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Objectives: Statistical methods to adjust for treatment switching are commonly applied to randomized controlled trials (RCTs) in oncology. Nevertheless, RCTs with extension studies incorporating nonrandomized dropout require consideration of alternative adjustment methods. The current study used a recognized method and a novel method to adjust for treatment switching in relapsing-remitting multiple sclerosis (MS)., Methods: The Cladribine Tablets Treating Multiple Sclerosis Orally (CLARITY) RCT evaluated the efficacy of cladribine versus placebo over 96 weeks. Many (but not all) CLARITY participants enrolled in the 96-week CLARITY extension study; placebo-treated patients from CLARITY received cladribine (PP→LL), and cladribine-treated patients were re-randomized to placebo (LL→PP) or continued cladribine (LL→LL). End points were time to first qualifying relapse (FQR) and time to 3-month and 6-month confirmed disability progression (3mCDP, 6mCDP). We aimed to estimate the effectiveness of the LL→PP treatment strategy compared with a counterfactual (unobserved) PP→PP strategy. We applied the commonly used rank-preserving structural failure time model (RPSFTM) and a novel approach that combined propensity score matching (PSM) with inverse probability of censoring weights (IPCW)., Results: The RPSFTM resulted in LL→PP versus PP→PP hazard ratios (HRs) of 0.48 (95% confidence interval [CI] 0.36-0.62) for FQR, 0.62 (95% CI 0.46-0.84) for 3mCDP, and 0.62 (95% CI 0.44-0.88) for 6mCDP. The PSM+IPCW resulted in HRs of 0.47 (95% CI 0.38-0.63) for FQR, 0.61 (95% CI 0.43-0.86) for 3mCDP, and 0.63 (95% CI 0.40-0.87) for 6mCDP., Conclusions: The PSM+IPCW HRs were consistent with those from the RPSFTM, suggesting that the results were not substantially biased by informative dropout, assuming that all relevant confounders were controlled for. There was no statistical evidence of a reduction in the cladribine treatment effect during the extension period., (Copyright © 2019 ISPOR–The Professional Society for Health Economics and Outcomes Research. Published by Elsevier Inc. All rights reserved.)

Introduction: No standard salvage chemotherapy regimen is available for relapsed or refractory (RR) acute myeloid leukemia (AML). Preclinical data have suggested synergy in vitro between cytarabine and imatinib mesylate (IM) on AML cell growth inhibition. After demonstrating the safety and feasibility in a phase I study, we conducted a phase II clinical study of CLAG (cladribine, cytarabine, granulocyte colony-stimulating factor) regimen combined with IM for patients with RR-AML., Patients and Methods: We performed a single-institution 2-stage phase II study. The primary endpoint was the remission rate measured using the standard AML response criteria. The secondary endpoints included overall survival (OS) and progression-free survival (PFS)., Results: From August 2009 to April 2011, 38 patients were treated at the Moffitt Cancer Center. Their median age was 62 years (range, 26-79 years). Of the 38 patients, 7 (18%) had refractory AML, 19 (50%) had early relapse, and 12 (32%) had late relapse. At the original diagnosis, only 2 patients had favorable risk factors, 18 had intermediate risk, and 16 had poor risk; for 2 patients, the karyotype was missing. The overall response rate for all 38 evaluable patients was 37%. The median OS was 11.1 months (95% CI, 4.8-13.4 months), the median PFS was 4.9 months (95% CI, 1.6-11.7 months). Among the responders, 8 of 14 patients subsequently underwent allogeneic hematopoietic cell transplantation., Conclusion: CLAG plus IM was well tolerated, with encouraging signs of activity in patients with poor-risk AML., (Copyright © 2017 Elsevier Inc. All rights reserved.)

