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Purpose of Review: Mantle cell lymphoma (MCL) is a heterogenous disease with a variety of morphologic and genetic features, some of which are associated with high risk disease. Here we critically analyze the current state of the understanding of MCL's biology and its implications in therapy, with a focus on chemotherapy-free and targeted therapy regimens., Recent Findings: Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin's lymphoma, defined by a hallmark chromosomal translocation t(11;14) which leads to constitutive expression of cyclin D1. Recent discoveries in the biology of MCL have identified a number of factors, including TP53 mutations and complex karyotype, that lead to unresponsiveness to traditional chemoimmunotherapy and poor outcomes. Bruton tyrosine kinase inhibitors, BH3-mimetics and other novel agents thwart survival of the neoplastic B-cells in a manner independent of high-risk mutations and have shown promising activity in relapsed/refractory MCL. These therapies are being investigated in the frontline setting, while optimal responses to chemotherapy-free regimens, particularly in high-risk disease, might require combination approaches. High-risk MCL does not respond well to chemoimmunotherapy. Targeted agents are highly active in the relapsed refractory setting and show promise in high-risk disease. Novel approaches may soon replace the current standard of care in both relapsed and frontline settings.

The pathogenesis of acute myeloid leukemia (AML) involves serial acquisition of mutations controlling several cellular processes, requiring combination therapies affecting key downstream survival nodes in order to treat the disease effectively. The BCL2 selective inhibitor venetoclax has potent anti-leukemia efficacy; however, resistance can occur due to its inability to inhibit MCL1, which is stabilized by the MAPK pathway. In this study, we aimed to determine the anti-leukemia efficacy of concomitant targeting of the BCL2 and MAPK pathways by venetoclax and the MEK1/2 inhibitor cobimetinib, respectively. The combination demonstrated synergy in seven of 11 AML cell lines, including those resistant to single agents, and showed growth-inhibitory activity in over 60% of primary samples from patients with diverse genetic alterations. The combination markedly impaired leukemia progenitor functions, while maintaining normal progenitors. Mass cytometry data revealed that BCL2 protein is enriched in leukemia stem/progenitor cells, primarily in venetoclax-sensitive samples, and that cobimetinib suppressed cytokine-induced pERK and pS6 signaling pathways. Through proteomic profiling studies, we identified several pathways inhibited downstream of MAPK that contribute to the synergy of the combination. In OCI-AML3 cells, the combination downregulated MCL1 protein levels and disrupted both BCL2:BIM and MCL1:BIM complexes, releasing BIM to induce cell death. RNA sequencing identified several enriched pathways, including MYC, mTORC1, and p53 in cells sensitive to the drug combination. In vivo , the venetoclax-cobimetinib combination reduced leukemia burden in xenograft models using genetically engineered OCI-AML3 and MOLM13 cells. Our data thus provide a rationale for combinatorial blockade of MEK and BCL2 pathways in AML., (Copyright© 2020 Ferrata Storti Foundation.)

Non-small cell lung cancer (NSCLC) patients with c-MET dysregulation may benefit from c-MET inhibitors therapy as inhibition of c-MET activity has emerged as a therapeutic approach against this disease. Although several c-MET inhibitors have been evaluated in multiple clinical trials in lung cancer, their benefits so far have been modest. Thus, furthering our understanding of the mechanisms contributing to the lack of success of c-MET inhibitors in clinical trials is essential toward the development of rational and effective combination strategies. Here we show that exposure of NCSLC cell lines to c-MET inhibitor tivantinib increases their expression of PD-L1, which in turn causes cells to become more resistant to T-cell killing. Mechanistically, inhibition of c-MET suppresses p-GSK3β, leading to the stabilization of PD-L1 similar to that observed in liver cancer cells. Collectively, our findings suggest a potential crosstalk between c-MET inhibition and immune escape and provide a rationale for the combination therapy of c-MET inhibitors and immune checkpoint blockade in NSCLC., Competing Interests: None., (AJCR Copyright © 2020.)

