Proliferation centers in chronic lymphocytic leukemia: correlation with cytogenetic and clinicobiological features in consecutive patients analyzed on tissue microarrays.

To better define the significance of proliferation centers (PCs), the morphological hallmark of chronic lymphocytic leukemia (CLL), lymph node biopsies taken from 183 patients were submitted to histopathologic and fluorescence in situ hybridization (FISH) studies using a 5-probe panel on tissue microarrays. Seventy-five cases (40.9%) with confluent PCs were classified as 'PCs-rich' and 108 cases (59.1%) with scattered PCs were classified as 'typical'. Complete FISH data were obtained in 101 cases (55.1%), 79 of which (78.2%) displayed at least one chromosomal aberration. The incidence of each aberration was: 13q- 36,7%, 14q32 translocations 30.8%, 11q- 24.7%, trisomy 12 19.5% and 17p- 15.6%. Five cases showed extra copies of the 14q32 region. The 'PCs-rich' group was associated with 17p-, 14q32/IgH translocation, +12, Ki-67>30%. The median survival from the time of tissue biopsy for PCs-rich and typical groups was 11 and 64 months, respectively (P=0.00001). The PCs-rich pattern was the only predictive factor of an inferior survival at multivariate analysis (P=0.022). These findings establish an association between cytogenetic profile and the amount of PC in CLL, and show that this histopathologic characteristic is of value for risk assessment in patients with clinically significant adenopathy.

A prospective survey of febrile events in hematological malignancies.

The Hema e-Chart prospectively collected data on febrile events (FEs) in hematological malignancy patients (HMs). The aim of the study was to assess the number, causes and outcome of HM-related FEs. Data were collected in a computerized registry that systematically approached the study and the evolution of FEs developing in a cohort of adult HMs who were admitted to 19 hematology departments in Italy from March 2007 to December 2008. A total of 869 FEs in 3,197 patients with newly diagnosed HMs were recorded. Fever of unidentified origin (FUO) was observed in 386 cases (44.4%). The other causes of FE were identified as noninfectious in 48 cases (5.5%) and infectious in 435 cases (50.1%). Bacteria were the most common cause of infectious FEs (301 cases), followed by fungi (95 cases), and viruses (7 cases). Mixed agents were isolated in 32 episodes. The attributable mortality rate was 6.7% (58 FEs). No deaths were observed in viral infection or in the noninfectious groups, while 25 deaths were due to FUO, 16 to bacterial infections, 14 to fungal infections, and three to mixed infections. The Hema e-Chart provided a complete system for the epidemiological study of infectious complications in HMs.

The role of high-dose therapy and autologous stem cell transplantation in patients with primary refractory Hodgkin's lymphoma: a report from the Gruppo Italiano per lo Studio dei Linfomi (GISL).

GISL recently conducted an exhaustive survey of 1078 patients with Hodgkin's Lymphoma (HL) enrolled between 1988 and 2002 in different prospective trials. Treatment failure was observed in 82 out of 1078 patients; of these 82 patients with refractory HL, complete information was available for 72, who form the evaluable population of the present study. After the initial therapy failure, 51 patients were treated with conventional salvage chemotherapy (CC) (n = 24) or high-dose chemotherapy (HDC) (n = 27); 4-year overall survival (OS) was 81% in the HDC group versus 38% in the CC group (P = 0.019). The remaining 21 patients had rapidly progressive disease and died. After a median follow-up of 2.8 years, the projected OS for all 72 patients is 58 and 49% at 3 and 5 years, respectively. Age <45 years, the absence of systemic symptoms and a PS <1 predicted a significantly longer OS. Interestingly, the majority of patients with two or three negative prognostic factors did not receive potentially curative therapy. In conclusion, HDC seems to be a reasonable option for selected patients with refractory HL, although the majority of them did not receive a transplant. Finally, patients with a high-risk score had little chance of receiving potentially curative treatment.