An international phase 2 study combining cladribine and cytarabine (Ara-C) was initiated for patients with refractory, risk-organ-positive Langerhans cell histiocytosis (LCH) in 2005. The protocol, comprising at least two 5-day courses of Ara-C (1 g/m(2) per day) plus cladribine (9 mg/m(2) per day) followed by maintenance therapy, was administered to 27 patients (median age at diagnosis, 0.7 years; median follow-up, 5.3 years). At inclusion, all patients were refractory after at least 1 course of vinblastine (VBL) plus corticosteroid, all had liver and spleen involvement, and 25 patients had hematologic cytopenia. After 2 courses, disease status was nonactive (n = 2), better (n = 23), or stable (n = 2), with an overall response rate of 92%. Median disease activity scores decreased from 12 at the start of therapy to 3 after 2 courses (P < .0001). During maintenance therapy, 4 patients experienced reactivation in risk organs. There were 4 deaths; 2 were related to therapy toxicity and 2 were related to reactivation. All patients experienced severe toxicity, with World Health Organization grade 4 hematologic toxicity and 6 documented severe infections. The overall 5-year survival rate was 85% (95% confidence interval, 65.2%-94.2%). Thus, the combination of cladribine/Ara-C is effective therapy for refractory multisystem LCH but is associated with high toxicity., (© 2015 by The American Society of Hematology.)

Background: We conducted this trial to determine the maximum tolerated dose (MTD) of temsirolimus added to an established regimen comprised of rituximab and cladribine for the initial treatment of mantle cell lymphoma., Patients and Methods: A standard phase I cohort of three study design was utilized. The fixed doses of rituximab and cladribine were 375 mg/m(2) i.v. day 1 and 5 mg/m(2)/day i.v. days 1-5 of a 28-day cycle, respectively. There were five planned temsirolimus i.v. dose levels: 15 mg day 1; 25 mg day 1; 25 mg days 1 and 15; 25 mg days 1, 8 and 15; and 25 mg days 1, 8, 15, and 22., Results: Seventeen patients were treated: three each at levels 1-4 and five at dose level 5. The median age was 75 years (52-86 years). Mantle Cell International Prognostic Index (MIPI) scores were low in 6% (1), intermediate in 59% (10), and high in 35% (6) of patients. Five patients were treated at level 5 without dose limiting toxicity. Hematologic toxicity was frequent: grade 3 anemia in 12%, grade 3 thrombocytopenia in 41%, grade 4 thrombocytopenia in 24%, grade 3 neutropenia in 6%, and grade 4 neutropenia in 18% of patients. The overall response rate (ORR) was 94% with 53% complete response and 41% partial response. The median progression-free survival was 18.7 months., Conclusions: Temsirolimus 25 mg i.v. weekly may be safely added to rituximab and cladribine at 375 mg/m(2) i.v. day 1 and 5 mg/m(2)/day i.v. days 1-5 of a 28-day cycle, respectively. This regimen had promising preliminary activity in an elderly cohort of patients with mantle cell lymphoma., Clinicaltrialsgov Identifier: NCT00787969., (© The Author 2014. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Hairy cell leukemia (HCL) is a rare, indolent B-cell disorder in which single courses of cladribine induce high rates of complete responses. We report on 88 young HCL patients (≤40 years of age at diagnosis) treated with cladribine from the Scripps Clinic HCL Database, of whom 83 were evaluable for response. Seventy-three patients (88%) achieved an initial complete response and 10 (12%) a partial response, with a median response duration of 57 months. Forty-eight patients (58%) relapsed, with a median time to first relapse for all responders of 54 months. Eight patients developed 11 second primary malignancies with an excess frequency of 1.60 (95% confidence interval, 0.80-2.89). Thirteen (15%) patients died with a mortality ratio compared with age-matched normals of 1.85 (95% confidence interval, 1.07-3.18). Median overall survival for all patients following the first cladribine course was 231 months, and 251 months from diagnosis. Single courses of cladribine induce high rates of complete and durable responses in the majority of young HCL patients and are therefore recommended for HCL patients regardless of age.

