A scoring system for the classification of CD5-B CLL versus CD5+ B CLL and B PLL

Prognostic models for newly-diagnosed chronic lymphocytic leukaemia in adults: a systematic review and meta-analysis

BACKGROUND

Chronic lymphocytic leukaemia (CLL) is the most common cancer of the lymphatic system in Western countries. Several clinical and biological factors for CLL have been identified. However, it remains unclear which of the available prognostic models combining those factors can be used in clinical practice to predict long-term outcome in people newly-diagnosed with CLL.

OBJECTIVES

To identify, describe and appraise all prognostic models developed to predict overall survival (OS), progression-free survival (PFS) or treatment-free survival (TFS) in newly-diagnosed (previously untreated) adults with CLL, and meta-analyse their predictive performances.

SEARCH METHODS

We searched MEDLINE (from January 1950 to June 2019 via Ovid), Embase (from 1974 to June 2019) and registries of ongoing trials (to 5 March 2020) for development and validation studies of prognostic models for untreated adults with CLL. In addition, we screened the reference lists and citation indices of included studies.

SELECTION CRITERIA

We included all prognostic models developed for CLL which predict OS, PFS, or TFS, provided they combined prognostic factors known before treatment initiation, and any studies that tested the performance of these models in individuals other than the ones included in model development (i.e. 'external model validation studies'). We included studies of adults with confirmed B-cell CLL who had not received treatment prior to the start of the study. We did not restrict the search based on study design.

DATA COLLECTION AND ANALYSIS

We developed a data extraction form to collect information based on the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies (CHARMS). Independent pairs of review authors screened references, extracted data and assessed risk of bias according to the Prediction model Risk Of Bias ASsessment Tool (PROBAST). For models that were externally validated at least three times, we aimed to perform a quantitative meta-analysis of their predictive performance, notably their calibration (proportion of people predicted to experience the outcome who do so) and discrimination (ability to differentiate between people with and without the event) using a random-effects model. When a model categorised individuals into risk categories, we pooled outcome frequencies per risk group (low, intermediate, high and very high). We did not apply GRADE as guidance is not yet available for reviews of prognostic models.

MAIN RESULTS

From 52 eligible studies, we identified 12 externally validated models: six were developed for OS, one for PFS and five for TFS. In general, reporting of the studies was poor, especially predictive performance measures for calibration and discrimination; but also basic information, such as eligibility criteria and the recruitment period of participants was often missing. We rated almost all studies at high or unclear risk of bias according to PROBAST. Overall, the applicability of the models and their validation studies was low or unclear; the most common reasons were inappropriate handling of missing data and serious reporting deficiencies concerning eligibility criteria, recruitment period, observation time and prediction performance measures. We report the results for three models predicting OS, which had available data from more than three external validation studies: CLL International Prognostic Index (CLL-IPI) This score includes five prognostic factors: age, clinical stage, IgHV mutational status, B2-microglobulin and TP53 status. Calibration: for the low-, intermediate- and high-risk groups, the pooled five-year survival per risk group from validation studies corresponded to the frequencies observed in the model development study. In the very high-risk group, predicted survival from CLL-IPI was lower than observed from external validation studies. Discrimination: the pooled c-statistic of seven external validation studies (3307 participants, 917 events) was 0.72 (95% confidence interval (CI) 0.67 to 0.77). The 95% prediction interval (PI) of this model for the c-statistic, which describes the expected interval for the model's discriminative ability in a new external validation study, ranged from 0.59 to 0.83. Barcelona-Brno score Aimed at simplifying the CLL-IPI, this score includes three prognostic factors: IgHV mutational status, del(17p) and del(11q). Calibration: for the low- and intermediate-risk group, the pooled survival per risk group corresponded to the frequencies observed in the model development study, although the score seems to overestimate survival for the high-risk group. Discrimination: the pooled c-statistic of four external validation studies (1755 participants, 416 events) was 0.64 (95% CI 0.60 to 0.67); 95% PI 0.59 to 0.68. MDACC 2007 index score The authors presented two versions of this model including six prognostic factors to predict OS: age, B2-microglobulin, absolute lymphocyte count, gender, clinical stage and number of nodal groups. Only one validation study was available for the more comprehensive version of the model, a formula with a nomogram, while seven studies (5127 participants, 994 events) validated the simplified version of the model, the index score. Calibration: for the low- and intermediate-risk groups, the pooled survival per risk group corresponded to the frequencies observed in the model development study, although the score seems to overestimate survival for the high-risk group. Discrimination: the pooled c-statistic of the seven external validation studies for the index score was 0.65 (95% CI 0.60 to 0.70); 95% PI 0.51 to 0.77.

