Future approaches in immunotherapy

Advances in our understanding of the complex mechanisms of immune regulation and the interactions between tumor cells and the immune system have provided a solid foundation for advancing cancer immunotherapy and have inspired novel therapeutic strategies. Optimizing the effectiveness of immunotherapy will require targeting the antitumor immune response at multiple levels, and this may be achieved through synergistic combinations. Examples include combining two cancer vaccines to achieve a "prime and boost" effect, combining two immune checkpoint inhibitors, combining immunotherapy with targeted agents, or combining immunotherapy with low-dose chemotherapy or radiation. Immune checkpoint inhibitors, such as ipilimumab and nivolumab, will likely play an important role in the future of immunotherapy. The ability to block key pathways by which tumor cells seek to evade or suppress the immune response is critical to realizing the potential of cancer immunotherapy. Other exciting advances include recombinant oncolytic viruses and adoptive transfer of chimeric antigen receptor T cells. However, many challenges remain if durable tumor eradication with minimal toxicity is to be achieved in a broader population of cancer patients.

A phase I/II study of lenalidomide in combination with sunitinib in patients with advanced or metastatic renal cell carcinoma

BACKGROUND

This phase I/II study was conducted to determine the maximum tolerated dose (MTD), safety, and efficacy of lenalidomide plus sunitinib in metastatic renal cell carcinoma (RCC) patients.

PATIENTS AND METHODS

Patients with histologically confirmed, metastatic RCC were treated with 10 mg/day lenalidomide plus 37.5 mg/day sunitinib, orally in 21-day cycles. Doses were escalated to determine the MTD in phase I, with additional patients planned at this dose in phase II. Primary end points were MTD and response rate.

RESULTS

Sixteen patients received a median of 2, 3, and 5 cycles in cohort 1 [lenalidomide 10 mg (days 1-21) and sunitinib 37.5 mg (days 1-21)], cohort 2 [lenalidomide 10 mg (days 1-21) and sunitinib 37.5 mg (days 1-14)], and cohort 3 [lenalidomide 15 mg (days 1-21) and sunitinib 37.5 mg (days 1-14)], respectively. Median treatment durations were 41, 63, and 97 days for lenalidomide; and 41, 57, and 97.5 days for sunitinib. The MTD was found to be continuous dosing of lenalidomide 10 mg/day plus sunitinib 37.5 mg/day for 14 of 21 days. Dose-limiting toxicities included neutropenia, leukopenia, thrombocytopenia, asthenia, atrial fibrillation, and increased transaminases. The most frequent grade 3-4 treatment-emergent adverse events were hematologic, including neutropenia and leukopenia. One patient achieved partial response, and seven had stable disease of which three were confirmed at subsequent tumor assessments. B cells and several T-cell subsets were modulated versus baseline.

CONCLUSION

The dose schedules of lenalidomide and sunitinib evaluated in this study were not well tolerated; cumulative toxicity precluded enrollment at the MTD.

Practice challenges affecting optimal care as identifed by US medical oncologists who treat renal cell carcinomas

BACKGROUND

Approval of new agents provides alternative treatment options for medical oncologists and their patients with renal cell carcinoma (RCC). Treatment decisions remain challenging in the absence of clear evidence supporting optimal selection and sequencing of treatment for different patient or tumor characteristics.

OBJECTIVE

To assess the clinical practice gaps of medical oncologists treating patients with RCC.

METHODS

Medical oncologists practicing in the United States with a case load of 1 or more RCC patient(s) a year were recruited to participate in either an online case-based survey followed by a 45-minute interview (phase 1) or a 15-minute online survey with case vignettes (phase 2). Respondents' answers were compared with treatment guidelines and faculty experts' recommendations.

RESULTS

Qualitative interviews (n = 27) and quantitative surveys (n = 142) were compiled. Clinical performance gaps demonstrating oncologists' diffculties to optimally adjust their treatment plan were identifed. When presented with an RCC patient with treatment-related hypertension, 34% of respondents did not select an expert-recommended option. In a scenario focused on recognizing clinical signs and symptoms as an important component of treatment decision-making, 40% of respondents agreed with the expert-recommended approach. For a progressive patient with chronic obstructive pulmonary disease, 78% of respondents were misaligned with evidence-based treatment options.

