beta-Defensins are small antimicrobial peptides of the innate immune system produced in response to microbial infection of mucosal tissue and skin. We demonstrate that murine beta-defensin 2 (mDF2beta) acts directly on immature dendritic cells as an endogenous ligand for Toll-like receptor 4 (TLR-4), inducing up-regulation of costimulatory molecules and dendritic cell maturation. These events, in turn, trigger robust, type 1 polarized adaptive immune responses in vivo, suggesting that mDF2beta may play an important role in immunosurveillance against pathogens and, possibly, self antigens or tumor antigens.

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Lymphomas express a tumor-specific antigen which can be targeted by cancer vaccination. We evaluated the ability of a new idiotype protein vaccine formulation to eradicate residual t(14;18)+ lymphoma cells in 20 patients in a homogeneous, chemotherapy-induced first clinical complete remission. All 11 patients with detectable translocations in their primary tumors had cells from the malignant clone detectable in their blood by PCR both at diagnosis and after chemotherapy, despite being in complete remission. However, 8 of 11 patients converted to lacking cells in their blood from the malignant clone detectable by PCR after vaccination and sustained their molecular remissions. Tumor-specific cytotoxic CD8+ and CD4+ T cells were uniformly found (19 of 20 patients), whereas antibodies were detected, but apparently were not required for molecular remission. Vaccination was thus associated with clearance of residual tumor cells from blood and long-term disease-free survival. The demonstration of molecular remissions, analysis of cytotoxic T lymphocytes against autologous tumor targets, and addition of granulocyte-monocyte colony-stimulating factor to the vaccine formulation provide principles relevant to the design of future clinical trials of other cancer vaccines administered in a minimal residual disease setting.

Background Endogenous or iatrogenic antitumor immune responses can improve the course of follicular lymphoma (FL), but may be diminished by immune checkpoints in the tumor microenvironment. These may include effects of programmed death (PD)-1, a co-inhibitory receptor that impairs T-cell function and is highly expressed on intratumoral T cells. In a Phase II trial, we determined the activity of pidilizumab, a humanized anti-PD-1 monoclonal antibody, with rituximab in patients with relapsed FL. Methods FL patients with rituximab-sensitive disease relapsing after 1–4 prior therapies were eligible. Pidilizumab was administered at 3 mg/kg every 4 weeks for 4 infusions, plus 8 optional infusions every 4 weeks for patients with stable disease or better. Starting 2 weeks after the first infusion of pidilizumab, rituximab was given at 375 mg/m2 weekly for 4 weeks. The primary endpoint was to assess the overall response rate. Analysis was by intention to treat. Peripheral blood and tumor biopsies were studied to assess immunological effects of pidilizumab. This trial has been completed and was registered at www.clinicaltrials.gov as NCT00904722. Findings The combination was well-tolerated, with no autoimmune or therapy-related grade 3/4 toxicities. The most common grade 1 adverse events were anemia (14 patients) and fatigue (13 patients), and the most common grade 2 adverse event was respiratory infection (5 patients). Overall 19/29 (66%) and complete 15/29 (52%) response rates in 29 evaluable patients were high, with tumor regression in 25/29 (86%) of patients. Median progression-free survival was 18.8 months (95% CI: 14.7 months to not reached). The median response duration for the 19 responders was 20.2 months (95% CI: 13.9 months to not reached). Correlative studies of blood and tumor provided insights into predicting response and understanding mechanisms involved. Interpretation Pidilizumab with rituximab is well-tolerated and its activity compared favorably to historical retreatment with rituximab monotherapy in patients with relapsed FL. Our results establish that immune checkpoint blockade is worthy of further study in FL. Funding National Institutes of Health, Leukemia and Lymphoma Society, Cure Tech Ltd, and UT MD Anderson Cancer Center.

SummaryWe report our experience with 129 cases of double hit lymphoma (DHL), defined as B-cell lymphoma with translocations and/or extra signals involving MYC plus BCL2 and/or BCL6. All cases were reviewed for histopathological classification. Median age was 62 years (range, 18-85), 84% of patients had advanced-stage disease, and 87% had an International Prognostic Index score ≥2. Fourteen patients (11%) had a history of low-grade follicular lymphoma. MYC translocation was present in 81%, and extra signals of MYC in 25% of patients. IGH-BCL2 translocation was present in 84% and extra signals of BCL2 in 12% of patients. Two-year event-free survival (EFS) rates in all patients and patients who received R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), R-EPOCH (rituximab, etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin), and R-HyperCVAD/MA (rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone, alternating with cytarabine plus methotrexate) were 33%, 25%, 67% and 32%, respectively. In patients achieving complete response with initial therapy (n = 71), 2-year EFS rates in patients who did (n = 23) or did not (n = 48) receive frontline stem cell transplantation were 68% and 53%, respectively (P = 0Á155). The cumulative incidence of central nervous system involvement was 13% at 3 years. Multivariate analysis identified performance status ≥2 and bone marrow involvement as independent adverse prognostic factors for EFS and OS. Further research is needed to identify predictive and/or targetable biological markers and novel therapeutic approaches for DHL patients.