Unmutated immunoglobulin variable heavy-chain gene status remains an adverse prognostic factor after autologous stem cell transplantation for chronic lymphocytic leukemia

[Minimal residual disease in chronic lymphocytic leukemia: A still current issue in 2018]

Minimal residual disease (MRD) is widely used in oncohematology. In chronic lymphocytic leukemia (CLL), it can be measured by flow cytometry or polymerase chain reaction and is getting a greater place, owing to the dramatic therapeutic advances in the management this disease. As MRD decrease after chemoimmunotherapy is associated with improved progression free and overall survivals, its measure is now recommended as a surrogate marker for cytotoxic drugs licensures. This association is independent from treatment received and raises a few questions, such as sequential MRD measures to stop treatment in case of an early deep response and on the opposite, treatment continuation until reaching undetectable MRD (with the possible use of maintenance therapy). Furthermore, following MRD after a cytotoxic treatment could lead clinical trials investigators to propose pre-emptive treatments in case of MRD re-growth, to avoid overt relaspe. MRD re-growth kinetics and CD4 count after treatment completion can improve MRD-based survival predictions. On the other hand, BCR inhibitors do not lead to undetectable MRD, but their association with chemoimmunotherapy increases the proportion of patients reaching that goal. Moreover, BCL2 inhibitors do lead to deep response including in the relapse/refractory setting, giving to MRD a central place in currently investigated treatments evaluation.

Evaluation of Interleukin-9 Expression as a Potential Therapeutic Target in Chronic Lymphocytic Leukemia in a Cohort of Egyptian Patients

Chronic lymphocytic leukemia (CLL) is a common lymphoid malignancy that has a highly variable clinical course. Genomic features as zeta-chain-associated protein kinase 70 (ZAP70) expression and CD38 expression provide further differentiation of disease prognosis. Extensive studies have confirmed the oncogenic activities of IL-9 in lymphoma. The aim of the current study was to investigate the contribution of IL-9 expression to the pathogenesis of CLL and its correlation to other prognostic parameters. This study was conducted on 80 patients at diagnosis with CLL and 80 healthy controls. Using real time polymerase chain reaction and enzyme linked immunosorbant assay, IL-9 mRNA expression and its serum level were compared between patients and controls. They were both correlated with other prognostic factors.

RESULTS

There was an overexpression of IL-9 in CLL patients that correlated with modified Rai staging, ZAP70, CD38 and all hallmarks of an active and aggressive disease. The correlation between IL-9 upregulation and patient characteristics provided direct clinical evidence for its contribution to the pathogenesis of CLL. In conclusion, significantly higher expression of IL-9 measured at both the mRNA and the protein levels in patients with CLL that correlates with more complex course of the disease and worse prognosis may allow one to speculate its importance in the pathogenesis of the disease and its possible impact on prognosis.

Immunotherapies in CLL

Chronic lymphocytic leukemia (CLL) is the most frequently diagnosed leukemia in the Western world, yet remains essentially incurable. Although initial chemotherapy response rates are high, patients invariably relapse and subsequently develop resistance to chemotherapy. For the moment, allogeneic hematopoietic stem cell transplant (allo-HSCT) remains the only potentially curative treatment for patients with CLL, but it is associated with high rates of treatment-related mortality. Immune-based treatment strategies to augment the cytotoxic potential of T cells offer exciting new treatment options for patients with CLL, and provide a unique and powerful spectrum of tools distinct from traditional chemotherapy. Among the most novel and promising of these approaches are chimeric antigen receptor (CAR)-based cell therapies that combine advances in genetic engineering and adoptive immunotherapy.

Complex karyotype predicts for inferior outcomes following reduced-intensity conditioning allogeneic transplant for chronic lymphocytic leukaemia

Complex karyotype (CK) on metaphase cytogenetics discriminates poor outcome in chronic lymphocytic leukaemia (CLL) patients undergoing salvage treatment; we hypothesized that it might provide prognostic information for patients undergoing allogeneic stem cell transplant. Fifty-one CLL patients were analysed following transplant; 18-month overall survival (OS), event-free survival (EFS) and cumulative incidence of progression estimates were 35%, 14% and 63%, respectively, in patients with CK (n = 19) versus 83%, 68% and 29% in patients without (n = 32) (P ≤ 0·0001, P ≤ 0·0001, and P = 0·02). In patients with high-risk interphase cytogenetics, CK remained predictive of worse OS (P = 0·02) and EFS (P = 0·009). These findings support further evaluation of metaphase karyotype in transplant risk assessment.

Early autologous stem cell transplantation for chronic lymphocytic leukemia: long-term follow-up of the German CLL Study Group CLL3 trial

The CLL3 trial was designed to study intensive treatment including autologous stem cell transplantation (autoSCT) as part of first-line therapy in patients with chronic lymphocytic leukemia (CLL). Here, we present the long-term outcome of the trial with particular focus on the impact of genomic risk factors, and we provide a retrospective comparison with patients from the fludarabine-cyclophosphamide-rituximab (FCR) arm of the German CLL Study Group (GCLLSG) CLL8 trial. After a median observation time of 8.7 years (0.3-12.3 years), median progression-free survival (PFS), time to retreatment, and overall survival (OS) of 169 evaluable patients, including 38 patients who did not proceed to autoSCT, was 5.7, 7.3, and 11.3 years, respectively. PFS and OS were significantly reduced in the presence of 17p- and of an unfavorable immunoglobulin heavy variable chain mutational status, but not of 11q-. Five-year nonrelapse mortality was 6.5%. When 110 CLL3 patients were compared with 126 matched patients from the FCR arm of the CLL8 trial, 4-year time to retreatment (75% vs 77%) and OS (86% vs 90%) was similar despite a significant benefit for autoSCT in terms of PFS. In summary, early treatment intensification including autoSCT can provide very effective disease control in poor-risk CLL, although its clinical benefit in the FCR era remains uncertain. The trial has been registered with www.clinicaltrials.gov as NCT00275015.

