Stephen Devereux

CD38 expression in chronic lymphocytic leukemia is regulated by the tumor microenvironment

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease with a highly variable outcome. The prognosis of patients with CLL may be predicted using a number of biomarkers, including the level of CD38 expression at the leukemic cell surface. This study investigates the hypothesis that CD38 expression by CLL cells reflects interactions with nonmalignant cells within pseudofollicles in secondary lymphoid tissue where tumor cell proliferation is thought to occur. CD38 expression is higher in tissues that contain pseudofollicles compared with those that do not. In addition, we show that CD38 expression in CLL is dynamic, changes in response to contact with activated CD4(+) T cells, and identifies cells that are primed to proliferate. Finally, we demonstrate close contact between activated CD4(+) T cells and proliferating tumor in primary patient tissue. Proliferating tumor cells in lymph nodes express CD38, which is in turn associated with an increased number of CD31(+) vascular endothelial cells. Although the factors resulting in colocalization of tumor, T cells, and endothelium remain unclear, the existence of these cellular clusters may provide an explanation for the association between CD38 expression and adverse outcome in CLL and suggests novel therapeutic targets.

Alemtuzumab in Combination With Methylprednisolone Is a Highly Effective Induction Regimen for Patients With Chronic Lymphocytic Leukemia and Deletion of TP53: Final Results of the National Cancer Research Institute CLL206 Trial

PURPOSE In chronic lymphocytic leukemia (CLL), TP53 deletion/mutation is strongly associated with an adverse outcome and resistance to chemotherapy-based treatment. In contrast, TP53 defects are not associated with resistance to the anti-CD52 monoclonal antibody alemtuzumab or methylprednisolone. In an attempt to improve the treatment of TP53-defective CLL, a multicenter phase II study was developed to evaluate alemtuzumab and methylprednisolone in combination. PATIENTS AND METHODS Thirty-nine patients with TP53-deleted CLL (17 untreated and 22 previously treated) received up to 16 weeks of treatment with alemtuzumab 30 mg three times a week and methylprednisolone 1.0 g/m(2) for five consecutive days every 4 weeks. Antimicrobial prophylaxis consisted of cotrimoxazole, itraconazole, and aciclovir (or valganciclovir for asymptomatic cytomegalovirus viremia). The primary end point was response as assigned by an end-point review committee. Secondary end points were safety, progression-free survival (PFS) and overall survival (OS). RESULTS The overall response rate, complete response rate (including with incomplete marrow recovery), median PFS, and median OS were 85%, 36%, 11.8 months, and 23.5 months, respectively, in the entire cohort and 88%, 65%, 18.3 months, and 38.9 months, respectively, in previously untreated patients. Grade 3 to 4 hematologic and glucocorticoid-associated toxicity occurred in 67% and 23% of patients, respectively. Grade 3 to 4 infection occurred in 51% of the overall cohort and in 29% of patients less than 60 years of age. Treatment-related mortality was 5%. CONCLUSION Alemtuzumab plus methypredisolone is the most effective induction regimen hitherto reported in TP53-deleted CLL. The risk of infection is age related and, in younger patients, seems only marginally higher than that associated with rituximab, fludarabine, and cyclophosphamide.

Interaction with Vascular Endothelium Enhances Survival in Primary Chronic Lymphocytic Leukemia Cells via NF-κB Activation and De novo Gene Transcription

Chronic lymphocytic leukemia (CLL) cells rapidly undergo apoptosis in vitro, suggesting that the in vivo microenvironment provides crucial antiapoptotic signals. Overexpression of the antiapoptotic proteins Bcl-2 and Mcl-1 is a hallmark of CLL, and their expression is further enhanced in the lymphoid tissues. However, the high levels of Mcl-1 found in peripheral blood samples, coupled with its short half-life, led us to hypothesize that it must be actively maintained in the peripheral circulation. Coculture of CLL cells with human vascular endothelial cells significantly enhanced tumor cell survival, an effect that was not observed with normal B cells. This was associated with elevated levels of the antiapoptotic proteins Bcl-2, Mcl-1, and Bcl-X(L) and marked increased expression of CD38 and CD49d, both of which are associated with clinically aggressive disease. Because CD38, CD49d, and some Bcl-2 family genes are transcriptional targets for NF-κB, we assessed NF-κB activation following coculture with endothelial cells. DNA binding of the NF-κB subunit Rel A was significantly increased and strongly correlated with changes in transcription of CD38, CD49d, BCL2, MCL1, and BCLXL, effects that were reversed by a peptide inhibitor of Rel A. These effects were not observed following coculture with nonendothelial cell lines. Therefore, CLL cells receive specific survival signals following interaction with endothelial cells mediated through the activation of NF-κB and the induction of downstream target genes. This type of interaction in the peripheral vasculature may explain the constitutive NF-κB activation and the overexpression of Bcl-2 family proteins commonly seen in this disease.

