Salvage Therapy for CLL and the Role of Stem Cell Transplantation

Comparison of the blood immune repertoire with clinical features in chronic lymphocytic leukemia patients treated with chemoimmunotherapy or ibrutinib

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD19+ CD5+ clonal B lymphocytes in the blood, bone marrow, and peripheral lymphoid organs. Treatment options for patients range from historical chemoimmunotherapy (CIT) to small molecule inhibitors targeting pro-survival pathways in leukemic B cells, such as the Bruton's tyrosine kinase inhibitor ibrutinib (IBR). Using biobanked blood samples obtained pre-therapy and at standard response evaluation timepoints, we performed an in-depth evaluation of the blood innate and adaptive immune compartments between pentostatin-based CIT and IBR and looked for correlations with clinical sequelae. CD4+ conventional T cells and CD8+ cytotoxic T cells responded similarly to CIT and IBR, although exhaustion status differed. Both treatments dramatically increased the prevalence and functional status of monocyte, dendritic cell, and natural killer cell subsets. As expected, both regimens reduced clonal B cell levels however, we observed no substantial recovery of normal B cells. Although improvements in most immune subsets were observed with CIT and IBR at response evaluation, both patient groups remained susceptible to infections and secondary malignancies during the study.

Application of a sequential multiple assignment randomized trial (SMART) design in older patients with chronic lymphocytic leukemia

BACKGROUND

Ibrutinib therapy is safe and effective in patients with chronic lymphocytic leukemia (CLL). Currently, ibrutinib is administered continuously until disease progression. Combination regimens with ibrutinib are being developed to deepen response which could allow for ibrutinib maintenance (IM) discontinuation. Among untreated older patients with CLL, clinical investigators had the following questions: (i) does ibrutinib + venetoclax + obinutuzumab (IVO) with IM have superior progression-free survival (PFS) compared with ibrutinib + obinutuzumab (IO) with IM, and (ii) does the treatment strategy of IVO + IM for patients without minimal residual disease complete response (MRD- CR) or IVO + IM discontinuation for patients with MRD- CR have superior PFS compared with IO + IM.

DESIGN

Conventional designs randomize patients to IO with IM or IVO with IM to address the first objective, or randomize patients to each treatment strategy to address the second objective. A sequential multiple assignment randomized trial (SMART) design and analysis is proposed to address both objectives.

RESULTS

A SMART design strategy is appropriate when comparing adaptive interventions, which are defined by an individual's sequence of treatment decisions and guided by intermediate outcomes, such as response to therapy. A review of common applications of SMART design strategies is provided. Specific to the SMART design previously considered for Alliance study A041702, the general structure of the SMART is presented, an approach to sample size and power calculations when comparing adaptive interventions embedded in the SMART with a time-to-event end point is fully described, and analyses plans are outlined.

CONCLUSION

SMART design strategies can be used in cancer clinical trials with adaptive interventions to identify optimal treatment strategies. Further, standard software exists to provide sample size, power calculations, and data analysis for a SMART design.

How and when I do allogeneic transplant in CLL

Allogenic stem cell transplantation (allo-SCT) has been considered the treatment of choice for high-risk patients with chronic lymphocytic leukemia (CLL) and the only approach offered with curative intent in this disease. The availability novel agents, including the B-cell receptor inhibitors ibrutinib, acalabrutinib, and idelalisib, as well as venetoclax, which targets the BCL2 pathway, and the success of these agents in treating high-risk disease patients have made it more difficult to assess who should be considered for allo-SCT and when in the treatment course. In this review, I will discuss the different treatment options available for the treatment of high-risk CLL and how allo-SCT fits into the treatment algorithm in the era of novel agents.

