Novel Immune-Based Treatment Strategies for Chronic Lymphocytic Leukemia Williamg.Wierda,Thomasj.Kipps,Andmichaelj.Keating

VOLUME 23 d NUMBER 26 d SEPTEMBER 10 2005

JOURNAL OF CLINICAL ONCOLOGY REVIEW ARTICLE

Novel Immune-Based Treatment Strategies for Chronic Lymphocytic Leukemia WilliamG.Wierda,ThomasJ.Kipps,andMichaelJ.Keating

From the Department of Leukemia, Division of Cancer Medicine, The ABSTRACT University of Texas M.D. Anderson Cancer Center, Houston, TX; Immune-based treatments represent a new group of therapeutic strategies for patients with Department of Medicine, Division of cancer, including chronic lymphocytic leukemia (CLL), that employ immune effector mecha- Hematology and Oncology, University nisms. Among these strategies is passive immunotherapy with monoclonal antibody, alone or of California, San Diego, San Diego, in combination with chemotherapy. Active immunotherapy strategies currently under devel- CA; and the Chronic Lymphocytic Leukemia Research Consortium, opment include vaccines, administration of expanded and activated T cells, and allogeneic San Diego, CA. stem cell transplantation. These immune-based strategies represent new treatments with potentially complementary mechanisms of action to standard therapies and signify major ad- Submitted May 5, 2005; accepted May 17, 2005. vances in treatments for patients with CLL.  Authors’ disclosures of potential J Clin Oncol 23:6325-6332. 2005 by American Society of Clinical Oncology conflicts of interest are found at the end of this article. INTRODUCTION This review will discuss these immuno- Address reprint requests to William G. logic treatment strategies and review out- Wierda, MD, PhD, The University of Immune-based treatment strategies offer Texas M.D. Anderson Cancer Center, comes of clinical trials using immune-based Department of Leukemia, 1515 exciting new treatment options for patients treatment strategies in patients with CLL. Holcombe Blvd, Unit 428, Houston, with chronic lymphocytic leukemia (CLL). TX 77030; e-mail: wwierda@ Certainly, harnessing and utilizing the mdanderson.org. mAb THERAPY immune system’s great potential as a thera-  2005 by American Society of Clinical The binding of an mAb to its respective an- peutic modality against malignancy offers Oncology tigen on the surface of the CLL B cells can a unique and powerful spectrum of tools 0732-183X/05/2326-6325/$20.00 target the neoplastic cell for destruction distinct from traditional chemotherapy. DOI: 10.1200/JCO.2005.05.008 through a variety of mechanisms. One Passive immune therapy involves trans- such mechanism is antibody-dependent cel- fer of antigen-specific antibodies to an indi- lular cytotoxicity. In addition, leukemia cells vidual and is effective in patients with CLL coated with bound mAb may be targeted for (Table 1). Molecular biology has enabled clearance by the reticuloendothelial system. production of large amounts of monoclonal Another mechanism may be through com- antibody (mAb) directed against surface pliment activation leading to lysis of the antigens found on CLL B cells. Such mAbs antibody-bound target cell. Finally, the can be used alone or in combination with binding of mAb to certain surface proteins chemotherapeutic agents in the treatment on leukemia cells may directly kill leukemia of patients with CLL. Already, mAbs such cells by activating an apoptotic cascade or by as alemtuzumab and rituximab have signif- blocking the binding of signaling factors icantly advanced the treatment of CLL. responsible for maintaining leukemia-cell Active immune therapy invokes adap- viability, both independent of extrinsic tive immunity and is induced by exposure effector mechanisms. to antigen, thereby inducing specific lymphocyte responses (Table 1). Specifically, Alemtuzumab vaccine strategies are being developed Alemtuzumab (anti-CD52 mAb; that induce or enhance T-cell responses Campath-1H) is a humanized mAb specific against autologous leukemia cells. for CD52, a surface proteins present on

