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Immune-stimulator antibody conjugates (ISAC) combining tumor-targeting monoclonal antibodies with immunostimulatory agents allow targeted delivery of immune activators into tumors. NJH395 is a novel, first-in-class ISAC comprising a Toll‐like receptor 7 (TLR7) agonist conjugated to an anti-HER2 antibody via a noncleavable linker payload. Preclinical characterization showed ISAC-mediated activation of myeloid cells in the presence of antigen-expressing cancer cells, with antigen targeting and TLR7 agonism contributing to antitumor activity. Safety, efficacy, immunogenicity, pharmacokinetics, and pharmacodynamics were investigated in a phase I, multicenter, open-label study in patients with HER2+ non-breast advanced malignancies (NCT03696771). Data from 18 patients enrolled in single ascending dose escalation demonstrated delivery of the TLR7-agonist payload in HER2+ tumor cells and induction of type I IFN responses, which correlated with immune modulation in the tumor microenvironment. Cytokine release syndrome was a common, but manageable, drug-related adverse event. Antidrug antibodies and neuroinflammation at high doses represented significant clinical challenges. Data provide proof-of-mechanism and critical insights for novel immunotherapies.

Supplementary Figure from Preclinical Characterization and Phase I Study of an Anti–HER2-TLR7 Immune-Stimulator Antibody Conjugate in Patients with HER2+ Malignancies

Supplementary Data from Preclinical Characterization and Phase I Study of an Anti–HER2-TLR7 Immune-Stimulator Antibody Conjugate in Patients with HER2+ Malignancies

Supplemental figures 1, 2, and 3 and supplemental tables 1 and 2, showing the antitumor activity of EphA2-ILS-DTXp and the pharmacokinetics in multiple murine tumor models.

Combinations of chemotherapy with immunotherapy have seen recent clinical success, including two approvals of anti–PD-1/L1 agents in combination with taxane-based chemotherapy in non–small cell lung cancer and triple-negative breast cancer. Here, we present a study on the combination activity and mechanistic rationale of a novel EphA2-targeted liposomal taxane (EphA2-ILs-DTXp) and anti–PD-1. This combination was highly active in mouse syngeneic tumor models, with complete responses observed in 3 of 5 models. In the EMT-6 tumor model, combination of EphA2-ILs-DTXp with anti–PD-1 resulted in a 60% complete response rate, with durable responses that were resistant to rechallenge. These responses were not observed in the absence of CD8+ T cells. Characterization of the immune infiltrates in EMT-6 tumors reveals increased CD8+ T cells, increased CD8+ IFNγ+ CTLs, and an increased CD8/regulatory T-cell (Treg) ratio. These immunomodulatory effects were not observed in mice treated with a combination of docetaxel and anti–PD-1. Pharmacokinetic analysis revealed that the AUC of docetaxel was increased 15 times, from 52.1 to 785 ng/mL/hour, when delivered by EphA2-ILs-DTXp. A dose reduction study of EphA2-ILs-DTXp showed a dose–response relationship for both tumor growth inhibition and the CD8/Treg ratio. Our data indicate that synergism between docetaxel and anti–PD-1 is achievable with nanoliposomal delivery.

Supplemental Figure S2: Istiratumab inhibits growth factor-induced AKT phosphorylation across a pancreatic cancer cell line panel.

Table S3

Purpose: Insulin-like growth factor receptor 1 (IGF-1R) is critically involved in pancreatic cancer pathophysiology, promoting cancer cell survival and therapeutic resistance. Assessment of IGF-1R inhibitors in combination with standard-of-care chemotherapy, however, failed to demonstrate significant clinical benefit. The aim of this work is to unravel mechanisms of resistance to IGF-1R inhibition in pancreatic cancer and develop novel strategies to improve the activity of standard-of-care therapies.Experimental Design: Growth factor screening in pancreatic cancer cell lines was performed to identify activators of prosurvival PI3K/AKT signaling. The prevalence of activating growth factors and their receptors was assessed in pancreatic cancer patient samples. Effects of a bispecific IGF-1R and ErbB3 targeting antibody on receptor expression, signaling, cancer cell viability and apoptosis, spheroid growth, and in vivo chemotherapy activity in pancreatic cancer xenograft models were determined.Results: Growth factor screening in pancreatic cancer cells revealed insulin-like growth factor 1 (IGF-1) and heregulin (HRG) as the most potent AKT activators. Both growth factors reduced pancreatic cancer cell sensitivity to gemcitabine or paclitaxel in spheroid growth assays. Istiratumab (MM-141), a novel bispecific antibody that blocks IGF-1R and ErbB3, restored the activity of paclitaxel and gemcitabine in the presence of IGF-1 and HRG in vitro. Dual IGF-1R/ErbB3 blocking enhanced chemosensitivity through inhibition of AKT phosphorylation and promotion of IGF-1R and ErbB3 degradation. Addition of istiratumab to gemcitabine and nab-paclitaxel improved chemotherapy activity in vivo.Conclusions: Our findings suggest a critical role for the HRG/ErbB3 axis and support the clinical exploration of dual IGF-1R/ErbB3 blocking in pancreatic cancer. Clin Cancer Res; 24(12); 2873–85. ©2018 AACR.

