Salvia Jain

Individualized vaccination of AML patients in remission is associated with induction of antileukemia immunity and prolonged remissions

A personalized DC/AML fusion cell vaccine promotes the expansion of leukemia-specific T cells and prolonged remission in patients. Immune cells join leukemia then beat it Acute myeloid leukemia (AML) is an aggressive hematologic cancer. The only curative treatment available for this disease is hematopoietic stem cell transplantation, which can result in donor immune cells helping to eradicate the cancer. Unfortunately, this procedure is not always effective and is itself associated with numerous complications and risk of death. Rosenblatt et al. have identified a potentially better way to stimulate an immune response against AML by fusing patients’ own leukemia cells with dendritic cells. The resulting fusion cells were very effective at presenting tumor antigens to T cells, resulting in a strong antitumor T cell response and prolonged survival in human patients. We developed a personalized cancer vaccine in which patient-derived acute myeloid leukemia (AML) cells are fused with autologous dendritic cells, generating a hybridoma that potently stimulates broad antitumor responses. We report results obtained from the first 17 AML patients, who achieved remission after chemotherapy and were then serially vaccinated to target minimal residual disease and prevent relapse. Vaccination was well tolerated and induced inflammatory responses at the site of administration, characterized by the dense infiltration of T cells. Vaccination was also associated with a marked rise in circulating T cells recognizing whole AML cells and leukemia-specific antigens that persisted for more than 6 months. Twelve of 17 vaccinated patients (71%; 90% confidence interval, 52 to 89%) remain alive without recurrence at a median follow-up of 57 months. The results demonstrate that personalized vaccination of AML patients in remission induces the expansion of leukemia-specific T cells and may be protective against disease relapse.

Mucin 1 is a potential therapeutic target in cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is an aggressive neoplasm with limited treatments for patients with advanced disease. The mucin 1 C-terminal subunit (MUC1-C) oncoprotein plays a critical role in regulating cell proliferation, apoptosis, and protection from cytotoxic injury mediated by reactive oxygen species (ROS). Although CTCL cells exhibit resistance to ROS-induced apoptosis, the expression and functional significance of MUC1 in CTCL have not been previously investigated. Present studies demonstrate that MUC1-C is overexpressed in CTCL cell lines and primary CTCL cells but is absent in resting T cells from healthy donors and B-cell lymphoma cells. We have developed a cell-penetrating peptide that disrupts homodimerization of the MUC1-C subunit necessary for its nuclear translocation and downstream signaling. We show that treatment of CTCL cells with the MUC1-C inhibitor is associated with downregulation of the p53-inducible regulator of glycolysis and apoptosis and decreases in reduced NAD phosphate and glutathione levels. In concert with these results, targeting MUC1-C in CTCL cells increased ROS and, in turn, induced ROS-mediated late apoptosis/necrosis. Targeting MUC1-C in CTCL tumor xenograft models demonstrated significant decreases in disease burden. These findings indicate that MUC1-C maintains redox balance in CTCL cells and is thereby a novel target for the treatment of patients with CTCL.

MUC1 inhibition leads to decrease in PD-L1 levels via upregulation of miRNAs

The PD-L1/PD-1 pathway is a critical component of the immunosuppressive tumor microenvironment in acute myeloid leukemia (AML), but little is known about its regulation. We investigated the role of the MUC1 oncoprotein in modulating PD-L1 expression in AML. Silencing of MUC1 in AML cell lines suppressed PD-L1 expression without a decrease in PD-L1 mRNA levels, suggesting a post-transcriptional mechanism of regulation. We identified the microRNAs miR-200c and miR-34a as key regulators of PD-L1 expression in AML. Silencing of MUC1 in AML cells led to a marked increase in miR-200c and miR-34a levels, without changes in precursor microRNA, suggesting that MUC1 might regulate microRNA-processing. MUC1 signaling decreased the expression of the microRNA-processing protein DICER, via the suppression of c-Jun activity. NanoString (Seattle, WA, USA) array of MUC1-silenced AML cells demonstrated an increase in the majority of probed microRNAs. In an immunocompetent murine AML model, targeting of MUC1 led to a significant increase in leukemia-specific T cells. In concert, targeting MUC1 signaling in human AML cells resulted in enhanced sensitivity to T-cell-mediated lysis. These findings suggest MUC1 is a critical regulator of PD-L1 expression via its effects on microRNA levels and represents a potential therapeutic target to enhance anti-tumor immunity.

