Characterization of an Anti-CD70 Half-Life Extended Bispecific T Cell Engager (HLE-BiTE) and Associated On-Target Toxicity in Cynomolgus Monkeys

Bispecific T cell Engager (BiTE®) molecules have great potential to treat cancer. Nevertheless, dependent on the targeted tumor antigen, the mechanism of action that drives efficacy may also contribute to on-target/off-tumor toxicities. In this study we characterize an anti-CD70 half-life extended BiTE molecule (termed N6P) which targets CD70, a TNF family protein detected in several cancers. Firstly, the therapeutic potential of N6P was demonstrated using in vitro cytotoxicity assays and an orthotopic xenograft mouse study resulting in potent killing of CD70+ cancer cells. Next, in vitro characterization demonstrated specificity for CD70 and equipotent activity against human and cynomolgus monkey CD70+ cells. To understand the potential for on-target toxicity, a tissue expression analysis was performed and indicated CD70 is primarily restricted to lymphocytes in normal healthy tissues and cells. Therefore, no on-target toxicity was expected to be associated with N6P. However, in a repeat-dose toxicology study using cynomolgus monkeys, adverse N6P-mediated inflammation was identified in multiple tissues frequently involving the mesothelium and epithelium. Follow-up immunohistochemistry analysis revealed CD70 expression in mesothelial and epithelial cells in some tissues with N6P-mediated injury, but not in control tissues or those without injury. Collectively the data indicates that for some target antigens such as CD70, BiTE molecules may exhibit activity in tissues with very low antigen expression or the antigen may be upregulated under stress enabling molecule activity. This work illustrates how a thorough understanding of expression and upregulation is needed to fully address putative liabilities associated with on-target/off-tumor activity of CD3 bispecific molecules.

Abstract 1586: Oncolytic virus HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 promotes systemic anti-tumor responses and cooperates with immuno-modulatory agents in multiple mouse syngeneic tumor models

Oncolytic virotherapy is an emerging treatment modality that may hold promise as a therapeutic option for cancer patients who do not respond to checkpoint inhibitors. Oncolytic viruses preferentially replicate in tumor cells, offer the ability to express transgenes and have been shown to modify the local and distant tumor microenvironments from immunosuppressive to immunostimulatory. We generated HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12, an oncolytic virus based on a modified herpes simplex virus type 1 (HSV-1) designed to selectively replicate in tumors and produce murine FMS-like tyrosine kinase 3 ligand (mFLT3L) to enhance dendritic cell expansion and T cell priming, and murine interleukin-12 (mIL12) to potentiate type I helper and cytotoxic T cell responses. We confirmed the expression and bioactivity of mFLT3L and mIL12 in vitro and evaluated the efficacy of HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 alone and in combination with anti-PD-1 or anti-4-1BB treatment in multiple syngeneic mouse tumor models. Bilateral tumor models were used and only one tumor was treated via intratumoral injection with HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12. Anti-tumor responses were evaluated in the injected tumor (local response), the uninjected tumor (abscopal) and via splenic immune profiling (systemic). HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 treatment alone led to tumor growth inhibition in both treated and contralateral tumors, and a significant increase in overall survival in the A20, Neuro2a and MC38 models. HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 in combination with anti-PD-1 blocking antibody further improved tumor growth inhibition in both treated and contralateral tumors in the MC38 syngeneic model, and significantly increased median overall survival compared to either agent as a monotherapy. In addition, HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 in combination with an agonistic antibody targeting 4-1BB significantly increased overall survival compared to either agent as a monotherapy in the MC38 model. To understand antigen-specific anti-tumor T cell responses, MC38 tumor antigen epitopes were identified by combining exome sequencing and MHC/HLA-binding prediction algorithms. Antigen-specific T cell responses were measured in an IFN-γ ELISPOT assay using splenocytes from treated mice. HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 induced and/or enhanced systemic T cell responses directed against both tumor neoantigens and tumor-associated antigens. Together, these data reveal that treatment with HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 can cause direct tumor lysis and induce an adaptive, systemic T cell-mediated anti-tumor immune response that can be further enhanced by concurrent PD-1 blockade or 4-1BB agonism in multiple syngeneic mouse tumor models.

Citation Format: Keegan Cooke, Walter H. Meisen, Petia Mitchell, Juan Estrada, Jinghui Zhan, Jessica Orf, Peng Li, Christina de Zafra, Jing Qing, Jason DeVoss. Oncolytic virus HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 promotes systemic anti-tumor responses and cooperates with immuno-modulatory agents in multiple mouse syngeneic tumor models [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 1586.

AMG 757, a Half-Life Extended, DLL3-Targeted Bispecific T-Cell Engager, Shows High Potency and Sensitivity in Preclinical Models of Small-Cell Lung Cancer

PURPOSE

Small-cell lung cancer (SCLC) is an aggressive neuroendocrine tumor with a high relapse rate, limited therapeutic options, and poor prognosis. We investigated the antitumor activity of AMG 757, a half-life extended bispecific T-cell engager molecule targeting delta-like ligand 3 (DLL3)-a target that is selectively expressed in SCLC tumors, but with minimal normal tissue expression.

EXPERIMENTAL DESIGN

AMG 757 efficacy was evaluated in SCLC cell lines and in orthotopic and patient-derived xenograft (PDX) mouse SCLC models. Following AMG 757 administration, changes in tumor volume, pharmacodynamic changes in tumor-infiltrating T cells (TILs), and the spatial relationship between the appearance of TILs and tumor histology were examined. Tolerability was assessed in nonhuman primates (NHPs).

RESULTS

AMG 757 showed potent and specific killing of even those SCLC cell lines with very low DLL3 expression (<1,000 molecules per cell). AMG 757 effectively engaged systemically administered human T cells, induced T-cell activation, and redirected T cells to lyse tumor cells to promote significant tumor regression and complete responses in PDX models of SCLC and in orthotopic models of established primary lung SCLC and metastatic liver lesions. AMG 757 was well tolerated with no AMG 757-related adverse findings up to the highest tested dose (4.5 mg/kg weekly) in NHP. AMG 757 exhibits an extended half-life in NHP, which is projected to enable intermittent administration in patients.

CONCLUSIONS

AMG 757 has a compelling safety and efficacy profile in preclinical studies making it a viable option for targeting DLL3-expressing SCLC tumors in the clinical setting.