LIMITATIONS

Self-selection and respondent bias may have occurred. Sample size may have limited the statistical power.

CONCLUSIONS

This study identifed clinically relevant performance gaps among US oncologists treating RCC patients. Education to assure familiarity with the most recent changes is needed.

FUNDING/SPONSORSHIP

Pfzer Medical Education Group provided fnancial support through an educational research grant.

The myeloid receptor TREM2 exacerbates DSS-induced colitis and promotes colitis-associated cancer (TUM4P.916)

The Triggering Receptors Expressed on Myeloid cells (TREM) gene cluster contains receptors that regulate a variety of leukocytes. TREM1 synergizes with Toll Like Receptors to promote cytokine production in neutrophils, macrophages and dendritic cells (DC). Paradoxically, although TREM1 and TREM2 both signal via DAP12, TREM2 is a negative regulator of inflammation in macrophages and DC. TREM2 is expressed in the colon but its role in colitis and colitis-associated cancer (CAC) is poorly understood. We found TREM2 expressed in monocytic myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM). Moreover, TAM expressed a apparent TREM2 ligand. To test the role of TREM2 in inflammation-induced cancer we studied the azoxymethane (AOM)-dextran sulfate sodium (DSS)-induced model of CAC. DSS administration led a pronounced influx of myeloid cells and upregulation of both TREM1 and TREM2. Surprisingly, we found that Trem2-/- mice had less severe colitis as indicated by reduced histological scores, colon shortening and inflammatory cytokine production in the colon. AOM-DSS carcinogenesis in Trem2-/- mice resulted in slightly reduced total polyp counts and mitotic epithelial cells but a substantial reduction in the numbers of advanced carcinomas compared to wild type mice. Taken together, our data suggest an important role for TREM2 in the regulation of colitis and CAC likely via control of epithelial proliferation during colonic injury and inflammation.

Angiogenesis and the tumor microenvironment: vascular endothelial growth factor and beyond

Our understanding of the dynamic tumor microenvironment (TME) has improved exponentially over the last few decades. In addition to traditional cytotoxic agents, anti-cancer strategies now include numerous molecular-targeted drugs that modulate distinct elements of the TME. Angiogenesis is an underlying promoter of tumor growth, invasion, and metastases. From traditional and emerging angiogenic cytokines and their receptors to novel immune checkpoint inhibitors, regulation of the tumor microenvironment is potentially key in countering tumor progression. In this article, an overview of the architecture of the TME and the orchestration of angiogenesis within the TME is provided. Additionally, traditional and novel angiogenic targets of current interest within the TME are reviewed.

Progression-free survival as a surrogate endpoint of overall survival in patients with metastatic renal cell carcinoma

BACKGROUND

The current study was conducted to investigate the dependence between progression-free survival (PFS) and overall survival (OS) in patients with metastatic renal cell carcinoma (mRCC) and to explore whether PFS can be used as an intermediate endpoint of OS in this patient population.

METHODS

A total of 1381 patients from 2 prospective phase 3 trials (Cancer and Leukemia Group B [CALGB] 90206 and AVOREN) of interferon-alpha with or without bevacizumab were analyzed. Both trials recruited previously untreated patients with clear cell mRCC with an Eastern Cooperative Oncology Group performance status of 0 to 2; adequate bone marrow, hepatic, cardiac, and renal function; and controlled blood pressure. The CALGB study served as the training data set, and the AVOREN study served as the testing data set. The dependence between PFS and OS was investigated using the Kendall tau for bivariate time-to-event endpoints.

RESULTS

In the training data set, the median OS times among patients who experienced progressive disease at 3 months or 6 months were 6 months and 8 months, respectively, compared with 25 months and 30 months, respectively, (P < .001) in patients who did not develop disease progress. The adjusted hazard ratios (HR) were 2.6 (P < .0001) and 2.8 (P < .0001), respectively, for patients who did and did not progress at 3 months or 6 months. The dependence between PFS and OS was 0.53. These associations were confirmed in the testing data set.

CONCLUSIONS

In patients with mRCC who were treated with interferon-alpha with or without bevacizumab, the PFS at 3 months and 6 months was found to be predictive of OS. A high dependence between PFS and OS was observed, suggesting that PFS may be used as a surrogate endpoint for OS. Although this is a novel observation for RCC, these findings require validation in patients with mRCC who are treated with other targeted agents.

