The role of stem cell transplantation in chronic lymphocytic leukemia

Comparison of Different Stem Cell Mobilization Regimens in AL Amyloidosis Patients

High-dose melphalan (HDM) and autologous blood stem cell transplantation (ABSCT) is an effective treatment for transplantation-eligible patients with systemic light chain (AL) amyloidosis. Whereas most centers use granulocyte colony-stimulating factor (G-CSF) alone for mobilization of peripheral blood stem cells (PBSC), the application of mobilization chemotherapy might offer specific advantages. We retrospectively analyzed 110 patients with AL amyloidosis who underwent PBSC collection. Major eligibility criteria included age <70 years and cardiac insufficiency New York Heart Association ≤III°. Before mobilization, 67 patients (61%) had been pretreated with induction therapy, including 17 (15%) patients who had received melphalan. Chemo-mobilization was performed with either cyclophosphamide, doxorubicin, dexamethasone (CAD)/G-CSF (n = 78, 71%); ifosfamide/G-CSF (n = 14, 13%); or other regimens (n = 8, 7%). AL amyloidosis patients with predominant heart involvement and/or status post heart transplantation were mobilized with G-CSF only (n = 10, 9%). PBSC collection was successful in 101 patients (92%) at first attempt. The median number of CD34⁺ cells was 8.7 (range, 2.1 to 45.5) × 10⁶ CD34⁺/kg collected in a median of 1 leukapheresis (LP) session. Compared with G-CSF-only mobilization, a chemo-mobilization with CAD/G-CSF or ifosfamide/G-CSF had a positive impact on the number of collected CD34⁺ cell number/kg per LP (P <.001, multivariate). Melphalan-containing previous therapy and higher age had a significant negative impact on quantity of collected CD34⁺ cells. Median common toxicity criteria (CTC) grade of nonhematologic toxicity was II (range, 0 to IV). Life-threatening CTC grade IV adverse events were observed in 3 patients with no fatalities. Cardiovascular events were observed in 17 patients (22%) upon CAD/G-CSF mobilization (median CTC: grade 3; range, 1 to 4). Toxicity in patients undergoing ifosfamide/G-CSF mobilization was higher than in with those who received G-CSF-only mobilization. HDM and ABSCT were performed in 100 patients. Compared with >6.5 × 10⁶ transplanted CD34⁺ cells/kg, an ABSCT with <3 × 10⁶ CD34⁺ cells/kg was associated with a longer duration to leukocyte reconstitution >1 × 10⁹/L and a reduced platelet count <150 × 10⁹/L 1 year after ASCT. Our results show that CAD chemotherapy is very effective in PBSC mobilization and has a tolerable toxicity profile in AL amyloidosis patients. A further toxicity reduction by omission of doxorubicin might be considered. Because of advanced nonhematologic toxicity, ifosfamide administration cannot be recommended. However, G-CSF mobilization alone is also safe and effective. Considering the hematopoietic reconstitution and long-term stem cell function, our results provide a rationale to collect and transplant as many as >6.5 × 10⁶ CD34⁺ cells/kg, if feasible with reasonable effort.

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

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

Reduced-Intensity Stem Cell Transplantation

The recognition that the immune system can play a major role in the control and cure of transplantable disorders led to the development of reduced-intensity allogeneic transplantation. The notion is that a compromise can be made between the intensity of conditioning and the fostering of graft-versus-host disease/ graft-versus-leukemia (GVHD/GVL), allowing the use of less intense conditioning with concomitantly less intense immediate toxicity. Reduced-intensity conditioning regimens have allowed the application of transplantation to older patients and to patients with underlying medical problems that preclude full-dose transplantation. Clearly, in some settings in which dose intensity is important, reduced-intensity regimens are less useful. However, for diseases that are either indolent, highly susceptible to GVL, or under good control before entering transplantation, this approach appears to have substantial benefits. Although the therapy appears to be valuable, concerns about delayed immune reconstitution and GVHD remain.

New agents in chronic lymphocytic leukemia

For many years, alkylating agents, especially chlorambucil, have been considered the drugs of choice for first-line treatment of progressive and symptomatic chronic lymphocytic leukemia (CLL). More recently, treatment approaches have included purine nucleoside analogs (PNAs), fludarabine or cladribine (2-CdA), and monoclonal antibodies (MoAbs). PNAs are highly active in patients with CLL, previously treated and untreated. Significantly higher overall response and complete response in patients treated initially with fludarabine or 2-CdA than in those treated with chlorambucil- or cyclophosphamide-based combination regimens have been recently confirmed in prospective, randomized trials. However, the median survival times do not differ among the patients treated with PNA and alkylating agents. The MoAbs directed against CD52 antigen (alemtuzumab) and CD20 antigen (rituximab) also demonstrate significant activity in CLL and should be used in patients with disease that is refractory to PNAs. Combination therapies with PNAs and cyclophosphamide, and especially with rituximab, are more active than monotherapy with PNAs in regard to response rate and possible survival. Because most patients are older and there is no survival time advantage for alkylating agents or PNA therapies, we recommend chlorambucil as the first-line treatment, with PNAs for consideration as the second-line therapy. PNAs alone or in combination with cyclophosphamide and rituximab as first-line treatment are an option in younger patients, who may be candidates for consolidation therapy with alemtuzumab and/or stem cell transplantation. Alemtuzumab may be an effective treatment for patients refractory to PNAs. Several biological parameters have been gaining increasing importance to evaluate the prognosis of patients with CLL and define optimal therapeutic strategy. Moreover, novel therapies are being evaluated, especially in patients refractory to PNAs, including those targeting the antiapoptotic bcl-2 family of proteins and receptors, vaccines, and allogenic stem cell transplantation, especially after nonmyeloablative chemotherapy.

