[Allogeneic haematopoietic stem cell transplantation - an overview]

Allogeneic haematopoietic stem cell transplantation is an effective treatment option for chemotherapy-refractory or relapsed haematological malignancies such as leukaemias and lymphomas. After conditioning with chemotherapy with or without total body irradiation, donor cells are infused to reconstitute haematopoiesis. Donor-derived immune cells induce immune reactions to control or eradicate the underlying disease, thereby going beyond the effect of chemotherapy. This graft-versus-tumour effect (GvT) is often accompanied by detrimental graft-versus-host reactions (graft-versus-host disease, GvHD), which substantially influence the mortality and morbidity after transplantation. The balance between GvHD and GvT, implementing various parameters such as donor selection, stem cell source, conditioning, immune reconstitution and immunosuppressive regimens, represents the challenge in the field of allogeneic stem cell transplantation.

Characterization of tumor-associated B-cell subsets in patients with colorectal cancer

Purpose:

A precise understanding of the mechanisms by which human immune cell subsets affect tumor biology will be critical for successful treatment of cancer using immunotherapeutic approaches. Recent evidence suggests that B cells can both promote and inhibit the development and progression of tumors. The aim of this study was to characterize the composition of the B-cell infiltrates in colorectal cancers (CRC) in order to gain further insight into the role of B cells in CRC.

Experimental Design:

In this study we characterized B-cell subsets in primary tumors (n=38), metastases (n=6) and blood (n=46) of 51 patients with a diagnosis of CRC and blood of 10 healthy controls. B-cell subsets were analyzed by flow cytometry or immunohistochemistry.

Results:

Peripheral blood of CRC patients contained a higher percentage of memory B cells than that of age-matched healthy controls. Furthermore, the percentage of B cells within tumors was higher than that in the peripheral blood of CRC patients while metastases were typically devoid of tumor-infiltrating B cells. Tumor-associated B cells were enriched for activated and terminally differentiated B cells. Relevant proportions of regulatory B cells could only be detected in advanced cancer and metastases.

Conclusion:

B cells constitute a significant proportion of the immune infiltrate in CRC. The B-cell infiltrate of primary CRC is characterized by an accumulation of terminally differentiated memory B cells or plasma cells suggestive of a specific immune response against the tumor. However advanced tumors and metastases are also infiltrated by a considerable number of regulatory B cells.

Chronic lymphocytic leukemia: 2015 Update on diagnosis, risk stratification, and treatment

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the commonest leukemia in western countries. The disease typically occurs in elderly patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that impair apoptosis of clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen as well as B-cell markers.

PROGNOSIS

Two prognostic staging systems exist, the Rai and Binet staging systems, which are established by physical examination and blood counts. Various biological and genetic markers also have prognostic value. Deletions of the short arm of chromosome 17 (del(17p)) predict resistance to available chemotherapies. Comprehensive prognostic scores are currently being developed.

THERAPY

Patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. For physical fit patients, chemoimmunotherapy with fludarabine, cyclophosphamide, and rituximab remains the current standard therapy. For unfit patients, treatment with an anti-CD20 antibody (obinutuzumab or rituximab or ofatumumab) plus a milder chemotherapy (Chlorambucil) may be applied. At relapse, the initial treatment may be repeated, if the treatment-free interval exceeds two to three years. If the disease relapses earlier, therapy should be changed using alternative agents such as bendamustine (plus rituximab), alemtuzumab, lenalidomide, ofatumumab, ibrutinib, or idelalisib. Patients with a del(17p) or TP53 mutation can be treated with ibrutinib or a combination of idelalisib and rituximab. An allogeneic SCT may be considered in relapsing patients with TP53 mutations or del(17p) or patients that are refractory to repeated chemoimmunotherapies. Future challenges: Several new agents (e.g., ibrutinib, idelalisib, obinutuzumab) hold the potential to improve the outcome of patients with CLL. However, their optimal use (in terms of combination, sequence, and duration) is unknown. Therefore, CLL patients should be treated in clinical trials whenever possible.