Autologous stem cell transplantation as a first-line treatment strategy for chronic lymphocytic leukemia: a multicenter, randomized, controlled trial from the SFGM-TC and GFLLC

Long-term responses have been reported after autologous stem cell transplantation (ASCT) for chronic lymphocytic leukemia (CLL). We conducted a prospective, randomized trial of ASCT in previously untreated CLL patients. We enrolled 241 patients < 66 years of age with Binet stage B or C CLL. They received 3 courses of mini-CHOP (cyclophosphamide, hydroxydaunorubicin, oncovin, and prednisone/prednisolone) and then 3 courses of fludarabine. Patients in complete response (CR) were then randomized to ASCT or observation, whereas the other patients were randomized to dexamethasone, high-dose aracytin, cisplatin (DHAP) salvage followed by either ASCT or 3 courses of fludarabine plus cyclophosphamide (FC). The primary end point was event-free survival (EFS). After up-front treatment, 105 patients entered CR and were randomized between ASCT (n = 52) and observation (n = 53); their respective 3-year EFS rates were 79.8% and 35.5%; the adjusted hazard ratio was 0.3 (95% CI: 0.1-0.7; P = .003). Ninety-four patients who did not enter CR were randomized between ASCT (n = 46) and FC (n = 48); their respective 3-year EFS rates were 48.9% and 44.4%, respectively; the adjusted hazard ratio was 1.7 (95% CI: 0.9-3.2; P = .13). No difference in overall survival was found between the 2 response subgroups. In young CLL patients in CR, ASCT consolidation markedly delayed disease progression. No difference was observed between ASCT and FC in patients requiring DHAP salvage.

Autologous hematopoietic stem cell transplantation in chronic lymphocytic leukemia: results of European intergroup randomized trial comparing autografting versus observation

We present results of a phase 3 randomized trial of autografting in chronic lymphocytic leukemia versus observation for responding patients after first- or second-line treatment. The primary objective was to demonstrate that autografting improves the 5-year event-free survival (EFS) from 30% to 50%. There were 223 enrolled patients, 72% men and 28% women, 83% after first and 17% after second-line treatment. Binet stages were progressive A 13%, B 67%, C 20%; at randomization, 59% were in complete remission, and 41% in less than complete remission. Patients were randomized between autografting (n = 112) and observation (n = 111). Median EFS was 24.4 months (range, 16.7-32 months) in the observation group and 51.2 months (39.8-62.5 months) in the autografting group; the 5-year EFS was 24% and 42%, respectively (P < .001). Accordingly, the 5-year relapse incidence was 76% versus 54% (P < .001). Median time to relapse requiring therapy or death was 40 months (25-56 months) in the observation arm and 65 months (59-71 months) after autografting (P = .002). Cox modeling confirmed that autografting significantly improved EFS (hazard ratio 0.44, 95% confidence interval 0.30-0.65; P < .001). At 5 years, the probability of OS was 85.5% and 84.3% for autografting and observation, respectively (P = .77). In chronic lymphocytic leukemia, consolidating autografting reduces the risk of progression by more than 50% but has no effect on overall survival.

Stem cell transplantation in chronic lymphocytic leukaemia - steering a safe course over shifting sands

There is no clear consensus regarding the optimal management of chronic lymphocytic leukaemia. Many patients are diagnosed at an advanced age and will die with chronic lymphocytic leukaemia, but of other unrelated causes. A significant minority are diagnosed at an earlier age, or with more aggressive disease, and despite chemotherapy, are likely to die of chronic lymphocytic leukaemia. The infusion of autologous or allogeneic haemopoietic stem cells, following a variety of conditioning regimes, offers the possibility of longer remissions or even cure. We explore the key questions facing clinicians in this field: Who is it best to transplant? When is it best to transplant? How is it best to transplant?

Transplantation in chronic lymphocytic leukemia: timing and expectations

Stem cell transplantation in chronic lymphocytic leukemia (CLL) is an evolving field. Younger patients with high-risk disease might derive the greatest benefit from this approach and the availability of reduced-intensity conditioning regimens has made allogeneic stem cell transplantation more relevant to patients with CLL. Patient selection, timing of transplantation, and method of conditioning, stem cell delivery and immunosuppression appear to influence outcomes. We collect and review the available data to assist clinical decision-making in this field.

High-risk fludarabine-pretreated B-cell chronic lymphocytic leukemia's high response rate following sequential DHAP and alemtuzumab administration though in absence of molecular remission

B-CLL patients with resistant/relapsed disease or adverse prognostic factors at presentation are suitable for alternative treatments. In the present pilot study we investigated a novel intensive chemo-immunotherapy approach for high-risk, fludarabine pretreated patients. Ten patients with resistant/relapsed, advanced stage BCLL were included. Age was 37-60 yr (median 53). All but one had an unmutated IgVH status. The treatment schedule included debulking with two DHAP courses followed by alemtuzumab (30 mg, eight doses), followed by peripheral blood progenitor cell (PBPC) mobilization with intermediate/high-dose cyclophosphamide and by autografting after high-dose mitoxantrone+L-Pam. The DHAP-alemtuzumab combination was highly effective. Eight patients out of 10 responded to DHAP, with a single complete remission. Following alemtuzumab, the number of overall responses increased to nine, and the complete remissions to five. After alemtuzumab PB double-positive clonal CD5+/CD19+ lymphocytes dropped, with median purification rate 99.95%. Owing to poor PBPC mobilization, only five patients underwent autografting, and three of these experienced post-graft recurrence. The six patients entering complete remission were free of disease 3-23 mo after study entry, and three of them were still in remission at 3, 7, and 22 mo. However, molecular evaluation regularly revealed persistence of minimal residual disease, both in all PBPC collections tested and in post-treatment follow-up samples. The use of DHAP/alemtuzumab appears useful to re-induce disease remission in relapsed/refractory, high-risk B-CLL patients. However, the addition of autograft was not usually feasible and of questionable clinical use. Other strategies should thus be considered for remission maintenance.

