All-inside repair of meniscal bucket handle tears: a retrospective study at mean 4-years follow-up evaluation.

Bucket-handle tears represent approximately 10% of all meniscal tears. Despite the common treatment is subtotal meniscectomy, repair is technically feasible although complex, and represents a key strategy to avoid severe meniscal tissue loss that could accelerate joint degeneration over time. The aim of this retrospective study was to determine the outcomes of arthroscopically-assisted bucket-handle tear repair, and to identify factors correlating with clinical results. Fifty-four patients affected by meniscal bucket handle tear were included in the present retrospective analysis and evaluated up to mean 4-years follow-up. All patients were treated by arthroscopic-assisted all-inside repair. The primary outcome was considered the need for a re-operation due to failure of meniscal repair. Patients were also evaluated by the following items: KOOS, Lysholm, Tegner, IKDC-subjective and Quadruple-VAS score. Subgroup analysis was performed to identify whether concurrent ACL reconstruction, side of the lesion, age at surgery and time from injury to repair could influence clinical outcome. Ten out 54 patients (18.5%) were considered failed and needed reoperation, mainly within one year from surgery. Overall, there was a significant increase in all clinical scores considered and patients were able to get back to previous sport activity level. Patients with concurrent ACL reconstruction presented a lower risk of failure (p=0.025). Patients with lateral meniscus repair showed better clinical outcome compared to medial meniscus. Timing from injury and age at surgery did not correlated with clinical outcome. Our series showed fair results in bucket handle repair up to middle term evaluation. Concomitant ACL reconstruction was associated with lower failure rate whereas lateral meniscus involvement was associated with higher functional scores at final follow-up evaluation.

Tantalum in type IV and V Paprosky periprosthetic acetabular fractures surgery in Paprosky type IV and V periprosthetic acetabular fractures surgery.

PURPOSE: Periprosthetic acetabular fractures represent a growing and serious complication of total hip arthroplasty (THA). The purpose of the study is to report our experience in the use of tantalum for the treatment of Paprosky type IV and V periprosthetic acetabular fractures. METHOD: We analyzed 24 patients with type IV and V periprosthetic acetabular fractures. Patients were treated with a revision surgery using tantalum components, in some cases in association with posterior plating. Outcomes were evaluated using VAS, Harris hip score and considering the average time of integration of the acetabulum and the number of complications. The endpoint evaluation was established at 24 months. RESULT: Results show that the average time of integration of the neoacetabulum in tantalum was 12.3 months (range 6-18 months). The average VAS pain is 8.7/10 cm at time 0 and gradually returns to basic pre-injury values in the following months. The average value of HHS at time 0 is 13.5 points. This value tends to increase progressively until reaching a mean score of 89.3 points at 24 months, higher than the average pre-trauma value of 84.3 points. CONCLUSION: Periprosthetic fractures of the acetabulum with bone loss are a rare but potentially disastrous complication of total hip prostheses. Their management and therapeutic choice will test the ability of the orthopedic surgeon. It is important to determine the type of fracture and characteristics in order to pursue an adequate therapeutic strategy. The modern biomaterials, such as porous tantalum, offer a greater potential in replacing bone loss, promoting bone regrowth and obtaining a stable implant.

Non-infusional vs intravenous consolidation chemotherapy in elderly patients with acute myeloid leukemia: final results of the EORTC-GIMEMA AML-13 randomized phase III trial.

