Efficacy and safety of lenvatinib plus pembrolizumab vs sunitinib in the East Asian subset of patients with advanced renal cell carcinoma from the CLEAR trial

In the CLEAR trial, lenvatinib plus pembrolizumab met study endpoints of superiority vs sunitinib in the first-line treatment of patients with advanced renal cell carcinoma. We report the efficacy and safety results of the East Asian subset (ie, patients in Japan and the Republic of Korea) from the CLEAR trial. Of 1069 patients randomly assigned to receive either lenvatinib plus pembrolizumab, lenvatinib plus everolimus or sunitinib, 213 (20.0%) were from East Asia. Baseline characteristics of patients in the East Asian subset were generally comparable with those of the global trial population. In the East Asian subset, progression-free survival was considerably longer with lenvatinib plus pembrolizumab vs sunitinib (median 22.1 vs 11.1 months; HR 0.38; 95% CI: 0.23-0.62). The HR for overall survival comparing lenvatinib plus pembrolizumab vs sunitinib was 0.71; 95% CI: 0.30-1.71. The objective response rate was higher with lenvatinib plus pembrolizumab vs sunitinib (65.3% vs 49.2%; odds ratio 2.14; 95% CI: 1.07-4.28). Dose reductions due to treatment-emergent adverse events (TEAEs) commonly associated with tyrosine kinase inhibitors occurred more frequently than in the global population. Hand-foot syndrome was the most frequent any-grade TEAE with lenvatinib plus pembrolizumab (66.7%) and sunitinib (57.8%), a higher incidence compared to the global population (28.7% and 37.4%, respectively). The most common grade 3 to 5 TEAEs were hypertension with lenvatinib plus pembrolizumab (20%) and decreased platelet count with sunitinib (21.9%). Efficacy and safety for patients in the East Asian subset were generally similar to those of the global population, except as noted.

Efficacy and safety of lenvatinib (LEN) plus pembrolizumab (PEMBRO) versus sunitinib (SUN) in the East Asian subset of patients with advanced renal cell carcinoma (aRCC) from the phase 3 CLEAR trial

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Background: In the phase 3 CLEAR trial that included patients with aRCC, LEN + PEMBRO demonstrated significant improvements in progression-free survival (PFS; hazard ratio [HR] 0.39; 95% CI 0.32, 0.49; P < 0.001), overall survival (OS; HR 0.66; 95% CI 0.49, 0.88; P = 0.005) and objective response rate (ORR; odds ratio 4.35; 95% CI 3.16, 5.97) vs SUN. Here we report the efficacy and safety results of the East Asian population subset of the CLEAR trial. Methods: Patients with aRCC and no prior systemic therapy were randomized (1:1:1) to receive 1 of 3 treatments including LEN 20 mg PO QD + PEMBRO 200 mg IV Q3W and SUN 50 mg PO QD (4 weeks on/2 weeks off). Randomization was stratified by geographic region and MSKCC prognostic groups. This analysis compares the efficacy and safety of LEN + PEMBRO vs SUN in the East Asian subset of the CLEAR trial including patients from Japan and the Republic of Korea. The primary endpoint was PFS; secondary endpoints included OS, ORR and safety. An independent review committee assessed tumors per RECIST v1.1. Median PFS and OS were calculated using the Kaplan-Meier method; HR and 95% CI were estimated by a stratified Cox model. Odds ratios were estimated by a stratified Cochran-Mantel-Haenszel test. Results: Of the 1069 patients randomized, 75 patients in the LEN + PEMBRO group and 65 patients in the SUN group were from East Asia. PFS was improved with LEN + PEMBRO vs SUN (median 22.1 vs 11.1 mo; HR 0.38, 95% CI 0.23, 0.62). Median OS was not reached for both arms; the HR for OS comparing LEN + PEMBRO vs SUN was 0.71, 95% CI 0.30, 1.71. ORR was improved with LEN + PEMBRO vs SUN (65.3% vs 49.2%; odds ratio 2.14, 95% CI 1.07, 4.28). Grade ≥3 treatment emergent adverse events (TEAEs) occurred in 88.0% of patients in the LEN + PEMBRO group and in 79.7% of patients in the SUN group. The incidences and types of TEAEs were generally similar to the overall CLEAR population and were manageable with dose adjustments and appropriate concomitant therapies. Conclusions: Efficacy results for patients in the East Asian subset of the CLEAR trial were consistent with the results of the overall population. The safety profile of LEN + PEMBRO in the East Asian subset was also generally consistent with that of the overall population. Clinical trial information: NCT02811861. [Table: see text]

Abstract 1575: The landscape of tumor intrinsic immune regulators revealed by genome-wide CRISPR immune screen integrated with comprehensive clinical data analysis

Despite approval of immunotherapy for a wide range of cancers, the majority of patients fail to respond to immunotherapy or relapse following initial response which may be attributed to immunosuppression co-opted by tumor cells. However, it is challenging to utilize conventional methods to systematically evaluate the potential of tumor intrinsic factors to act as immune regulators in cancer patients. In this study, we designed an unbiased integrative strategy to leverage the complementary strength of in vitro functional genomic screens and multi-omics clinical data to assess the role of individual tumor-intrinsic factors in regulating T cell tumor infiltration and T cell-mediated tumor killing, the two most important rate-limiting steps of cancer immunotherapy. Initially, a genome-wide CRISPR-Cas9 screening system using paired murine tumors and tumor-reactive T cells was employed to globally screen tumor intrinsic factors modulating the tumor sensitivity to T cell-mediated killing. Then, findings from the screening were integrated with the bioinformatics analysis of clinical datasets to further evaluate the role of each tumor intrinsic factor in governing antitumor immunity. The integrative analysis not only successfully identified several novel tumor intrinsic factors as effectors of immune resistance, but also demonstrated the distinct roles of these factors in controlling immune cell trafficking and tumor sensitivity to T cell-mediated killing. Among these factors, candidates controlling both rate-limiting steps were termed as "Dual immune resistance regulators" and the remaining factors whose expression were not associated with tumor immune infiltration were termed as "Cytotoxicity resistance regulators". By selecting PRMT1 and RIPK1 as representatives of the two groups respectively, we confirmed that genetically depletion of PRMT1 and RIPK1 sensitized tumors to T-cell mediated killing via two independent experimental approaches. Furthermore, inhibiting Prmt1 or Ripk1 tumors sensitizes tumors to cancer immunotherapy, such as anti-PD-1/anti-OX40 treatments (Tumor size (mm2) on day 21 after tumor inoculation: for anti-PD-1 treatment, Ctrl 84.05±23.10, PRMT1 KO 7.30±7.81, RIPK1 KO 2.03±4.96; similar results were also observed from anti-OX40 treatment) and extended the survival of tumor-bearing mice. Moreover, by using a RIPK1-specific inhibitor, GSK2982772, we demonstrated that targeting cytotoxicity resistance regulators could also enhance the antitumor activity of T cell-based cancer immunotherapy, despite limited impact on T cell tumor infiltration. Collectively, our data not only demonstrate the distinct immunoregulatory roles and therapeutic potentials of PRMT1 and RIPK1 in T cell-mediated antitumor activity, but also provides a rich resource of novel targets for rational immuno-oncology combinations.

Citation Format: Jiakai Hou, Yunfei Wang, Leilei Shi, Yuan Chen, Chunyu Xu, Arash Saeedi, Ke Pan, Ritu Bohat, Nicholas A. Egan, Jodi A. McKenzie, Rina M. Mbofung, Leila J. Williams, Zhenghuang Yang, Ming Sun, Xiaofang Liang, Jordi Rodon Ahnert, Navin Varadarajan, Cassian Yee, Yiwen Chen, Patrick Hwu, Weiyi Peng. The landscape of tumor intrinsic immune regulators revealed by genome-wide CRISPR immune screen integrated with comprehensive clinical data analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1575.

Integrating genome-wide CRISPR immune screen with multi-omic clinical data reveals distinct classes of tumor intrinsic immune regulators

BACKGROUND

Despite approval of immunotherapy for a wide range of cancers, the majority of patients fail to respond to immunotherapy or relapse following initial response. These failures may be attributed to immunosuppressive mechanisms co-opted by tumor cells. However, it is challenging to use conventional methods to systematically evaluate the potential of tumor intrinsic factors to act as immune regulators in patients with cancer.

METHODS

To identify immunosuppressive mechanisms in non-responders to cancer immunotherapy in an unbiased manner, we performed genome-wide CRISPR immune screens and integrated our results with multi-omics clinical data to evaluate the role of tumor intrinsic factors in regulating two rate-limiting steps of cancer immunotherapy, namely, T cell tumor infiltration and T cell-mediated tumor killing.