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Background Preclinical data suggest that dual blockade of the insulin-like growth factor-1 receptor (IGF-1R) and HER3 pathways has superior activity to IGF-1R blockade alone in pancreatic ductal adenocarcinoma (PDAC). We tested whether istiratumab, an IGF-1R- and ErbB3-bispecific antibody, can enhance the efficacy of standard of care (SOC) chemotherapy in patients with metastatic PDAC selected for high IGF-1 serum levels. Patients and methods CARRIE was an international, randomized, double-blind, placebo-controlled phase II study for patients with previously untreated metastatic PDAC. In part 1, 10 patients were evaluated for pharmacokinetics and safety. In part 2, patients with high free serum IGF-1 levels were randomized 1 : 1 to receive either istiratumab [2.8 g intravenously (i.v.) every 2 weeks] or placebo combined with gemcitabine/nab-paclitaxel at approved dose schedule. The co-primary endpoints were progression-free survival (PFS) in patients with high IGF-1 levels and PFS in patients with both high serum IGF-1 levels and heregulin (HRG)+ tumors. Key secondary endpoints were overall survival (OS), objective response rate (ORR) by RECIST v.1.1, and adverse events (AEs) rate. Results A total of 317 patients were screened, with 88 patients randomized in part 2 (experimental arm n = 43; control n = 45). In the high IGF-1 cohort, median PFS was 3.6 and 7.3 months in the experimental versus control arms, respectively [hazard ratio (HR) = 1.88, P = 0.027]. In the high IGF-1/HRG+ subgroup (n = 44), median PFS was 4.1 and 7.3 months, respectively (HR = 1.39, P = 0.42). Median OS and ORR for the overall population were similar between two arms. No significant difference in serious or grade ≥3 AEs was observed, although low-grade AEs leading to early discontinuation were higher in the experimental (39.5%) versus control arm (24.4%). Conclusions Istiratumab failed to improve the efficacy of SOC chemotherapy in this patient setting. High serum IGF-1 levels did not appear to be an adverse prognostic factor when compared with non-biomarker-selected historic controls. Clinical Trial Registration numbers ClinicalTrials.gov: NCT02399137; EUDRA CT: 2014-004572-34.

Combinations of chemotherapy with immunotherapy have seen recent clinical success, including two approvals of anti–PD-1/L1 agents in combination with taxane-based chemotherapy in non–small cell lung cancer and triple-negative breast cancer. Here, we present a study on the combination activity and mechanistic rationale of a novel EphA2-targeted liposomal taxane (EphA2-ILs-DTXp) and anti–PD-1. This combination was highly active in mouse syngeneic tumor models, with complete responses observed in 3 of 5 models. In the EMT-6 tumor model, combination of EphA2-ILs-DTXp with anti–PD-1 resulted in a 60% complete response rate, with durable responses that were resistant to rechallenge. These responses were not observed in the absence of CD8+ T cells. Characterization of the immune infiltrates in EMT-6 tumors reveals increased CD8+ T cells, increased CD8+ IFNγ+ CTLs, and an increased CD8/regulatory T-cell (Treg) ratio. These immunomodulatory effects were not observed in mice treated with a combination of docetaxel and anti–PD-1. Pharmacokinetic analysis revealed that the AUC of docetaxel was increased 15 times, from 52.1 to 785 ng/mL/hour, when delivered by EphA2-ILs-DTXp. A dose reduction study of EphA2-ILs-DTXp showed a dose–response relationship for both tumor growth inhibition and the CD8/Treg ratio. Our data indicate that synergism between docetaxel and anti–PD-1 is achievable with nanoliposomal delivery.

Antibody-mediated tumour targeting and nanoparticle-mediated encapsulation can reduce the toxicity of antitumour drugs and improve their efficacy. Here, we describe the performance of a nanotherapeutic encapsulating a hydrolytically sensitive docetaxel prodrug and conjugated to an antibody specific for EphA2-a receptor overexpressed in many tumours. Administration of the nanotherapeutic in mice led to slow and sustained release of the prodrug, reduced exposure of active docetaxel in the circulation (compared with administration of the free drug) and maintenance of optimal exposure of the drug in tumour tissue. We also show that administration of the nanotherapeutic in rats and dogs resulted in minimal haematological toxicity, as well as the absence of neutropenia and improved overall tolerability in multiple rodent models. Targeting of the nanotherapeutic to EphA2 improved tumour penetration and resulted in markedly enhanced antitumour activity (compared with administration of free docetaxel and non-targeted nanotherapeutic controls) in multiple tumour-xenografted mice. This nanomedicine could become a potent and safe therapeutic alternative for cancer patients undergoing chemotherapy.

Immune-stimulator antibody conjugates (ISAC) combining tumor-targeting monoclonal antibodies with immunostimulatory agents allow targeted delivery of immune activators into tumors. NJH395 is a novel, first-in-class ISAC comprising a Toll-like receptor 7 (TLR7) agonist conjugated to an anti-HER2 antibody via a noncleavable linker payload. Preclinical characterization showed ISAC-mediated activation of myeloid cells in the presence of antigen-expressing cancer cells, with antigen targeting and TLR7 agonism contributing to antitumor activity. Safety, efficacy, immunogenicity, pharmacokinetics, and pharmacodynamics were investigated in a phase I, multicenter, open-label study in patients with HER2+ non-breast advanced malignancies (NCT03696771). Data from 18 patients enrolled in single ascending dose escalation demonstrated delivery of the TLR7-agonist payload in HER2+ tumor cells and induction of type I IFN responses, which correlated with immune modulation in the tumor microenvironment. Cytokine release syndrome was a common, but manageable, drug-related adverse event. Antidrug antibodies and neuroinflammation at high doses represented significant clinical challenges. Data provide proof-of-mechanism and critical insights for novel immunotherapies.