Background: Splenic marginal zone lymphoma with or without villous lymphocytes (SLVL/SMZL) is an indolent lymphoma that typically affects elderly patients and that has a median survival >10 years. It presents with marked splenomegaly. Treatment is required in symptomatic cases. Splenectomy remains one of the first-line options in patients fit for surgery. The best pharmacological strategy has not yet been identified for poor surgical risk cases. Among different possible chemotherapeutic approaches, purine analogs, alone or in association with Rituximab, seem to be a valid therapeutic choice., Patients and Methods: Fifty SMZL patients were treated with Cladribine ± anti-CD20 monoclonal antibody., Results: Forty-seven of 50 patients were evaluable for response. ORR was 87%: 24 of 47 patients (51%) achieved a complete hematological response (CR), 17 of 47 (36%) a partial response (PR) and 6 (13%) resulted unresponsive. Interestingly, 15 of 24 cases (62%) in CR achieved also a molecular remission. After a median follow-up of 48 months, 7 of 41 responsive cases relapsed and the 5-year PFS was 80%., Conclusions: These data confirm the efficacy of this schedule emphasizing the impact of minimal residual disease even in the outcome of SMZL patients.

We conducted this study to determine the feasibility and safety of cladribine followed by rituximab in patients with hairy cell leukemia including the vari-ant form (HCLv). Cladribine 5.6 mg/m² given IV over 2 hours daily for 5 days was followed ∼ 1 month later with rituximab 375 mg/m² IV weekly for 8 weeks. Responses were recorded and BM minimal residual disease (MRD) was evaluated after the completion of rituximab. Thirty-six patients have been treated including 5 with HCLv. Median age was 57 years (range, 37-89). All patients (100%) have achieved complete response (CR), defined as presence of no hairy cells in BM and blood with normalization of counts (absolute neutrophil count [ANC]> 1.5 × 10⁹/L, hemoglobin [Hgb] > 12.0 g/dL, platelets [PLT] > 100 × 10⁹/L), as well as resolution of splenomegaly. There were no grade 3 or 4 nonhematologic adverse events directly related to the treatment. Only 1 patient (with HCLv) has relapsed; median CR duration has not been reached (range,1+-63+ months). Three patients with HCLv died including 1 with relapsed disease and 2 from unrelated malignancies. Median survival duration has not been reached (range, 2+-64+ months). Treatment with cladribine followed by rituximab is effective tk;4and may increase CR rate. This study was registered at www.clinicaltrials.gov as NCT00412594.

Cladribine (2-chlorodeoxyadenosine, 2-CdA) treatment-associated infections may shorten potentially long-term survival in hairy cell leukemia (HCL). In search of the optimal mode of 2-CdA administration, 132 patients with untreated HCL were randomized to receive either standard 5-day 2-CdA protocol or a novel schedule of 6 weekly 2-CdA infusions suggested to be less toxic. Analysis of treatment response confirmed similar complete remission rates, overall response rates, progression-free survival, and overall survival in both 2-CdA protocols. However, we did not observe lower toxicity in the weekly schedule. Of special interest, no significant differences were found in the rate of grade 3/4 infections (18% for daily and 26% for weekly protocol, difference -8.2%; 95% confidence interval [CI] -23.2% to 6.9%; P = .28) and the rate of septic deaths (3% for daily and 2% for weekly protocol, difference 1.4%; 95% CI -4.3% to 7.0%; P = .64). In conclusion, HCL treatment with weekly 2-CdA infusions is equally effective but no safer than the standard 5-day 2-CdA protocol.

2-Chlorodeoxyadenosine (2-CdA), a purine analog, has become universally accepted as the agent of choice in treating hairy cell leukemia (HCL). However, few studies have reported long-term outcomes after 2-CdA treatment. Between January 1990 and June 2003, 86 consecutive patients with HCL were treated with a single 7-day course of 2-CdA by continuous infusion at a dose of 0.1 mg/kg per day. Of the 86 patients (mean age: 49 years), 67 patients (79%) achieved a complete remission (CR); 18 patients (21%) achieved a partial remission (PR); and 1 patient's response was unable to be assessed. The progression-free survival (PFS) for initial relapse after 12 years was 54%. At a median follow-up of 9.7 years (range, 0.3-13.8 years), 31 (36%) of 85 patients relapsed. There were 23 relapsed patients treated with a second cycle of 2-CdA; 2 patients were treated with alternative agents; and 6 patients were observed. Of the 23 relapsed patients retreated with 2-CdA, 12 (52%) achieved a CR and 7 (30%) patients achieved a PR (overall response rate: 83%). The overall survival (OS) rate after 12 years was 87%. There were 15 patients (17%) who developed other malignancies. Long-term follow-up of up to 14 years (median: 9.7 years) showed an excellent PFS and OS for HCL patients after 2-CdA treatment.