Guidelines for the Management of Mature T-cell and NK-cell Neoplasms (Excluding cutaneous T-cell Lymphoma)

The peripheral T‐cell neoplasms are a biologically and clinically heterogeneous group of rare disorders that result from clonal proliferation of mature post‐thymic lymphocytes. Natural killer (NK) cell neoplasms are included in this group. The World Health Organization classification of haemopoietic malignancies has divided this group of disorders into those with predominantly leukaemic (disseminated), nodal, extra‐nodal or cutaneous presentation. They usually affect adults and are more commonly reported in males than in females. The median age at diagnosis is 61 years with a range of 17–90 years. Although some subtypes may follow a relatively benign protracted course most have an aggressive clinical behaviour and poor prognosis. Excluding anaplastic lymphoma kinase (ALK)‐positive anaplastic large cell lymphoma (ALCL), which has a good outcome, 5‐year survival for other nodal and extranodal T‐cell lymphomas is about 30%. Most patients present with unfavourable international prognostic index scores (>3) and poor performance status. The rarity of these diseases and the lack of randomized trials mean that there is no consensus about optimal therapy for T‐ and NK‐cell neoplasms and recommendations in this guideline are therefore based on small case series, phase II trials and expert opinion.

Evidence for a macromolecular complex in poor prognosis CLL that contains CD38, CD49d, CD44 and MMP-9

Progressive chronic lymphocytic leukaemia is characterized by the accumulation of neoplastic B‐cells in the tissues and correlates with the expression of prognostic biomarkers, such as CD38, CD49d and matrix metalloproteinase‐9 (MMP9), which are involved in migration and tissue invasion. In this study we investigated the physical relationship between these molecules and demonstrated that CD38, CD49d, MMP9 and CD44 were physically associated in a supramolecular cell surface complex. Our findings provide a molecular basis for the correlation between expression of these proteins and prognosis and, as the complex is not present in normal B‐cells, suggest a novel leukaemia‐specific therapeutic target.

Outcomes of alemtuzumab-based reduced intensity conditioning stem cell transplantation using unrelated donors for myelodysplastic syndromes

This prospective study evaluated the outcomes of 75 successive patients receiving a FBC (fludarabine, busulphan, alemtuzumab) reduced‐intensity conditioning (RIC) regimen for myelodysplastic syndromes (MDS) using volunteer unrelated donors(VUD). The prognostic significance of a variety of clinical variables including the recently described haematopoietic cell transplantation co‐morbidity index (HCT‐CI) was assessed. The median age of the cohort was 52·0 years (range: 19–68 years) with a median follow‐up of 1038·5 d. Forty‐nine patients (65%) had an International Prognostic Scoring System stage of ≥Intermediate‐2, 35 (46%) had intermediate or poor risk cytogenetics, and 23 patients(31%) were human leucocyte antigen‐mismatched. The actuarial 3‐year overall survival (OS) and disease‐free survival (DFS) was 43% [95% confidence interval (CI): 37–49] and 41% (95%CI: 35–47) respectively, and the cumulative incidence of extensive chronic graft‐versus‐host disease was 22%. On multivariate analysis, presence of either one class II mismatch or a two‐antigen mismatch adversely influenced transplant‐related mortality, DFS and OS. In addition, disease status at transplantation and the haematopoietic cell transplantation‐specific comorbidity index were independent variables for overall survival. In contrast, both advanced age and pre‐transplant cytogenetic status did not significantly affect overall outcomes. RIC regimens using VUD was associated with durable long‐term survival even in older patients with MDS, and the use of a pre‐transplant comorbidity index may help to improve patient selection for transplantation.

CD49d is an independent prognostic marker that is associated with CXCR4 expression in CLL

The world of chronic lymphocytic leukemia (CLL) research is awash with prognostic markers. However, very few of the current group play a clearly defined role in the pathology of this disease and even fewer represent a tractable therapeutic target. One such marker that fulfils both of these criteria is the integrin CD49d. This molecule been implicated in the capacity of CLL cells to migrate into lymphoid tissues and there is a CD49d blocking antibody, Natalizumab, currently in clinical trials. Here we carried out the largest multi-centre evaluation of CD49d as a prognostic marker in 652 primary CLL samples. We confirm that CD49d is predictive for time to first treatment (P<0.0001) and overall survival (P<0.0001) and increases the prognostic power of CD38, ZAP-70 and IGHV gene mutation status in concordant cases. Furthermore, CD49d retained independent prognostic significance in multivariate analysis. In contrast to previous studies, we showed no correlation between CD49d expression and in vitro resistance to fludarabine in liquid cultures (P=0.28) but CD49d(hi) cells were significantly more resistant than CD49d(lo) cells when assays were carried out on fibronectin-coated plates (P=0.03). Furthermore, we showed for the first time that the expression of CD49d is strongly associated with expression of the chemokine receptor CXCR4 suggesting a co-ordinated role for these molecules in the trafficking of CLL cells to the lymphoid tissues. Taken together, our data support the introduction of CD49d into routine immunophenotyping panels for CLL and indicate that the therapeutic targeting of this molecule may prove useful in this disease.

