PlGF blockade does not inhibit angiogenesis during primary tumor growth.

It has been recently reported that treatment with an anti-placenta growth factor (PlGF) antibody inhibits metastasis and primary tumor growth. Here we show that, although anti-PlGF treatment inhibited wound healing, extravasation of B16F10 cells, and growth of a tumor engineered to overexpress the PlGF receptor (VEGFR-1), neutralization of PlGF using four novel blocking antibodies had no significant effect on tumor angiogenesis in 15 models. Also, genetic ablation of the tyrosine kinase domain of VEGFR-1 in the host did not result in growth inhibition of the anti-VEGF-A sensitive or resistant tumors tested. Furthermore, combination of anti-PlGF with anti-VEGF-A antibodies did not result in greater antitumor efficacy than anti-VEGF-A monotherapy. In conclusion, our data argue against an important role of PlGF during primary tumor growth in most models and suggest that clinical evaluation of anti-PlGF antibodies may be challenging.

Atezolizumab for First-Line Treatment of Metastatic Nonsquamous NSCLC.

BACKGROUND: The cancer-cell-killing property of atezolizumab may be enhanced by the blockade of vascular endothelial growth factor-mediated immunosuppression with bevacizumab. This open-label, phase 3 study evaluated atezolizumab plus bevacizumab plus chemotherapy in patients with metastatic nonsquamous non-small-cell lung cancer (NSCLC) who had not previously received chemotherapy. METHODS: We randomly assigned patients to receive atezolizumab plus carboplatin plus paclitaxel (ACP), bevacizumab plus carboplatin plus paclitaxel (BCP), or atezolizumab plus BCP (ABCP) every 3 weeks for four or six cycles, followed by maintenance therapy with atezolizumab, bevacizumab, or both. The two primary end points were investigator-assessed progression-free survival both among patients in the intention-to-treat population who had a wild-type genotype (WT population; patients with EGFR or ALK genetic alterations were excluded) and among patients in the WT population who had high expression of an effector T-cell (Teff) gene signature in the tumor (Teff-high WT population) and overall survival in the WT population. The ABCP group was compared with the BCP group before the ACP group was compared with the BCP group. RESULTS: In the WT population, 356 patients were assigned to the ABCP group, and 336 to the BCP group. The median progression-free survival was longer in the ABCP group than in the BCP group (8.3 months vs. 6.8 months; hazard ratio for disease progression or death, 0.62; 95% confidence interval [CI], 0.52 to 0.74; P<0.001); the corresponding values in the Teff-high WT population were 11.3 months and 6.8 months (hazard ratio, 0.51 [95% CI, 0.38 to 0.68]; P<0.001). Progression-free survival was also longer in the ABCP group than in the BCP group in the entire intention-to-treat population (including those with EGFR or ALK genetic alterations) and among patients with low or negative programmed death ligand 1 (PD-L1) expression, those with low Teff gene-signature expression, and those with liver metastases. Median overall survival among the patients in the WT population was longer in the ABCP group than in the BCP group (19.2 months vs. 14.7 months; hazard ratio for death, 0.78; 95% CI, 0.64 to 0.96; P=0.02). The safety profile of ABCP was consistent with previously reported safety risks of the individual medicines. CONCLUSIONS: The addition of atezolizumab to bevacizumab plus chemotherapy significantly improved progression-free survival and overall survival among patients with metastatic nonsquamous NSCLC, regardless of PD-L1 expression and EGFR or ALK genetic alteration status. (Funded by F. Hoffmann-La Roche/Genentech; IMpower150 ClinicalTrials.gov number, NCT02366143 .).

Differential regulation of PD-L1 expression by immune and tumor cells in NSCLC and the response to treatment with atezolizumab (anti-PD-L1).

Programmed death-ligand 1 (PD-L1) expression on tumor cells (TCs) by immunohistochemistry is rapidly gaining importance as a diagnostic for the selection or stratification of patients with non-small cell lung cancer (NSCLC) most likely to respond to single-agent checkpoint inhibitors. However, at least two distinct patterns of PD-L1 expression have been observed with potential biological and clinical relevance in NSCLC: expression on TC or on tumor-infiltrating immune cells (ICs). We investigated the molecular and cellular characteristics associated with PD-L1 expression in these distinct cell compartments in 4,549 cases of NSCLC. PD-L1 expression on IC was more prevalent and likely reflected IFN-γ-induced adaptive regulation accompanied by increased tumor-infiltrating lymphocytes and effector T cells. High PD-L1 expression on TC, however, reflected an epigenetic dysregulation of the PD-L1 gene and was associated with a distinct histology described by poor immune infiltration, sclerotic/desmoplastic stroma, and mesenchymal molecular features. Importantly, durable clinical responses to atezolizumab (anti-PD-L1) were observed in patients with tumors expressing high PD-L1 levels on either TC alone [40% objective response rate (ORR)] or IC alone (22% ORR). Thus, PD-L1 expression on TC or IC can independently attenuate anticancer immunity and emphasizes the functional importance of IC in regulating the antitumor T cell response.