In this trial, acute myeloid leukemia patients (pts) aged 61-80 years received MICE (mitoxantrone, etoposide and cytarabine) induction chemotherapy in combination with different schedules of granulocyte colony-stimulating factor administration. Pts in complete remission were subsequently randomized for two cycles of consolidation therapy: mini-ICE regimen (idarubicin, etoposide and cytarabine) given according to either an intravenous (i.v.) or a 'non-infusional' schedule. Among the 346 pts randomized for the second step, 331 pts received consolidation-1 and 182 consolidation-2. A total of 290 events (255 relapses, 35 deaths in first CR) have been reported. The median follow-up was 4.4 years. No significant differences were detected in terms of disease-free survival (median 9 vs 10.4 months, P=0.15, hazard ratio (HR) =1.18, 95% confidence interval (CI) 0.94-1.49) - primary end point - and survival (median 15.7 vs 17.8 months, P=0.19, HR=1.17, 95% CI 0.92-1.50). In the 'non-infusional' arm grade 3-4 vomiting (10 vs 2%; P=0.001) and diarrhea (10 vs 4%; P=0.03) were higher than in the 'i.v.' arm, whereas time to platelet recovery >20 x 10(9)/l (median: 19 vs 23 days; P=0.02) and duration of hospitalization (mean: 15 vs 27 days; P<0.0001) was shorter. The 'non-infusional' consolidation regimen resulted in an antileukemic effect similar to the intravenous regimen, which was less myelosuppressive and associated with less hospitalization days.

Gemtuzumab ozogamicin (Mylotarg) as single-agent treatment for frail patients 61 years of age and older with acute myeloid leukemia: final results of AML-15B, a phase 2 study of the European Organisation for Research and Treatment of Cancer and Gruppo Italiano Malattie Ematologiche dell'Adulto Leukemia Groups.

The therapeutic activity and toxicity profile of gemtuzumab ozogamicin were assessed in 40 patients >60 years of age with acute myeloid leukemia (AML) who were not considered eligible for conventional chemotherapy because of advanced age or poor performance status. The drug was administered at the dose of 9 mg/m2 as a single 2-h i.v. infusion on days 1 and 15. Patients who achieved a complete remission (CR/CRp) were to receive a consolidation with two additional injections of the immunotoxin at the same dose. The overall CR/CRp rate was 17% (95% CI, 8-32%). The CR/CRp rate in patients 61-75 years old was 33% (6/18), and 5% (1/22) in patients older than 75 years. Induction death occurred in seven patients (17%), all aged above 75 years. Overall survival was significantly longer in patients aged 61-75 years than in older individuals (P=0.05), and in CD33+ cases than in CD33- cases (P=0.05). We conclude that the dose/schedule of gemtuzumab ozogamicin used in this trial is too toxic in the age group over 75 years. For these patients, additional studies with reduced doses of the immunotoxin are warranted.

CD56 expression is an indicator of poor clinical outcome in patients with acute promyelocytic leukemia treated with simultaneous all-trans-retinoic acid and chemotherapy.

PURPOSE: Preliminary reports suggest that leukemic cell expression of CD56, a neural cell adhesion molecule, is associated with adverse clinical outcome in either acute myeloid leukemia with t(8;21) or acute promyelocytic leukemia (APL). We investigated the prognostic relevance of CD56 in a series of patients with APL who were treated homogeneously with all-trans-retinoic acid (ATRA) and chemotherapy. PATIENTS AND METHODS: Clinicobiologic presenting features and therapeutic results were analyzed in a series of 100 patients with genetically proven APL who were treated, according to the example of the Gruppo Italiano Malattie Ematologiche Maligne dell'Adulto multicenter trial, with ATRA plus idarubicin (AIDA) and for whom data on CD56 expression were available at diagnosis. RESULTS: Fifteen patients (15%) showed expression of CD56 in greater than or equal to 20% blasts at diagnosis and were considered as CD56(+). No differences were found regarding age, sex, WBC and platelet counts, incidence of coagulopathy, hemoglobin and fibrinogen levels, promyelocytic leukemia/retinoic acid receptor (PML/RAR) alpha fusion type, or complete remission (CR) rate in the comparison of the CD56(+) and CD56(-) populations. Conversely, compared with patients who were CD56(-), patients with CD56(+) APL had shorter CR duration (P =.04) and overall survival (P =.002). In the multivariate analysis, CD56 positivity and initial WBC count greater than 10 x 10(9) cells/L retained statistical significance in overall survival (P =.04 and P =.02, respectively). CONCLUSION: The expression of CD56 is significantly associated with inferior CR duration and survival in patients with APL who were treated with modern frontline treatment that included ATRA and simultaneous chemotherapy. Combined with other well-established prognostic factors such as WBC count, CD56 expression at diagnosis might be used to build prognostic scores for risk-adapted therapy in APL.

