Hmga2 promotes the development of myelofibrosis in Jak2V617F knockin mice by enhancing TGF-ß1 and Cxcl12 pathways.

Myelofibrosis (MF) is a devastating blood disorder. The JAK2V617F mutation has been detected in ∼50% cases of MF. Elevated expression of high-mobility group AT hook 2 (HMGA2) has also been frequently observed in patients with MF. Interestingly, upregulation of HMGA2 expression has been found in association with the JAK2V617F mutation in significant cases of MF. However, the contribution of HMGA2 in the pathogenesis of MF remains elusive. To determine the effects of concurrent expression of HMGA2 and JAK2V617F mutation in hematopoiesis, we transduced bone marrow cells from Jak2V617F knockin mice with lentivirus expressing Hmga2 and performed bone marrow transplantation. Expression of Hmga2 enhanced megakaryopoiesis, increased extramedullary hematopoiesis, and accelerated the development of MF in mice expressing Jak2V617F Mechanistically, the data show that expression of Hmga2 enhances the activation of transforming growth factor-ß1 (TGF-ß1) and Cxcl12 pathways in mice expressing Jak2V617F In addition, expression of Hmga2 causes upregulation of Fzd2, Ifi27l2a, and TGF-ß receptor 2. Forced expression of Cxcl12, Fzd2, or Ifi27l2a increases megakaryocytic differentiation and proliferation in the bone marrow of Jak2V617F mice, whereas TGF-ß1 or Cxcl12 stimulation induces collagen deposition in the bone marrow mesenchymal stromal cells. Together, these findings demonstrate that expression of Hmga2 cooperates with Jak2V617F in the pathogenesis of MF.

Loss of Ezh2 cooperates with Jak2V617F in the development of myelofibrosis in a mouse model of myeloproliferative neoplasm.

An activating JAK2V617F mutation has been found in ∼50% patients with myelofibrosis (MF). Inactivating mutations in histone methyltransferase enhancer of zeste homolog 2 (EZH2) also have been observed in patients with MF. Interestingly, inactivating EZH2 mutations are often associated with JAK2V617F mutation in MF, although their contributions in the pathogenesis of MF remain elusive. To determine the effects of concomitant loss of EZH2 and JAK2V617F mutation in hematopoiesis, we generated Ezh2-deficient Jak2V617F-expressing mice. Whereas expression of Jak2V617F alone induced a polycythemia vera-like disease, concomitant loss of Ezh2 significantly reduced the red blood cell and hematocrit parameters but increased the platelet counts in Jak2V617F knock-in mice. Flow cytometric analysis showed impairment of erythroid differentiation and expansion of megakaryocytic precursors in Ezh2-deficient Jak2V617F mice. Moreover, loss of Ezh2 enhanced the repopulation capacity of Jak2V617F-expressing hematopoietic stem cells. Histopathologic analysis revealed extensive fibrosis in the bone marrow (BM) and spleen of Ezh2-deleted Jak2V617F mice. Transplantation of BM from Ezh2-deleted Jak2V617F mice into wild-type animals resulted in even faster progression to MF. Gene expression profiling and chromatin immunoprecipitation sequence analysis revealed that S100a8, S100a9, Ifi27l2a, and Hmga2 were transcriptionally derepressed, and the H3K27me3 levels in these gene promoters were significantly reduced on Ezh2 deletion in hematopoietic progenitors of Jak2V617F mice. Furthermore, overexpression of S100a8, S100a9, Ifi27l2a, or Hmga2 significantly increased megakaryocytic colonies in the BM of Jak2V617F mice, indicating a role for these Ezh2 target genes in altered megakaryopoiesis involved in MF. Overall, our results suggest that loss of Ezh2 cooperates with Jak2V617F in the development of MF in Jak2V617F-expressing mice.

Crizotinib induces apoptosis and gene expression changes in ALK+ anaplastic large cell lymphoma cell lines; brentuximab synergizes and doxorubicin antagonizes.