Omission of dacarbazine or bleomycin, or both, from the ABVD regimen in treatment of early-stage favourable Hodgkin's lymphoma (GHSG HD13): an open-label, randomised, non-inferiority trial

BACKGROUND

The role of bleomycin and dacarbazine in the ABVD regimen (ie, doxorubicin, bleomycin, vinblastine, and dacarbazine) has been questioned, especially for treatment of early-stage favourable Hodgkin's lymphoma, because of the drugs' toxicity. We aimed to investigate whether omission of either bleomycin or dacarbazine, or both, from ABVD reduced the efficacy of this regimen in treatment of Hodgkin's lymphoma.

METHODS

In this open-label, randomised, multicentre trial (HD13) we compared two cycles of ABVD with two cycles of the reduced-intensity regimen variants ABV (doxorubicin, bleomycin, and vinblastine), AVD (doxorubicin, vinblastine, and dacarbazine), and AV (doxorubicin and vinblastine), in patients with newly diagnosed, histologically proven, classic or nodular, lymphocyte predominant Hodgkin's lymphoma. In each treatment group, 30 Gy involved-field radiotherapy (IFRT) was given after both cycles of chemotherapy were completed. From Jan 28, 2003, patients were centrally randomly assigned (1:1:1:1) with a minimisation method to the four groups. Because of high event rates, assignment to the AV and ABV groups stopped early, on Sept 30, 2005, and Feb 10, 2006; assignment to ABVD and AVD continued (1:1) until Sept 30, 2009. Our primary objective was to show non-inferiority of the experimental variants compared with ABVD in terms of freedom from treatment failure (FFTF), by excluding a difference of 6% after 5 years corresponding to a hazard ratio (HR) of 1.72, via a 95% CI. Analyses reported here include qualified patients only, and between-group comparisons include only patients recruited during the same period. The trial was registered, number ISRCTN63474366.

FINDINGS

Of 1502 qualified patients, 566, 198, 571, and 167 were randomly assigned to receive ABVD, ABV, AVD, or AV, respectively. 5 year FFTF was 93.1%, 81.4%, 89.2%, and 77.1% with ABVD, ABV, AVD, and AV, respectively. Compared with ABVD, inferiority of the dacarbazine-deleted variants was detected with 5 year differences of -11.5% (95% CI -18.3 to -4.7; HR 2.06 [1.21 to 3.52]) for ABV and -15.2% (-23.0 to -7.4; HR 2.57 [1.51 to 4.40]) for AV. Non-inferiority of AVD compared with ABVD could also not be detected (5 year difference -3.9%, -7.7 to -0·1; HR 1.50, 1.00 to 2.26). 178 (33%) of 544 patients given ABVD had WHO grade III or IV toxicity, compared with 53 (28%) of 187 given ABV, 142 (26%) of 539 given AVD, and 40 (26%) of 151 given AV. Leucopenia was the most common event, and highest in the groups given bleomycin.

INTERPRETATION

Dacarbazine cannot be omitted from ABVD without a substantial loss of efficacy. With respect to our predefined non-inferiority margin, bleomycin cannot be safely omitted either, and the standard of care for patients with early-stage favourable Hodgkin's lymphoma should remain ABVD followed by IFRT.

FUNDING

Deutsche Krebshilfe and Swiss State Secretariat for Education and Research.

[Chronic lymphocytic leukemia : treatment concepts in transition]

BACKGROUND

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western hemisphere and mainly affects elderly patients. No curative treatment is currently available for this disease.