Patients with systemic mastocytosis (SM) can suffer from disabling symptoms related to mast cell mediator release or mast cell infiltration, requiring mast cell eradication. In the present absence of any curative therapy, a recent case report describing the efficacy of cladribine showed promising results. In a pilot study, the efficacy of cladribine (0.10-0.13 mg/kg in a 2-hour infusion, days 1-5; repeated at 4-8 weeks until 6 cycles) was studied. Ten patients with SM with severe symptoms were treated. Four patients were classified as having indolent or smoldering mastocytosis, 3 as having aggressive systemic mastocytosis, and 3 as having SM with an accompanying hematologic malignancy. Nine patients received 6 courses, 1 patient stopped because of toxicodermia. All responded concerning signs, symptoms, and mast cell parameters (serum tryptase and urinary histamine metabolite excretion), although none achieved a complete remission. Prolonged follow-up is required, as response is ongoing in most cases. One patient relapsed within 11 months and showed a second response. Side effects were mainly related to bone marrow suppression. Single-agent cladribine is an effective and relatively safe treatment for severe systemic mastocytosis. The optimal dose and schedule need to be explored.

Background: To assess the activity and toxicity of 2-chlorodeoxyadenosine (cladribine, CDA) given by subcutaneous bolus injections to patients with hairy cell leukemia (HCL)., Patients and Methods: Sixty-two eligible patients with classic or prolymphocytic HCL (33 non-pretreated patients, 15 patients with relapse after previous treatment, and 14 patients with progressive disease during a treatment other than CDA) were treated with CDA 0.14 mg/kg/day by subcutaneous bolus injections for five consecutive days. Response status was repeatedly assessed according to the Consensus Resolution criteria., Results: Complete and partial remissions were seen in 47 (76%) and 13 (21%) patients, respectively, for a response rate of 97%. All responses were achieved with a single treatment course. Most responses occurred early (i.e. within 10 weeks) after start of CDA therapy, but response quality improved during weeks and even months after treatment completion. The median time to treatment failure for all patients was 38 months. Leukopenia was the main toxicity. Granulocyte nadir (median 0.2 x 10(9)/l) was strongly associated with the incidence of infections (P = 0.0013). Non-specific lymphopenia occurred early after CDA treatment, and normal lymphocytes recovered slowly over several months. No significant associations were found between infections and nadir count of lymphocytes or any lymphocyte subpopulation. No opportunistic infections were observed., Conclusions: One course of CDA given by subcutaneous bolus injections is very effective in HCL. The subcutaneous administration is more convenient for patients and care providers, and has a similar toxicity profile to continuous intravenous infusion. The subcutaneous administration of CDA is a substantial improvement and should be offered to every patient with HCL requiring treatment with CDA.

A reduced-intensity preparative regimen consisting of melphalan and a purine analog was evaluated for allogeneic transplantation in 86 patients who had a variety of hematologic malignancies and were considered poor candidates for conventional myeloablative therapies because of age or comorbidity. Seventy-eight patients received fludarabine 25 mg/m(2) daily for 5 days in combination with melphalan 180 mg/m(2) (n = 66) or 140 mg/m(2) (n = 12). Eight patients received cladribine 12 mg/m(2) continuous infusion for 5 days with melphalan 180 mg/m(2). The median age was 52 years (range, 22-70 years). Disease status at transplantation was either first remission or first chronic phase in 7 patients, untreated first relapse or subsequent remission in 16 patients, and refractory leukemia or transformed chronic myelogenous leukemia in 63 patients. Nonrelapse mortality rates on day 100 were 37.4% for the fludarabine/melphalan combination and 87.5% for the cladribine/melphalan combination. The median percentage of donor cells at 1 month in 75 patients was 100% (range, 0%-100%). The probability of grade 2-4 and 3-4 acute graft-versus-host disease was 0.49 (95% CI, 0.38-0.60) and 0.29 (95% CI, 0.18-0.41), respectively. Disease-free survival at 1 year was 57% for patients in first remission or chronic phase and 49% for patients with untreated first relapse or in a second or later remission. On multivariate analysis the strongest predictor for disease-free survival was a good or intermediate risk category. In summary, fludarabine/melphalan combinations are feasible in older patients with associated comorbidities, and long-term disease control can be achieved with reduced-intensity conditioning in this population.