RESULTS

Our studies revealed two distinct types of immune resistance regulators and demonstrated their potential as therapeutic targets to improve the efficacy of immunotherapy. Among them, PRMT1 and RIPK1 were identified as a dual immune resistance regulator and a cytotoxicity resistance regulator, respectively. Although the magnitude varied between different types of immunotherapy, genetically targeting PRMT1 and RIPK1 sensitized tumors to T-cell killing and anti-PD-1/OX40 treatment. Interestingly, a RIPK1-specific inhibitor enhanced the antitumor activity of T cell-based and anti-OX40 therapy, despite limited impact on T cell tumor infiltration.

CONCLUSIONS

Collectively, the data provide a rich resource of novel targets for rational immuno-oncology combinations.

Aurora kinase inhibition sensitizes melanoma cells to T-cell-mediated cytotoxicity

Although immunotherapy has achieved impressive durable clinical responses, many cancers respond only temporarily or not at all to immunotherapy. To find novel, targetable mechanisms of resistance to immunotherapy, patient-derived melanoma cell lines were transduced with 576 open reading frames, or exposed to arrayed libraries of 850 bioactive compounds, prior to co-culture with autologous tumor-infiltrating lymphocytes (TILs). The synergy between the targets and TILs to induce apoptosis, and the mechanisms of inhibiting resistance to TILs were interrogated. Gene expression analyses were performed on tumor samples from patients undergoing immunotherapy for metastatic melanoma. Finally, the effect of inhibiting the top targets on the efficacy of immunotherapy was investigated in multiple preclinical models. Aurora kinase was identified as a mediator of melanoma cell resistance to T-cell-mediated cytotoxicity in both complementary screens. Aurora kinase inhibitors were validated to synergize with T-cell-mediated cytotoxicity in vitro. The Aurora kinase inhibition-mediated sensitivity to T-cell cytotoxicity was shown to be partially driven by p21-mediated induction of cellular senescence. The expression levels of Aurora kinase and related proteins were inversely correlated with immune infiltration, response to immunotherapy and survival in melanoma patients. Aurora kinase inhibition showed variable responses in combination with immunotherapy in vivo, suggesting its activity is modified by other factors in the tumor microenvironment. These data suggest that Aurora kinase inhibition enhances T-cell cytotoxicity in vitro and can potentiate antitumor immunity in vivo in some but not all settings. Further studies are required to determine the mechanism of primary resistance to this therapeutic intervention.

Anti-OX40 Antibody Directly Enhances The Function of Tumor-Reactive CD8+ T Cells and Synergizes with PI3Kβ Inhibition in PTEN Loss Melanoma

PURPOSE

OX40 agonist-based combinations are emerging as a novel avenue to improve the effectiveness of cancer immunotherapy. To better guide its clinical development, we characterized the role of the OX40 pathway in tumor-reactive immune cells. We also evaluated combining OX40 agonists with targeted therapy to combat resistance to cancer immunotherapy.Experimental Design: We utilized patient-derived tumor-infiltrating lymphocytes (TILs) and multiple preclinical models to determine the direct effect of anti-OX40 agonistic antibodies on tumor-reactive CD8⁺ T cells. We also evaluated the antitumor activity of an anti-OX40 antibody plus PI3Kβ inhibition in a transgenic murine melanoma model (Braf mutant, PTEN null), which spontaneously develops immunotherapy-resistant melanomas.

RESULTS

We observed elevated expression of OX40 in tumor-reactive CD8⁺ TILs upon encountering tumors; activation of OX40 signaling enhanced their cytotoxic function. OX40 agonist antibody improved the antitumor activity of CD8⁺ T cells and the generation of tumor-specific T-cell memory in vivo. Furthermore, combining anti-OX40 with GSK2636771, a PI3Kβ-selective inhibitor, delayed tumor growth and extended the survival of mice with PTEN-null melanomas. This combination treatment did not increase the number of TILs, but it instead significantly enhanced proliferation of CD8⁺ TILs and elevated the serum levels of CCL4, CXCL10, and IFNγ, which are mainly produced by memory and/or effector T cells.

CONCLUSIONS

These results highlight a critical role of OX40 activation in potentiating the effector function of tumor-reactive CD8⁺ T cells and suggest further evaluation of OX40 agonist-based combinations in patients with immune-resistant tumors.

The Effect of Topoisomerase I Inhibitors on the Efficacy of T-Cell-Based Cancer Immunotherapy

Background

Immunotherapy has increasingly become a staple in cancer treatment. However, substantial limitations in the durability of response highlight the need for more rational therapeutic combinations. The aim of this study is to investigate how to make tumor cells more sensitive to T-cell-based cancer immunotherapy.

Methods

Two pairs of melanoma patient-derived tumor cell lines and their autologous tumor-infiltrating lymphocytes were utilized in a high-throughput screen of 850 compounds to identify bioactive agents that could be used in combinatorial strategies to improve T-cell-mediated killing of tumor cells. RNAi, overexpression, and gene expression analyses were utilized to identify the mechanism underlying the effect of Topoisomerase I (Top1) inhibitors on T-cell-mediated killing. Using a syngeneic mouse model (n = 5 per group), the antitumor efficacy of the combination of a clinically relevant Top1 inhibitor, liposomal irinotecan (MM-398), with immune checkpoint inhibitors was also assessed. All statistical tests were two-sided.

Results

We found that Top1 inhibitors increased the sensitivity of patient-derived melanoma cell lines (n = 7) to T-cell-mediated cytotoxicity (P < .001, Dunnett’s test). This enhancement is mediated by TP53INP1, whose overexpression increased the susceptibility of melanoma cell lines to T-cell cytotoxicity (2549 cell line: P = .009, unpaired t test), whereas its knockdown impeded T-cell killing of Top1 inhibitor–treated melanoma cells (2549 cell line: P < .001, unpaired t test). In vivo, greater tumor control was achieved with MM-398 in combination with α-PD-L1 or α-PD1 (P < .001, Tukey’s test). Prolonged survival was also observed in tumor-bearing mice treated with MM-398 in combination with α-PD-L1 (P = .002, log-rank test) or α-PD1 (P = .008, log-rank test).

Conclusions

We demonstrated that Top1 inhibitors can improve the antitumor efficacy of cancer immunotherapy, thus providing the basis for developing novel strategies using Top1 inhibitors to augment the efficacy of immunotherapy.

The RNA-binding Protein MEX3B Mediates Resistance to Cancer Immunotherapy by Downregulating HLA-A Expression

Purpose: Cancer immunotherapy has shown promising clinical outcomes in many patients. However, some patients still fail to respond, and new strategies are needed to overcome resistance. The purpose of this study was to identify novel genes and understand the mechanisms that confer resistance to cancer immunotherapy.Experimental Design: To identify genes mediating resistance to T-cell killing, we performed an open reading frame (ORF) screen of a kinome library to study whether overexpression of a gene in patient-derived melanoma cells could inhibit their susceptibility to killing by autologous tumor-infiltrating lymphocytes (TIL).Results: The RNA-binding protein MEX3B was identified as a top candidate that decreased the susceptibility of melanoma cells to killing by TILs. Further analyses of anti-PD-1-treated melanoma patient tumor samples suggested that higher MEX3B expression is associated with resistance to PD-1 blockade. In addition, significantly decreased levels of IFNγ were secreted from TILs incubated with MEX3B-overexpressing tumor cells. Interestingly, this phenotype was rescued upon overexpression of exogenous HLA-A2. Consistent with this, we observed decreased HLA-A expression in MEX3B-overexpressing tumor cells. Finally, luciferase reporter assays and RNA-binding protein immunoprecipitation assays suggest that this is due to MEX3B binding to the 3' untranslated region (UTR) of HLA-A to destabilize the mRNA.Conclusions: MEX3B mediates resistance to cancer immunotherapy by binding to the 3' UTR of HLA-A to destabilize the HLA-A mRNA and thus downregulate HLA-A expression on the surface of tumor cells, thereby making the tumor cells unable to be recognized and killed by T cells. Clin Cancer Res; 24(14); 3366-76. ©2018 AACRSee related commentary by Kalbasi and Ribas, p. 3239.