TREATMENT

Advanced disease is treated according to the patients' fitness and comorbidity burden as well as according the presence of high risk genetic factors in CLL cells. The detection of del(17p) and/or TP53 gene mutations reflects a very unfavorable prognosis and refractoriness to chemotherapy (very high risk CLL). In physically fit patients without high comorbidity burden and without very high risk prognostic factors, chemoimmunotherapy containing fludarabine, cyclophosphamide, and the CD20 antibody rituximab (FCR) is standard therapy because this regimen has been shown to improve overall survival. In patients with significant comorbidity burden, a less intense chemoimmunotherapy regimen should be administered consisting of the alkylating agent chlorambucil plus CD20 antibody. In very high risk patients, kinase inhibitors blocking the signaling transduction pathway of the B cell receptor have been approved since 2014. The same substances are also approved in relapsed CLL. However, in relapsed CLL repetitive administration of chemoimmunotherapy is still an alternative treatment option, especially if the first remission was longer lasting (> 24 months). Allogeneic hematopoietic stem cell transplantation in very high risk CLL or early relapsed disease has become less important than in the past. In some patients considering the risk of the transplantation versus the risk of failing to respond to the new treatment option, this procedure might still be the treatment of choice in order to achieve long-lasting remissions.

CONCLUSION

In the choice of treatment for patients with CLL, several factors must be considered. Because of the broad spectrum of treatment options, therapy within a clinical study is still the best treatment option.

OCTET-CY: a phase II study to investigate the efficacy of post-transplant cyclophosphamide as sole graft-versus-host prophylaxis after allogeneic peripheral blood stem cell transplantation

OBJECTIVE

Post-transplant cyclophosphamide is increasingly used as graft-versus-host disease (GvHD) prophylaxis in the setting of bone marrow transplantation. No data have been published on the use of single-agent GvHD prophylaxis with post-transplant cyclophosphamide in the setting of peripheral blood stem cell transplantation (PBSCT).

METHODS

In a phase II trial, 11 patients with myeloma or lymphoma underwent conditioning with fludarabine and busulfan followed by T-replete PBSCT and application of 50 mg/kg/d of cyclophosphamide on day+3 and +4 without other concurrent immunosuppression (IS).

RESULTS

Median time to leukocyte, neutrophil, and platelet engraftment was 18, 21, and 18 d. The incidence of grade II-IV and grade III-IV GvHD was 45% and 27%, with a non-relapse mortality (NRM) of 36% at one and 2 yr. After median follow-up of 927 d, overall and relapse-free survival was 64% and 34%. Three patients did not require any further systemic IS until day+100 and thereafter. Analysis of immune reconstitution demonstrated rapid T- and NK-cell recovery. B- and CD3+/CD161+NK/T-cell recovery was superior in patients not receiving additional IS.

CONCLUSION

Post-transplant cyclophosphamide as sole IS in PBSCT is feasible and allows rapid immune recovery. Increased rates of severe acute GvHD explain the observed NRM and may advise a temporary combination partner such as mTor-inhibitors in the PBSCT setting.

Dual targeting of Angiopoetin-2 and VEGF potentiates effective vascular normalisation without inducing empty basement membrane sleeves in xenograft tumours

BACKGROUND

Effective vascular normalisation following vascular endothelial growth factor (VEGF) inhibition is associated with endothelial cell regression leaving empty basement membrane sleeves (BMS). These long-lived BMS permit the rapid regrowth of tumour vasculature upon treatment cessation and promote resistance to VEGF-targeting drugs. Previous attempts at removing BMS have failed. Angiopoietin-2 (Ang2) is a vascular destabilizing factor that antagonises normalisation. We hypothesised that Ang2 inhibition could permit vascular normalisation at significantly reduced doses of VEGF inhibition, avoiding excessive vessel regression and the formation of empty BMS.

METHODS

Mice xenografted with human colorectal cancer cells (LS174T) were treated with low (0.5 mg kg(-1)) or high (5 mg kg(-1)) doses of the VEGF-targeting antibody bevacizumab with or without an Ang2 blocking peptibody L1-10. Tumour growth, BMS formation and normalisation parameters were examined including vessel density, pericyte coverage, adherence junctions, leakiness, perfusion, hypoxia and proliferation.

