patient per dose level up to dose level 7 (38.4 mg/m(2)/h), were enrolled and received a total of 11 courses of treatment. Cmax increased proportionally with dose. Preclinically determined efficacious blood level (1 µM) of drug was attained at the highest dose level. One patient, at dose level 6, experienced grade 2 mucositis, nausea, vomiting, and anorexia. Four patients developed thromboembolic events subsequently considered as dose-limiting toxicity. No antitumor activity was noted. CONCLUSION: A causal relationship of observed thromboembolic events to CDDO was considered possible but could not be established.

T-cell differentiation factor CBF-ß regulates HIV-1 Vif-mediated evasion of host restriction.

The human APOBEC3 cytidine deaminases are potent inhibitors of diverse retroviruses, including human immunodeficiency virus-1 (HIV-1). HIV-1 Vif forms an E3 ubiquitin ligase complex with cullin 5 (CUL5), elongin B and elongin C , which promotes the polyubiquitination and degradation of APOBEC3 substrates. Here we demonstrate in human T cells that core binding factor ß (CBF-ß) is a key regulator of the evasion of HIV-1 from the host defence mediated by APOBEC3. CBF-ß, the non-DNA-binding subunit of a heterodimeric transcription factor, regulates the folding and DNA-binding activity of partner RUNX family proteins, which have important roles in the development and differentiation of diverse cell types, including T lymphocytes. In our study, knockdown of endogenous CBF-ß blocked Vif-induced APOBEC3G polyubiquitination and degradation. CBF-ß was not required for the interaction between Vif and APOBEC3G, yet was essential for the assembly of the Vif-CUL5 E3-ubiquitin-ligase complex. CBF-ß proved to be a unique regulator of primate lentiviral Vif and not a general component of the CUL5 E3 ubiquitin ligase. We show that Vif and CBF-ß physically interact, and that the amino-terminal region of Vif is required for this interaction. Furthermore, interactions with Vif required regions in CBF-ß that are not involved in RUNX protein binding. Considering the importance of the interaction between Vif and CBF-ß, disrupting this interaction represents an attractive pharmacological intervention against HIV-1.

Drozitumab, a human antibody to death receptor 5, has potent antitumor activity against rhabdomyosarcoma with the expression of caspase-8 predictive of response.

PURPOSE: Rhabdomyosarcoma (RMS) is a common pediatric soft-tissue tumor. In this study, we evaluated the efficacy and selectivity of drozitumab, a death receptor DR5-targeted therapeutic antibody, in RMS preclinical models. EXPERIMENTAL DESIGN: A panel of 11 RMS cell lines was used for in vitro studies. The molecular marker predictive of response to drozitumab was interrogated. Selected RMS cell lines were injected into the gastrocnemius muscle of mice for in vivo assessment of the potency and selectivity of drozitumab. RESULTS: We report that DR5, but not DR4, persisted at high levels and on the surface of all RMS cell lines. DR5 antibody drozitumab was effective in vitro against the majority of RMS cell lines. There was a strong correlation between caspase-8 expression and the sensitivity to drozitumab, which induced the rapid assembly of the death-induced signaling complex and the cleavage of caspase-8 only in sensitive cells. More importantly, caspase-8 catalytic activity was both necessary and sufficient for mediating the sensitivity to drozitumab. Furthermore, drozitumab had potent antitumor activity against established RMS xenografts with a specificity predicted from the in vitro analysis and with tumor-free status in half of the treated mice. CONCLUSION: Our study provides the first preclinical evaluation of the potency and selectivity of a death receptor antibody in RMS. Drozitumab is effective, in vitro, against the majority of RMS cell lines that express caspase-8 and, in vivo, may provide long-term control of RMS.