The efficacy and toxicity of cladribine (2-CdA) + prednisone (P) versus chlorambucil (Chl) + P were compared in previously untreated patients with progressive or symptomatic chronic lymphocytic leukemia (CLL) in a randomized, multicenter prospective trial. Eligible patients were assigned to either 2-CdA 0.12 mg/kg per day in 2-hour infusions and P 30 mg/m(2) per day for 5 consecutive days or Chl 12 mg/m(2) per day and P 30 mg/m(2) per day for 7 consecutive days. Three courses were administered at 28-day intervals or longer if myelosuppression developed. The therapy was finished if complete response (CR) was achieved. Of 229 available patients 126 received 2-CdA+P and 103 received Chl+P as a first-line treatment. CR and overall response rates were significantly higher in the patients treated with 2-CdA+P (47% and 87%, respectively) than in the patients treated with Chl+P (12% and 57%, respectively) (P = .001). Progression-free survival was significantly longer in the 2-CdA-treated group (P = .01), but event-free survival was not statistically different. Thirteen percent of patients were refractory to 2-CdA+P and 43% to Chl+P (P = .001). Drug-induced neutropenia was more frequently observed during 2-CdA+P (23%) than Chl+P therapy (11%) (P = .02), but thrombocytopenia occurred with similar frequency in both groups (36% and 27%, respectively). Infections were seen more frequently in the 2-CdA+P-treated group (56%) than in the Chl+P-treated group (40%; P = .02). Death rates have so far been similar in patients treated with 2-CdA (20%) and with Chl (17%). The probability of overall survival calculated from Kaplan-Meier curves at 24 months was also similar for both groups (78% and 82%, respectively). (Blood. 2000;96:2723-2729)

Background: It is unclear whether the purine analogs fludarabine (Flu) and cladribine (CdA) are non-resistant., Patients and Methods: Sixty patients with relapsed or refractory low-grade NHL were randomly allocated to initial treatment with either Flu 25 mg/m2, or CdA 0.14 mg/kg, each for five consecutive days every four weeks. Upon treatment failure, eligible patients were crossed over to the other study drug., Results: Overall response and CR were 68% and 48% with Flu, and 72% and 38% with CdA, respectively. For responders, actuarial three-year progression-free survival was 58% with Flu and 52% with CdA. Treatment with both drugs was well tolerated, with toxic effects primarily hematological. Two patients (8%) in the Flu group and 15 patients (47%, P = 0.001) in the CdA group were taken off study because of persistent hematological toxicity. After cross over, none of seven refractory patients responded, while eight of nine previously responsive patients achieved second responses., Conclusions: Our study confirms that Flu and CdA have similar response rates and durations. However, further studies are required to optimize the CdA schedule and dosage in order to ameliorate its toxic profile while maintaining antitumor activity. The two drugs appear to be cross-resistant.

