Exposure-response (E-R) efficacy and safety (E-S) analyses of tremelimumab as monotherapy or in combination with durvalumab in patients (pts) with unresectable hepatocellular carcinoma (uHCC)

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Background: In a phase II study in uHCC (Study 22, NCT02519348), a novel, priming combination regimen of tremelimumab (T; anti-CTLA-4) and durvalumab (D; anti-PD-L1) (T300+D) has shown favorable clinical activity vs each agent as monotherapy or vs another combination (T75+D). The analyses presented here assess the pharmacokinetics (PK) and relationships between tremelimumab exposure, as monotherapy or in combination, and safety, efficacy, and pharmacodynamics (PD) in this study. Methods: Overall, 216 pts were included in these analyses (T, n=65; T300+D, n=72; T75+D, n=79). Safety, antitumor activity, PK, PD, and immunogenicity were analyzed using standard pharmacometrics methods. A previously developed population PK model for T across solid tumors was validated using T monotherapy and combination therapy data from Study 22, including a post-hoc covariate analysis to assess the impact of covariates on individual PK parameters. Population PK and PD models related individual T exposures to safety parameters, PD, and efficacy (overall survival, OS; progression-free survival, PFS; and objective response rate, ORR). The E-R relationships for time-to-event variables OS and PFS were explored by Kaplan-Meier estimates and analyzed by Cox proportional-hazards models (CPHM). Results: For T monotherapy and T+D combinations, no significant E-S relationships were observed for grade 3/4 treatment-related adverse events (TRAEs), grade 3/4 TRAEs of special interest, and AEs leading to treatment discontinuation. Analyses of each quartile of T exposure suggest pts with higher exposure (3rd and 4th quartile) may have longer OS vs lower quartiles. The CPHManalysis showed that after accounting for prognostic factors (baseline albumin and neutrophil-to-lymphocyte ratio), neither AUC nor Cmin appeared to be a significant factor for OS hazard. There was no significant relationship between response and ORR, PFS and any T PK exposure metric in T-treated pts. Saturable relationships (described by Emax) were observed for maximum change from baseline for proliferating T-cell counts as functions of exposure. Conclusions: The observed PK data are generally consistent with predictions based on a historical population PK model, suggesting the PK of T in uHCC pts is consistent with pts with other solid tumors. No significant relationships were observed between E-S and E-R; therefore, PK is not a significant predictor to evaluate for T efficacy or safety. Considering the small sample size limitation, still the saturable relationships observed in proliferating T-cells appear to support a dose of T300. Future studies of pooled data from Study 22 and the larger phase III HIMALAYA study (NCT03298451) will be conducted to further the characterization of E-R relationships and the development of the T300+D regimen. Clinical trial information: NCT02519348.

Overall survival modeling and association with serum biomarkers in durvalumab-treated patients with head and neck cancer

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Background: Optimal patient selection for immunotherapy remains a challenge as most patients fail to respond. We aim to assess baseline factors for association with long-term survival from durvalumab treatment in patients with recurrent/metastatic head and neck squamous cell carcinoma (HNSCC)1,2. Methods: Pooled longitudinal tumor size, survival, and dropout data from four trials (1108: NCT01693562, CONDOR: NCT02319044 , HAWK: NCT02207530, and EAGLE: NCT02369874) involving 467 HNSCC patients were used to develop tumor size-driven hazard models. A panel of 66 serum protein biomarkers at baseline and 4 relevant clinical markers from 346 out of 413 patients treated with durvalumab (all studies except 1108) were initially screened to select a pool of 21 candidate covariates. The criteria for dimensionality reduction comprised correlation strength between biomarkers and pharmacological hypotheses pertaining to a prior analysis3 (inflammation, immunomodulation, tumor burden and angiogenesis). Results: The final tumor model highlighted that high tumor burden, elevated LDH and neutrophil-lymphocyte ratio were associated with faster tumor growth while patients with lower baseline tumor burden had an increase in net tumor shrinkage. For overall survival, the model suggested that high levels of immunomodulators (IL23, Osteocalcin), low inflammation (IL6, NLR), low tumor burden, and low angiogenesis factors (von Willebrand factor (vWF), plasminogen activator inhibitor-1 (PAI-1)) were associated with survival benefits for patients treated with durvalumab. Specifically, these patients had baseline serum IL23 > 2.1 pg/mL and Osteocalcin > 32 pg/mL or serum PAI-1 < 229 pg/mL and serum IL6 < 5.4 pg/mL which corresponded to a hazard ratio estimate (HR and 95%CI) of 0.36 (0.27- 0.47), logrank p-value: 2.3x10−14. The median (n, 95%CI) overall survival time for the patients with favorable biomarker profile was 14.6 months (n = 129, 11.2-21.4) vs. 4.4 months (n = 217, 3.6-5.3). Conclusions: Our results corroborate the prior hypothesis highlighting the prognostic value of inflammation, disease burden, tumor angiogenesis, and immunomodulatory factors on the clinical outcomes of HNSCC patients treated with durvalumab3. Collectively, we identified a serum biomarker profile of HNSCC patients with median survival times exceeding 1 year which may potentially be used for patient enrichment following further validation in prospective studies. References: 1Yanan CPT 2017, 2Baverel, 2018 ENA, 3Guo, X, 2019 Asco P6048 Clinical trial information: NCT01693562, NCT02319044, NCT02207530, NCT02369874 .

A QSP Model for Predicting Clinical Responses to Monotherapy, Combination and Sequential Therapy Following CTLA-4, PD-1, and PD-L1 Checkpoint Blockade

Over the past decade, several immunotherapies have been approved for the treatment of melanoma. The most prominent of these are the immune checkpoint inhibitors, which are antibodies that block the inhibitory effects on the immune system by checkpoint receptors, such as CTLA-4, PD-1 and PD-L1. Preclinically, blocking these receptors has led to increased activation and proliferation of effector cells following stimulation and antigen recognition, and subsequently, more effective elimination of cancer cells. Translation from preclinical to clinical outcomes in solid tumors has shown the existence of a wide diversity of individual patient responses, linked to several patient-specific parameters. We developed a quantitative systems pharmacology (QSP) model that looks at the mentioned checkpoint blockade therapies administered as mono-, combo- and sequential therapies, to show how different combinations of specific patient parameters defined within physiological ranges distinguish different types of virtual patient responders to these therapies for melanoma. Further validation by fitting and subsequent simulations of virtual clinical trials mimicking actual patient trials demonstrated that the model can capture a wide variety of tumor dynamics that are observed in the clinic and can predict median clinical responses. Our aim here is to present a QSP model for combination immunotherapy specific to melanoma.

Abstract 3158: Prediction of overall survival in urothelial cancer patients using tumor sizes and baseline risk factors: longitudinal modeling approach for durvalumab and durvalumab + tremelimumab

Background: Durvalumab [D] is a human mAb that binds to PD-L1 and blocks its interaction with PD-1 and CD80. Tremelimumab [T] blocks the inhibitory effects of CTLA-4, and therefore enhances T-cell activation. The objectives of this analysis were to develop a model linking overall survival (OS) to baseline risk factors and changes in tumor size during treatment to identify key factors impacting response to D or D +T.

Methods: The analysis dataset included UC patients from two clinical trials: Study 1108 (D 10 mg/kg Q2W; n=201) and Study 10 (D 20 mg/kg Q4W + T 1 mg/kg Q4W for 4 doses, followed by D 20 mg/kg Q4W alone; n=168). Longitudinal tumor size data were analyzed using a nonlinear mixed effect model with key parameters describing tumor growth, tumor killing, and delay in immune response. Subsequently, a parametric survival model was developed to link baseline risk factors and predicted percent change in tumor size at week 8 to OS.