Peripheral blood CD38 expression predicts survival in B-cell chronic lymphocytic leukemia.

CD38 expression was investigated in 161 untreated patients with B-cell chronic lymphocytic leukemia (B-CLL). A score system, devised ad hoc by integrating the percentage and the mean fluorescence intensity (MFI) values of CD38(+) cells, indicated that B-CLL patients with a CD38 score < or =3 are characterized by a significantly longer survival compared to those with a CD38 score >3 (P=0.0026). Thirty-seven percent of patients with a CD38 score < or =3 and 58% of those with a score >3 were dead at 10 years. Multivariate analysis indicates that only the CD38 score successfully predicts survival (P=0.0028), with an estimated 3.8-fold greater risk of death for those cases with CD38 score >3.

Clinical activity and safety of combination immunotherapy with IFN-alpha 2a and Rituximab in patients with relapsed low grade non-Hodgkin's lymphoma.

BACKGROUND AND OBJECTIVES: To determine the clinical activity and safety of the combination immunotherapy of the chimeric anti-CD20 antibody, Rituximab, and Interferon (IFN)- alpha 2a DESIGN AND METHODS: Sixty-four patients with relapsed low-grade or follicular B-cell non Hodgkin's lymphoma received 4 infusion of Rituximab (375 mg/m(2) x dose) after priming and simultaneous treatment with IFN- alpha 2a. RESULTS: The overall response rate was 70% with 33% complete responses. Median for duration of response is 19 months, after a median follow-up of 22 months. By univariate analysis none of the most common prognostic factors predicted for response to therapy. After treatment 10 patients become bcl-2 negative in the bone marrow, but no correlation between molecular and clinical response was found. Fifty-three patients (83%) had drug related or unknown origin adverse events. The number of adverse events per patient varied from 1 to 21. Considering all 272 events, 231 (85%) were grade 1 or 2, 36 (13%) grade 3 and 5 (2%) grade 4. Twenty-three patients required reduction in the dose and/or short discontinuation of IFN treatment, either during priming or subsequent treatment. The most frequent adverse events were leukopenia, fever, neutropenia, hypotension and thrombocytopenia. INTERPRETATION AND CONCLUSIONS: this report shows that combination immunotherapy Rituximab + IFN- alpha 2a is active and relatively well tolerated. The overall response rate of 70% and the median duration remission of 19 months compare favorable with the results obtained with Rituximab alone in similar subset of patients. Randomized trials, investigating Rituximab versus combination immunotherapy are needed.

Clinical tumor cell distribution pattern is a prognostically relevant parameter in patients with B-cell chronic lymphocytic leukemia.

BACKGROUND AND OBJECTIVES: B-cell chronic lymphocytic leukemia (B-CLL) cells are variably distributed among the major lymphoid compartments contributing to the heterogeneous clinical presentation and course of this disease. In order to evaluate this variable distribution we propose a model for its clinical assessment. DESIGN AND METHODS: We introduce the model for tumor distribution (TD) assessment based on TTM scoring system, where TD value represents percentage of total tumor mass infiltrating peripheral blood and bone marrow (TD=TM(1)/TTM). TD in B-CLL can be categorized into 3 subgroups: pure leukemia if TD=100%, predominantly leukemia if TD=50-99% and predominantly lymphoma TD<50%. RESULTS: Among 341 B-CLL patients there were 22.6%, 55.1%, 22.3%, pure leukemia, predominantly leukemia and predominantly lymphoma cases, respectively. TD parameter was strongly associated in univariate analysis with TTM size, Rai and Binet stages, spleen size and beta(2) microglobulin. TD was associated with response to therapy and survival, with higher TD values translated into higher response rates and longer survival. However, in univariate and multivariate Cox analysis TD displayed much stronger relationship with prognosis in female patients, where it is the strongest independent predictor of survival along with age and Binet stage. INTERPRETATION AND CONCLUSIONS: TD, a quantitative and simple clinical parameter, easily assessed in all patients, offers a reliable tool for evaluation of tumor cell distribution in B-CLL. It has independent and strong prognostic power in females, as opposed to males, possibly unmasking important, yet unrecognized, biological difference in B-CLL patients.