Predictive correlates of response to the anti-PD-L1 antibody MPDL3280A in cancer patients.

The development of human cancer is a multistep process characterized by the accumulation of genetic and epigenetic alterations that drive or reflect tumour progression. These changes distinguish cancer cells from their normal counterparts, allowing tumours to be recognized as foreign by the immune system. However, tumours are rarely rejected spontaneously, reflecting their ability to maintain an immunosuppressive microenvironment. Programmed death-ligand 1 (PD-L1; also called B7-H1 or CD274), which is expressed on many cancer and immune cells, plays an important part in blocking the 'cancer immunity cycle' by binding programmed death-1 (PD-1) and B7.1 (CD80), both of which are negative regulators of T-lymphocyte activation. Binding of PD-L1 to its receptors suppresses T-cell migration, proliferation and secretion of cytotoxic mediators, and restricts tumour cell killing. The PD-L1-PD-1 axis protects the host from overactive T-effector cells not only in cancer but also during microbial infections. Blocking PD-L1 should therefore enhance anticancer immunity, but little is known about predictive factors of efficacy. This study was designed to evaluate the safety, activity and biomarkers of PD-L1 inhibition using the engineered humanized antibody MPDL3280A. Here we show that across multiple cancer types, responses (as evaluated by Response Evaluation Criteria in Solid Tumours, version 1.1) were observed in patients with tumours expressing high levels of PD-L1, especially when PD-L1 was expressed by tumour-infiltrating immune cells. Furthermore, responses were associated with T-helper type 1 (TH1) gene expression, CTLA4 expression and the absence of fractalkine (CX3CL1) in baseline tumour specimens. Together, these data suggest that MPDL3280A is most effective in patients in which pre-existing immunity is suppressed by PD-L1, and is re-invigorated on antibody treatment.

Atezolizumab in combination with carboplatin plus nab-paclitaxel chemotherapy compared with chemotherapy alone as first-line treatment for metastatic non-squamous non-small-cell lung cancer (IMpower130): a multicentre, randomised, open-label, phase 3 trial.

BACKGROUND: Atezolizumab (a monoclonal antibody against PD-L1), which restores anticancer immunity, improved overall survival in patients with previously treated non-small-cell lung cancer and also showed clinical benefit when combined with chemotherapy as first-line treatment of non-small-cell lung cancer. IMpower130 aimed to assess the efficacy and safety of atezolizumab plus chemotherapy versus chemotherapy alone as first-line therapy for non-squamous non-small-cell lung cancer. METHODS: IMpower130 was a multicentre, randomised, open-label, phase 3 study done in 131 centres across eight countries (the USA, Canada, Belgium, France, Germany, Italy, Spain, and Israel). Eligible patients were aged 18 years or older, and had histologically or cytologically confirmed stage IV non-squamous non-small-cell lung cancer, an Eastern Cooperative Oncology Group performance status of 0 or 1, and received no previous chemotherapy for stage IV disease. Patients were randomly assigned (2:1; permuted block [block size of six] with an interactive voice or web response system) to receive atezolizumab (1200 mg intravenously every 3 weeks) plus chemotherapy (carboplatin [area under the curve 6 mg/mL per min every 3 weeks] plus nab-paclitaxel [100 mg/m2 intravenously every week]) or chemotherapy alone for four or six 21-day cycles followed by maintenance therapy. Stratification factors were sex, baseline liver metastases, and PD-L1 tumour expression. Co-primary endpoints were investigator-assessed progression-free survival and overall survival in the intention-to-treat wild-type (ie, EGFRwt and ALKwt) population. The safety population included patients who received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT02367781. FINDINGS: Between April 16, 2015, and Feb 13, 2017, 724 patients were randomly assigned and 723 were included in the intention-to-treat population (one patient died before randomisation, but was assigned to a treatment group; this patient was excluded from the intention-to-treat population) of the atezolizumab plus chemotherapy group (483 patients in the intention-to-treat population and 451 patients in the intention-to-treat wild-type population) or the chemotherapy group (240 patients in the intention-to-treat population and 228 patients in the intention-to-treat wild-type population). Median follow-up in the intention-to-treat wild-type population was similar between groups (18·5 months [IQR 15·2-23·6] in the atezolizumab plus chemotherapy group and 19·2 months [15·4-23·0] in the chemotherapy group). In the intention-to-treat wild-type population, there were significant improvements in median overall survival (18·6 months [95% CI 16·0-21·2] in the atezolizumab plus chemotherapy group and 13·9 months [12·0-18·7] in the chemotherapy group; stratified hazard ratio [HR] 0·79 [95% CI 0·64-0·98]; p=0·033) and median progression-free survival (7·0 months [95% CI 6·2-7·3] in the atezolizumab plus chemotherapy group and 5·5 months [4·4-5·9] in the chemotherapy group; stratified HR 0·64 [95% CI 0·54-0·77]; p<0·0001]). The most common grade 3 or worse treatment-related adverse events were neutropenia (152 [32%] of 473 in the atezolizumab plus chemotherapy group vs 65 [28%] of 232 in the chemotherapy group), anaemia (138 [29%] vs 47 [20%]), and decreased neutrophil count (57 [12%] vs 19 [8%]). Treatment-related serious adverse events were reported in 112 (24%) of 473 patients in the atezolizumab plus chemotherapy group and 30 (13%) of 232 patients in the chemotherapy group. Treatment-related (any treatment) deaths occurred in eight (2%) of 473 patients in the atezolizumab plus chemotherapy group and one (<1%) of 232 patients in the chemotherapy group. INTERPRETATION: IMpower130 showed a significant and clinically meaningful improvement in overall survival and a significant improvement in progression-free survival with atezolizumab plus chemotherapy versus chemotherapy as first-line treatment of patients with stage IV non-squamous non-small-cell lung cancer and no ALK or EGFR mutations. No new safety signals were identified. This study supports the benefit of atezolizumab, in combination with platinum-based chemotherapy, as first-line treatment of metastatic non-small-cell lung cancer. FUNDING: F. Hoffmann-La Roche.