AUTHORS' CONCLUSIONS

Despite the large number of published studies of prognostic models for OS, PFS or TFS for newly-diagnosed, untreated adults with CLL, only a minority of these (N = 12) have been externally validated for their respective primary outcome. Three models have undergone sufficient external validation to enable meta-analysis of the model's ability to predict survival outcomes. Lack of reporting prevented us from summarising calibration as recommended. Of the three models, the CLL-IPI shows the best discrimination, despite overestimation. However, performance of the models may change for individuals with CLL who receive improved treatment options, as the models included in this review were tested mostly on retrospective cohorts receiving a traditional treatment regimen. In conclusion, this review shows a clear need to improve the conducting and reporting of both prognostic model development and external validation studies. For prognostic models to be used as tools in clinical practice, the development of the models (and their subsequent validation studies) should adapt to include the latest therapy options to accurately predict performance. Adaptations should be timely.

Clinical and Laboratory Features of CD5-Negative Chronic Lymphocytic Leukemia

Background

Chronic lymphocytic leukemia (CLL) usually expresses CD5 antigen. However, 7–20% of patients are CD5 negative. We report here a series of 19 CD5-negative B-CLL cases.

Material/Methods

We reviewed 19 consecutive CD5-negative B-CLL cases seen in our medical center from 2009 to 2015 and compared them with 105 CD5-positive B-CLL cases. The two groups were compared in terms of clinical parameters, laboratory parameters, and survival characteristics.

Results

Lymphadenopathy was present in 31.5% of the CD5-negative group and 51.4% of the CD5-positive group (p=0.029). Splenomegaly was present in 42.1% of the CD5-negative group and 16.1% of the CD5-positive group (p=0.029). There was no difference between the groups in terms of Binet A, B, and C stages (p=0.118, p=0.051, and p=0.882, respectively). The median thrombocyte count was 144×10⁹/L and 160×10⁹/L in the CD5-negative and CD5-positive groups, respectively (p=0.044). There was no difference between the two groups in terms of median neutrophil count (p=0.169). The mean lymphocyte count was 43.2±4.0×10⁹/L and 36.7±3.2×10⁹/L in the CD5-negative and CD5-positive groups, respectively (p=0.001). There was no difference between the groups in terms of autoimmune hemolytic anemia and autoimmune thrombocytopenia. In five-year follow-up, 84.2% of CD5-negative patients and 90.5% of CD5-positive patients were alive (p=0.393).

Conclusions

We found more isolated splenomegaly, less lymphadenopathy, a higher lymphocyte count, and a lower thrombocyte count in the CD5-negative group. There was no difference between the groups in terms of clinical stage, autoimmune phenomena, hemoglobin and neutrophil count, and survival.

A multicenter retrospective clinical study of CD5/CD10-negative chronic B cell leukemias

CD5-negative chronic B cell lymphoproliferative disorders in leukemic phase (B-CLPD) are heterogeneous and relatively uncommon pathologies that often lack a histopathological definition because of the absence of accessible pathological tissue. We describe the clinical features and evolution-related variables of 156 patients with CD5/CD10-negative B-CLPD (median age 66 years, range 25-86). The median follow-up was 51 months (range 6-216), and overall 3- and 5-year survival was respectively 87 and 76%; 50 patients needed therapy at diagnosis, 56 during follow-up, and 50 remained untreated until the last control. A combined clinical, histological, cytomorphological, immunophenotypical, and cytogenetic diagnostic approach allowed the complete classification of only a minority of patients as being affected by splenic marginal zone or lymphoplasmacytic lymphoma; the majority of cases remained unclassifiable. Multivariate analysis showed that the clinicohematological variables adversely related to overall survival were serum LDH levels and age, whereas high serum LDH levels, hemoglobin levels of <11 g/dl, and splenomegaly related to treatment-free time (in "wait and see" cases); only splenomegaly related to time to progression (in treated patients). In conclusion, our retrospective study describes the clinical features and variables related to evolution in a large group of patients with CD5/CD10-negative chronic B-cell lymphoid leukemias and underlines the fact that a probable lymphoplasmacytic or marginal zone normal cell origin can be supposed in such leukemic forms, but never surely demonstrated.