BACKGROUND: Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL) shows 60-70% event free survival with standard treatments. Targeted therapies are being tested for increased benefit and/or reduced toxicity, but interactions with standard agents are not well known. METHODS: We exposed four ALCL cell lines to two targeted agents, crizotinib and brentuximab vedotin, and to two standard agents, doxorubicin and vinblastine. For each agent and combination, we measured apoptosis and expression of approximately 300 previously annotated genes of interest using targeted RNA-sequencing. An aurora kinase inhibitor, alisertib, was similarly tested for gene expression effects. RESULTS: Only crizotinib, alone or in combination, showed significant effects (adjusted P < 0.05) on expression and apoptosis. One hundred and nine of 277 gene expressions showed crizotinib-associated differential expression, mostly downregulation, 62 associated with apoptosis, and 28 associated with both crizotinib and apoptosis. Doxorubicin was antagonistic with crizotinib on gene expression and apoptosis. Brentuximab was synergistic with crizotinib in apoptosis, and not antagonistic in gene expression. Vinblastine also appeared synergistic with crizotinib but did not achieve statistical significance. Alisertib did not show significant expression changes. CONCLUSIONS: Our data suggest that crizotinib induces apoptosis through orderly changes in cell signaling associated with ALK inhibition. Expression effects of crizotinib and associated apoptosis are antagonized by doxorubicin, but apoptosis is synergized by brentuximab vedotin and possibly vinblastine. These findings suggest that concurrent use of crizotinib and doxorubicin may be counterproductive, while the pairing of crizotinib with brentuximab (or vinblastine) may increase efficacy. Alisertib did not induce expression changes at cytotoxic dosage.

Variant histology, IgD and CD30 expression in low-risk pediatric nodular lymphocyte predominant Hodgkin lymphoma: A report from the Children's Oncology Group.

BACKGROUND: Histologic prognostic factors have been described for nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). This study examines histologic and immunophenotypic variants in a clinical trial for pediatric NLPHL. PROCEDURE: One hundred sixty-eight cases of localized NLPHL were examined for histologic variants, CD30 and immunoglobulin D (IgD) expression, and outcome. Histologic types were scored categorically as 0 = 0, 1 ≤ 25%, and 2 > 25% of the sample. RESULTS: Fifty-eight (35.1%) cases showed only typical nodular with or without serpiginous histology (types A and B). The remainder showed mixtures of histologies. The numbers of patients with score 2 are 85 (50.6%) type A, 21 (12.5%) type B, 46 (27.4%) with extranodular large B cells (type C), 3 with T-cell-rich nodular pattern (type D), 55 (32.7%) with diffuse T-cell-rich (type E) pattern, and 2 (1.2%) with diffuse B-cell pattern (type F). Higher level of types C (P = 0.048) and D (P = 0.033) resulted in lower event-free survival (EFS). Cytoplasmic IgD was found in 65 of 130 tested (50%), did not significantly associate with EFS but positively correlated with types C and E histology (P < 0.0001) and negatively correlated with types A (P = 0.0003) and B (P = 0.006). Seventeen (10%) expressed CD30, with no adverse effect. CONCLUSIONS: Variant histology is common in pediatric NLPHL, especially types C and E, which are associated with IgD expression. Type C variant histology and possibly type D are associated with decreased EFS, but neither IgD nor CD30 are adverse features. Variant histology may warrant increased surveillance, but did not affect overall survival.

Childhood Hodgkin International Prognostic Score (CHIPS) Predicts event-free survival in Hodgkin Lymphoma: A Report from the Children's Oncology Group.