Modulation of purine analogs- and chlorambucil-induced cytotoxicity by alpha-interferon and interleukin-2 in chronic lymphocytic leukemia.

The decrease in cell viability observed in vitro from the effect of chlorambucil (CLB), fludarabine (FAMP) and 2-chlorodeoxy-adenosine (CDA) on peripheral lymphocytes from 49 untreated CLL patients was investigated by the MTT colorimetric assay. The effects of recombinant-interleukin (r-IL)-2 and alpha-interferon (alpha-IFN) on drug-induced cell death were evaluated. r-IL-2 significantly increased in vitro resistance to CLB, while purine analog cytotoxicity was slightly reduced by the cytokine. The potential in vivo significance of r-IL-2, acting as a survival signal on CLB-induced cell death, is supported by the correlation between the lowest IL-2 serum levels, the highest in vitro sensitivity to CLB and a major clinical response after CLB treatment in six out of eight CLL patients. Using 25 samples, alpha-IFN enabled CLL cells to increase resistance to CLB, CDA and FAMP in 14, eight and seven samples, respectively; conversely, alpha-IFN showed a synergism with both CLB and FAMP in six samples and with CDA in four. These results correlate with immunoenzymatic assay data showing that alpha-IFN either up- or down-regulates tumor necrosis factor and IL-1 levels in supernatants of some CLL samples. Apparently, alpha-IFN plays a dual role in regulating drug-induced cell death, while IL-2 seems to solely favor cell survival in CLL.

Alpha 2-interferon in B-cell chronic lymphocytic leukemia: clinical response, serum cytokine levels, and immunophenotype modulation.

Fifteen patients with B-cell chronic lymphocytic leukemia (B-CLL) have been treated with alpha 2b-interferon (alpha IFN) for one year (3 mega units subcutaneously three times a week). The hematological response and the modulation of immunophenotype, serum levels of soluble interleukin-2 receptor (sIL-2R) and tumour necrosis factor (TNF) have been monitored. Hematologically 67% of cases were classified as responders, although no complete responses were observed; three cases progressed during treatment, and two patients showed stable disease. Both peripheral lymphocytes and CD24+ cell absolute number significantly decreased after twelve months of IFN treatment (40.7 +/- 17 x 10(9)/l versus 15.8 +/- 6 x 10(9)/l, mean values +/- sd, p < 0.01, and 30.4 +/- 5.5 x 10(9)/l versus 8.1 +/- 2.8 x 10(9)/l, p < 0.05, respectively), while CD24+ cell percentage did not change (72.1% +/- 4.6 versus 67.5% +/- 8.8, p not significant). In the majority of cases myelomonocytic markers (CD11c, CD14, CD11b) transitorily decreased during the treatment. Serum sIL-2R levels, elevated in all cases before IFN treatment, increased in responders. Serum TNF levels decreased in patients showing high values before the treatment. The explanation of these findings and their possible implication are discussed.

Treatment of elderly patients (> or =60 years) with newly diagnosed acute promyelocytic leukemia. Results of the Italian multicenter group GIMEMA with ATRA and idarubicin (AIDA) protocols.

