No effective systemic treatment is available for patients with unresectable, recurrent, or metastatic mucoepidermoid carcinoma (MEC), the most common salivary gland malignancy. MEC is frequently associated with a t(11;19)(q14-21;p12-13) translocation that creates a CRTC1-MAML2 fusion gene. The CRTC1-MAML2 fusion exhibited transforming activity in vitro; however, whether it serves as an oncogenic driver for MEC establishment and maintenance in vivo remains unknown. Here, we show that doxycycline-induced CRTC1-MAML2 knockdown blocked the growth of established MEC xenografts, validating CRTC1-MAML2 as a therapeutic target. We further generated a conditional transgenic mouse model and observed that Cre-induced CRTC1-MAML2 expression caused 100% penetrant formation of salivary gland tumors resembling histological and molecular characteristics of human MEC. Molecular analysis of MEC tumors revealed altered p16-CDK4/6-RB pathway activity as a potential cooperating event in promoting CRTC1-MAML2–induced tumorigenesis. Cotargeting of aberrant p16-CDK4/6-RB signaling and CRTC1-MAML2 fusion–activated AREG/EGFR signaling with the respective CDK4/6 inhibitor Palbociclib and EGFR inhibitor Erlotinib produced enhanced antitumor responses in vitro and in vivo. Collectively, this study provides direct evidence for CRTC1-MAML2 as a key driver for MEC development and maintenance and identifies a potentially novel combination therapy with FDA-approved EGFR and CDK4/6 inhibitors as a potential viable strategy for patients with MEC.

Bromodomain-containing protein 9 (BRD9), an essential component of the SWI/SNF chromatin remodeling complex termed ncBAF, has been established as a therapeutic target in a subset of sarcomas and leukemias. Here, we used novel small molecule inhibitors and degraders along with RNA interference to assess the dependency on BRD9 in the context of diverse hematological malignancies, including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), and multiple myeloma (MM) model systems. Following depletion of BRD9 protein, AML cells undergo terminal differentiation, whereas apoptosis was more prominent in ALL and MM. RNA-seq analysis of acute leukemia and MM cells revealed both unique and common signaling pathways affected by BRD9 degradation, with common pathways including those associated with regulation of inflammation, cell adhesion, DNA repair and cell cycle progression. Degradation of BRD9 potentiated the effects of several chemotherapeutic agents and targeted therapies against AML, ALL, and MM. Our findings support further development of therapeutic targeting of BRD9, alone or combined with other agents, as a novel strategy for acute leukemias and MM.

The aim of the present study was to assess the efficacy of adjuvant chemotherapy (AC) in patients with esophageal squamous cell carcinoma (ESCC) treated with definitive chemoradiotherapy (CRT). The clinical data of patients with ESCC treated with chemoradiotherapy with or without AC were collected and retrospectively reviewed. The overall survival (OS), locoregional failure-free survival (LFFS) and distant failure-free survival (DFFS) rates were analyzed statistically. A total of 187 patients fulfilled the inclusion criteria, 98 of whom were treated with CRT-alone, while 89 were treated with CRT-AC. Patient characteristics did not significantly differ between the CRT-alone and CRT-AC groups, with the exception of sex and the number of cycles of concurrent chemotherapy. Following CRT, 50 patients achieved complete response (CR), 67 had partial response (PR), 63 patients maintained stable disease (SD) and 7 developed progression of disease (PD). The OS, LFFS and DFFS at 1, 2 and 5 years for the entire cohort were 67.5, 41.4 and 27.2%; 68.7, 57.9 and 52.4%; and 78.5, 68.9 and 63.9%, respectively. The clinical N-stage, M-stage, and short-term response to CRT were identified as significant factors that influenced patient prognosis. No significant differences in OS, LFFS or DFFS were observed between the CRT-alone and CRT-AC groups for the entire cohort and for clinical N-stage, clinical M-stage and short-term response subgroups. The short-term response to CRT and the tumor clinical stage were significant prognosis factors for patients with ESCC treated with CRT. With current chemotherapy regimens, AC did not improve survival for patients with ESCC treated with CRT. The retrospective nature of the current study serves as a limitation; thus, further clinical trials are required to evaluate the efficacy of AC in patients with ESCC treated with CRT.

Mucoepidermoid carcinoma (MEC) is the most common type of salivary gland cancers and patients with advanced, metastatic, and recurrent MECs have limited therapeutic options and poor treatment outcomes. MEC is commonly associated with a chromosomal translocation t(11;19) (q14-21;p12-13) that encodes the CRTC1-MAML2 oncogenic fusion. The CRTC1-MAML2 fusion is required for MEC growth in part through inducing autocrine AREG-EGFR signaling. Growing evidence suggests that MEC malignancy is maintained by cancer stem-like cells. In this study, we aimed to determine critical signaling for maintaining MEC stem-like cells and the effect of combined targeting of stem cell signaling and CRTC1-MAML2-induced EGFR signaling on blocking MEC growth. First, we evaluated the significance of Notch signaling in regulating MEC stem-like cells. Aberrantly activated Notch signaling was detected in human fusion-positive MEC cells. The inhibition of Notch signaling with genetic or pharmacological inhibitors reduced oncosphere formation and ALDH-bright population in vitro and blocked the growth of MEC xenografts in vivo. Next, we investigated the effect of co-targeting Notch signaling and EGFR signaling, and observed enhanced inhibition on MEC growth in vivo. Collectively, this study identified a critical role of Notch signaling in maintaining MEC stem-like cells and tumor growth, and revealed a novel approach of co-targeting Notch and EGFR signaling as a potential effective anti-MEC treatment.