Ribosome-associated nucleophosmin 1: increased expression and shuttling activity distinguishes prognostic subtypes in chronic lymphocytic leukaemia

Two distinct groups of chronic lymphocytic leukaemia (CLL) are distinguished by the presence or absence of somatic hypermutation of the immunoglobulin heavy-chain gene. CLL without somatic hypermutation has an adverse outcome, but the precise biological differences that underlie this more aggressive clinical-course are unclear. Using a proteomic approach, we found that the two prognostic forms of CLL were consistently distinguished according to their protein expression pattern. The most important difference observed related to the different expression of nucleophosmin 1 between the two forms of CLL. This different expression was not related to apoptosis, proliferation or gene mutation. However, co-immunoprecipitation experiments identified an association between nucleophosmin 1 and ribosomal proteins. Using immunocytofluorescence, nucleophosmin 1 expression was identified in the nucleoli and nucleoplasm of all cells, but in a proportion of cells, nucleophosmin had been transferred from the nucleoplasm to the cytoplasm. Both the fluorescent intensity, and the frequency of cytoplasmic nucleophosmin 1 expression, was higher in CLL without somatic hypermutation. We propose therefore, that nucleophosmin 1, in association with ribosomal proteins, undergoes nucleo-cytoplasmic shuttling in CLL. This process is most prominent in un-mutated CLL and may signify altered protein biosynthesis.

Incorporating prognostic information into treatment decisions in chronic lymphocytic leukemia

Most patients with chronic lymphocytic leukemia are diagnosed at an early stage, when traditional staging systems fail to distinguish those with an aggressive disease course from those with an excellent prognosis. This failure underscores the need for better prognostic markers. Although many markers have been explored, this review focuses on the newer and most clinically relevant markers: cytogenetic aberrations, zeta-associated protein 70, immunoglobulin mutational status, and CD38 expression. Although these markers have been shown to predict outcomes for groups of patients, individual patients may have a variable course; therefore, the outcome for any one patient remains hard to predict. To date, no study has shown a benefit from early cytotoxic therapy for any subgroup of patients with chronic lymphocytic leukemia.

Standardized MRD flow and ASO IGH RQ-PCR for MRD quantification in CLL patients after rituximab-containing immunochemotherapy: a comparative analysis

Rituximab-containing regimens are becoming a therapeutic standard in chronic lymphocytic leukemia (CLL), so that a validation of flow cytometric minimal residual disease (MRD) quantification (MRD flow) in the presence of this antibody is necessary. We therefore compared results obtained by real-time quantitative (RQ)-PCR to MRD flow in 530 samples from 69 patients randomized to receive chemotherapy or chemotherapy plus rituximab. Quantitative MRD levels assessed by both techniques were closely correlated irrespective of therapy (r=0.95). The sensitivity and specificity of MRD flow was not influenced by the presence of rituximab. With 58.9% positive and 26.4% negative samples by both techniques, 85.3% of assessments (452/530) were qualitatively concordant between MRD flow and RQ-PCR. Discordant samples were typically negative by MRD flow and simultaneously positive close to the detection limit of the PCR assays, indicating a higher sensitivity of PCR for very low MRD levels. However, 93.8% of all samples were concordantly classified by both methods using a threshold of 10(-4) to determine MRD positivity. MRD flow and PCR are equally effective for MRD quantification in rituximab-treated CLL patients within a sensitivity range of up to 10(-4), whereas PCR is more sensitive for detecting MRD below that level.

The prognostic evaluation of CLLU1 expression levels in 50 Chinese patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by the relentless accumulation of monoclonal B cells with the appearance of small mature lymphocytes and a characteristic CD5 and CD19 co-expression immunophenotype. The incidence of CLL is lower in Asian countries than in Western countries, where CLL is the most common leukemia. To investigate CLLU1 expression in CLL and explore the relationship between CLLU1 expression and alternative prognostic markers, we measured CLLU1 expression levels by semiquantitative RT-PCR in a cohort of 50 Chinese patients with CLL. Analyses of IgVH somatic mutational status, ZAP-70 expression, CD38 expression, and chromosomal aberrations were also performed. The expression of CLLU1 mRNA was determined in 26 of the 50 cases (52%), among which 7 at Binet A (7/21, 33.33%) and 19 at Binet B + C (19/29, 65.52%). The expression levels of CLLU1 were significantly increased in B + C CLL patients at Binet stage compared with those at Binet stage A (P = 0.005). Data for the IgVH somatic mutational status were available for 20 patients with known CLLU1 expression. Five (25%) patients, all expressed CLLU1 mRNA, displayed unmutated IgVH gene usage. While in 15 patients (15/20, 75%) with mutated IgVH gene, only 6 were CLLU1 positive. Patients with unmutated IgVH genes expressed higher levels of CLLU1 than did those with IgVH mutations (P < 0.05). Among 24 CD38(+)-CLL cases, 17 (70.83%) were CLLU1 positive, whereas only 9 (34.62%) positive cases were identified in 26 CD38(-)-CLL patients. Thus, the expression of CLLU1 in CD38(+)-CLL was significantly higher than that in CD38(-)-CLL. However, no significant difference of CLLU1 expression was found between ZAP-70(+) (14/22, 63.64%) and ZAP-70(-) (12/28, 42.86%) patients (P > 0.05). We conclude that CLLU1 expression was significantly associated with clinical stages, IgVH somatic mutational status and CD38 expression, and might be an important prognostic factor in CLL patients.

ZAP-70 immunoreactivity is a prognostic marker of diseaseprogression in chronic lymphocytic leukemia

The expression of zeta-associated protein 70 (ZAP-70) in chronic lymphocytic leukemia (CLL) seems to correlate with the mutational status of the immunoglobulin heavy-chain variable-region genes, clinical course and patient prognosis. The aim was to determine the prognostic significance of the immunohistochemical expression of ZAP-70 protein in CLL by means of the long-term follow-up of 108 patients. This study identified 3 patterns of ZAP-70 immunoreactivity: negative (58 patients, 54%), weakly positive (20 patients, 18%) and strongly positive (30 patients, 28%). Overall, ZAP-70 immunoreactivity correlated with an abnormal karyotype ( p = 0.017), a lymphocyte doubling time (LDT) of <6 months ( p = 0.001) and <12 months ( p = 0.01), Rai II - IV and Binet B - C stage ( p = 0.013), the clinical need for chemotherapy ( p < 0.001) and the need for more than 1 chemotherapy line ( p < 0.001). Kaplan-Meier analysis demonstrated that ZAP-70 immunoreactivity closely correlated with a shorter LDT ( p < 0.0001) and time from diagnosis to initial therapy ( p = 0.0001). The same significance was retained when the patients were stratified into the ZAP-70 immunoreactivity groups ( p < 0.0001). This study shows that ZAP-70 immunoreactivity can be a reliable prognostic marker in CLL and proposes a system for evaluating the results. The observations support the inclusion of the immunohistochemical expression of ZAP-70 in clinical trials involving CLL patients.