Atezolizumab versus docetaxel in patients with previously treated non-small-cell lung cancer (OAK): a phase 3, open-label, multicentre randomised controlled trial.

BACKGROUND: Atezolizumab is a humanised antiprogrammed death-ligand 1 (PD-L1) monoclonal antibody that inhibits PD-L1 and programmed death-1 (PD-1) and PD-L1 and B7-1 interactions, reinvigorating anticancer immunity. We assessed its efficacy and safety versus docetaxel in previously treated patients with non-small-cell lung cancer. METHODS: We did a randomised, open-label, phase 3 trial (OAK) in 194 academic or community oncology centres in 31 countries. We enrolled patients who had squamous or non-squamous non-small-cell lung cancer, were 18 years or older, had measurable disease per Response Evaluation Criteria in Solid Tumors, and had an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients had received one to two previous cytotoxic chemotherapy regimens (one or more platinum based combination therapies) for stage IIIB or IV non-small-cell lung cancer. Patients with a history of autoimmune disease and those who had received previous treatments with docetaxel, CD137 agonists, anti-CTLA4, or therapies targeting the PD-L1 and PD-1 pathway were excluded. Patients were randomly assigned (1:1) to intravenously receive either atezolizumab 1200 mg or docetaxel 75 mg/m2 every 3 weeks by permuted block randomisation (block size of eight) via an interactive voice or web response system. Coprimary endpoints were overall survival in the intention-to-treat (ITT) and PD-L1-expression population TC1/2/3 or IC1/2/3 (≥1% PD-L1 on tumour cells or tumour-infiltrating immune cells). The primary efficacy analysis was done in the first 850 of 1225 enrolled patients. This study is registered with ClinicalTrials.gov, number NCT02008227. FINDINGS: Between March 11, 2014, and April 29, 2015, 1225 patients were recruited. In the primary population, 425 patients were randomly assigned to receive atezolizumab and 425 patients were assigned to receive docetaxel. Overall survival was significantly longer with atezolizumab in the ITT and PD-L1-expression populations. In the ITT population, overall survival was improved with atezolizumab compared with docetaxel (median overall survival was 13·8 months [95% CI 11·8-15·7] vs 9·6 months [8·6-11·2]; hazard ratio [HR] 0·73 [95% CI 0·62-0·87], p=0·0003). Overall survival in the TC1/2/3 or IC1/2/3 population was improved with atezolizumab (n=241) compared with docetaxel (n=222; median overall survival was 15·7 months [95% CI 12·6-18·0] with atezolizumab vs 10·3 months [8·8-12·0] with docetaxel; HR 0·74 [95% CI 0·58-0·93]; p=0·0102). Patients in the PD-L1 low or undetectable subgroup (TC0 and IC0) also had improved survival with atezolizumab (median overall survival 12·6 months vs 8·9 months; HR 0·75 [95% CI 0·59-0·96]). Overall survival improvement was similar in patients with squamous (HR 0·73 [95% CI 0·54-0·98]; n=112 in the atezolizumab group and n=110 in the docetaxel group) or non-squamous (0·73 [0·60-0·89]; n=313 and n=315) histology. Fewer patients had treatment-related grade 3 or 4 adverse events with atezolizumab (90 [15%] of 609 patients) versus docetaxel (247 [43%] of 578 patients). One treatment-related death from a respiratory tract infection was reported in the docetaxel group. INTERPRETATION: To our knowledge, OAK is the first randomised phase 3 study to report results of a PD-L1-targeted therapy, with atezolizumab treatment resulting in a clinically relevant improvement of overall survival versus docetaxel in previously treated non-small-cell lung cancer, regardless of PD-L1 expression or histology, with a favourable safety profile. FUNDING: F. Hoffmann-La Roche Ltd, Genentech, Inc.