Results: Tumor kinetic model adequately described the longitudinal tumor size data from UC patients. Baseline tumor size (p&lt;0.01) and PD-L1 status (p&lt;0.01) were identified as significant covariates for tumor killing rate. The most influential factor associated with faster tumor growth was liver metastasis (p&lt;0.01), while higher hemoglobin levels (p&lt;0.01) were associated with decreased tumor growth rate. Based on parametric survival modeling, liver metastasis (~34% decrease in OS, p&lt;0.0001), albumin (~ 1-fold increase in OS per 1g/dL increase, p&lt;0.0001), and percent change in tumor size at week 8 (~52% increase in OS with 30% tumor shrinkage at week 8, p&lt;0.0001) were found to be significant and clinically relevant predictors of OS.

Conclusions: The parametric survival model coupled with tumor kinetic model adequately described clinical outcomes in UC patients treated with D or D+T and enabled identification of key factors potentially impacting response to immune therapy in UC. This approach can be a useful tool for guiding patient selection/enrichment strategies and optimizing trial designs for immuno-oncology (IO) therapies. Further validation and prospective evaluation of this model may be conducted in other IO trials.

Citation Format: Mei Tang, Yu Jiang, Han Si, Yanan Zheng, Chen Gao, Guozhi Gao, Natasha Angra, Shaad Abdullah, Brandon Higgs, Lorin Roskos, Rajesh Narwal. Prediction of overall survival in urothelial cancer patients using tumor sizes and baseline risk factors: longitudinal modeling approach for durvalumab and durvalumab + tremelimumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3158.

Prognostic Significance of Liver Metastasis in Durvalumab-Treated Lung Cancer Patients

INTRODUCTION

Two clinical studies (Study 1108 and ATLANTIC) were analyzed to evaluate the prognostic value of baseline liver metastases (LMs) in advanced/metastatic non-small-cell lung cancer patients treated with durvalumab 10 mg/kg every 2 weeks.

PATIENTS AND METHODS

A multivariate Cox proportional hazards analysis was conducted; covariates included performance status, tumor stage, histology, sex, age, smoking status, and programmed cell death ligand 1 (PD-L1) status.

RESULTS

In all, 569 patients were included. LMs were present in 31.6% (96/304) of Study 1108 patients and 17.9% (47/263) of ATLANTIC patients. Median overall survival (OS) was shorter in patients with LMs than in those without in both studies. In both studies, LMs were an independent negative prognostic factor for OS and progression-free survival. Objective response rates were also significantly lower. PD-L1 independently predicted benefit across all patients.

CONCLUSION

Liver metastases were associated with worse outcomes irrespective of PD-L1 status, but PD-L1 status predicted benefit from durvalumab irrespective of LMs.

A Computational Model of Neoadjuvant PD-1 Inhibition in Non-Small Cell Lung Cancer

Immunotherapy and immune checkpoint blocking antibodies such as anti-PD-1 are approved and significantly improve the survival of advanced non-small cell lung cancer (NSCLC) patients, but there has been little success in identifying biomarkers capable of separating the responders from non-responders before the onset of the therapy. In this study, we developed a quantitative system pharmacology (QSP) model to represent the anti-tumor immune response in human NSCLC that integrated our knowledge of tumor growth, antigen processing and presentation, T cell activation and distribution, antibody pharmacokinetics, and immune checkpoint dynamics. The model was calibrated with the available data and was used to identify potential biomarkers as well as patient-specific response based on the patient parameters. The model predicted that in addition to tumor mutational burden (TMB), a known biomarker for anti-PD-1 therapy in NSCLC, the number of effector T cells and regulatory T cells in the tumor and blood is a predictor of the responders. Furthermore, the model simulated a set of 12 patients with known TMB and MHC/antigen-binding affinity from a recent clinical trial (ClinicalTrials.gov number, NCT02259621) on neoadjuvant nivolumab therapy in resectable lung cancer and predicted an augmented durable response in patients with adjuvant nivolumab treatment in addition to the clinical trial protocol of neoadjuvant nivolumab treatment followed by resection. Overall, the model provides a valuable framework to model tumor immunity and response to immune checkpoint blockers to enhance biomarker discovery and performing virtual clinical trials to aid in design and interpretation of the current trials with fewer patients.

Detecting bliss synergy in in vivo combination studies with a tumor kinetic model

Linear models are generally reliable methods for analyzing tumor growth in vivo, with drug effectiveness being represented by the steepness of the regression slope. With immunotherapy, however, not all tumor growth follows a linear pattern, even after log transformation. Tumor kinetics models are mechanistic models that describe tumor proliferation and tumor killing macroscopically, through a set of differential equations. In drug combination studies, although an additional drug-drug interaction term can be added to such models, however, the drug interactions suggested by tumor kinetics models cannot be translated directly into synergistic effects. We have developed a novel statistical approach that simultaneously models tumor growth in control, monotherapy, and combination therapy groups. This approach makes it possible to test for synergistic effects directly and to compare such effects among different studies.

In silico simulation of a clinical trial with anti-CTLA-4 and anti-PD-L1 immunotherapies in metastatic breast cancer using a systems pharmacology model

The low response rate of immune checkpoint blockade in breast cancer has highlighted the need for predictive biomarkers to identify responders. While a number of clinical trials are ongoing, testing all possible combinations is not feasible. In this study, a quantitative systems pharmacology model is built to integrate immune-cancer cell interactions in patients with breast cancer, including central, peripheral, tumour-draining lymph node (TDLN) and tumour compartments. The model can describe the immune suppression and evasion in both TDLN and the tumour microenvironment due to checkpoint expression, and mimic the tumour response to checkpoint blockade therapy. We investigate the relationship between the tumour response to checkpoint blockade therapy and composite tumour burden, PD-L1 expression and antigen intensity, including their individual and combined effects on the immune system, using model-based simulations. The proposed model demonstrates the potential to make predictions of tumour response of individual patients given sufficient clinical measurements, and provides a platform that can be further adapted to other types of immunotherapy and their combination with molecular-targeted therapies. The patient predictions demonstrate how this systems pharmacology model can be used to individualize immunotherapy treatments. When appropriately validated, these approaches may contribute to optimization of breast cancer treatment.

Exposure-Response Analysis of Overall Survival for Tremelimumab in Unresectable Malignant Mesothelioma: The Confounding Effect of Disease Status

Tremelimumab, an anti‐cytotoxic T‐lymphocyte antigen‐4 monoclonal antibody that enhances T‐cell activation, was evaluated in a randomized, double‐blind, placebo‐controlled, phase IIb study (NCT01843374) in patients with unresectable malignant mesothelioma. The study demonstrated no clinically meaningful differences in overall survival (OS). The objective of this analysis was to evaluate the relationship of exposure with OS. A population pharmacokinetic (PK) model adequately described the PK data. Three factors (sex, C‐reactive protein, and baseline tumor size) were identified as statistically significant PK predictors (P < 0.05 on clearance). A positive association between exposure and OS was observed. However, an association between key baseline factors with OS (regardless of treatment) and imbalances in prognostic factors favoring patients with higher exposure (upper vs. lower PK quartile) was seen. Taken together, these results suggest that the exposure OS relationship observed for tremelimumab in mesothelioma is likely spurious rather than a true association of exposure with efficacy.

MEDI3039, a novel highly potent tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptor 2 agonist, causes regression of orthotopic tumors and inhibits outgrowth of metastatic triple-negative breast cancer

Background

TNF-related apoptosis-inducing ligand (TRAIL) receptor agonists are attractive anti-tumor agents because of their capability to induce apoptosis in cancer cells by activating death receptors (DR) 4 and 5 with little toxicity against normal cells. Despite an attractive mechanism of action, previous clinical efforts to use TRAIL receptor agonists have been unsuccessful. In this study, we examined MEDI3039, a highly potent multivalent DR5 agonist, in breast cancer cell lines and in vivo models.