Cell surface CD43 determination improves diagnostic precision in late B-cell diseases

Panels of immunological markers are useful in refining diagnosis in view of certain variability between B-cell leukaemias. A statistical multivariate approach was used on 100 B leukaemias (preliminary sample) to explore the potential value of the combination of CD43, and the classical markers CD5, CD23, CD79b, FMC7, CD22 and surface immunoglobulin to differentiate chronic lymphoid leukaemia (CLL) from lymphoma (non-CLL). CD43 was highly effective (P < 0.00001) and its inclusion in the panels improved the accuracy of discrimination in a 'control' sample of 74 B leukaemias to 98.6%. Inclusion of CD43 facilitates the diagnosis of B-lymphoproliferative disorders and improves their classification.

Diagnostic role and prognostic significance of a simplified immunophenotypic classification of mature B cell chronic lymphoid leukemias

We verified the diagnostic and prognostic role of a simplified immunophenotypic classification (IC) in a series of 258 patients (M/F: 1.4; median age: 64 years; median follow-up: 64 months; 75 deaths) with mature B cell lymphoid leukemias (MBC-LL) for whom no histopathological diagnosis was available because of minimal or no lymph node involvement. The IC was based on the reactivity of three pivotal immunophenotypic markers: CD5, CD23 and SIg intensity. On the basis of different expression patterns, we identified four diagnostic clusters (C) characterized by distinct clinico-biological features and different prognoses: C1 (149 patients) identified most classical B cell chronic lymphocytic leukemias (CLL-type cluster; SIg(dim)/CD5+/CD23+); C2, 38 patients whose clinico-hematological characteristics were intermediate between C1 and C3 (CLL-variant cluster; SIg(bright)/CD5+/CD23+/-or SIg(dim)/CD5-/-/CD23 indifferent); C3 (16 patients) most situations consistent with mantle cell lymphoma in leukemic phase (MCL-type cluster; SIg(bright)/CD5+/CD23-); and C4, 55 cases, most of whom were consistent with leukemic phase lymphoplasmacytic/splenic marginal zone lymphomas (LP/S-type cluster; SIg(bright)/CD5-/+/CD23 indifferent). At univariate survival analysis, prognosis worsened from C1 to C4, C2 and C3 (P = 0.0001), and this was maintained at multivariate analysis (P = 0.006), together with CD11c expression (P = 0.0043), age at diagnosis (cut-off 70 years; P = 0.0008) and platelet count (cut-off 140 x 10(9)/l; P = 0.0034). Besides recognising the two well-known situations of classic B-CLL and MCL, our IC identified situations with distinct prognostic and/or clinical behaviors.

Differentiation of monoclonal B lymphocytosis of undetermined significance (MLUS) and chronic lymphocytic leukemia (CLL) with weak CD5 expression from CD5(-) CLL

Chronic lymphocytic leukemia (CLL) is recognized as a unique lymphoproliferative disorder of CD5(+) B cells. However, many published series of CLL included a subgroup of CD5(-) cases. CD5(-) B cell CLL is a topic of controversy and its nature and true incidence remain unclear. We in this study performed a retrospective analysis of a total of 128 consecutive patients with a diagnosis of CLL and available immunophenotypic record. Of these, 14 cases were previously considered CD5(-) CLL. From a further analysis of clinical, hematological and immunophenotypic results, we have reclassified seven of the patients as having weak or dim expression of CD5 and four patients as being monoclonal B lymphocytosis of undetermined significance (MLUS). The remaining three cases had clinical and morphological features consistent with prolymphocytic leukemia (PLL) or mixed CLL/PLL. Our results suggest that the CD5(-) phenotype probably does not qualify for CLL. Previous CD5(-) CLL may include false negatives due to heterogeneity of the intensity of CD5 expression, CD5(-) MLUS and variant CLL; the latter likely represents CLL in transformation. All the patients with MLUS were found to have a mild and non-progressing lymphocytosis with CD5(-) phenotype. These features may be used to differentiate them from CLL.

