Optimizing Drug Combinations for T-PLL: Restoring DNA Damage and P53-Mediated Apoptotic Responses.

T-prolymphocytic leukemia (T-PLL) is a mature T-cell neoplasm associated with marked chemotherapy resistance and continued poor clinical outcomes. Current treatments, i.e. the CD52-antibody alemtuzumab, offer transient responses, with relapses being almost inevitable without consolidating allogeneic transplantation. Recent more detailed concepts of T-PLL's pathobiology fostered the identification of actionable vulnerabilities: (i) altered epigenetics, (ii) defective DNA damage responses, (iii) aberrant cell-cycle regulation, and (iv) deregulated pro-survival pathways, including TCR and JAK/STAT signaling. To further develop related pre-clinical therapeutic concepts, we studied inhibitors of (H)DACs, BCL2, CDK, MDM2, and clas-sical cytostatics, utilizing (a) single-agent and combinatorial compound testing in 20 well-characterized and molecularly-profiled primary T-PLL (validated by additional 42 cases), and (b) 2 independent murine models (syngeneic transplants and patient-derived xenografts). Overall, the most efficient/selective single-agents and combinations (in vitro and in mice) in-cluded Cladribine, Romidepsin ((H)DAC), Venetoclax (BCL2), and/or Idasanutlin (MDM2). Cladribine sensitivity correlated with expression of its target RRM2. T-PLL cells revealed low overall apoptotic priming with heterogeneous dependencies on BCL2 proteins. In additional 38 T-cell leukemia/lymphoma lines, TP53 mutations were associated with resistance towards MDM2 inhibitors. P53 of T-PLL cells, predominantly in wild-type configuration, was amenable to MDM2 inhibition, which increased its MDM2-unbound fraction. This facilitated P53 activa-tion and down-stream signals (including enhanced accessibility of target-gene chromatin re-gions), in particular synergy with insults by Cladribine. Our data emphasize the therapeutic potential of pharmacologic strategies to reinstate P53-mediated apoptotic responses. The identified efficacies and their synergies provide an informative background on compound and patient selection for trial designs in T-PLL.

XPO1 blockade with KPT-330 promotes apoptosis in cutaneous T-cell lymphoma by activating the p53-p21 and p27 pathways.

Dysregulated nuclear-cytoplasmic trafficking has been shown to play a role in oncogenesis in several types of solid tumors and hematological malignancies. Exportin 1 (XPO1) is responsible for the nuclear export of several proteins and RNA species, mainly tumor suppressors. KPT-330, a small molecule inhibitor of XPO1, is approved for treating relapsed multiple myeloma and diffuse large B-cell lymphoma. Cutaneous T-cell lymphoma (CTCL) is an extranodal non-Hodgkin lymphoma with an adverse prognosis and limited treatment options in advanced stages. The effect of therapeutically targeting XPO1 with KPT-330 in CTCL has not been established. We report that XPO1 expression is upregulated in CTCL cells. KPT-330 reduces cell proliferation, induces G1 cell cycle arrest and apoptosis. RNA-sequencing was used to explore the underlying mechanisms. Genes associated with the cell cycle and the p53 pathway were significantly enriched with KPT-330 treatment. KPT-330 suppressed XPO1 expression, upregulated p53, p21WAF1/Cip1, and p27Kip1 and their nuclear localization, and downregulated anti-apoptotic protein (Survivin). The in vivo efficacy of KPT-330 was investigated using a bioluminescent xenograft mouse model of CTCL. KPT-330 blocked tumor growth and prolonged survival (p < 0.0002) compared to controls. These findings support investigating the use of KPT-330 and next-generation XPO1 inhibitors in CTCL.

Hepatitis B Virus and B-cell lymphoma: evidence, unmet need, clinical impact, and opportunities.

Nearly a billion people worldwide are infected with the hepatitis B Virus (HBV) and about a third of them have chronic infection. HBV is an important cause of morbidity and mortality, including acute and chronic hepatitis and hepatocellular carcinoma (HCC). Screening and control of primary HBV infection through vaccination represent a major advance in global public health, but large sections of the world population, in both developed and underdeveloped countries, remain unscreened and unvaccinated. In addition to being a global cause of liver disease, an important role of HBV in lymphoma has also emerged. First, the high risk of HBV reactivation in previously infected patients receiving chemo-immunotherapy necessitates the systematic evaluation of HBV serological status in all non-Hodgkin's lymphoma (NHL) cases and preemptive antiviral therapy for those who may have chronic or occult HBV infection. Second, HBV has been shown to infect lymphocytes, namely B-cells, and has been associated with a higher risk of developing B-cell lymphoma, most clearly in countries where HBV is endemic. While the risk of HBV reactivation with chemoimmunotherapy in NHL is well known, the role and the impact of HBV as a global lymphoma risk factor and potential oncogenic driver in B-cells are very poorly understood. Here, we review the clinical and scientific evidence supporting an association between HBV and B-cell lymphoma, with a particular focus on diffuse large B-cell lymphoma (DLBCL) and provide an overview of the estimated impact of HBV infection on the biology and clinical course of DLBCL. We also discuss ways to gain a better insight into the unmet need posed by HBV in lymphoma and whether assessing immune responses to HBV, measuring viral loads, and detecting the presence of HBV-encoded proteins in tumor tissue could be integrated into the molecular and clinical risk stratification of patients with DLBCL.