Atezolizumab versus docetaxel for patients with previously treated non-small-cell lung cancer (POPLAR): a multicentre, open-label, phase 2 randomised controlled trial.

BACKGROUND: Outcomes are poor for patients with previously treated, advanced or metastatic non-small-cell lung cancer (NSCLC). The anti-programmed death ligand 1 (PD-L1) antibody atezolizumab is clinically active against cancer, including NSCLC, especially cancers expressing PD-L1 on tumour cells, tumour-infiltrating immune cells, or both. We assessed efficacy and safety of atezolizumab versus docetaxel in previously treated NSCLC, analysed by PD-L1 expression levels on tumour cells and tumour-infiltrating immune cells and in the intention-to-treat population. METHODS: In this open-label, phase 2 randomised controlled trial, patients with NSCLC who progressed on post-platinum chemotherapy were recruited in 61 academic medical centres and community oncology practices across 13 countries in Europe and North America. Key inclusion criteria were Eastern Cooperative Oncology Group performance status 0 or 1, measurable disease by Response Evaluation Criteria In Solid Tumors version 1.1 (RECIST v1.1), and adequate haematological and end-organ function. Patients were stratified by PD-L1 tumour-infiltrating immune cell status, histology, and previous lines of therapy, and randomly assigned (1:1) by permuted block randomisation (with a block size of four) using an interactive voice or web system to receive intravenous atezolizumab 1200 mg or docetaxel 75 mg/m(2) once every 3 weeks. Baseline PD-L1 expression was scored by immunohistochemistry in tumour cells (as percentage of PD-L1-expressing tumour cells TC3≥50%, TC2≥5% and <50%, TC1≥1% and <5%, and TC0<1%) and tumour-infiltrating immune cells (as percentage of tumour area: IC3≥10%, IC2≥5% and <10%, IC1≥1% and <5%, and IC0<1%). The primary endpoint was overall survival in the intention-to-treat population and PD-L1 subgroups at 173 deaths. Biomarkers were assessed in an exploratory analysis. We assessed safety in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT01903993. FINDINGS: Patients were enrolled between Aug 5, 2013, and March 31, 2014. 144 patients were randomly allocated to the atezolizumab group, and 143 to the docetaxel group. 142 patients received at least one dose of atezolizumab and 135 received docetaxel. Overall survival in the intention-to-treat population was 12·6 months (95% CI 9·7-16·4) for atezolizumab versus 9·7 months (8·6-12·0) for docetaxel (hazard ratio [HR] 0·73 [95% CI 0·53-0·99]; p=0·04). Increasing improvement in overall survival was associated with increasing PD-L1 expression (TC3 or IC3 HR 0·49 [0·22-1·07; p=0·068], TC2/3 or IC2/3 HR 0·54 [0·33-0·89; p=0·014], TC1/2/3 or IC1/2/3 HR 0·59 [0·40-0·85; p=0·005], TC0 and IC0 HR 1·04 [0·62-1·75; p=0·871]). In our exploratory analysis, patients with pre-existing immunity, defined by high T-effector-interferon-γ-associated gene expression, had improved overall survival with atezolizumab. 11 (8%) patients in the atezolizumab group discontinued because of adverse events versus 30 (22%) patients in the docetaxel group. 16 (11%) patients in the atezolizumab group versus 52 (39%) patients in the docetaxel group had treatment-related grade 3-4 adverse events, and one (<1%) patient in the atezolizumab group versus three (2%) patients in the docetaxel group died from a treatment-related adverse event. INTERPRETATION: Atezolizumab significantly improved survival compared with docetaxel in patients with previously treated NSCLC. Improvement correlated with PD-L1 immunohistochemistry expression on tumour cells and tumour-infiltrating immune cells, suggesting that PD-L1 expression is predictive for atezolizumab benefit. Atezolizumab was well tolerated, with a safety profile distinct from chemotherapy. FUNDING: F Hoffmann-La Roche/Genentech Inc.