Revisiting the role of hematopoietic stem cell transplantation in chronic lymphocytic leukemia

Since the advent of hematopoietic stem cell transplantation more than 40 years ago, numerous methods of transplantation have been developed, modified and improved upon. Although hematopoietic stem cell transplantation has been used in a variety of malignant diseases since then, its use in the treatment of chronic lymphocytic leukemia has recently started to gain interest. Patients with chronic lymphocytic leukemia are generally elderly, and because of its relatively benign course, they were not considered suitable candidates for hematopoietic stem cell transplantation. Nonetheless, there have been marked improvements in transplantation techniques, including better conditioning regimens that have decreased treatment-related morbidity and mortality. In this article, the authors review the most recent data on hematopoietic stem cell transplantation in chronic lymphocytic leukemia as well as the change in risk stratification based on newer prognostic factors and its impact on treatment decisions in chronic lymphocytic leukemia.

Touch-Down Reverse Transcriptase-PCR Detection of IgVH Rearrangement and Sybr-Green-Based Real-Time RT-PCR Quantitation of Minimal Residual Disease in Patients with Chronic Lymphocytic Leukemia

BACKGROUND

Patients with chronic lymphocytic leukemia (CLL) can relapse even after aggressive therapy and autografts. It is commonly assumed that to prevent relapse the level of minimal residual disease (MRD) should be as low as possible. To evaluate MRD, highly sensitive quantitative assays are needed.

AIM

The aim of the study was to develop a robust and sensitive method for detection of the clonal immunoglobulin heavy-chain variable (IgV(H)) rearrangement in CLL and to introduce a highly sensitive and specific methodology for MRD monitoring in patients with CLL who undergo intensive treatment.

METHODS

As a prerequisite for MRD detection, touch-down reverse transcriptase (RT)-PCR using degenerate primers were used for the diagnostic identification of (H) gene rearrangement(s). For quantitative MRD detection in 18 patients, we employed a real-time RT-PCR assay (RQ-PCR) making use of patient-specific primers and the cost-saving Sybr-Green reporter dye (SG). For precise calibration of RQ-PCR, patient-specific IgV(H) sequences were cloned.

RESULTS

Touch-down RT-PCR with degenerate primers allowed the successful detection of IgV(H) clonal rearrangement(s) in 252 of 257 (98.1%) diagnostic samples. Biallelic rearrangements were found in 27 of 252 (10.7%) cases. Degenerate primers used for the identification of clonal expansion at diagnosis were not sensitive enough for MRD detection. In contrast, our RQ-PCR assay using patient-specific primers and SG reached the sensitivity of 10(-)(6). We demonstrated MRD in each patient tested, including four of four patients in complete remission following autologous hematopoietic stem cell transplantation (HSCT) and three of three following allogeneic 'mini'-HSCT. Increments in MRD might herald relapse; aggressive chemotherapy could induce molecular remission.

CONCLUSIONS

Our touch-down RT-PCR has higher efficiency to detect clonal IgV(H) rearrangements including the biallelic ones. MRD quantitation of IgV(H) expression using SG-based RQ-PCR represents a highly specific, sensitive, and economic alternative to the current quantitative methods.

Therapy of Chronic Lymphocytic Leukaemia with Purine Nucleoside Analogues

Chronic lymphocytic leukaemia (CLL) is a neoplastic disease of unknown aetiology characterised by an absolute lymphocytosis in peripheral blood and bone marrow. The disease is diagnosed most commonly in the elderly with the median age at diagnosis being about 65 years. The purine nucleoside analogues (PNAs) fludarabine, cladribine (2-chlorodeoxyadenosine) and pentostatin (2'-deoxycoformycin) are highly active in CLL, both in previously treated and in refractory or relapsed patients. These three agents share similar chemical structures and mechanisms of action such as induction of apoptosis. However, they also exhibit significant differences, especially in their interactions with enzymes involved in adenosine and deoxyadenosine metabolism. Recent randomised studies suggest that fludarabine and cladribine have similar activity in CLL. However, clinical observations indicate the existence of cross-resistance between fludarabine and cladribine. Patients who received PNAs as their initial therapy and achieved long-lasting response can be successfully retreated with the same agent. PNAs administered in combination with other chemotherapeutic agents and/or monoclonal antibodies may produce higher response rates, including complete response (CR) or molecular CR, compared with PNAs alone or other treatment regimens. Management decisions are more difficult in elderly patients because of the apparent increase in toxicity of PNAs in this population. In elderly patients, we recommend chlorambucil as the first-line treatment, with PNAs in lower doses in refractory or relapsed patients. Myelosuppression and infections, including opportunistic varieties, are the most frequent adverse effects in patients with CLL treated with PNAs. Therefore, some investigators recommend routine antibacterial and antiviral prophylaxis during and after PNA treatment. This review presents current results and treatment strategies with the use of PNAs in CLL, especially in elderly patients.