Langerhans-cell histiocytosis (LCH) results from the accumulation of tissue histiocytes derived from the same progenitor cells as monocytes. Because cladribine is potently toxic to monocytes, we conducted a phase II trial of cladribine. Cladribine was administered to 13 LCH patients at 0.14 mg/kg per day by 2-hour intravenous infusion for 5 consecutive days, every 4 weeks for a maximum of six courses. Median age was 42 years (range, 19 to 72) and median pretreatment disease duration was 99 months (range, 6 to 252). One patient was untreated, one had received prior prednisone only, one prior radiation only, six prior radiation and chemotherapy, and four prior surgery, radiation, and chemotherapy. Seven patients had cutaneous involvement, six multifocal osseous, six pulmonary, two each with soft tissue and nodal involvement, and four had diabetes insipidus. Of 13 patients, 12 were evaluable for response and all for toxicity. After a median of three courses (range, 1 to 6), seven (58%) patients achieved complete responses (two pathologic and five clinical) and two (17%) patients achieved partial responses; overall response rate, 75%. Median response follow-up duration was 33 months (range, 1 to 65). Seven patients experienced grade 3 to 4 neutropenia. Only one patient had a documented infection, dermatomal herpes zoster. At a median follow-up of 42 months (range, 5 to 76), 12 patients remain alive and one patient has died. Thus, cladribine has major activity in adult LCH and warrants further investigation in both pediatric and adult LCH as a single agent and in combination with other drugs.

Cladribine treatment of hairy cell leukemia (HCL) is complicated by neutropenic fever in 42% of patients despite documented infections being relatively uncommon. We performed a study of priming filgrastim followed by cladribine and then filgrastim again to determine if filgrastim would lead to a reduction of neutropenia and febrile episodes. Thirty-five patients received filgrastim and cladribine and were compared with 105 historic controls treated with cladribine alone. Cladribine was administered at 0.1 mg/kg/d by continuous infusion for 7 days. Filgrastim was administered at 5 micrograms/kg/d subcutaneously on days -3, -2, and -1 and then again after the completion of cladribine until the absolute neutrophil count (ANC) was >/=2 x 10(9)/L on 2 consecutive days (days +8, +9, etc). After filgrastim priming, the median ANC increased from 0.9 x 10(9)/L to 2.26 x 10(9)/L (2.5-fold increase), and after cladribine, the median nadir ANC in the filgrastim-treated group was 0.53 x 10(9)/L compared with 0.29 x 10(9)/L among historic controls (P =. 04). The median number of days to an ANC greater than 1.0 x 10(9)/L was 9 days in the filgrastim-treated group versus 22 days among historic controls (P < 10(-5)). The percentage of febrile patients, number of febrile days, and frequency of admissions for antibiotics were not statistically different in the two groups. Filgrastim regularly increases the ANC in patients with HCL and shortens the duration of severe neutropenia after cladribine. This phase II study, with comparison to historical controls, failed to detect any clinical advantage from the use of filgrastim and cladribine in the treatment of HCL. Accordingly, the routine adjunctive use of filgrastim with cladribine in the treatment of HCL cannot be recommended.

Purpose: Cladribine (2-chlorodeoxyadenosine, 2-CdA) has been reported to be effective in the treatment of low-grade lymphomas. The objective of this multicenter study was to evaluate the activity of cladribine in mantle-cell lymphomas as first-line therapy or in first relapse using an intermittent two-hour infusion of cladribine., Patients and Methods: A total of 47 courses, or an average of four courses per patient, were administered to 12 patients (seven untreated, five relapsed) with 5 mg/m2 cladribine given as an intermittent two-hour infusion over five consecutive days for a maximum of six cycles every four weeks., Results: Cladribine showed activity in patients with mantle-cell lymphomas, achieving a response rate of 58% (95% confidence interval (95% CI): 28%-85%). Myelosuppression was the major toxicity with 17% of grade 3 and 4 neutropenia. Thrombocytopenia was rare with only 2% of grade 3 and 4., Conclusion: These results demonstrate single-agent activity of cladribine in mantle-cell lymphomas using the intermittent two-hour infusion dosage regimen. To further improve treatment results, cladribine should be combined with other agents active in mantle-cell lymphomas.