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Table 1. Immune-Based Treatment Strategies for CLL Immunotherapy Target Clinical Trial Passive Monoclonal antibodies Alemtuzumab CD52 Phase II Rituximab CD20 Phase II Lumiliximab CD23 Phase I LYM-1 HLA-DR Phase II Apolizumab HLA-DR-␤ Phase I CHIR-12.12 CD40 Phase I Active Modified autologous leukemia-cell vaccine Ad-CD154–modified autologous CLL B cells Unselected leukemia antigens Phase I Oxidized autologous CLL B cells Unselected leukemia antigens Phase I Autologous dendritic-cell vaccine Antigen-pulsed autologous dendritic cells Selected antigen v unselected leukemia antigens Phase I/II Activated autologous T cells Xcellerate T cells Unidentified leukemia antigen Phase I/II Adoptive Allogeneic stem cell transplantation Donor hematopoietic cells (myeloablative v Unidentified leukemia antigen Phase II nonmyeloablative conditioning) Abbreviation: CLL, chronic lymphocytic leukemia.

CLL B cells as well as normal B and T cells.1 Alemtuzumab with alemtuzumab provided benefit for patients was approved by the US Food and Drug Administration as with very poor prognosis. Subsequent studies confirmed a single agent for patients with fludarabine-refractory CLL. the activity of alemtuzumab in previously treated patients In the pivotal trial, alemtuzumab was administered to with CLL and when administered via subcutaneous (SQ) fludarabine-refractory patients at a standard dose of 30 administration.3-7 Higher response rates were observed in mg intravenous (IV) three times weekly for a total of 12 chemotherapy-naı¨ve patients who receive alemtuzumab as weeks (Table 2).2 The overall objective response in 93 pa- front-line therapy.8 Alemtuzumab 30 mg SQ three times tients was 33%, with 2% complete remission (CR) and weekly for up to 18 weeks produced 19% CR and 68% 31% partial remission (PR). The median time to progres- PR in 38 previously untreated patients with CLL. A sion for responders was 9.5 months; clinical benefit was number of these studies found that alemtuzumab was noted in both responders and those with stable disease. highly effective in clearing leukemia cells from the blood The overall median survival was 16 months, 32 months and marrow, but less active in clearing bulky lymph for responders. Notable infections occurred in a little nodes. Also, alemtuzumab may be effective in clearing more than a quarter of the patients. Overall, treatment leukemia cells that lack p53 function.9,10 Such leukemia

Table 2. Passive Immunotherapy of CLL With Single-Agent Monoclonal Antibody Prior No. of Patients Complete Overall Median TTP Monoclonal Antibody Study Treatment Assessable Remission (%) Response (%) (months) Alemtuzumab 30 mg IV TIW ϫ 12 Keating2 Yes* 93 2 33 9.5 30 mg IV TIW ϫ 12 Osterborg3 Yes 29 4 42 12 30 mg IV TIW ϫ 16 Rai5 Yes 24 0 33 19.6 30 mg IV TIW ϫ 12 Ferrajoli6 Yes 42 5 31 NA 30 mg SQ TIW ϫ 18 Lundin8 No 41 19 87 NA Rituximab 375 mg/m2 weekly ϫ 4 McLaughlin15 Yes 30 0 13 NA 375 mg/m2 weekly ϫ 4 Winkler16 Yes 9 0 11 NA 375 mg/m2 weekly ϫ 4 Nguyen17 Yes 12 0 0 NA 375 mg/m2 weekly ϫ 4 Huhn18 Yes 28 0 25 5 500-825 mg/m2 weekly ϫ 4 O’Brien20 Yes 24 0 21 1,000-1,500 mg/m2 weekly ϫ 4 Yes 7 0 43 8 2,250 mg/m2 weekly ϫ 4 Yes 8 0 75 375 mg/m2 TIW ϫ 4 weeks† Byrd19 No/Yes 29 4 52 11 375 mg/m2 weekly ϫ 4, then every Hainsworth21,22 No 43 9 58 19 6 months for 2 years Abbreviations: CLL, chronic lymphocytic leukemia; TTP, time-to-progression for responders; TIW, three times weekly; IV, intravenous; SQ, subcutaneous; NA, not available. *Fludarabine refractory. †Three patients received 250 mg/m2 TIW for 4 weeks.