Abstract 2219: OnxoVEXmGM-CSF promotes systemic response to PD-L1 /PD-1 blockade in multiple mouse syngeneic tumor models

Inhibition of the immune-checkpoint axis that involves PD-L1/PD-1 has improved responses and outcomes for certain cancer patients, but there remains unmet need as only a fraction of patients respond to these therapies. Talimogene laherparepvec (T-VEC) is an FDA-approved, first-in-class oncolytic immunotherapy based on a modified herpes simplex virus type 1 (HSV-1) designed to selectively replicate in tumors and produce granulocyte-macrophage stimulating factor (GM-CSF) to enhance a tumor-antigen specific adaptive immune response. Intratumoral treatment with T-VEC has been shown to promote an inflammatory tumor microenvironment both preclinically and clinically. Combining T-VEC with immune checkpoint inhibitors is of high interest to potentially broaden and deepen the clinical responses in checkpoint-resistant tumors. In the current study, we evaluated the efficacy of OncoVEXmGM-CSF (an HSV modified like T-VEC, except that it produces murine GM-CSF) in combination with anti-PD-1/PD-L1 treatment in multiple syngeneic mouse tumor models. Bilateral tumor models were used, where only one tumor was treated with OncoVEXmGM-CSF (representing the local oncolytic effect), allowing the evaluation of systemic abscopal effect in the uninjected contralateral tumors. OncoVEXmGM-CSF in combination with anti-PD-L1/PD-1 enhanced tumor growth inhibition in both treated and contralateral tumors in the A20 and MC38 syngeneic models and overcame anti-PD-L1 resistance in the CT26 model. The combination treatment also led to a significant increase in median overall survival compared to either agent as a monotherapy. In addition, tumor antigen epitopes were identified by combining exome sequencing and MHC/HLA-binding prediction algorithms. Antigen-specific T cell response was measured in an IFN-γ ELISPOT assay using splenocytes from treated mice. OncoVEXmGM-CSF induced and /or enhanced systemic T cell responses directed against both tumor neoantigens and tumor-associated antigens. Together, these data reveal that OncoVEXmGM-CSF treatment can cause direct tumor lysis along with the potentiation of an adaptive, systemic T cell-mediated anti-tumor immune response that can be enhanced by the addition of PD-L1/PD-1. Our study provides a strong rationale for the ongoing clinical evaluation of the combination of T-VEC and PD1-/PD-L1-targeted therapy in cancer patients.

Citation Format: Keegan Cooke, Juan Estrada, Petia Mitchell, Jinghiu Zhan, Pedro J. Beltran, Jing Qing, Jude Canon. OnxoVEXmGM-CSF promotes systemic response to PD-L1 /PD-1 blockade in multiple mouse syngeneic tumor models [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2219.

Abstract 4558: Antitumor activity of AMG757, a half-life extended (HLE) bispecific T-cell engager (BiTE®) immune therapy targeting DLL3, in human PDX and orthotopic mouse models of small cell lung cancer (SCLC)

SCLC is a highly aggressive neuroendocrine tumor with poor prognosis and limited therapeutic options. Delta-like ligand 3 (DLL3) is a tumor-associated antigen that is highly specific for SCLC; expression is elevated in tumors but minimal and mainly cytoplasmic in normal tissues. AMG 757 is an HLE BiTE® immune therapy that is designed to redirect T-cell cytotoxicity to cancer cells by binding to DLL3 on the surface of cancer cells and CD3 on T cells. AMG 757 is being evaluated in a phase 1 clinical trial in patients with relapsed/refractory SCLC (NCT03319940). We evaluated the efficacy and pharmacodynamic (PD) effects of AMG 757 in three preclinical models of SCLC that express DLL3. We used the LXFS 1129 patient-derived xenograft (PDX) model to assess AMG 757 efficacy in established, subcutaneously implanted tumors similar to human SCLC tumors with their associated stroma. We also developed two orthotopic models of SCLC (SHP-77 and H82) to assess AMG 757 efficacy and PD at biologically relevant sites. In the SHP-77 orthotopic model, cells injected intravenously trafficked to the lungs where they formed diffuse tumors similar to primary SCLC tumors. In the H82 orthotopic model, cells injected intravenously formed discrete metastatic lesions in the liver, mimicking a major site for SCLC metastasis. In each model, mice bearing established tumors received a single infusion of human T cells and were then dosed with AMG 757 or a control HLE BiTE molecule. In the LXFS 1129 PDX model, treatment with AMG 757 induced complete tumor regression in 8 out of 10 mice, whereas treatment with the control HLE BiTE molecule showed no tumor growth inhibition. In the orthotopic SHP-77 model, treatment with AMG 757 led to significant tumor growth inhibition in the lungs relative to treatment with a control HLE BiTE molecule; the bioluminescence (BLI) signal decreased to near the limit of detection 22 days after start of treatment. AMG 757 antitumor activity was associated with increased T-cell trafficking and expansion in tumors; a single dose of AMG 757 significantly increased the number of human CD4+ and CD8+ cells in lungs as assessed by flow cytometry. In the orthotopic H82 model, AMG 757 treatment completely cleared visible lesions from the liver, as assessed by a decrease in BLI to near-background levels and macroscopic analysis of the liver tissue. AMG 757 antitumor activity was associated with increased CD8+ T-cell infiltration as assessed by flow cytometry and IHC and upregulation of the T cell surface activation markers CD25, CD69, PD-1, and 4-1BB as assessed by flow cytometry. Together, these preclinical data demonstrate that AMG 757 can recruit and engage T cells to tumors, consistent with the BiTE® mechanism of action, and that AMG 757-mediated redirected T-cell lysis can drive significant antitumor activity in established SCLC tumor models.

Citation Format: Keegan Cooke, Juan Estrada, Jinghui Zhan, Jonathan Werner, Sean Caenepeel, Mike Giffin, Julie M. Bailis, Angela Coxon, Paul E. Hughes, Jude Canon. Antitumor activity of AMG757, a half-life extended (HLE) bispecific T-cell engager (BiTE®) immune therapy targeting DLL3, in human PDX and orthotopic mouse models of small cell lung cancer (SCLC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4558.

The clinical KRAS(G12C) inhibitor AMG 510 drives anti-tumour immunity

KRAS is the most frequently mutated oncogene in cancer and encodes a key signalling protein in tumours^1,2. The KRAS(G12C) mutant has a cysteine residue that has been exploited to design covalent inhibitors that have promising preclinical activity^3-5. Here we optimized a series of inhibitors, using novel binding interactions to markedly enhance their potency and selectivity. Our efforts have led to the discovery of AMG 510, which is, to our knowledge, the first KRAS(G12C) inhibitor in clinical development. In preclinical analyses, treatment with AMG 510 led to the regression of KRAS^G12C tumours and improved the anti-tumour efficacy of chemotherapy and targeted agents. In immune-competent mice, treatment with AMG 510 resulted in a pro-inflammatory tumour microenvironment and produced durable cures alone as well as in combination with immune-checkpoint inhibitors. Cured mice rejected the growth of isogenic KRAS^G12D tumours, which suggests adaptive immunity against shared antigens. Furthermore, in clinical trials, AMG 510 demonstrated anti-tumour activity in the first dosing cohorts and represents a potentially transformative therapy for patients for whom effective treatments are lacking.

Changing Patterns in the Acute Pain Service: Epidural versus Patient-controlled Analgesia

This study involved an audit and a survey of the Acute Pain Service at Princess Alexandra Hospital. It was found in the audit that the relative choice of epidural analgesia had declined by 50% over the five-year time period of 1998–2003. The survey of consultants showed that 82% of them had changed their practice and that they were performing fewer epidural anaesthetics. Two of the most common reasons given for this change in practice related to fear of litigation (34%) and lack of evidence (21%). These results show that within this department approaches to postoperative pain control had changed and that this appears to have resulted from factors such as the medicolegal environment and the possible influence of evidence based medicine.

