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

Chlorambucil plus Rituximab as Front-Line Therapy in Elderly/Unfit Patients Affected by B-Cell Chronic Lymphocytic Leukemia: Results of a Single-Centre Experience

The current standard first line therapy for fit patients with B-CLL/SLL is based on combination of fludarabine-cyclophosphamide and rituximab. However, elderly patients or patients with comorbidities poorly tolerate purine analogue-based chemotherapy and they are often treated with Chlorambucil (Chl) only. However, complete response (CR) and overall response (OR) rates with Chl are relatively low. We now investigated whether the addition of Rituximab to Chl will improve the efficacy without impairing the tolerability in elderly and unfit patients. We included in our study 27 elderly or unfit patients that had not received prior therapy. All patients were treated with Chl (1mg/Kg per 28-day cycle for 8 cycles) plus Rituximab (375 mg/m² for the first course and 500 mg/m² for subsequent cycles until the 6^th cycle). We obtained an OR rate of 74%. The most frequent adverse effect was grade 3–4 neutropenia, which occurred in 18.5% of the patients. Infections or grade 3–4 extra-hematological side effects were not recorded. None of the patients required reduction of dose, delay of therapy or hospitalization. Overall, these data suggest that Chl-R is an effective and well tolerated regimen in elderly/unfit patients with CLL.

Translocation of nucleoside analogs across the plasma membrane in hematologic malignancies

Nucleoside analogs are currently used in the treatment of various hematologic malignancies due to their ability to induce apoptosis of lymphoid cells. For nucleoside-derived drugs to exert their action, they must enter cells via nucleoside transporters from two gene families, SLC28 and SLC29 (CNT and ENT, respectively). Once inside the cell, these drugs must be phosphorylated to their active forms. In contrast, some members of the ATP-binding cassette (ABC) protein family have been identified as responsible for the efflux of the phosphorylated forms of these nucleoside-derived drugs. Here, we review the main nucleoside analogs used in hematologic malignancies and focus especially on those that are currently used in chronic lymphocytic leukemia (CLL). Moreover, we discuss the pharmacological profile of the nucleoside transporters, which determines the bioavailability of and cell sensitivity to these nucleoside-derived drugs. We also discuss the expression of nucleoside transporters and their activities in CLL as well as the possibility of modulating these transporter activities as a means of modulating intracellular drug availability and, consequently, responsiveness to therapy.

Enhancement of fludarabine sensitivity by all-trans-retinoic acid in chronic lymphocytic leukemia cells

BACKGROUND

A subset of patients with fludarabine-resistant chronic lymphocytic leukemia has previously been shown to express elevated intracellular levels of the concentrative high-affinity fludarabine transporter hCNT3, without any detectable related activity. We have recently shown that all-trans-retinoic acid is capable of inducing hCNT3 trafficking to plasma membrane in the MEC1 cell line. We, therefore, evaluated the effect of all-trans-retinoic acid on hCNT3 in primary chronic lymphocytic leukemia cells as a suitable mechanism to improve fludarabine-based therapy of chronic lymphocytic leukemia.

DESIGN AND METHODS

Cells from 23 chronic lymphocytic leukemia patients wild-type for P53 were analyzed for ex vivo sensitivity to fludarabine. hCNT3 activity in chronic lymphocytic leukemia cell samples was evaluated by measuring the uptake of [8-(3)H]-fludarabine. The amounts of transforming growth factor-β1 and hCNT3 messenger RNA were analyzed by real-time polymerase chain reaction. The effect of all-trans-retinoic acid on hCNT3 subcellular localization was analyzed by confocal microscopy and its effect on fludarabine-induced apoptosis was evaluated by flow cytometry analysis using annexin V staining.

RESULTS

Chronic lymphocytic leukemia cases showing higher ex vivo basal sensitivity to fludarabine also had a greater basal hCNT3-associated fludarabine uptake capacity compared to the subset of patients showing ex vivo resistance to the drug. hCNT3 transporter activity in chronic lymphocytic leukemia cells from the latter patients was either negligible or absent. Treatment of the fludarabine-resistant subset of chronic lymphocytic leukemia cells with all-trans-retinoic acid induced increased fludarabine transport via hCNT3 which was associated with a significant increase in fludarabine sensitivity.

CONCLUSIONS

Improvement of ex vivo fludarabine sensitivity in chronic lymphocytic leukemia cells is associated with increased hCNT3 activity after all-trans-retinoic acid treatment.

Comprehensive assessment of prognostic factors predicting outcome in Chinese patients with chronic lymphocytic leukemia treated with fludarabine and cyclophosphamide

To determine whether prognostic factors remain relevant to chronic lymphocytic leukemia (CLL) patients treated with fludarabine and cyclophosphamide (FC), we prospectively evaluated 86 Chinese CLL patients who received FC in first-line therapy. Twenty-four patients (27.9%) achieved complete remission (CR), and overall response rate was 75.6%. With a median follow-up of 41 months, the median progression-free survival (PFS) was 36.0 months and median overall survival (OS) has not been reached. The strong correlations of lower CR rate with advanced Binet stage, unmutated IGHV, cytogenetic abnormalities of del(17p13) or del(11q23), and p53 mutations were observed by univariable analyses. Stepwise logistic regression identified that unmutated IGHV and p53 abnormality (p53 deletion or mutation) were associated with a decreased odds of achieving CR. The less cycles of treatment, not achieving CR, advanced Binet stage, and p53 abnormality significantly correlated with a shortened PFS. Furthermore, in a multivariate analysis, p53 abnormality and advanced Binet stage were identified as being significant risk factors for early relapse. Not achieving CR, advanced Binet stage, ZAP-70-positive, and p53 abnormality were the adverse factors in determining OS. Only p53 aberration was independently associated with significantly shorter OS by a multivariate analysis. These results suggest that patients with p53 abnormality should be considered for alternative therapies.