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Information downloaded from jco.ascopubs.org and provided by at Christian Medical College-Vellore on August 9, 2011 from Copyright © 2005 American Society220.225.126.138 of Clinical Oncology. All rights reserved. Immunotherapies for CLL cells may be resistant to standard antileukemia drugs such Rituximab was administered concurrently at 375 mg/m2 as chlorambucil or purine analogs. Finally, in CLL the weekly for all 4 weeks. Responses were reported for 48 efficacy of alemtuzumab does not appear to be affected patients: 32 with CLL, nine with CLL/prolymphocytic by Fc receptor polymorphisms.11 leukemia (PLL), one with PLL, four with mantle-cell lymphoma, and two with Richter’s transformation. The over- Rituximab all response rate was 52%; CR was noted in 8%, nodular Rituximab (anti-CD20 mAb) is a humanized mAb PR (nPR) in 4%, and PR in 40% of treated patients. The that binds to human CD20.12 Relatively low levels of median time to progression and overall survival were 6 CD20 typically are expressed on CLL B cells compared and 11 months, respectively. Toxicities included infusion- with that expressed by normal or neoplastic B cells of other related reactions. Infections occurred in 52% of patients lymphomas.13 Also, the plasma of patients with CLL may with cytomegalovirus reactivation occurring in 27% of pa- contain soluble CD20 that can inhibit the capacity of tients. Overall, this was a well-tolerated combination for rituximab to bind to CLL B cells in vivo.14 This likely relapsed patients with CLL. influences the pharmacokinetics and clinical activity of rituximab in patients with CLL. At the standard dose of Lumiliximab 375 mg/m2 weekly for 4 weeks, single-agent rituximab Lumiliximab (anti-CD23 mAb) is a macaque-human had only modest anti–leukemia cell activity in CLL (Table chimeric antihuman CD23 mAb that has been evaluated in 2).15-18 Studies demonstrated that dose-intense or dose- a phase I clinical trial for previously treated patients with dense administration of rituximab significantly improved CLL.25 Increasing doses of lumiliximab up to 500 mg/m2 response rates.19,20 O’Brien et al20 evaluated higher doses three times weekly for 4 weeks were studied. No dose- ranging to as high as 2.25 gm/m2 weekly for 4 weeks. The limiting toxicities were identified, and decreases in abso- overall response rate in previously treated patients treated lute lymphocyte counts were noted in more than 90% in this dose escalation study was 40%, with significantly of the patients; reduction of 50% or more occurred in higher response rates observed at higher doses. However, more than one fourth of patients. Reduction in lymph none of these previously treated patients achieved CR. node size occurred in 59%. However, there were no com- Using a dose-dense schedule of 375 mg/m2 three times plete or partial responders by National Cancer Institute weekly for 4 weeks, Byrd et al19 observed a CR rate of criteria in this phase I trial. Lumiliximab is currently being 3% and PR rate of 42% (45% overall) in 33 patients evaluated in combination chemoimmunotherapy regimens. with CLL. Rituximab also has been evaluated as a single agent in Apolizumab previously untreated patients with CLL, using 375 mg/m2 The mAb apolizumab (HU1D10; anti-MHC II) binds of rituximab weekly for 4 weeks with subsequent mainte- an epitope found on the alpha-chain of HLA-DR.26 This nance therapy consisting of the same at six-month inter- epitope is found on HLA-DR expressed on B cells and vals for a total of two years.21,22 There were a total of 44 monocytes of healthy donors as well as on the leukemia small lymphocytic lymphoma/CLL chemotherapy-naı¨ve B cells of many patents with CLL. Apolizumab can directly patients enrolled on this trial. Following the first course induce apoptosis in primary lymphoma and CLL B cells.26 of rituximab, the complete and overall response rates A phase I clinical trial with increasing doses of apolizumab were 4% and 51%, and 49% had stable disease after ther- for four weekly infusions was conducted in patients with apy. The complete and overall response rates upon com- lymphoma.27 Subsequently, a phase I study of thrice- pletion of therapy were 9% and 58%, respectively. The weekly apolizumab was conducted in patients with estimated median progression-free time was 19 months. relapsed or refractory CLL.28 At last report, it appeared Overall, single-agent rituximab was well tolerated, how- that the maximum-tolerated dose of apolizumab was ever, much higher response rates have been seen when rit- 3 mg/kg IV three times weekly for 4 weeks. Pharmacody- uximab is combined with chemotherapy. Finally, unlike namic studies demonstrated phosphorylation of the pro- the responses to rituximab in other B cell malignancies tein akt in CLL B cells of apolizumab-treated patients.29 (eg, follicular lymphoma), the response to rituximab for Such studies suggest that apolizumab may induce both patients with CLL does not appear to be affected by Fc re- death and survival signals in CLL B cells. ceptor polymorphisms.23 Combined Alemtuzumab and Rituximab Anti-CD40 mAb The combination of alemtuzumab and rituximab has CD40 is a B-cell surface molecule that is ubiquitously been evaluated in patients with relapsed and refractory expressed in CLL. CD40 has functional significance in CLL lymphoid malignancies.24 Alemtuzumab was administered whereby ligation may provide survival and proliferation in a ramp-up dose to 30 mg IV during the first week and signals to the leukemic B cells.30,31 A fully humanized then twice weekly at 30 mg IV for the subsequent 3 weeks. anti-CD40 mAb (CHIR-12.12) has been produced that www.jco.org 6327

