(89)Zr-Onartuzumab PET imaging of c-MET receptor dynamics

PURPOSE: c-MET and its ligand hepatocyte growth factor are often dysregulated in human cancers. Dynamic changes in c-MET expression occur and might predict drug efficacy or emergence of resistance. Noninvasive visualization of c-MET dynamics could therefore potentially guide c-MET-directed therapies. We investigated the feasibility of (89)Zr-labelled one-armed c-MET antibody onartuzumab PET for detecting relevant changes in c-MET levels induced by c-MET-mediated epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib resistance or heat shock protein-90 (HSP90) inhibitor NVP-AUY-922 treatment in human non-small-cell lung cancer (NSCLC) xenografts. METHODS: In vitro membrane c-MET levels were determined by flow cytometry. HCC827ErlRes, an erlotinib-resistant clone with c-MET upregulation, was generated from the exon-19 EGFR-mutant human NSCLC cell line HCC827. Mice bearing HCC827 and HCC827ErlRes tumours in opposite flanks underwent (89)Zr-onartuzumab PET scans. The HCC827-xenografted mice underwent (89)Zr-onartuzumab PET scans before treatment and while receiving biweekly intraperitoneal injections of 100 mg/kg NVP-AUY-922 or vehicle. Ex vivo, tumour c-MET immunohistochemistry was correlated with the imaging results. RESULTS: In vitro, membrane c-MET was upregulated in HCC827ErlRes tumours by 213 ± 44% in relation to the level in HCC827 tumours, while c-MET was downregulated by 69 ± 9% in HCC827 tumours following treatment with NVP-AUY-922. In vivo, (89)Zr-onartuzumab uptake was 26% higher (P < 0.05) in erlotinib-resistant HCC827ErlRes than in HCC827 xenografts, while HCC827 tumour uptake was 33% lower (P < 0.001) following NVP-AUY-922 treatment. CONCLUSION: The results show that (89)Zr-onartuzumab PET effectively discriminates relevant changes in c-MET levels and could potentially be used clinically to monitor c-MET status

Combined STING levels and CD103+ T cell infiltration have significant prognostic implications for patients with cervical cancer

Activation of STimulator of INterferon Genes (STING) is important for induction of anti-tumor immunity. A dysfunctional STING pathway is observed in multiple cancer types and associates with poor prognosis and inferior response to immunotherapy. However, the association between STING and prognosis in virally induced cancers such as HPV-positive cervical cancer remains unknown. Here, we investigated the prognostic value of STING protein levels in cervical cancer using tumor tissue microarrays of two patient groups, primarily treated with surgery (n = 251) or radio(chemo)therapy (n = 255). We also studied CD103, an integrin that marks tumor-reactive cytotoxic T cells that reside in tumor epithelium and that is reported to associate with improved prognosis. Notably, we found that a high level of STING protein was an independent prognostic factor for improved survival in both the surgery and radio(chemo)therapy group. High infiltration of CD103+ T cells was associated with improved survival in the radio(chemo)therapy group. The combination of STING levels and CD103+ T cell infiltration is strongly associated with improved prognosis. We conclude that combining the prognostic values of STING and CD103 may improve the risk stratification of cervical cancer patients, independent from established clinical prognostic parameters

ADCC responses and blocking of EGFR-mediated signaling and cell growth by combining the anti-EGFR antibodies imgatuzumab and cetuximab in NSCLC cells

Imgatuzumab is a novel glycoengineered anti-epidermal growth factor receptor (EGFR) monoclonal antibody optimized to induce both antibody-dependent cellular cytotoxicity (ADCC) and EGFR signal transduction inhibition. We investigated antiEGFR monoclonal antibodies imgatuzumab and cetuximab-induced internalization and membranous turnover of EGFR, and whether this affected imgatuzumab-mediated ADCC responses and growth inhibition of non-small cell lung cancer (NSCLC) cells. In a panel of wild-type EGFR expressing human NSCLC cell lines, membranous and total EGFR levels were downregulated more effectively by imgatuzumab when compared with cetuximab. Imgatuzumab plus cetuximab enhanced EGFR internalization and reduced membranous turnover of EGFR, resulting in an even stronger downregulation of EGFR. Immunofluorescent analysis showed that combined treatment increased clustering of receptor-antibody complexes and directed internalized EGFR to lysosomes. The antibody combination potently inhibited intracellular signaling and epidermal growth factor (EGF)-dependent cell proliferation. More importantly, robust EGFR downregulation after 72 hours with the antibody combination did not impair ADCC responses. In conclusion, imgatuzumab plus cetuximab leads to a strong downregulation of EGFR and superior cell growth inhibition in vitro without affecting antibody-induced ADCC responses. These findings support further clinical exploration of the antibody combination in EGFR wild-type NSCLC

Low-dose triple drug combination targeting the PI3K/AKT/mTOR pathway and the MAPK pathway is an effective approach in ovarian clear cell carcinoma