Methods

As in vitro model systems, we used 19 breast cancer cell lines that are categorized into four subtypes: ER+, HER2 amplified, basal A (triple-negative breast cancer) TNBC, and basal B TNBC. Cell viability was analyzed by MTS and RealTime live/dead assays. As in vivo model systems, MDA-MB231T orthotopic primary tumor growth in the mammary fat pad (MFP) and two experimental lung metastasis models were used. The effect of MEDI3039 on MFP tumors was assessed with immunohistochemical analysis. Lung metastases were analyzed with Bouin’s and H&E staining.

Results

MEDI3039 killed multiple breast cancer cell lines, but the sensitivity varied among different subtypes. Sensitivity was basal B TNBC >> basal A TNBC > HER2 amplified > ER+ (average IC₅₀ = 1.4, 203, 314, 403 pM, respectively). While the pattern of relative sensitivity was similar to GST-TRAIL in most cell lines, MEDI3039 was at least two orders of magnitude more potent compared with GST-TRAIL. In the MFP model, weekly treatment with 0.1 or 0.3 mg/kg MEDI3039 for 5 weeks inhibited tumor growth by 99.05% or 100% (median), respectively, compared with the control group, and extended animal survival (p = 0.08 or p = 0.0032 at 0.1 or 0.3 mg/kg, respectively). MEDI3039-induced caspase activation was confirmed in tumors grown in MFP (p < 0.05). In an experimental pulmonary metastasis model, MEDI3039 significantly suppressed outgrowth of surface (p < 0.0001) and microscopic metastases (p < 0.05). In an established lung metastasis model, MEDI3039 significantly inhibited growth of metastases (p < 0.01 in surface [> 4 mm], p < 0.01 in tumor percentage) and extended animal survival (p < 0.0001).

Conclusion

MEDI3039 is a potent DR5 agonist in breast cancer cells in vitro and in vivo and has potential as a cancer drug in breast cancer patients, especially those with basal B TNBC.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1116-1) contains supplementary material, which is available to authorized users.

Sustainable Development Goals: Leveraging the Global Agenda for Driving Health Policy Reforms and Achieving Universal Health Coverage in India

Universal Health Coverage (UHC) is now the critical yardstick for countries to measure and track progress toward the "Sustainable Development Goals (SDGs)." Being a signatory, India has started taking measures to attain the targets laid out within the SDG framework and achieving the UHC. With India's National Health Policy (NHP) - 2017 in place, the policy environment for transforming country's health landscape coincides with that of the global approach toward strengthening of health systems and achieving UHC. It is imperative that for achieving the desired outcomes laid down in the SDGs and NHP-2017, coordinated actions are required including political action for making health an individual's right; effective stewardship from the National Ministry of Health and Family Welfare; reorganization of health-care service delivery implementing a "systems approach;" ensuring financial protection against health-care costs; and enhancing community participation and accountability. Undertaking these steps, imbibing the learning, and dwelling upon global experiences can help the country strongly move forward towards achieving global and national targets, thereby ensuring UHC for all its citizens.

A computational multiscale agent-based model for simulating spatio-temporal tumour immune response to PD1 and PDL1 inhibition

When the immune system responds to tumour development, patterns of immune infiltrates emerge, highlighted by the expression of immune checkpoint-related molecules such as PDL1 on the surface of cancer cells. Such spatial heterogeneity carries information on intrinsic characteristics of the tumour lesion for individual patients, and thus is a potential source for biomarkers for anti-tumour therapeutics. We developed a systems biology multiscale agent-based model to capture the interactions between immune cells and cancer cells, and analysed the emergent global behaviour during tumour development and immunotherapy. Using this model, we are able to reproduce temporal dynamics of cytotoxic T cells and cancer cells during tumour progression, as well as three-dimensional spatial distributions of these cells. By varying the characteristics of the neoantigen profile of individual patients, such as mutational burden and antigen strength, a spectrum of pretreatment spatial patterns of PDL1 expression is generated in our simulations, resembling immuno-architectures obtained via immunohistochemistry from patient biopsies. By correlating these spatial characteristics with in silico treatment results using immune checkpoint inhibitors, the model provides a framework for use to predict treatment/biomarker combinations in different cancer types based on cancer-specific experimental data.

Population Pharmacokinetics of Durvalumab in Cancer Patients and Association With Longitudinal Biomarkers of Disease Status

The objectives of this analysis were to develop a population pharmacokinetics (PK) model of durvalumab, an anti-PD-L1 antibody, and quantify the impact of baseline and time-varying patient/disease characteristics on PK. Pooled data from two studies (1,409 patients providing 7,407 PK samples) were analyzed with nonlinear mixed effects modeling. Durvalumab PK was best described by a two-compartment model with both linear and nonlinear clearances. Three candidate models were evaluated: a time-invariant clearance (CL) model, an empirical time-varying CL model, and a semimechanistic time-varying CL model incorporating longitudinal covariates related to disease status (tumor shrinkage and albumin). The data supported a slight decrease in durvalumab clearance with time and suggested that it may be associated with a decrease in nonspecific protein catabolic rate among cancer patients who benefit from therapy. No covariates were clinically relevant, indicating no need for dose adjustment. Simulations indicated similar overall PK exposures following weight-based and flat-dosing regimens.

Population Modeling of Tumor Kinetics and Overall Survival to Identify Prognostic and Predictive Biomarkers of Efficacy for Durvalumab in Patients With Urothelial Carcinoma

Durvalumab is an anti‐PD‐L1 monoclonal antibody approved for patients with locally advanced or metastatic urothelial carcinoma (UC) that has progressed after platinum‐containing chemotherapy. A population tumor kinetic model, coupled with dropout and survival models, was developed to describe longitudinal tumor size data and predict overall survival in UC patients treated with durvalumab (NCT01693562) and to identify prognostic and predictive biomarkers of clinical outcomes. Model‐based covariate analysis identified liver metastasis as the most influential factor for tumor growth and immune‐cell PD‐L1 expression and baseline tumor burden as predictive factors for tumor killing. Tumor or immune‐cell PD‐L1 expression, liver metastasis, baseline hemoglobin, and albumin levels were identified as significant covariates for overall survival. These model simulations provided further insights into the impact of PD‐L1 cutoff values on treatment outcomes. The modeling framework can be a useful tool to guide patient selection and enrichment strategies for immunotherapies across various cancer indications.