Preclinical Pharmacologic Evaluation of Pralatrexate and Romidepsin Confirms Potent Synergy of the Combination in a Murine Model of Human T-cell Lymphoma

Purpose: T-cell lymphomas (TCL) are aggressive diseases, which carry a poor prognosis. The emergence of new drugs for TCL has created a need to survey these agents in a rapid and reproducible fashion, to prioritize combinations which should be prioritized for clinical study. Mouse models of TCL that can be used for screening novel agents and their combinations are lacking. Developments in noninvasive imaging modalities, such as surface bioluminescence (SBL) and three-dimensional ultrasound (3D-US), are challenging conventional approaches in xenograft modeling relying on caliper measurements. The recent approval of pralatrexate and romidepsin creates an obvious combination that could produce meaningful activity in TCL, which is yet to be studied in combination. Experimental Design: High-throughput screening and multimodality imaging approach of SBL and 3D-US in a xenograft NOG mouse model of TCL were used to explore the in vitro and in vivo activity of pralatrexate and romidepsin in combination. Corresponding mass spectrometry–based pharmacokinetic and immunohistochemistry-based pharmacodynamic analyses of xenograft tumors were performed to better understand a mechanistic basis for the drug:drug interaction. Results: In vitro, pralatrexate and romidepsin exhibited concentration-dependent synergism in combination against a panel of TCL cell lines. In a NOG murine model of TCL, the combination of pralatrexate and romidepsin exhibited enhanced efficacy compared with either drug alone across a spectrum of tumors using complementary imaging modalities, such as SBL and 3D-US. Conclusions: Collectively, these data strongly suggest that the combination of pralatrexate and romidepsin merits clinical study in patients with TCLs. Clin Cancer Res; 21(9); 2096–106. ©2015 AACR.

MUC1 mediated induction of myeloid-derived suppressor cells in patients with acute myeloid leukemia.

Myeloid-derived suppressor cells (MDSCs) play a critical role in promoting immune tolerance and disease growth. The mechanism by which tumor cells evoke the expansion of MDSCs in acute myeloid leukemia (AML) has not been well described. We have demonstrated that patients with AML exhibit increased presence of MDSCs in their peripheral blood, in comparison with normal controls. Cytogenetic studies demonstrated that MDSCs in patients with AML may be derived from leukemic or apparently normal progenitors. Engraftment of C57BL/6 mice with TIB-49 AML led to an expansion of CD11b+ Gr1+ MDSCs in bone marrow and spleen. Coculture of the AML cell lines MOLM-4, THP-1 or primary AML cells with donor peripheral blood mononuclear cells elicited a cell contact-dependent expansion of MDSCs. MDSCs were suppressive of autologous T-cell responses as evidenced by reduced T-cell proliferation and a switch from a Th1 to a Th2 phenotype. We hypothesized that the expansion of MDSCs in AML is accomplished by tumor-derived extracellular vesicles (EVs). Using tracking studies, we demonstrated that AML EVs are taken-up myeloid progenitor cells, resulting in the selective proliferation of MDSCs in comparison with functionally competent antigen-presenting cells. The MUC1 oncoprotein was subsequently identified as the critical driver of EV-mediated MDSC expansion. MUC1 induces increased expression of c-myc in EVs that induces proliferation in the target MDSC population via downstream effects on cell cycle proteins. Moreover, we demonstrate that the microRNA miR34a acts as the regulatory mechanism by which MUC1 drives c-myc expression in AML cells and EVs.

Bone marrow stroma protects myeloma cells from cytotoxic damage via induction of the oncoprotein MUC1.

Multiple myeloma (MM) is a lethal haematological malignancy that arises in the context of a tumour microenvironment that promotes resistance to apoptosis and immune escape. In the present study, we demonstrate that co‐culture of MM cells with stromal cells results in increased resistance to cytotoxic and biological agents as manifested by decreased rates of cell death following exposure to alkylating agents and the proteosome inhibitor, bortezomib. To identify the mechanism of increased resistance, we examined the effect of the co‐culture of MM cells with stroma cells, on expression of the MUC1 oncogene, known to confer tumour cells with resistance to apoptosis and necrosis. Co‐culture of stroma with MM cells resulted in increased MUC1 expression by tumour cells. The effect of stromal cell co‐culture on MUC1 expression was not dependent on cell contact and was therefore thought to be due to soluble factors secreted by the stromal cells into the microenvironment. We demonstrated that MUC1 expression was mediated by interleukin‐6 and subsequent up‐regulation of the JAK‐STAT pathway. Interestingly, the effect of stromal cell co‐culture on tumour resistance was partially reversed by silencing of MUC1 in MM cells, consistent with the potential role of MUC1 in mediating resistance to cytotoxic‐based therapies.

DCOne as an Allogeneic Cell-based Vaccine for Multiple Myeloma

Multiple myeloma (MM) is characterized by progressive immune dysregulation, loss of myeloma-specific immunity, and an immunosuppressive milieu that fosters disease growth and immune escape. Accordingly, cancer vaccines that reverse tumor-associated immune suppression represent a promising therapeutic avenue of investigation. We examined the potential of an allogeneic cellular vaccine to generate immune responses against MM tumor cells. The DCOne vaccine is comprised of a human myeloid leukemia cell line differentiated into a fully functional dendritic cell, expressing a range of tumor-associated antigens that are also known targets in MM. We found that the myeloma-specific antigens expressed by the DCOne vaccine can traffic via extracellular vesicles to surrounding antigen-presenting cells, thus stimulating autologous T-cell responses. Indeed, coculture of peripheral blood mononuclear cells from patients with MM with the DCOne vaccine resulted in the expansion of activated CD8+ T cells expressing interferon-&ggr; and perforin, with no significant change in the percentage of CD4+ T cells producing interleukin-10. Further, coculture of patient’s tumor cells with peripheral blood mononuclear cells and DCOne induced cytotoxic T-lymphocyte-mediated killing of autologous MM cells. These findings demonstrate that the allogeneic DCOne vaccine can induce T-cell activation and myeloma-specific immunity via cross presentation of antigens by native antigen-presenting cells.