Increased Tumor Glycolysis Characterizes Immune Resistance to Adoptive T Cell Therapy

Adoptive T cell therapy (ACT) produces durable responses in some cancer patients; however, most tumors are refractory to ACT and the molecular mechanisms underlying resistance are unclear. Using two independent approaches, we identified tumor glycolysis as a pathway associated with immune resistance in melanoma. Glycolysis-related genes were upregulated in melanoma and lung cancer patient samples poorly infiltrated by T cells. Overexpression of glycolysis-related molecules impaired T cell killing of tumor cells, whereas inhibition of glycolysis enhanced T cell-mediated antitumor immunity in vitro and in vivo. Moreover, glycolysis-related gene expression was higher in melanoma tissues from ACT-refractory patients, and tumor cells derived from these patients exhibited higher glycolytic activity. We identified reduced levels of IRF1 and CXCL10 immunostimulatory molecules in highly glycolytic melanoma cells. Our findings demonstrate that tumor glycolysis is associated with the efficacy of ACT and identify the glycolysis pathway as a candidate target for combinatorial therapeutic intervention.

Complementing T-cell Function: An Inhibitory Role of the Complement System in T-cell-Mediated Antitumor Immunity

New data from Wang and colleagues show that complement C3 suppresses the function of CD8(+) tumor-infiltrating T cells by inhibiting IL10 production, and targeting the complement receptors C3aR and C5aR enhances the antitumor activity of immune checkpoint blockade. Their results not only define a new role of complement receptors as T-cell coinhibitory receptors, but also are useful in the development of novel strategies to improve the effectiveness of cancer immunotherapy. Cancer Discov; 6(9); 953-5. ©2016 AACR.See related article by Wang et al., p. 1022.

HSP90 inhibition enhances cancer immunotherapy by upregulating interferon response genes

T-cell-based immunotherapies are promising treatments for cancer patients. Although durable responses can be achieved in some patients, many patients fail to respond to these therapies, underscoring the need for improvement with combination therapies. From a screen of 850 bioactive compounds, we identify HSP90 inhibitors as candidates for combination with immunotherapy. We show that inhibition of HSP90 with ganetespib enhances T-cell-mediated killing of patient-derived human melanoma cells by their autologous T cells in vitro and potentiates responses to anti-CTLA4 and anti-PD1 therapy in vivo. Mechanistic studies reveal that HSP90 inhibition results in upregulation of interferon response genes, which are essential for the enhanced killing of ganetespib treated melanoma cells by T cells. Taken together, these findings provide evidence that HSP90 inhibition can potentiate T-cell-mediated anti-tumor immune responses, and rationale to explore the combination of immunotherapy and HSP90 inhibitors.

Many patients fail to respond to T cell based immunotherapies. Here, the authors, through a high-throughput screening, identify HSP90 inhibitors as a class of preferred drugs for treatment combination with immunotherapy.

Abstract B110: Topoisomerase I inhibitors enhance efficacy of immunotherapy through a p53 regulatory pathway

Cancer immunotherapy has transformed the treatment landscape for a number of cancer patients, with some achieving durable and long lasting clinical benefit. Cancer immunotherapy engages and intensifies the host immune response to attack and kill tumor cells. However, as evidenced by the heterogeneous response to immunotherapy, tumor cells have evolved a host of known and unknown mechanisms to evade, inhibit or supersede the immune response. Consequently, scientists and clinicians are unable to accurately predict which patients will respond, or how well they will respond to cancer immunotherapy.To address this shortfall, we have asked the question of how we can modulate tumor cells in order to make them more amenable to immunotherapy, thereby increasing its efficacy. We approached this question by conducting a high throughput drug screen of 850 compounds, to identify bioactive drugs that can increase T cell mediated killing of tumor cells. The goal here is to develop rational combination treatment strategies involving T cell based cancer immunotherapy that will increase the breadth and depth of the clinical response to cancer immunotherapy. One of three top hits from the screen was Topoisomerase I (Top1) inhibitors including irinotecan, topotecan, and camptothecin. We then utilized multiple patient-derived cell lines in an in vitro cytotoxicity assay to validate that treatment of melanoma tumor cells with a Top1 inhibitor, before incubation with their autologous tumor infiltrating lymphocytes (TILs) results in a synergistic increase in T cell mediated killing of tumor cells.These findings were further corroborated in a pre-clinical mouse model, where we found that tumor-bearing mice treated with a combination of a clinically relevant Top1 inhibitor nal-IRI (nano-liposomal irinotecan) and an anti-PD-L1 antibody, showed enhanced tumor regression compared to mice treated with either single agent (mean tumor volume: combo vs nal-IRI vs α-PDL1 = 40.04 ± 5.66 vs 136.30 ± 28.96 vs 373.04 ± 23.96 mm3 respectively, on day 21 after tumor inoculation, p &lt; 0.0001). Significantly longer survival was also achieved in tumor-bearing mice treated with the combination in comparison to cohorts treated with either single agent. To investigate the molecular changes being mediated by Top1 inhibitors in the tumor cells, we conducted gene expression analysis on Top1 inhibitor-treated tumor cells. One striking gene expression change in Top1 inhibitor-treated tumor cells was an upregulation of a number of genes known to be functionally important for p53 signaling including TP53INP1 (Teap). We then focused on the functional relevance of Teap to the increased T cell mediated killing of Top1 inhibitor-treated melanoma cells. Overexpression of Teap in melanoma cells resulted in increased T cell mediated killing, recapitulating the phenotype observed in Top1 inhibitor-treated melanoma cells. Complementary to this, silencing of Teap via shRNA in melanoma cells, inhibited T cell mediated killing of Top1 inhibitor-treated cells, indicating that the enhancement of T cell mediated killing observed in Top1 inhibitor-treated cells is dependent on the p53 regulatory gene Teap. These results support our goal of developing combinations involving T cell based cancer immunotherapy to improve therapeutic efficacy in cancer patients. We have demonstrated that Top1 inhibitors can be effectively combined with T cell based cancer immunotherapy. The results are also indicative of a role for p53 signaling in regulating response to T cell based immunotherapy. By understanding the molecular mechanisms in the tumor that can dictate response or resistance to immunotherapy, we can develop a more comprehensive picture of the cancer immunity response cycle and develop more effective strategies to combat not only melanoma, but also other tumor types where immunotherapy is not yet applicable.

Citation Format: Jodi A. McKenzie, Rina M. Mbofung, Shruti Malu, Rodabe N. Amaria, Emily L. Ashkin, Seram N. Devi, Weiyi Peng, Leila J. Williams, Richard E. Davis, Jason Roszik, Trang N. Tieu, Timothy Heffernan, Patrick Hwu. Topoisomerase I inhibitors enhance efficacy of immunotherapy through a p53 regulatory pathway [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B110.

Abstract B105: HSP90 inhibitor, ganetespib, enhances responses to cancer immunotherapy through increased expression of interferon response genes

Recently, T cell based immunotherapies have moved to the forefront of cancer immunotherapy with the success of Adoptive T cell therapy (ACT) and Immune checkpoint blockade. ACT, where patients are treated with tumor infiltrating T cells (TILs), conferred a clinical response rate of ∼50%. Treatment with anti-CTLA4 therapy, Ipilimumab, conferred response rates of 10-20%, greatly improving the overall survival of patients with advanced melanoma. Despite the encouraging outcomes, there are relatively low response rates coupled with the delay of weeks to months before tumor shrinkage can be appreciated. Thus, understanding mechanisms of resistance to immune therapies, to improve response rates, shorten time to treatment effect and developing predictive biomarkers of response are vital to the care of melanoma patients. In order to identify possible resistance mechanisms to immunotherapy, a high-throughput in vitro screen with 850 different bio-active compounds (Selleckchem), was designed to search for agents that could either increase or decrease the resistance of melanoma tumor cells to T cell mediated killing. Paired patient derived human melanoma tumor samples and TILs were used to assess which compounds when used to treat the melanoma cell lines can enhance the cytotoxic activity of the TILs against the paired melanoma sample, using a flow cytometry based assay in which active caspase 3 was used as a read out of apoptosis. We identified heat shock protein 90 (HSP90) inhibitors amongst the top compounds that improved T cell mediated cytotoxicity of treated tumor cells. We show that treatment with the HSP90 inhibitor ganetespib (Synta) greatly improves T cell mediated cytotoxicity of human cancer cells lines in vitro. Furthermore, in vivo murine studies using the MC38/gp100 tumor model show that ganestespib in combination with anti-CTLA4, resulted in superior antitumor effect and survival compared to either treatment alone (Average tumor volume at day 21 of treatment: Vehicle 294.3mm3, α-CTLA4 193 mm3, Ganetespib 237.5 mm3 and Ganetespib + α-CTLA4 105.8 mm3, P &lt; 0.0001). Microarray analysis of human cell lines treated with ganetespib in vitro revealed an increase in interferon response genes including IFIT1, IFIT2, IFIT3. We confirmed these findings with quantitative real time PCR and western blot analyses and found IFIT1, IFIT2 and IFIT3 to be consistently upregulated across multiple melanoma cell lines following treatment with ganetespib. We next sought to verify the importance of the IFIT genes in the synergy observed between ganetespib treatment and T cell killing. First, we overexpressed IFIT1, IFIT2 and IFIT3 in human melanoma cell lines to recapitulate the improved sensitivity of the human melanoma cell lines to T cell killing following treatment with ganetespib. We then co-cultured these cells with their autologous T cells and found that overexpressing IFIT1, IFIT2 and IFIT3 mimicked the effects of ganetespib by increasing the sensitivity to T cell killing over the GFP control. On the other hand, silencing IFIT1, IFIT2 and IFIT3 simultaneously, abrogated the synergy between ganetespib and T cell killing. We are further elucidating the role of these genes in lowering the apoptotic threshold of cancer cells and contributing to the synergy of ganetespib and immunotherapy. This will enable the emergence of a new combination therapy of HSP90 inhibitors and anti-CTLA4 for the treatment of melanoma patients that will increase the percentage of patients responding to immunotherapy and achieving long term responses.