Background Expression of LAG-3, an inhibitory immunoreceptor, has been linked to reduced T-cell proliferation and cytokine production. LAG525 is a humanized IgG4 anti-LAG-3 antibody which inhibits LAG-3 binding to MHC class II. Spartalizumab is a humanized IgG4 anti-PD-1 mAb which inhibits PD-1 binding with its ligands PD-L1 and PD-L2. Preclinical data have shown promising antitumor activity when blocking LAG-3 and PD-1. Methods The Phase II part of the first-in-human study (NCT02460224) explored LAG525 + spartalizumab in patients with advanced/metastatic non-small cell lung cancer (NSCLC), cutaneous and non-cutaneous melanoma, renal cell carcinoma (RCC), mesothelioma, or triple-negative breast cancer (TNBC). The dose/schedule of LAG525 and spartalizumab was 400 mg IV Q3W and 300 mg IV Q3W, respectively. Half of patients with TNBC naive to anti-PD-1/PD-L1 received LAG525 at 600 mg IV Q4W and spartalizumab at 400 mg IV Q4W. The primary endpoint was overall response rate (ORR) using RECIST v1.1. Results As of June 1, 2020, 235 patients were enrolled in the Phase II part of the study, including patients with NSCLC (n=42), melanoma (n=42), RCC (n=38), mesothelioma (n=57), or TNBC (n=56). In total, 142 patients were naive to, and 93 patients were pretreated with, PD-1/PD-L1 inhibitors. Overall, 232 patients (99%) discontinued treatment, 76% due to progressive disease.ORR and disease control rate by indication and prior anti-PD-1/PD-L1 treatment are summarized below (table 1). Best overall response was 3 (1.3%) CR, 23 (9.8%) PR, 84 (35.7%) SD, 95 (40.4%) PD, and 30 (12.8%) unknown. For patients naive to anti-PD-1/PD-L1, median progression free survival (mPFS) in months (90% CI) was 3.9 (1.7–5.6) for NSCLC, 2.2 (1.6–5.6) for melanoma, 4.4 (2.1–11.1) for RCC, 5.5 (3.5–6.4) for mesothelioma, and 1.9 (1.6–2.6) for TNBC. For patients pretreated with anti-PD-1/PD-L1, mPFS in months (90% CI) was 3.5 (1.9–4.9) for NSCLC, 1.9 (1.8–3.7) for melanoma, 3.0 (1.6–3.9) for RCC, 3.4 (1.8–3.8) for mesothelioma, and 1.7 (1.3–3.4) for TNBC. Adverse events of any grade, regardless of cause, were reported in 233 (99%) patients; the most common (occurring in >20%) were nausea (25%), fatigue (23%), and dyspnea (21%). Conclusions LAG525 + spartalizumab exhibited antitumor activity across different indications, including patients with melanoma, RCC, and mesothelioma who had been pretreated with PD-1/-L1 inhibitors, suggesting that this combination may salvage prior PD-1/-L1 resistance. The combination was well tolerated, and no new safety signals were observed. Biomarker analysis is ongoing. Trial Registration NCT02460224 Ethics Approval This study was approved by an independent ethics committee or institutional review board at each site.

Background NJH395 is a first-in-class immune stimulator antibody conjugate (ISAC) consisting of a toll-like receptor 7 (TLR7) agonist conjugated to an anti-HER2 antibody. Antibody-mediated delivery of TLR7 may limit systemic toxicities previously seen with TLR agonists, while enhancing long-lasting antitumor immune response. In preclinical studies, NJH395 showed promising activity in HER2 expressing xenograft mouse models, and demonstrated immunogenicity and cytokine release in mice and nonhuman primates. Methods This phase 1, first-in-human, open-label, multicenter study (NCT03696771) is evaluating the safety, tolerability, pharmacokinetics, and preliminary efficacy of NJH395 in patients with nonbreast HER2+ advanced malignancies. The study design includes two parts: single-ascending dose (SAD), followed by multiple-ascending dose. Primary endpoint is safety; key secondary endpoints include assessment of pharmacokinetics, immunogenicity, and overall response rate. Tumor response was evaluated 3 weeks after treatment in SAD. Evaluation of pharmacodynamic markers including tumor-infiltrating lymphocytes is the key exploratory objective. Results Here, we report the results of the SAD part of this phase 1 study. As of July 01, 2020, 18 patients (10 males, 8 females; median age, 52.5 years [range, 42–74 years]) were enrolled in 5 dose cohorts (0.1–1.6 mg/kg). The tumor types included HER2+ colorectal cancer (N=11), gastroesophageal adenocarcinoma (N=2), non–small cell lung cancer (N=1), nasopharynx adenocarcinoma (N=1), pancreatic adenocarcinoma (N=1), bladder cancer (N=1), and small intestine adenocarcinoma (N=1). Seventeen patients reported 124 treatment-related adverse events. The most common (occurring in ≥ 20%) adverse events (AEs) of any grade (G), regardless of study drug relationship were cytokine release syndrome (55.6%, G ≤ 2), pyrexia (44.4%), nausea (44.4%), vomiting (33.3%), headache (33.3%), increased aspartate aminotransferase (AST, 33.3%), increased alanine aminotransferase (ALT, 27.8%), and lymphopenia/lymphocyte count decrease (27.8%). The most common ≥ G3 AEs (occurring in ≥ 10%) were lymphopenia/lymphocyte count decrease (27.8%) and increased AST (11.1%). Five dose-limiting toxicities, all G3, were reported in 3 patients: 2 cases of AST increase (1 at 0.2 mg/kg; 1 at 1.6 mg/kg), 1 ALT increase (1.6 mg/kg), 1 aseptic meningitis (1.6 mg/kg), and 1 meningism (1.6 mg/kg). No complete/partial response was seen; 9 patients had stable disease by RECIST v1.1 at 3 weeks post treatment. An increase in CD8-positive T-cells was detected in on-treatment tumor biopsies in 5 patients. Pharmacokinetics showed a greater than dose proportional exposure of NJH395; anti-drug antibodies were detected in all tested patients (14/14). Conclusions Single dosing of NJH395 showed significant but manageable toxicities in patients with nonbreast HER2+ advanced malignancies. Biomarker analysis is ongoing. Acknowledgements The authors thank all patients who participated in the study. The authors acknowledge Kavita Garg, PhD of Novartis Healthcare Pvt Ltd for providing medical editorial assistance with this abstract. Trial Registration ClinicalTrials. gov Identifier: NCT03696771 Ethics Approval The study was performed in accordance with ethical principles of the declaration of Helsinki and good clinical practice guidelines. The protocol and its amendments were approved by institutional review boards of each participating site. Consent Written informed consent was obtained from each patient prior to enrolment in the study.