Oncogenic RAS pathway activation promotes resistance to anti-VEGF therapy through G-CSF-induced neutrophil recruitment.

Granulocyte-colony stimulating factor (G-CSF) promotes mobilization of CD11b(+)Gr1(+) myeloid cells and has been implicated in resistance to anti-VEGF therapy in mouse models. High G-CSF production has been associated with a poor prognosis in cancer patients. Here we show that activation of the RAS/MEK/ERK pathway regulates G-CSF expression through the Ets transcription factor. Several growth factors induced G-CSF expression by a MEK-dependent mechanism. Inhibition of G-CSF release with a MEK inhibitor markedly reduced G-CSF production in vitro and synergized with anti-VEGF antibodies to reduce CD11b(+)Ly6G(+) neutrophil mobilization and tumor growth and led to increased survival in animal models of cancer, including a genetically engineered mouse model of pancreatic adenocarcinoma. Analysis of biopsies from pancreatic cancer patients revealed increased phospho-MEK, G-CSF, and Ets expression and enhanced neutrophil recruitment compared with normal pancreata. These results provide insights into G-CSF regulation and on the mechanism of action of MEK inhibitors and point to unique anticancer strategies.

Phenotypical differences in connective tissue cells emerging from microvascular pericytes in response to overexpression of PDGF-B and TGF-ß1 in normal skin in vivo.

Fibrosis is a deleterious consequence of chronic inflammation in a number of human pathologies ultimately leading to organ dysfunction and failure. Two growth factors that are important in blood vessel physiology and tissue fibrosis, platelet-derived growth factor (PDGF)-B and transforming growth factor (TGF)-ß1, were investigated. Adenoviral vectors were used to induce transient overexpression of these growth factors in mouse skin. Changes in tissue structure and protein and mRNA expressions were investigated. Both PDGF-B and TGF-ß1 could initiate but neither could sustain angiogenesis. Instead, vascular regression was observed. Overexpression of both TGF-ß1 and PDGF-B led to a marked macrophage influx and an expansion of the connective tissue cell population. Over time, this effect was sustained in mice treated with TGF-ß1, whereas it was partially reversible in mice treated with PDGF-B. On the basis of structure and expression of phenotypical markers, the emerging connective tissue cell population may originate from microvascular pericytes. TGF-ß1 induced expansion of connective tissue cells with a myofibroblast phenotype, whereas PDGF-B induced a fibroblast phenotype negative for α-smooth muscle actin. TGF-ß1 and PDGF-B overexpressions mediated distinct effects on mRNA transcript levels of fibrillar procollagens, their modifying enzymes, small leucin-rich repeat proteoglycans, and matricellular proteins affecting both the composition and the quantity of the extracellular matrix. This study offers new insight into the effects of PDGF-B and TGF-ß1 on the vasculature and connective tissue in vivo.

Transcriptional induction of salt-inducible kinase 1 by transforming growth factor ß leads to negative regulation of type I receptor signaling in cooperation with the Smurf2 ubiquitin ligase.

Transforming growth factor ß (TGFß) regulates many physiological processes and requires control mechanisms to safeguard proper and timely action. We have previously described how negative regulation of TGFß signaling is controlled by the serine/threonine kinase salt-inducible kinase 1 (SIK1). SIK1 forms complexes with the TGFß type I receptor and with the inhibitory Smad7 and down-regulates the type I receptor. We now demonstrate that TGFß induces SIK1 levels via a direct transcriptional mechanism that implicates the Smad proteins, and we have mapped a putative enhancer element on the SIK1 gene. We provide evidence that the ubiquitin ligase Smurf2 forms complexes and functionally cooperates with SIK1. Both the kinase activity of SIK1 and the ubiquitin ligase activity of Smurf2 are important for proper type I receptor turnover. We also show that knockdown of endogenous SIK1 and Smurf2 enhances physiological signaling by TGFß that leads to epithelial growth arrest. In conclusion, TGFß induces expression of Smad7, Smurf2, and SIK1, the products of which physically and functionally interlink to control the activity of this pathway.

Development of a robust flow cytometry-based pharmacodynamic assay to detect phospho-protein signals for phosphatidylinositol 3-kinase inhibitors in multiple myeloma.