Information downloaded from jco.ascopubs.org and provided by at Christian Medical College-Vellore on August 9, 2011 from Copyright © 2005 American Society220.225.126.138 of Clinical Oncology. All rights reserved. Wierda, Kipps, and Keating has blocking activity.32,33 In vitro, this mAb blocks patients receiving concurrent therapy, rituximab was also CD154-mediated stimulation of primary leukemia B cells. administered at 375 mg/m2 day 1 with each course. This Culture of CLL B cells with anti-CD40 mAb induced randomized clinical trial of 104 patients demonstrated sta- apoptosis in primary CLL B cells as well as facilitated tistically significantly higher CR with concurrent versus ϩ ADCC against CD40 targets.32 These in vitro studies sequential therapy. However, patients treated in the group form the rationale for conducting a phase I clinical trial that received concurrent therapy were administered 2.5 of anti-CD40 mAb in previously treated patients with CLL. times the amount of rituximab, compromising head- to-head comparisons between these two groups. Neverthe- CHEMOIMMUNOTHERAPY less, survival advantage has not been demonstrated for Cytotoxic chemotherapy and mAb have synergistic activity either group. In a historical comparison of single-agent in patients with CLL. In vitro, fludarabine downmodu- fludarabine (CALGB 9011), it appeared that previously lates expression of complement-resistance proteins CD49, untreated patients who receive rituximab as part of their CD55 and CD59, possibly making the treated cells more initial therapy may have improved survival over those re- susceptible to rituximab-induced compliment-mediated ceiving single-agent fludarabine.46 lysis.34 Conversely, rituximab downmodulates expression of bcl-2, making leukemia cells more susceptible to Fludarabine and Alemtuzumab fludarabine-induced apoptosis.35 Potential synergy between fludarabine and alemtuzumab was first suggested by a small trial of six patients who Fludarabine and Rituximab were treated with the combination after being refractory to Combinations of rituximab with purine analogue– fludarabine and alemtuzumab when used separately (Ta- based therapy have been evaluated (Table 3). In CALGB ble 3).38 One patient achieved CR by National Cancer In- (Cancer and Leukemia Group B) 9712,36 previously un- stitute criteria, and four patients achieved PR. The FluCam treated patients received six courses of either sequential regimen consists of fludarabine 30 mg/m2 immediately or concurrent fludarabine and rituximab followed followed by alemtuzumab 30 mg IV, both on days 1 2 months later with an additional 4 weeks of single-agent through 3 of each 4-week course for a total of six courses.39 rituximab for responders or patients with stable disease. This regimen has been evaluated in previously treated pa- Fludarabine was administered at the standard dose of tients with reported CR and PR rates of 29% and 56%, re- 25 mg/m2 daily for 5 days of each 4-week course; for those spectively. Elimination of residual disease from blood was