The role of interleukin-15 in the development and treatment of hematological malignancies.

Cytokines are a vital component of the immune system that controls the activation and growth of blood cells. However, chronic overexpression of cytokines can trigger cellular events leading to malignant transformation. The cytokine interleukin-15 (IL-15) is of particular interest, which has been shown to contribute to the development and progression of various hematological malignancies. This review will provide an overview of the impact of the immunopathogenic function of IL-15 by studying its role in cell survival, proliferation, inflammation, and treatment resistance. We will also review therapeutic approaches for inhibiting IL-15 in blood cancers.

The B-cell receptor in control of tumor B-cell fitness: Biology and clinical relevance.

Surface expression of a functional B cell antigen receptor (BCR) is essential for the survival and proliferation of mature B cells. Most types of B-cell lymphoproliferative disorders retain surface BCR expression, including B-cell non-Hodgkin lymphomas (B-NHL) and chronic lymphocytic leukemia (CLL). Targeting BCR effectors in B-NHL cell lines in vitro has indicated that this signaling axis is crucial for malignant B cell growth. This has led to the development of inhibitors of BCR signaling, which are currently used for the treatment of CLL and several B-NHL subtypes. Recent studies based on conditional BCR inactivation in a MYC-driven mouse B-cell lymphoma model have revisited the role of the BCR in MYC-expressing tumor B cells. Indeed, lymphoma cells losing BCR expression continue to grow unless subjected to competition with their BCR-expressing counterparts, which causes their elimination. Here, we discuss the molecular nature of the fitness signal delivered by the BCR to MYC-expressing malignant B cells, ensuring their preferential persistence within a rapidly expanding tumor population. We also review growing evidence of Ig-negative cases belonging to several B-NHL subtypes and CLL, and discuss the clinical implications of these findings in relation to an emerging picture of clinical resistances to anti-BCR therapies.

Bone Involvement in Hodgkin's Lymphoma: Clinical Features and Outcome.

Hodgkin's lymphoma (HL) is now a highly curable disease, with an improving 5-year survival rate that has now reached 86%. At the time of presentation, HL is usually almost entirely confined to the lymph nodes. We performed a retrospective single-institution study of 384 cases with a median follow-up of 44 months, with the aim of identifying clinical and radiological characteristics and outcomes of patients with bone HL; 32 patients (8%) had primary bone involvement, always with concurrent nodal disease. These included 22 men (69%) and 10 women (31%) with the median age as 41 years. Advanced stages and nodular sclerosis histology prevailed among the subgroup. Radiographic features of bone HL are not specific but indicate a destructive malignant process with osteosclerosis and/or osteolysis. With current chemotherapeutic regimens, the long-term prognosis of patients with osseous HL appears good. The presence of bone lesions in HL should not be interpreted as implying a worse prognosis than without bone involvement.

Extralymphatic Disease Is an Independent Prognostic Factor in Hodgkin Lymphoma.

PURPOSE: To identify the characteristics and outcomes of patients with extralymphatic Hodgkin lymphoma. PATIENTS AND METHODS: We performed a retrospective single-institution study of 341 cases comprising 207 male (61%) and 134 female (39%) subjects with a median follow-up of 44 months. RESULTS: Fifty-five patients (16%) had extralymphatic disease. The sites were lung in 29 patients (44%), bone in 22 (33%), liver in 12 (18%), and kidney in 3 (5%). In 46 patients (86%) only one organ was involved, while in 7 patients (13%) extralymphatic disease was present in 2 sites and in 2 patients (3%) in 3 sites. The extralymphatic disease group had a poorer prognosis than the lymphatic disease group. Complete remission rates in the extralymphatic and lymphatic patient subsets were 65% and 82% (P = .043), respectively. CONCLUSION: Extralymphatic disease in patients with Hodgkin lymphoma is a rare occurrence (16%) associated with poor clinical outcome.