Marinus H. J. van Oers

Phase III Trial of Consolidation Therapy With Yttrium-90–Ibritumomab Tiuxetan Compared With No Additional Therapy After First Remission in Advanced Follicular Lymphoma

PURPOSE We conducted an international, randomized, phase III trial to evaluate the efficacy and safety of consolidation with yttrium-90 ((90)Y)-ibritumomab tiuxetan in patients with advanced-stage follicular lymphoma in first remission. PATIENTS AND METHODS Patients with CD20(+) stage III or IV follicular lymphoma, who achieved a complete response (CR)/unconfirmed CR (CRu) or partial response (PR) after first-line induction treatment, were randomly assigned to receive (90)Y-ibritumomab tiuxetan (rituximab 250 mg/m(2) on day -7 and day 0 followed on day 0 by (90)Y-ibritumomab tiuxetan 14.8 MBq/kg; maximum of 1,184 MBq) or no further treatment (control). The primary end point was progression-free survival (PFS), which was calculated from the time of random assignment. RESULTS A total of 414 patients (consolidation, n = 208; control, n = 206) were enrolled at 77 centers. (90)Y-ibritumomab tiuxetan consolidation significantly prolonged median PFS (after a median observation time of 3.5 years) in all patients (36.5 v 13.3 months in control arm; hazard ratio [HR] = 0.465; P < .0001) and regardless of whether patients achieved PR (29.3 v 6.2 months in control arm; HR = 0.304; P < .0001) or CR/CRu (53.9 v 29.5 months in control arm; HR = 0.613; P = .0154) after induction treatment. Median PFS with consolidation was prolonged in all Follicular Lymphoma International Prognostic Index risk subgroups. After (90)Y-ibritumomab tiuxetan consolidation, 77% of patients in PR after induction converted to CR/CRu, resulting in a final CR rate of 87%. The most common toxicity with (90)Y-ibritumomab tiuxetan was hematologic, and grade 3 or 4 infections occurred in 8% of patients. CONCLUSION Consolidation of first remission with (90)Y-ibritumomab tiuxetan in advanced-stage follicular lymphoma is highly effective with no unexpected toxicities, prolonging PFS by 2 years and resulting in high PR-to-CR conversion rates regardless of type of first-line induction treatment.

Rituximab Maintenance Treatment of Relapsed/Resistant Follicular Non-Hodgkin's Lymphoma: Long-Term Outcome of the EORTC 20981 Phase III Randomized Intergroup Study

PURPOSE In 2006, we published the results of the European Organisation for Research and Treatment of Cancer phase III trial EORTC 20981 on the role of rituximab in remission induction and maintenance treatment of relapsed/resistant follicular lymphoma (FL). At that time, the median follow-up for the maintenance phase was 33 months. Now, we report the long-term outcome of maintenance treatment, with a median follow-up of 6 years. PATIENTS AND METHODS Overall, 465 patients were randomly assigned to induction with either six cycles of cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) or rituximab plus CHOP (R-CHOP). Those in complete remission or partial remission after induction (n = 334) were randomly assigned to maintenance treatment with rituximab (375 mg/m(2) intravenously once every 3 months) or observation. RESULTS Rituximab maintenance significantly improved progression-free survival (PFS) compared with observation (median, 3.7 years v 1.3 years; P < .001; hazard ratio [HR], 0.55), both after CHOP induction (P < .001; HR, 0.37) and R-CHOP (P = .003; HR, 0.69). The 5-year overall survival (OS) was 74% in the rituximab maintenance arm, and it was 64% in the observation arm (P = .07). After progression, a rituximab-containing salvage therapy was given to 59% of patients treated with CHOP followed by observation, compared with 26% after R-CHOP followed by rituximab maintenance. Rituximab maintenance was associated with a significant increase in grades 3 to 4 infections: 9.7% v 2.4% (P = .01). CONCLUSION With long-term follow-up, we confirm the superior PFS with rituximab maintenance in relapsed/resistant FL. The improvement of OS did not reach statistical significance, possibly because of the unbalanced use of rituximab in post-protocol salvage treatment.