In all, 134 elderly patients (median age 66 years, range 60-75 years) with newly diagnosed acute promyelocytic leukemia (APL) were enrolled in two successive protocols of the Italian multicenter group GIMEMA. All patients received an identical induction with all-trans retinoic acid and idarubicin; 116 (86%) entered complete remission (CR), two (2%) were resistant and 16 (12%) died during induction. After CR, 106 patients received further therapy whereas 10 did not, because of refusal (n=5) or toxicity (n=5). Consolidation consisted of three chemotherapy courses in the AIDA protocol (AIDA, 67 patients) or, since 1997, of an amended protocol including only the first cycle (amended AIDA, aAIDA, 39 patients). In the AIDA group, 43 patients (64%) completed consolidation, while seven (11%) and 17 (25%) patients were withdrawn after first and second courses, respectively; nine patients (13%) died in CR and 12 (18%) relapsed. In the aAIDA group, all patients received the assigned treatment; two patients (5%) died in CR and six (15%) relapsed. In the AIDA and aAIDA series, the 3-year overall and discase-free survival rates were 81 and 83% (P=NS), 73 and 72% (P=NS), respectively. We highlight here the frequency and severity of complications linked to intensive chemotherapy in this clinical setting and suggest that, in APL of the elderly, less intensive postremission therapy allows significant reduction of severe treatment-related toxicity and may be equally effective.

Outcome of patients with acute myeloid leukemia who failed to respond to a single course of first-line induction therapy: a GIMEMA study of 218 unselected consecutive patients. Gruppo Italiano Malattie Ematologiche Maligne dell'Adulto.

The outcome of a cohort of 218 consecutive patients who failed to respond to a single course of standard daunorubicin plus ARAC (three + seven) induction regimen has been retrospectively evaluated to assess the characteristics of this group of AML patients and the effectiveness of second-line induction programs. Seventy-four of the 218 patients (33.9%) attained complete remission with salvage chemotherapies. The multivariate analysis of pretherapy characteristics of the patients showed that peroxidase positivity and age were the most important factors in determining whether or not the patient would have a favorable response to second-line induction regimen. In addition, comparison of marrow characteristics at diagnosis with those of marrow after the first-line therapy (marrow leukemic index, MLI) provided the greatest differences between second-line CR and resistant patients. Finally, peroxidase positivity and MLI predicted for remission duration and overall survival. Allogeneic BMT, however, appeared the most important factor for survival and event-free survival of remitting patients. These results are of importance when considering that better defined prognostic factors provide an objective rationale for selecting appropriate strategies for the treatment of patients who do not respond to a single course of induction regimen.

Successful mobilization of PBSCs predicts favorable outcomes in multiple myeloma patients treated with novel agents and autologous transplantation.

Incorporation of novel agents into auto-SCT for patients with multiple myeloma has led to improvement in their outcomes. However, the effects of new drugs, either single or combined, on PBSC mobilization have not been fully evaluated, particularly in phase 3 clinical studies. We analyzed the impact of two novel agent-based induction treatments in patients enrolled in the GIMEMA MMY-3006 study comparing bortezomib, thalidomide and dexamethasone (VTD) versus thalidomide and dexamethasone (TD) in preparation for double auto-SCT. Results showed that a short-term induction therapy with VTD did not adversely affect CD34(+) cell yields as compared with TD (9.75 vs 10.76 × 10(6) CD34(+) cells/kg, P=0.220). For poor mobilizers (<4 × 10(6) CD34(+) cells/kg), 5-year rates of time to progression (TTP), progression-free survival (PFS) and overall survival (OS) were significantly shorter than for successful mobilizers (TTP:17 vs 48%, P<0.0001; PFS: 16 vs 46%, P<0.0001; OS: 50 vs 80%, P<0.0001). These differences were retained across patients randomized to the TD arm; conversely, no differences in outcomes were seen in patients treated with VTD, irrespective of the number of harvested CD34(+) cells. The number of collected PBSCs predicted better outcomes after auto-SCT and VTD overcame the negative impact of a poor stem cell mobilization.

Diagnostic and prognostic relevance of the immunophenotype in acute myelocytic leukemia.