Validation of the international prognostic index in working formulation group A low-grade non-Hodgkin's lymphoma: retrospective analysis of 137 patients from the Gruppo Italiano per lo Studio dei Linfomi registry.

BACKGROUND AND OBJECTIVE: The subset of non-follicular non-Hodgkin's lymphoma (NHL) includes patients with varied prognoses, thus suitable for different therapeutic approaches. The International Prognostic Index (IPI), originally proposed for aggressive NHL, has been demonstrated to be of prognostic relevance also in follicular NHL. The main aim of the study was to validate the IPI in this histologic category; in addition, the specific prognostic classification, currently employed in the Gruppo Italiano per lo Studio dei Linfomi (GISL) prospective therapeutic trials and based on different features, more similar to those applied to chronic lymphocytic leukemia, was analyzed. DESIGN AND METHODS: The present series consists of 137 evaluable patients affected by Working Formulation group A NHL out of 256 cases referred to the GISL Registry. The retrospective prognostic study included the evaluation by both univariate and multivariate analyses of overall survival, response to therapy and response duration. The IPI was applied as originally proposed. The GISL definition of indolent and aggressive disease at diagnosis was based on the presence of B symptoms, bulky disease, anemia and thrombocytopenia. RESULTS: The distribution of patients in IPI risk groups was rather unbalanced with 18%, 47%, 28% and 7% of cases classified as low (L), intermediate-low (IL), intermediate-high (IH) and high (H) risk, respectively. The median overall survival was not reached in either L or IL risk groups, and was 84.1 and 7.4 months for IH and H risk groups, respectively (p=0. 0005). A simplified IPI model was designed merging patients in both intermediate risk groups and the statistical difference of survival retained its significance. GISL prognostic stratification was demonstrated to have a significant association with survival, with a median survival of 71.3 months in aggressive disease and a median survival not reached at 152 months in indolent disease. Both the simplified IPI model and the GISL risk definition retained their significance in multivariate analysis for overall survival, while for response to therapy only the simplified IPI model resulted to be of statistical significance. In addition, the GISL prognostic stratification identified patients with different outcomes within the IPI intermediate risk group, with a median survival of 70.2 months for patients with aggressive disease wheras the median survival for those with indolent disease was not reached. Finally, a prognostic score resulting from the integration of the simplified IPI and the GISL system was statistically validated. INTERPRETATION AND CONCLUSIONS: The retrospective analysis of this series demonstrates the validity of the IPI in non-follicular indolent NHL and the usefulness of integrating the IPI parameters with disease specific prognostic variables.

Prognosis of follicular lymphoma: a predictive model based on a retrospective analysis of 987 cases. Intergruppo Italiano Linfomi.

Patients (n-987) with a histologically confirmed diagnosis of follicular lymphoma were studied with the aim of developing a prognostic model specifically devised for this type of lymphoma. We collected information on age, sex, Ann Arbor stage, number of extranodal disease sites, bone marrow (BM) involvement, bulky disease, B symptom criteria (fever, night sweats, and weight loss), performance status (PS), serum lactate dehydrogenase (LDH) level, serum albumin level, hemoglobin level, and erythrocyte sedimentation rate (ESR). In the training sample of 429 patients with complete data, multivariate analysis showed that age, sex, number of extranodal sites, B symptoms, serum LDH level, and ESR were factors predictive for overall survival. Using these 6 variables, a prognostic model was devised to identify 3 groups at different risk. The 5- and 10-year survival rate was 90% and 65% for patients at low risk, respectively; 75% and 54% for patients at intermediate risk; and 38% and 11% for those at high risk (log-rank test, 86.62; P <. 0001). The model was also predictive (P =.0001) in the validation sample of 265 patients with complete data only for the 6 variables used in the development of the model and even in the group of 210 patients from the validation sample uniformly treated with doxorubicin-containing regimens (P =.0001). The prognostic model appears to be very useful in identifying patients with follicular lymphoma at low, intermediate, or high risk.