Abstract 1184: The effect of dual VEGF/VEGFR inhibition on angiogenic signaling pathways

Background: The vascular endothelial growth factor (VEGF) antibody bevacizumab (Bev) and VEGF receptor (VEGFR) inhibitor sunitinib are efficacious agents in many solid tumors. Non-VEGF angiogenic molecules are postulated as a resistance mechanism against VEGF agents, but these pathways are incompletely understood. Angiogenic proteins were characterized in patients treated with dual VEGF/VEGFR inhibition.

Methods: Patients with metastatic tumors were enrolled on a phase I trial of sunitinib (37.5 mg daily from weeks 1-4) and Bev (5 mg/kg on days 1, 15 and 29) of a 6 week cycle. Angiogenic proteins were quantified in serum samples at baseline, 4 and 6 weeks using ELISA assays (R&D Systems, Antibody On Line and IBL American).

Results: Samples were collected from 13 patients (10 melanoma, 1 angiosarcoma, 1 adrenal and 1 renal cell carcinoma). Dual VEGF/VEGFR inhibition resulted in reduction of soluble (s) VEGFR-2, sVEGFR-3, sTIE-2, Angiopoeitin (Ang)-2 and MMP-9 from baseline to week 4 (See table-1). There was a significant increase in prokineticin-2 at week 4 versus baseline. During the “off-period” of sunitinib from week 4 to 6, sVEGFR-2 and sVEGFR-3 increased. Continued Bev during the off-period resulted in reduction of sVEGF but increase in circulating Ang-2 and sTIE-2.

Discussion: These data support the biological basis of dual VEGF/VEGFR inhibition given the lack of rebound VEGF increase during the sunitinib off-period with continued Bev. Consistent with pre-clinical evidence implicating VEGF signaling in MMP-9 regulation, MMP-9 was down-regulated with VEGF/VEGFR inhibition. Dual VEGF/VEGFR inhibition resulted in decrease in Ang-2 and its receptor TIE-2, which subsequently increased during the sunitinib off period. Up regulation of prokineticin-2, predicted by preclinical studies to mediate Bev resistance, has not previously been identified in patients. Future research will elucidate the mechanistic roles of non VEGF proteins in mediating resistance to antiangiogenic agents.

Table 1: Markers of angiogenesis in patients treated with dual VEGF/VEGFR inhibition Median level Baseline (n = 13) Median level week 4 (n = 13) Median level week 6 (n = 9) p value baseline vs week 4 p value baseline vs week 6 p value week 4 vs week 6 sVEGF (pg/ml) 360.67 217.19 167.66 0.07 0.03 0.004 sVEGFR1 (pg/ml) 109.32 149.33 117.35 1.0 0.30 0.50 sVEGFR2 (pg/ml) 1856.1 1264 1393.1 0.0002 0.004 0.03 sVEGFR3 (ng/ml) 45.04 15.38 23.66 0.0002 0.004 0.004 sTIE-2 (ng/ml) 20.77 15.48 17.42 0.0002 0.004 0.03 Angiopoeitin-2 (pg/ml) 2841.4 1537.2 1843.8 0.0002 0.004 0.04 MMP-9 (ng/ml) 609.3 312.8 363.6 0.01 0.03 0.25 Prokineticin-1 (ng/ml) 0.615 0.646 0.54 0.22 1.0 0.57 Prokineticin-2 (pg/ml) 0.35 3.95 0.83 0.01 0.11 0.43

Citation Format: Kriti Mittal, Henry Koon, Paul Elson, Pierre Triozzi, Afshin Dowlati, Ernest Borden, Brian Rini. The effect of dual VEGF/VEGFR inhibition on angiogenic signaling pathways. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1184. doi:10.1158/1538-7445.AM2013-1184

Abstract SY27-03: Biomarker-guided development of novel multi-peptide cancer vaccines - from discovery to phase lll trials

Translational research and the clinical development of therapeutic cancer vaccines require strong scientific rationale in order to better understand the mode-of-action and to incorporate the lessons learned in the optimization of cancer vaccines by (i) selecting appropriate immunomodulators to generate more effective vaccine regimens, (ii) combining vaccine regimens and standard-of-care therapeutics with synergistic potential and (iii) identifying patient populations that may have a better chance of responding to the vaccine.