Table 3. Chemoimmunotherapy for Patients With CLL Prior No. Complete Overall Study Treatment Treatment Assessable Remission (%) Response (%) CALGB 971236 Randomized, concurrent: F, 25 mg/m2 days 1-5, No 51 47 90 cycles 1-6; R, 375 mg/m2 days 1, 4, cycle 1, and day 1, cycles 2-6; 2 months observation; R, 375 mg/m2 weekly ϫ 4. Sequential: F,25 mg/m2 days 1-5, cycles 1-6; 2 months No 53 28 77 observation; R, 375 mg/m2 weekly ϫ 4 Schulz37 Overlapping: F, 25 mg/m2 days 1-5, cycles 1-4; R, No/Yes 31 35 87 375 mg/m2 day 1, cycles 3-6 Kennedy38 Concurrent: F, 25 mg/m2 days 1-3; A, 30 mg TIW ϫ 12 Yes* 6 17 83 Elter39 Concurrent: F, 30 mg/m2 days 1-3, cycles 1-6; A, Yes 34 29 85 30 mg days 1-3, cycles 1-6 MDACC Concurrent: F, 25 mg/m2 days 2-4, cycle 1, and days No40 224 71 95 1-3, cycles 2-6; C, 250 mg/m2 days 2-4, cycle 1, and Yes41 177 25 73 days 1-3, cycles 2-6; R, 375 mg/m2 day 1, cycles 1-6 Wierda42† Concurrent: C, 250 mg/m2 days 2-4, cycle 1, and days Yes 31 23 55 1-3, cycles 2-6; F, 25 mg/m2 days 2-4, cycle 1, and days 1-3, cycles 2-6; A, 30 mg days 1, 3, 5, cycles 1-6; R, 375 mg/m2 day 1, cycles 1-6 Lamanna44 Concurrent: P, 4 mg/m2 day 1, cycles 1-6; C, Yes 28 29 79 600 mg/m2 day 1, cycles 1-6; R, 375 mg/m2 day 1, cycles 2-6 Kay43 Concurrent: P, 2 mg/m2 day 1, cycles 1-6; C, No 33 33 97 600 mg/m2 day 1, cycles 1-6; R, 375 mg/m2 day 1, cycles 2-6 Yunus45 Concurrent: R, 375 mg/m2 days 1, 8, 15, 22, 36, 43, 50; No 12 33 50 P, 4 mg/m2 days 8, 15, 22, 36, 43, 50 Abbreviations: CLL, chronic lymphocytic leukemia; A, alemtuzumab; R, rituximab; F, ﬂudarabine; C, cyclophosphamide; P, pentostatin; MDACC, The University of Texas M.D. Anderson Cancer Center. *Refractory to both F and A. †Updated as presented.