The immunophenotype of 72 cases with acute myelocytic leukemia was investigated with a panel of monoclonal antibodies. When the morphologic criteria of the FAB classification was compared with the normal myeloid and erythroid pathway of differentiation identified by MoAbs, a relationship was found with FAB M5 and M6. Moreover, a constant negativity to HLA-DR and CD15 antigens in M3 and the contemporaneous expression of HLA-DR and CD11b antigens on the M4 and M5 leukemic cells were observed. We identified phenotypically distinct groups of patients with different responses to therapy. In fact, patients whose leukemic cells did not express the HLA-DR antigen showed, in a univariate analysis, a significantly higher percentage of complete remissions than did HLA-DR-positive patients. Multivariate discriminant analysis, in line with this result, showed that the parameters of discriminant capacity were, in order of statistical significance, young age, low WBC count and the lack of DR expression, respectively. A trend for a better response to therapy, without any statistical relevance, was also observed in CD11b-negative and CD33-positive cases. Similar results were detected in patients who expressed either DR or CD11b, or none of these markers. These findings indicate that immunophenotype may identify some FAB subtypes. Moreover, in some cases the phenotypic profile can provide useful information about the clinical outcome.

An active strain electromechanical model for cardiac tissue.

We propose a finite element approximation of a system of partial differential equations describing the coupling between the propagation of electrical potential and large deformations of the cardiac tissue. The underlying mathematical model is based on the active strain assumption, in which it is assumed that there is a multiplicative decomposition of the deformation tensor into a passive and active part holds, the latter carrying the information of the electrical potential propagation and anisotropy of the cardiac tissue into the equations of either incompressible or compressible nonlinear elasticity, governing the mechanical response of the biological material. In addition, by changing from a Eulerian to a Lagrangian configuration, the bidomain or monodomain equations modeling the evolution of the electrical propagation exhibit a nonlinear diffusion term. Piecewise quadratic finite elements are employed to approximate the displacements field, whereas for pressure, electrical potentials and ionic variables are approximated by piecewise linear elements. Various numerical tests performed with a parallel finite element code illustrate that the proposed model can capture some important features of the electromechanical coupling and show that our numerical scheme is efficient and accurate.

Comparison of younger versus older B-cell chronic lymphocytic leukemia patients for clinical presentation and prognosis. A retrospective study of 53 cases.

Fifty-three patients affected with B-cell chronic lymphocytic leukemia (CLL) younger than 50 years and observed in two hematological institutions have been retrospectively evaluated in order to verify whether this disease has different clinico-hematological features at presentation and different prognosis as compared to older cases. In our experience young cases with B-CLL diagnosis, confirmed by immunophenotype in 90.5% of patients, accounted for 7.1% of the whole CLL population. Sex distribution, mean peripheral lymphocyte count, platelet count, distribution among Rai's and Binet's stages, total tumor mass (TTM) score, histological pattern of bone marrow infiltration and lymphocyte doubling time (LDT) were similar to a series of 201 CLL cases older than 50 years. Only hemoglobin mean level was significantly higher in younger patients (13.1 +/- 2.1 vs 12.2 +/- 2.6 g/dl; p < 0.01). The overall median survival was 7.1 years. Rai and Binet staging classifications and TTM score system retained their prognostic value in this CLL population. In addition, cases fulfilling criteria of "smoldering" CLL, had a very long survival (75% survival probability at 16 years). Life-expectancy of younger patients was significantly longer than that of older ones (median survival, 7.1 versus 4.1 years; p < 0.05). However, when the background mortality due to non-CLL related deaths (i.e., cardiovascular complications, epithelial cancers) was removed, survival advantage of young cases disappeared. In conclusion this study confirms that prognosis of young CLL patients can be easily assessed using the current well-defined criteria. Since age is not by itself a criterion for intensifying treatment, further efforts to identify those young CLL patients who qualify for more aggressive therapy should be made.

In vitro chemosensitivity of chronic lymphocytic leukemia B-cells to multidrug regimen (CEOP) compounds using the MTT colorimetric assay.