Constitutive CD27/CD70 Interaction Induces Expansion of Effector-Type T Cells and Results in IFNγ-Mediated B Cell Depletion

The interaction between the TNF receptor family member CD27 and its ligand CD70 provides a costimulatory signal for T cell expansion. Normally, tightly regulated expression of CD70 ensures the transient availability of this costimulatory signal. Mice expressing constitutive CD70 on B cells had higher peripheral T cell numbers that showed increased differentiation toward effector-type T cells. B cell numbers in CD70 transgenic (TG) mice progressively decreased in primary and secondary lymphoid organs. This B cell depletion was caused by CD27-induced production of IFNgamma in T cells. We conclude that apart from its role in controlling the size of the activated T cell pool, CD27 ligation contributes to immunity by facilitating effector T cell differentiation.

miR-34a as part of the resistance network in chronic lymphocytic leukemia

17p (TP53) deletion identifies patients with chronic lymphocytic leukemia (CLL) who are resistant to chemotherapy. The members of the miR-34 family have been discovered to be direct p53 targets and mediate some of the p53-dependent effects. We studied miR-34a and miR-34b/c expression in a large cohort to define their potential role in refractory CLL. While no expression of miR-34b/c could be detected, we found variable expression levels of miR-34a. miR-34a levels were up-regulated after DNA damage in the presence of functional p53, but not in cases with 17p deletion (P < .001). We found a strong correlation of low miR-34a levels with impaired DNA damage response, TP53 mutations (without 17p deletion), and fludarabine-refractory disease (also in the absence of 17p deletion). Up-regulation of miR-34a after irradiation was associated with induction of Bax and p21, but not Puma. CLL cells with reduced miR-34a expression showed increased viability after DNA damage independently of 17p status. Therefore, low expression of miR-34a in CLL is associated with p53 inactivation but also chemotherapy-refractory disease, impaired DNA damage response, and apoptosis resistance irrespective of 17p deletion/TP53 mutation. The elucidation of mechanisms underlying miR-34a regulation and overcoming its role in chemotherapy resistance warrant further study.

Lethal T cell immunodeficiency induced by chronic costimulation via CD27-CD70 interactions

It has been proposed that HIV-1, in addition to directly infecting and killing CD4+ T cells, causes T cell dysfunction and T cell loss by chronic immune activation. We analyzed the effects of chronic immune activation in mice that constitutively expressed CD70, the ligand for the tumor necrosis factor receptor family member CD27, on B cells. CD70 transgenic (CD70 Tg) mice showed a progressive conversion of naive T cells into effector-memory cells, which culminated in the depletion of naive T cells from lymph nodes and spleen. T cell changes depended on continuous CD27-CD70 interactions and T cell antigen receptor stimulation. Despite this hyperactive immune system, CD70 Tg mice died aged 6–8 months from Pneumocystis carinii infection, a hallmark of T cell immunodeficiency. Thus, persistent delivery of costimulatory signals via CD27-CD70 interactions, as may occur during chronic active viral infections, can exhaust the T cell pool and is sufficient to induce lethal immunodeficiency.

Tumor Rejection Induced by CD70-mediated Quantitative and Qualitative Effects on Effector CD8+ T Cell Formation

In vivo priming of antigen-specific CD8+ T cells results in their expansion and differentiation into effector T cells followed by contraction into a memory T cell population that can be maintained for life. Recent evidence suggests that after initial antigenic stimulation, the magnitude and kinetics of the CD8+ T cell response are programmed. However, it is unclear to what extent CD8+ T cell instruction in vivo is modulated by costimulatory signals. Here, we demonstrate that constitutive ligation of the tumor necrosis factor receptor family member CD27 by its ligand CD70 quantitatively augments CD8+ T cell responses to influenza virus infection and EL-4 tumor challenge in vivo by incrementing initial expansion and maintaining higher numbers of antigen-specific T cells in the memory phase. Concomitantly, the quality of antigen-specific T cells improved as evidenced by increased interferon (IFN)-γ production and a greater cytotoxic potential on a per cell basis. As an apparent consequence, the superior effector T cell formation induced by CD70 protected against a lethal dose of poorly immunogenic EL4 tumor cells in a CD8+ T cell– and IFN-γ–dependent manner. Thus, CD70 costimulation enhances both the expansion and per cell activity of antigen-specific CD8+ T cells.

Failing immune control as a result of impaired CD8+ T-cell maturation: CD27 might provide a clue

Despite readily detectable virus-specific CD8(+) T cells in most HIV-infected patients, immune surveillance is eventually lost, leading to progression to AIDS. Recently developed insights into human T-cell differentiation have been used to study the phenotype of virus-specific T cells in HIV-infected individuals. Based on these results, we propose that failing immune control in human viral infection could be a result of impaired cytotoxic T-lymphocyte (CTL) maturation into fully differentiated effector T cells. Impaired maturation is not confined to HIV-specific CD8(+) T cells but could also be involved in failing immunity to Epstein-Barr virus and other viral infections. We postulate that CD27(-) effector CD8(+) T cells might be required for adequate control of chronic viral infection and prevention of disease development.

