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Growing evidence suggests that microbes can influence the efficacy of cancer therapies. By studying colon cancer models, we found that bacteria can metabolize the chemotherapeutic drug gemcitabine (2′,2′-difluorodeoxycytidine) into its inactive form, 2′,2′-difluorodeoxyuridine. Metabolism was dependent on the expression of a long isoform of the bacterial enzyme cytidine deaminase (CDDL), seen primarily in Gammaproteobacteria. In a colon cancer mouse model, gemcitabine resistance was induced by intratumor Gammaproteobacteria, dependent on bacterial CDDL expression, and abrogated by cotreatment with the antibiotic ciprofloxacin. Gemcitabine is commonly used to treat pancreatic ductal adenocarcinoma (PDAC), and we hypothesized that intratumor bacteria might contribute to drug resistance of these tumors. Consistent with this possibility, we found that of the 113 human PDACs that were tested, 86 (76%) were positive for bacteria, mainly Gammaproteobacteria.

Few standard treatment options are available for patients with metastatic sarcomas. We did this trial to evaluate the efficacy, safety, and changes in the tumour microenvironment for durvalumab, an anti-PD-L1 drug, and tremelimumab, an anti-CTLA-4 drug, across multiple sarcoma subtypes. In this single-centre phase 2 trial, done at The University of Texas MD Anderson Cancer Center (Houston, TX USA), patients aged 18 years or older with advanced or metastatic sarcoma with an Eastern Cooperative Oncology Group performance status of 0 or 1 who had received at least one previous line of systemic therapy were enrolled in disease subtype-specific groups (liposarcoma, leiomyosarcoma, angiosarcoma, undifferentiated pleomorphic sarcoma, synovial sarcoma, osteosarcoma, alveolar soft-part sarcoma, chordoma, and other sarcomas). Patients received 1500 mg intravenous durvalumab and 75 mg intravenous tremelimumab for four cycles, followed by durvalumab alone every 4 weeks for up to 12 months. The primary endpoint was progression-free survival at 12 weeks in the intention-to-treat population (all patients who received at least one dose of treatment). Safety was also analysed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02815995, and is completed. Between Aug 17, 2016, and April 9, 2018, 62 patients were enrolled, of whom 57 (92%) received treatment and were included in the intention-to-treat population. With a median follow-up of 37·2 months (IQR 1·8–10·1), progression-free survival at 12 weeks was 49% (95% CI 36–61). 21 grade 3–4 treatment-related adverse events were reported, the most common of which were increased lipase (four [7%] of 57 patients), colitis (three [5%] patients), and pneumonitis (three [5%] patients). Nine (16%) patients had a treatment related serious adverse event. One patient had grade 5 pneumonitis and colitis. The combination of durvalumab and tremelimumab is an active treatment regimen for advanced or metastatic sarcoma and merits evaluation in specific subsets in future trials. AstraZeneca.

Trever Bivona and colleagues show that the Hippo pathway effector YAP promotes resistance to RAF and MEK inhibitor therapy in multiple types of BRAF -mutant tumors. The findings suggest that combined suppression of YAP and RAF-MEK signaling might enhance treatment response and prevent drug resistance. Resistance to RAF- and MEK-targeted therapy is a major clinical challenge 1 , 2 , 3 , 4 . RAF and MEK inhibitors are initially but only transiently effective in some but not all patients with BRAF gene mutation and are largely ineffective in those with RAS gene mutation because of resistance 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 . Through a genetic screen in BRAF-mutant tumor cells, we show that the Hippo pathway effector YAP (encoded by YAP1 ) acts as a parallel survival input to promote resistance to RAF and MEK inhibitor therapy. Combined YAP and RAF or MEK inhibition was synthetically lethal not only in several BRAF-mutant tumor types but also in RAS-mutant tumors. Increased YAP in tumors harboring BRAF V600E was a biomarker of worse initial response to RAF and MEK inhibition in patients, establishing the clinical relevance of our findings. Our data identify YAP as a new mechanism of resistance to RAF- and MEK-targeted therapy. The findings unveil the synthetic lethality of combined suppression of YAP and RAF or MEK as a promising strategy to enhance treatment response and patient survival.