Hairy cell leukemia is a chronic B-cell disorder that follows an indolent, but progressive course. Cladribine (2-chlorodeoxyadenosine) induces complete remissions in the majority of patients after a single course. We report the long-term outcomes, including response rates and their duration; time-to-treatment failure (TTF) rates; retreatment results; toxicities; and survival rates of patients treated at Scripps Clinic (La Jolla, CA). A total of 358 patients with hairy cell leukemia were treated with cladribine at 0.087 or 0.1 mg/kg body weight per day by continuous intravenous infusion for 7 days. The expected number of second neoplasms was based on the National Cancer Institute's Surveillance Epidemiology and End Results data. Of 349 evaluable patients, 319 (91%) achieved an initial complete response and 22 (7%) a partial response with an overall median duration of response follow-up of 52 months. Ninety patients (26%) had relapsed at a median of 29 months. The TTF rate for all 341 responders was 19% at 48 months, 16% for complete responders, and 54% for partial responders. Of 53 evaluable patients treated with second courses of cladribine at first relapse, 33 (62%) achieved complete responses and 14 (26%) partial responses. Twenty-seven patients (8%) developed second neoplasms (only 1 hematopoietic) with an observed-to-expected ratio of 1.88 (95% confidence interval, 1.24 to 2.74). The overall survival rate was 96% at 48 months. Single courses of cladribine induced long-lasting complete responses in the vast majority of patients. Relapse rates for complete responders were low. Patients who relapse can be successfully retreated with cladribine. Cladribine has high efficacy and a favorable acute and long-term toxicity profile when administered to patients with hairy cell leukemia., (Copyright 1998 by The American Society of Hematology.)

The purpose of this study was to compare the relative risk of second malignancies in a cohort of patients with hairy cell leukemia (HCL) against the normal population. Potential effects of type of treatment and duration of follow-up and the site distribution of cancer were also examined. Between 1976 and 1996, 117 patients were diagnosed with HCL in British Columbia who were referred to the British Columbia Cancer Agency (BCCA) for treatment. All additional malignancies were traced using a provincial population-based cancer registry and follow-up records from the BCCA. There were 90 men and 27 women. Median age at diagnosis was 53 years. The median follow-up time was 68 months. Twenty-three patients underwent primary splenectomy, 65 received interferon alpha, 24 deoxycoformycin, and 67 cladribine (2-chlorodeoxyadenosine). Thirty-six patients had an additional malignancy (30.7%) with a total of 44 tumors. Six patients (5.1%) had two or more malignancies. Twenty-five patients had malignancies diagnosed after HCL (21.3%), three concurrent with HCL (2.6%), and 12 preceding HCL (10.2%). Second tumors (n = 28 tumors) occurred at a median of 40 months after HCL (range, 3 to 167). The relative rate (RR) of second malignancy among men and women was 2.91 (P < .001) and 1.65 (P = .23), respectively, compared with age and secular trend-matched controls. There were eight prostate cancers, nine nonmelanoma skin cancers, two lung cancers, and four gastrointestinal adenocarcinomas. The RR (90% confidence interval [CI]) in the various treatment groups were: splenectomy (RR = 0.21 to 3.81), purine analogues (RR = 0.60 to 5.69), interferon then purine analogues (RR = 1.60 to 4.31), interferon alone (RR = 1. 57 to 8.40). Cancer risk peaked at 2 years after HCL (RR = 4.13) and fell steadily afterwards, reaching a RR of 1.82 at 6 years. Twenty patients died, six due to HCL, 10 due to second malignancies, and four of unrelated causes. HCL patients appear to be inherently prone to malignancies. This appears to be more related to HCL tumor burden than to genetic predisposition or treatment effect. RR tends to fall with time after effective treatment. However, close monitoring for and vigorous prevention of cancer in HCL patients is advisable., (Copyright 1998 by The American Society of Hematology.)