Citation Format: Rina M. Mbofung, Jodi A. McKenzie, Shruti Malu, Chengwen Liu, Weiyi Peng, Isere Kuiatse, Leila Williams, Seram Devi, Zhe Wang, Trang Tieu, Tim Heffernan, Richard E. Davis, Rodabe Amaria, Patrick Hwu. HSP90 inhibitor, ganetespib, enhances responses to cancer immunotherapy through increased expression of interferon response genes [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B105.

Abstract 4360: Inhibition of HSP90 enhances T cell-mediated antitumor immune responses through expression of interferon-alpha response Genes

Recently, T cell based immunotherapies have moved to the forefront of cancer immunotherapy with the success of Adoptive T cell therapy (ACT) and Immune checkpoint blockade. ACT, where patients are treated with tumor infiltrating T cells (TILs), conferred a clinical response rate of ∼50%. Treatment with anti-CTLA4 therapy, Ipilimumab, conferred response rates of 10-20%, greatly improving the overall survival of patients with advanced melanoma. Despite the encouraging outcomes, there are relatively low response rates coupled with the delay of weeks to months before tumor shrinkage can be appreciated. Thus, understanding mechanisms of resistance to immune therapies, to improve response rates, shorten time to treatment effect and developing predictive biomarkers of response are vital to the care of melanoma patients. In order to identify possible resistance mechanisms to immunotherapy, a high-throughput in vitro screen with 850 different bio-active compounds (Selleckchem), was designed to search for agents that could either increase or decrease the resistance of melanoma tumor cells to T cell mediated killing. Paired tumor samples and TILs from melanoma patients were used to assess which compounds when used to treat the melanoma cell lines can enhance the cytotoxic activity of the TILs against the paired melanoma sample, using a flow cytometry based assay in which active caspase 3 was used as a read out of apoptosis. We identified heat shock protein 90 (HSP90) inhibitors amongst compounds that improved T cell mediated cytotoxicity. We show that treatment with the HSP90 inhibitor ganetespib (Synta) greatly improves T cell mediated cytotoxicity of both human and murine cancer cells lines in vitro. Furthermore, in vivo murine studies using the MC38/gp100 tumor model show that ganestespib in combination with anti-CTLA4, resulted in superior antitumor effect and survival compared to either treatment alone (Average tumor volume at day 21 of treatment: Vehicle 294.3mm3, α-CTLA4 193 mm3, Ganetespib 237.5 mm3 and Ganetespib + α-CTLA4 105.8 mm3, P &lt; 0.0001). Microarray analysis of human cell lines treated with ganetespib in vitro revealed an increase in interferon alpha (IFN-α) response genes including IFIT1, IFIT2, IFIT3 and IFIH1. Silencing IFIT2 abrogated the synergy observed with ganetespib treatment and T cell mediated killing, suggesting that the IFN-α response pathway plays an important role in this combination therapy. We are further elucidating the role of these genes in the synergy observed. This will enable the emergence of a new combination therapy of HSP90 inhibitors and anti-CTLA4 for the treatment of melanoma patients that will increase the percentage of patients responding to immunotherapy and achieving long term responses.

Citation Format: Rina M. Mbofung, Jodi A. McKenzie, Shruti Malu, Chengwen Liu, Leila Williams, Weiyi Peng, Zhe Wang, Satyendra Tripathi, Trang Tieu, Shuping Zhao, Seram Devi, Isere Kuiatse, Emily Ashkin, Leah Bailey, Jason Roszik, Samir Hanash, Timothy Heffernan, Richard E. Davis, Rodabe N. Amaria, Patrick Hwu. Inhibition of HSP90 enhances T cell-mediated antitumor immune responses through expression of interferon-alpha response Genes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4360.

Abstract 4002: Enhancing the antitumor efficacy of immunotherapy by using the topoisomerase I inhibitor MM398

Melanoma is a highly aggressive form of skin cancer, whose rates of morbidity and mortality are increasing. The development of immunotherapies like anti-PDL1 and anti-CTLA4 antibodies has resulted in fundamental advances in the treatment of some cancers. However, long lasting responses are only observed in a subset of immunotherapy-treated patients. This shortfall highlights the need for a better understanding of the molecular mechanisms that govern tumor response to immunotherapy.

To address this need, autologous patient-derived tumor cell lines and tumor infiltrating lymphocytes (TILs) were utilized in an in vitro high throughput screen, to identify compounds that increase the sensitivity of melanoma cells to T cell mediated cytotoxicity. The screen consisted of an 850 compound library. One group of compounds that was most able to enhance T cell killing of melanoma cells was topoisomerase I (Top1) inhibitors such as topotecan and irinotecan.

Our results indicate that treatment of melanoma cells with a Top1 inhibitor prior to exposure to autologous T cells produced a synergistic increase in tumor cell death, as measured by intracellular staining of activated caspase 3. We have also recapitulated this finding in an in vivo model, where a better anti-tumor effect was observed in tumor bearing mice treated with an antibody against the co-inhibitory molecule PDL1 in combination with MM398 (nanoliposomal irinotecan), than in cohorts treated with either α-PDL1 or Top1 inhibitor alone. These findings suggest synergism between Top1 inhibitors and immune-based therapies in the treatment of melanoma.

Molecular changes elicited by inhibition of Top1 are now being investigated to identify the factors that mediate the effect of Top1 inhibitors on T cell-mediated killing of melanoma. We have identified a p53-driven gene signature in Top1 inhibitor-treated melanoma cell lines and are investigating the functional relevance of Tumor Protein p53 Inducible Nuclear Protein 1 (TP53INP1) in mediating increased T cell killing of Top1 inhibitor-treated melanoma cells. Our results indicate that TP53INP1 is a critical component of this apoptotic response, as overexpression of TP53INP1 in melanoma cells increased their susceptibility to T cell mediated cytotoxicity. Complementary to this observation, we have also found that knockdown of TP53INP1 by shRNA, impedes the sensitivity of Top1 inhibitor-treated melanoma cells to T cell mediated killing.

Understanding how Top1 inhibitors enhance melanoma killing by immunotherapy will allow for the development of predictive biomarkers, and also augment immune-based therapeutic strategies to ensure durable responses in a larger population of melanoma patients. By using melanoma as a model disease system, we can gain valuable insights into the dynamics of cancer immune response that may be applied to other cancers where effective treatment strategies are also lacking.

Citation Format: Jodi A. McKenzie, Rina M. Mbofung, Shruti Malu, Rodabe N. Amaria, Richard E. Davis, Li Zhang, Trang N. Tieu, Tim P. Heffernan, Patrick Hwu. Enhancing the antitumor efficacy of immunotherapy by using the topoisomerase I inhibitor MM398. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4002.

Abstract B152: Increasing the antitumor efficacy of immunotherapy in melanoma by using topoisomerase I inhibitors

Melanoma is a highly aggressive form of skin cancer, whose rates of morbidity and mortality are continuously increasing. The development of immunotherapeutic agents like anti-PDL1 and anti-CTLA4 antibodies has resulted in fundamental advances in the treatment of melanoma. However, long lasting responses are only observed in a small subset of immunotherapy-treated melanoma patients. This shortfall highlights the need for a better understanding of the molecular mechanisms that govern tumor sensitivity or resistance to immunotherapy. To address this need, autologous patient-derived tumor cell lines and tumor infiltrating lymphocytes (TILs) were utilized in an in vitro activated caspase 3-based high-throughput screen, to identify compounds that increase the sensitivity of melanoma cells to T-cell mediated cytotoxicity. The screen consisted of a library of 850 bioactive compounds. One group of compounds that was most able to enhance T-cell killing of melanoma cells was topoisomerase I (Top1) inhibitors including: topotecan, and irinotecan.