Is bendamustine an ideal partner for rituximab in the management of relapsed chronic lymphocytic leukemia? Results of a multicenter Phase II trial

First-line chemoimmunotherapy approaches offer prolonged disease-free survival in patients with chronic lymphocytic leukemia (CLL). Despite the improved results with purine analogs ± cyclophosphamide and rituximab (FCR) the disease remains incurable, and patients with CLL are destined to relapse after primary treatment. The prior therapy administered and the response, and duration of response to that therapy, are among the most important factors in determining the next therapy. Bendamustine, a bifunctional alkylating agent, combined with rituximab (BR) has been tested in patients with relapsed and/or refractory CLL in order to investigate the safety and efficacy of this combination. In conclusion, chemoimmunotherapy with BR showed interesting results, with the exception of patients carrying del(17p). Bendamustine appears to be a good choice for second-line therapy owing to its lack of significant cross-resistance with other alkylating agents or fludarabine.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: Report from the Committee on Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse is a major cause of treatment failure after allogeneic hematopoietic stem cell transplantation (alloHSCT). Treatment options for relapse have been inadequate, and the majority of patients ultimately die of their disease. There is no standard approach to treating relapse after alloHSCT. Withdrawal of immune suppression and donor lymphocyte infusions are commonly used for all diseases; although these interventions are remarkably effective for relapsed chronic myelogenous leukemia, they have limited efficacy in other hematologic malignancies. Conventional and novel chemotherapy, monoclonal antibody therapy, targeted therapies, and second transplants have been utilized in a variety of relapsed diseases, but reports on these therapies are generally anecdotal and retrospective. As such, there is an immediate need for well-designed, disease-specific trials for treatment of relapse after alloHSCT. This report summarizes current treatment options under investigation for relapse after alloHSCT in a disease-specific manner. In addition, recommendations are provided for specific areas of research necessary in the treatment of relapse after alloHSCT.

Standards for the treatment of relapsed chronic lymphocytic leukemia: a case-based study

In recent years, considerable advances have been made in first-line treatment strategies for chronic lymphocytic leukemia (CLL). Combination of conventional chemotherapy with immunotherapeutic agents is currently considered the most active strategy, with improved progression-free survival and overall survival. However, patients are not cured and invariably experience relapsing disease requiring treatment. In contrast to the advances made in first-line treatment strategies, much less progress has been made for patients with relapsed and especially refractory CLL. The activity of most chemotherapeutic drugs used in CLL rely on intact p53 function, and repeated cycles of therapy might eventually result in drug resistance because of acquired cytogenetic alterations, mainly affecting genes involved in the p53 response. As a consequence, most commonly used treatment regimens are ineffective in patients with refractory disease. A number of promising alternative treatment approaches are currently under investigation. In this review, the approach to patients with relapsed and refractory CLL and current promising experimental treatment options for these distinct clinical patient categories are discussed.

The treatment of recurrent/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) with everolimus results in clinical responses and mobilization of CLL cells into the circulation

BACKGROUND

Patients with recurrent/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) often have chemotherapy-resistant disease, resulting in poor prognosis. The aim of this study was to learn if inhibition of the mammalian target of rapamycin (mTOR) would produce tumor responses.

METHODS

This was a phase 2 study of oral single-agent everolimus (10 mg/day) for recurrent/refractory indolent lymphoid malignancies including CLL.

RESULTS

Four of 22 patients with CLL (18%; 95% confidence interval, 5%-40%) achieved a partial remission to therapy. An unanticipated finding in this study was an increase in absolute lymphocyte count (ALC) associated with a decrease in lymphadenopathy in 8 (36%) patients. ALC increased a median of 4.8-fold (range, 1.9- to 25.1-fold), and the clinically measurable lymphadenopathy decreased a median of 75.5% (range, 38%-93%) compared with baseline measurements.

CONCLUSIONS

Everolimus has modest antitumor activity against CLL and can mobilize malignant cells from nodal masses into the peripheral circulation in a subset of CLL patients. Because CLL cells in lymphatic tissue and bone marrow can be more resistant to therapy than circulating CLL cells, the ability of everolimus to mobilize CLL cells into the circulation could be used in combination therapeutic regimens.