BACKGROUND: The phosphatidylinositol 3-kinase (PI3K) pathway plays an important role in multiple myeloma (MM), a blood cancer associated with uncontrolled proliferation of bone marrow plasma cells. This study aimed to develop a robust clinical pharmacodynamic (PD) assay to measure the on-target PD effects of the selective PI3K inhibitor GDC-0941 in MM patients. METHODS: We conducted an in vitro drug wash-out study to evaluate the feasibility of biochemical approaches in measuring the phosphorylation of S6 ribosomal protein (S6), one of the commonly used PD markers for PI3K pathway inhibition. We then developed a 7-color phospho-specific flow cytometry assay, or phospho flow assay, to measure the phosphorylation state of intracellular S6 in bone marrow aspirate (BMA) and peripheral blood (PB). Integrated mean fluorescence intensity (iMFI) was used to calculate fold changes of phosphorylation. Assay sensitivity was evaluated by comparing phospho flow with Meso Scale Discovery (MSD) and immunohistochemistry (IHC) assays. Finally, a sample handling method was developed to maintain the integrity of phospho signal during sample shipping and storage to ensure clinical application. RESULTS: The phospho flow assay provided single-cell PD monitoring of S6 phosphorylation in tumor and surrogate cells using fixed BMA and PB, assessing pathway modulation in response to GDC-0941 with sensitivity similar to that of MSD assay. The one-shot sample fixation and handling protocol herein demonstrated exceptional preservation of protein phosphorylation. In contrast, the IHC assay was less sensitive in terms of signal quantification while the biochemical approach (MSD) was less suitable to assess PD activities due to the undesirable impact associated with cell isolation on the protein phosphorylation in tumor cells. CONCLUSIONS: We developed a robust PD biomarker assay for the clinical evaluation of PI3K inhibitors in MM, allowing one to decipher the PD response in a relevant cell population. To our knowledge, this is the first report of an easily implemented clinical PD assay that incorporates an unbiased one-shot sample handling protocol, all (staining)-in-one (tube) phospho flow staining protocol, and an integrated modified data analysis for PD monitoring of kinase inhibitors in relevant cell populations in BMA and PB. The methods described here ensure a real-time, reliable and reproducible PD readout, which can provide information for dose selection as well as help to identify optimal combinations of targeted agents in early clinical trials.

Differential drug class-specific metastatic effects following treatment with a panel of angiogenesis inhibitors.

Inhibiting angiogenesis has become an important therapeutic strategy for cancer treatment but, like other current targeted therapies, benefits experienced for late-stage cancers can be curtailed by inherent refractoriness or by acquired drug resistance, requiring a need for better mechanistic understanding of such effects. Numerous preclinical studies have demonstrated that VEGF pathway inhibitors suppress primary tumour growth and metastasis. However, it has been recently reported that short-term VEGF and VEGFR inhibition can paradoxically accelerate tumour invasiveness and metastasis in certain models. Here we comprehensively compare the effects of both antibody and small molecule receptor tyrosine kinase (RTK) inhibitors targeting the VEGF-VEGFR pathway, using short-term therapy in various mouse models of metastasis. Our findings demonstrate that antibody inhibition of VEGF pathway molecules does not promote metastasis, in contrast to selected small molecule RTK inhibitors at elevated-therapeutic drug dosages. In particular, a multi-targeted RTK inhibitor, sunitinib, which most profoundly potentiated metastasis, also increased lung vascular permeability and promoted tumour cell extravasation. Mechanistically, sunitinib, but not anti-VEGF treatment, attenuated endothelial barrier function in culture and caused a global inhibition of protein tyrosine phosphorylation, including molecules important for maintaining endothelial cell-cell junctions. Together these findings indicate that, rather than a specific consequence of inhibiting the VEGF signalling pathway, pharmacological inhibitors of the VEGF pathway can have dose- and drug class-dependent side-effects on the host vasculature. These findings also advocate for the continued identification of mechanisms of resistance to anti-angiogenics and for therapy development to overcome it.

Granulocyte-colony stimulating factor promotes lung metastasis through mobilization of Ly6G+Ly6C+ granulocytes.

Priming of the organ-specific premetastatic sites is thought to be an important yet incompletely understood step during metastasis. In this study, we show that the metastatic tumors we examined overexpress granulocyte-colony stimulating factor (G-CSF), which expands and mobilizes Ly6G+Ly6C+ granulocytes and facilitates their subsequent homing at distant organs even before the arrival of tumor cells. Moreover, G-CSF-mobilized Ly6G+Ly6C+ cells produce the Bv8 protein, which has been implicated in angiogenesis and mobilization of myeloid cells. Anti-G-CSF or anti-Bv8 antibodies significantly reduced lung metastasis. Transplantation of Bv8 null fetal liver cells into lethally irradiated hosts also reduced metastasis. We identified an unexpected role for Bv8: the ability to stimulate tumor cell migration through activation of one of the Bv8 receptors, prokineticin receptor (PKR)-1. Finally, we show that administration of recombinant G-CSF is sufficient to increase the numbers of Ly6G+Ly6C+ cells in organ-specific metastatic sites and results in enhanced metastatic ability of several tumors.