Treatment with anti-PD-1 and anti-PD-L1 therapies has shown durable clinical benefit in non-small cell lung cancer (NSCLC). However, patients with NSCLC with epidermal growth factor receptor (EGFR) mutations do not respond as well to treatment as patients without an EGFR mutation. We show that EGFR-mutated NSCLC expressed higher levels of CD73 compared with EGFR WT tumors and that CD73 expression was regulated by EGFR signaling. EGFR-mutated cell lines were significantly more resistant to T cell killing compared with WT cell lines through suppression of T cell proliferation and function. In a xenograft mouse model of EGFR-mutated NSCLC, neither anti-PD-L1 nor anti-CD73 antibody alone inhibited tumor growth compared with the isotype control. In contrast, the combination of both antibodies significantly inhibited tumor growth, increased the number of tumor-infiltrating CD8+ T cells, and enhanced IFN-γ and TNF-α production of these T cells. Consistently, there were increases in gene expression that corresponded to inflammation and T cell function in tumors treated with the combination of anti-PD-L1 and anti-CD73. Together, these results further support the combination of anti-CD73 and anti-PD-L1 therapies in treating EGFR-mutated NSCLC, while suggesting that increased T cell activity may play a role in response to therapy.

Melanoma is the deadliest form of skin cancer and has an incidence that is rising faster than any other solid tumor. Metastatic melanoma treatment has considerably progressed in the past five years with the introduction of targeted therapy （BRAF and MEK inhibitors） and immune checkpoint blockade （anti-CTLA4, anti-PD-1, and anti-PD-L1）. However, each treatment modality has limitations. Treatment with targeted therapy has been associated with a high response rate, but with short-term responses. Conversely, treatment with immune checkpoint blockade has a lower response rate, but with long- term responses. Targeted therapy affects antitumor immunity, and synergy may exist when targeted therapy is combined with immunotherapy, This article presents a brief review of the rationale and evidence for the potential synergy between targeted therapy and immune checkpoint blockade. Challenges and directions for future studies are also proposed.

A newer generation of anti-cancer drugs targeting underlying somatic genetic driver events have resulted in high single-agent or single-pathway response rates in selected patients, but few patients achieve complete responses and a sizeable fraction of patients relapse within a year. Thus, there is a pressing need for identification of combinations of targeted agents which induce more complete responses and prevent disease progression. We describe the results of a combination screen of an unprecedented scale in mammalian cells performed using a collection of targeted, clinically tractable agents across a large panel of melanoma cell lines. We find that even the most synergistic drug pairs are effective only in a discrete number of cell lines, underlying a strong context dependency for synergy, with strong, widespread synergies often corresponding to non-specific or off-target drug effects such as multidrug resistance protein 1 (MDR1) transporter inhibition. We identified drugs sensitizing cell lines that are BRAFV600E mutant but intrinsically resistant to BRAF inhibitor PLX4720, including the vascular endothelial growth factor receptor/kinase insert domain receptor (VEGFR/KDR) and platelet derived growth factor receptor (PDGFR) family inhibitor cediranib. The combination of cediranib and PLX4720 induced apoptosis in vitro and tumor regression in animal models. This synergistic interaction is likely due to engagement of multiple receptor tyrosine kinases (RTKs), demonstrating the potential of drug- rather than gene-specific combination discovery approaches. Patients with elevated biopsy KDR expression showed decreased progression free survival in trials of mitogen-activated protein kinase (MAPK) kinase pathway inhibitors. Thus, high-throughput unbiased screening of targeted drug combinations, with appropriate library selection and mechanistic follow-up, can yield clinically-actionable drug combinations.