Ephrin receptor A2 (EphA2) is a member of the Ephrin/Eph receptor cell-to-cell signaling family of molecules, and it plays a key role in cell proliferation, differentiation, and migration. EphA2 is overexpressed in a broad range of cancers, and its expression is in many cases associated with poor prognosis. We recently developed a novel EphA2-targeting antibody-directed nanotherapeutic encapsulating a labile prodrug of docetaxel (EphA2-ILs-DTXp) for the treatment of EphA2-expressing malignancies. Here, we characterized the expression of EphA2 in bladder cancer using immunohistochemistry in 177 human bladder cancer samples and determined the preclinical efficacy of EphA2-ILs-DTXp in four EphA2-positive patient-derived xenograft (PDX) models of the disease, either as a monotherapy, or in combination with gemcitabine. EphA2 expression was detected in 80&ndash, 100% of bladder cancer samples and correlated with shorter patient survival. EphA2 was found to be expressed in tumor cells and/or tumor-associated blood vessels in both primary and metastatic lesions with a concordance rate of approximately 90%. The EphA2-targeted antibody-directed nanotherapeutic EphA2-ILs-DTXp controlled tumor growth, mediated greater regression, and was more active than free docetaxel at equitoxic dosing in all four EphA2-positive bladder cancer PDX models. Combination of EphA2-ILs-DTXp and gemcitabine in one PDX model led to improved tumor growth control compared to monotherapies or the combination of free docetaxel and gemcitabine. These data demonstrating the prevalence of EphA2 in bladder cancers and efficacy of EphA2-ILs-DTXp in PDX models support the clinical exploration of EphA2 targeting in bladder cancer.

Purpose: Insulin-like growth factor receptor 1 (IGF-1R) is critically involved in pancreatic cancer pathophysiology, promoting cancer cell survival and therapeutic resistance. Assessment of IGF-1R inhibitors in combination with standard-of-care chemotherapy, however, failed to demonstrate significant clinical benefit. The aim of this work is to unravel mechanisms of resistance to IGF-1R inhibition in pancreatic cancer and develop novel strategies to improve the activity of standard-of-care therapies. Experimental Design: Growth factor screening in pancreatic cancer cell lines was performed to identify activators of prosurvival PI3K/AKT signaling. The prevalence of activating growth factors and their receptors was assessed in pancreatic cancer patient samples. Effects of a bispecific IGF-1R and ErbB3 targeting antibody on receptor expression, signaling, cancer cell viability and apoptosis, spheroid growth, and in vivo chemotherapy activity in pancreatic cancer xenograft models were determined. Results: Growth factor screening in pancreatic cancer cells revealed insulin-like growth factor 1 (IGF-1) and heregulin (HRG) as the most potent AKT activators. Both growth factors reduced pancreatic cancer cell sensitivity to gemcitabine or paclitaxel in spheroid growth assays. Istiratumab (MM-141), a novel bispecific antibody that blocks IGF-1R and ErbB3, restored the activity of paclitaxel and gemcitabine in the presence of IGF-1 and HRG in vitro. Dual IGF-1R/ErbB3 blocking enhanced chemosensitivity through inhibition of AKT phosphorylation and promotion of IGF-1R and ErbB3 degradation. Addition of istiratumab to gemcitabine and nab-paclitaxel improved chemotherapy activity in vivo. Conclusions: Our findings suggest a critical role for the HRG/ErbB3 axis and support the clinical exploration of dual IGF-1R/ErbB3 blocking in pancreatic cancer. Clin Cancer Res; 24(12); 2873–85. ©2018 AACR.

The cerebellum is a prominent part of the vertebrate hindbrain that is critically involved in the regulation of important body functions such as movement coordination, maintenance of balance and posture, and motor control. Here, we describe a cerebellar window that provides access to the mouse cerebellum for intravital imaging, thereby allowing for a detailed characterization of the dynamic processes in this region of the brain. First, the skull overlying the cerebellum is removed, and then the window is applied to the region of interest. Windows may be exchanged depending on the desired imaging modality. This technique has a variety of applications. In the setting of medulloblastoma, spontaneous or orthotopically implanted lesions can be imaged, and tumor morphology and size can be monitored using ultrasonography. Multiphoton laser-scanning microscopy (MPLSM) or optical-frequency-domain imaging (OFDI) can be applied for in vivo visualization and analysis of cellular and vascular structures in a variety of disease states, including malignancies and ataxia telangiectasia. This protocol describes a novel and rapid method for cerebellar window construction that can be set up in under an hour.