The role of stem cell transplantation in the management of chronic lymphocytic leukaemia

The majority of patients diagnosed with chronic lymphocytic leukaemia (CLL) will ultimately die of their disease. Stem cell transplantation (SCT) remains the only treatment modality capable of cure, but has traditionally been associated with very high morbidity and mortality. We review the results of myeloablative autologous and allogeneic SCT in CLL, discuss the evolution of the new non-myeloablative approaches, and make recommendations for when SCT should be considered in patients with CLL.

Long-term outcome of allogeneic stem cell transplantation in chronic lymphocytic leukemia: analysis after a minimum follow-up of 5 years

In order to evaluate the long-term results of allogeneic stem cell transplantation (ASCT) in B-cell chronic lymphocytic leukemia (CLL), we reviewed the outcome of 12 consecutive CLL patients, who underwent ASCT at the Mayo Clinic prior to July, 2004. Median age was 44 years (range 18-55) and median time from diagnosis to transplant 58.5 months. All patients had failed prior fludarabine-based chemotherapy and all but two patients had chemo-resistant refractory disease at time of transplant. A 'myeloablative' conditioning regimen was used in 11 patients and 'reduced intensity' in one. Bone marrow was the source of hematopoietic stem cells in 10 patients and peripheral blood in two. Donors were matched sibling in nine patients, unrelated in two and partial phenotypic match father in one. Grade II-IV acute and chronic graft versus host disease was documented in five and four patients, respectively. To date, six patients (50%) have died including four early deaths from infection. Complete remission (CR) was documented in eight patients (66.7%) post-transplant; six are currently alive whereas one died at 7 months from infection while still in CR and one relapsed 7 months post-transplant and died later. One CR patient relapsed after 4.5 years but was successfully re-transplanted and remains in second CR for 6.5+ years. Another patient recently relapsed after 10.5 years of CR. Duration of ASCT-induced CR in the remaining four patients was 6.5+, 8.5+, 9+ and 10+ years. All surviving patients displayed excellent performance status without ongoing chronic graft versus host disease. We conclude that ASCT is an effective salvage therapy for fludarabine-refractory CLL but late relapses can occur.

Human leukocyte antigen class II allele association to disease progression in Iranian patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most frequent type of leukemia in Western countries, but its incidence is low in Asian populations. In the present study we determined the frequency of DRB1 and DQB1 alleles in 87 Iranian CLL patients and 100 healthy controls using a polymerase chain reaction (PCR) technique. An increased frequency of DRB1*07 (p = 0.04), DQB1*06 (p = 0.01) alleles, and DRB1*13/DQB1*03 haplotype (p = 0.01) and decreased frequency of the DQB1*03 (p = 0.01) allele were observed in our patients compared with healthy controls. Comparison between patients with indolent (n = 42) and progressive (n = 38) disease revealed a significant increase in DRB1*04 and DRB5 alleles in progressive patients. Similarly, a higher frequency of DRB5 (p = 0.01) allele was observed in CD38(+) compared with CD38(-) patients. Classification of the patients into immunoglobulin variable region heavy-chain genes mutated and unmutated subtypes did not reveal significant differences for the expression of any of the HLA alleles or haplotypes between these two subtypes. Our findings observed in an Iranian population indicate that CLL could be associated with distinct HLA class II alleles and haplotypes of which the DQB1*06 allele and DRB1*13/DQB1*03 haplotype have not already been reported in CLL patients from other ethnic backgrounds. Some HLA class II alleles may contribute to disease progression in CLL.

Interleukin-1B (IL1B) and interleukin-6 (IL6) gene polymorphisms are associated with risk of chronic lymphocytic leukaemia

Common polymorphisms in genes encoding for cytokines implicated in the inflammatory response and Th1/Th2 balance might play a role in the development and prognosis of chronic lymphocytic leukaemia (CLL). To test the hypothesis, we investigated 13 single nucleotide polymorphisms (SNPs) in nine of such genes in a population-based case-control study, conducted in the Italian region of Sardinia in 1999-2003. Forty incident CLL cases and 113 population controls were available for study. The following SNPs were selected: IL1A-889C > T, IL1RN 9589A > T, IL1B-31C > T, IL1B-511C > T, IL2-384T > G, IL6-174G > C, IL6-597G > A, IL10-1082A > G, IL10-3575T > A, TNF-308G > A, LTA- 91A > C, LTA 252A > G and CARD15 nt1007. After adjusting by age and gender, individuals homozygous for the IL1B-511T allele run a lower risk of CLL (OR = 0.1, 95% CI 0.0, 0.8, p = 0.032), while risk showed a 4.5-fold increase associated with the genotype homozygous for the IL6-174C allele (OR = 4.5; 95% CI 1.1, 19.3, p = 0.041). Individuals homozygous for the IL6-174C allele and carrying the homozygous IL1B-511C allele showed an 11-fold increase in CLL risk (OR = 11.4, 95% CI 1.9, 69.4, p = 0.008). None of the other interleukin SNPs evaluated showed any association with CLL risk. Large multicentre pooled studies are warranted, achieving the statistical power required to confirm whether IL6 and IL1B gene polymorphisms might play a role in CLL development and prognosis, as well as the null associations herein reported.