Surface CD14 positivity in B-cell chronic lymphocytic leukaemia is related to clinical outcome.

The aberrant expression of the myelomonocytic antigen CD14 was investigated in 128 untreated patients diagnosed with B-cell chronic lymphocytic leukaemia (B-CLL). A cut-off value of 5 x 10(9)/l CD14-positive cells was chosen for statistical analysis because it showed the best discriminating power among patients with different clinical features. 56 cases had a CD14+ cell count >5 x 10(9)/l. A significant correlation was found between Rai and Binet stages and total tumour mass (TTM) score on one hand, and the absolute CD14+ cell cut-off, on the other. This relationship was more evident in Rai 0-II and Binet A-B stages, where a CD14+ cell count >5 x 10(9)/l was preferentially distributed among patients with a higher tumoral mass. In univariate analysis the survival probability at 5 and 10 years showed a significant correlation with Rai and Binet stages, TTM score, CD14+ absolute cell count and median age. The median overall survival (OS) was 63 months for patients with a CD14+ cell count >5 x 10(9)/l and 136 months for those with a CD14+ cell count < 5 x 10(9)/l. In the multivariate Cox regression model, Rai stage, age and CD14+ cell count were independent significant factors for the prediction of OS. Finally, when the same analysis was restricted to Rai stages 0-II, CD14+ cell count was the only significant independent parameter influencing OS, with a relative death risk of 3.8. In conclusion, these data reveal that CD14+ represents an important marker for predicting OS in B-CLL patients and, therefore, we suggest that it should be included in the immunological characterization of B-CLL.

Fludarabine treatment in B-cell chronic lymphocytic leukemia: response, toxicity and survival analysis in 47 cases.

BACKGROUND AND OBJECTIVE: Fludarabine monophosphate (FAMP) is a purine analog with specific therapeutic activity in B-cell chronic lymphocytic leukemia (CLL). Its current use as front-line therapy of CLL is still a matter of debate both because of the controversial results of the clinical trials so far reported and because of the toxicity profile of the drug. In order to contribute to clarifying the possible role of FAMP, we report a retrospective analysis of the results obtained with the purine analog in CLL patients in different phases of the disease. DESIGN AND METHODS: Forty-seven patients affected by advanced CLL, 36% untreated, 31.9% relapsed and 31.9% resistant, were treated with FAMP 25 mg/m2/day, either for 4 days every 3 weeks in 29 cases, or for 5 days every 4 weeks in 18. The median number of FAMP cycles was 6 (range 2-11). Response was defined according to total tumor mass (TTM) score reduction and toxicity was expressed according to WHO grading criteria. The median follow-up of the series was 13 months from the beginning of FAMP therapy. RESULTS: Out of 47 evaluable patients the response rate was 74.4%, with 34% complete response (CR). The overall response rate was 94%, 80% and 46.6% in untreated, relapsed and resistant cases, respectively; a significantly higher number of responses was associated with no previous treatment and number of FAMP cycles. Fifty-three percent of all cases and 58.8% of untreated ones did not experience any toxicity. Treatment-related side effects were mainly autoimmune phenomena in untreated patients and infectious complications in treated ones. One heavily pre-treated patient died because of neurologic complications. Median time to re-treatment was18 months (range 1-30) and was influenced by age and previous treatment. The overall median survival was 35.7 months with a significantly higher proportion of surviving cases among RAI 0-II stages, responders and patients receiving more than 5 FAMP cycles. INTERPRETATION AND CONCLUSIONS: The present report confirms the high efficacy of FAMP in previously pre-treated cases with acceptable toxicity and encourages its use as front-line treatment provided that the results of randomized trials demonstrate its superiority over conventional chemotherapy. The possible development of autoimmune phenomena should, however, be considered seriously.