CD5-negative, CD10-negative small B-cell leukemia: variant of chronic lymphocytic leukemia or a distinct entity?

CD5- and CD10-negative chronic lymphocytic leukemias are quite uncommon as compared to the CD5-positive CLL. We reviewed 250 sequential cases of peripheral blood lymphocytosis to characterize cases of small B-cell lymphoproliferative disorders, submitted with a clinical diagnosis of chronic lymphocytic leukemia exhibiting a non-classic immunophenotypic profile. Six cases of CD5-, CD10-negative chronic lymphocytic leukemias and no tissue involvement were identified that revealed high-density surface-membrane immunoglobulin and CD20 expression, with variable expression of CD11c, CD23, and CD25. Most had a profound leukocytosis (mean WBC 180 x 10(9)/L) with proliferation of mature-appearing lymphocytes. Subsequent bone marrow biopsies showed diffuse infiltration by neoplastic cells in all evaluated patients. The clinical course appeared indolent, with follow-up revealing three patients alive (survival time 38-68 months), while two died of unrelated causes and one was lost to follow-up soon after diagnosis. These cases may represent somewhat unusual chronic lymphoproliferative disorders, with morphologic features and immunophenotypic profile not readily classifiable, but which are certainly atypical for classic chronic lymphocytic leukemia. Some of these features are reminiscent of those seen in marginal-zone lymphoma. However, it is most unusual for this known to be tissue-based disease to present primarily as leukemia rather than lymphoma.

B-chronic lymphocytic leukemia: practical aspects

B-CLL is the most common adult leukemia in the Western world. It is a neoplasia of mature looking B-monoclonal lymphocytes co-expressing the CD5 antigen (involving the blood, the bone marrow, the lymph nodes and related organs). Much new information about the nature of the neoplastic cells, including chromosomal and molecular changes as well as mechanisms participating in the survival of the leukemic clone have been published recently, in an attempt to elucidate the biology of the disease and identify prognostic subgroups. For the time being, clinical stage based on Rai and Binet staging systems remains the strongest predictor of prognosis and patients' survival, and therefore it affects treatment decisions. In the early stages treatment may be delayed until progression. When treatment is necessary according to well-established criteria, there are nowadays many different options. Chlorambucil has been the standard regimen for many years. During the last decade novel modalities have been tried with the emphasis on fludarabine and 2-chlorodeoxyadenosine and their combinations with other drugs. Such an approach offers greater probability of a durable complete remission but no effect on overall survival has been clearly proven so far. Other modalities, included in the therapeutic armamentarium, are monoclonal antibodies, stem cell transplantation (autologous or allogeneic) and new experimental drugs. Supportive care is an important part of patient management and it involves restoring hypogammaglobulinemia and disease-related anemia by polyvalent immunoglobulin administration and erythropoietin respectively.

Adhesion molecule expression in CD5-negative/CD10-negative chronic B-cell leukemias: comparison with non-Hodgkin's lymphomas and CD5-positive B-cell chronic lymphocytic leukemia

The classification of CD5-negative/CD10-negative chronic B-cell leukemias (CD5-/CD10- CBL) can be problematic. Most of these cases may represent leukemic non-Hodgkin's lymphoma (NHL) other than B-cell chronic lymphocytic leukemia (BCLL); nonetheless, some investigators still advocate the term "CD5-negative BCLL." Because adhesion molecule (AdMol) expression patterns reflect the biology of lymphoid neoplasms, we studied a series of 106 B-cell lymphoproliferative disorders, including CD5+ BCLL (n = 56), NHL other than BCLL (n = 35), and CD5-/CD10- CBL (excluding hairy cell leukemia and prolymphocytic leukemia) with no prior history of NHL (n = 15) for expression of components of the very late antigen-4 complex (alpha4/beta1 integrin (CD49d/CD29)), components of the mucosal addressin-cell adhesion molecule receptor (alpha4(CD49d)/beta7 integrin), and L-selectin (CD62L). CD62L expression was significantly greater in CD5+ BCLL than in NHL (P < .001). Conversely, CD29, CD49d, and beta7-integrin expression were significantly greater in NHL than in CD5+ BCLL (P < .001 for each marker). These differences persisted when only blood and bone marrow samples were analyzed, with the exception of differences in CD62L expression, which approached, but did not reach, statistical significance (P = .08). The group of CD5-/CD10- CBL displayed an AdMol profile similar to NHL and was significantly different than CD5+ BCLL in expression of beta7 integrin, CD29, CD49d, and CD62L (P range < .001-.011). In summary, CD5-/CD10- CBL display an AdMol profile resembling NHL and significantly different from CD5+ BCLL, supporting the growing notion that "CD5-negative BCLL" generally represents leukemic NHL rather than a variant of true CD5+ BCLL.