Abstract LB-150: Neoantigens that fail to elicit measurable T cell responses following peptide immunization can control tumor growth when delivered using a Listeria-based immunotherapy platform

Introduction: Recent advances in the field of cancer immunotherapy have identified CD8+ T cell responses against tumor-specific neoantigens as a key driver of tumor regression and prolonged survival. ADXS-NEO is a personalized Listeria monocytogenes (Lm)-based immunotherapy designed to generate immune responses against mutation-derived tumor-specific neoantigens. Advaxis' Lm-based immunotherapies consist of live highly-attenuated bacterial vectors that are bioengineered to secrete a fusion protein consisting of a truncated non-hemolytic fragment of listeriolysin O, which has adjuvant properties, and tumor-specific neoantigens that harbor nonsynonymous point mutations (NSMs). The objective of this study is to demonstrate the feasibility of using the ADXS-NEO platform to target tumor-specific point mutations to generate neoantigen-specific T cells and control tumor growth.

Results: Whole-exome sequencing of the MC38 mouse tumor cell line identified 2870 unique NSMs. Among these, the IC50 of 138 NSMs were predicted to be less than 500 nM by the netMHCcons algorithm. We evaluated the immunogenicity of 37 NSMs, and found that 12 immunogenic NSMs elicited a CD8+ T cell response following peptide immunization. Moreover, we identified 10 additional immunogenic NSMs in MC38-bearing mice treated with a check point inhibitor. Altogether, we identified 22 immunogenic and 23 non-immunogenic NSMs. Two ADXS-NEO vectors were constructed, Lm-19 & Lm-20, targeting 19 non-immunogenic and 20 immunogenic NSMs respectively. The ability of Lm-19 and Lm-20 to control MC38 tumor growth was evaluated in C57BL/6J mice. We found that both Lm-19 & Lm-20 led to an accumulation of neoantigen-specific CD8+ TILs and significantly slowed tumor growth. Moreover, both Lm-19 and Lm-20 decreased the frequency and absolute number of intratumoral Tregs, TAMs, and MDSCs and increased the frequency and absolute number of effector CD8+ T cells. Interestingly, expression of PD-L1 was decreased in TAMs and MDSCs and the frequency and total number of granzyme A+ CD8+ effector T cells was increased. Furthermore, the proportion of phenotypically exhausted PD-1hiLAG3+ TILs was decreased. Together, these data suggest the tumor microenvironment in mice receiving Lm-19 and Lm-20 becomes more cytotoxic and less suppressive.

Conclusion: ADXS-NEO is a potent immunotherapy capable of driving immune responses against tumor-specific mutations and leading to tumor control. The effectiveness of the Lm platform is demonstrated by the generation of neoantigen-specific T cells to peptide sequences that were identified as “non-immunogenic” using a conventional peptide-adjuvant immunization. This study is a clear demonstration that T cell mediated anti-tumor responses can be generated by targeting tumor-derived NSMs with the ADXS-NEO Listeria monocytogenes vector.

Citation Format: Brandon Coder, Hyewon Phee, Cristina Mottershead, Dipti Kelkar, Elena Filippova, Xiaoming Ju, Bryan Vander Lugt, Olga Pryshchep, Justin Lesch, Xian Liu, Jason DeVoss, Keegan Cooke, Claret Liu, Jinghui Zhan, Petia Mitchell, Kim Ramos, Daniel O. Villarreal, Jim Johnston, Robert Petit, Michael Princiotta. Neoantigens that fail to elicit measurable T cell responses following peptide immunization can control tumor growth when delivered using a Listeria-based immunotherapy platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-150.

The feasibility and acceptability of a physical activity intervention for older people with chronic musculoskeletal pain: The iPOPP pilot trial protocol

INTRODUCTION

This pilot trial will inform the design and methods of a future full-scale randomized controlled trial (RCT) and examine the feasibility, acceptability and fidelity of the Increasing Physical activity in Older People with chronic Pain (iPOPP) intervention, a healthcare assistant (HCA)-supported intervention to promote walking in older adults with chronic musculoskeletal pain in a primary care setting.

METHODS AND ANALYSIS

The iPOPP study is an individually randomized, multicentre, three-parallel-arm pilot RCT. A total of 150 participants aged ≥65 years with chronic pain in one or more index sites will be recruited and randomized using random permuted blocks, stratified by general practice, to: (i) usual care plus written information; (ii) pedometer plus usual care and written information; or (iii) the iPOPP intervention. A theoretically informed mixed-methods approach will be employed using semi-structured interviews, audio recordings of the HCA consultations, self-reported questionnaires, case report forms and objective physical activity data collection (accelerometry). Follow-up will be conducted 12 weeks post-randomization. Collection of the quantitative data and statistical analysis will be performed blinded to treatment allocation, and analysis will be exploratory to inform the design and methods of a future RCT. Analysis of the HCA consultation recordings will focus on the use of a checklist to determine the fidelity of the iPOPP intervention delivery, and the interview data will be analysed using a constant comparison approach in order to generate conceptual themes focused around the acceptability and feasibility of the trial, and then mapped to the Theoretical Domains Framework to understand barriers and facilitators to behaviour change. A triangulation protocol will be used to integrate quantitative and qualitative data and findings.

Local Delivery of OncoVEXmGM-CSF Generates Systemic Antitumor Immune Responses Enhanced by Cytotoxic T-Lymphocyte-Associated Protein Blockade

Purpose: Talimogene laherparepvec, a new oncolytic immunotherapy, has been recently approved for the treatment of melanoma. Using a murine version of the virus, we characterized local and systemic antitumor immune responses driving efficacy in murine syngeneic models.Experimental Design: The activity of talimogene laherparepvec was characterized against melanoma cell lines using an in vitro viability assay. Efficacy of OncoVEX^mGM-CSF (talimogene laherparepvec with the mouse granulocyte-macrophage colony-stimulating factor transgene) alone or in combination with checkpoint blockade was characterized in A20 and CT-26 contralateral murine tumor models. CD8⁺ depletion, adoptive T-cell transfers, and Enzyme-Linked ImmunoSpot assays were used to study the mechanism of action (MOA) of systemic immune responses.Results: Treatment with OncoVEX^mGM-CSF cured all injected A20 tumors and half of contralateral tumors. Viral presence was limited to injected tumors and was not responsible for systemic efficacy. A significant increase in T cells (CD3⁺/CD8⁺) was observed in injected and contralateral tumors at 168 hours. Ex vivo analyses showed these cytotoxic T lymphocytes were tumor-specific. Increased neutrophils, monocytes, and chemokines were observed in injected tumors only. Importantly, depletion of CD8⁺ T cells abolished all systemic efficacy and significantly decreased local efficacy. In addition, immune cell transfer from OncoVEX^mGM-CSF-cured mice significantly protected from tumor challenge. Finally, combination of OncoVEX^mGM-CSF and checkpoint blockade resulted in increased tumor-specific CD8⁺ anti-AH1 T cells and systemic efficacy.Conclusions: The data support a dual MOA for OncoVEX^mGM-CSF that involves direct oncolysis of injected tumors and activation of a CD8⁺-dependent systemic response that clears injected and contralateral tumors when combined with checkpoint inhibition. Clin Cancer Res; 23(20); 6190-202. ©2017 AACR.