BACKGROUND: Early response to initial chemotherapy in Hodgkin lymphoma (HL) measured by computed tomography (CT) and/or positron emission tomography (PET) after two to three cycles of chemotherapy may inform therapeutic decisions. Risk stratification at diagnosis could, however, allow earlier and potentially more efficacious treatment modifications. PATIENTS AND METHODS: We developed a predictive model for event-free survival (EFS) in pediatric/adolescent HL using clinical data known at diagnosis from 1103 intermediate-risk HL patients treated on Children's Oncology Group protocol AHOD0031 with doxorubicin, bleomycin, vincristine, etoposide, prednisone, cyclophosphamide (ABVE-PC) chemotherapy and radiation. Independent predictors of EFS were identified and used to develop and validate a prognostic score (Childhood Hodgkin International Prognostic Score [CHIPS]). A training cohort was randomly selected to include approximately half of the overall cohort, with the remainder forming the validation cohort. RESULTS: Stage 4 disease, large mediastinal mass, albumin (<3.5), and fever were independent predictors of EFS that were each assigned one point in the CHIPS.  Four-year EFS was 93.1% for patients with CHIPS = 0, 88.5% for patients with CHIPS = 1, 77.6% for patients with CHIPS = 2, and 69.2% for patients with CHIPS = 3. CONCLUSIONS: CHIPS was highly predictive of EFS, identifying a subset (with CHIPS 2 or 3) that comprises 27% of intermediate-risk patients who have a 4-year EFS of <80% and who may benefit from early therapeutic augmentation.  Furthermore, CHIPS identified higher risk patients who were not identified by early PET or CT response. CHIPS is a robust and inexpensive approach to predicting risk in patients with intermediate-risk HL that may improve ability to tailor therapy to risk factors known at diagnosis.

Critical role of Jak2 in the maintenance and function of adult hematopoietic stem cells.

Jak2, a member of the Janus kinase family of nonreceptor protein tyrosine kinases, is activated in response to a variety of cytokines, and functions in survival and proliferation of cells. An activating JAK2V617F mutation has been found in most patients with myeloproliferative neoplasms, and patients treated with Jak2 inhibitors show significant hematopoietic toxicities. However, the role of Jak2 in adult hematopoietic stem cells (HSCs) has not been clearly elucidated. Using a conditional Jak2 knockout allele, we have found that Jak2 deletion results in rapid loss of HSCs/progenitors leading to bone marrow failure and early lethality in adult mice. Jak2 deficiency causes marked impairment in HSC function, and the mutant HSCs are severely defective in reconstituting hematopoiesis in recipient animals. Jak2 deficiency also causes significant apoptosis and loss of quiescence in HSC-enriched LSK (Lin(-)Sca-1(+)c-Kit(+)) cells. Jak2-deficient LSK cells exhibit elevated reactive oxygen species levels and enhanced p38 MAPK activation. Mutant LSK cells also show defective Stat5, Erk, and Akt activation in response to thrombopoietin and stem cell factor. Gene expression analysis reveals significant downregulation of genes related to HSC quiescence and self-renewal in Jak2-deficient LSK cells. These data suggest that Jak2 plays a critical role in the maintenance and function of adult HSCs.

A highly curable lymphoma occurs preferentially in the proximal tibia of young patients.

The presentation of two 19-year-old male subjects with stage I non-Hodgkin lymphoma in the proximal tibia prompted an extensive review of institutional and national databases to assess whether there is any statistical evidence that these reflected a previously overlooked syndromic pattern of presentation. The institutional records of a single institution were reviewed for presentation of non-Hodgkin lymphoma in the bone. The records of two additional institutions were reviewed for all reports of non-Hodgkin lymphoma in the tibia. Analysis was performed on data from Surveillance, Epidemiology, and End Results (SEER) dichotomized to bone presentation in the lower extremity versus other bones. Institutional databases included 20 patients with tibial presentation of lymphoma with a median age of 22.5 years (versus 42 for all bone lymphomas; P<0.001). Eighteen out of twenty patients had diffuse large B-cell lymphoma, and all patients aged ≤40 achieved remission and apparent cure. Distinctive and unusual features were a tendency for bilateral involvement of the tibia and sclerotic changes on X-ray. SEER data included 808 cases of bone lymphoma; the fraction of cases presenting in the lower extremity versus other bone sites is higher at ages ≤40 years (38% versus 19%; P<0.0001). Presentation in the lower extremity, as compared with other bone sites, confers 97% overall survival in patients aged ≤40 (versus 82%; P=0.01). This survival effect was independent of stage. In contrast, no significant difference in overall survival was identified for lower extremity versus non-lower extremity site for age >40. These data show a previously undescribed syndromic pattern of disease presentation: bone lymphoma in young patients is likely to present in the lower extremity-specifically the proximal tibia-has atypical sclerotic features on X-ray, is often bilateral, and has an excellent prognosis compared with bone lymphomas at other sites matched for stage and age.