Chronic lymphocytic leukemia: biology and current treatment

There has been considerable recent progress in understanding of the biology of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL). These accomplishments have been accompanied by progressive improvement in the management of CLL and its complications. This review summarizes these changes and provides guidelines for a comprehensive approach to patient care.

Recent progress in the management of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a clonal disease characterized by proliferation and accumulation of small CD5-positive B cells. More than 50% of patients are asymptomatic at diagnosis and usually require no treatment. However, treatment is needed in the advanced and progressive disease. Chlorambucil with or without steroids has been the drug of choice for many years in previously untreated patients with CLL. The purine nucleoside analogs (PNAs), fludarabine (FA), cladribine (2-CdA-chlorodeoxyadenosine) and pentostatin (DCF, 2'-deoxycoformycin) also have been introduced for treatment of CLL. Significantly higher overall response (OR) and complete response (CR) and longer progression free survival (PFS) in patients with CLL treated with FA or 2-CdA have been confirmed in randomized, multicenter trials and more recently in meta-analysis. However, the median survival time did not differ between patients treated with PNA and alkylating agents. Combination therapies with PNAs and cyclophosphamide and especially with cyclophosphamide and rituximab are more active than monotherapy in terms of OR, CR and PFS. Several reports have shown significant activity of alemtuzumab in previously untreated and pretreated patients even when refractory to FA. Alemtuzumab also can be used in CLL as a preparative regimen before stem cell transplantation (SCT) and to eliminate minimal residual disease (MRD). Recently, several new agents have shown promise in treating CLL, including new monoclonal antibodies, agents targeting bcl-2 family of proteins, antisense oligonucleotides and other agents. Moreover, autologous and allogenic hematopoietic cell transplantations are increasingly considered for treatment of patients with CLL. In this review current therapeutic strategies in CLL are presented.

Positive selection and transplantation of autologous highly purified CD133(+) stem cells in resistant/relapsed chronic lymphocytic leukemia patients results in rapid hematopoietic reconstitution without an adequate leukemic cell purging

We assessed the capacity of positively selected autologous CD133(+) hematopoietic stem cells (HSCs) to reconstitute lymphomyelopoiesis in chronic lymphocytic leukemia (CLL) patients receiving myeloablative chemotherapy. Ten resistant/relapsed CLL patients underwent HSC mobilization with chemotherapy and granulocyte-colony stimulating factor (G-CSF). Positive selection of circulating CD133(+) HSCs was performed by immunomagnetic technique. Highly purified HSCs were reinfused after busulphan/melphalan myeloablative treatment. A median number of 4.2 x 10(6) CD34(+) cells/kg and of 3.14 x 10(6) CD133(+) cells/kg were collected. Immunomagnetic selection resulted in the reinfusion of a median number of 2.45 x 10(6) CD133(+) cells/kg (median purity: 94.8%; median recovery: 84%) and 2.4 x 10(6) CD34(+) cells/kg (median purity: 93%; median recovery: 71%). HSC selection resulted in a median T cell and CD19(+)/CD5(+) cell depletion of 3.85 log and 2.8 log, respectively. At the molecular level, however, 7 of 8 valuable purified HSC fractions were contaminated by leukemic cells. All CLL patients showed rapid and sustained myeloid engraftment after reinfusion of purified CD133(+) cells. Immunologic reconstitution was comparable to that routinely observed in patients reinfused with unmanipulated leukapheresis products and no late infectious complications were observed. With a median follow-up of 28 months for transplanted patients, 5 patients are in clinical complete remission, 3 are in partial remission, and 1 is in progression. In conclusion, the reinfusion of highly purified CD133(+) HSCs allowed the rapid and sustained recovery of hematopoiesis after myeloablative treatment in resistant/relapsed CLL patients. However, the purging potential of positive selection of CD133(+) cells is not adequate to achieve tumor-free autografts.