Analysis of the immunoglobulin heavy chain gene variable region of 101 cases with peripheral B cell neoplasms and B cell chronic lymphocytic leukemia in the japanese population

We have analyzed the immunoglobulin heavy chain (VH) gene variable regions (CDR2 and FW3) of 101 Japanese cases with peripheral B cell neoplasms. When all except one case with a deletion were graphed by frequency of replacement mutation, the 100 cases could be separated into two groups: 24 cases with zero, one and two mutations (germline or low frequency of somatic mutation); and 76 cases with three or more mutations (medium to high frequency of somatic mutation). While most mantle cell lymphoma cases (11/13) showed germline or low frequency of somatic mutation, all cases of mucosa-associated lymphoid tissue (MALT) lymphoma (11/11), follicular lymphoma (three of three cases), plasma cell myeloma (seven of seven cases) and most cases of diffuse large B cell lymphoma (DLBCL; 42/47) belonged to the latter group. These 76 cases, therefore, may be considered to show somatic hypermutation. More than half of chronic lymphocytic leukemia/small lymphocytic lymphoma cases (CLL/SLL; eight of 13) showed a hypermutated VH gene and the ratio of replacement mutation: silent mutation in CDR2 of CLL/SLL was considerably higher compared with DLBCL and MALT lymphoma, showing somatic hypermutation. When comparing VH gene type of B cell-CLL (B-CLL) among our series and those in the literature, more cases of CD5+ B-CLL in the Western literature have the VH5 and VH6 family types, while more cases in Japan are reported to have VH4 family. The occurrence of VH families in B-CLL between Japanese and Western people seems to be comparable.

Deletion 7q in B-cell low-grade lymphoid malignancies: a cytogenetic/fluorescence in situ hybridization and immunopathologic study

Ten cases presenting a simple karyotype and del(7q) as a primary event were selected out of 353 patients referred as B-cell low-grade malignant lymphoproliferative disorders. Chromosome 7-specific painting probes confirmed the deletion that was tentatively assigned to bands q31q35. Chromosome 7 was involved in an interstitial deletion in seven cases, in an unbalanced translocation in two cases, and in a ring chromosome in one case. Common clinical/hematological features included advanced age, marked splenomegaly, and peripheral blood monoclonal IgM(D) lymphocytosis. Regardless of morphologic entity, most cases shared lymphoplasmacytoid features. Deletion 7q may delineate a variety of low-grade B-cell lymphoid disorders characterized by a common clinical history and immunopathologic similarities. The cytogenetic pattern and the ongoing work on molecular mapping of this deletion suggest that the loss of a putative tumor-supressor gene at 7q31q32 may constitute an early event in their pathogenesis.

CD5 negative B-cell chronic lymphocytic leukemia: clinical and biological features of 42 cases

Chronic lymphocytic leukemia cell (CLL) usually (95%) express B-phenotype and the CD5 antigen which is usually present on the surface of normal T cells. However, among B CLL, 7 to 20% do not express CD5. The significance of the lack of CD5 expression remains unclear. We reviewed 42 consecutive CD5- B CLL seen in three French medical centers from 1985 to 1991 and compared them with 79 CD5+ B CLL. Immunophenotype studies were performed using indirect immunofluorescence under light microscopy as well as flow cytometry after 1988. B CLL was considered to be CD5 negative when less than 5% of mononuclear cells expressed CD5 after subtraction of the number of T-cells. Cases with CD5- B CLL had isolated splenomegaly more frequently (p = 2.10(-7)). They frequently expressed a higher level of surface immunoglobulin (S-Ig) or the switch mu/delta phenotype (p = 4.7 10(-2)). The median survival time was not reached but no significant difference between CD5 negative and positive B CLL was observed at the time of our data analysis (p = 0.97). Clinical presentation of CD5- B CLL seems to be different from other forms of B CLL. Although, no conclusion can be reached in terms of prognosis, CLL with low expression of CD5 should be regarded as a subtype of CLL with a different clinical presentation than CD5+ CLL.