Critical requirement for Stat5 in a mouse model of polycythemia vera.

The JAK2V617F mutation has been identified in most cases of Ph-negative myeloproliferative neoplasms (MPNs) including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Expression of JAK2V617F results in constitutive activation of multiple signaling molecules/pathways. However, the key signaling downstream of JAK2V617F required for transformation and induction of MPNs remains elusive. Using a mouse genetic strategy, we show here that Stat5 is absolutely required for the pathogenesis of PV induced by Jak2V617F. Whereas expression of Jak2V617F in mice resulted in all the features of human PV, including an increase in red blood cells, hemoglobin, hematocrit, white blood cells, platelets, and splenomegaly, deletion of Stat5 in the Jak2V617F knockin mice normalized all the blood parameters and the spleen size. Furthermore, deletion of Stat5 completely abrogated erythropoietin (Epo)-independent erythroid colony formation evoked by Jak2V617F, a hallmark feature of PV. Re-expression of Stat5 in Stat5-deficient Jak2V617F knockin mice completely rescued the defects in transformation of hematopoietic progenitors and the PV phenotype. Together, these results indicate a critical function for Stat5 in the pathogenesis of PV. These findings also provide strong support for the development of Stat5 inhibitors as targeted therapies for the treatment of PV and other JAK2V617F-positive MPNs.

Tyrosine 201 is required for constitutive activation of JAK2V617F and efficient induction of myeloproliferative disease in mice.

The JAK2V617F mutation has been detected in most cases of Ph-negative myeloproliferative neoplasms (MPNs). The JAK2V617F protein is a constitutively activated tyrosine kinase that leads to transformation of hematopoietic progenitors. Previous studies have shown that several tyrosine residues within JAK2 are phosphorylated on growth factor or cytokine stimulation. However, the role of these tyrosine residues in signaling and transformation mediated by JAK2V617F remains unclear. In this study, we sought to determine the role of tyrosine 201, which is a potential binding site for Src homology 2 domain-containing proteins, in JAK2V617F-induced hematopoietic transformation by introducing a tyrosine-to-phenylalanine point mutation (Y201F) at this site. We observed that the Y201F mutation significantly inhibited cytokine-independent cell growth and induced apoptosis in Ba/F3-EpoR cells expressing JAK2V617F. The Y201F mutation also resulted in significant inhibition of JAK2V617F-mediated transformation of hematopoietic cells. Biochemical analyzes revealed that the Y201F mutation almost completely inhibited constitutive phosphorylation/activation of JAK2V617F. We also show that the Y201 site of JAK2V617F promotes interaction with Stat5 and Shp2, and constitutive activation of downstream signaling pathways. Furthermore, using a BM transduction/transplantation approach, we found that tyrosine 201 plays an important role in the induction of MPNs mediated by JAK2V617F.

Efficacy of vorinostat in a murine model of polycythemia vera.

The discovery of the JAK2V617F mutation in most patients with Ph-negative myeloproliferative neoplasms has led to the development of JAK2 kinase inhibitors. However, JAK2 inhibitor therapy has shown limited efficacy and dose-limiting hematopoietic toxicities in clinical trials. In the present study, we describe the effects of vorinostat, a small-molecule inhibitor of histone deacetylase, against cells expressing JAK2V617F and in an animal model of polycythemia vera (PV). We found that vorinostat markedly inhibited proliferation and induced apoptosis in cells expressing JAK2V617F. In addition, vorinostat significantly inhibited JAK2V617F-expressing mouse and human PV hematopoietic progenitors. Biochemical analyses revealed significant inhibition of phosphorylation of JAK2, Stat5, Stat3, Akt, and Erk1/2 in vorinostat-treated, JAK2V617F-expressing human erythroleukemia (HEL) cells. Expression of JAK2V617F and several other genes, including GATA1, KLF1, FOG1, SCL, C/EPBα, PU.1, and NF-E2, was significantly down-regulated, whereas the expression of SOCS1 and SOCS3 was up-regulated by vorinostat treatment. More importantly, we observed that vorinostat treatment normalized the peripheral blood counts and markedly reduced splenomegaly in Jak2V617F knock-in mice compared with placebo treatment. Vorinostat treatment also decreased the mutant allele burden in mice. Our results suggest that vorinostat may have therapeutic potential for the treatment of PV and other JAK2V617F-associated myeloproliferative neoplasms.