Here we demonstrate how preclinical and clinical immune response markers combined with cellular and serum biomarkers that define the immune regulatory environment were utilized as guiding tools in the development of three novel multi-peptide vaccines in renal cell cancer (IMA901), colorectal cancer (IMA910) and glioblastoma (IMA950).

All three vaccine products comprise multiple tumor-associated peptides (TUMAPs) confirmed, by mass spectrometry, to be naturally presented in human cancer tissue. Each vaccine was selected using differential transcriptomics approaches and validated by in vitro analysis of immunogenicity with artificial antigen-presenting cells followed by in vivo analysis of immune responses in clinical trials. The vaccines contain HLA class I and II-restricted peptides designed to elicit CD8+ cytotoxic and CD4+ helper T-cell responses, respectively.

IMA901 is a novel renal cell cancer (RCC) vaccine consisting of 9 HLA class I and 1 HLA class II TUMAPs with the majority of peptides confirmed to be naturally presented on and shared between RCC tissues. Consecutive independent Phase I and II clinical studies were conducted in HLA-A*02+ advanced/metastatic RCC patients (total 96) receiving repeated intradermal vaccinations with IMA901 plus human granulocyte-macrophage colony-stimulating factor (GM-CSF). The two studies demonstrated an association between overall survival and multiple vaccine-induced T-cell responses and an impact of single-dose cyclophosphamide (300 mg/m2) on regulatory T cells (Tregs) and overall survival. Furthermore, two myeloid-derived suppressor cell (MDSC) populations (CD14+ HLA-DR−/low and CD14− CD11b+ CD15+) were significantly negatively associated with survival in vaccinated RCC patients.

The knowledge acquired in these trials was used to design a randomized, controlled Phase III study. Recruitment of 339 advanced/metastatic first-line RCC patients was recently completed. IMA901 is combined with the tyrosine kinase inhibitor sunitinib based on the findings that sunitinib down-modulates the two MDSC populations described above. Furthermore, in this Phase III study, the relevance of two serum biomarkers (Apoliprotein A1 and CCL17) found in the Phase II study to be associated with immune response and OS will be prospectively explored (Walter, Weinschenk et al., Nat Med 2012).

IMA910 is a novel colorectal cancer (CRC) vaccine consisting of 10 HLA class I and 3 HLA class II TUMAPs with the majority of peptides confirmed to be naturally presented on and shared between CRC tissues. A Phase I/II trial was conducted in 92 HLA-A*02+ advanced colorectal cancer patients with stable (SD) or responding (PR/CR) disease after 12 weeks of first-line oxaliplatin-based therapy. Thereafter, first-line oxaliplatin-based chemotherapy was stopped and patients received a single dose of cyclophosphamide to reduce Tregs followed by repeated intradermal vaccinations with IMA910 plus GM-CSF (first cohort; n=66) with or without topically applied imiquimod (second cohort; n=26). IMA910 elicited immune responses towards multiple class I (in 43% of the subjects) and class II TUMAPs (65%). Similarly to the IMA901 vaccine trial in RCC, such vaccine-induced CD8+ as well as CD4+ T-cell responses to multiple TUMAPs were associated with increased overall survival. Patients who additionally received imiquimod were more often multi-peptide class I responders (p=0.016) as determined by intracellular cytokine staining (ICS) assay and showed a modestly (two-fold) increase of T-cell freqencies (p=0.12) as determined by HLA multimer assay. Interestingly, the same two populations of MDSC as described above in renal cell cancer patients were negatively associated with vaccine-induced immune response and overall survival implying a potential generalized role of these two MDSC populations. Further development of this vaccine is planned in a setting where an MDSC-modulating standard-of-care (e.g. chemotherapy) is applied.