Outcome of BEAM-autologous and BEAM-alemtuzumab allogeneic transplantation in relapsed advanced stage follicular lymphoma

The role of haematopoietic stem cell transplantation (HSCT) in relapsed follicular lymphoma remains controversial. This study analysed 126 patients with relapsed, advanced stage follicular lymphoma who received BEAM (BCNU [carmustine], cytarabine, etoposide, melphalan)‐alemtuzumab allogeneic HSCT (BEAM‐allo) (n = 44) or BEAM‐autologous HSCT (BEAM‐auto) (n = 82). The BEAM‐allo group had a younger median age (48 years vs. 56 years, P < 0·001) but received a higher median number of therapies pretransplant (P = 0·015) compared with the BEAM‐auto group. There was a higher non‐relapse mortality (NRM) in the BEAM‐allo group compared with the BEAM‐auto group at 1 year (20% vs. 2%, P = 0·001). Older age and heavily pretreated patients were associated with a higher NRM and poorer survival in the BEAM‐allo group. There was, however, a significantly lower relapse rate (20% vs. 43%, P = 0·01) at 3 years with BEAM‐alemtuzumab, with no relapses after 2 years, compared with a continued pattern of relapse in the autologous group. No difference in overall survival (OS) (P = 0·99) or disease‐free survival (DFS) (P = 0·90) was identified at 3 years, whereas a plateau in OS and DFS with crossing of the survival curves in favour of BEAM‐allo group was observed. Furthermore, the ability to re‐induce remissions with donor leucocytes provides additional benefit in favour of allogeneic HSCT.

Impact of pretransplant comorbidities on alemtuzumab-based reduced-intensity conditioning allogeneic hematopoietic SCT for patients with high-risk myelodysplastic syndrome and AML

We report a retrospective analysis of 128 consecutive patients with high-risk myelodysplastic syndrome (MDS) and AML who received an alemtuzumab-based reduced-intensity conditioning hematopoietic SCT (RIC HSCT). The median recipient age was 53 years (range 21–72 years). A total of 49 (38%) recipients had a sibling donor and 79 (62%) had a volunteer-unrelated donor. The hematopoietic cell transplantation-specific comorbidity index (HCT-CI) was assigned to all patients with a score of 0 in 40 (31%), of 1–2 in 45 (35%) and ⩾3 in 43 (34%) patients. The 3-year non-relapse mortality (NRM) was 31%, disease-free survival (DFS) was 41% and overall survival (OS) was 46%. The 3-year NRM for patients with a HCT-CI score of 0, 1–2 or ⩾3 was 16, 24 and 42%, respectively. The 3-year DFS and OS by HCT-CI was 58 and 69% (score 0), 39 and 39% (score 1–2) and 24 and 32% (score ⩾3), respectively. On multivariate analysis, HCT-CI was an independent variable affecting 3-year NRM, DFS and OS (P-value=0.04, 0.01 and <0.01, respectively). Although the disease stage at the time of transplant was an additional independent predictive variable on transplant outcomes, recipient age (>/<50 years) did not have a significant predictive impact. In MDS or AML patients with advanced disease receiving alemtuzumab-based RIC HSCT, the HCT-CI provides an important means of stratifying patients with a high risk of inferior transplant outcomes.

Mimicking the tumour microenvironment: three different co-culture systems induce a similar phenotype but distinct proliferative signals in primary chronic lymphocytic leukaemia cells.

Interactions in the tumour microenvironment can promote chronic lymphocytic leukaemia (CLL) cell survival, proliferation and drug resistance. A detailed comparison of three co‐culture systems designed to mimic the CLL lymph node and vascular microenvironments were performed; two were mouse fibroblast cell lines transfected with human CD40LG or CD31 and the third was a human microvascular endothelial cell line, HMEC‐1. All three co‐culture systems markedly enhanced CLL cell survival and induced a consistent change in CLL cell phenotype, characterized by increased expression of CD38, CD69, CD44 and ITGA4 (CD49d); this phenotype was absent following co‐culture on untransfected mouse fibroblasts. In contrast to HMEC‐1 cells, the CD40LG and CD31‐expressing fibroblasts also induced ZAP70 expression and marked CLL cell proliferation as evidenced by carboxyfluorescein succinimidyl ester labelling and increased Ki‐67 expression. Taken together, our data show that co‐culture on different stroma induced a remarkably similar activation phenotype in CLL cells but only the CD40LG and CD31‐expressing fibroblasts increased ZAP70 expression and CLL cell proliferation, indicating that ZAP70 may play a critical role in this process. This comparative study reveals a number of striking similarities between the co‐culture systems tested but also highlights important differences that should be considered when selecting which system to use for in‐vitro investigations.