Approaches to prolong responses to BRAF targeting drugs in melanoma patients are challenged by phenotype heterogeneity. Melanomas of a “MITF‐high” phenotype usually respond well to BRAF inhibitor therapy, but these melanomas also contain subpopulations of the de novo resistance “AXL‐high” phenotype. > 50% of melanomas progress with enriched “AXL‐high” populations, and because AXL is linked to de‐differentiation and invasiveness avoiding an “AXL‐high relapse” is desirable. We discovered that phenotype heterogeneity is supported during the response phase of BRAF inhibitor therapy due to MITF‐induced expression of endothelin 1 (EDN1). EDN1 expression is enhanced in tumours of patients on treatment and confers drug resistance through ERK re‐activation in a paracrine manner. Most importantly, EDN1 not only supports MITF‐high populations through the endothelin receptor B (EDNRB), but also AXL‐high populations through EDNRA, making it a master regulator of phenotype heterogeneity. Endothelin receptor antagonists suppress AXL‐high‐expressing cells and sensitize to BRAF inhibition, suggesting that targeting EDN1 signalling could improve BRAF inhibitor responses without selecting for AXL‐high cells. Synopsis Melanoma heterogeneity challenges durable responses to BRAF targeting. During BRAF‐inhibitor treatment endothelin‐1 (EDN1) supports phenotype heterogeneity thereby allowing outgrowth of resistant cells. Blocking EDN1 signalling can overcome this support. Phenotype heterogeneity in melanoma is characterised by MITF‐high and AXL‐high subpopulations. Tumours enriched in AXL‐high subpopulations are resistant to BRAF‐inhibitor treatment. BRAF inhibitor‐responding tumours contain a small population of AXL‐high cells. Treatment with BRAF inhibitor induces upregulation of EDN1, and paracrine acting EDN1 supports the outgrowth of AXL‐high subpopulations. Treatment with EDN receptor (EDNR) antagonists overcomes paracrine EDN1 signalling and prolongs BRAF‐inhibitor responses. Graphical Abstract Melanoma heterogeneity challenges durable responses to BRAF targeting. During BRAF‐inhibitor treatment endothelin‐1 (EDN1) supports phenotype heterogeneity thereby allowing outgrowth of resistant cells. Blocking EDN1 signalling can overcome this support.

BackgroundMEDI9197 is an intratumorally administered toll-like receptor 7 and 8 agonist. In mice, MEDI9197 modulated antitumor immune responses, inhibited tumor growth and increased survival. This first-time-in-human, phase 1 study evaluated MEDI9197 with or without the programmed cell death ligand-1 (PD-L1) inhibitor durvalumab and/or palliative radiation therapy (RT) for advanced solid tumors.Patients and methodsEligible patients had at least one cutaneous, subcutaneous, or deep-seated lesion suitable for intratumoral (IT) injection. Dose escalation used a standard 3+3 design. Patients received IT MEDI9197 0.005–0.055 mg with or without RT (part 1), or IT MEDI9197 0.005 or 0.012 mg plus durvalumab 1500 mg intravenous with or without RT (part 3), in 4-week cycles. Primary endpoints were safety and tolerability. Secondary endpoints included pharmacokinetics, pharmacodynamics, and objective response based on Response Evaluation Criteria for Solid Tumors version 1.1. Exploratory endpoints included tumor and peripheral biomarkers that correlate with biological activity or predict response.ResultsFrom November 2015 to March 2018, part 1 enrolled 35 patients and part 3 enrolled 17 patients; five in part 1 and 2 in part 3 received RT. The maximum tolerated dose of MEDI9197 monotherapy was 0.037 mg, with dose-limiting toxicity (DLT) of cytokine release syndrome in two patients (one grade 3, one grade 4) and 0.012 mg in combination with durvalumab 1500 mg with DLT of MEDI9197-related hemorrhagic shock in one patient (grade 5) following liver metastasis rupture after two cycles of MEDI9197. Across parts 1 and 3, the most frequent MEDI9197-related adverse events (AEs) of any grade were fever (56%), fatigue (31%), and nausea (21%). The most frequent MEDI9197-related grade ≥3 events were decreased lymphocytes (15%), neutrophils (10%), and white cell counts (10%). MEDI9197 increased tumoral CD8+ and PD-L1+ cells, inducing type 1 and 2 interferons and Th1 response. There were no objective clinical responses; 10 patients in part 1 and 3 patients in part 3 had stable disease ≥8 weeks.ConclusionIT MEDI9197 was feasible for subcutaneous/cutaneous lesions but AEs precluded its use in deep-seated lesions. Although no patients responded, MEDI9197 induced systemic and intratumoral immune activation, indicating potential value in combination regimens in other patient populations.Trial registration number NCT02556463.