IMA950 is a novel glioblastoma vaccine consisting of 9 HLA class I and 2 HLA class II TUMAPs with the majority of peptides confirmed to be naturally presented on and shared between glioblastoma tissues. A Phase I study sponsored by Cancer Research UK is currently ongoing in the United Kingdom. A total of 45 newly diagnosed glioblastoma patients will be treated. The study is expected to complete recruitment in the first quarter of 2013. The primary objectives of this first-in-man study are to assess the safety, tolerability and immunogenicity of IMA950 plus GM-CSF when given alongside standard chemoradiotherapy followed by adjuvant chemotherapy with temozolomide. Patients enter the trial into one of two cohorts (start of vaccination either prior to or after initial chemoradiotherapy) in order to determine potential differences in the immune response in these two cohorts. First immunomonitoring data indicate a high immune as well as multi-TUMAP response rate in the study population. Updated and unpublished immune data will be presented at the meeting.

Analysis of the in vitro immunogenicity data obtained from healthy donors during the discovery phases of these programs and comparison of these data with the in vivo immunogenicity data obtained in the clinical trials demonstrated that in all four clinical trials in a total of approx. 200 patients the in vitro data correlated with the in vivo data. This implies that such a standardized in vitro assay system may be utilized in future to further optimize vaccine regimens by selecting the most immunogenic novel peptides before entering clinical trials.

In conclusion, we suggest that use of preclinically well characterized naturally presented tumor antigens combined with systematic clinical immunomonitoring and cellular/serum biomarker screening will be helpful to guide rational development of novel cancer vaccines.

Citation Format: Harpreet Singh-Jasuja, Steffen Walter, Toni Weinschenk, Alexandra Kirner, Andrea Mayer-Mokler, Norbert Hilf, Oliver Schoor, Pierre-Yves Dietrich, James Richtie, Roy Rampling, Frank Mayer, Arnulf Stenzl, Brian Rini, Carsten Reinhardt, Hans-Georg Rammensee. Biomarker-guided development of novel multi-peptide cancer vaccines - from discovery to phase lll trials. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr SY27-03. doi:10.1158/1538-7445.AM2013-SY27-03

Pericyte coverage of differentiated vessels inside tumor vasculature is an independent unfavorable prognostic factor for patients with clear cell renal cell carcinoma

BACKGROUND

The objective of this study was to evaluate the effect of pericyte coverage (PC) of differentiated tumor microvessels on the prognosis of patients with clear cell renal cell carcinoma (CCRCC).

METHODS

Samples from 2 cohorts of patients with CCRCC (101 Asian patients and 524 US patients) were prepared using 2 different histologic approaches: routine sectioning versus tissue microarray. Then, the samples were immunohistochemically doubled-stained for a pericyte marker (alpha smooth muscle actin [α-SMA]) and a differentiated vessel marker (cluster of differentiation 34 [CD34]), followed by multispectral image capturing and computerized image analyses to quantify the microvessel density (MVD) and the PC of differentiated vessels. The correlations of PC and the MVD:PC ratio with clinicopathologic characteristics were analyzed.

RESULTS

There was an inverse correlation between differentiated MVD and PC. Higher PC correlated with more aggressive clinicopathologic characteristics of CCRCC in both cohorts, including more advanced T-classification, higher pathologic grades, and the occurrence of tumor necrosis. The MVD:PC ratio was an independent favorable prognostic factor for overall and recurrence-free survival in the Asian cohort and for recurrence-free survival in the US cohort. PC also was an independent prognostic factor, with higher PC predicting a poorer outcome. The combination of PC and MVD was better at distinguishing the outcome of patients with CCRCC. PC combined with differentiated MVD or with the MVD:PC ratio provided additional, independent prognostic information to the Leibovich risk model, and that information was used to generate improved risk models.

CONCLUSIONS

The authors consistently observed that higher PC was correlated with more aggressive clinicopathologic characteristics. PC was an independent unfavorable prognostic factor. The authors concluded that pericytes should be considered for therapeutic targeting.

AMG 386 in combination with sorafenib in patients with metastatic clear cell carcinoma of the kidney: a randomized, double-blind, placebo-controlled, phase 2 study

BACKGROUND

This study evaluated the tolerability and antitumor activity of AMG 386, a peptibody (a peptide Fc fusion) that neutralizes the interaction of angiopoietin-1 and angiopoietin-2 with Tie2 (tyrosine kinase with immunoglobulin-like and EGF-like domains 2), plus sorafenib in patients with clear cell metastatic renal cell carcinoma (mRCC) in a randomized controlled study.