Oral fludarabine and cyclophosphamide as front-line chemotherapy in patients with chronic lymphocytic leukemia. The impact of biological parameters in the response duration

We tested the efficacy and safety of oral fludarabine and cyclophosphamide as front-line therapy in chronic lymphocytic leukemia (CLL) and assessed the influence of immunoglobulin variable region heavy chain (IgVH) gene mutation status, interphase cytogenetic abnormalities, and expression of ZAP-70 and CD38 on clinical outcome. Thirty-seven patients with previously untreated CLL received oral fludarabine (30 mg m(2)) and oral cyclophosphamide (250 mg m(2)) for three consecutive days every 4 weeks for six cycles. Eighteen patients had unmutated and 15 had mutated IgVH genes. Nine patients had the 'high risk' cytogenetic abnormality del(11q22.3) or del(17p13.1). Fifteen patients were ZAP-70-positive and eight patients were CD38-positive. Among the 35 valuable patients, 14 patients (40%) obtained a complete response and 13 (37%) a partial response. The median progression-free survival (PFS) was 23 months and median time to re-treatment (TTR) was 38 months. A significantly lower overall response rate (43% vs. 85%, p = 0.011), a shorter PFS (22 vs. 27 months, p = 0.015), and a shorter TTR (22 vs. 40 months, p = 0.031) were noticed in the 'high risk' cytogenetic abnormalities group; TTR was also shorter in IgVH-unmutated than in IgVH-mutated patients (26 vs. 41 months, p = 0.035). Hematologic toxicity included grade IV neutropenia (ten patients) and grade III/IV anemia (three patients). Gastrointestinal toxicity was mild and no patient required hospitalization. The oral combination of fludarabine and cyclophosphamide is an effective, safe, and well-tolerated regimen that, if confirmed with larger series, will be appropriate especially in patients with low risk biological parameters.

Humoral immune responses against the immature laminin receptor protein show prognostic significance in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. The role of an autologous tumor-specific immune control contributing to the variable length of survival in CLL is poorly understood. We investigated whether humoral immunity specific for the CLL-associated Ag oncofetal Ag/immature laminin receptor (OFA/iLR) has a prognostic value in CLL. Among sera of 67 untreated patients with CLL, 23 (34.3%) had detectable OFA/iLR Abs that were reactive for at least one specific OFA/iLR epitope. Patients with humoral responses compared with patients with nonreactive sera had a longer progression-free survival (p = 0.029). IgG subclass analyses showed a predominant IgG1 and IgG3 response. OFA/iLR Abs were capable of recognizing and selectively killing OFA/iLR-expressing CLL cells in complement-mediated and Ab-dependent cellular cytotoxicity assays. In the analysis of 11 CLL patients after allogeneic hematopoietic stem cell transplantation, 8 showed high values for OFA/iLR Abs that specifically recognized the extracellular domain of the protein, suggesting a potential role of anti-OFA/iLR-directed immune responses to the graft-vs-leukemia effect in CLL. Our data suggest that spontaneous tumor-specific humoral immune responses against OFA/iLR exist in a significant proportion of CLL patients and that superior progression-free survival in those patients could reflect autologous immune control.

Quantitative MRD monitoring identifies distinct GVL response patterns after allogeneic stem cell transplantation for chronic lymphocytic leukemia: results from the GCLLSG CLL3X trial

The purpose of this study was to prospectively analyze minimal residual disease(MRD) kinetics after reduced-intensity allogeneic stem cell transplantation (allo-SCT) in high-risk chronic lymphocytic leukemia (CLL). Subjects were the first 30 consecutive patients from a prospective clinical trial, and seven pilot patients treated identically. Using real-time quantitative-PCR (RQ-PCR) and/or flow-based MRD monitoring (sensitivity >or=10(-4)), five distinct patterns of MRD kinetics could be identified: patients who promptly achieved durable MRD negativity without direct evidence of graft-versus-leukemia (GVL) effects (Group 1) (n=4; no clinical relapse); patients with complete and sustained MRD response after GVL induced by immunosuppression tapering (Group 2) or donor lymphocyte infusions (Group 3) (n=18; one relapse); patients without MRD response due to lack of GVL (Group 4) (n=2; two relapses); patients with incomplete and transient MRD response to GVL (Group 5) (n=4; three relapses). In summary, this study provides a comprehensive map of possible MRD courses and their prognostic implications after T-replete allo-SCT in high-risk CLL, indicating that effective GVL activity is induced virtually in all patients who develop chronic GVHD. However, in a significant proportion of cases, this does not translate into sustained disease control due to development of secondary GVL resistance.

Stem cell transplantation in poor-risk chronic lymphocytic leukemia: assessment of post-transplant minimal residual disease using four- and six-color flow cytometry and allele-specific RQ-PCR

A total of 178 bone marrow samples were taken for minimal residual disease (MRD) analysis after 34 stem cell transplantations for poor-risk chronic lymphocytic leukemia, and 86 of them were analyzed in parallel by flow cytometry and allele-specific oligonucleotide-PCR (ASO-PCR). ASO primer was successfully designed for all patients whose frozen diagnosis samples were available. Flow cytometry and ASO-PCR were concordant, i.e. both either positive or both negative, in 78% of the analyses. Flow cytometry did not detect MRD in any of the samples that were PCR-negative cases. In contrast, ASO-PCR detected MRD in samples that were negative for MRD by flow cytometry in 22% of the analyses. In one patient, the immunophenotype but not the IgV(H) gene sequence had changed during a course of the disease, and MRD could not be followed by flow cytometry. In the remaining cases, the discrepancy was due to a higher sensitivity of ASO-PCR. Autologous stem cell transplantation resulted in clinical complete response in 87% (20/23) of the patients. By flow cytometry, 35% (8/23) of autotransplanted patients became MRD-negative, but only 12.5% (2/16) PCR-negative (sensitivity of ASO-PCR <0.001 and <0.01, respectively). All allotransplanted patients achieved or maintained hematological CR, and five out of nine patients (56%) became PCR-negative (sensitivity of PCR between <0.001 and <0.003), two of them having non-myeloablative conditioning. None of the patients who became PCR-negative after allogeneic transplantation have relapsed.

Chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia is the commonest form of leukaemia in Europe and North America, and mainly, though not exclusively, affects older individuals. It has a very variable course, with survival ranging from months to decades. Major progress has been made in identification of molecular and cellular markers that could predict disease progression in patients with chronic lymphocytic leukaemia. In particular, the mutational profile of immunoglobulin genes and some cytogenetic abnormalities are important predictors of prognosis. However, these advances have raised new questions about the biology, prognosis, and management of chronic lymphocytic leukaemia, some of which are addressed here. In particular, we discuss how better understanding of the function of the B-cell receptor, the nature of genetic lesions, and the balance between proliferation and apoptosis have affected our ability to assess prognosis and to manage chronic lymphocytic leukaemia. Available treatments generally induce remission, although nearly all patients relapse, and chronic lymphocytic leukaemia remains an incurable disease. Advances in molecular biology have enhanced our understanding of the pathophysiology of the disease and, together with development of new therapeutic agents, have made management of chronic lymphocytic leukaemia more rational and more effective than previously. Unfortunately, we know of no way that chronic lymphocytic leukaemia can be prevented. Early detection is practised widely, but seemingly makes no difference to the patient's eventual outcome.