Abstract 4531: Systems pharmacology to predict cellular biomarkers and optimize mono- and combination-therapy regimens: Focusing on immune checkpoint targets PD-1, PD-L1 and CTLA-4

Cancer immunotherapy focuses on stimulating and promoting the immune system to recognize and eliminate cancer cells, with several FDA approvals in recent years. However, identifying patients best suited for specific immune therapies, and determining optimal treatment regimens continue to be a clinical challenge. Using a molecular-detailed computational systems pharmacology model to identify cellular biomarkers and optimize regimens, we may be able to predict the efficacy of regimens in specific patient populations, and expedite drug development for cancer treatment. We developed a cell/receptor-based multi-compartment systems pharmacology model focusing on the immune response against a growing tumor, with the intent to test the effects of immune checkpoint inhibitors against PD-1, PD-L1 and CTLA-4 administered as mono- and combination therapies. Additionally, the model also allows for testing of other immuno-therapies, such as adoptive cell therapies, which can be combined with the checkpoint inhibitors. The model was designed and developed using the SimBiology plug-in in MATLAB. Simulations were performed with parameters that define the immune response at particular tumor stages of melanoma and NSCLC. All results were qualitatively and quantitatively compared to experimental pre-clinical and clinical data for model validation, or used for the generation of predictions suitable for further experimental testing. In silico, we have identified that administrations of the prescribed doses of 1-10 mg/kg of anti-CLTA-4 (based on binding kinetics) effectively saturates the receptors on the T cells, and promotes both an extended life span of the antigen presenting cells (APCs), and the maximum attainable activation levels of the effector T cells. The model further predicts that the effectiveness of anti-CTLA-4 therapy is limited by the immunogenicity of the system (i.e., the antigen intensity level and number of APCs presenting the antigens) in a monotonic fashion. Furthermore, injecting activated APCs without therapy would show a temporary tumor response and a subsequent recovery by the tumor to its original growth trajectory, while raising the antigen intensity had a sustained effect on tumor response. Other simulations indicate that, despite the lack of apparent tumor response, a sustained immune attack may be ongoing in the body; however, the immune activity is proportionally limited by the tumor and regulatory cells. Lastly, several dose-responses and clinical trials were simulated for both combination and monotherapies, and correlated with published clinical trial data. Future work will focus on uncovering the cellular biomarkers responsible for such results, experimentally validating them, as well as simulating optimal combination treatment regimens for future evaluation.

Citation Format: Oleg Milberg, Chang Gong, Bing Wang, Paolo Vicini, Rajesh Narwal, Lorin Roskos, Aleksander Popel. Systems pharmacology to predict cellular biomarkers and optimize mono- and combination-therapy regimens: Focusing on immune checkpoint targets PD-1, PD-L1 and CTLA-4 [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 4531. doi:10.1158/1538-7445.AM2017-4531

Abstract 5045: Pharmacokinetics and pharmacodynamics of MEDI0680, a fully human anti-PD1 monoclonal antibody, in patients with advanced malignancies

Background: MEDI0680 (AMP-514) is a humanized immunoglobulin gamma 4, kappa (IgG4κ) monoclonal antibody (mAb) specific for human programmed cell death-1 (PD-1), developed for the treatment of cancer. The primary objectives of this analysis were to (a) describe the pharmacokinetics (PK) of MEDI0680 and quantitate the impact of patient/disease characteristics on PK variability (b) to compare body weight (WT)-based and fixed dosing regimens of MEDI0680 and (c) to characterize PK-pharmacodynamic (receptor occupancy) relationship.

Methods: A total of 905 serum concentration records from 58 patients in Phase 1 study (D6020C00002) designed to evaluate safety, tolerability and PK following 0.1, 0.5, 2.5, 10, and 20 mg/kg every 3 weeks (Q3W), every 2 weeks (Q2W) or weekly doses (QW) as intravenous (IV) infusion of MEDI0680 were included in this analysis. The population PK analysis was performed using a non-linear mixed effects modeling approach in NONMEM (version 7.2) software. Impact of patient demographics, clinical indices and biomarkers on PK parameters were explored. The appropriateness of the final model was tested using visual predictive check (VPC). A sequential PK-PD analysis was performed using receptor occupancy (RO) data from 35 subjects.

Results: MEDI0680 PK profiles were best described using a 2-compartment model with linear clearance. The clearance (CL), volume of distribution (Vc) were 0.27 L/day, 5.07 L with a modest between-subject variability of 30% and 19%, respectively. None of the evaluated covariates showed any impact on PK parameters except a minor (not clinically relevant) impact of body weight on volume of distribution. VPC results demonstrated good predictability of the final population PK model. A direct Emax model described the PK-PD relationship of MEDI0680. The estimate of EC50 was approximately 9.3 µg/mL. PK/PD simulations indicate that following 20 mg/kg Q2W dose, &gt;90% receptor occupancy can be maintained in all subjects. Based on preclinical/clinical PK, PD, and safety data, a dose of 20 mg/kg Q2W was selected for phase 2 studies.

Conclusions: A population PK model of MEDI0680 was developed and validated. Modeling results indicate no need for dose adjustment based on patient/disease characteristics. Similar PK is expected following both WT-based and fixed dosing regimens. PK/PD findings support the dose of 20 mg/kg Q2W. Clinical studies are ongoing in various tumor types.

Citation Format: Xuyang Song, Xizhe Gao, Bo Zheng, Chelsea Black, Matthew Gribbin, Joyson Karakunnel, Lorin Roskos, Rajesh Narwal. Pharmacokinetics and pharmacodynamics of MEDI0680, a fully human anti-PD1 monoclonal antibody, in patients with advanced malignancies [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 5045. doi:10.1158/1538-7445.AM2017-5045

Abstract 5046: Exposure-efficacy (OS) analysis of tremelimumab in unresectable malignant mesothelioma

Purpose: Tremelimumab is a fully human anti-CTLA-4 IgG2 monoclonal antibody that enhances human T-cell activation. Tremelimumab was evaluated in a Phase IIb (DETERMINE), randomised, double-blind, placebo-controlled study in patients with unresectable pleural or peritoneal malignant mesothelioma, randomised (2:1) to receive either tremelimumab (10 mg/kg, seven doses Q4W followed by Q12W) or placebo. The study demonstrated no clinically meaningful differences in overall survival (OS). The primary objectives of this analysis were to evaluate the relationship of exposure with OS, and the impact of potential confounders.

Methods: A population PK model was developed to estimate and derive PK exposure metrics (area under the curve at steady state [AUCss] or clearance [CL]) for exposure-OS analysis. Impact of potential confounders was evaluated using graphical and exploratory approaches. Factors including body weight, age, gender, race, ECOG status, anatomical site (pleural or peritoneal), line of therapy, EORTC status, tumour histology, baseline tumour size, LDH, and CRP were evaluated. The analyses were performed using NONMEM 7.2 and R software.

Results: The population PK included 376 patients and 1328 post-first dose PK concentrations. PK was consistent with previous knowledge and low incidence of anti-drug antibodies was observed. A 2-compartment linear PK model adequately described the data. Tremelimumab CL and volume of distribution (V1) were 310 mL/day and 3.85 L, with moderate variability of ~38% and ~32%, respectively. There was an apparent exposure-OS relation when stratified by AUCss. However, at least 3 factors (gender, CRP, and baseline tumour size) were statistically significant PK predictors (p&lt;0.05 on CL) indicating multi-dimensional confounding effect. Higher baseline tumor size, higher CRP levels and males were associated with lower PK exposure of tremelimumab.

Conclusions: The observed apparent exposure-OS relationship is the result of imbalance in prognostic factors impacting OS rather than a true association of exposure with efficacy.

