MicroRNA (miRNA) dysregulation is a hallmark of cutaneous T-cell lymphoma (CTCL), an often-fatal malignancy of skin-homing CD4 T cells for which there are few effective therapies. The role of microRNAs (miRs) in controlling epigenetic modifier-dependent transcriptional regulation in CTCL is unknown. In this study, we characterize a novel miR dysregulation that contributes to overexpression of the epigenetic reader bromodomain-containing protein 4 (BRD4). We used patient CD4 T cells to show diminished levels of miR-29b compared with healthy donor cells. Patient cells and miR-29b mouse cells revealed an inverse relationship between miR-29b and BRD4, the latter of which is overexpressed in these cells. Chromatin immunoprecipitation and sequencing analysis revealed increased genome-wide BRD4 occupancy at promoter and enhancer regions in CD4 T cells from CTCL patients. The cumulative result of BRD4 binding was increased expression of tumor-associated genes such as and, as well as the interleukin-15 (IL-15) receptor complex, the latter enhancing IL-15 autocrine signaling. Furthermore, we confirm the in vivo relevance of this pathway in our IL-15 transgenic mouse model of CTCL by showing that interference with BRD4-mediated pathogenesis, either by restoring miR-29b levels via bortezomib treatment or by directly inhibiting BRD4 binding via JQ1 treatment, prevents progression of CTCL. We describe a novel oncogenic pathway featuring IL-15, miR-29b, and BRD4 in CTCL and suggest targeting of these components as a potentially effective therapy for CTCL patients.
Immunotherapy approaches have advanced rapidly in recent years. While the greatest therapeutic advances so far have been achieved with T cell therapies such as immune checkpoint blockade and CAR-T, recent advances in NK cell therapy have highlighted the therapeutic potential of these cells. Chronic lymphocytic leukemia (CLL), the most prevalent form of leukemia in Western countries, is a very immunosuppressive disease but still shows significant potential as a target of immunotherapy, including NK-based therapies. In addition to their antileukemia potential, NK cells are important immune effectors in the response to infections, which represent a major clinical concern for CLL patients. Here, we review the interactions between NK cells and CLL, describing functional changes and mechanisms of CLL-induced NK suppression, interactions with current therapeutic options, and the potential for therapeutic benefit using NK cell therapies.
Successes with anti-CD20 antibodies in chronic lymphocytic leukemia (CLL) and enhanced activity of Fc-engineered versus unmodified antibody therapy suggest a potentially impactful role for natural killer (NK) cells and other innate immune cells in controlling this disease. Stimulated natural killer cells have shown promise as a cellular therapy but their application has been constrained by limited expansion capacity and low cytotoxic activity against CLL cells. Here, we demonstrate that both healthy donor-derived and CLL patient-derived NK cells expand rapidly when stimulated with feeder cells expressing membrane-bound IL-21 and have potent cytotoxic activity against allogeneic or autologous CLL cells. Combination with anti-CD20 antibodies significantly enhances NK recognition and killing of CLL targets. As any CLL immune therapy would likely be given in combination, we assess commonly-used treatments and demonstrate that ibrutinib has mixed suppressive and protective effects on expanded NK cells whereas expanded NKs are highly resistant to venetoclax. We demonstrate efficacy in vivo in two xenograft mouse models of human CLL that support building upon a regimen of venetoclax and obinutuzumab with mbIL-21-expanded NK cells. Collectively, these data support development of mbIL-21-expanded NKs combined with the CD20 antibody obinutuzumab and venetoclax in the treatment of CLL.
Rare, recurrent balanced translocations occur in a variety of cancers but are often not functionally interrogated. Balanced translocations with the immunoglobulin heavy chain locus (IGH; 14q32) in chronic lymphocytic leukemia (CLL) are infrequent but have led to the discovery of pathogenic genes including CCND1, BCL2, and BCL3. Following identification of a t(X;14)(q28;q32) translocation that placed the mature T cell proliferation 1 gene (MTCP1) adjacent to the immunoglobulin locus in a CLL patient, we hypothesized that this gene may have previously unrecognized importance. Indeed, here we report overexpression of human MTCP1 restricted to the B cell compartment in mice produces a clonal CD5+/CD19+ leukemia recapitulating the major characteristics of human CLL and demonstrates favorable response to therapeutic intervention with ibrutinib. We reinforce the importance of genetic interrogation of rare, recurrent balanced translocations to identify cancer driving genes via the story of MTCP1 as a contributor to CLL pathogenesis.
Chronic lymphocytic leukemia (CLL) transformation to aggressive lymphoma, known as Richter's Transformation (RT), has a dismal prognosis. There are limited data evaluating risk of RT in patients treated with ibrutinib. We performed a retrospective analysis to determine prognostic variables associated with development of RT and overall survival (OS) at progression after treatment with ibrutinib. We identified 559 patients with CLL treated with ibrutinib from 2010–2019. After a median follow‐up of 44.5 months from ibrutinib start, 179 patients progressed and were included in our analysis. After a median follow‐up of 20.8 months from progression, 54 out of 179 patients developed RT. Progression on treatment (hazard ratio [HR] 4.01 [1.60–10.00], p = .003), higher LDH (HR 1.80 for 2‐fold increase [1.33–2.43], p = .0001), and lymphadenopathy without lymphocytosis (HR 2.88 [1.15–7.20], p = .02) were independent prognostic variables for the development of RT at progression. Progression with lymphadenopathy without lymphocytosis continued to be an independent prognostic variable of worse OS post‐progression. In a subset analysis of 50 patients who obtained a PET‐CT at progression, the median SUVmax for patients who would develop RT was 15.2 (n = 30, range: 4.0–46.3) versus those patients who did not develop RT with a SUVmax of 7.7 (n = 20, range: 2.3–27.2) (p = .0030). Median OS from date of RT was 4.0 months, suggesting that prognosis for RT remains poor. A lymph node biopsy to rule out RT should be considered in patients who received ibrutinib who progress on treatment, have an elevated LDH, or progress with lymphadenopathy without lymphocytosis.
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