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Information downloaded from jco.ascopubs.org and provided by at Christian Medical College-Vellore on August 9, 2011 from Copyright © 2005 American Society220.225.126.138 of Clinical Oncology. All rights reserved. Immunotherapies for CLL achieved in 44%. Therefore, FluCam is a promising regi- Pentostatin, Cyclophosphamide, and Rituximab men for previously treated patients with CLL. Rituximab has been combined with pentostatin and cyclophosphamide (PCR) for chemotherapy-naı¨ve and Fludarabine, Cyclophosphamide, and Rituximab previously treated patients with CLL (Table 3).43,44 In a The combination of fludarabine, cyclophosphamide, trial for previously treated patients, cyclophosphamide was and rituximab (FCR) has been evaluated in both administered at 600 mg/m2 on day 1, pentostatin 4 mg/m2 chemotherapy-naı¨ve as well as previously treated patients on day 1, and rituximab at 375 mg/m2 with each course with CLL (Table 3).40,41 In this regimen, fludarabine and beginning for course 2.44 Courses were administered every cyclophosphamide were administered at 25 mg/m2 and 3 weeks, and all patients received granulocyte colony- 250 mg/m2, respectively, both days 1 through 3; rituxi- stimulating factor (G-CSF) support. At last report, 28 pre- mab was administered 375 mg/m2 day 1, course 1, and viously treated patients with CLL received this regimen 500 mg/m2 day 1, courses 2 through 6. Treatment was and were assessable for response. In this subgroup, 79% every 4 weeks for a total of six courses. In previously un- responded with CR in 29%. This regimen was well toler- treated patients, the CR rate with this regimen was 70% ated, with the principle toxicity being myleosuppression. A and overall response rate was 95%, with most patients similar regimen with a lower dose of pentostatin (2 mg/m2 having no detectable disease by flow cytometry evalua- day 1), also with G-CSF support, was used to treat tion of the bone marrow at the end of therapy.40 The pro- chemotherapy-naı¨ve patients with CLL. A recent report jected failure-free survival at 4 years was 69%. This was of 33 previously untreated patients that received this reg- the highest response rate reported for any regimen in pre- imen indicated that 33% achieved CR, 21% nPR, and 39% viously untreated patients. PR, for an overall response rate of 97%.43 This regimen Relapsed and refractory patients also were treated was well tolerated with nausea and vomiting as the most with FCR. For 177 previously treated patients with a me- common nonhematologic toxicity. Accrual continues to dian of two prior therapies, 25% achieved CR and the both of these clinical trials. overall response rate was 75%. Approximately one third of the complete responders tested had no detectable dis- Alemtuzumab for Residual Disease ease in the bone marrow by polymerase chain reaction For patients who have residual disease after purine evaluation. The estimated median survival for all 177 analogue–based therapy, the marrow has been the major patients was 42 months. Therefore, this regimen also site of involvement. Elimination of residual disease, partic- has significant activity in previously treated patients ularly in marrow, may enhancetreatmentoutcome. Because with CLL.41 of the significant activity of alemtuzumab at clearing blood and marrow of disease, there have been several studies to Cyclophosphamide, Fludarabine, Alemtuzumab, evaluate its ability to eliminate residual disease following and Rituximab chemotherapy.47-51 Onestudyevaluateda4-to8-weekcourse Alemtuzumab was combined with FCR (CFAR) for of thrice-weekly alemtuzumab at a dose of 30 mg IV for re- previously treated patients with CLL (Table 3).42 In this cently treated patients who had achieved PR or had residual regimen, alemtuzumab 30 mg IV on days 1, 3, and 5 of marrow disease documented either morphologically or by each course was added to FCR as administered in previous flow cytometry.47 The overall response (downstaging) in studies for a total of six courses. An early evaluation of 31 this trial was 46% and residual marrow disease was cleared heavily pretreated patients who had a median of four prior in most patients. Lack of response was due most commonly treatments reported CR in 23% and an overall response to residual adenopathy. Molecular remission was achieved rate of 55%. Nearly half of these patients were fludarabine- in some patients after treatment with alemtuzumab. refractory and nearly half had previously received FCR In a study by the German CLL Study Group, patients as salvage therapy. This was a much more heavily pre- who had recently received fludarabine or fludarabine with treated patient group than that treated with FCR in the cyclophosphamide were randomly assigned to observation previously described study, making it difficult to compare versus consolidation with alemtuzumab.50 This trial was complete and overall response rates. Despite the increase terminated early due to significant infection-related toxicity in the incidence of myleosuppression and thrombocytope- in the patients who received alemtuzumab. However, nia in patients treated with CFAR, they did not experi- alemtuzumab was highly effective at eliminating minimal enced a significant increase in major infections over that residual disease with sustained responses and significantly of patients treated with FCR. Owing to the addition of improved disease-related clinical outcome.52 Therefore, alemtuzumab, there was an increase in cytomegalovirus studies to identify optimal dose and schedule of alemtuzu- reactivation with CFAR. CRs were good quality with elim- mab consolidation continue. ination of minimal residual disease from marrow demon- Alemtuzumab has also been evaluated as maintenance strated by two-color flow cytometry. therapy.53 Alemtuzumab 30 mg IV three times weekly was www.jco.org 6329