Therapeutically targeting receptor tyrosine kinases has proven to be paramount to overcoming chemotherapy resistance in several cancer indications, improving patient outcomes. Insulin-Like Growth Factor Receptor 1 (IGF-1R) and Epidermal Growth Factor Receptor 3 (ErbB3) have been implicated as two such drivers of resistance, however their simultaneous role in ovarian cancer chemotherapy resistance remains poorly elucidated. The aim of this work is to determine the effects of dual IGF-1R/ErbB3 inhibition on ovarian cancer cell signaling, growth, and in vivo efficacy. Assessment of in vitro chemotherapy response across a panel of ovarian cancer cell lines revealed that increased IGF-1R cell surface expression correlates with decreased sensitivity to chemotherapy, and that growth induced by IGF-1R and ErbB3 ligands is blocked by the tetravalent bispecific antibody targeting IGF-1R and ErbB3, istiratumab. In vitro chemotherapy treatment increased ovarian cancer cell line capacity to activate prosurvival PI3K signaling in response to ligand, which could be prevented with istiratumab treatment. Furthermore, in vivo efficacy of standard of care chemotherapies using a xenograft model of ovarian cancer was potentiated with istiratumab. Our results suggest a role for IGF-1R and ErbB3 in driving chemotherapy resistance of ovarian cancer.

The effective treatment of cerebral metastases from HER2-positive breast cancer remains an unmet need. Recent studies indicate that activated astrocytes and brain endothelial cells exert chemoprotective effects on cancer cells through direct physical interaction. Here we report that the endothelin axis mediates protection of HER2-amplified brain metastatic breast cancers to the anti-HER2 antibody–drug conjugate ado-trastuzumab emtansine (T-DM1). Macitentan, a dual inhibitor of endothelin receptors A and B, improves the efficacy of T-DM1 against breast cancers grown in the brain. We show that direct contact of brain stroma with cancer cells is required for protection to T-DM1. Our data suggest that targeting the endothelin axis may be beneficial when anti-signaling agent and cytotoxic agent are combined. These findings may contribute to the development of therapeutic approaches with enhanced efficacy in the brain microenvironment.

Blood-brain/blood-tumor barriers (BBB and BTB) and interstitial transport may constitute major obstacles to the transport of therapeutics in brain tumors. In this study, we examined the impact of focused ultrasound (FUS) in combination with microbubbles on the transport of two relevant chemotherapy-based anticancer agents in HER2-positive breast cancer brain metastases at cellular resolution: doxorubicin, a non-targeted low molecular weight chemotherapeutic, and ado-trastuzumab emtansine (T-DM1), an antibody-drug conjugate. Using an orthotopic xenograft model of HER2-positive breast cancer brain metastasis and quantitative microscopy we demonstrate significant increases in the extravasation of both agents (7-fold and 2-fold for doxorubicin and T-DM1, respectively) and we provide evidence of increased drug penetration (>100µm vs.

Blood-brain/blood-tumor barriers (BBB and BTB) and interstitial transport may constitute major obstacles to the transport of therapeutics in brain tumors. In this study, we examined the impact of focused ultrasound (FUS) in combination with microbubbles on the transport of two relevant chemotherapy-based anticancer agents in breast cancer brain metastases at cellular resolution: doxorubicin, a nontargeted chemotherapeutic, and ado-trastuzumab emtansine (T-DM1), an antibody-drug conjugate. Using an orthotopic xenograft model of HER2-positive breast cancer brain metastasis and quantitative microscopy, we demonstrate significant increases in the extravasation of both agents (sevenfold and twofold for doxorubicin and T-DM1, respectively), and we provide evidence of increased drug penetration (>100 vs.

Fluorescence imaging is a method of real-time molecular tracking in vivo that has enabled many clinical technologies. Imaging in the shortwave IR (SWIR; 1,000-2,000 nm) promises higher contrast, sensitivity, and penetration depths compared with conventional visible and near-IR (NIR) fluorescence imaging. However, adoption of SWIR imaging in clinical settings has been limited, partially due to the absence of US Food and Drug Administration (FDA)-approved fluorophores with peak emission in the SWIR. Here, we show that commercially available NIR dyes, including the FDA-approved contrast agent indocyanine green (ICG), exhibit optical properties suitable for in vivo SWIR fluorescence imaging. Even though their emission spectra peak in the NIR, these dyes outperform commercial SWIR fluorophores and can be imaged in the SWIR, even beyond 1,500 nm. We show real-time fluorescence imaging using ICG at clinically relevant doses, including intravital microscopy, noninvasive imaging in blood and lymph vessels, and imaging of hepatobiliary clearance, and show increased contrast compared with NIR fluorescence imaging. Furthermore, we show tumor-targeted SWIR imaging with IRDye 800CW-labeled trastuzumab, an NIR dye being tested in multiple clinical trials. Our findings suggest that high-contrast SWIR fluorescence imaging can be implemented alongside existing imaging modalities by switching the detection of conventional NIR fluorescence systems from silicon-based NIR cameras to emerging indium gallium arsenide-based SWIR cameras. Using ICG in particular opens the possibility of translating SWIR fluorescence imaging to human clinical applications. Indeed, our findings suggest that emerging SWIR-fluorescent in vivo contrast agents should be benchmarked against the SWIR emission of ICG in blood.

The compression of brain tissue by a tumor mass is believed to be a major cause of the clinical symptoms seen in patients. However, the biological consequences of these physical stresses on the brain tissue are unknown. Using clinical imaging and preclinical studies, we discovered that a subgroup of primary and metastatic brain tumors, classified as nodular based on the growth pattern, exert compressive solid stress on the surrounding brain tissue, leading to a decrease in local vascular perfusion, as well as neuronal death and impaired function. We demonstrated a causal link between solid stress and neurological dysfunction, by applying and removing cerebral compression, mimicking the mechanics of tumor growth and surgical resection respectively. Finally, we showed that treatment with lithium reduced solid stress-induced neuronal death and improved motor coordination in mice. Our results indicate that brain tumor-generated solid stress impairs neurological function in patients and show lithium as a potential therapeutic intervention to counter these effects.