Conditional expression of heterozygous or homozygous Jak2V617F from its endogenous promoter induces a polycythemia vera-like disease.

A somatic point mutation (V617F) in the JAK2 tyrosine kinase was found in a majority of patients with polycythemia vera (PV), essential thrombocythemia, and primary myelofibrosis. However, contribution of the JAK2V617F mutation in these 3 clinically distinct myeloproliferative neoplasms (MPNs) remained unclear. To investigate the role of JAK2V617F in the pathogenesis of these MPNs, we generated an inducible Jak2V617F knock-in mouse, in which the expression of Jak2V617F is under control of the endogenous Jak2 promoter. Expression of heterozygous mouse Jak2V617F evoked all major features of human polycythemia vera (PV), which included marked increase in hemoglobin and hematocrit, increased red blood cells, leukocytosis, thrombocytosis, splenomegaly, reduced serum erythropoietin (Epo) levels and Epo-independent erythroid colonies. Homozygous Jak2V617F expression also resulted in a PV-like disease associated with significantly greater reticulocytosis, leukocytosis, neutrophilia and thrombocytosis, marked expansion of erythroid progenitors and Epo-independent erythroid colonies, larger spleen size, and accelerated bone marrow fibrosis compared with heterozygous Jak2V617F expression. Biochemical analyses revealed Jak2V617F gene dosage-dependent activation of Stat5, Akt, and Erk signaling pathways. Our conditional Jak2V617F knock-in mice provide an excellent model that can be used to further understand the molecular pathogenesis of MPNs and to identify additional genetic events that cooperate with Jak2V617F in different MPNs.

Erythroid lineage-restricted expression of Jak2V617F is sufficient to induce a myeloproliferative disease in mice.

The JAK2V617F mutation has been found in most cases of Ph-negative myeloproliferative neoplasms. Recent studies have shown that expression of Jak2V617F in the hematopoietic compartment causes marked expansion of erythroid progenitors and their transformation to cytokine-independence. To determine if erythroid progenitors are the target cells for induction and propagation of Jak2V617F-evoked myeloproliferative neoplasm, we used a conditional Jak2V617F knock-in mouse and an erythroid-lineage specific EpoRCre line. Erythroid-specific expression of heterozygous or homozygous Jak2V617F resulted in a polycythemia-like phenotype characterized by increase in hematocrit and hemoglobin, increased red blood cells, erythropoietin-independent erythroid colonies and splenomegaly. Transplantation of Jak2V617F-expressing erythroid progenitors from the diseased mice into secondary recipients could not propagate the disease. Our results suggest that erythroid lineage-restricted expression of Jak2V617F is sufficient to induce a polycythemia-like disease in a gene-dose dependent manner. Jak2V617F mutation, however, does not confer leukemia stem cell-like properties to erythroid progenitors.

ALK+ anaplastic large cell lymphoma exhibits phosphatidylinositol-3 kinase/Akt activity with retained but inactivated PTEN--a report from the Children's Oncology Group.