Distinctive IgVH gene segments usage and mutation status in Chinese patients with chronic lymphocytic leukemia

BACKGROUND AND OBJECTIVES

The incidence of chronic lymphocytic leukemia (CLL) in Asian countries is lower than that in the Western ones, where CLL is the most common leukemia. It is a clinically heterogeneous disease, with survival ranging from a few months to decades. The mutation status of the immunoglobulin variable heavy chain (IgVH) gene has significantly improved prediction of the risk for disease progression. We investigated the frequency and mutation status of IgVH gene expression in Chinese patients with CLL.

METHODS

IgVH gene segments usage and mutation status were investigated by multiplex RT-PCR, and the relationship between IgVH somatic mutation status and the expression of CD38 and ZAP-70 was analyzed in 65 CLL patients.

RESULTS

Forty-five (69.2%) patients had mutated IgVH, and 20 (30.8%) had unmutated IgVH. The most frequently expressed VH gene family was found to be VH3 (47.7%) followed by VH4 (40%), VH1 (6.2%), VH2 (4.6%) and VH7 (1.5%), with no expression of VH5 or VH6 gene families. VH1-69 and VH3-21 which commonly overused in Western CLL were very low in our cohort. IgVH gene mutation status was significantly associated with the expression of CD38.

CONCLUSIONS

The frequency of IgVH gene families indicates significant difference in Chinese CLL patients compared with Western patients, suggesting involvement of ethnic and/or environmental factors in CLL disease initiation. The expression of them may be simple and reliable surrogates for the identification of IgVH mutations.

Hematopoietic stem cell transplantation for chronic lymphocytic leukemia: potential cure for an incurable disease

Hematopoietic stem cell transplantation (HSCT) has been used as a treatment modality in patients with chronic lymphocytic leukemia (CLL). Allogeneic HSCT is the only therapy at present that has curative potential in patients with CLL. Allogeneic HSCT using standard myeloablative regimens has been generally associated with high treatment mortality rates and autologous HSCT with high relapse rates. Over the last decade the use of reduced intensity conditioning (non-myeloablative) regimens have reduced the treatment-related mortality after allogeneic-HSCT without affecting the graft-versus-leukemia effectiveness. In addition, the development of molecular and biologic markers has identified high-risk CLL patients that may benefit from earlier treatment with HSCT. This review summarizes the use of existing prognostic markers in CLL and their use in HSCT, and the advances, indications and clinical outcomes of both autologous HSCT and allogeneic HSCT.

Emerging therapy for chronic lymphocytic leukaemia

The presentation, clinical course and prognosis for chronic lymphocytic leukaemia (CLL) is diverse and strategies for therapy reflect this variability. Staging of the disease has assisted in deciding treatment options and more recently the cytogenetic, molecular and surrogate markers of the immunoglobulin heavy chain mutational status, CD38 and ZAP-70, have assisted in further risk stratification. Chemotherapy has been the mainstay of interventional therapy when required and the two most important classes of agents in the treatment of CLL are nucleoside analogues and alkylating agents. Combining these two groups of agents has significantly improved prognosis in this disease. More recently a number of novel agents have been applied to patients with CLL to determine if they represent better therapy. However, allogeneic stem cell transplantation offers perhaps the only realistic chance of a cure in this disease. Clinical trials are still needed to determine the timing and role of this promising treatment modality in the treatment of CLL and, where possible, combined with the emerging awareness of the disease biology, related biological markers and prognostic indicators.

Pathology of chronic lymphocytic leukemia: an update

Chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) is a clonal lymphoproliferative disorder characterized by proliferation of morphologically and immunophenotypically mature lymphocytes. CLL/SLL may proceed through different phases: an early phase in which tumor cells are predominantly small in size, with a low proliferation rate and prolonged cell survival, and a transformation phase with the frequent occurrence of extramedullary proliferation and an increase in large, immature cells. Although some patients with CLL have an indolent disease course and die after many years of unrelated causes, others have very rapidly disease progression and die of the disease within a few years of the diagnosis. In the past few years, considerable progress has been made in our ability to diagnose and classify CLL accurately. Through cytogenetics and molecular biology, it has been shown that CLL and variants are associated with a unique genotypic profile and that these genetic lesions often have a direct bearing on the pathogenesis and prognosis of the disease. Similarly, the development of antibodies to new biologic markers has allowed the identification of a unique immunophenotypic profile for CLL and variants. Moreover, accumulating evidence suggests that CLL cells respond to selected microenvironmental signals and that this confers a growth advantage and an extended survival to CLL cells. In this article, we will review the progress in the pathobiology of CLL and give an update on prognostic markers and tools in current pathology practice for risk stratification of CLL.

Systematic review of high dose chemotherapy and autologous haematopoietic stem cell transplantation for chronic lymphocytic leukaemia: what is the published evidence?

Despite improved responses, chronic lymphocytic leukaemia (CLL) remains incurable with conventional chemotherapy. Patients with poor-risk factors or who fail conventional chemoimmunotherapy are offered autografts, preferably after achieving remission. This report presents the totality of evidence through a systematic review that assessed the efficacy of autografts in CLL. A search of MEDLINE databases from 1966-2006 and hand-search of references identified 82 prospective-randomized, non-randomized comparisons or single-arm trials, of which only nine met our inclusion criteria: two trials were funded by public/government, one by private foundations, one jointly by private/public, and was unclear in five. No randomized controlled trials comparing autografts versus conventional chemotherapy (or chemoimmunotherapy) were found. Six studies were single-arm and three were non-randomized with a control-arm (autologous versus allogeneic). Overall, 361 patients were enrolled, but only 292 were transplanted. Transplant-related mortality ranged from 0% to 9%. Complete responses ranged from 74% to 100% and molecular responses ranged from 57% to 88%. Overall survival ranged from 68% at 3 years to 58% at 6 years. It is uncertain whether autograft is superior to conventional therapy. The high incidence of myelodysplastic syndrome (9-12%) is particularly concerning in CLL, where median survival is 9 years.