Background: Brain metastases represent a major problem in the treatment of HER2-positive breast cancer (1). The antibody-drug conjugate ado-trastuzumab emtansine (T-DM1) has shown efficacy in trastuzumab-resistant systemic breast cancer. Here, we tested the hypothesis that T-DM1 could overcome trastuzumab resistance in murine models of brain metastases. Methods: We used previously established animal models of HER2-positive breast cancer brain metastases and organotypic brain slice cultures that recapitulate clinical scenarios (2). We treated mice bearing HER2-positive breast cancer brain metastases with trastuzumab or T-DM1 at equivalent or equipotent doses. Using intravital imaging, molecular techniques and histological analysis we determined tumor growth, mouse survival, cancer cell apoptosis and proliferation, tumor drug distribution, gene expression, and HER2 downstream signaling. Results: T-DM1 significantly delayed the growth of HER2-positive breast cancer brain metastases compared to trastuzumab. These findings were consistent between HER2-driven and PI3K-driven breast tumors. The activity of T-DM1 resulted in a striking survival benefit compared to trastuzumab (median survival for BT474 tumors: 28d for trastuzumab vs 112d for T-DM1, HR=6.2, P Conclusions: Our findings suggest that T-DM1 can overcome resistance to HER2-targeted therapies in the CNS, and warrants clinical investigation for the effective treatment of HER2-positive breast cancer brain metastases. References: 1. Kodack DP, Askoxylakis V, Ferraro GB, et al. Emerging strategies for treating brain metastases from breast cancer. Cancer Cell 2015, 27(2):163-175. 2. Kodack DP, Chung E, Yamashita H, et al. Combined targeting of HER2 and VEGFR2 for effective treatment of HER2-amplified breast cancer brain metastases. Proc Natl Acad Sci U S A 2012, 109(45):E3119-3127. Citation Format: Askoxylakis V, Ferraro G, Kodack D, Badeaux M, Jain R. Ado-trastuzumab emtansine (T-DM1) is effective against established HER2-positive breast cancer brain metastases in mice. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-17-02.

Brain metastasis is an end stage in breast cancer progression. Traditional treatment options have minimal efficacy, and overall survival is on the order of months. The incidence of brain metastatic disease is increasing with the improved management of systemic disease and prolongation of survival. Unfortunately, the targeted therapies that control systemic disease have diminished efficacy against brain lesions. There are reasons to be optimistic, however, as emerging therapies have shown promise in preclinical and early clinical settings. This review discusses recent advances in breast cancer brain metastasis therapy and potential approaches for successful treatment.

Although targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models of breast cancer that faithfully recapitulate the disparate clinical responses in these micro-environments, we observed that brain metastases evade phosphatidylinositide 3-kinase (PI3K) inhibition despite drug accumulation in the brain lesions. In comparison to extracranial disease, we observed increased HER3 expression and phosphorylation in brain lesions. HER3 blockade overcame the resistance of HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, resulting in marked tumor growth delay and improvement in mouse survival. These data provide a mechanistic basis for therapeutic resistance in the brain microenvironment and identify translatable treatment strategies for HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases.

Fluorescence imaging is a method of real-time molecular tracking in vivo that has enabled many clinical technologies. Imaging in the shortwave infrared region (SWIR, 1-2 μm) promises higher contrast, sensitivity, and penetration depths compared to conventional visible and near-infrared (NIR) fluorescence imaging. However, adoption of SWIR imaging in clinical settings has been limited, due in part to the absence of FDA-approved fluorophores with peak emission in the SWIR. Here, we show that commercially available NIR dyes, including the FDA-approved contrast agent indocyanine green (ICG), exhibit optical properties suitable for in vivo SWIR fluorescence imaging. Despite the fact that their emission reaches a maximum in the NIR, these dyes can be imaged non-invasively in vivo in the SWIR spectral region, even beyond 1500 nm. We demonstrate real-time fluorescence angiography at wavelengths beyond 1300 nm using ICG at clinically relevant doses. Furthermore, we show tumortargeted SWIR imaging with trastuzumab labeled with IRDye 800CW, a NIR dye currently being tested in multiple phase II clinical trials. Our findings suggest that high-contrast SWIR fluorescence imaging can be implemented alongside existing imaging modalities by switching the detection of conventional NIR fluorescence systems from silicon-based NIR cameras to emerging indium gallium arsenide (InGaAs) SWIR cameras. Using ICG in particular opens the possibility of translating SWIR fluorescence imaging to human clinical applications.

Five-year survival rates have not increased appreciably for patients with primary and metastatic brain tumors. Nearly 17,000 patients die from primary brain tumors, whereas approximately 200,000 cases are diagnosed with brain metastasis every year in the US alone. At the same time, with improved control of systemic disease, the incidence of brain metastasis is increasing. Thus, novel approaches for improving the treatment outcome for these uniformly fatal diseases are needed urgently. In the review, we summarize the challenges in the treatment of these diseases using antiangiogenic therapies alone or in combination with radio-, chemo- and immuno-therapies. We also discuss the emerging strategies to improve the treatment outcome using both pharmacological approaches to normalize the tumor microenvironment and physical approaches (e.g., focused ultrasound) to modulate the blood-tumor-barrier, along with limitations of each approach. Finally, we offer some new avenues of future research.