BACKGROUND: ALK+ anaplastic large cell lymphoma (ALCL) is usually a disease of young patients. We investigated phosphatidylinositol-3 kinase (PI3K)/Akt pathway-associated factors in pediatric cases and cell lines. PROCEDURE: Patient materials consisted of tissue slides of ALK+/CD30+ ALCL from 33 patients treated on Pediatric Oncology Group protocols (9219, n = 8 and 9315, n = 25). Slides were examined by immunohistochemistry for phospho(p)-Akt and PTEN, the primary feedback regulator of the pathway, as well as for p27kip1 and stathmin-1. ALCL cell lines SUDHL-1 and Karpas-299 were examined for ALK, pALK, pAkt, p27/Kip1, PTEN, pPTEN, CD30, pSTAT3, and pSTAT5; ALK inhibition was performed using compound PF-2341066 and PTEN genes were sequenced. RESULTS: A majority of patients expressed pAkt, PTEN, and stathmin, with p27kip1 levels less than controls. Cell lines showed expression of ALK, pALK, pSTAT3, pSTAT5, CD30, pAkt, PTEN, and pPTEN, with p27 slightly less than positive controls, and germline PTEN DNA. There was evidence of phosphorylated PTEN (pPTEN) associated with inhibited function. Pharmacologic inhibition of activated ALK diminished pSTAT3, pSTAT5, and CD30 expression but not pAkt or pPTEN in cultured cell lines. CONCLUSION: We conclude that the PI3K/Akt pathway is activated in many, though not all, pediatric ALK+ ALCL. Our data suggest that activation of this pathway involves post-translational regulation of PTEN. Pharmacologic inhibition of activated ALK does not reduce modest levels of activated Akt as it does with the more abundant levels of activated STAT3 or STAT5. Future therapy of ALCL might, in selected patients, best combine agents inhibiting PI3K/Akt with those targeting ALK.

Response-dependent and reduced treatment in lower risk Hodgkin lymphoma in children and adolescents, results of P9426: a report from the Children's Oncology Group.

BACKGROUND: Hodgkin lymphoma is highly curable but associated with significant late effects. Reduction of total treatment would be anticipated to reduce late effects. This aim of this study was to demonstrate that a reduction in treatment was possible without compromising survival outcomes. METHODS: Protocol P9426, a response-dependent and reduced treatment for low risk Hodgkin lymphoma (stages I, IIA, and IIIA(1) ) was designed in 1994 based on a previous pilot project. Patients were enrolled from October 15, 1996 to September 19, 2000. Patients were randomized to receive or not receive dexrazoxane and received two cycles of chemotherapy consisting of doxorubicin, bleomycin, vincristine, and etoposide. After two cycles, patients were evaluated for response. Those in complete response (CR) received 2,550 cGy of involved field radiation therapy (IFRT). Patient with partial response or stable disease, received two more cycles of chemotherapy and IFRT at 2,550 cGy. RESULTS: There were 294 patients enrolled, with 255 eligible for analysis. The 8-year event free survival (EFS) between the dexrazoxane randomized groups did not differ (EFS 86.8 ± 3.1% with DRZ, and 85.7 ± 3.3% without DRZ (P = 0.70). Forty-five percent of patients demonstrated CR after two cycles of chemotherapy. There was no difference in EFS by histology, rapidity of response, or number of cycles of chemotherapy. Six of the eight secondary malignancies in this study have been previously reported. CONCLUSIONS: Despite reduced therapy and exclusion of most patients with lymphocyte predominant histology, EFS and overall survival are similar to other reported studies. The protocol documents that it is safe and effective to reduce therapy in low-risk Hodgkin lymphoma based on early response to chemotherapy with rapid responding patients having the same outcome as slower-responding patients when given 50% of the chemotherapy.

Genetic ablation of Pim1 or pharmacologic inhibition with TP-3654 ameliorates myelofibrosis in murine models.