Retrospective analysis of mantle cell lymphoma: experience of the "Gruppo Italiano per lo Studio dei Linfomi" (GISL).

BACKGROUND AND OBJECTIVE: Mantle cell lymphoma is a recently recognized histologic entity with specific biological and clinical features. Clinically, the reported unfavorable outcome of these patients has focused attention on this category of non-Hodgkin's lymphoma (NHL). DESIGN AND METHODS: The slide specimens of 69 NHL patients, originally classified as Working Formulation (WF) group B and E, were reviewed. The clinical features at presentation, response to therapy, response duration and survival were analyzed in cases reclassified as MCL. The correlation between clinical and histologic characteristics and the final outcome was evaluated. RESULTS: Out of 69 cases, 34 specimens were reclassified as MCL; in 6 patients, previously classified as WF group B, the nodular pattern was confirmed; in 2 instances the blastoid form was recognized. After a median follow-up of 35.7 months, the entire series displayed a median overall survival of 41.2 months; a significantly longer survival was associated with the nodular histologic pattern, IPI score < 2, response achievement, and a higher Hb level. The vast majority of patients received anthracycline-containing combination chemotherapy. Complete remission rate was 38.8% and overall response rate was 67.6%; response achievement was significantly influenced only by Hb level. Median response duration was 23.3 months. INTERPRETATION AND CONCLUSIONS: The present study confirms the unfavorable clinical course of MCL and the possible need for an alternative therapeutic strategy for this NHL category. Therefore, the correct identification of MCL at diagnosis appears of relevance.

Efficacy of two different ProMACE-CytaBOM derived regimens in advanced aggressive non-Hodgkin's lymphoma. Final report of a multicenter trial conducted by GISL.

BACKGROUND AND OBJECTIVE: To compare the efficacy of ProME(Epidoxorubicin)CE-CytaBOM (PE-C) and ProMI(Idarubicin)CE-CytaBOM (PI-C) in the treatment of adult patients with aggressive non Hodgkin's lymphoma in a multicenter randomized controlled trial performed by 18 centers of the Italian Lymphoma Study Group (GISL). DESIGN AND METHODS: One hundred and twenty-eight and 122 patients were randomly assigned to receive either 6 courses of PE-C or PI-C, respectively. Some patients achieving complete remission with induction therapy participated in another randomized study comparing no further therapy versus maintenance therapy consisting of four blocks of two drugs. RESULTS: The rate of CRs was 62% and 64% for patients treated with PE-C and PI-C, respectively (p = 0.51). The 5-year relapse-free survival was 60% for PE-C and 53% for PI-C (p = 0.29). The estimated relapse-free disease survival rates at 4 years were 75% for patients in the consolidation group and 57% for those in the observation group (p = 0.11). Patients alive in first complete remission 4 years after study entry were estimated to be 39% in the PE-C arm and 38% in the PI-C arm (p = 0.90). The 3-year and 5-year estimated survival rates were 61% and 55% for the PE-C group and 56% and 47% for the PI-C group (p = 0.26). Fatal toxicities occurred in 7 patients (2.9%) with active disease and in 4 patients (1.7%) in complete remission. Stage (p = 0.04), bulky disease (p = 0.02), serum LDH (p = 0.0006), serum albumin (p = 0.0051), hemoglobin (p = 0.0011), performance status (p = 0.0001), International prognostic index (p < 0.0001) and the index proposed by the French group G.E.L.A. (p < 0.0001) were of prognostic value. In a multivariate analysis (Cox regression model) alternatively IPI alone or G.E.L.A. index plus performance status emerged as independent prognostic factors. INTERPRETATION AND CONCLUSIONS: The present study indicates that epirubicin and idarubicin in a combined chemotherapy regimen, have similar activities. The toxic profile also indicates the safety of both anthracyclines at the dosages employed, suggesting their possible dose escalation in a combined chemotherapy setting. PE-C and PI-C were both effective and feasible regimens in an outpatient setting, with acceptable cardiovascular toxicity. The trend toward a better outcome in patients undergoing consolidation therapy after the achievement of a complete remission, warrants further investigation.