Citation Format: Paul Baverel, Lorin Roskos, Manasa Tatipalli, Nancy Lee, Paul Stockman, Maria Taboada, Paolo Vicini, Kevin Horgan, Rajesh Narwal. Exposure-efficacy (OS) analysis of tremelimumab in unresectable malignant mesothelioma [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 5046. doi:10.1158/1538-7445.AM2017-5046

Association of liver metastases (LM) with survival in NSCLC patients treated with durvalumab (D) in two independent clinical trials

3038

Background: Immunotherapies have improved survival in NSCLC but not all pts benefit. Besides baseline PDL1 expression, routinely measured clinical factors may predict clinical outcomes in immunotherapy trials. LM are associated with poor prognosis in melanoma and bladder cancer pts treated with anti-PD1/L1, respectively. We examined correlation between pretreatment LM and survival in D-treated NSCLC pts. Methods: CP1108/NCT01693562 and ATLANTIC/NCT02087423 were nonrandomized phase 1/2 and 2 trials, respectively, of D 10 mg/kg Q2W in advanced NSCLC. As of Oct 24/Jun 3 2016, 304/265 primarily pretreated pts were enrolled in CP1108/ATLANTIC Cohort 2. Cox proportional hazards analysis was conducted, first among LM+/− pts, then LM+/− and PDL1 high/low pts. Both models accounted for tumor stage, ECOG/WHO PS, histology, sex, age, smoking and PDL1 status. PDL1 high was defined as ≥25% tumor cells immunostained for PDL1 at any intensity. Results: LM absence was a positive independent predictor of OS and PFS in both trials. LM− and PDL1 high or low pts had improved OS and PFS vs PDL1 low/LM+; PDL1 high/LM+ pts had improved PFS vs PDL1 low/LM+. An independent tumor kinetic model indicated LM as a predictive covariate of rapid tumor growth in D-treated pts. Conclusions: LM are associated with shorter survival in D-treated NSCLC pts in 2 trials irrespective of PDL1 status. Clinical trial information: NCT02087423 and NCT01693562. [Table: see text]

Exposure-efficacy and safety analysis of durvalumab in patients with urothelial carcinoma (UC) and other solid tumors

2568

Background: Durvalumab is a human monoclonal antibody that binds to PD-L1 and blocks its interaction with PD-1 and CD-80. The objective of this analysis was to evaluate the relationship between durvalumab PK exposure with efficacy and safety following 10 mg/kg Q2W durvalumab. Methods: Data from Study 1108 (Phase 1/2; all tumor types) and ATLANTIC (Phase 2; NSCLC) were used for exposure-safety analysis for Study 1108 UC cohort, Study 1108 all patients and ATLANTIC patients, respectively, whereas the exposure-efficacy analysis was performed using data from Study 1108 UC cohort. The observed PK exposure metrics included PK concentrations after the first, second or steady state doses. Efficacy endpoints used were objective response rate (ORR) and best percentage change in target lesion from baseline per BICR assessment. Safety endpoints included Grade 3+ AE (any AE, drug-related AE, AESI, and drug-related AESI) and AE leading to treatment discontinuation. Results: Overall, no association of PK exposure with efficacy or safety was observed. Distribution of PK metrics were similar between responders and non-responders. The probability of objective response was similar in all quartiles of exposure (p-value ranged from 0.37 to 0.67; n = 96) with no obvious trends between PK exposures and change in tumor size. For Grade 3+ AE (all types) and AE leading to treatment discontinuation, higher PK exposure was not associated with an increased risk of AE (p-value ranged from < 0.00005 to 0.88; n = 158, 929 and 434 for 1108 UC cohort, 1108 all patients and ATLANTIC all patients, respectively). A few inverse trends were observed, likely due to confounding effect of ECOG or albumin since covariate analysis demonstrated that both variables correlated with PK and AEs. In addition, the association of ECOG and albumin versus PK exposure were also observed in the population PK modeling. Conclusions: The exposure-efficacy and exposure-safety analyses suggested that 10 mg/kg IV Q2W regimen was an appropriate dose for durvalumab as single agent in UC patients. Overall, no relationship of PK exposure with either the efficacy or safety was observed following 10 mg/kg IV Q2W regimen. Clinical trial information: NCT02087423 and NCT01693562.

Tumor shrinkage and increased overall survival are associated with improved albumin, neutrophil lymphocyte ratio (NLR) and decreased durvalumab clearance in NSCLC and UC patients receiving durvalumab

3035

Background: Progression of cancer is often associated with biomarkers of cancer inflammation, cachexia, and increased protein catabolism. Anti-PD1 and PD-L1 therapy have demonstrated durable responses across a number of tumor types. Durvalumab is a human monoclonal antibody that binds to PD-L1 and blocks its interaction with PD-1 and CD80. The primary objective of this analysis was to prospectively assess potential correlations of longitudinal changes in ALB and NLR and durvalumab clearance (CL) rate to maximum decrease in tumor size and overall survival (OS) in patients (pts) with NSCLC and UC receiving durvalumab. Methods: Longitudinal target lesion size, serum chemistry, hematology and pharmacokinetic data were obtained from 3L+ NSCLC pts (n = 418) in study ATLANTIC and 2L+ UC pts (n = 182) in study 1108 during durvalumab treatment. Nonparametric correlations (Spearman’s rho) were evaluated between OS, maximum percent change in target lesion size, and the maximum percent change from baseline observed in ALB, NLR, and CL. Results: In NSCLC, maximum decrease in tumor size was correlated with increased ALB (r = 0.46, p < 0.0001), decreased NLR (r = 0.44, p < 0.0001), and decreased CL (r = 0.66, p < 0.0001). OS was similarly correlated with increased ALB (r = 0.47, p < 0.0001), decreased NLR (r = 0.41, p < 0.0001), and decreased CL (r = 0.76, p < 0.0001). In UC, decreased tumor size also correlated with increased ALB (r = 0.43, p < 0.0001), decreased NLR (r = 0.38, p < 0.0001), and decreased CL (r = 0.65, p < 0.0001). OS in UC also correlated with increased ALB (r = 0.50, p < 0.0001), decreased NLR (r = 0.33, p < 0.0001) and decreased CL (r = 0.82, p < 0.0001). Conclusions: In NSCLC and UC pts receiving durvalumab, tumor shrinkage and longer survival are associated with increased ALB, decreased NLR and decreased clearance of durvalumab. These findings support the hypothesis that durvalumab may be associated with a decrease in protein catabolism, inflammation and cachexia among pts who benefited from therapy. Additional biomarkers of cancer, inflammation and cachexia will be evaluated for relationships to clinical outcomes.

Tumor kinetic modeling and identification of predictive factors for tumor response to durvalumab in patients with non-small cell lung cancer (NSCLC)

11555

Background: Durvalumab is a human monoclonal antibody that binds to PD-L1 and blocks its interaction with PD-1 and CD80. The primary objectives of this analysis were to describe the longitudinal tumor size profiles and identify the key factors predicting tumor growth and regression following durvalumab. Methods: Longitudinal tumor size data obtained from NSCLC patients in study 1108 (all lines of therapy) and ATLANTIC (third line and beyond) following durvalumab treatment were modeled using nonlinear mixed effect modeling. Tumor kinetics were described by four key parameters: tumor growth and killing rate constants, fraction of durvalumab-sensitive tumor cells, and delay time for tumor killing. Potential predictive factors for tumor growth and regression were evaluated in a multi-variable covariate analysis. The model was used to simulate response rates at different tumor PD-L1 expression cutoffs. Results: Tumor kinetic modeling accurately described the longitudinal tumor response profiles from NSCLC patients in both studies. The factors associated with more rapid tumor growth were liver metastases, ECOG score > 0, high neutrophil-to-lymphocyte ratio and EGFR/ALK mutation. Tumor cell PD-L1 expression, baseline tumor size and smoking history were identified as significant predictive factors for tumor killing or the fraction of sensitive tumor cells. Simulations using the tumor kinetic model showed increased response rates in patients with higher tumor cell PD-L1 expression (increased by 9-11% and 10-14% with 25% and 50% cutoff, respectively), patients receiving durvalumab as first-line therapy (increased by 12% vs. 2nd line/above), and patients with smoking histories (increased by 4-5% vs. non-smokers). Conclusions: Tumor kinetic modeling identified factors that predict tumor progression and response following durvalumab in NSCLC patients. The multivariate analysis accounts for various predictive factors within predictive biomarker strata, allowing better interpretation of different biomarker cutoffs. The modeling technique can potentially guide patient selection/enrichment, clinical trial design strategies and tumor biology. Clinical trial information: NCT02087423 and NCT01693562.