BACKGROUND: Anthracycline-containing regimens have given controversial clinical results in CLL. Therefore, we explored the in vitro behavior of CLL B-cells after exposure to the compounds included in the most frequently used combination therapy regimen (CEOP). METHODS: A 4-day MTT colorimetric assay was used in vitro to test the effect of CEOP regimen drugs, either alone or in combination, on CLL B-cells. All drugs but mafosfamide, tested in place of cyclophosphamide, were used at concentrations corresponding to the in vivo dosage employed in the CEOP regimen. Chlorambucil was also studied since it represents the standard treatment for this disease. RESULTS: Epirubicin, prednisone and vincristine displayed a cytotoxic effect in 15, 13 and 4 out of 30 samples, respectively. Combinations of the same drugs showed a synergistic effect in 6 out of 13 assays. A cytotoxic effect of chlorambucil was detected in 2 out of 5 responders to the combination of CEOP regimen drugs, and in 3 out of 7 non responders. Mafosfamide induced a reduction in cell survival in 60-80% of the samples, depending on its concentration. CONCLUSIONS: The MTT assay is suitable for evaluating the in vitro chemosensitivity of CLL B-cells to multidrug regimen compounds. In the present study 40% of samples were resistant to CEOP regimen components in vitro. The possible role of MTT in predicting the clinical response to the CEOP regimen should still be established by prospective in vitro and in vivo studies.

Hybrid lymphoid blast crisis of chronic myeloid leukemia with both immunoglobulin and T-cell receptor gene rearrangements.

A case of Ph1+ chronic myeloid leukemia in blast crisis (CML-BC) is reported, in which the periodic acid Schiff and myeloperoxidase negative blasts displayed high terminal deoxynucleotidyl activity and coexpressed both B- (CD19, CD10, and CD24) and T- (CD7) lymphoid markers. In line with the immunophenotype, DNA analysis revealed a rearranged configuration of both the immunoglobulin and T-cell receptor (beta, gamma, and delta) genes. In spite of this dual B/T phenotype and genotype, the negativity of CyCD3 favors the suggestion that the target of the neoplastic event is an early B cell, with a cross lineage involvement of the putative common recombinase. However, taking into account that a normal counterpart of a biphenotypic B/T ALL has been recognized, it could be hypothesized that the leukemic transformation may have involved an oligopotent B/T lymphoid precursor. This case confirms the lineage heterogeneity of CML-BC and suggests that DNA analyses coupled to extensive immunophenotyping may allow further insight for a more precise recognition of both normal and leukemic ontogenesis.

Phenotypic and genotypic switch in Philadelphia-positive, BCR-positive blast crisis of chronic myeloid leukemia.

We report a case of Ph1-positive, bcr-positive chronic myeloid leukemia blast crisis (CML-BC) which at presentation showed a mixed myeloid/B-lymphoid immunophenotype along with TdT positivity and, at the molecular level, an oligoclonal rearrangement of the immunoglobulin heavy chain (IgH) gene region. After obtaining a successful remission, at the time of relapse the patient underwent a phenotypic and genotypic switch from mixed to myeloid phenotype, characterized by the loss of the lymphoid markers and TdT expression and by a germline configuration of the IgH gene region. The same bcr rearrangement was, however, found in both phases of the disease, supporting the suggestion of a true phenotypic and genotypic conversion. This report confirms that the neoplastic event in CML may take place at an early multipotent stem-cell level, prior to a well-defined phenotypic and genotypic lineage expression. Moreover, it is suggested that different factors (chemotherapy? growth factors?) may have either eradicated the bcr+/IgH+ clone and promoted the growth of bcr+/IgH- leukemic cells or, alternatively, supported the lymphoid differentiation program and induced a myeloid lineage shift.

Clinical significance of sIL2R, sCD23, sICAM-1, IL6 and sCD 14 serum levels in B-cell chronic lymphocytic leukemia.