MUC1‐C drives myeloid leukaemogenesis and resistance to treatment by a survivin‐mediated mechanism

Acute myeloid leukaemia (AML) is an aggressive haematological malignancy with an unmet need for improved therapies. Responses to standard cytotoxic therapy in AML are often transient because of the emergence of chemotherapy‐resistant disease. The MUC1‐C oncoprotein governs critical pathways of tumorigenesis, including self‐renewal and survival, and is aberrantly expressed in AML blasts and leukaemia stem cells (LSCs). However, a role for MUC1‐C in linking leukaemogenesis and resistance to treatment has not been described. In this study, we demonstrate that MUC1‐C overexpression is associated with increased leukaemia initiating capacity in an NSG mouse model. In concert with those results, MUC1‐C silencing in multiple AML cell lines significantly reduced the establishment of AML in vivo. In addition, targeting MUC1‐C with silencing or pharmacologic inhibition with GO‐203 led to a decrease in active β‐catenin levels and, in‐turn, down‐regulation of survivin, a critical mediator of leukaemia cell survival. Targeting MUC1‐C was also associated with increased sensitivity of AML cells to Cytarabine (Ara‐C) treatment by a survivin‐dependent mechanism. Notably, low MUC1 and survivin gene expression were associated with better clinical outcomes in patients with AML. These findings emphasize the importance of MUC1‐C to myeloid leukaemogenesis and resistance to treatment by driving survivin expression. Our findings also highlight the potential translational relevance of combining GO‐203 with Ara‐C for the treatment of patients with AML.

Phase 1 clinical trial evaluating abatacept in patients with steroid-refractory chronic graft-versus-host disease

Steroid-refractory chronic graft-versus-host disease (SR-cGVHD) remains a major cause of morbidity and mortality after allogeneic stem cell transplantation. Innovative immunotherapeutic strategies are urgently needed for the treatment of SR-cGVHD. We conducted a phase 1 clinical trial to evaluate the safety, efficacy, and immune effects of abatacept, a novel immunomodulatory drug that acts as an inhibitor of T-cell activation via costimulatory blockade, in the treatment of SR-cGVHD. The study followed a 3+3 design with 2 escalating abatacept doses: 3 mg/kg and 10 mg/kg, with an expansion cohort treated at 10 mg/kg. Abatacept was well-tolerated with no dose-limiting toxicities. Of the 16 evaluable patients, 44% achieved a clinical partial response per 2005 National Institutes of Health Consensus Criteria. Importantly, abatacept resulted in a 51.3% reduction in prednisone usage in clinical responders (mean baseline, 27 vs 14 mg; P = .01). Increased PD-1 expression on circulating CD4 (P = .009) and CD8 (P = .007) T cells was observed in clinical responders. In summary, abatacept was safe and led to a marked improvement in National Institutes of Health cGVHD scores and a significant reduction in prednisone use. In this cohort of heavily pretreated patients, the results suggest abatacept may be a promising therapeutic agent for SR-cGVHD, and a phase 2 trial has been initiated. This trial was registered at www.clinicaltrials.gov as #NCT01954979.

Decitabine Priming Enhances Mucin 1 Inhibition Mediated Disruption of Redox Homeostasis in Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous neoplasm and patients with relapsed/refractory disease exhibit resistance to standard therapies. We have previously demonstrated that the Mucin 1 C-terminal subunit (MUC1-C) plays a critical role in protection from oxidative stress in CTCL cells. Targeting of MUC1-C with a pharmacologic inhibitor, GO-203, was associated with apoptosis in CTCL. However, disease responses were incomplete underscoring the need for combinatorial strategies that could exploit the vulnerability of CTCL cells to oxidative signals. Cell lines, primary samples, and xenograft models of CTCL were used to assess synergy of GO-203 with decitabine, a hypomethylating agent. Present studies demonstrate that exposure of CTCL cells to decitabine in combination with GO-203, increased the generation of reactive oxygen species (ROS) levels and decreased levels of scavenger molecules, NADP, NADPH, glutathione, and TIGAR, critical to intracellular redox homeostasis. Dual exposure to GO-203 and decitabine resulted in marked downregulation of DNA methyl transferases demonstrating significant synergy of these agents in inducing global and gene specific hypomethylation. Accordingly, treatment with decitabine and GO-203 upregulated the ROS generating enzymes, NADPH oxidase 4 and dual oxidase 2 potentially due to their effect on epigenomic regulation of these proteins. In concert with these findings, exposure to decitabine and GO-203 resulted in heightened apoptotic death in CTCL cell lines, patient-derived primary samples and in a murine xenograft model. These findings indicate that decitabine intensifies MUC1-C inhibition induced redox imbalance and provides a novel combination of targeted and epigenetic agents for patients with CTCL. Mol Cancer Ther; 16(10); 2304–14. ©2017 AACR.