Information downloaded from jco.ascopubs.org and provided by at Christian Medical College-Vellore on August 9, 2011 from Copyright © 2005 American Society220.225.126.138 of Clinical Oncology. All rights reserved. Wierda, Kipps, and Keating administered for 9 to 12 weeks followed by monthly main- well as bystander cells, thereby inducing them to express tenance dose of 30 mg IV for at least 4 months. Compared co-stimulatory antigens, such as CD80 and CD86. This to an historic group that received standard dose alemtuzu- phenotypic transformation imparts the ability of these mab followed by observation, the 11 heavily pretreated cells to present antigen to autologous T cells. The end re- patients that received maintenance therapy had longer sult was to stimulate an effective T-cell immune response progression-free and overall survival. against autologous leukemia cells. A phase I clinical trial was performed employing this strategy for patients with CELLULAR THERAPY CLL. There were no dose-limiting toxicities noted and The T cells of patients with CLL display phenotypic and there were significant clinical responses noted in several functional defects that are brought about by the presence patients, including reductions in leukemic cell counts of leukemic B cells. These defects result in dysregulation of and in the size of lymph nodes and spleen. Also, treatment T-cell immunity and overall immunosuppression. Current increased numbers of blood T cells, including T cells spe- treatments for CLL, including purine analogues, exacer- cific for autologous leukemic cells. bate immune deficiency by depleting already dysfunctional Cross linking CD40 on CLL B cells also induced phys- T cells, thereby reducing protection from infection. iologic changes in the leukemia cells that made them more A process has been developed in which T cells can be susceptible to apoptosis.56 Expression or upregulation of activated and expanded ex vivo up to 100- to 1,000-fold CD95, the receptor for Fas (CD178), occurred with via a process referred to as the Xcellerate process.54 CD40 ligation. Also, CLL B cells expressed bid, a pro- With this process, T cells are obtained by leukapheresis apoptotic protein that facilitates cross talk between and cultured with magnetic beads coated with mAbs mitochondria-dependent apoptosis and death receptors against CD3 and CD28 in the presence of interleukin-2. such as DR5. Increased expression of bid may make cells During expansion, T cells also may regain their capacity more susceptible to chemotherapy-induced apoptosis. to respond to antigen. DR5, a death-receptor for TNF (tumor necrosis factor) A phase I/II dose-escalation clinical trial with Xceller- -Related Apoptosis Inducing Ligand (TRAIL) also was ated T cells for patients with CLL was recently reported.54 expressed on CLL B cells after CD40 ligation. Before Doses up to 100 ϫ 109 autologous Xcellerated T cells were CD40 activation, CLL B cells were unaffected by ligation administered as a single infusion to patients with CLL. of CD95 or DR5. However, following ligation of CD40 Xcellerated T cells were well tolerated with no dose- the leukemia cells became sensitive to apoptosis induced limiting toxicities reported. The treatment resulted in con- by ligation of CD95 and/or DR5. Greater levels of kil- sistent dose-dependent increases in blood T-cell counts ling were seen when both death-receptors were ligated si- and reduction in the lymph nodes and spleen. In addi- multaneously. Activated T cells express both Fas ligand tion, there were improvements in absolute neutrophil (CD178) and TRAIL, and may function to kill CLL B cells counts, hemoglobin, and platelet counts, suggesting through this mechanism. This provides a potential overall clinical improvement. Disappointingly, reduc- second mechanism of action in addition to T cell– tions in blood leukemia cell counts were not observed. mediated immunity. A phase II clinical trial is planned with Xcellerated T cells A similar strategy of vaccination employed SQ admin- following debulking therapy in previously treated patients istration of autologous CLL B cells modified to express with CLL. CD154 and IL-2.57 In a report, eight patients received treatment with autologous modified leukemia cells on VACCINE STRATEGIES FOR TREATMENT OF CLL this phase I clinical trial. Several of these patients de- Vaccine strategies have been under investigation for many veloped enhanced T-cell reactivity against autologous years for treatment of various malignancies. The rationale CLL B cells. behind vaccine strategies is to induce host cell–mediated In another study, early-stage patients were vaccinated immune responses against autologous malignant cells as with oxidized autologous leukemia cells.58 Clinical re- the modality to eliminate tumor and to provide lasting sponses were noted in five of 18 patients that were protection from recurrence. Various vaccine strategies associated with enhanced T-cell antitumor activity. Six have been studied for patients with CLL, including vacci- patients had stable disease, and six of the 18 patients nation with modified autologous leukemic cells and use of had progression. No significant toxicities were associated antigen-pulsed dendritic cells. with this treatment. One vaccination strategy utilized modified autologous Dendritic cells are highly effective antigen-presenting leukemic cells.55 A replication-defective adenovirus vector cells. They can be primed to take up antigen and then pres- was employed to transduce CLL B cells to express the gene ent it to T cells, resulting in T-cell activation and prolifer- encoding CD154 (CD40 ligand). Upon expression of ation in response to the presented antigen. Dendritic cell CD154, CD40 was cross linked on transduced cells as fusions with autologous tumor cells have been evaluated