Population pharmacokinetics of durvalumab and fixed dosing regimens in patients with advanced solid tumors

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Background: Durvalumab is a human monoclonal antibody that binds to PD-L1 and blocks its interaction with PD-1 and CD80. The objectives of this analysis were to develop a population pharmacokinetics (PK) model of durvalumab, to quantitate the effect of patient/disease characteristics on PK, and to compare weight (WT)-based versus fixed dosing regimens. Methods: Data were pooled from two studies: Study 1108 (Phase 1/2; various tumor types) and ATLANTIC (Phase 2; NSCLC). A total of 1324 patients provided data following 0.1 to 20 mg/kg IV durvalumab. The population PK was performed using a non-linear mixed effects modeling approach in NONMEM software. The impact of demographics, clinical indices, and biomarkers on PK was explored. Results: Durvalumab PK was best described using a 2-compartment model with both linear and non-linear clearances. The mean (between-patient variability) linear clearance (CL) and central volume of distribution (V1) were 226 mL/day (~29%) and 3.51 L (~21%), respectively. Although population PK analysis identified a few statistically significant covariates (WT, sex, CrCL, post-baseline ADA, ECOG performance status, LDH, sPDL1 levels, tumor type, and albumin), none were found to be clinically relevant (effect on PK parameters < 30%), indicating no need for dose adjustment. Simulations indicated similar overall PK exposures following WT-based (10 mg/kg Q2W) and fixed dosing regimens (1500 mg Q4W or 750 mg Q2W); with all regimens expected to maintain target trough exposure of ~50 µg/mL in ≥95% patients. In a post-hoc analysis, durvalumab clearance was found to decrease slightly over time, with a mean maximal reduction from baseline value of 15.5%. The decrease in CL was associated with tumor shrinkage, decreased LDH, increased albumin and decreased neutrophil to lymphocyte ratio. The small decrease in CL was not considered relevant to PK exposure or dosing. Conclusions: A population PK model of durvalumab was developed and validated. No dose adjustments were needed based on any patient or disease characteristics. The analysis demonstrated the feasibility of switching to a fixed dose regimen. Clinical trial information: NCT02087423 and NCT01693562.

Development of Immunoassays for the Quantitative Assessment of Amyloid-β in the Presence of Therapeutic Antibody: Application to Pre-Clinical Studies

Utilizing decision making biomarkers in drug development requires thorough assay validation. Special considerations need to be taken into account when monitoring biomarkers using immunoassays in the presence of therapeutic antibodies. We have developed robust and sensitive assays to assess target engagement and proof of mechanism to support the clinical progression of a human monoclonal antibody against the neurotoxic amyloid-β (Aβ)₄₂ peptide. Here we present the introduction of novel pre-treatment steps to ensure drug-tolerant immunoassays and describe the validation of the complete experimental procedures to measure total Aβ₄₂ concentration (bound and unbound) in cerebrospinal fluid (CSF) and plasma, free Aβ₄₂ concentration (unbound) in CSF, and Aβ₄₀ concentration in CSF. The difference in composition of the matrices (CSF and plasma) and antigen levels therein, in combination with the hydrophobic properties of Aβ protein, adds to the complexity of validation. Monitoring pharmacodynamics of an Aβ₄₂ specific monoclonal antibody in a non-human primate toxicology study using these assays, we demonstrated a 1500-fold and a 3000-fold increase in total Aβ₄₂ in plasma, a 4-fold and 8-fold increase in total Aβ₄₂ in CSF together with a 95% and 96% reduction of free Aβ₄₂ in CSF following weekly intravenous injections of 10 mg/kg and 100 mg/kg, respectively. Levels of Aβ₄₀ were unchanged. The accuracy of these data is supported by previous pre-clinical studies as well as predictive pharmacokinetic/pharmacodynamics modeling. In contrast, when analyzing the same non-human primate samples excluding the pre-treatment steps, we were not able to distinguish between free and total Aβ₄₂. Our data clearly demonstrate the importance of thorough evaluation of antibody interference and appropriate validation to monitor different types of biomarkers in the presence of a therapeutic antibody.

Abstract A046: Phase 2 study to evaluate the clinical efficacy and safety of MEDI4736 in patients with glioblastoma (GBM)

Background: Programmed cell death ligand-1 (PD-L1) is widely expressed on antigen presenting cells (APC) and other immune cells. PD-L1 binds two important regulatory receptors on T-cells: programmed cell death-1 (PD-1) and CD80/B7. Targeting Programmed Death-1 (PD-1) and its ligand, PD-L1, have demonstrated promising anti-tumor activity among other challenging solid tumors and growing data implicates PD-1/PD-L1 signaling as a significant contributor to immunosuppression in glioblastoma (GBM). PD-1 is expressed by many GBM infiltrating lymphocytes while PD-L1 is expressed by 61-100% of GBM tumors. Furthermore, loss of the PTEN tumor suppressor gene, which occurs in 40-50% of GBM tumors, leads to increased transcription and expression of PD-L1 in GBM. These findings indicate that PD-L1 is an attractive and important therapeutic target in GBM. MEDI4736 (M), a human IgG1κ blocking monoclonal antibody against PD-L1, represents a compelling immune-mediated anti-tumor treatment for GBM.

Methods: Phase 2, multicenter, open-label study (NCT02336165) is evaluating the clinical efficacy and safety of M in GBM patients. Eligible patients include those who are newly diagnosed with unmethylated MGMT GBM scheduled for standard radiotherapy (Cohort A); Bevacizumab-naïve patients with recurrent GBM (Cohort B); and Bevacizumab-refractory patients with recurrent GBM (Cohort C). Cohort A patients will receive M at 10 mg/kg i.v. Q2W for up to 12 months beginning with standard radiotherapy. Cohort B will receive M at 10 mg/kg i.v. Q2W for up to 12 months as monotherapy. Cohort C will receive M at 10 mg/kg i.v. Q2W for up to 12 months in combination with continued bevacizumab at 10 mg/kg Q2W. Primary endpoints include overall survival (OS) at 12 months (cohort A), progression free survival rate at 6 months (PFS-6) (cohort B) and OS-6 (cohort C). Secondary endpoints are safety/tolerability, PFS, median OS, radiographic response, and quality of life (QoL) by EORTC QLQ-C30/BN20. Exploratory endpoints are patient neurologic function using the Neurologic Assessment in Neuro-Oncology (NANO) scale, as well as immuno-correlative biomarkers and pharmacokinetics.

Cohort A represents the first time MEDI4736 is being given in combination with radiation, so a 3+3 subject safety run-in is required by protocol. Subjects must clear a 10 week DLT observation period before enrollment opens to the remainder of the cohort. If 2 or more DLTs are noted within the first 6 patients, then the MEDI4736 dose will be de-escalated. Cohort C represents the first time MEDI4736 is being given in combination with bevacizumab, so a 3+3 subject safety run-in period similar to that for Cohort A is also required, but with a 6 week DLT observation period.

Study Status: All cohorts opened to enrollment in March 2015 with Cohorts A and C currently limited by the subject safety run-in period. As of 10 June 2015, the numbers of subjects enrolled by cohort are: Cohort A = 2, Cohort B = 26, Cohort C = 3. No DLTs have been reported, and clinical efficacy and safety data collection are ongoing.

Citation Format: David A. Reardon, Jorg Dietrich, Thomas Kaley, Hui Gan, Gavin P. Dunn, Timothy Cloughesy, Michael Lim, Jennifer Clarke, Andrew Park, Linda Pan, Domenic W. Lai, Joyson Karakunnel, Paul Robbins, Rajesh Narwal, Ralph Venhaus. Phase 2 study to evaluate the clinical efficacy and safety of MEDI4736 in patients with glioblastoma (GBM). [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 A046.