Blood-brain/blood-tumor barriers (BBB and BTB) and interstitial transport may constitute major obstacles to the transport of therapeutics in brain tumors. In this study, we examined the impact of focused ultrasound (FUS) in combination with microbubbles on the transport of two relevant chemotherapy-based anticancer agents in HER2-positive breast cancer brain metastases at cellular resolution: the non-targeted chemotherapeutic doxorubicin and the antibody-drug conjugate ado- trastuzumab emtansine (T-DM1). Using an orthotopic xenograft model of HER2-positive breast cancer brain metastasis and quantitative microscopy we demonstrate multifold increases in the extravasation of both agents (7-fold and 2-fold for doxorubicin and T-DM1, respectively) and we provide evidence of increased drug penetration (>100μm vs. < 20μm and 42±7μm vs. 12±4μm for doxorubicin and T-DM1, respectively) after application of FUS as compared to control (non-FUS). Integration of experimental data with physiologically based pharmacokinetic (PBPK) modeling of drug transport reveals that FUS in combination with microbubbles alleviates vascular barriers and enhances interstitial convective transport via increase in hydraulic conductivity. Combination of experimental data and PBPK modeling suggests that FUS in combination with microbubbles increases the endothelial cell transmembrane transport and uptake. PBPK modelling indicates selective increase in transvascular transport of the non- targeted small chemotherapeutic doxorubicin through small vessel-wall pores size with a narrow range (Diameter: 10-50nm). Our work provides a quantitative framework for the optimization of FUS-drug combinations to maximize intratumoral drug delivery and facilitate the development of novel therapeutic strategies against brain metastases.

Although neoadjuvant radiotherapy may improve local control of rectal cancer, its clinical value requires further evaluation as a result of potential side effects and advances in surgical technique. A meta-analysis was performed to assess effectiveness and safety of neoadjuvant radiotherapy in the management of rectal cancer. The following databases were searched: the Cochrane Library, Biosis, Web of Science, Embase, ASCO Abstracts and WHO International Clinical Trials Registry Platform. Randomized controlled trials on the following comparisons were included: (1) neoadjuvant therapy versus surgery alone and (2) neoadjuvant chemoradiotherapy versus neoadjuvant radiotherapy. We identified 17 and 5 relevant trials that enrolled 8,568 and 2,393 patients, respectively. Neoadjuvant radiotherapy improved local control (hazard ratio 0.59; 95 % confidence interval 0.48–0.72) compared to surgery alone even after total mesorectal excision, whereas its benefit in overall survival just failed to reach statistical significance (0.93; 0.85–1.00). However, it was associated with increased perioperative mortality (1.48; 1.08–2.03), in particular if a dose of 5 Gy per fraction was administered (1.85; 1.23–2.78). Chemoradiotherapy improved local control as opposed to radiotherapy (0.53; 0.39–0.72), with no impact on perioperative outcome and long-term survival. Neoadjuvant radiotherapy improves local control in patients with rectal cancer, particularly when chemoradiotherapy is administered. The question if the use of more effective chemotherapy protocols improves overall survival warrants further investigation.

Solid stress and tissue stiffness affect tumour growth, invasion, metastasis and treatment. Unlike stiffness, which can be precisely mapped in tumours, the measurement of solid stresses is challenging. Here, we show that two-dimensional spatial mappings of solid stress and the resulting elastic energy in excised or in situ tumours with arbitrary shapes and wide size ranges can be obtained via three distinct and quantitative techniques that rely on the measurement of tissue displacement after disruption of the confining structures. Application of these methods in models of primary tumours and metastasis revealed that: (i) solid stress depends on both cancer cells and their microenvironment; (ii) solid stress increases with tumour size; and (iii) mechanical confinement by the surrounding tissue significantly contributes to intratumoural solid stress. Further study of the genesis and consequences of solid stress, facilitated by the engineering principles presented here, may lead to significant discoveries and new therapies.

Inhibition of the vascular endothelial growth factor (VEGF) pathway has failed to improve overall survival of patients with glioblastoma (GBM). We previously showed that angiopoietin-2 (Ang-2) overexpression compromised the benefit from anti-VEGF therapy in a preclinical GBM model. Here we investigated whether dual Ang-2/VEGF inhibition could overcome resistance to anti-VEGF treatment. We treated mice bearing orthotopic syngeneic (Gl261) GBMs or human (MGG8) GBM xenografts with antibodies inhibiting VEGF (B20), or Ang-2/VEGF (CrossMab, A2V). We examined the effects of treatment on the tumor vasculature, immune cell populations, tumor growth, and survival in both the Gl261 and MGG8 tumor models. We found that in the Gl261 model, which displays a highly abnormal tumor vasculature, A2V decreased vessel density, delayed tumor growth, and prolonged survival compared with B20. In the MGG8 model, which displays a low degree of vessel abnormality, A2V induced no significant changes in the tumor vasculature but still prolonged survival. In both the Gl261 and MGG8 models A2V reprogrammed protumor M2 macrophages toward the antitumor M1 phenotype. Our findings indicate that A2V may prolong survival in mice with GBM by reprogramming the tumor immune microenvironment and delaying tumor growth.

Phage display represents an attractive screening strategy for the identification of novel, specific binding ligands that could be used for tumor targeting. Recently, a new peptide (CaIX-P1) with affinity for human carbonic anhydrase IX (CAIX) was identified and evaluated. The aim of the present study is to characterize the properties of CaIX-P1 for targeting human colorectal carcinoma and investigate the correlation of peptide binding with the expression of carbonic anhydrase IX. Human colorectal carcinoma HCT116 and HT29 cells were investigated for CAIX expression using Western Blot analysis. Binding and competition studies of 125I-radiolabeled CaIX-P1 were performed on HCT116 cells in vitro. FACS analysis and fluorescence microscopy studies were carried out after cell incubation with fluorescein-labeled CaIX-P1 and rhodamine-labeled anti-human CAIX-mAb. Our studies revealed an enhanced in vitro expression of carbonic anhydrase IX in HCT116 and HT29 cells with increasing cell density. Binding of 125I-labeled-CaIX-P1 on HCT116 cells increased with increasing cell density and correlated to the CAIX expression. FACS analysis demonstrated a correlation of cell labeling between FITC-CaIX-P1 and rhodamine-labeled anti-CAIX-mAb in both HCT116 and HT29 cells. The results of our study indicate that the phage display identified peptide CaIX-P1 might be an attractive candidate for the development of a ligand targeting CAIX in colorectal cancer.