Abstract 3632: BiTE® antibody constructs for the treatment of SCLC

Small cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumor with a poor prognosis and limited therapeutic options. Most patients present with extensive stage disease, where recent advances in immunotherapies, including bi-specific T cell engager (BiTE®) antibody constructs, represent a promising new therapeutic approach. BiTE® molecules have demonstrated durable complete responses in the clinic in hematological malignancies. Similar to hematological malignancies, SCLC is also a widely-disseminated malignancy that shows very high response rate to first line therapies with high rates of disease recurrence, features which may support efficacy of the BiTE® modality. Next generation sequencing (NGS) identified Delta-like Ligand 3 (DLL3) as a highly specific tumor associated antigen for SCLC, with consistent expression in tumors and very low expression in normal tissues. Tumor expression of DLL3 protein was confirmed by IHC, with 30 of 35 SCLC tumors staining positive for DLL3. DLL3 BiTE® antibody constructs showed low pM potency in vitro and also demonstrated significant inhibition of tumor growth in vivo in an orthotopic model of SCLC. A half-life extended (HLE) BiTE® targeting DLL3 demonstrated antibody-like pharmacokinetic properties in single-dose studies in non-human primates (NHP), with a half-life of 11 days. This is predicted to support every other week dosing in humans. The combination of high potency and excellent PK properties suggests that HLE BiTE® molecules may provide a useful tool for targeting residual disease in SCLC patients whose tumors express DLL3.

Citation Format: Michael J. Giffin, Ed K. Lobenhofer, Keegan Cooke, Tobias Raum, Jennitte Stevens, Pedro J. Beltran, Angela Coxon, Paul E. Hughes. BiTE® antibody constructs for the treatment of SCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3632. doi:10.1158/1538-7445.AM2017-3632

Abstract 4566: OncoVEXmGM-CSF (HSV-1 modified similarly to Talimogene Laherparepvec) in combination with CTLA-4 blockade leads to both local and systemic efficacy in a murine syngeneic model of metastatic melanoma

Talimogene laherparepvec is an oncolytic immunotherapy based on a modified herpes simplex virus type 1 (HSV-1) designed to kill cancer cells through two mechanisms: a) direct viral-mediated lysis and b) stimulation of a tumor antigen-specific adaptive immune response. We developed a mouse model of metastatic melanoma using the B16F10 cell line to study local and systemic responses following treatment with talimogene laherparepvec alone or in combination with CTLA-4 blockade. OncoVEXmGM-CSF, an HSV-1 modified similarly to talimogene laherparepvec (murine GM-CSF is expressed instead of human GM-CSF) was used in these studies.

B16F10 cells have been reported to be resistant to HSV-1 infection due to a lack of requisite entry receptors. To overcome resistance, we transduced B16F10 cells with a lentiviral vector expressing mouse nectin1 (mNectin1) or eGFP as a control. Expression was confirmed by ddPCR and sensitivity to OncoVEXmGM-CSF evaluated in an in vitro viability assay. B16F10-mNectin1 cells were highly sensitive to OncoVEXmGM-CSF with a multiplicity of infection (MOI) IC50 of 0.001 (B16F10-eGFP were insensitive at MOI of 100). In vivo, B16F10-mNectin1 and B16F10-eGFP cells showed similar growth when injected subcutaneously. OncoVEXmGM-CSF treatment of B16F10-mNectin1 tumors (intratumoral, 5x106 PFU/dose, 3X) caused a significant (p&lt;0.0001) inhibition of tumor growth and prolonged median overall survival compared to control animals. To assess the local and systemic effect of OncoVEXmGM-CSF in combination with CTLA-4 blockade, we developed a model of experimental metastatic melanoma by delivering the B16F10-eGFP cells intravenously (systemic, non-injectable tumors) on day 0 and implanting the B16F10-mNectin1 cells SC (local, injectable tumors) on day 2. Mice were dosed with OncoVEXmGM-CSF and anti-CTLA-4 antibody 9D9 (100ug/dose) every 3 days between days 12 and 19. Subcutaneous tumor growth inhibition was assessed and lung metastasis were quantified on day 28. Both OncoVEXmGM-CSF and CTLA-4 treatment significantly inhibited subcutaneous tumor growth and lung metastasis. The combination of both therapeutics resulted in significantly greater local and systemic efficacy than either agent alone. The strong local and systemic anti-tumor activity of the combination resulted in a significant increase in median overall survival (p&lt;0.0001) compared to control mice that received intravenous B16F10-eGFP cells only.

In conclusion, OncoVEXmGM-CSF in combination with CTLA-4 blockade significantly reduced systemic tumor burden and prolonged median overall survival in a B16F10 mouse model of metastatic melanoma. These data support the proposed MOA by which OncoVEXmGM-CSF treatment can cause direct tumor lysis along with potentiation of an adaptive, systemic anti-tumor immune response.

Citation Format: Keegan Cooke, Juan Estrada, Jinghui Zhan, David Hill, Andrea Boden, Jon Werner, Pedro J. Beltran. OncoVEXmGM-CSF (HSV-1 modified similarly to Talimogene Laherparepvec) in combination with CTLA-4 blockade leads to both local and systemic efficacy in a murine syngeneic model of metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4566. doi:10.1158/1538-7445.AM2017-4566

Abstract 2346: Intratumoral administration of OncoVEXmGM-CSF results in local innate immune alterations and induces systemic anti-tumor effects in syngeneic mouse tumor models

Talimogene laherparepvec, is a modified oncolytic herpes simplex virus type-1 (HSV-1) designed to selectively replicate in tumors and to initiate a systemic immune response to target cancer cells. Intralesional administration of talimogene laherparepvec is intended to result in oncolysis within injected tumors, with lytic cell destruction promoting the local release of progeny virus and tumor derived antigens. GM-CSF, a product of the viral transgene, is also produced locally and is designed to recruit and stimulate antigen presenting cells to further enhance systemic antitumor immune response.

While available evidence suggests that talimogene laherparepvec can induce effects in distant tumors via an immune-mediated effect, additional mechanistic evidence is being sought to help better understand the putative systemic effect. For preclinical mechanism of action studies we employed OncoVEXmGM-CSF, an HSV-1 virus modified in the same manner as talimogene laherparepvec except that murine GM-CSF is expressed. We utilized this virus to further dissect the underlying innate and adaptive immunity following viral administration in syngeneic tumor models.

Intratumoral administration of OncoVEXmGM-CSF into established murine tumors induced regressions in the injected lesion but also resulted in significant anti-tumor effects in contralateral (uninjected) lesions. We have previously demonstrated by immunohistochemistry that the systemic effects observed in the contralateral lesions are not driven by systemic spread of the virus, but instead correlate with the infiltration of CD3+ T cell populations. Here we report the full phenotypic characterization of immune infiltrates by flow cytometry in both the injected and contralateral lesions. In a time-course fashion, this characterization revealed the initial infiltration of the injected tumor by innate effector cells and a concomitant induction of a potent type I interferon response. This in turn drives the local release of proinflammatory cytokines and chemokines, resulting in the recruitment of adaptive immune subsets to the injected tumor and enhancing systemic anti-tumor reactivity. Additionally, both the primary oncolytic replication of the virus and the activation of type I interferon pathway are directly correlated with STING activity.

In conclusion, in vitro and in vivo observations suggest that intratumoral injection of OncoVEXmGM-CSF activates multiple immune-mediated mechanisms of action leading to T-cell activation and induction of anti-tumor immunity in mice.