Topoisomerases are a family of DNA enzymes, which are involved in unwinding DNA and relieving torsional strain during replication and transcription. Our results indicate that treatment of melanoma tumor cells with a Top1 inhibitor prior to exposure to autologous T cells, produced a synergistic increase in tumor cell death, as measured by intracellular staining of activated caspase 3, and computed using CalcuSyn. We have also recapitulated this finding in an in vivo model, where a better anti-tumor effect was observed in tumor- bearing mice treated with an antibody against the co-inhibitory molecule Programmed Death Ligand 1 (PDL1) in combination with a nanoparticle liposomal formulation of irinotecan, than in cohorts treated with either antibody or drug alone. These findings suggest synergism between Top1 inhibitors and immune-based therapies in the treatment of melanoma.

Genomic and proteomic changes elicited by inhibition of Top1 are now being investigated to identify the molecular factors that mediate the effect of Top1 inhibitors on T cell-mediated killing of melanoma. Our goal is to identify molecular changes mediated by Top1 inhibition in melanoma tumor cells, and/or the tumor microenvironment, that relieves immunosuppression and potentiates the activity of cytotoxic T cell-based immunotherapy.

Understanding how Top1 inhibitors enhance melanoma killing by immunotherapy will allow for the development of predictive biomarkers, and also augment immune-based therapeutic strategies to ensure durable responses in a larger population of melanoma patients. By using melanoma as a model disease system, we can gain valuable insights into the dynamics of cancer immune response that may be applied to other cancers where effective treatment strategies are also lacking.

Citation Format: Jodi A. McKenzie, Rina M. Mbofung, Shruti Malu, Patrick Hwu. Increasing the antitumor efficacy of immunotherapy in melanoma by using topoisomerase I inhibitors. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B152.

Loss of PTEN Promotes Resistance to T Cell-Mediated Immunotherapy

T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors.

SIGNIFICANCE

This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.

Loss of PTEN Promotes Resistance to T Cell-Mediated Immunotherapy

T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors.

SIGNIFICANCE

This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.

Loss of PTEN Promotes Resistance to T Cell-Mediated Immunotherapy

T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors.

SIGNIFICANCE

This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.

Methanogenesis produces strong 13C enrichment in stromatolites of Lagoa Salgada, Brazil: a modern analogue for Palaeo-/Neoproterozoic stromatolites?

Holocene stromatolites characterized by unusually positive inorganic δ(13) CPDB values (i.e. up to +16‰) are present in Lagoa Salgada, a seasonally brackish to hypersaline lagoon near Rio de Janeiro (Brazil). Such positive values cannot be explained by phototrophic fixation of CO2 alone, and they suggest that methanogenesis was a dominating process during the growth of the stromatolites. Indeed, up to 5 mm methane was measured in the porewater. The archaeal membrane lipid archaeol showing δ(13) C values between -15 and 0‰ suggests that archaea are present and producing methane in the modern lagoon sediment. Moreover, (13) C-depleted hopanoids diplopterol and 3β-methylated C32 17β(H),21β(H)-hopanoic acid (both -40‰) are preserved in lagoon sediments and are most likely derived from aerobic methanotrophic bacteria thriving in the methane-enriched water column. Loss of isotopically light methane through the water column would explain the residual (13) C-enriched pool of dissolved inorganic carbon from where the carbonate constituting the stromatolites precipitated. The predominance of methanogenic archaea in the lagoon is most likely a result of sulphate limitation, suppressing the activity of sulphate-reducing bacteria under brackish conditions in a seasonally humid tropical environment. Indeed, sulphate-reduction activity is very low in the modern sediments. In absence of an efficient carbonate-inducing metabolic process, we propose that stromatolite formation in Lagoa Salgada was abiotically induced, while the (13) C-enriched organic and inorganic carbon pools are due to methanogenesis. Unusually, (13) C-enriched stromatolitic deposits also appear in the geological record of prolonged periods in the Palaeo- and Neoproterozoic. Lagoa Salgada represents a possible modern analogue to conditions that may have been widespread in the Proterozoic, at times when low sulphate concentrations in sea water allowed methanogens to prevail over sulphate-reducing bacteria.

Survivin promotion of melanoma metastasis requires upregulation of α5 integrin

Survivin is an apoptotic and mitotic regulator that is overexpressed in melanoma and a poor prognostic marker in patients with metastatic disease. We recently showed that Survivin enhances melanoma cell motility through Akt-dependent upregulation of α5 integrin. However, the functional role of Survivin in melanoma metastasis is not clearly understood. We found that overexpression of Survivin in LOX and YUSAC2 human melanoma cells increased colony formation in soft agar, and this effect was abrogated by knockdown of α5 integrin by RNA interference. We employed melanoma cell xenografts to determine the in vivo effect of Survivin overexpression on melanoma metastasis. Although Survivin overexpression did not affect primary tumor growth of YUSAC2 or LOX subcutaneous tumors, or indices of proliferation or apoptosis, it significantly increased expression of α5 integrin in the primary tumors and formation of metastatic colonies in the lungs. Additionally, Survivin overexpression resulted in enhanced lung colony formation following intravenous (i.v.) injection of tumor cells in vivo and increased adherence to fibronectin-coated plastic in vitro. Importantly, in vivo inhibition of α5 integrin via intraperitoneal injection of an α5β1 integrin-blocking antibody significantly slowed tumor growth and reduced Survivin-enhanced pulmonary metastasis. Knockdown of α5 integrin in cells prior to i.v. injection also blocked Survivin-enhanced lung colony formation. These findings support a direct role for Survivin in melanoma metastasis, which requires α5 integrin and suggest that inhibitors of α5 integrin may be useful in combating this process.

Models of intellectual disability: towards a perspective of (poss)ability

BACKGROUND

The social and medical models of disability configure the relationship between disability and impairment differently. Neither of these models has provided a comprehensive theoretical or practical basis for talking about intellectual disability (ID). Models that emphasise the interactive nature of disability appear to be more promising. This study explores the ways in which models of disability are reflected in disability discourse in an empirical discourse analysis conducted in the Eastern Cape Province of South Africa.

METHODS

Q methodology was used in this study as a discourse analysis tool. Adults with ID, parents of children with ID and professionals who work with people with ID completed a sorting task where they stated the degree to which they agreed or disagreed with statements that are made about people with ID. This exercise resulted in a pattern of responses for each participant, termed a Q sort and these were used as data in a factor analysis using dedicated Q method software. A second order factor analysis was then performed on the resulting factors.

RESULTS

Four discourses were identified: the Social Model/Human Rights Discourse, the Medical Model/Professional Religious Discourse, the Community Model/Community Religious Discourse and the Interactive Discourse. Except for the last one, each of these discourses adopts a model of disability with a static view of impairment as fixed. The Interactive Discourse appears to be related to dynamic, environmental conceptions of disability where competence is built through social interaction.

CONCLUSIONS

A theory of (poss)ability is proposed and some of its concerns are suggested. This perspective views impairment as an interaction between individuals and their environment and postulates that competence is a function of context, rather than a property of the individual.

Role of the apoptotic and mitotic regulator survivin in melanoma

Melanoma is the deadliest form of skin cancer. Melanoma develops in response to genetic and environmental pressures which lead to oncogenic transformation of normal human melanocytes, the pigment-producing cells in the body. The majority of melanoma-associated deaths are due to metastases, highlighting the importance of understanding the molecular mechanisms driving melanoma development and progression. This review focuses on survivin, and its involvement in the melanoma biology. Since its identification in the late 1990s, a vast body of work has been generated, demonstrating the role of survivin in various malignancies. This review discusses the established mitotic and cytoprotective properties of survivin, and its potential role in melanoma development and progression. A newly recognized functional property of survivin is also discussed, namely enhancement of cellular motility, which may underlie its role in promoting melanoma metastasis. Finally, various therapeutic strategies targeting survivin in melanoma are reviewed.

Obstructive sleep apnoea and perioperative complications in bariatric patients

BACKGROUND

The objective of this study was to determine the relationship between perioperative complications and the severity of obstructive sleep apnoea (OSA) in patients undergoing bariatric surgery who had undergone preoperative polysomnography (PSG).

METHODS

The records of 797 patients, age >18 yr, who underwent bariatric operations (442 open and 355 laparoscopic procedures) at Mayo Clinic and were assessed before operation by PSG, were reviewed retrospectively. OSA was quantified using the apnoea-hypopnoea index (AHI) as none (≤ 4), mild (5-15), moderate (16-30), and severe (≥ 31). Pulmonary, surgical, and 'other' complications within the first 30 postoperative days were analysed according to OSA severity. Logistic regression was used to assess the multivariable association of OSA, age, sex, BMI, and surgical approach with postoperative complications.