METHODS

Previously untreated patients with mRCC were randomized 1:1:1 to receive sorafenib 400 mg orally twice daily plus intravenous AMG 386 at 10 mg/kg (arm A) or 3 mg/kg (arm B) or placebo (arm C) once weekly (qw). Patients in arm C could receive open-label AMG 386 at 10 mg/kg qw plus sorafenib following disease progression. The primary endpoint was progression-free survival (PFS).

RESULTS

A total of 152 patients were randomized. Median PFS was 9.0, 8.5, and 9.0 months in arms A, B, and C, respectively (hazard ratio for arms A and B vs arm C, 0.88; 95% confidence interval [CI], 0.60-1.30; P = .523). The objective response rate (95% CI) for arms A, B, and C, respectively, was 38% (25%-53%), 37% (24%-52%), and 25% (14%-40%). Among 30 patients in arm C who had disease progression and subsequently received open-label AMG 386 at 10 mg/kg qw, the objective response rate was 3% (95% CI, 0%-17%). Frequently occurring adverse events (AEs) included diarrhea (arms A/B/C, 70%/67%/56%), palmar-plantar erythrodysesthesia syndrome (52%/47%/54%), alopecia (50%/45%/50%), and hypertension (42%/49%/46%). Fifteen patients had grade 4 AEs (arms A/B/C, n = 3/7/5); 4 had fatal AEs (n = 2/1/1), with 1 (abdominal pain, arm B) considered possibly related to AMG 386.

CONCLUSIONS

In patients with mRCC, AMG 386 plus sorafenib was tolerable but did not significantly improve PFS compared with placebo plus sorafenib.

Abstract 4378: Pericyte coverage of differentiated vessels inside tumor vasculature is an independent unfavorable prognostic factor for patients with clear cell renal cell carcinoma

Background: The clinical significance of pericyte coverage (PC) surrounding differentiated vessels in clear cell renal cell carcinoma (CCRCC) is unclear. Objective: To evaluate the effect of PC on the prognosis of patients with CCRCC. Methods: Samples from two cohorts of CCRCC patients (Asian, 101 cases; U.S., 542 cases) were immunohistochemically doubled-stained for a pericyte marker (α-SMA) and a differentiated vessel marker (CD34), followed by multispectral image capturing and computerized image analyses to quantify the microvessel density (MVD) and pericyte coverage of differentiated vessels. The correlations of PC or MVD with clinicopathological characteristics were analyzed. Univariate and multivariate survival analyses were performed. Results: Uneven distributions of differentiated MVD and PC were found, with higher MVD in the peripheral portion of the tumor and higher PC in the inner portion. There was an inverse correlation between differentiated MVD and PC. Higher PC correlated with more aggressive clinicopathological characteristics of CCRCC in both cohorts, including more advanced T-stage, higher pathological grades, and occurrence of tumor necrosis. The MVD:PC ratio was an independent favorable prognostic factor for overall survival in the Asian cohort and for recurrence-free survival in the U.S. cohort. PC and MVD were also independent prognostic factors, with higher PC or lower MVD predicting a poorer outcome. The combination of PC and MVD could better distinguish the outcome of CCRCC patients. PC combined with differentiated MVD, or MVD:PC ratio provided additional independent prognostic information to the Leibovich risk model, and using that information we generated improved risk models. Conclusions: The distributions of MVD and PC were uneven in CCRCC. Higher PC correlated with more aggressive clinicopathological characteristics. PC was an independent unfavorable prognostic factor. Targeting pericytes should be taken into consideration in anti-angiogenic therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4378. doi:1538-7445.AM2012-4378

Abstract 2372: Capture and molecular characterization of CTC in metastatic breast, prostate, colorectal, and renal cancer