Citation Format: Keegan Cooke, Karen Fitzgerald, Becky Yang, Juan Estrada, Brian Belmontes, Pedro Beltran, Achim K. Moesta. Intratumoral administration of OncoVEXmGM-CSF results in local innate immune alterations and induces systemic anti-tumor effects in syngeneic mouse tumor models. [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 2346.

Oxopyrido[2,3-d]pyrimidines as Covalent L858R/T790M Mutant Selective Epidermal Growth Factor Receptor (EGFR) Inhibitors

In nonsmall cell lung cancer (NSCLC), the threonine(790)-methionine(790) (T790M) point mutation of EGFR kinase is one of the leading causes of acquired resistance to the first generation tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib. Herein, we describe the optimization of a series of 7-oxopyrido[2,3-d]pyrimidinyl-derived irreversible inhibitors of EGFR kinase. This led to the discovery of compound 24 which potently inhibits gefitinib-resistant EGFR(L858R,T790M) with 100-fold selectivity over wild-type EGFR. Compound 24 displays strong antiproliferative activity against the H1975 nonsmall cell lung cancer cell line, the first line mutant HCC827 cell line, and promising antitumor activity in an EGFR(L858R,T790M) driven H1975 xenograft model sparing the side effects associated with the inhibition of wild-type EGFR.

Abstract 2587: A novel covalent inhibitor of mutant but not wild-type (WT) epidermal growth factor receptor (EGFR) has activity in vitro and in vivo in non-small cell lung cancer (NSCLC) models

Background: Mutations in the EGFR kinase are common in NSCLC. Patients with first-line EGFR mutations (exon 19 deletions, L858R mutations, exon 20 variants, codon 719 variants) initially respond to the reversible EGFR inhibitors erlotinib and gefitinib, but then relapse as additional mutations emerge. EGFR T790M is the most common of these mutations and is found in &gt; 50% of refractory tumors. We assessed the in vitro and in vivo activity of CPD 24, a newly developed, covalent, small-molecule inhibitor of both first-line and T790M mutant EGFR, but not WT EGFR. Inhibition of WT EGFR in normal tissues can be a source of dose-limiting toxicities.

Methods: The effects of CPD 24 were evaluated on H1975 (EGFR T790M/L858R), HCC827 (EGFR exon 19 deletion), and A431 (WT) cell lines. Inhibition of EGFR phosphorylation was measured in serum-starved cells using an MSD assay. Viability was assessed by measuring ATP in cells using a CellTiter-Glo® assay. Dose- and time-dependent pharmacodynamic effects were evaluated by treating mice bearing matrigel plugs containing H1975 cells. Drug levels were measured in plasma samples by LC-MS. CPD 24 was administered to athymic nude mice bearing H1975, HCC827, or A431 xenografts (3, 10, and 30 mg/kg, QD, PO) and tumor growth was measured twice per week with digital calipers. CPD 24 was also formulated in PLGA microspheres and administered subcutaneously (SC) as a sustained release formulation to mice bearing H1975 or A431 xenografts (30 and 100 mg/kg, Q3D, SC). Proliferation of H1975 and HCC827 cells in the presence of CPD 24, growth factors, and a MET inhibitor was measured with an IncuCyte live-cell imaging system.

Results: The IC50 of CPD 24 for p-EGFR inhibition was 4 nM on L858R/T790M mutant EGFR (H1975 cells), 17 nM on the exon 19 deletion EGFR (HCC827 cells), and 510 nM on WT EGFR (A431 cells). CPD 24 inhibited the growth of tumor cells in vitro and led to both dose- and time-dependent p-EGFR inhibition in vivo. Phosphorylation of EGFR in H1975 cells growing in matrigel plugs was inhibited by &gt; 75% for 12 hours by a single 30 mg/kg dose. Tumor growth inhibition (TGI) was observed in two EGFR mutant NSCLC xenograft models (H1975, 89% TGI; HCC827, 139% TGI) but not in a WT EGFR model (A431). CPD 24 formulated in PLGA microspheres achieved drug levels above the IC50 for 72 hours after a single SC dose. Tumor regression was observed with this formulation in H1975 xenografts but not in WT tumors. HGF was able to confer resistance to CPD 24 inhibition in both H1975 and HCC827 cells in vitro. This resistance was prevented by the addition of a selective MET inhibitor.

Conclusion: CPD 24 is a covalent inhibitor of both first-line and T790M mutant EGFR while maintaining &gt; 100-fold selectivity over WT EGFR. The antiproliferative effects of CPD 24 can be reversed by HGF, and this resistance can be prevented by treatment with a MET inhibitor.

Citation Format: Pedro J. Beltran, Jinghui Zhan, Petia Mitchell, Ryan P. Wurz, Liping Pettus, Tian Wu, Mary Chaves, Darren L. Reid, Robert Radinsky, Keegan Cooke, Andrew Tasker. A novel covalent inhibitor of mutant but not wild-type (WT) epidermal growth factor receptor (EGFR) has activity in vitro and in vivo in non-small cell lung cancer (NSCLC) models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2587. doi:10.1158/1538-7445.AM2015-2587

Abstract 3712: HGF mediated resistance to BRAF inhibition in BRAF V600E mutant melanoma xenograft models

Background: A key obstacle in the treatment of cancer is resistance to targeted therapy. Recent reports suggest that growth factors and their receptors may play a role in mediating this resistance. HGF/MET signaling has been shown to play a role in mediating resistance to BRAF inhibitors in BRAF mutant melanoma. We studied the role of HGF/MET in mediating resistance to BRAF inhibition in BRAF mutant melanoma xenografts, comparing models of systemic and local HGF expression and evaluating the ability of a MET inhibitor to reverse HGF mediated resistance. The underlying mechanisms of this resistance were evaluated by monitoring changes in PI3K and MAPK signaling. Our data suggest that elevated local HGF expression may be required for resistance to BRAF inhibition in vivo and that resistance can be reversed by treatment with a MET inhibitor.

Methods: To model systemic HGF expression, mice bearing G361 melanoma xenografts were treated with recombinant adeno-associated virus containing an expression cassette for human HGF (AAV-HGF) or GFP as control. Mice were treated with C-1 (10 mg/kg, QD, PO), a BRAF inhibitor, or vehicle, and tumor growth was monitored. Local HGF expression was modeled using G361 xenografts engineered to express HGF under the control of an inducible promoter (tet-HGF). Mice bearing G361 tet-HGF xenografts, with or without doxycycline, were treated and monitored as described above. A follow up study was performed in G361 tet-HGF xenografts to measure the ability of AMG 337 (20 mg/kg, BID, PO), a selective MET inhibitor, to attenuate the HGF mediated rescue of BRAF inhibition. To monitor effects on the PI3K and MAPK pathways, pAKT and pERK levels were measured in tumors. Plasma and tumor HGF levels were also measured.

Results: Systemic expression of HGF via AAV-HGF treatment failed to rescue G361 xenografts from the growth inhibitory effects of C1. In contrast, local doxycycline-induced expression of HGF in mice harboring G361 tet-HGF xenografts conveyed significant (p&lt;0.001) rescue of tumor growth, suggesting that local HGF expression may be required to mediate BRAF inhibitor resistance. Elevated pAKT and pERK levels were detected in HGF rescued tumors, suggesting that PI3K and MAPK signaling pathways play a role in conveying HGF mediated resistance. Combined treatment with AMG 337 prevented the HGF mediated rescue of BRAF inhibition, confirming the role of MET signaling in this rescue mechanism. Plasma HGF levels in mice from the systemic HGF expression groups exceeded those in the local groups (3,049 and 195 pg/mL). However, tumor HGF levels were higher in the local expression groups compared to the systemic groups (26,400 and 477 pg/mL).

