Many DNA-hypermethylated cancer genes are occupied by the Polycomb (PcG) repressor complex in embryonic stem cells (ESCs). Their prevalence in the full spectrum of cancers, the exact context of chromatin involved, and their status in adult cell renewal systems are unknown. Using a genome-wide analysis, we demonstrate that ∼75% of hypermethylated genes are marked by PcG in the context of bivalent chromatin in both ESCs and adult stem/progenitor cells. A large number of these genes are key developmental regulators, and a subset, which we call the “DNA hypermethylation module,” comprises a portion of the PcG target genes that are down-regulated in cancer. Genes with bivalent chromatin have a low, poised gene transcription state that has been shown to maintain stemness and self-renewal in normal stem cells. However, when DNA-hypermethylated in tumors, we find that these genes are further repressed. We also show that the methylation status of these genes can cluster important subtypes of colon and breast cancers. By evaluating the subsets of genes that are methylated in different cancers with consideration of their chromatin status in ESCs, we provide evidence that DNA hypermethylation preferentially targets the subset of PcG genes that are developmental regulators, and this may contribute to the stem-like state of cancer. Additionally, the capacity for global methylation profiling to cluster tumors by phenotype may have important implications for further refining tumor behavior patterns that may ultimately aid therapeutic interventions.

CD19 is a pan B-cell surface receptor expressed from pro-B-cell development until its down-regulation during terminal differentiation into plasma cells. CD19 represents an attractive immunotherapy target for cancers of lymphoid origin due to its high expression levels on the vast majority of non-Hodgkin's lymphomas and some leukemias. A humanized anti-CD19 antibody with an engineered Fc domain (XmAb5574) was generated to increase binding to Fc; receptors on immune cells and thus increase Fc-mediated effector functions. In vitro, XmAb5574 enhanced antibodydependent cell-mediated cytotoxicity 100-fold to 1,000-fold relative to an anti-CD19 IgG1 analogue against a broad range of B-lymphoma and leukemia cell lines. Furthermore, XmAb5574 conferred antibody-dependent cell-mediated cytotoxicity against patient-derived acute lymphoblastic leukemia and mantle cell lymphoma cells, whereas the IgG1 analogue was inactive. XmAb5574 also increased antibody-dependent cellular phagocytosis and apoptosis. In vivo, XmAb5574 significantly inhibited lymphoma growth in prophylactic and established mouse xenograft models, and showed more potent antitumor activity than its IgG1 analogue. Comparisons with a variant incapable of Fc; receptor binding showed that engagement of these receptors is critical for optimal antitumor efficacy. These results suggest that XmAb5574 exhibits potent tumor cytotoxicity via direct and indirect effector functions and thus warrants clinical evaluation as an immunotherapeutic for CD19 + hematologic malignancies.

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High-dose therapy (HDT) for non-Hodgkins lymphoma (NHL) and multiple myeloma (MM) is considered a feasible option for patients aged 60 years. This study compared the outcomes for all patients aged 60 years treated with HDT at the center to a matched cohort group aged <60 years. Results for patients who were 60 years at HDT between 1997--2002 were retrospectively analysed to assess efficacy and safety. Event-free (EFS) and overall survival (OS) rates were compared with a cohort group, matched by disease type, chemotherapy sensitivity, year of treatment and conditioning regimen. Patients with NHL were also matched by International Prognostic Index score. Forty patients aged 60 years were identified. Median age was 65 (range 60--76) with 22 MM and 18 NHL; 50% had 1 or more co-morbidity; 35% had cardiovascular co-morbidity vs. 18% of controls (p=0.075). Response rates (RR) following HDT for MM were: 4 (18%) complete responses (CR) and 18 (82%) partial responses (PR), giving an overall response rate (ORR) of 100%, vs. 77% for controls (p=0.02). For NHL patients there were: 8 CR (44%) and 4 PR (22%), giving an ORR of 67%, vs. 83% for controls (p=0.3). Transplant-related mortality was 8% compared to 5% in controls (p=0.6). Toxicities were similar with the exception of cardiac toxicity, which was significantly higher in patients aged 60 years vs. controls (50% grade 3 vs. 10%: p<0.0001). Atrial fibrillation was the most frequent cardiovascular toxicity (9 patients). At a median follow-up of 33 months, there is no significant difference between older vs. younger patients in median EFS (24 vs. 38 months: p=0.78) or OS (40 months vs. not reached: p=0.23). HDT is feasible and effective in selected patients 60 years with MM and NHL. Patients 60 years are more susceptible to cardiovascular toxicities, particularly atrial fibrillation, but have similar or better response rates following HDT and similar long-term outcomes to younger patients.