Combinatorial approaches for controlling pericarp browning in Litchi (Litchi chinensis) fruit

The availability of fruit like litchi has been limited by variability in yield, alternate bearing, seasonal differences and most commonly post harvest problems. The litchi fruit has a very short shelf-life during which red color turns brown which greatly affects the appeal to consumer although not the unique flavor. This review article focuses on the post harvest problems especially browning of litchi. The pericarp of litchi is also sensitive to desiccation and turns brown and brittle once moisture is reduced to half. A large number of approaches have been tried to solve this problem starting from hydro-cooling to gamma irradiation but single approach could not suffice for all. In modern era, the logical base of controlling browning is either to control the responsible enzyme or remove the undesirable product of enzyme catalyzed reaction. Thus enzyme technology with good postharvest practice can definitely solve this problem.

Abstract LB-228: Pharmacokinetics of Tremelimumab, a fully human anti-CTLA-4 monoclonal antibody, in subjects with unresectable malignant mesothelioma

Purpose: Tremelimumab is a fully human IgG2 monoclonal antibody specific for cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4/CD152). Tremelimumab blocks the interaction of CTLA-4 with its ligands B7.1 and B7.2, and enhances human T-cell activation, as demonstrated by increased interleukin-2 production in in-vitro/in-vivo studies. The primary objectives of this analysis were to assess the preliminary population pharmacokinetics (PK) of tremelimumab in mesothelioma and identify the impact of potential patient/disease characteristics on PK variability.

Methods: Tremelimumab serum concentration-time data were collected from a second-line, single-arm phase-2 study (NCT01649024/NCT01655888) designed to evaluate clinical activity along with safety and tolerability of multiple IV doses of tremelimumab in patients with malignant mesothelioma. Two dosing regimens were tested: 15 mg/kg every 90 days (Q90D) up to 4 doses in a 12 month period until progressive disease or unacceptable toxicity and, 10 mg/kg every 4 weeks (Q4W) for 6 months followed by 10 mg/kg every 12 weeks (Q12W) until progressive disease or unacceptable toxicity. A total of 40 subjects provided evaluable PK data at various prespecified time points following both dosing regimens. Tremelimumab serum concentrations were determined using a validated enzyme-linked immunosorbent assay (ELISA) with a lower limit of quantitation (LLOQ) of 0.156 µg/mL. PK analysis was performed using a non-linear mixed effects modeling approach with NONMEM 7.2 software.

Results: Tremelimumab PK exposure in mesothelioma subjects was similar to previous melanoma studies following 15 mg/kg Q90D. Following the 15 mg/kg Q90D, PK exposure was below the target trough level of ∼30 µg/mL for about half of the dosing interval with almost all subjects below the LLOQ at the end of the 90-day dosing interval. Following more frequent dosing of 10 mg/kg Q4W, PK exposure was increased and maintained at or above the target level in the majority of subjects over the entire dosing interval. Tremelimumab PK was best described using a 2-compartment linear model with first order elimination. Following IV dosing, the typical clearance (CL) and central volume of distribution (Vc) were 0.2 L/day and 3.5 L, respectively. The between-subject variability for CL and Vc were 22% and 7%, respectively. The estimated typical PK parameters were similar to other monoclonal antibodies without target mediated elimination. The baseline body weight and Eastern Cooperative Oncology Group (ECOG) performance status were identified as significant covariates for CL, whereas only baseline body weight was significant covariate for volume of distribution.

Conclusions: A 2-compartment population PK model adequately described tremelimumab PK in subjects with mesothelioma. PK parameter estimates were similar in both mesothelioma and melanoma populations. Tremelimumab 10 mg/kg Q4W yielded higher exposure than 15 mg/kg Q90D with a majority of subjects maintaining concentrations above the target trough level of ∼30 µg/mL over the dosing interval. Preliminary covariate screening identified body weight and ECOG as influential factors for PK parameters. These correlations will be further validated using data from larger clinical trials.

Citation Format: Luana Calabro', Rajesh Narwal, Paul B. Robbins, Alessandra Di Pietro, Ornella Cutaia, Ester Fonsatti, Diego Annesi, Carolina Fazio, Ramy Ibrahim, Michele Maio. Pharmacokinetics of Tremelimumab, a fully human anti-CTLA-4 monoclonal antibody, in subjects with unresectable malignant mesothelioma. [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 LB-228. doi:10.1158/1538-7445.AM2014-LB-228

A phase I dose-escalation study of MEDI-575, a PDGFRα monoclonal antibody, in adults with advanced solid tumors

Purpose

The purpose of the study was to evaluate safety and determine the maximum tolerated dose (MTD) of MEDI-575, a fully human monoclonal antibody that selectively binds to platelet-derived growth factor receptor-α (PDGFRα), in patients with advanced solid tumors.

Methods

This phase I multicenter, open-label, single-arm study enrolled adults in a 3 + 3 dose escalation design to receive MEDI-575 (3, 6, 9, 12, or 15 mg/kg) once weekly (QW) until toxicity or disease progression occurred. One 0.5-mg/kg dose was given before the first dose in the 3-mg/kg cohort to determine pharmacokinetics (PK) and pharmacodynamics under unsaturated conditions. After completion of dose escalation in the QW cohorts, patients were enrolled in two additional cohorts and received MEDI-575 25 or 35 mg/kg every 3 weeks (Q3W). Secondary measures included assessments of PK, immunogenicity, and antitumor activity.

Results

A total of 35 patients received MEDI-575 QW (n = 23) or Q3W (n = 12). Most treatment-related adverse events were grade 1 or 2 in severity across all dose levels, with fatigue (n = 12) and nausea (n = 8) being reported most frequently. With no reports of dose-limiting toxicities (DLTs), the MTD was not reached. MEDI-575 exhibited a nonlinear PK profile and increased plasma platelet-derived growth factor-AA levels in a dose-dependent manner with limited immunogenicity. Stable disease was reported as the best tumor response in 9 of 29 evaluable patients; however, no objective responses were reported.

Conclusion

Administration of MEDI-575 QW or Q3W resulted in a favorable safety profile, including a lack of DLTs, but without evidence of antitumor activity in patients with refractory solid tumors.

Sustained peripheral depletion of amyloid-β with a novel form of neprilysin does not affect central levels of amyloid-β

Lowering levels of peripheral amyloid-β has been proposed as a strategy to reduce plaques in patients with Alzheimer’s disease. Henderson et al. test a modified version of the amyloid-degrading enzyme neprilysin in rats, monkeys and Tg2576 mice. Levels of amyloid-β were reduced in the bloodstream, but not in the CNS.

Alzheimer’s disease is characterized by the accumulation of amyloid deposits in the brain and the progressive loss of cognitive functions. Although the precise role of amyloid-β in disease progression remains somewhat controversial, many efforts to halt or reverse disease progression have focussed on reducing its synthesis or enhancing its removal. It is believed that brain and peripheral soluble amyloid-β are in equilibrium and it has previously been hypothesized that a reduction in peripheral amyloid-β can lower brain amyloid-β, thereby reducing formation of plaques predominantly composed of insoluble amyloid-β; the so-called peripheral sink hypothesis. Here we describe the use of an amyloid-β degrading enzyme, the endogenous metallopeptidase neprilysin, which is fused to albumin to extend plasma half-life and has been engineered to confer increased amyloid-β degradation activity. We used this molecule to investigate the effect of degradation of peripheral amyloid-β on amyloid-β levels in the brain and cerebrospinal fluid after repeated intravenous dosing for up to 4 months in Tg2576 transgenic mice, and 1 month in rats and monkeys. This molecule proved highly effective at degradation of amyloid-β in the periphery but did not alter brain or cerebrospinal fluid amyloid-β levels, suggesting that the peripheral sink hypothesis is not valid and is the first time that this has been demonstrated in non-human primates.