Conclusion: Here we demonstrate the role for HGF/MET signaling in mediating resistance to BRAF inhibitors in melanoma and suggest that monitoring HGF levels may be of clinical utility for predicting response to BRAF inhibition and in defining the opportunity for combination therapy with MET inhibitors.

Citation Format: Keegan Cooke, Guo Huang, Sean Caenepeel, Hong Ma, Cherylene Plewa, Ki Jeong Lee, Angela Coxon, Paul E. Hughes, Pedro Beltran. HGF mediated resistance to BRAF inhibition in BRAF V600E mutant melanoma xenograft models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3712. doi:10.1158/1538-7445.AM2014-3712

Molybdenum doped titanium dioxide photocatalytic coatings for use as hygienic surfaces: the effect of soiling on antimicrobial activity

Titanium dioxide (TiO2) surfaces doped with molybdenum (Mo) were investigated to determine if their photocatalytic ability could enhance process hygiene in the brewery industry. Doping TiO2 with Mo showed a 5-log reduction in bacterial counts within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h. The presence of a dilute brewery soil on the surface did not interfere with antimicrobial activity. The TiO2-Mo surface was also active in the dark, showing a 5-log reduction in bacteria within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h, suggesting it could have a novel dual function, being antimicrobial and photocatalytic. The study suggests the TiO2-Mo coating could act as a secondary barrier in helping prevent the build-up of microbial contamination on surfaces within the brewery industry, in particular in between cleaning/disinfection regimes during long production runs.

The effect of vascular risk factors on the efficacy of rivastigmine patch and capsule treatment in Alzheimer's disease

Background

Vascular risk factors (VRF) may influence response to rivastigmine in Alzheimer's disease (AD).

Methods

AD patients who participated in a randomized, double-blind, placebo-controlled trial of rivastigmine patch and capsule treatment were stratified by baseline VRF status. Treatment response was evaluated using the AD Assessment Scale-cognitive subscale (ADAS-cog), AD Cooperative Study-Clinical Global Impression of Change (ADCS-CGIC) and the AD Cooperative Study-Activities of Daily Living (ADCS-ADL) scale.

Results

ADAS-cog scores significantly improved in all rivastigmine-treated patients (p < 0.05 vs. placebo), except 9.5 mg/24 h patch-treated patients with VRF, and were significantly affected by VRF status in the study population as a whole. Significant benefits were seen on the ADCS-ADL in 9.5 mg/24 h patch- and capsule-treated patients with, but not without, VRF. The ADCS-CGIC significantly improved in capsule-treated patients with, and patch-treated patients without VRF. Although non-significant, patients without VRF showed an apparent faster rate of placebo decline.

Conclusion

VRF may influence AD progression and response to rivastigmine.

Early experience of tomotherapy-based intensity-modulated radiotherapy for breast cancer treatment

AIMS

New technology - specifically intensity-modulated radiotherapy (IMRT) - is now being applied to breast radiotherapy and a recent dosimetric analysis confirmed the advantages of IMRT over 'wedge-only' plans. Such application to everyday practice raises new issues and here we present the early experience of IMRT-based breast irradiation in a single centre.

MATERIALS AND METHODS

We present cases of breast cancer treated by Tomotherapy-based IMRT, where the perceived advantages of IMRT are considerable. Cases presented are bilateral disease, left breast irradiation, pectus excavatum, prominent contralateral prosthesis and internal mammary chain disease. We discuss the practicalities of such treatment and the advantages over standard breast irradiation techniques.

RESULTS

Advantages include better conformity of treatment with lowering of dosages to underlying organs at risk, for example ipsilateral lung and heart. There is improved coverage of the planning target volume, including regional nodes, without field junction problems. Planning, quality assurance and treatment delivery are more time consuming than for standard breast irradiation and the low dose 'bath' is increased.

CONCLUSIONS

The standard radiotherapy tangential technique for breast/chest wall treatments has not significantly changed over many decades, whereas across many other tumour sites there have been great advances in radiotherapy technology. The dosimetric advantages of IMRT are readily apparent from our early experience. The wider spread of the lower dose zone (the low dose 'bath' of radiation) is a potential concern regarding late oncogenesis and methods to minimise such risks should be considered.

A dosimetric comparison between two intensity-modulated radiotherapy techniques: tomotherapy vs dynamic linear accelerator

This manuscript describes a direct comparison between radiation treatment plans in terms of dosimetric outcomes created by two different IMRT systems: TomoTherapy HiArt and dynamic linac intensity-modulated radiotherapy (dIMRT). Three patient cases were selected (with disease in different anatomical areas): vertebral metastasis re-treatment, radical prostate therapy and an ethmoid sarcoma re-treatment. Each case presents significant and varying dosimetric difficulties with respect to avoidance of adjacent organs. The patients were each planned and treated at the Cromwell Hospital (London, UK) using the TomoTherapy HiArt system, with planning replicated at St Bartholomew's Hospital (London, UK) using Eclipse Treatment Planning System and a 6EX linac with a 120-leaf multileaf collimator (Varian Medical Systems). For both modalities, all treatment plans conformed to the stringent clinical dose constraints set. For the vertebral body re-treatment, both techniques demonstrated adequate and similar planning target volume (PTV) coverage and sparing of the spinal cord. The critical structure sparing and PTV coverage for the prostate treatment was again similar for both modalities. For re-treatment of the paediatric ethmoid sarcoma, tomotherapy was able to produce slightly better organ sparing whilst producing PTV coverage similar to linac dIMRT. The data presented in this manuscript demonstrate subtle dosimetric differences between the two techniques but no marked advantage with either system. Therefore, other factors may need to be considered when making a decision between tomotherapy and linac dIMRT.

Predictors of Oxygen Uptake and Performance During Tennis

Tennis ball machine tests permit the concurrent measurement of physiological function and groundstroke performance in a sport specific manner. The purpose of this study was to understand further the demands of groundstroke performance during a test with progressively increasing ball frequency, by determining the running speed between strokes, upper and lower limb acceleration and pulmonary gas exchange throughout. Sixteen tennis players (n = 8, male; n = 8, female; all right handed) completed three 4 min stages of hitting against a ball feed frequency of 15, 20, 25 ball.min(-1) interspersed by 8 min of rest. Stepwise multiple regression analysis identified a predictive model of VO2 containing the variables of left arm acceleration and right ankle acceleration but not running speed (p < 0.0001; adjusted r2 = 0.93; left wrist acceleration Beta = 1.04; right ankle acceleration Beta = - 0.12; S. E. E. = 2.61 ml.kg(-1).min(-1)). Regression analysis found that the strongest predictors of stroke performance (ball speed [m.s(-1)] x stroke accuracy [%]) were right wrist acceleration and stroke economy (p < 0.0001; adjusted r2 = 0.28; right wrist acceleration Beta = - 0.59; movement economy Beta = - 0.28). The findings of this study highlight the contribution of limb acceleration and not running speed to the oxygen cost of tennis groundstroke performance.