RESULTS

Dual targeting of VEGF and Ang2 achieved effective normalisation at only one-tenth of the dose required with bevacizumab alone. Pericyte coverage, vascular integrity, adherence junctions and perfusion as prerequisites for improved access of chemotherapy were improved without inducing empty BMS that facilitate rapid vascular regrowth.

CONCLUSIONS

Dual targeting of VEGF and Ang2 can potentiate the effectiveness of VEGF inhibitors and avoid the formation of empty BMS.

Embelin inhibits endothelial mitochondrial respiration and impairs neoangiogenesis during tumor growth and wound healing

In the normal quiescent vasculature, only 0.01% of endothelial cells (ECs) are proliferating. However, this proportion increases dramatically following the angiogenic switch during tumor growth or wound healing. Recent evidence suggests that this angiogenic switch is accompanied by a metabolic switch. Here, we show that proliferating ECs increasingly depend on mitochondrial oxidative phosphorylation (OxPhos) for their increased energy demand. Under growth conditions, ECs consume three times more oxygen than quiescent ECs and work close to their respiratory limit. The increased utilization of the proton motif force leads to a reduced mitochondrial membrane potential in proliferating ECs and sensitizes to mitochondrial uncoupling. The benzoquinone embelin is a weak mitochondrial uncoupler that prevents neoangiogenesis during tumor growth and wound healing by exhausting the low respiratory reserve of proliferating ECs without adversely affecting quiescent ECs. We demonstrate that this can be exploited therapeutically by attenuating tumor growth in syngenic and xenograft mouse models. This novel metabolic targeting approach might be clinically valuable in controlling pathological neoangiogenesis while sparing normal vasculature and complementing cytostatic drugs in cancer treatment.

Poor efficacy and tolerability of R-CHOP in relapsed/refractory chronic lymphocytic leukemia and Richter transformation

This phase II trial evaluated efficacy and tolerability of R-CHOP for up to 8 courses in Richter transformation (RT) and up to 6 courses in CLL plus autoimmune cytopenia (AIC) or high-risk (HR) features. HR was defined as fludarabine-refractoriness or early relapse (<36 months) after fludarabine-based treatment; 26 patients were included as HR, 19 patients had AIC, and 15 patients had RT. In the HR cohort, overall response rate was 54%, progression-free and overall survival were 9 and 21 months. In AIC patients overall response rate was 74%, progression-free and overall-survival were 10 and 41 months, respectively, and median increase in hemoglobin was 3.4 g/L. RT patients responded in 67%, progression-free was 10 and overall survival 21 months. The most common adverse events were hematologic toxicities in 92%. Severe infections occurred in 28%. Treatment was discontinued early in 45% of all patients mainly as a result of toxicity. This trial shows that R-CHOP has no role in treating complicated CLL. R-CHOP is associated with significant toxicities and fairly low efficacy compared with almost every other CLL-regimen. In RT, it might still be used as an induction therapy before allogeneic stem cell transplantation.

Past, present and future role of chlorambucil in the treatment of chronic lymphocytic leukemia

For many decades, chlorambucil was the standard of care for chronic lymphocytic leukemia (CLL), but meanwhile has been replaced by purine analog-based chemoimmunotherapy. Monotherapy with the alkylator only retained significance in the treatment of older patients unfit for standard treatment. After successful phase II studies, recent phase III trials established combinations of chlorambucil with anti-CD20 antibodies such as rituximab, ofatumumab and obinutuzumab as a valuable treatment option for these patients. Today, chlorambucil therefore should be used as a chemotherapy backbone for antibody-based chemoimmunotherapy in this patient population rather than as monotherapy. Starting from the past role of chlorambucil in CLL treatment, we here review the most recent efforts to elaborate chlorambucil-based chemoimmunotherapy in CLL and discuss clinically relevant questions that arise from this approach.