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Information downloaded from jco.ascopubs.org and provided by at Christian Medical College-Vellore on August 9, 2011 from Copyright © 2005 American Society220.225.126.138 of Clinical Oncology. All rights reserved. Immunotherapies for CLL as a vaccine strategy for patients with malignancy. Such vaccines. mAbs have therapeutic activity alone and in dendritic cell–based vaccine strategies are currently in de- combination with chemotherapy and have been incorpo- velopment for clinical trial; however, to date there are no rated into standard treatments for patients with CLL. Vac- trial results available in CLL.59-61 cines and cellular therapies are under investigation in clinical trials and have clinical activity. Work continues CONCLUSION toward developing new treatments with immune-based Immune-based strategies can utilize passive or active ef- mechanisms for patients with CLL. fector modalities including mAbs, cellular therapies, and ---

Authors’ Disclosures of Potential Conflicts of Interest Although all authors completed the disclosure declaration, the following authors or their immediate family members indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. For a detailed description of the disclosure categories, or for more information about ASCO’s conflict of interest policy, pleasereferto the AuthorDisclosure Declaration and theDisclosuresof Potential Conflicts of Interest section in Information for Contributors.

Author Name Employment Leadership Consultant Stock Honoraria Research Fund Testimony Other William G Wierda Berlex Laboratories (C), Xcyte Laboratories (C), Ligano Pharm (C ) Thomas J Kipps Berlex (B), Genentech (B) Michael J Keating Berlex (B), Genentech (B) Berlex (B), Genentech (B) Berlex (B), Genentech (B)

Dollar Amount Codes (A) Ͻ $10,000 (B) $10,000-99,999 (C) $ $100,000 (N/R) Not Required

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