In vitro drug-induced cytotoxicity predicts clinical response to fludarabine in B-cell chronic lymphocytic leukaemia.

We investigated the possible value of an in vitro drug-induced cytotoxicity assay in predicting clinical response to fludarabine (FAMP) in chronic lymphocytic leukaemia (CLL). The median FAMP-LD50 values for cases designated as complete response (CR), partial response (PR), no response (NR) and progressive disease (PD) were 1.43, 2.05, 24.8 and 77.9 microg/ml, respectively (P=0.013). A significant lower mean FAMP-LD50 value was observed in the in vivo responding cases as compared to non-responding ones (3.0 +/- 0.82 SEM v 42.3 +/- 12.6 SEM, P=0.001). Only FAMP-LD50 < or = 2.5 microg/ml and more than four FAMP courses significantly influenced the response rate in univariate and multivariate analyses. The MTT assay may be of value in predicting clinical response to FAMP in CLL patients.

High dose chlorambucil versus Binet's modified cyclophosphamide, doxorubicin, vincristine, and prednisone regimen in the treatment of patients with advanced B-cell chronic lymphocytic leukemia. Results of an international multicenter randomized trial. International Society for Chemo-Immunotherapy, Vienna.

BACKGROUND: In recent years, much attention has been paid to the possible efficacy of intensive chemotherapy in the treatment of advanced, progressive B-cell chronic lymphocytic leukemia (CLL) patients. For this reason, the International Society for Chemo-Immunotherapy, Chronic Lymphocytic Leukemia Cooperative Group, has begun a randomized multicenter trial comparing Binet's modified cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen with continuous high dose chlorambucil (HD-CLB). METHODS: During the period January 1987 to May 1993, 228 previously untreated CLL patients from 7 cooperative institutions were randomized to this trial. Advanced and/or progressive disease was defined by high Total Tumor Mass (TTM) score (> 9), and/or short doubling time (DT) (< 12 months), and/or bone marrow failure. The response to therapy was defined by reduction of the initial TTM score. The end points of the trial were response rate, survival, and toxicity. RESULTS: HD-CLB resulted in a higher response rate than CHOP in evaluable cases, with 89.5% overall responses (complete response+partial response) versus 75%, respectively (P < 0.001). At the time of an analysis performed in July 1995 (after a median follow-up period of 37 months), overall survival was also longer in the HD-CLB treatment arm (median survival, 68 months) than in the CHOP treatment arm (median survival, 47 months) (P < 0.005). Toxicity was acceptable and comparable in the two treatment arms. CONCLUSIONS: The current study showed that HD-CLB is an effective and well-tolerated therapeutic option for patients with advanced and/or progressive CLL. Therefore, the authors recommend its wider use, possibly in comparison with and/ or in combination with new therapeutic agents, such as purine analogues.

In vitro improvement of chlorambucil-induced cytotoxicity by deflazacort and 6-methylprednisolone in B-cell chronic lymphocytic leukaemia.