Optimization of rituximab for the treatment of diffuse large B-cell lymphoma (II): extended rituximab exposure time in the SMARTE-R-CHOP-14 trial of the german high-grade non-Hodgkin lymphoma study group

PURPOSE

To study pharmacokinetics, toxicity, and efficacy of prolonged rituximab exposure in elderly patients with diffuse large B-cell lymphoma (DLBCL).

PATIENTS AND METHODS

In the SMARTE-R-CHOP-14 trial, rituximab 375 mg/m(2) was administered, together with six cycles of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone on a 14-day schedule (6×R-CHOP-14), on days -4, 0, 10, 29, 57, 99, 155, and 239. Pharmacokinetics and outcome were to be compared with those of patients who had received 6×R-CHOP-14 in combination with eight 2-week applications of rituximab in the RICOVER-60 (Rituximab With CHOP Over Age 60 Years) trial.

RESULTS

The complete response (CR)/unconfirmed CR rate was 85% in 189 evaluable patients, 90% for 90 good-prognosis patients (International Prognostic Index [IPI], 1 or 2), and 81% for 99 poor-prognosis patients (IPI, 3 to 5); 3-year event-free survival (EFS) was 71%, 75%, and 67%, respectively; and 3-year overall survival (OS) was 84%, 88%, and 80%, respectively, with no differences between men and women. The preplanned historical comparison with 306 RICOVER-60 patients (good prognosis, n = 183; poor prognosis, n = 123) revealed no outcome differences for all and good-prognosis patients; however, the longer exposure time in SMARTE-R-CHOP-14 compared with RICOVER-60 was associated with better 3-year EFS (67% v 54%) and OS (80% v 67%) in poor-prognosis patients.

CONCLUSION

Extended rituximab exposure compared with eight 2-week applications in combination with 6×R-CHOP-14 significantly improved outcome of elderly poor-prognosis patients without increasing toxicity. To our knowledge, results obtained with the SMARTE-R-CHOP-14 rituximab schedule are the best reported for elderly patients with DLBCL to date. In the subgroup of poor-prognosis patients treated with extended rituximab exposure, the outcome seemed superior to that of a similar historical cohort of patients treated with 6×R-CHOP-14 plus 2-week rituximab, with similar toxicity. A randomized comparison of the two schedules is warranted.

Inhibition of protein geranylgeranylation specifically interferes with CD40-dependent B cell activation, resulting in a reduced capacity to induce T cell immunity

Ab-independent effector functions of B cells, such as Ag presentation and cytokine production, have been shown to play an important role in a variety of immune-mediated conditions such as autoimmune diseases, transplant rejection, and graft-versus-host disease. Most current immunosuppressive treatments target T cells, are relatively unspecific, and result in profound immunosuppression that places patients at an increased risk of developing severe infections and cancer. Therapeutic strategies, which interfere with B cell activation, could therefore be a useful addition to the current immunosuppressive armamentarium. Using a transcriptomic approach, we identified upregulation of genes that belong to the mevalonate pathway as a key molecular event following CD40-mediated activation of B cells. Inhibition of 3-hydroxy-3-methylglutaryl CoA reductase, the rate-limiting enzyme of the mevalonate pathway, by lipophilic statins such as simvastatin and atorvastatin resulted in a specific inhibition of B cell activation via CD40 and impaired their ability to act as stimulatory APCs for allospecific T cells. Mechanistically, the inhibitory effect resulted from the inhibition of protein geranylgeranylation subsequent to the depletion of mevalonate, the metabolic precursor for geranylgeranyl. Thus, inhibition of geranylgeranylation either directly through geranylgeranyl transferase inhibitors or indirectly through statins represents a promising therapeutic approach for the treatment of diseases in which Ag presentation by B cells plays a role.