A comparison of the efficacy and safety of oral and intravenous fludarabine in chronic lymphocytic leukemia in the LRF CLL4 trial

BACKGROUND

An oral formulation of fludarabine was introduced for use in chronic lymphocytic leukemia in 2001 following studies demonstrating the bioequivalence of a 40 mg/m(2) oral dose with a 25 mg/m(2) intravenous dose. We assessed retrospectively the efficacy of these two routes of administration in the LRF CLL4 trial.

METHODS

A total of 777 patients were randomized from 1999-2004 to receive fludarabine, alone or with cyclophosphamide, or chlorambucil. In 2001, a protocol amendment allowed the oral formulation. There were 117 assessable patients who received fludarabine intravenously and 252 who received it orally. A total of 387 patients given chlorambucil acted as a control group.

RESULTS

Patients given oral fludarabine were less likely to receive the full dose (P = .0004) and experienced more, predominantly gastrointestinal, toxicity. Progression-free survival (PFS) and overall survival were not affected by the route of administration (PFS hazard ratio, 1.10; 95% confidence interval, 0.87-1.40), but the overall rate of response to treatment appeared to be lower with the oral formulation (P = .003). However, patients recruited since 2001 were older (P = .03) and were more likely to have TP53 deletion, and response rates after 2001 were also lower in the chlorambucil group. After excluding patients with TP53 deletion, no significant difference in outcome was attributable to the route of administration.

CONCLUSIONS

Although the LRF CLL4 data suggest no important difference in the effectiveness of oral compared with intravenous fludarabine, randomized trials are needed to reliably evaluate this comparison, particularly in combination with rituximab. Meanwhile, it is important to monitor compliance and gastrointestinal side effects with the oral route and to switch to intravenous therapy if a reduced dose is being received.

Development of fludarabine formulations in the treatment of chronic lymphocytic leukemia

Fludarabine is an antineoplastic agent used in the treatment of hematological malignancies, particularly chronic lymphocytic leukemia (CLL) and indolent B-cell lymphoma. Because of its immunosuppressive effects, fludarabine has been added to reduced intensity conditioning regimens. The oral formulation of fludarabine has become widely available. Pharmacokinetic studies have shown that an oral dose of 40 mg/m²/d would provide systemic drug exposure similar to the standard intravenous (IV) dose of 25 mg/m²/d. The oral dose can be taken once daily without any dietary restrictions. Dose adjustments are mandatory in patients with renal impairment to avoid increased toxicity. Several noncomparative trials in previously untreated and treated patients with CLL have shown that treatment with the oral formulation demonstrates similar efficacy compared to historical control groups treated with the IV formulation. The tolerability profile of oral fludarabine seems similar to that of the IV formulation. Myelosuppression and infectious complications are the most frequently reported adverse events. Gastrointestinal toxicity is more frequent with the oral formulation, but is usually of mild or moderate severity. Although oral fludarabine makes treatment more convenient, health care workers must be aware of the compliance behavior of each patient.

Fludarabine in the treatment of chronic lymphocytic leukemia: a review

Fludarabine (FAMP) is the most effective and most extensively studied purine analog in indolent B-cell malignancies. Its use is indicated for first-and second-line treatment of B-cell chronic lymphocytic leukemia (B-CLL). FAMP as a single agent has produced superior response rates and progression-free survival than standard therapy with chlorambucil and alkylator-based regimen. Efficacy of FAMP may be increased by combining this purine analog with other chemotherapeutic and non-chemotherapeutic agents. FAMP and cyclophosphamide combination (FC) has shown promising results with higher overall response and complete response rates than FAMP in monotherapy, although no difference has been detected in survival. Quality of response and eradication of minimal residual disease (MRD) have been reported to be associated with prolonged survival. Eradication of MRD has been achieved by combining FC with mitoxantrone or monoclonal antibody including alemtuzumab or rituximab or both. FAMP has been widely used in non-myeloablative conditioning regimens, often combined with a variety of other cytotoxic agents, with the aim of inducing enough immunosuppression to allow successful engraftment and to exert some pretransplant anti-tumor activity. The current paper provides an overview of use of FAMP as a single agent or as a cornerstone of different therapeutic strategies for treatment of B-CLL patients.

Predicting clinical outcome in CLL: how and why

The clinical course of patients with chronic lymphocytic leukemia (CLL) is heterogeneous, with some patients experiencing rapid disease progression and others living for decades without requiring treatment. Clinical features and molecular/biologic factors such as ZAP-70, immunoglobulin heavy chain (IGHV) gene mutation status, and cytogenetic abnormalities on fluorescent in situ hybridization (FISH) have been found to be robust predictors of treatment-free survival and overall survival among newly diagnosed patients. Beyond their widely recognized value for providing insight into disease biology and utility for stratifying patient risk in clinical trials, these prognostic tools play an important role in the current counseling and management of patients with CLL. Recent studies have focused on how to combine the results of multiple prognostic assays into an integrated risk stratification system and explored how these characteristics influence response to treatment. This chapter reviews the available tools to stratify patient risk and discusses how these tools can be used in routine clinical practice to individualize patient counseling, guide the frequency of follow-up, and inform treatment selection.