Abstract B80: A Phase II randomized, double-blind, placebo-controlled study of tremelimumab for second- and third-line treatment in patients with unresectable pleural or peritoneal mesothelioma

Malignant mesothelioma (MM) is an uncommon cancer, caused principally by asbestos exposure. No treatments after first-line platinum-pemetrexed (1) have shown survival benefit (2), thus novel approaches are needed. Asbestos exposure induces immunosuppression and immune dysfunction in the mesothelium environment mainly by hyperactivation of regulatory T lymphocytes and over-production of cytokines that inhibit cytotoxic T lymphocytes and natural killer cells (3). Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4, CD152) modulates and eventually switches off T cell activation. Tremelimumab binds to the CTLA-4 antigen, preventing its negative regulatory signaling to cytotoxic T cells (4). Results from a single arm phase 2 study of tremelimumab in 29 patients with MM who progressed on a platinum-based regimen showed promising 1- and 2- year survival rates (48.3% and 36.7%) and a safety profile consistent with previous tremelimumab studies. Two patients had durable partial response (6 and 15+ mo.): 1 after initial progressive disease. The disease control rate (DCR) was 31.0%: 5 patients had prolonged stable disease (9 to 27+ mo.). In addition, absolute levels of CD4+ICOS+ T cells significantly correlated (P = .007) with favorable overall survival (ClinicalTrials.gov # NCT01649024)(5). This study has been expanded to include an additional 29 patients who receive tremelimumab every 4 weeks for 6 doses, then every 12 weeks until confirmed disease progression. The expansion study completed enrollment in July 2013 (ClinicalTrials.gov # NCT01655888). Here we describe the design of a phase 2, randomized, double-blind, placebo-controlled study that is enrolling patients with unresectable pleural or peritoneal MM who progressed following 1 or 2 prior treatments, including a first-line platinum-pemetrexed regimen. Patients are randomized in a 2:1 ratio to receive either tremelimumab or placebo with stratification by EORTC status (low- vs high-risk), line of therapy (second vs third), and anatomical site (pleural vs peritoneal). Enrollment will include 180 patients at approximately 150 centers in multiple countries. The primary endpoint is overall survival. Secondary endpoints are durable DCR; progression-free survival (PFS); patient-reported outcomes (pain, disease-related symptoms, and time to deterioration of disease-related symptoms); duration of response and overall response rate (ORR); tremelimumab safety profile, immunogenicity, and pharmacokinetics. Exploratory endpoints are DCR, PFS, duration of response and ORR based on immune-related response criteria. Health-related quality of life, disease-related symptoms, pain, and health status in patients with durable clinical activity, as well as the association of biomarkers with tremelimumab and clinical outcomes will also be explored (ClinicalTrials.gov #NCT01843374).

This study is sponsored by MedImmune.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B80.

Citation Format: Luana Calabro, Lee M. Krug, Alessandra DiPietro, Scott Antonia, Raffit Hassan, Rajesh Narwal, Paul Robbins, Dongyue Fu, Aiman Shalabi, Hesham Abdullah, Ramy Ibrahim, Hedy Kindler, Michele Maio. A Phase II randomized, double-blind, placebo-controlled study of tremelimumab for second- and third-line treatment in patients with unresectable pleural or peritoneal mesothelioma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B80.

Has the Rate of Reduction in Infant Mortality Increased in India Since the Launch of National Rural Health Mission? Analysis of Time Trends 2000-2009 with Projection to 2015

OBJECTIVES

National Rural Health Mission (NRHM) - India was launched in 2005 to tackle urban-rural health inequalities, especially in maternal and child health. We examined national and state level trends in Infant Mortality Rates (IMR) from 2000 through 2009 to: 1) assess whether the NRHM had increased the average annual reduction rate (AARR) of IMR 2) evaluate state-wise progress towards Millennium Development Goals (MDG4) and estimate required AARRs for 'off track' states.

METHODS

Log-linear regression models were applied to national and state IMR data collated from the Sample Registration System (SRS)-India to estimate average annual reduction rates and compare AAARs before and after introduction of NRHM. The log-linear trend of infant mortality rates was also projected forward to 2015.

RESULTS

The infant mortality rate in rural India declined from 74 to 55/1000 live births between 2000 and 2009, with AARR of 3.0% (95% CI=2.6%-3.4%) and the urban-rural gap in infant mortality narrowed (p =0.036). However there was no evidence (p=0.49) that AARR in rural India increased post NRHM (3.4%, 95% CI 2.0-4.7%) compared to pre NRHM (2.8%, 95% CI 2.1%-3.5%). States varied widely in rates of infant mortality reduction. Projections of infant mortality rates suggested that only eight states might be on track to help India achieve MDG4 by 2015.

CONCLUSIONS AND PUBLIC HEALTH IMPLICATIONS

Despite a narrowing urban-rural gap and high AARRs in some states, there was no evidence that the rate of reduction in infant mortality has increased in rural India post NRHM introduction. India appears unlikely to achieve child survival-related NRHM and millennium development goals. Government should revisit the child survival related NRHM strategies and ensure equitable access to health services. More robust monitoring and evaluation mechanisms must be inbuilt for following years.

National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications

BACKGROUND

Preterm birth is the second largest direct cause of child deaths in children younger than 5 years. Yet, data regarding preterm birth (<37 completed weeks of gestation) are not routinely collected by UN agencies, and no systematic country estimates nor time trend analyses have been done. We report worldwide, regional, and national estimates of preterm birth rates for 184 countries in 2010 with time trends for selected countries, and provide a quantitative assessment of the uncertainty surrounding these estimates.

METHODS

We assessed various data sources according to prespecified inclusion criteria. National Registries (563 datapoints, 51 countries), Reproductive Health Surveys (13 datapoints, eight countries), and studies identified through systematic searches and unpublished data (162 datapoints, 40 countries) were included. 55 countries submitted additional data during WHO's country consultation process. For 13 countries with adequate quality and quantity of data, we estimated preterm birth rates using country-level loess regression for 2010. For 171 countries, two regional multilevel statistical models were developed to estimate preterm birth rates for 2010. We estimated time trends from 1990 to 2010 for 65 countries with reliable time trend data and more than 10,000 livebirths per year. We calculated uncertainty ranges for all countries.

FINDINGS

In 2010, an estimated 14·9 million babies (uncertainty range 12·3-18·1 million) were born preterm, 11·1% of all livebirths worldwide, ranging from about 5% in several European countries to 18% in some African countries. More than 60% of preterm babies were born in south Asia and sub-Saharan Africa, where 52% of the global livebirths occur. Preterm birth also affects rich countries, for example, USA has high rates and is one of the ten countries with the highest numbers of preterm births. Of the 65 countries with estimated time trends, only three (Croatia, Ecuador, and Estonia), had reduced preterm birth rates 1990-2010.

INTERPRETATION

The burden of preterm birth is substantial and is increasing in those regions with reliable data. Improved recording of all pregnancy outcomes and standard application of preterm definitions is important. We recommend the addition of a data-quality indicator of the per cent of all live preterm births that are under 28 weeks' gestation. Distinguishing preterm births that are spontaneous from those that are provider-initiated is important to monitor trends associated with increased caesarean sections. Rapid scale up of basic interventions could accelerate progress towards Millennium Development Goal 4 for child survival and beyond.

FUNDING

Bill & Melinda Gates Foundation through grants to Child Health Epidemiology Reference Group (CHERG) and Save the Children's Saving Newborn Lives programme; March of Dimes; the Partnership for Maternal Newborn and Childe Health; and WHO, Department of Reproductive Health and Research.