BACKGROUND: The aim of the study was to establish the role exerted by some soluble factors in B-CLL disease mechanisms. MATERIALS AND METHODS: Serum levels of sIL2R, sCD23, sICAM-1, IL6 and sCD14 were detected in 47 B-CLL patients. Thirty-seven out of the 47 cases were in advanced/progressive stage, while the remaining 10 patients were defined as smouldering B-CLL. Twenty normal controls provided the reference values. Serum samples of 24 out 37 advanced/progressive cases were measured before and six months after the start of chemotherapy. RESULTS: The advanced/progressive patients showed significantly higher levels of sIL2R, sICAM-1 and sCD23 as compared to normal subjects. Furthermore, sIL2R, sICAM-1 and IL6 values were significantly higher in advanced/progressive B-CLL than in smouldering B-CLL patients. A statistically significant difference was found between smouldering B-CLL and controls for sCD14 only. sIL2R and sICAM-1 levels directly correlated with total tumor mass (TTM) score, sCD23 with both TTM score and lymphocytosis, and sCD14 with IgG serum values. sIL2R and sCD23 levels lowered significantly after chemotherapy, but only sCD23 and TTM variations after chemotherapy were closely correlated. CONCLUSIONS: sCD23 may be considered the only indicator of tumor mass, while the other soluble factors can be released through different mechanisms. In particular, sICAM-1 seems to correlate with the ability of the tumor to spread, while the sCD14 increase could indicate a role for this soluble factor in preventing infections in B-CLL patients.

In vitro sensitivity of chronic lymphocytic leukemia B-cells to fludarabine, 2-chlorodeoxyadenosine and chlorambucil: correlation with clinico-hematological and immunophenotypic features.

BACKGROUND: Chlorambucil (CLB), 2-chlorodeoxyadenosine (2-CDA) and fludarabine (FAMP) are among the most widely used drugs in chronic lymphocytic leukemia (CLL). Therefore we evaluated in vitro sensitivity to these drugs and cross-resistance of purine analogs. In addition, we correlated the in vitro data with the main clinico-hematological variables and surface markers. PATIENTS AND METHODS: Eighty CLL samples obtained from 63 untreated and 17 treated CLL patients were tested in vitro with the MTT assay. Lethal dose (LD)50 values were calculated to determine sensitivity to CLB, 2-CDA and FAMP. RESULTS: Samples were clustered either for a one-log increase of LD50 values or for LD50 threshold values of 3 microM for FAMP, 0.3 microM for 2-CDA and 7 microM for CLB, which correspond to the therapeutically achievable plasmatic levels of these drugs. A higher number of samples sensitive to 2-CDA were identified by the first approach; with the second method the relative order of sensitivity was FAMP > 2-CDA > CLB. Concerning 2-CDA and FAMP cross-resistance, out of 61 samples resistant to 2-CDA, 29.5% were sensitive to FAMP. Conversely, 13.9% out of 43 samples resistant to FAMP were sensitive to 2-CDA. No correlation was found between the main clinico-hematological features and the LD50 values of each drug either considering the whole series or only the untreated cases. In vitro drug sensitivity was also evaluated during the steady-state of the disease and at disease progression in six untreated cases. We observed a mean increase in the LD50 values of about 13, 38 and 22 times for CLB, FAMP and 2-CDA, respectively. Among the treated cases, the LD50 values of both purine analogs and CLB correlated with bone marrow histology. CLL cells expressing CD14, CD11c, CD11b, and FMC7 were more resistant in vitro to purine analogs but not to CLB. CONCLUSIONS: This study suggests that i) the purine analogs exert a greater cytotoxic effect on CLL cells; ii) 2-CDA and FAMP are not cross-resistant in vitro in a percentage of CLL samples, iii) a possible change in LD50 values may be related to modification of the disease status, and iv) the expression of certain surface markers, which are CLL-unrestricted, identifies samples with higher in vitro resistance to purine analogs.