The reliability and validity of a field hockey skill test

High test retest reliability is essential in tests used for both scientific research and to monitor athletic performance. Thirty-nine (20 male and 19 female) well-trained university field hockey players volunteered to participate in the study. The reliability of the in house designed test was determined by repeating the test (3 - 14 days later) following full familiarisation. The validity was assessed by comparing coaches ranks of players with ranked performance on the skill test. The mean difference and confidence limits in overall skill test performance was 0.0 +/- 1.0 % and the standard error (confidence limits) was 2.1 % (1.7 to 2.8 %). The mean difference and confidence limits for the "decision making" time was 0.0 +/- 1.0 % and the standard error (confidence limits) was 4.5 % (3.6 to 6.2 %). The validity correlation (Pearson) was r = 0.83 and r = 0.73 for female players and r = 0.61 and r = 0.70 for male players for overall time and "decision making" time respectively. We conclude that the field hockey skill test is a reliable measure of skill performance and that it is valid as a predictor of coach-assessed hockey performance, but the validity is greater for female players.

Novel erythropoiesis stimulating protein (darbepoetin alfa) alleviates anemia associated with chronic inflammatory disease in a rodent model

OBJECTIVE

We developed a rodent model of noninfectious systemic inflammation to examine the pathogenesis of the associated anemia of chronic disorders (ACD), to evaluate the similarity of this ACD model to human ACD, and to evaluate the potential efficacy of novel erythropoiesis stimulating protein (darbepoetin alfa) as an ACD therapy.

METHODS

Lewis rats were immunized with peptidoglycan-polysaccharide polymers (PG-APS), the chronic inflammation and associated ACD were characterized, and the effects of darbepoetin alfa treatment on complete blood counts (CBC), red blood cell (RBC) indices, and iron metabolism were analyzed weekly.

RESULTS

Acutely inflamed rats had reduced peripheral blood (PB) RBC counts and hemoglobin (Hb) concentrations and increased reticulocyte counts. PB RBC numbers normalized during chronic inflammation, but RBC remained hypochromic and microcytic. Consequently, the rats remained chronically anemic. Anemic rats had fluctuating serum erythropoietin (EPO) concentrations, but mean EPO concentrations never varied significantly from baseline control levels. Histology of anemic rat spleen sections revealed reticuloendothelial siderosis. Total serum iron concentrations were chronically low. Peritoneal exudate cells (PEC) isolated from anemic rats and stimulated with PG-APS in vitro produced more interleukin (IL)-1alpha and interferon (IFN)-gamma, and significantly more tumor necrosis factor (TNF)-alpha and IL-10 than control cultures. Darbepoetin alfa restored Hb concentrations to baseline levels within 2 to 7 weeks, depending on dosage. A refined treatment strategy restored Hb to baseline and maintained those levels with reduced dosing.

CONCLUSION

ACD in this rodent model closely replicates human ACD. Darbepoetin alfa treatment reversed ACD in this model by increasing RBC production and RBC hemoglobinization while reducing siderosis and hypoferremia.

Behaviour change and treatment of core groups: its effect on the spread of HIV/AIDS

A general model is considered for treatment and behaviour change of the Human Immunodeficiency Virus (HIV) infected in a highly sexually active core group of female commercial sex workers (CSWs) and a 'bridge population' of young unpartnered males. In this model, the spread of HIV/AIDS in the community is carried out mainly through the sexual interaction between the core group and the bridge population which acts as a bridge for the spread of disease to the general population. We will consider the effect of treatment of the infected and/or the subsequent behaviour change when targeted toward the core group and the bridge population. Analytical results will be given for a strategy which targets treatment and behaviour change at either the core group or the bridge population. Numerical examples are also provided to illustrate the biological significance of the treatment/behaviour change and its effect on the threshold parameter values. The results show that if the contact rates and transmission probabilities of the treated individuals are sufficiently reduced, the treatment/behaviour change can eradicate the disease provided that the level of treatment in the infected population is sufficiently high. However, an ill-planned treatment program which fails to meet the required reductions in contact rate or transmission probability could have a detrimental effect on the spread of the epidemic.

Interaction of maturation delay and nonlinear birth in population and epidemic models

A population with birth rate function B(N) N and linear death rate for the adult stage is assumed to have a maturation delay T>0. Thus the growth equation N'(t)=B(N(t-T)) N(t-T) e(-)d(1)T- dN(t) governs the adult population, with the death rate in previous life stages d(1)>==0. Standard assumptions are made on B(N) so that a unique equilibrium N(e) exists. When B(N) N is not monotone, the delay T can qualitatively change the dynamics. For some fixed values of the parameters with d(1)>0, as T increases the equilibrium N(e) can switch from being stable to unstable (with numerically observed periodic solutions) and then back to stable. When disease that does not cause death is introduced into the population, a threshold parameter R(0) is identified. When R(0)<1, the disease dies out; when R(0)>1, the disease remains endemic, either tending to an equilibrium value or oscillating about this value. Numerical simulations indicate that oscillations can also be induced by disease related death in a model with maturation delay.

Natural killer and lymphokine-activated cytotoxicity following anaesthesia in patients with uveal malignant melanoma

The role of enucleation in the treatment of ocular melanoma has been questioned by those who believe that it may increase circulating melanoma cells, increasing the incidence of metastases. Some aspects of the immune system are depressed by general anaesthesia, therefore this study was initiated to assess the effect of general anaesthesia on natural killer (NK) cell and interleukin-2 (IL-2)-activated cytotoxicity in 19 patients using 51Cr-labelled target cells (K 562 and SW 742). NK cytotoxicity was increased at induction and during the operation which was due to significant increases in female, but not male patients. At 1 week post-surgery, female patients had decreased NK cytotoxicity compared with males at this interval. NK cytotoxicity compared with males at this interval. NK cytotoxicity was increased intra-operatively when alfentanyl was used, and if the mean tumour diameter was > 15.0 mm the NK cytotoxicity was increased intra-operatively compared with that in patients with smaller tumours. IL-2-stimulated cytotoxicity was reduced at 1 day post-surgery in females only. There was an increased IL-2-stimulated cytotoxicity at induction when propofol was used and IL-2-stimulated cytotoxicity was reduced at 1 week post-operatively if the patient's mean tumour diameter was > 15.0 mm. If NK cell and lymphokine-stimulated cell cytotoxicity are involved in limiting metastatic disease, the patient' sex and tumour size and the anaesthetic agent used may influence the survival rates following surgery.

A model for HIV in Asia

A model is proposed in which the spread of HIV/AIDS in the community is mainly due to the sexual interaction between a core group of female prostitutes and young unmarried males. Several threshold parameters are obtained that determine persistence of endemic proportions, persistence of total population, and the persistence of infective population given the extinction of endemic proportions in a population tending to infinity. Conditions are given for the existence of multiple endemic equilibria as well as the existence of multiple stable equilibria with separatrix and their asymptotic behavior and biological significance are discussed. In all cases, global analysis is accompanied by bifurcation diagrams, and numerical examples are provided for some particular cases of interest. This model was proposed with the recent rapid growth of the HIV/AIDS epidemic in Asia in mind.

MR urography: technique and application

PURPOSE

To evaluate a magnetic resonance (MR) technique for depicting the kidneys and urinary tract.