While response rates to BRAF inhibitiors (BRAFi) are high, disease progression emerges quickly. One strategy to delay the onset of resistance is to target anti-apoptotic proteins such as BCL-2, known to be associated with a poor prognosis. We analyzed BCL-2 family member expression levels of 34 samples from 17 patients collected before and 10 to 14 days after treatment initiation with either vemurafenib or dabrafenib/trametinib combination. The observed changes in mRNA and protein levels with BRAFi treatment led us to hypothesize that combining BRAFi with a BCL-2 inhibitor (the BH3-mimetic navitoclax) would improve outcome. We tested this hypothesis in cell lines and in mice. Pretreatment mRNA levels of BCL-2 negatively correlated with maximal tumor regression. Early increases in mRNA levels were seen in BIM, BCL-XL, BID and BCL2-W, as were decreases in MCL-1 and BCL2A. No significant changes were observed with BCL-2. Using reverse phase protein array (RPPA), significant increases in protein levels were found in BIM and BID. No changes in mRNA or protein correlated with response. Concurrent BRAF (PLX4720) and BCL2 (navitoclax) inhibition synergistically reduced viability in BRAF mutant cell lines and correlated with down-modulation of MCL-1 and BIM induction after PLX4720 treatment. In xenograft models, navitoclax enhanced the efficacy of PLX4720. The combination of a selective BRAF inhibitor with a BH3-mimetic promises to be an important therapeutic strategy capable of enhancing the clinical efficacy of BRAF inhibition in many patients that might otherwise succumb quickly to de novo resistance. Trial registrations: ClinicalTrials.gov NCT01006980; ClinicalTrials.gov NCT01107418; ClinicalTrials.gov NCT01264380; ClinicalTrials.gov NCT01248936; ClinicalTrials.gov NCT00949702; ClinicalTrials.gov NCT01072175.

Background CD73 and CD39, key components of the adenosine axis, are expressed in multiple malignancies; the impact of standard-of-care treatment on their expression and antitumor immunity in esophageal squamous cell carcinoma (ESCC) remains unclear. We evaluated the adenosine axis in the context of neoadjuvant therapy received and its relationship to immune markers in ESCC tumor samples. Methods Samples from patients who underwent surgical resection at the National Cancer Center Hospital, Tokyo, Japan, between January 2002 and July 2019 following no neoadjuvant therapy (n = 55; treatment-naïve), chemotherapy (n = 200), or chemoradiotherapy (CRT; n = 20) were immunohistochemically stained for CD73, CD39, PD-L1, FoxP3, and CD8; markers were quantified across tumor microenvironment (TME) compartments. Results Median CD73 TME expression was lower in the treatment-naïve (2.8%) versus chemotherapy (7.2%; p < 0.0001) and CRT (6.4%; p < 0.01) cohorts, most profoundly in the stroma (median 4.1% vs 9.4% [p < 0.0001] and 8.1% [p < 0.01]). Median intraepithelial CD8-positive cell density was higher in the treatment-naïve (200.7 cells/mm 2 ) versus chemotherapy (93.9 cells/mm 2 ; p < 0.0001) and CRT (30.5 cells/mm 2 ; p < 0.001) cohorts. Three-year recurrence-free survival (RFS) was 73.0%, 58.0%, and 30.0%, and 3-year overall survival (OS) was 78.2%, 71.4%, and 33.5%, in the treatment-naïve, chemotherapy, and CRT cohorts, respectively. High versus low CD73 TME expression was prognostic for longer RFS (treatment-naïve cohort: hazard ratio [HR] 0.16, 95% confidence interval [CI] 0.05–0.58, p = 0.0014; chemotherapy cohort: HR 0.52, 95% CI 0.34–0.78, p = 0.0012) and OS. Conclusions These translational data demonstrating higher CD73 expression in tumors after neoadjuvant chemotherapy or CRT support potential combination strategies with CD73-targeted treatment in ESCC.