The most important determinant of prognosis and management of cancer is the incidence of metastasis. As a result, circulating tumor cell (CTC) detection and enumeration has been demonstrated to be a useful tool in assessing prognosis and monitoring therapeutic response. Current approaches to CTC detection largely depend on the antibody-mediated magnetic capture of the CTC using antibodies against the epithelial cell adhesion molecule (EpCAM), a feature which can be exploited in only a select few malignancies, and even in these cases, CTC capture is directly impacted by the variable expression of EpCAM. Responding to these issues, we have developed a novel parylene-based microfilter device for the capture, enumeration, and molecular characterization of CTC by exploiting size differences between larger epithelial tumor cells and smaller non-tumor blood cells. Our size-based approach, in contrast to immunoaffinity-based platforms, is ‘antigen expression-agnostic’; allowing analysis of diverse CTC populations and CTC from tumor types lacking target capture antigens. In the present study, the prospective collection of 500 blood samples from patients being treated at the Cleveland Clinic-Taussig Cancer Institute in Cleveland, OH is currently underway: 450 with advanced breast (BC), prostate (PC), and colorectal cancer (CRC) (150 from each disease site), and 50 with advanced renal cell carcinoma (RCC) and melanoma (25 from each disease site). To date, we have analyzed 28 patient blood samples by the microfilter device, of which 26 (92.8%) where positive for CTC (total at primary disease site, % samples positive, range of CTC detected) - BC: 1, 100%, 48; PC: 13, 84.6%, 1 to 144; CRC: 7, 100%, 18 to &gt;500; RCC: 7, 100%, 1-128.* Further analysis demonstrates a number of interesting molecular characteristics on CTC, including heterogeneity in intensity of cytokeratin (CK) expression, differential patterns of CK staining on CTC (filamentous vs granular), and the occurrence of CTC as individual events or in clusters. Further, our data in blood samples from RCC demonstrate an ability to analyze CTC from non-EpCAM expressing tumor types, an area of study where many platforms have limited utility. With the ability to perform multiple, repeated sample analyses to detect recurrent disease early and enable drug response surveillance, we believe our technology has the potential to provide a faster, more efficient alternative to currently available methods for CTC analysis. The molecular characteristics on CTC we have identified herein could have critical biological relevance and implications for predicting aggressiveness of CTC and improving therapeutic monitoring. In ongoing studies, we are investigating the correlation of CTC enumeration, morphology, and clustering, with tumor type and treatment efficacy. *Data to be updated prior to presentation

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2372. doi:1538-7445.AM2012-2372

Abstract 5365: Prolonged survival of patients with advanced renal cancer responding to multi-peptide vaccine IMA901 after single-dose cyclophosphamide

Translational research and the clinical development of therapeutic cancer vaccines requires stronger scientific rationalization. Here we demonstrate how immune response markers as well as biomarkers defining the immune regulatory environment were utilized as guiding tools from discovery to advanced clinical trials of IMA901, a novel therapeutic vaccine for the treatment of renal cell carcinoma (RCC). IMA901 consists of multiple tumor-associated peptides (TUMAPs) confirmed to be naturally presented in human RCC tissue by mass spectrometry, selected using differential transcriptomics and preclinically validated by systematic analysis of immunogenicity with artificial antigen-presenting cells. Two consecutive independent clinical studies in a total of 96 HLA-A*02+ advanced/metastatic RCC patients were conducted. The phase I study revealed that T-cell responses to multiple IMA901 antigens were significantly associated with disease control and negatively associated with the presence of FoxP3+ regulatory T cells (Tregs). The subsequent randomized phase II study demonstrated that pre-treatment with a single low dose of cyclophosphamide (Cy) reduced Treg frequencies and prolonged overall survival (OS) in patients who mounted an immune response to the IMA901 vaccine. Additionally, T-cell responses to multiple IMA901 antigens were again associated with clinical benefit. Furthermore, a comprehensive prognostic and predictive biomarker program was conducted. Among cellular biomarkers, highly significantly elevated levels of myeloid-derived suppressor cells (MDSC), IL-17-/IL-10-secreting T cells and dysfunctional T cells in RCC patients vs. healthy individuals were found. Two MDSC populations (CD14+ HLA-DR- and CD14- CD11b+ CD15+) were significantly negatively associated with survival in vaccinated RCC patients. Interestingly, both MDSC populations were also found to be negatively associated with OS in an independent trial in colorectal cancer patients (N=79) implying a broader role for these MDSC species. Additionally, among over 300 serum biomarkers tested, apolipoprotein A-I (ApoA1) and the chemokine CCL17 were found to be predictive for both immune responses to IMA901 and survival of the RCC patients. The knowledge acquired in these trials was used to design a randomized phase III study. In this ongoing study, IMA901 is combined with the tyrosine kinase inhibitor sunitinib based on the findings that sunitinib downmodulates the two MDSC populations described above. Furthermore, in this phase III study, the relevance of ApoA1/CCL17 will be explored by prospectively defined subgroup analyses.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5365. doi:1538-7445.AM2012-5365

p53-Independent, normal stem cell sparing epigenetic differentiation therapy for myeloid and other malignancies