Recent progress in the management of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a clonal disease characterized by proliferation and accumulation of small CD5-positive B cells. More than 50% of patients are asymptomatic at diagnosis and usually require no treatment. However, treatment is needed in the advanced and progressive disease. Chlorambucil with or without steroids has been the drug of choice for many years in previously untreated patients with CLL. The purine nucleoside analogs (PNAs), fludarabine (FA), cladribine (2-CdA-chlorodeoxyadenosine) and pentostatin (DCF, 2'-deoxycoformycin) also have been introduced for treatment of CLL. Significantly higher overall response (OR) and complete response (CR) and longer progression free survival (PFS) in patients with CLL treated with FA or 2-CdA have been confirmed in randomized, multicenter trials and more recently in meta-analysis. However, the median survival time did not differ between patients treated with PNA and alkylating agents. Combination therapies with PNAs and cyclophosphamide and especially with cyclophosphamide and rituximab are more active than monotherapy in terms of OR, CR and PFS. Several reports have shown significant activity of alemtuzumab in previously untreated and pretreated patients even when refractory to FA. Alemtuzumab also can be used in CLL as a preparative regimen before stem cell transplantation (SCT) and to eliminate minimal residual disease (MRD). Recently, several new agents have shown promise in treating CLL, including new monoclonal antibodies, agents targeting bcl-2 family of proteins, antisense oligonucleotides and other agents. Moreover, autologous and allogenic hematopoietic cell transplantations are increasingly considered for treatment of patients with CLL. In this review current therapeutic strategies in CLL are presented.

Genetics and risk-stratified approach to therapy in chronic lymphocytic leukemia

The clinical staging systems developed by Rai and Binet have remained the mainstay for clinical decision-making in patients with chronic lymphocytic leukemia (CLL). However, there is substantial heterogeneity in the course of the disease. In recent years molecular and cellular markers have helped to predict the prognosis of patients with CLL. Ig V(H) status and genomic aberrations subdivide CLL into distinct clinical subgroups. Fluorescence in-situ hybridization (FISH) can identify genomic aberrations in approximately 80% of CLL cases. The most frequent aberrations are deletions in 13q, 11q, or 17p, and trisomy 12. Apart from providing insights into the pathogenesis, genomic aberrations identify subgroups of patients with distinct clinical pictures: lymphadenopathy (11q-) or resistance to therapy (17p-). Deletions at 11q and particularly 17p are associated with rapid disease progression or inferior survival. Patients with these genetic abnormalities may be candidates for clinical trials investigating alternative treatments and stem-cell transplantation.

Stem-cell transplantation in chronic lympocytic leukaemia

Excellent response rates are now achieved with modern chemoimmunotherapeutic approaches in chronic lymphocytic leukaemia (CLL), but the disease remains incurable. Younger patients and those with adverse prognostic factors will die from their disease, and are therefore candidates for clinical trials investigating the potential role of haematopoietic stem-cell transplantation (SCT) in the management of their disease. Autologous SCT is feasible and safe, but there is a high incidence of subsequent relapse. Myeloablative allogeneic SCT is associated with high treatment-related morbidity and mortality but few late relapses. Attempts to exploit the graft-versus-leukaemia effect of allogeneic donor cells but to reduce the toxicity are being explored in studies of reduced-intensity conditioning allogeneic SCT in CLL. With many potential treatments available, appropriate patient selection and the timing of SCT in the management of CLL remain controversial and the focus of ongoing clinical trials.

The role of stem-cell transplantation in chronic lympocytic leukemia risk-adapted therapy

Because of the lack of a curative treatment for chronic lymphocytic leukemia (CLL) and the poor prognosis of patients refractory to the newer and more effective therapies for this disease, stem-cell transplantation (SCT) is being increasingly performed in patients with CLL. The available evidence indicates that autologous SCT may prolong survival in highly selected patients, but does not result in cure. Conversely, allogeneic SCT may cure a proportion of patients, including those who are refractory to purine-analog-based therapy or with other unfavorable risk parameters, but at the cost of high morbidity and mortality. Reduced-intensity conditioning (non-myeloablative) regimens may contribute to reducing toxic deaths while preserving the antileukemic effect of the allograft, and results are encouraging in patients with chemosensitive disease. Ongoing randomized studies will hopefully contribute to clarification of the role of SCT in the management of CLL. Meanwhile, SCT in patients with CLL should be performed only within clinical studies.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.

Cellular immune therapy for chronic lymphocytic leukemia

Although chemotherapy can induce complete responses in patients with chronic lymphocytic leukemia (CLL), it is not considered curative. Treated patients generally develop recurrent disease requiring additional therapy, which can cause worsening immune dysfunction, myelosuppression, and selection for chemotherapy-resistant leukemia-cell subclones. Cellular immune therapy promises to mitigate these complications and potentially provide for curative treatment. Most experience with this is in the use of allogeneic hematopoietic stem-cell transplantation (allo-HSCT), in which graft-versus-leukemia (GVL) effects can be observed and shown responsible for long-term disease-free survival. However, use of allo-HSCT for CLL is limited because of the lack of suitable donors and the treatment-related morbidity/mortality for elderly patients, who constitute the majority at risk for developing this disease. The GVL effect, however, suggests there are specific CLL-associated antigens that could be targeted in autologous cellular immune therapy. Effective strategies for this will have to overcome the disease-related acquired immune deficiency and the capacity of the leukemia-cell to induce T-cell tolerance, thereby compromising the activity of even conventional vaccines in patients with this disease. We will discuss the different strategies being developed to overcome these limitations that might provide for effective cellular immune therapy of CLL.