Background & Aims: Inhibitors of MET have not produced satisfactory outcomes in trials of patients with liver cancer. We investigated the mechanisms of liver tumor resistance to MET inhibitors in mice., Methods: We tested the effects of MET inhibitors tivantinib and capmatinib in the mouse hepatocellular carcinoma (HCC) cell line HCA-1 and in immune-competent and immunodeficient mice with subcutaneous tumors grown from this cell line. Tumors were collected from mice and tumor cells were analyzed by time-of-flight mass cytometry. We used short hairpin RNAs to weaken expression of MET in Hep3B, SK-HEP-1, HA59T, and HA22T liver cancer cell lines and analyzed cells by immunoblot, immunofluorescence, and immunoprecipitation assays. Mass spectrometry was used to assess interactions between MET and glycogen synthase kinase 3β (GSK3B), and GSK3B phosphorylation, in liver cancer cell lines. C57/BL6 mice with orthotopic tumors grown from Hep1-6 cells were given combinations of capmatinib or tivantinib and antibodies against programmed cell death 1 (PDCD1; also called PD1); tumors were collected and analyzed by immunofluorescence. We analyzed 268 HCCsamples in a tissue microarray by immunohistochemistry., Results: Exposure of liver cancer cell lines to MET inhibitors increased their expression of PD ligand 1 (PDL1) and inactivated cocultured T cells. MET phosphorylated and activated GSK3B at tyrosine 56, which decreased the expression of PDL1 by liver cancer cells. In orthotopic tumors grown in immune-competent mice, MET inhibitors decreased the antitumor activity of T cells. However, addition of anti-PD1 decreased orthotopic tumor growth and prolonged survival of mice compared with anti-PD1 or MET inhibitors alone. Tissue microarray analysis of HCC samples showed an inverse correlation between levels of MET and PDL1 and a positive correlation between levels of MET and phosphorylated GSK3B., Conclusions: In studies of liver cancer cell lines and mice with orthotopic tumors, MET mediated phosphorylation and activated GSK3B, leading to decreased expression of PDL1. Combined with a MET inhibitor, anti-PD1 and anti-PDL1 produced additive effect to slow growth of HCCs in mice., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Some patients with chronic myeloid leukemia (CML) have a history of previous malignancies. To the authors' knowledge, outcomes for CML diagnosed in these patients have not been well described. The current study was conducted to determine the outcome of patients with CML and a history of prior malignancies., Methods: The current study included patients who were enrolled in clinical trials of tyrosine kinase inhibitors as initial therapy for CML in chronic phase from July 2000 to January 2014., Results: Of the 630 patients with CML who were treated with frontline tyrosine kinase inhibitors, 626 had a known prior malignancy status. Of these, 45 patients (7%) had a prior malignancy other than nonmelanoma skin cancer whereas 17 patients (3%) had a history of nonmelanoma skin cancers alone. Characteristics of CML were similar between the patients with no prior malignancy, those with a prior malignancy, and those with nonmelanoma skin cancer. Patients with a prior malignancy were found to have an older median age compared with the other 2 groups. The most common prior malignancies were nonmelanoma skin cancer in 20 patients, breast cancer in 11 patients, melanoma in 7 patients, prostate cancer in 6 patients, and colorectal cancer in 5 patients. With regard to CML, the event-free survival, transformation-free survival, and failure-free survival rates were found to be similar between the groups. There was a statistically significantly decreased survival in the group with a prior malignancy versus the group with no prior malignancy versus the group with nonmelanoma skin cancer. In a multivariate analysis, advanced age and an elevated creatinine level were found to be associated with worse survival after a diagnosis of CML., Conclusions: Patients with CML with a history of prior malignancies appear to have the same excellent outcome as patients with no prior malignancies. In the few instances in which concomitant therapy for other malignancies was required during therapy with tyrosine kinase inhibitors, this was able to be accomplished without significant toxicity. Cancer 2017;123:609-616. © 2016 American Cancer Society., Competing Interests: of conflicts of interest: J.C. has received research grants from Novartis, BMS, Ariad, Teva and Pfizer. J.C. is a consultant for Novartis, BMS, Pfizer, and Ariad. The remaining authors declare no competing financial interests., (© 2016 American Cancer Society.)