Myeloablative allogeneic versus autologous stem cell transplantation in adult patients with acute lymphoblastic leukemia in first remission: a prospective sibling donor versus no-donor comparison.

While commonly accepted in poor-risk acute lymphoblastic leukemia (ALL), the role of allogeneic hematopoietic stem cell transplantation (allo-SCT) is still disputed in adult patients with standard-risk ALL. We evaluated outcome of patients with ALL in first complete remission (CR1), according to a sibling donor versus no-donor comparison. Eligible patients (433) were entered in 2 consecutive, prospective studies, of whom 288 (67%) were younger than 55 years, in CR1, and eligible to receive consolidation by either an autologous SCT or an allo-SCT. Allo-SCT was performed in 91 of 96 patients with a compatible sibling donor. Cumulative incidences of relapse at 5 years were, respectively, 24 and 55% for patients with a donor versus those without a donor (hazard ratio [HR], 0.37; 0.23-0.60; P < .001). Nonrelapse mortality estimated 16% (+/- 4) at 5 years after allo-SCT. As a result, disease-free survival (DFS) at 5 years was significantly better in the donor group: 60 versus 42% in the no-donor group (HR: 0.60; 0.41-0.89; P = .01). After risk-group analysis, improved outcome was more pronounced in standard-risk patients with a donor, who experienced an overall survival of 69% at 5 years (P = .05). In conclusion, standard-risk ALL patients with a sibling donor may show favorable survival following SCT, due to both a strong reduction of relapse and a modest nonrelapse mortality. This trial is registered with http://www.trialregister.nl under trial ID NTR228.

Aberrant expression and reverse signalling of CD70 on malignant B cells

In normal lymphoid tissues the tumour necrosis factor‐receptor family member CD27 and its ligand CD70 have a restricted expression pattern. Previously, we reported that expression of CD27 is deregulated in B‐cell leukaemias and lymphomas. Here we show that, although infrequently expressed by normal human B cells in vivo, CD70 is found on 50% of B‐CLLs, 33% of follicle centre lymphomas, 71% of large B‐cell lymphomas, and 25% of mantle cell lymphomas. Interestingly, in the majority of leukaemias and lymphomas examined, CD70 was found to have a capped appearance, a feature that coincided with co‐expression of CD27. Functional analysis showed that a subset of B‐CLLs could proliferate vigorously in response to CD70 mAb but not to CD27 mAb. This response was synergistically enhanced by ligation of CD40 but inhibited by the presence of IL‐4. Additional experiments indicated that the proliferative response was due to an agonistic signal delivered via CD70, rather than blocking of negative signalling by CD27. Thus, next to its role as ligand, in a subset of malignant B cells CD70 can operate as receptor and as such might contribute to progression of these B‐cell malignancies.

B Cells Are Crucial for Both Development and Maintenance of the Splenic Marginal Zone

The splenic marginal zone is a unique compartment that separates the lymphoid white pulp from the surrounding red pulp. Due to the orchestration of specialized macrophages and B cells flanking a marginal sinus, this compartment plays an important role in uptake of blood-borne Ags and it gives the spleen its specialized function in antibacterial immunity. In this study, we demonstrate that both development and maintenance of this marginal zone is highly dependent on the presence of B cells. Spleens from B cell-deficient mice were found to lack both metallophilic and marginal zone macrophages as well as mucosal addressin cellular adhesion molecule-1+ sinus lining cells. Using an inducible Cre/loxP-driven mouse model in which mature B cells could be partially depleted by removal of the B cell receptor subunit Igα, we could show that the integrity and function of an established marginal zone was also dependent on the presence of B cells. This was confirmed in a transgenic model in which all B cells were gradually depleted due to overexpression of the TNF family member CD70. The loss of all cellular subsets from the marginal zone in these CD70 transgenic mice was effectively prevented by crossing these mice on a CD27−/− or TCRα−/− background, because this prohibited the ongoing B cell depletion. Therefore, we conclude that B cells are not only important for the development, but also for maintenance, of the marginal zone. This direct correlation between circulating B cells and the function of the spleen implies an increased risk for B cell lymphopenic patients with bacterial infections.