The role of prognostic factors in assessing ‘high-risk’ subgroups of patients with chronic lymphocytic leukemia

The management of chronic lymphocytic leukemia (CLL) has historically relied on 'watchful waiting' and palliative approaches to therapy. However, the course of disease is highly variable and a substantial proportion of patients with early-stage CLL develop rapidly progressive disease requiring therapy. In recent decades, numerous clinical and biological prognostic markers that are predictive of decreased survival outcomes, disease progression and/or resistance to therapy, and that may play a role in defining the subgroups of patients with 'high-risk' CLL have been identified. At the same time, highly effective treatment modalities have become available with the advent of chemoimmunotherapy combinations and allogeneic stem cell transplantation. Thus, we are approaching an era when patients with CLL may potentially benefit from individualized risk assessments based on prognostic markers and when specific therapies may be offered to the subgroup of patients with high-risk disease. This review provides a brief overview of newer biological prognostic markers, discusses the challenges associated with identifying the subgroup of patients with high-risk CLL and further aims to provide recommendations on how prognostic markers may be used to assess high-risk subgroups in different clinical situations in CLL.

A comprehensive genetic and histopathologic analysis identifies two subgroups of B-cell malignancies carrying a t(14;19)(q32;q13) or variant BCL3-translocation

The biologic and pathologic features of B-cell malignancies bearing a translocation t(14;19)(q32;q13) leading to a fusion of IGH and BCL3 are still poorly described. Herein we report the results of a comprehensive cytogenetic, fluorescence in situ hybridization (FISH), molecular and histopathological survey of a large series of B-cell malignancies with t(14;19) or variant translocations. A total of 56 B-cell malignancies with a FISH-proven BCL3 involvement were identified with the translocation partners being IGH (n=51), IGL (n=2), IGK (n=2) and a non-IG locus (n=1). Hierarchical clustering of chromosomal changes associated with the t(14;19) indicated the presence of two different groups of IG/BCL3-positive lymphatic neoplasias. The first group included 26 B-cell malignancies of various histologic subtypes containing a relatively high number of chromosomal changes and mostly mutated IgVH genes. This cluster displayed three cytogenetic branches, one with rearrangements in 7q, another with deletions in 17p and a third one with rearrangements in 1q and deletions in 6q and 13q. The second group included 19 cases, mostly diagnosed as B-cell chronic lymphocytic leukemia (B-CLL), and characterized by few additional chromosomal changes (e.g. trisomy 12) and unmutated IgVH genes. In conclusion, our study indicates that BCL3 translocations are not restricted to B-CLL but present in a heterogeneous group of B-cell malignancies.

Management of symptomatic, untreated chronic lymphocytic leukemia

Fludarabine-based regimens have become an increasingly popular first-line approach for symptomatic patients with chronic lymphocytic leukemia. Compared with chlorambucil, fludarabine alone or in combination with cyclophosphamide or rituximab yields higher response rates, higher complete remission rates, and more durable progression-free survival. Immunotherapy and chemoimmunotherapy also have the potential to increase the depth of remission as assessed by flow cytometry or molecular techniques. An overall survival advantage with any one particular regimen has not yet been demonstrated. Progress with fludarabine-based regimens, monoclonal antibodies, chemoimmunotherapy, and high-dose therapy for previously untreated patients is reviewed. Fluorescent in situ hybridization and immunoglobulin variable heavy-chain sequencing now permit more individualized risk assessment. Examples of possible treatment algorithms based on risk category are explored. How to tailor treatment based on these newer prognostic factors remains a central, as yet unanswered management question.

Predictors of improved progression-free survival after nonmyeloablative allogeneic stem cell transplantation for advanced chronic lymphocytic leukemia

Although chronic lymphocytic leukemia (CLL) remains an incurable disease with standard chemotherapy, the appropriate role and timing of transplantation are unclear. In this analysis, we report the outcomes of 46 patients with advanced CLL who underwent nonmyeloablative stem cell transplantation (NST) from HLA-matched unrelated (67%) or related (33%) donors. Fludarabine (30 mg/m2 x 4) and low-dose intravenous busulfan (0.8 mg/kg/day x 4) were used for conditioning. The 2-year overall survival (OS) and progression-free survival (PFS) rates in this refractory patient population were 54% and 34%, respectively, with a median follow-up of 20 months. The primary cause of treatment failure was relapse, with a 2-year cumulative incidence of 48%. High hematopoietic donor chimerism > or = 75% at day +30 was a significant predictor of 2-year PFS (47% vs 11%; P = .03). In multivariate analysis, chemotherapy-refractory disease at transplantation was associated with a 3.2-fold risk of progression (P = .01) and a 4.6-fold risk of death (P = .02). Increasing number of previous therapies and increasing bone marrow involvement were also associated with decreased PFS and OS. These results suggest that NST using fludarabine and low-dose intravenous busulfan is a reasonable treatment option for patients with advanced CLL, but that NST earlier in the disease course will likely be needed to achieve long-term disease control in a high proportion of patients.

Role of immunochemotherapy in the treatment of chronic lymphocytic leukemia

Major advances have been made in our understanding of the biology and opportunities for treatment of chronic lymphocytic leukemia in recent times. Newer treatment regimens incorporating purine nucleoside analogs have increased the rate of successful remission induction in chronic lymphocytic leukemia patients. Moreover, recent combination chemoimmunotherapy regimens have produced more frequent complete molecular remissions, and early evidence seems to suggest that this could result in prolonged duration of responses, although this association remains to be clearly demonstrated. This review will summarize recent advances in the biology and the management of chronic lymphocytic leukemia, including prognostic factors, pointing mainly on combination chemotherapy based on nucleoside analogs and monoclonal antibodies. In our opinion, in the future a significant improvement of clinical benefits in chronic lymphocytic leukemia will be obtained through the administration of cocktails of monoclonal antibodies combined with chemotherapy in different modalities.

Graft-versus-leukemia in chronic lymphocytic leukemia

Immune-mediated anti-leukemia effects, often termed graft-versus-leukemia (GvL), operate after bone marrow or blood cell transplants for acute lymphoblastic leukemia, acute myelogenous leukemia and chronic myelogenous leukemia. Sometimes the magnitude of this anti-leukemia effect exceeds that of high-dose anti-leukemia drugs and radiation and can result in leukemia cure. We analyzed leukemia relapse data after transplants for chronic lymphocytic leukemia (CLL) in this context. These data support the notion of a strong GvL effect in CLL. However, as most of these data are from studies of allotransplants, it is uncertain whether GvL operates in settings where the anti-leukemia effector cells and target CLL cells are genetically identical except for leukemia-related mutations. It is also uncertain whether GvL is distinct from GvHD. These potential limitations have important implications on whether immune therapy of CLL will work in non-allotransplant settings.