Myelofibrosis (MF) is the deadliest form of myeloproliferative neoplasm (MPN). The JAK inhibitor Ruxolitinib can reduce constitutional symptoms but it does not substantially improve bone marrow fibrosis. Pim1 expression is significantly elevated in MPN/MF hematopoietic progenitors. Here, we show that genetic ablation of Pim1 blocked the development of myelofibrosis induced by Jak2V617F and MPLW515L. Pharmacologic inhibition of Pim1 with a second-generation Pim kinase inhibitor TP-3654 significantly reduced leukocytosis and splenomegaly, and attenuated bone marrow fibrosis in Jak2V617F and MPLW515L mouse models of MF. Combined treatment of TP-3654 and Ruxolitinib resulted in greater reduction of spleen size, normalization of blood leukocyte counts and abrogation of bone marrow fibrosis in murine models of MF. TP-3654 treatment also preferentially inhibited Jak2V617F mutant hematopoietic progenitors in mice. Mechanistically, we show that TP-3654 treatment significantly inhibits mTORC1, MYC and TGF-ß signaling in Jak2V617F mutant hematopoietic cells and diminishes the expression of fibrotic markers in the bone marrow. Collectively, our results suggest that Pim1 plays an important role in the pathogenesis of MF, and inhibition of Pim1 with TP-3654 might be useful for treatment of MF.

A risk-adapted, response-based approach using ABVE-PC for children and adolescents with intermediate- and high-risk Hodgkin lymphoma: the results of P9425.

Current treatment strategies for Hodgkin lymphoma result in excellent survival but often confer significant long-term toxicity. We designed ABVE-PC (doxorubicin, bleomycin, vincristine, etoposide, prednisone, cyclophosphamide) to (1) enhance treatment efficacy by dose-dense drug delivery and (2) reduce risk of long-term sequelae by response-based reduction of cumulative chemotherapy. Efficient induction of early response by dose-dense drug delivery supported an early-response-adapted therapeutic paradigm. The 216 eligible patients were younger than 22 years with intermediate- or high-risk Hodgkin lymphoma. ABVE-PC was administered every 21 days. Rapid early responders (RERs) to 3 ABVE-PC cycles received 21 Gy radiation to involved regions; RER was documented in 63% of patients. Slow early responders received 2 additional ABVE-PC cycles before 21 Gy radiation. Five-year event-free-survival was 84%: 86% for the RER and 83% for the slow early responders (P = .85). Only 1% of patients had progressive disease. Five-year overall survival was 95%. With this regimen, cumulative doses of alkylators, anthracyclines, and epipodophyllotoxins are below thresholds usually associated with significant long-term toxicity. ABVE-PC is a dose-dense regimen that provides outstanding event-free survival/overall survival with short duration, early-response-adapted therapy.

Expression of signal transducer and activator of transcription 3 (STAT3) in primary central nervous system diffuse large B-cell lymphoma: a retrospective analysis of 17 cases.

Most primary central nervous system lymphomas (PCNSL) occurring in immunocompetent patients are diffuse large B-cell lymphomas (DLBCL), characterized by poor prognosis. An activated B-cell (ABC) origin of PCNSL has been postulated based on bcl-6 and MUM-1 expression by majority of these tumors. ABC DLBCL has been functionally subdivided using gene expression profiling and immunohistochemical analysis into STAT3-high and STAT-3 low subsets. A potentially crucial difference between STAT3-high and STAT3-low ABC DLBCL is in the expression of bcl-2 family members. STAT3-high cases are generally bcl-2 low and STAT3-low cases show higher expression of bcl-2. Further mechanisms such as activation of nuclear factor-kappa B (NF-κB) activation seem to be responsible for upregulation of bcl-2 in ABC subtype of DLBCL with an adverse outcome. As deregulation of STAT-3 pathway is known to play a critical role in ABC DLBCL and majority of the PCNSL are of the ABC subtype we studied the immunohistochemical expression of STAT-3 proteins in PCNSL along with other traditional markers (CD10, bcl-6, MUM-1 and bcl-2) in 17 cases of PCNSL occurring in immunocompetent patients. Despite lack of STAT3 expression in all our cases, majority (70%) of the patients with bcl-2 positive PCNSL had an adverse outcome similar to that reported in systemic lymphomas of ABC subtype. Based on our observations we propose that PCNSL represents a distinct subset of ABC diffuse large B-cell lymphomas with low STAT3 expression and perhaps mechanisms other than interaction of STAT-3 and NF-κB pathways may play a role in upregulation of bcl-2 in PCNSL. To the best of our knowledge expression of STAT-3 protein in PCNSL which represents a distinct anatomical subset of ABC DLBCL with a dismal prognosis has not been studied before.