MATERIALS AND METHODS

Fourteen patients with urinary tract obstruction and 20 without obstructions were examined with a modified, heavily T2-weighted fast spin-echo pulse sequence (MR urography). In addition, six healthy volunteers underwent modified MR urography with intravenous administration of furosemide and ureteral compression prior to imaging.

RESULTS

MR urography provided high-resolution images of the kidneys and urinary tract in all patients with obstruction with intact collecting systems. Anatomic anomalies were depicted in two patients. Intraluminal neoplasia was well demonstrated in both obstructed and nonobstructed systems (n = 4). Furosemide-enhanced MR urography provided fine anatomic and functional detail of both the kidneys and urinary tract (n = 6).

CONCLUSION

MR urography may provide an alternative to more conventional urinary tract imaging techniques. It does not require ionizing radiation or iodinated contrast material. When combined with furosemide and ureteral compression, MR urography provides fine detail and reflects function.

General practice consultations involving pigmented naevi presented for assessment of malignancy

AIM

To outline the initial general practice care of pigmented naevi presented for assessment of malignancy.

METHOD

Fifty six general practitioners completed a brief record for each patient presenting a pigmented skin lesion for assessment of malignancy; records were maintained prospectively for periods over October 1988 to April 1989. 2614 records were received.

RESULTS

Numbers of consultations increased sharply with age to peaks at 15-19 for men and 30-44 for women; at ages 20 44 the sex ratio was 1.9 (F/M). Lesions were usually typical (51%) or atypical (24%) moles. 22% of patients were biopsied by the practitioner and 8% were referred, to dermatologists (4%) or surgeons (4%).

CONCLUSIONS

The age pattern of presentations is younger than is optimal. General practitioners' decisions and actions are of crucial importance in the effective functioning of melanoma early detection programmes.

Radioprotection of mice by recombinant rat stem cell factor

Treatment with recombinant rat stem cell factor (rSCF) protects mice from the lethal effects of irradiation. Mice treated with a single dose of rSCF prior to irradiation of up to 1150 rads [given as a split dose (1 rad = 0.01 Gy)] resulted in > 80% long-term survival, whereas a single injection given after the last dose of irradiation was not radioprotective. The combination of pre- and posttreatment (-20 h, -2 h, and +4 h) with rSCF resulted in 100% survival of otherwise lethally irradiated mice. Using this optimum schedule of rSCF administration, a radioprotective factor of 1.3-1.35 was achieved. The major cause of death in the control animals was massive bacteremia consisting of enteric organisms. The rSCF-treated animals had a much lower frequency of septicemia, due primarily to a rapid hematopoietic recovery of bone marrow function not evident in control animals.

Primary malignant melanoma of skin in four regions of New Zealand

AIMS

to describe the incidence and thickness of a representative collection of melanomas occurring in recent years in New Zealand.

METHODS

all pathology reports of primary malignant melanoma of the skin, in defined periods in 1987-9, were collated for four regions of New Zealand.

RESULTS

nonMaori incidence rates were 52 and 58 melanomas per 100,000 person years for men and women, respectively. These rates are much higher than the 24 per 100,000 person years for melanoma registrations in 1983-4. The age standardised invasive melanoma rate of 35 per 100,000 person years was higher than those of most Australian states and close to the rate for Queensland in 1986. Preinvasive melanomas comprised 26% of all melanomas. Of invasive melanomas, 58% in men and 55% in women were less than 0.76 mm in thickness; 7% of invasive melanomas in men and 5% in women were at least 3.5 mm thick.

CONCLUSIONS

increasingly early detection of malignant melanomas in successive years is likely to have contributed to the recent increase in incidence, perhaps to a major degree, but an environmental cause cannot be excluded.

Growth in children after bone marrow transplantation for advanced neuroblastoma compared with growth after transplantation for leukemia or aplastic anemia

The linear growth of 26 children with progressive and advanced neuroblastoma treated with high-dose chemotherapy, total body irradiation, and bone marrow transplantation between 1978 and 1988 at the Children's Hospital of Philadelphia was compared with the growth of 33 children who had transplants for leukemia and of 12 who had transplants for aplastic anemia. The mean growth velocity, expressed as a standard deviation score, for the children who underwent bone marrow transplantation for neuroblastoma was -2.83. This was significantly (p less than 0.005) less than the standard deviation scores for children with transplants for acute lymphoblastic leukemia, acute nonlymphocytic leukemia, and aplastic anemia, which were -0.98, -0.07, and -1.05, respectively. A 6-year follow-up study of 32 long-term survivors of cancer revealed that the 11 patients with neuroblastoma continued to grow poorly, whereas a comparison group of 21 survivors of bone marrow transplantation for leukemia had essentially normal growth 2 years after the procedure. Major therapeutic differences between the two groups included the doses of local radiotherapy and the type and number of cytotoxic agents used. In comparison with the relatively mild growth-inhibiting effects of preparative regimens for leukemia and aplastic anemia, the very intensive preparative regimens used in patients with neuroblastoma have significant negative effects on growth.

Trends in nonmelanoma skin cancer mortality

Nonmelanoma skin cancer mortality rates for recent decades show a biphasic pattern: from 1950-65 rates decreased; from 1966-86 rates increased. Age standardised mortality rates for 35-74 year old males increased from 1.6 (95% CI, 1.3-1.9) deaths per 100,000 person years in 1966-72 to 2.3 (95% CI, 2.0-2.5) deaths per 100,000 person years in 1980-86. Rates in women were lower but showed a similar percentage increase (46%), between these periods, to that observed for men (44%). The increased mortality from 1966 was presumably a result of increased ultraviolet exposure.

The health effects of aluminium--a review

This review covers the occurrence of aluminium in soil, air, water and food. In addition, aluminium levels in body tissues and its movement within the body have been considered. The adverse effects of aluminium that have been reported in recent years include Alzheimer's disease, dementia and hyperactivity and learning disorders in children.

Perceptions of pain relief after surgery

OBJECTIVE

To assess patients' satisfaction with postoperative pain relief.

DESIGN

A descriptive and questionnaire study of patients' experience.

SETTING

Two surgical and two gynaecological wards.

PATIENTS

50 Patients admitted to hospital for cholecystectomy and 51 admitted for hysterectomy.

MAIN OUTCOME MEASURES

Visual analogue scales with no divisions were completed by the patients immediately after each dose of postoperative analgesia was administered throughout their stay in hospital. A questionnaire completed on the fifth postoperative day recorded patients' recollections of their experience. Opinions were also sought from medical and nursing staff.

RESULTS

During the first 24 hours after surgery recorded pain levels were 60% of the maximum and were not influenced by age, sex, or the type of operation performed. The median interval between the return of pain and a further injection of analgesic was 2 hours (interquartile range 1 to 3.5 hours). Expectations of pain relief were low, and for 70% of the patients the pain was at least as bad as they had expected. Only half of the medical and nursing staff questioned thought that postoperative analgesia should relieve pain completely; drugs were prescribed and administered with too little attention to the patient's response and too much concern about adverse effects and opioid dependence.

CONCLUSIONS

The results suggest that the standard of postoperative pain relief is poor because of inadequate education of patients in what to expect (and demand), and of medical and nursing staff in how to prescribe and administer analgesia with reference to individual drug response.