RESULTS

Most patients with OSA (93%) received perioperative positive airway pressure therapy, and all patients were closely monitored after operation with pulse oximetry on either regular nursing floors or in intensive or intermediate care units. At least one postoperative complication occurred in 259 patients (33%). In a multivariable model, the overall complication rate was increased with open procedures compared with laparoscopic. In addition, increased BMI and age were associated with increased likelihood of pulmonary and other complications. Complication rates were not associated with OSA severity.

CONCLUSIONS

In obese patients evaluated before operation by PSG before bariatric surgery and managed accordingly, the severity of OSA, as assessed by the AHI, was not associated with the rate of perioperative complications. These results cannot determine whether unrecognized and untreated OSA increases risk.

Survivin enhances motility of melanoma cells by supporting Akt activation and {alpha}5 integrin upregulation

Survivin expression in melanoma is inversely correlated with patient survival. Transgenic mice harboring melanocyte-specific overexpression of survivin exhibit increased susceptibility to UV-induced melanoma and metastatic progression. To understand the mechanistic basis for metastatic progression, we investigated the effects of survivin on the motility of human melanocytes and melanoma cells. We found that survivin overexpression enhanced migration on fibronectin and invasion through Matrigel, whereas survivin knockdown under subapoptotic conditions blocked migration and invasion. In melanocytes, survivin overexpression activated the Akt and mitogen-activated protein kinase pathways. Akt phosphorylation was required for survivin-enhanced migration and invasion, whereas Erk phosphorylation was required only for enhanced invasion. In both melanocytes and melanoma cells, survivin overexpression was associated with upregulation of α5 integrin (fibronectin receptor component), the antibody-mediated blockade or RNA interference-mediated knockdown of which blocked survivin-enhanced migration. Knockdown of α5 integrin did not affect Akt activation, but inhibition of Akt phosphorylation prevented α5 integrin upregulation elicited by survivin overexpression. Together, our results showed that survivin enhanced the migration and invasion of melanocytic cells and suggested that survivin may promote melanoma metastasis by supporting Akt-dependent upregulation of α5 integrin.

Mass mortality and its environmental and evolutionary consequences

The latest Mesozoic and earliest Tertiary sediments at Deep Sea Drilling Project site 524 provide an amplified record of environmental and biostratographic changes at the end of Cretaceous. Closely spaced samples, representing time intervals as short as 10(2) or 10(3) years, were analyzed for their bulk carbonate and trace-metal compositions, and for oxygen and carbon isotopic compositions. The data indicate that at the end of Cretaceous, when a high proportion of the ocean's planktic organisms were eliminated, an associated reduction in productivity led to a partial transfer of dissolved carbon dioxide from the oceans to the atmosphere. This resulted in a large increase of the atmospheric carbon dioxide during the next 50,000 years, which is believed to have caused a temperature rise revealed by the oxygen-isotope data. The lowermost Tertiary sediments at site 524 include fossils with Cretaceous affinities, which may include both reworked individuals and some forms that survived for a while after the catastrophe. Our data indicate that many of the Cretaceous pelagic organisms became extinct over a period of a few tens of thousands of years, and do not contradict the scenario of cometary impact as a cause of mass mortality in the oceans, as suggested by an iridium anomaly at the Cretaceous-Tertiary boundary.

Retina-specific LDH isozyme in blueback herring, Alosa aestivalis (Mitchell), and alewife, Alosa pseudoharengus (Wilson)

The retina of 390 Alosa aestivalis and 410 Alosa pseudoharengus have been examined by means of starch-gel electrophoresis. The retina-specific E4 isozyme has been found to occur in all the fish examined. This study demonstrates for the first time that the E4 isozyme occurs in A. aestivalis. Because the E4 isozyme is not polymorphic and has an identical mobility in A. pseudoharengus and in A. aestivalis it is neither suitable for use as a species identification characteristic nor a population marker.

Positional cloning of a cyromazine resistance gene in Drosophila melanogaster

Cyromazine is an effective insecticide used to control dipteran insects. Its precise mode of action is yet to be determined, although it has been suggested that it interferes with the hormone system, sclerotization of the cuticle, or nucleic acid metabolism. To understand the way in which cyromazine acts, we have positionally cloned a cyromazine resistance gene from Drosophila melanogaster. Six cyromazine resistance alleles had previously been generated by ethyl methanasulphonate treatment. Two of these failed to complement each other and here we identify them as having independent non-sense mutations in CG32743, which is an ortholog of Smg1 of worms and mammals and encodes a phosphatidylinositol kinase-like kinase (PIKK). RNAi experiments confirm that cyromazine resistance can be achieved by knocking down CG32743. These are the first cyromazine resistant mutations identified at the nucleotide level. In mammals Smg1 phosphorylates P53 in response to DNA damage. This finding supports the hypothesis that cyromazine interferes with nucleic acid metabolism.

Molecular systematics and biogeography of the bent-wing bat complex Miniopterus schreibersii (Kuhl, 1817) (Chiroptera: Vespertilionidae)

The complete mitochondrial ND2 gene (1037 bp) was sequenced to examine relationships within the bent-wing bat complex, Miniopterus schreibersii (Family Vespertilionidae). It was found that M. schreibersii is a paraphyletic assemblage comprising several species. Two major lineages were identified, one of which was restricted to the Palearctic-Ethiopian regions and the other to the Oriental-Australasian regions. This pattern of differentiation was mirrored by the genus as a whole. Speciation and differentiation within the genus Miniopterus appears to have a hierarchical geographical pattern. The earliest divergence corresponds to the Ethiopian-Palearctic and the Oriental-Australasian biogeographical zones. This early divergence is then followed by radiations within each of the Ethiopian, Oriental and Australasian regions. The study also revealed that the number of species currently recognized (11 or 13) is a gross underestimate of the number of actual species. The emerging picture is one of a relatively speciose genus with most species having relatively restricted distributions; few, if any, occur in more than one biogeographical region.

The genetic, molecular and phenotypic consequences of selection for insecticide resistance

Studies of insecticide resistance allow theories of the adaptive process to be tested where the selective agent, the insecticide, is unambiguously defined. Thus, the consequences of selection of phenotypic variation can be investigated in genetic, biochemical, molecular, population biological and, most recently, developmental contexts. Are the options limited biochemically and molecularly? Is the genetic mechanism monogenic or polygenic, general or population/species specific? Are fitness and developmental patterns associated? These questions of general evolutionary significance can be considered with experimental approaches to determine how insecticide resistance evolves.

Oligonucleotides with bistranded abasic sites interfere with substrate binding and catalysis by human apurinic/apyrimidinic endonuclease

Apurinic/apyrimidinic endonuclease (AP endo) is a key enzyme in oxidative damage DNA repair. The enzyme, which repairs abasic sites, makes a single nick 5' to the phosphodeoxyribose, leaving a free 3'-hydroxyl. We recently described single turnover kinetics for human recombinant AP endo acting on an oligonucleotide with a single abasic site. We hypothesized that the structural changes induced by the presence of a second abasic site might provide insight into how AP endo recognizes the first abasic site. Here we performed steady state and single turnover experiments using bistranded abasic site substrates, with the second site located on the complementary strand to the one being followed and either opposite to the first or displaced in the 5' direction. All sites on the complementary strand were within half a helical turn of the first. The catalytic efficiency was reduced 80 to 96% and the Kd for substrate binding and dissociation was elevated 40- to 125-fold. The smaller changes occurred when the second site was opposite the first site or displaced by four nucleotides. In addition, if the second abasic site was directly across the helix or displaced by 1 or 3 nucleotides from the first abasic site, cleavage of the first abasic site was subject to apparent substrate inhibition, which did not occur if the second abasic site was displaced by four nucleotides from the first. While a substrate containing a nick without a phosphodeoxyribose on the contralateral strand abasic site did not inhibit nicking of the first strand, a substrate with a nicked abasic site on the contralateral strand was an even stronger inhibitor of enzyme action than an oligonucleotide containing the corresponding abasic site on each strand. Consequently, the inhibitory effect of the second abasic site is probably the result of prior cleavage of the abasic site on the contralateral strand with resulting distortions to the DNA helix that interfere with enzyme binding and/or cleavage.