Cytotoxic chemotherapy for acute myeloid leukemia (AML) usually produces only temporary remissions, at the cost of significant toxicity and risk for death. One fundamental reason for treatment failure is that it is designed to activate apoptosis genes (eg, TP53) that may be unavailable because of mutation or deletion. Unlike deletion of apoptosis genes, genes that mediate cell cycle exit by differentiation are present in myelodysplastic syndrome (MDS) and AML cells but are epigenetically repressed: MDS/AML cells express high levels of key lineage-specifying transcription factors. Mutations in these transcription factors (eg, CEBPA) or their cofactors (eg., RUNX1) affect transactivation function and produce epigenetic repression of late-differentiation genes that antagonize MYC. Importantly, this aberrant epigenetic repression can be redressed clinically by depleting DNA methyltransferase 1 (DNMT1, a central component of the epigenetic network that mediates transcription repression) using the deoxycytidine analogue decitabine at non-cytotoxic concentrations. The DNMT1 depletion is sufficient to trigger upregulation of late-differentiation genes and irreversible cell cycle exit by p53-independent differentiation mechanisms. Fortuitously, the same treatment maintains or increases self-renewal of normal hematopoietic stem cells, which do not express high levels of lineage-specifying transcription factors. The biological rationale for this approach to therapy appears to apply to cancers other than MDS/AML also. Decitabine or 5-azacytidine dose and schedule can be rationalized to emphasize this mechanism of action, as an alternative or complement to conventional apoptosis-based oncotherapy.

Vascular endothelial growth factor-targeted therapies in advanced renal cell carcinoma

Vascular endothelial growth factor (VEGF) is, to date, the key element in the pathogenesis of renal cell carcinoma (RCC). VEGF pathway activation is responsible for the recruitment, migration, and expansion of endothelial cells, with this angiogenesis tumor model being characteristic of RCC. Different strategies have been developed for almost a decade to block the VEGF pathway in this setting. Four different compounds were approved for metastatic RCC (mRCC) in the past 6 years: bevacizumab, sunitinib, sorafenib, and pazopanib. Axitinib and tivozanib are also promising compounds under evaluation. The revolution in the management and prognosis of patients with mRCC is ongoing.

Myeloid-derived suppressor cell accumulation and function in patients with newly diagnosed glioblastoma

To assess the accumulation of myeloid-derived suppressor cells (MDSCs) in the peripheral blood of patients with glioma and to define their heterogeneity and their immunosuppressive function. Peripheral blood mononuclear cells (PBMCs) from healthy control subjects and from patients with newly diagnosed glioma were stimulated with anti-CD3/anti-CD28 and T cells assessed for intracellular expression of interferon (IFN)-γ. Antibody staining of PBMCs from glioma patients and healthy donors (CD33, HLADR, CD15, and CD14) followed by 4-color flow cytometry analysis-defined MDSC levels in the peripheral blood. To assess the role of MDSCs in suppressing T cell IFNγ production, PBMCs were depleted of MDSCs using anti-CD33 and anti-CD15 antibody-coated beads prior to T cell stimulation. Enzyme-linked immunosorbent assays were used to assess plasma arginase activity and the level of granulocyte colony-stimulating factor (G-CSF). Patients with glioblastoma have increased MDSC counts (CD33+HLADR-) in their blood that are composed of neutrophilic (CD15(+); >60%), lineage-negative (CD15(-)CD14(-); 31%), and monocytic (CD14(+); 6%) subsets. After stimulation, T cells from patients with glioblastoma had suppressed IFN-γ production when compared with healthy, age-matched donor T cells. Removal of MDSCs from the PBMCs with anti-CD33/CD15-coated beads significantly restored T cell function. Significant increases in arginase activity and G-CSF levels were observed in plasma specimens obtained from patients with glioblastoma. The accumulation of MDSCs in peripheral blood in patients with glioma likely promotes T cell immune suppression that is observed in this patient population. Increased plasma levels of arginase and G-CSF may relate to MDSC suppressor function and MDSC expansion, respectively, in patients with glioma.