Advanced stage ovarian clear cell carcinoma (OCCC) is poorly responsive to platinum-based chemotherapy and has an unfavorable prognosis. Previous studies revealed heterogeneous mutations in PI3K/AKT/mTOR and MAPK pathway nodules converging in mTORC1/2 activation. Here, we aimed to identify an effective low-dose combination of PI3K/AKT/mTOR pathway and MAPK pathway inhibitors simultaneously targeting key kinases in OCCC to preclude single-inhibitor initiated pathway rewiring and limit toxicity. Small molecule inhibitors of mTORC1/2, PI3K and MEK1/2 were combined at monotherapy IC20 doses in a panel of genetically diverse OCCC cell lines (n = 7) to determine an optimal low-dose combination. The IC20 dose triple combination reduced kinase activity in PI3K/AKT/mTOR and MAPK pathways, prevented single-inhibitor induced feedback mechanisms and inhibited short and long-term proliferation in all seven cell lines. Finally, this low-dose triple drug combination treatment significantly reduced tumor growth in two genetically characterized OCCC patient-derived xenograft (PDX) models without resulting in weight loss in these mice. The effectiveness and tolerability of this combined therapy in PDX models warrants clinical exploration of this treatment strategy for OCCC and might be applicable to other cancer types with a similar genetic background

Molecular Imaging of PD-L1 Expression and Dynamics with the Adnectin-Based PET Tracer F-18-BMS-986192

F-18-BMS-986192, an adnectin-based human programmed cell death ligand 1 (PD-L1) tracer, was developed to noninvasively determine whole-body PD-L1 expression by PET. We evaluated the usability of F-18-BMS-986192 PET to detect different PD-L1 expression levels and therapy-induced changes in PD-L1 expression in tumors. Methods: In vitro binding assays with F-18-BMS-986192 were performed on human tumor cell lines with different total cellular and membrane PD-L1 protein expression levels. Subsequently, PET imaging was performed on immunodeficient mice xenografted with these cell lines. The mice were treated with interferon gamma (IFN gamma) intraperitoneally for 3 d or with the mitogen-activated protein kinase kinase inhibitor selumetinib by oral gavage for 24 h. Afterward, F-18-BMS-986192 was administered intravenously, followed by a 60-min dynamic PET scan. Tracer uptake was expressed as percentage injected dose per gram of tissue. Tissues were collected to evaluate ex vivo tracer biodistribution and to perform flow cytometric, Western blot, and immunohistochemical tumor analyses. Results: F-18-BMS-986192 uptake reflected PD-L1 membrane levels in tumor cell lines, and tumor tracer uptake in mice was associated with PD-L1 expression measured immunohistochemically. In vitro IFN gamma treatment increased PD-L1 expression in the tumor cell lines and caused up to a 12-fold increase in tracer binding. In vivo, IFN gamma affected neither PD-L1 tumor expression measured immunohistochemically nor F-18-BMS-986192 tumor uptake. In vitro, selumetinib downregulated cellular and membrane levels of PD-L1 in tumor cells by 50% as measured by Western blotting and flow cytometry. In mice, selumetinib lowered cellular, but not membrane, PD-L1 levels of tumors, and consequently, no treatment-induced change in F-18-BMS-986192 tumor uptake was observed. Conclusion: F-18-BMS-986192 PET imaging allows detection of membrane-expressed PD-L1 as soon as 60 min after tracer injection. The tracer can discriminate a range of tumor cell PD-L1 membrane expression levels

Expression of CD39 Identifies Activated Intratumoral CD8+T Cells in Mismatch Repair Deficient Endometrial Cancer

Identification of human cancer-reactive CD8+ T cells is crucial for the stratification of patients for immunotherapy and determination of immune-therapeutic effects. To date, these T cells have been identified mainly based on cell surface expression of programmed cell death protein 1 (PD-1) or co-expression of CD103 and CD39. A small subset of CD103- CD39+ CD8+ T cells is also present in tumors, but little is known about these T cells. Here, we report that CD103- CD39+ CD8+ T cells from mismatch repair-deficient endometrial tumors are activated and characterized predominantly by expression of TNFRSF9. In vitro, transforming growth factor-beta (TGF-beta) drives the disappearance of this subset, likely through the conversion of CD103- CD39+ cells to a CD103+ phenotype. On the transcriptomic level, T cell activation and induction of CD39 was associated with a number of tissue residence and TGF-beta responsive transcription factors. Altogether, our data suggest CD39+ CD103- CD8+ tumor-infiltrating T cells are recently activated and likely rapidly differentiate towards tissue residence upon exposure to TGF-beta in the tumor micro-environment, explaining their relative paucity in human tumors