We examined whether CLL cell chemosensitivity to in vitro exposure to chlorambucil (CLB) might be improved by the presence of deflazacort (DFZ) in comparison to 6-methylprednisolone (PDN). The PDN lethal dose (LD)50 values were low in 5 samples, intermediate in 4 and high in 7. Low, intermediate and high DFZ-LD50 values were detected in 3, 2 and 11 samples, respectively. The CBL-LD50 mean values were significantly reduced at all PDN and at the 4 highest DFZ concentrations. However, a dose-response effect was seen only in the DFZ group. Both CLB-DFZ and CLB-PDN interactions were analysed in 16 samples at 25 different dose-combinations, resulting in 400 comparisons between expected and observed leukaemic cell survival (LCS) values for each group. In particular, 45.75% and 40% dose combinations were synergistic in CLB-DFZ and CLB-PDN groups, respectively. A relatively higher number of antagonistic interactions were observed among CLB-PDN dose combinations, while analogous number of additive interactions were detected. At concentrations of CLB x1 microgram/ml the phenomenon of synergism, regardless of the steroid concentration, did occur more frequently. On the other hand, a more elevated number of antagonistic interactions were counted at CLB 100 micrograms/ ml. In conclusion, both DFZ and PDN synergize in vitro with CLB, especially at low concentrations of the alkylating agent.

Long-term clinical outcome of B-cell chronic lymphocytic leukaemia patients in clinical remission phase evaluated at phenotypic level.

This retrospective study aimed to evaluate the long-term prognostic impact of phenotypic remission in B-cell chronic lymphocytic leukaemia (CLL) patients who have achieved clinical, haematological and bone-marrow complete remission (CR) after conventional chemotherapy. The clinical and phenotypic data of 77 CLL patients in CR with a median follow-up from CR achievement of 54 months (range 5-127) were analysed. 32 patients (42%) displayed a normalized phenotype as evaluated by k:lambda ratio or by CD5+/CD19+ cell numbers. Patients with normalized phenotype demonstrated a significantly higher incidence of female sex, a lower relapse rate, a trend for higher prevalence of stage A and a lower occurrence of CLL-related deaths. The relapse-free survival of patients with normalized phenotype was significantly longer (P = 0.02), whereas no difference in overall survival was found between the two groups. Interestingly, Binet's stage at diagnosis was highly predictive of the overall survival following CR achievement. From the results of the present study we conclude that a phenotype normalization at CR obtained with conventional chemotherapy indicates a higher probability of a longer CR but it does not translate into prolonged survival. Clinical features at diagnosis, such as stage distribution, are apparently stronger predictors of the final outcome. These results emphasize, however, the need for a routine assessment of the quality of response since this information could be crucial in designing therapeutic strategies for young patients suffering from advanced CLL.

Bcl-2 protein expression and p53 gene mutation in chronic lymphocytic leukemia: correlation with in vitro sensitivity to chlorambucil and purine analogs.

BACKGROUND AND OBJECTIVE: Bcl-2 oncogenic protein expression plays a major role in blocking the apoptotic mechanism. p53 gene mutations have also been suggested to account for the chlorambucil resistance in CLL. Thus we studied the relationship between bcl-2 protein expression, p53 gene mutations and in vitro drug sensitivity in CLL. METHODS: Fifty-three samples from untreated CLL patients in early disease stages were tested in vitro for chemosensitivity to chlorambucil (CLB), fludarabine (FAMP) and 2-chlorodeoxyadenosine (2-CDA) using the MTT assay. Intracellular bcl-2 protein expression was evaluated by flow cytometry analysis. p53 gene mutations were detected by using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis. RESULTS: The median LD50 values were 1.55 microM, 4.41 microM and 58.2 microM for 2-CDA, FAMP and CLB, respectively. About 23%, 41% and 11% of samples were defined as being sensitive to FAMP, 2-CDA and CLB, respectively, when samples were clustered for LD50 threshold values corresponding to the plasmatic levels of the drug. No statistically significant difference in bcl-2 protein expression was noted between sensitive and resistant samples for each drug. A p53 gene mutation was detected in 4 of the 30 cases studies and all of them were among samples resistant to CLB. INTERPRETATION AND CONCLUSIONS: Bcl-2 expression is not an indicator of in vitro response to drugs in CLL; similarly, although the four cases showing a p53 gene mutation were associated with CLB resistance, drug resistant samples were also observed in the group of patients showing wild type p53, suggesting multiple mechanisms of drug resistance in CLL.