Genetic abnormalities in chronic lymphocytic leukemia and their clinical and prognostic implications

Clonal chromosome abnormalities can be detected in approximately 50% of patients with chronic lymphocytic leukemia (CLL). The most common changes are trisomy 12, followed by structural abnormalities of 13q, 11q, 6q, and 14q. By fluorescence in situ hybridization (FISH), these aberrations can be demonstrated even in cases with insufficient mitotic yield or a normal karyotype. The biologic consequences of trisomy 12 are unknown, but a gene dosage effect is suspected and studies on partial trisomy 12 indicate that the region 12q13 to 12q22 might be of particular pathogenetic importance. Trisomy 12 is strongly associated with atypical lymphocyte morphology and seems to be a secondary event in leukemogenesis, as shown by combined immunophenotyping and interphase FISH. Structural abnormalities of 13q frequently involve hetero- and homozygous deletions of a region in 13q14, distal to the retinoblastoma gene, which may be the site of a tumor suppressor gene. In contrast to a normal karyotype or structural changes of 13q, complex karyotypic abnormalities, high percentage of abnormal metaphases, trisomy 12 and structural changes involving the P53 tumor suppressor gene on 17p13 are adverse prognostic indicators. Cytogenetic and molecular findings provide important diagnostic, clinical, and prognostic information which can contribute to treatment decisions and follow-up of CLL patients.

VH gene expression in CD5 positive and CD5 negative B cell chronic lymphoid malignancies

In this review, we report analyses of VH genes in mature B cell malignancies generally or occasionally bearing CD5 antigen such as B CLL, MCL, SLVL and PLL. In the majority of cases, B CLL and MCL use VH genes in germline configuration. However in some cases a higher rate of random mutations is observed. These differences are not related to CD5 expression but are accounted by Ig phenotype, since less mutations are observed in CLL cases expressing membrane mu delta, when compared to forms exclusively expressing membrane mu. PLL and SLVL cases display mutated V genes independently of CD5 expression. Although there is some evidence that CD5+ B cells constitute a separate lineage, the possibility that CD5 constitutes an activation marker cannot be ruled out. Indeed, CD5- B cells can be induced to differentiate into CD5+ B cells and VH gene analyses showed no significative differences between CD5+ and CD5- B cell lymphoproliferative disorders. In this review we have tried to examine B cell chronic malignancies on the basis of phenotype and VH gene usage. Thus we propose a tentative classification where these disorders are allocated according to these characteristics.

The value of the monoclonal antibody, DBA44, in the diagnosis of B-lymphoid disorders

The DBA44 monoclonal antibody described by Al Saati recognizes a membrane antigen expressed by a sub-population of B-lymphocytes. It was tested on paraffin-embedded tissues, and it distinguishes Hairy Cell Leukemia (HCL) from the more common B-cell Chronic Lymphocytic Leukemia (CLL). Neither Splenic Lymphoma with Villous Lymphocytes (SLVL) cases nor Prolymphocytic Leukemia (PLL) cases were tested. We have tested 87 B-lymphoproliferative disorders with DBA44 on cytocentrifuge preparations. All five HCL cases were positive (100%). Of 24 cases of SLVL, 19 were positive (79%); of 58 other B-cell malignancies, five cases were positive (8.5%), including 1/8 CD5- CLLs, 1/5 PLLs and 3/24 lymphomas. All CD5+ CLL were negative. DBA44 positivity cannot distinguish HCL from SLVL, which is the disease that may create major diagnostic problems. In contrast, when we compare SLVL to CLL (which is another diagnostic problem), significant differences were found between the incidence of DBA44 positivity in SLVL and both CD5+ B-CLL (p< 10(-5)), and CD5- B-CLL (p< 0.01). The monoclonal antibody DBA44 is positive in HCL and SLVL. It is not helpful in the differential diagnosis of HCL and SLVL. In contrast, when a diagnostic problem arises between SLVL and CLL, the reactivity of DBA44 is of great value.