G-CSF-initiated myeloid cell mobilization and angiogenesis mediate tumor refractoriness to anti-VEGF therapy in mouse models.

Recent studies suggest that tumor-associated CD11b(+)Gr1(+) myeloid cells contribute to refractoriness to antiangiogenic therapy with an anti-VEGF-A antibody. However, the mechanisms of peripheral mobilization and tumor-homing of CD11b(+)Gr1(+) cells are unclear. Here, we show that, compared with other cytokines [granulocyte-macrophage colony stimulating factor (GM-CSF), stromal derived factor 1alpha, and placenta growth factor], G-CSF and the G-CSF-induced Bv8 protein have preferential expression in refractory tumors. Treatment of refractory tumors with the combination of anti-VEGF and anti-G-CSF (or anti-Bv8) reduced tumor growth compared with anti-VEGF-A monotherapy. Anti-G-CSF treatment dramatically suppressed circulating or tumor-associated CD11b(+)Gr1(+) cells, reduced Bv8 levels, and affected the tumor vasculature. Conversely, G-CSF delivery to animals bearing anti-VEGF sensitive tumors resulted in reduced responsiveness to anti-VEGF-A treatment through induction of Bv8-dependent angiogenesis. We conclude that, at least in the models examined, G-CSF expression by tumor or stromal cells is a determinant of refractoriness to anti-VEGF-A treatment.

Case report: A persistently expanded T cell response in an exceptional responder to radiation and atezolizumab for metastatic non-small cell lung cancer.

Most patients with advanced non-small cell lung cancer (NSCLC) do not achieve a durable remission after treatment with immune checkpoint inhibitors. Here we report the clinical history of an exceptional responder to radiation and anti-program death-ligand 1 (PD-L1) monoclonal antibody, atezolizumab, for metastatic NSCLC who remains in a complete remission more than 8 years after treatment. Sequencing of the patient's T cell repertoire from a metastatic lesion and the blood before and after anti-PD-L1 treatment revealed oligoclonal T cell expansion. Characterization of the dominant T cell clone, which comprised 10% of all clones and increased 10-fold in the blood post-treatment, revealed an activated CD8+ phenotype and reactivity against 4 HLA-A2 restricted neopeptides but not viral or wild-type human peptides, suggesting tumor reactivity. We hypothesize that the patient's exceptional response to anti-PD-L1 therapy may have been achieved by increased tumor immunogenicity promoted by pre-treatment radiation therapy as well as long-term persistence of oligoclonal expanded circulating T cells.

C-reactive protein reduction post treatment is associated with improved survival in atezolizumab (anti-PD-L1) treated non-small cell lung cancer patients.

PURPOSE: Overall survival (OS) is the most significant endpoint for evaluation of treatment benefit with checkpoint inhibitors (CPI) in cancer. We evaluated serum C-reactive protein (CRP) in non-small cell lung cancer (NSCLC) trials with atezolizumab (anti-PD-L1) as an early OS surrogate. METHODS: Serum from patients enrolled in randomized Phase II (n = 240) and Phase III (n = 701) trials of NSCLC patients (POPLAR, OAK) who progressed on prior-platinum chemotherapy, were analyzed for CRP levels over time. Patients were grouped by changes in CRP levels post-treatment as either increased (≥ 1.5 fold), decreased (≤ 1.5 fold) or unchanged (within +1.5 fold) relative to pre-treatment levels to assess association with progression free survival (PFS) and OS. RESULTS: Decrease in serum CRP levels at 6 weeks relative to pre-treatment were observed in patients with RECIST1.1 based complete or partial responses (CR/PR) to atezolizumab whereas patients with disease progression (PD) demonstrated an increase in CRP levels in the Phase II POPLAR study, and confirmed in the Phase III OAK study. Decrease in serum CRP as early as six weeks post treatment predicted improved PFS and OS, even in patients who were determined as stable disease (SD) in their first scan. This effect was not observed in the chemotherapy arms. CONCLUSION: Modulation of serum CRP correlates with clinical outcome post-atezolizumab treatment. This routine lab test may provide utility in informing OS signals as early as 6 weeks post-initiation of therapy with CPIs in NSCLC.

Immune-stimulating antibody conjugates elicit robust myeloid activation and durable antitumor immunity.