Peptides, proteins and antibodies are promising candidates as carriers for radionuclides in endoradiotherapy. This novel class of pharmaceuticals offers a great potential for the targeted therapy of cancer. The fact that some receptors are overexpressed in several tumor types and can be targeted by small peptides, proteins or antibodies conjugated to radionuclides has been used in the past for the development of peptide endoradiotherapeutic agents such as (90)Y-DOTATOC or radioimmunotherapy of lymphomas with Zevalin. These procedures have been shown to be powerful options for the treatment of cancer patients. Design of new peptide libraries and scaffolds combined with biopanning techniques like phage and ribosome display may lead to the discovery of new specific ligands for target structures overexpressed in malignant tumors. Display methods are high throughput systems which select for high affinity binders. These methods allow the screening of a vast amount of potential binding motifs which may be exposed to either cells overexpressing the target structures or in a cell-free system to the protein itself. Labelling these binders with radionuclides creates new potential tracers for application in diagnosis and endoradiotherapy. This review highlights the advantages and problems of phage and ribosome display for the identification and evaluation of new tumor specific peptides.

Increased metabolism in a number of cellular pathways is a common feature of malignant tumors. This metabolic hallmark of neoplastic tissue led to the development of radiopharmaceuticals for the assessment of transport and enzymatic activity for tumor diagnosis and staging. The malignant transformation causes the activation of oncogenic proteins and signaling pathways that stimulate glycolysis. The resulting high-glucose metabolism of cancer cells allows PET imaging using FDG. Other molecules frequently applied in preclinical and clinical studies are ¹¹C-methionine, tyrosine analogs and choline-based tracers. Using quantitative procedures they enable therapy monitoring by assessment of changes in transport and metabolization. As apoptosis is an important mechanism of cell death in tumors responding to treatment, non-invasive assessment of apoptosis using tracers for detection of phosphatidyl-serine presentation and/or caspase activation could be used as a surrogate marker for therapeutic efficacy.

Ephrin receptor A2 (EphA2) is a member of the Ephrin-Ephrin receptors cell to cell signaling family of molecules and plays a key role in proliferation, differentiation, and migration. EphA2 is overexpressed in a broad range of cancers, including bladder cancer, and is associated with increased metastasis and poor prognosis. Several potential EphA2-targeted therapies were developed and showed promising preclinical activity which failed to translate clinically due to narrow therapeutic window. we propose to use a novel antibody-directed nanotherapeutic (ADN) approach to target EphA2 for the treatment of bladder cancer. This work characterizes the expression of EphA2 in bladder cancer patients, evaluates its prognostic power, and tests an EphA2-targeted ADN, MM-310, in patient-derived xenograft (PDX) models. EphA2 expression in tumors was investigated using a validated immunohistochemistry assay performed in 147 bladder cancer samples, enabling analysis of prevalence and prognostic power. Whole sections of primary and metastatic tumor resections were used to assess EphA2 expression in tumor-associated vessels and tumor cells. Four EphA2+ PDX models were used to evaluate the activity of MM-310 compared to free docetaxel, alone or in combination with gemcitabine. EphA2 was expressed in tumor cells and tumor-associated blood vessels in primary and metastatic lesions. EphA2 overexpression was seen in 80%-100% of tumors and correlated with shorter survival. In the PDX models, MM-310 controlled tumor growth, mediated greater regression, and was more active than free docetaxel at equitoxic dosing (Table). Additionally, the combination of MM-310 and gemcitabine controlled tumor growth better than each drug alone, and outperformed the combination of free docetaxel and gemcitabine in the single PDX model where it was compared. Thus, in bladder cancer models, a docetaxel-based ADN as a monotherapy and in combination with gemcitabine targeted EphA2 and led to significant tumor regression. Maximum tumor regression (%) & Time to regrowth (days)Model NameControlDocetaxelMM-310p valueBL0293-2% & 3 days-58% & 55 days-100% & 120 days Citation Format: Walid Kamoun, Elden Swindell, Christine Pien, Lia Luus, Jason Cain, Irawati Kandela, Richard Huang, Suresh Tipparaju, Dmitri Kirpotin, Wiam Bshara, Vasileios Askoxylakis, Carl Morrison, Daryl Drummond. Targeting EphA2 in bladder cancer using a novel antibody-directed nanotherapeutic [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 5771.

TPS2604Background: Ephrin receptor A2 (EphA2) is expressed in cancer and stroma cells in a wide range of solid tumors. MM-310 is an EphA2-targeting liposomal form of a docetaxel prodrug. Preclinica...

SummaryAfter the cloning of the gene encoding the sodium-iodide symporter several trials were made to develop a radioiodine treatment for multiple tumour entities based on NIS gene transfer. These studies revealed in vitro as well as in vivo a tremendous enhancement of iodide accumulation, which was followed by a rapid efflux. Therapy effects were observed in vitro by clonogenic assays and in vivo by growth inhibition of the treated tumours. However, the interpretation of these results were largely different. Problems of radioiodine therapy after NIS transfer are low efficiency of gene transfer and the short exposure time for the tumours caused by the rapid efflux. Trials to enhance therapeutic efficiency by co-transfer of the gene encoding thyroperoxidase failed due to the low enzyme activity.