A method for the extraction of ammonium from freshwaters for nitrogen isotope analysis

The measurement of delta15N values of inorganic nitrogen species is an important analytical tool to trace nitrogen species in order to understand nitrogen cycling in aquatic systems. Nitrogen isotope analysis of freshwater ammonium has, however, been hindered by the lack of a simple and reliable technique to measure delta15N values at natural abundance levels. We present a simple and rapid method to concentrate ammonium from freshwater samples for on-line N-isotope ratio determination. Ammonium is collected by adsorption on N-free cation exchange resins. The dried N-loaded exchange resin is then directly combusted to produce N2 gas for subsequent delta15N analysis. The method was evaluated with simulated freshwater solutions containing varying amounts of standard NH4+-N (delta15N = 2.1 per thousand) and potentially interfering inorganic and organic compounds. In general, the cation exchange resin method gives accurate and reproducible delta15N values (sigma1 < 0.3 per thousand; n = 10). Because of adsorption interference, high concentrations of cations in solution may cause ammonium loss but do not result in measurable isotope fractionation. Replicate extractions of the ammonium standard added to water collected from four Swiss lakes demonstrate the good performance of this method when applied to low ionic strength natural water samples with modest concentrations of dissolved organic nitrogen.

Fluctuating asymmetry for specific bristle characters in notch mutants of Drosophila melanogaster

Asymmetry has been used as a measure of developmental stability for bilaterally symmetrical organisms. Most studies have failed to partition the genetic and environmental contributions to the asymmetry phenotype due to the limitations of the systems used or the shortcomings in experimental design. The Notch mutants of Drosophila melanogaster were used to study the genetic contribution to asymmetry for six different bristle characters. Asymmetry response was character specific for the mutants examined. For Nspl, N(Co), N264-47, Ax71d, Ax9B2, AxE2, 1(1)N(B) and nd2 significant asymmetry responses, relative to wildtype Canton-S, were observed for some characters. N60g11 and nd1 did not exhibit significant asymmetry for any of the characters examined. All of the mutants except N60g11 and nd1 showed thoracic bristle asymmetry. However, when asymmetry scores were pooled over the five bristle characters which individually exhibited fluctuating asymmetry, no significant differences were found between any genotypes. Therefore pooling asymmetry values across characters obscures the significant character specific asymmetry values observed. Thus caution is necessary when using the asymmetry phenotype of specific characters to draw organism wide conclusions about developmental stability.

Biogeochemistry. Sulfate reducers--dominant players in a low-oxygen world?

Sulfate reducing bacteria can adapt to extreme physical and chemical conditions and play an important role in global geochemical cycles, but their role in the formation of ore deposits has remained controversial. Strong support for such a role is provided by Labrenz et al., who have discovered sulfate-reducing bacteria that can tolerate low levels of oxygen and can precipitate zinc sulfide minerals. The results may have implications for bioremediation and may provide clues to processes that may have been more widespread in the geologic past.

Wings and bristles: character specificity of the asymmetry phenotype in insecticide-resistant strains of Lucilia cuprina

We investigated the hypothesis that observed higher levels of asymmetry displayed by insecticide-resistance genotypes of Lucilia cuprina are restricted to bristle characters, due to the action of resistance genes in bristle cell development, rather than through the disruption of genomic coadaptation. We compared the level of asymmetry of three bristle characters and three wing characters in non-modified and modified-resistance genotypes. Consistent with previous studies, resistance genotypes displayed greater levels of bristle asymmetry than either susceptible or modified genotypes. However, there were no differences among genotypes for any of the wing characters. To confirm that this result is attributable to the action of the resistance and modifier genes themselves, we also examined the responses of both bristle and wing characters to the more general developmental stress of extreme temperature. Sub-optimal temperature was shown to increase both bristle and wing asymmetry, suggesting that there are no underlying differences between the two character types which could, of themselves, explain the differential response observed in the resistance genotypes.

Evaluation of the cleaning and disinfection efficacy of the DEKO-190; award-based automated washer/disinfector

The DEKO-190 Washer-Disinfector combines both automatic washing and thermal disinfection functions and is designed for the decontamination of ward utensils (such as bedpans and urine bottles) and instruments used in minor surgery prior to sterilization. We undertook a microbiological evaluation of the disinfection efficacy of the machine, using its short wash plus disinfection programme and sealed suspensions of test organisms placed at various points within the instrument. Suspensions of Enterococcus faecalis and Poliovirus were totally inactivated, the counts of aerobic organisms within a stool specimen being reduced by a factor of 10(4)whilst spores of Clostridium perfringens were unaffected. The cleaning efficacy of the DEKO-190 was also evaluated under clinical conditions by visual inspection and was found to be satisfactory. Ward-based combined washer-disinfection machines, such as the DEKO-190, have the potential to improve the efficacy of cleaning protocols within healthcare institutions.

A genetic analysis of cyromazine resistance in Drosophila melanogaster (Diptera: Drosophilidae)

Flies resistant to the insect growth regulator cyromazine were selected in the F1 generation from a cyromazine-susceptible strain of Drosophila melanogaster (Meigen) treated with ethyl methanesulfonate. Four resistant strains were isolated by screening with cyromazine at a concentration > LC100 of susceptibles. In each strain, resistance is conferred by a single gene mutation. Cyromazine resistance in two of the mutants (rst(1a)cyr1 and rst(1a)cyr2) localizes to map position 17 of the X chromosome. Evidence is presented that these mutations are alleles of the gene rst(1a)cyr. Cyromazine resistance in another of the mutants (Rst(1b)Cyr) is also X-linked, and localizes to map position 49 of the X chromosome. The location of the gene conferring cyromazine resistance in the other mutant (Rst(2b)Cyr) is map position 66 of chromosome II. This is possibly an allele of a previously characterized cyromazine resistance gene, Rst(2)Cyr. Dosage-mortality analyses demonstrate a low level of cyromazine resistance is conferred in all strains.

Dieldrin resistance in Lucilia cuprina (the australian sheep blowfly): chance, selection and response

Discrete-generation population cages of Lucilia cuprina were initiated with dieldrin-resistant allele (Rdl ) frequencies of 1 or 5% and maintained for 17 generations on media with concentrations of dieldrin in the range 0-0.006% (w/v). The probability of the initial establishment of the Rdl allele in a population was consistently greater at the 5% frequency and dependent on the concentration of dieldrin in the medium for both starting frequencies. Once the resistant allele was established responses to selection were concentration-dependent. It was concluded that in the absence of dieldrin the susceptible allele was selectively favoured, at 0. 00005% (w/v) concentration selection and random genetic drift influenced changes in allele frequency and at concentrations above this the Rdl allele was at a selective advantage. Fixation of Rdl occurred at the higher concentrations. The influence of random genetic drift and selection on the genetic response during the evolution of insecticide resistance is discussed.

The character or the variation: the genetic analysis of the insecticide-resistance phenotype

In this critique it is argued that the genetic basis of the evolution of resistance is dependent on how the phenotypic, and underlying genotypic, variation is channelled during a selective response. A polygenic response is preferentially favoured if selection acts within the phenotypic distribution of susceptibles; a monogenic response is predicted if selection screens rare mutations with phenotypes outside that susceptible distribution. The relevance of this model to the method of genetic analysis, the prediction of resistance mechanisms to novel insecticides, the generation of resistant beneficial insects and the development of the most effective resistance and integrated pest management programmes is discussed.

Risk-assessment scores, prevention strategies, and the incidence of pressure ulcers among the elderly in four Canadian health-care facilities

The accurate prediction of pressure ulcer (PU) development among hospitalized elderly patients is a complex endeavour. A prospective, longitudinal, cohort study of 330 patients over age 65 in 2 Canadian tertiary-care teaching hospitals and 2 long-term-care facilities examined the association between risk-assessment scores, prevention strategies, and PU incidence. The overall PU incidence rate was 9.7%, with half of the subjects who developed a PU doing so in the first week of hospitalization. The incidence rate for "at risk" patients (10.1%) was similar to the rate for "not at risk" patients (9.3%). The number of prevention strategies used was related to risk-assessment scores and to PU development. Paradoxically, the incidence rate increased with the number of prevention strategies employed. The total risk-assessment score that appeared to have the best balance of sensitivity (69%) and specificity (55%) was 19. Four of the 6 risk-assessment subscales were associated with PU development. Logistic regression modelling confirmed the univariate results that the number of prevention strategies used was the best single predictor of PU development. The data confirm that predicting PU development for individual patients is difficult at best. Results suggest that use of a risk-assessment scale alone is not sufficient to accurately predict PU development. The clinical judgement and experience of nurses are required in providing supplementary information to standard measurement instruments.