Innate pattern recognition receptor agonists, including Toll-like receptors (TLRs), alter the tumor microenvironment and prime adaptive antitumor immunity. However, TLR agonists present toxicities associated with widespread immune activation after systemic administration. To design a TLR-based therapeutic suitable for systemic delivery and capable of safely eliciting tumor-targeted responses, we developed immune-stimulating antibody conjugates (ISACs) comprising a TLR7/8 dual agonist conjugated to tumor-targeting antibodies. Systemically administered human epidermal growth factor receptor 2 (HER2)-targeted ISACs were well tolerated and triggered a localized immune response in the tumor microenvironment that resulted in tumor clearance and immunological memory. Mechanistically, ISACs required tumor antigen recognition, Fcγ-receptor-dependent phagocytosis and TLR-mediated activation to drive tumor killing by myeloid cells and subsequent T-cell-mediated antitumor immunity. ISAC-mediated immunological memory was not limited to the HER2 ISAC target antigen since ISAC-treated mice were protected from rechallenge with the HER2- parental tumor. These results provide a strong rationale for the clinical development of ISACs.

Intratumoral CD103+ CD8+ T cells predict response to PD-L1 blockade.

BACKGROUND: CD8+ tissue-resident memory T (TRM) cells, marked by CD103 (ITGAE) expression, are thought to actively suppress cancer progression, leading to the hypothesis that their presence in tumors may predict response to immunotherapy. METHODS: Here, we test this by combining high-dimensional single-cell modalities with bulk tumor transcriptomics from 1868 patients enrolled in lung and bladder cancer clinical trials of atezolizumab (anti-programmed cell death ligand 1 (PD-L1)). RESULTS: ITGAE was identified as the most significantly upregulated gene in inflamed tumors. Tumor CD103+ CD8+ TRM cells exhibited a complex phenotype defined by the expression of checkpoint regulators, cytotoxic proteins, and increased clonal expansion. CONCLUSIONS: Our analyses indeed demonstrate that the presence of CD103+ CD8+ TRM cells, quantified by tracking intratumoral CD103 expression, can predict treatment outcome, suggesting that patients who respond to PD-1/PD-L1 blockade are those who exhibit an ongoing antitumor T-cell response.

Clinical Activity and Safety of Atezolizumab in a Phase 1 Study of Patients With Relapsed/Refractory Small-Cell Lung Cancer.

BACKGROUND: Programmed death-ligand 1 (PD-L1) protein is expressed in various cancers, including small-cell lung cancer (SCLC). Atezolizumab inhibits PD-L1 signaling, thus restoring tumor-specific T-cell immunity. Here, we report results from the first-in-human phase 1 PCD4989g study (NCT01375842) of atezolizumab, in a cohort of patients with relapsed/refractory SCLC. PATIENTS AND METHODS: Eligible patients with incurable or metastatic SCLC, which was advanced or recurrent since the last antitumor therapy, received atezolizumab 15 mg/kg or 1200 mg intravenously every 3 weeks for 16 cycles or until loss of clinical benefit. The primary endpoint was safety. Efficacy and biomarkers of antitumor activity were also assessed. RESULTS: Seventeen patients were enrolled. Any-grade and grade ≥3 treatment-related adverse events (TRAEs) occurred in 11 (64.7%) and 5 (29.4%) patients, respectively. The most common any-grade TRAE was fatigue (4 patients [23.5%]). Partial response to atezolizumab was achieved in 1 patient (5.9%) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1), and 3 (17.6%) per immune-related response criteria (irRC). Durations of response were 2.8 to > 45.7 months. Median investigator-assessed progression-free survival (PFS) per RECIST v1.1 and irRC was 1.5 (95% confidence interval [CI], 1.2-2.7) and 2.9 (95% CI, 1.2-6.1) months, respectively. Median overall survival (OS) was 5.9 months (95% CI, 4.3-12.6). Patients with high (≥ median expression) T-effector gene signature and PD-L1 mRNA expression appeared to show a trend toward improved PFS (per irRC) and OS. CONCLUSION: Atezolizumab was generally well tolerated and exhibited antitumor activity in a small cohort of patients with relapsed/refractory SCLC.

Dendritic cells dictate responses to PD-L1 blockade cancer immunotherapy.

PD-L1/PD-1 blocking antibodies have demonstrated therapeutic efficacy across a range of human cancers. Extending this benefit to a greater number of patients, however, will require a better understanding of how these therapies instigate anticancer immunity. Although the PD-L1/PD-1 axis is typically associated with T cell function, we demonstrate here that dendritic cells (DCs) are an important target of PD-L1 blocking antibody. PD-L1 binds two receptors, PD-1 and B7.1 (CD80). PD-L1 is expressed much more abundantly than B7.1 on peripheral and tumor-associated DCs in patients with cancer. Blocking PD-L1 on DCs relieves B7.1 sequestration in cis by PD-L1, which allows the B7.1/CD28 interaction to enhance T cell priming. In line with this, in patients with renal cell carcinoma or non-small cell lung cancer treated with atezolizumab (PD-L1 blockade), a DC gene signature is strongly associated with improved overall survival. These data suggest that PD-L1 blockade reinvigorates DC function to generate potent anticancer T cell immunity.