Comprehensive assessment of genetic and molecular features predicting outcome in patients with chronic lymphocytic leukemia: results from the US Intergroup Phase III Trial E2997

PURPOSE

Genomic features including unmutated immunoglobulin variable region heavy chain (IgVH) genes, del(11q22.3), del(17p13.1), and p53 mutations have been reported to predict the clinical course and overall survival of patients with chronic lymphocytic leukemia (CLL). In addition, ZAP-70 and Bcl-2 family proteins have been explored as predictors of outcome.

PATIENTS AND METHODS

We prospectively evaluated the prognostic significance of a comprehensive panel of laboratory factors on both response and progression-free survival (PFS) using samples and data from 235 patients enrolled onto a therapeutic trial. Patients received either fludarabine (FL; n = 113) or fludarabine plus cyclophosphamide (FC; n = 122) as part of a US Intergroup randomized trial for previously untreated CLL patients.

RESULTS

Complete response (CR) rates were 24.6% for patients receiving FC and 5.3% for patients receiving FL (P = .00004). PFS was statistically significantly longer in patients receiving FC (median, 33.5 months for patients receiving FC and 19.9 months for patients receiving FL; P < .0001). The occurrence of del(17p13.1) (hazard ratio, 3.428; P = .0002) or del(11q22.3) (hazard ratio, 1.904; P = .006) was associated with reduced PFS. CR and overall response rates were not significantly different based on cytogenetics, IgVH mutational status, CD38 expression, or p53 mutational status. Expression of ZAP-70, Bcl-2, Bax, Mcl-1, XIAP, Caspase-3, and Traf-1 was not associated with either clinical response or PFS.

CONCLUSION

These results support the use of interphase cytogenetic analysis, but not IgVH, CD38 expression, or ZAP-70 status, to predict outcome of FL-based chemotherapy. Patients with high-risk cytogenetic features should be considered for alternative therapies.

Update on risk-stratified management for chronic lymphocytic leukemia

Major recent advances in understanding the biology of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) have improved clinical evaluation and influenced treatment decisions. CLL can be diagnosed early and accurately, and biological measurements can be used to predict a prognosis at diagnosis. Individual patient care can be risk stratified to optimize benefit and minimize complications of therapy. Purine analogs and monoclonal antibodies have markedly improved the efficacy of initial therapy but are not curative. The treatment of relapsed and refractory CLL is less successful. However, recent developments suggest that allogeneic stem cell transplant could have a larger role in a selected group of these patients. Potential new treatment modalities include targeted molecules that interrupt key components of CLL cell survival pathways, and active and passive immunotherapy. The management of CLL is in a dynamic phase of rapid evolution. Risk stratification using biological prognostic markers can improve current patient care and direct future clinical research.

Indications for allogeneic stem cell transplantation in chronic lymphocytic leukemia: the EBMT transplant consensus

The aim of this project was to identify situations where allogeneic stem cell transplantation (allo-SCT) might be considered as a preferred treatment option for patients with B-cell chronic lymphocytic leukemia (CLL). Based on a MEDLINE search and additional sources, a consented proposal was drafted, refined and approved upon final discussion by an international expert panel. Key elements of the consensus are (1) allo-SCT is a procedure with evidence-based efficacy in poor-risk CLL; (2) although definition of 'poor-risk CLL' requires further investigation, allo-SCT is a reasonable treatment option for younger patients with (i) non-response or early relapse (within 12 months) after purine analogues, (ii) relapse within 24 months after having achieved a response with purine-analogue-based combination therapy or autologous transplantation, and (iii) patients with p53 abnormalities requiring treatment; and (3) optimum transplant strategies may vary according to distinct clinical situations and should be defined in prospective trials. This is the first attempt to define standard indications for allo-SCT in CLL. Nevertheless, whenever possible, allo-SCT should be performed within disease-specific prospective clinical protocols in order to continuously refine transplant indications according to new developments in risk assessment and treatment of CLL.