(89)Zr-mAb3481 PET for HER3 tumor status assessment during lapatinib treatment

Treatment of human epidermal growth factor receptor 2 (HER2)-driven breast cancer with tyrosine kinase inhibitor lapatinib can induce a compensatory HER3 increase, which may attenuate antitumor efficacy. Therefore, we explored in vivo HER3 tumor status assessment after lapatinib treatment with zirconium-89 ((89)Zr)-labeled anti-HER3 antibody mAb3481 positron emission tomography (PET). Lapatinib effects on HER3 cell surface expression and mAb3481 internalization were evaluated in human breast (BT474, SKBR3) and gastric (N87) cancer cell lines using flow cytometry. Next, in vivo effects of daily lapatinib treatment on(89)Zr-mAb3481 BT474 and N87 xenograft tumor uptake were studied. PET-scans (BT474 only) were made after daily lapatinib treatment for 9 days, starting 3 days prior to (89)Zr-mAb3481 administration. Subsequently, ex vivo (89)Zr-mAb3481 organ distribution analysis was performed and HER3 tumor levels were measured with Western blot and immunohistochemistry. In vitro, lapatinib increased membranous HER3 in BT474, SKBR3 and N87 cells, and consequently mAb3481 internalization 1.7-fold (BT474), 1.4-fold (SKBR3) and 1.4-fold (N87). (89)Zr-mAb3481 BT474 tumor uptake was remarkably high at SUVmean 5.6±0.6 (51.8±7.7%ID/g) using a 10 μg (89)Zr-mAb3481 protein dose in vehicle-treated mice. However, compared to vehicle, lapatinib did not affect (89)Zr-mAb3481 ex vivo uptake in BT474 and N87 tumors, while HER3 tumor expression remained unchanged. In conclusion, lapatinib increased in vitro HER3 tumor cell expression, but not when these cells were xenografted. (89)Zr-mAb3481 PET accurately reflected HER3 tumor status. (89)Zr-mAb3481 PET showed high, HER3-specific tumor uptake, and such an approach might sensitively assess HER3 tumor heterogeneity and treatment response in patients

Extracellular domain shedding influences specific tumor uptake and organ distribution of the EGFR PET tracer 89Zr-imgatuzumab

Preclinical positron emission tomography (PET) imaging revealed a mismatch between in vivo epidermal growth factor receptor (EGFR) expression and EGFR antibody tracer tumor uptake. Shed EGFR ectodomain (sEGFR), which is present in cancer patient sera, can potentially bind tracer and therefore influence tracer kinetics. To optimize EGFR-PET, we examined the influence of sEGFR levels on tracer kinetics and tumor uptake of EGFR monoclonal antibody Zr-89-imgatuzumab in varying xenograft models. Human cancer cell lines A431 (EGFR overexpressing, epidermoid), A549 and H441 (both EGFR medium expressing, non-small cell lung cancer) were xenografted in mice. Xenografted mice received 10, 25 or 160 mu g Zr-89-imgatuzumab, co-injected with equal doses In-111-IgG control. MicroPET scans were made 24, 72 and 144 h post injection, followed by biodistribution analysis. sEGFR levels in liver and plasma samples were determined by ELISA. Zr-89-imgatuzumab uptake in A431 tumors was highest (29.8 +/- 5.4 % ID/g) in the 160 mu g dose group. Contrary, highest uptake in A549 and H441 tumors was found at the lowest (10 mu g) Zr-89-imgatuzumab dose. High Zr-89-imgatuzumab liver accumulation was found in A431 xenografted mice, which decreased with antibody dose increments. Zr-89-imgatuzumab liver uptake in A549 and H441 xenografted mice was low at all doses. sEGFR levels in liver and plasma of A431 bearing mice were up to 1000-fold higher than levels found in A549, H441 and non-tumor xenografted mice. Zr-89-imgatuzumab effectively visualizes EGFR-expressing tumors. High sEGFR levels can redirect Zr-89-imgatuzumab to the liver, in which case tumor visualization can be improved by increasing tracer antibody dose

A transcriptionally distinct CXCL13+CD103+CD8+ T-cell population is associated with B-cell recruitment and neoantigen load in human cancer

The chemokine CXCL13 mediates recruitment of B cells to tumors and is essential for the formation of tertiary lymphoid structures (TLSs). TLSs are thought to support antitumor immunity and are associated with improved prognosis. However, it remains unknown whether TLSs are formed in response to the general inflammatory character of the tumor microenvironment, or rather, are induced by (neo)antigen-specific adaptive immunity. We here report on the finding that the transforming growth factor beta (TGFβ)-dependent CD103+CD8+ tumor-infiltrating T-cell (TIL) subpopulation expressed and produced CXCL13. Accordingly, CD8+ T cells from peripheral blood activated in the presence of TGFβ upregulated CD103 and secreted CXCL13. Conversely, inhibition of TGFβ receptor signaling abrogated CXCL13 production. CXCL13+CD103+CD8+ TILs correlated with B-cell recruitment, TLSs, and neoantigen burden in six cohorts of human tumors. Altogether, our findings indicated that TGFβ plays a non-canonical role in coordinating immune responses against human tumors and suggest a potential role for CXCL13+CD103+CD8+ TILs in mediating B-cell recruitment and TLS formation in human tumors