Predicting insecticide resistance: mutagenesis, selection and response

Strategies to manage resistance to a particular insecticide have usually been devised after resistance has evolved. If it were possible to predict likely resistance mechanisms to novel insecticides before they evolved in the field, it might be feasible to have programmes that manage susceptibility. With this approach in mind, single-gene variants of the Australian sheep blowfly, Lucilia cuprina, resistant to dieldrin, diazinon and malathion, were selected in the laboratory after mutagenesis of susceptible strains. The genetic and molecular bases of resistance in these variants were identical to those that had previously evolved in natural populations. Given this predictive capacity for known resistances, the approach was extended to anticipate possible mechanisms of resistance to cyromazine, an insecticide to which L. cuprina populations remain susceptible after almost 20 years of exposure. Analysis of the laboratory-generated resistant variants provides an explanation for this observation. The variants show low levels of resistance and a selective advantage over susceptibles for only a limited concentration range. These results are discussed in the context of the choice of insecticides for control purposes and of delivery strategies to minimize the evolution of resistance.

Molecular characterization of the Notch homologue from the Australian sheep blowfly, Lucilia cuprina

The Drosophila melanogaster Notch gene product as a receptor of intercellular signals and is central to cell fate specification. The Scalloped wings (Scl) gene is the homologue of Notch in the Australian sheep blowfly, Lucilia cuprina. An allele of Scl is thought to be involved in the modification of Darwinian fitness and bristle asymmetry in flies resistant to organophosphorous chemicals (OPs). As a first step towards the testing of this hypothesis we cloned and sequenced Scl. A full-length cDNA segment representing the mRNA of Scl is 8503 bp and encodes a protein of 2653 amino acids, which shares 73.6% identity with Notch. All functional motifs including EGF-like repeats, LNR repeats, cdc 10/ankyrin repeats, opa and PEST elements are present in the same order as in Notch and the sequence identities peak in these motifs. With respect to genomic structure, intron/exon boundaries are conserved but, in most cases, the Scl introns are larger. Sequence analysis of the upstream genomic region reveals that the gene has a TATA-less promoter. Consistent with a central role in embryogenesis and imaginal development, high levels of Scl expression were detected in the early embryonic and pupal stages.

Genotypically dependent effects of cyromazine on reproduction and offspring development in the Australian Lucilia cuprina (Diptera: Calliphoridae)

The effects of cyromazine on egg production and subsequent egg-to-adult survival were examined on susceptible, heterozygous, and homozygous cyromazine-resistant genotypes of the Australian sheep blowfly Lucilia cuprina (Wiedemann) by administering to adults 10 ppm of cyromazine in drinking water. Cyromazine reduced egg production, hatch, and subsequent larval survival in susceptible genotypes by acting at the embryonic stage of development. Resistance negated these effects dominantly for egg production and egg hatch and in a partially dominant manner for egg-to-adult survivorship.

Stress and asymmetry during arrested development of the Australian sheep blowfly

The dieldrin and diazinon resistance systems of the Australian sheep blowfly (Lucilia cuprina) have been used previously to relate stress, departures from bilateral symmetry, developmental stability and relative fitness. These systems are now used to consider stress and asymmetry in a developmental context. Larval to adult development is shown to be significantly impaired after arrested development at 8 degrees C, however the asymmetry score of adults of a given genotype is similar after arrested or continuous development. Selection against dieldrin-resistant and unmodified diazinon-resistant genotypes occurs during arrested development because greater proportions of these genotypes pupae at 8 degrees C than do susceptible or modified diazinon-resistant genotypes. Pre-pupae of all genotypes complete development equally successfully when transferred from 8 degrees C to 27 degrees C. Adults fail to emerge when pupae formed at 8 degrees C undergo this temperature transition. Temperature-shift experiments show the asymmetry score is determined between pre-pupal and pupal stages of the life cycle. This stage occurs at 27 degrees C in arrested and continuously developing cultures providing an explanation for the independence of stress, selective mortality during developmental arrest and asymmetry score. The results emphasize the need for genetic, environmental and developmental data before an asymmetry phenotype can be directly related to developmental stability and relative fitness.

Fatal association between dieldrin-resistant and susceptible Australian sheep blowflies,Lucilia cuprina

A novel phenomenon of interactions between genotypes of the dieldrin-resistance (Rdl) locus of the Australian sheep blowfly (Lucilia cuprina) is described. Susceptible adult flies exposed to dieldrin-resistant (Rdl/Rdl or Rdl/S) adults, raised from larvae grown on media containing sublethal concentrations of dieldrin, display mortality related to the concentration on which the resistant flies developed. The resistant flies excrete quantities of dieldrin that are toxic to susceptible flies. These observations provide an additional mechanism to those previously identified for the rapid evolution of resistance to dieldrin by L. cuprina.

Asymmetry--where evolutionary and developmental genetics meet

The mechanisms responsible for the fine tuning of development, where the wildtype phenotype is reproduced with high fidelity, are not well understood. The difficulty in approaching this problem is the identification of mutant phenotypes indicative of a defect in these fine-tuning control mechanisms. Evolutionary biologists have used asymmetry as a measure of developmental homeostasis. The rationale for this was that, since the same genome controls the development of the left and right sides of a bilaterally symmetrical organism, departures from symmetry can be used to measure genetic or environmental perturbations. This paper examines the relationship between asymmetry and resistance to organophosphorous insecticides in the Australian sheep blowfly, Lucilia cuprina. A resistance gene, Rop-1, which encodes a carboxylesterase enzyme, also confers a significant increase in asymmetry. Continued exposure of resistant populations to insecticide has selected a dominant suppressor of the asymmetry phenotype. Genetic evidence indicates that the modifier is the L. cuprina Notch homologue.

Environmental and genetic effects on the asymmetry phenotype: Diazinon resistance in the Australian sheep blowfly, Lucilia cuprina

The asymmetry phenotype of diazinon-resistant flies lacking a fitness/asymmetry Modifier (+/+; R/-) was dominant and independent of developmental temperature, larval density and diazinon concentration. Asymmetry score, pooled over three bristle characters, was approximately 50% greater for these phenotypes than for those of modified genotypes (M/+; +/+) and unmodified susceptibles (+/+; S/S) reared under standard laboratory conditions. Modified and susceptible phenotypes showed increased asymmetry score for temperatures and larval densities above and below standard rearing conditions; a positive correlation was observed between diazinon concentration and asymmetry score. Single and multiple environmental stresses resulted in similar scores that approached, but never exceeded, those of unmodified resistant phenotypes. Irrespective of the developmental conditions anti-symmetry and fluctuating asymmetry were typically observed for each bristle character of unmodified resistant and the modified and susceptible phenotypes, respectively. Thus while similar asymmetry scores could arise from genetic or environmental effects, asymmetry pattern was genetically based. Population cage analyses at different temperatures and larval densities showed a negative association between mean asymmetry and relative fitness.

Scalloped wings is the Lucilia cuprina Notch homologue and a candidate for the modifier of fitness and asymmetry of diazinon resistance

The Scalloped wings (Scl) gene of the Australian sheep blowfly, Lucilia cuprina, is shown to be the homologue of the Drosophila melanogaster Notch gene by comparison at the DNA sequence and genetic levels. A L. cuprina genomic fragment, which shows strong identity with the Notch (N) gene at the molecular level, hybridizes to the location of the Scl gene on polytene chromosomes. The two genes are functionally homologous; the dominant and recessive Notch-like phenotypes produced by mutations in the Scl gene allow these alleles to be classed as N-like or Abruptex-like. The Scl gene is under investigation as a candidate for the fitness and asymmetry Modifier (M) of diazinon resistance. We show that M affects the penetrance of wing and bristle phenotypes associated with two Scl alleles in a manner consistent with the M being an allele of Scl. In addition, we report a phenotypic interaction between the diazinon-resistance mutation, Rop-1, and the same alleles of Scl. We propose that the product of Rop-1, an esterase, may be involved in cell adhesion in developmental processes involving the Scl gene product.

Predicting resistance and managing susceptibility to cyromazine in the Australian sheep blowfly Lucilia cuprina

Four cyromazine-resistant variants of Lucilia cuprina were selected after ethyl methanesulfonate mutagenesis and screening above the concentration of cyromazine lethal to susceptibles. Resistance is controlled by a single gene in each variant. Two resistance loci have been identified, one (Cyr 4) closely linked to the marker 'reduced eyes' on chromosome IV, the other (Cyr 5) closely linked to the 'stubby bristles' marker on chromosome V. Concentration-mortality line analysis shows resistance ratios are low (1.5-3x). One variant [Cyr 4(2)] is viable as a homozygote, the others are lethal [Cyr 4(1)] or, at best subvital [Cyr 5(1) and Cyr 5(2)]. Competition experiments between resistant heterozygotes and susceptibles show that resistance to cyromazine is selected for over a limited range of concentrations. The capacity of laboratory studies to predict likely resistance mechanisms before they evolve in the field is discussed. The use of genetic, toxicological and relative fitness data arising from these studies to devise the most effective strategies of insecticide usage while minimising the evolution of resistance is emphasised.