Purpose: To assess long-term survival following cladribine salvage treatment for previously treated patients with chronic lymphocytic leukemia., Patients and Methods: Fifty-two patients aged 39-84 years with previously treated CLL received cladribine 0.12 mg/kg/day in 2-hour infusions for 5 days in monthly courses. Two-thirds were refractory to previous therapy, and 8 had prior fludarabine., Results: Sixteen (31%) patients achieved complete response (CR) and 14 (27%) partial remission (PR) according to consensus criteria. Response correlated with clinical stage, number of previous treatment regimes, blood lymphocyte count, and lymphocyte halflife following the first cladribine course. Toxicity included pneumonia (n = 9), herpes zoster (n = 7), and septicemia (n = 2). Four patients in CR underwent high-dose chemotherapy with autologous blood stem cell support, and 2 remain in CR 48 and 60 months from start of cladribine, and 2 had relapse at 42 and 48 months, respectively. Median progression-free survival (Kaplan-Meier analysis) for CR patients was 23 months from start of cladribine treatment, and for PR patients 16 months. The projected overall survival was 80% at 3 years for CR patients, and the median survival 28 months for PR patients and 4 months for non-responding patients., Conclusions: Our previous finding of durable CRs from cladribine in advanced CLL is thus confirmed in a larger patient material, and follow-up indicate that long-term survival may be achieved.

We investigated the efficacy of 2-chlorodeoxyadenosine (2-CdA) therapy in patients with mycosis fungoides (MF) and the Sezary syndrome (SS). Between February 1991 and November 1993, 21 patients with relapsed or refractory MF/SS were treated with 2-CdA. 2-CdA was administered by continuous intravenous infusion at a dose of 0.1 mg/kg/d for 7 days initially (13 patients), but was subsequently reduced to 5 days (nine patients) due to hematologic toxicity. All patients had failed to respond to at least one prior treatment for MF/SS (median number of total prior therapies, five; median number of systemic prior therapies, three) and had an Eastern Cooperative Oncology Group performance status of two or better. Cycles were administered at 28-day intervals. Assessable patients received at least 5 days of 2-CdA. Fourteen patients received more than one cycle of 2-CdA. An overall response rate of 28% was achieved. Three patients (14%) had a complete response with a median duration of 4.5 months (range, 2.5 to 16). Three (14%) had a partial response with a median duration of 2 months (range, 2 to 4). Fifteen patients (72%) had no response. The most significant toxicities encountered were bone marrow suppression (62% of patients) and infectious complications (62% of patients). Thirty-eight percent of patients experienced no toxicity from 2-CdA. 2-CdA has activity as a single agent in patients with previously treated relapsed MF/SS. Studies in less heavily pretreated individuals with 2-CdA alone or in combination will be undertaken.

Background: Neutropenic fever is the commonest complication of cladribine therapy for hairy-cell leukemia (HCL), leading to a 3% mortality rate. Our aim was to identify predictive factors and evaluate the effects of concomitant granulocyte-macrophage colony-stimulating factor (GM-CSF)., Patients and Methods: We studied 102 patients with active HCL given cladribine for 7 days. Pretreatment parameters predicting neutropenic fever were analysed. Twelve patients at high risk for febrile complications also received 400 micrograms GM-CSF per day on days 1 through 21., Results: Pretreatment anemia, hypocholesterolemia, bone marrow differential with a high percentage of hairy cells and a low percentage of myelopoietic cells, low albumin, and high C-reactive protein predicted neutropenic fever. The addition of GM-CSF did not improve the kinetics of recovery for neutrophils, hemoglobin or platelets, as compared to matched control patients. However, GM-CSF significantly reduced cladribine-induced lymphopenia, but not the incidence of neutropenic fever., Conclusion: Factors predicting febrile neutropenia were identified. GM-CSF protected from cladribine lymphotoxicity but did not improve neutropenia or febrile episodes.

Background: Few effective treatments are available for patients with Waldenstrom's macroglobulinemia that is resistant to standard therapies. We assessed the activity of 2-chlorodeoxyadenosine (2CdA) in patients with resistant macroglobulinemia in order to identify those most likely to benefit., Patients and Methods: 2-chlorodeoxyadenosine was given to 46 consecutive patients with Waldenstrom's macroglobulinemia resistant to a combination of an alkylating agent and a glucocorticoid. Two courses were administered to outpatients at a dose of 0.1 mg/kg body weight per day for a 7-day continuous infusion using a portable pump through a central venous catheter. Responding patients were followed without further therapy., Results: Twenty of 46 patients responded to 2CdA therapy (43%; 95 CI; 29 to 60%) with a significantly higher frequency of benefit among patients with disease relapsing off therapy (78%) or with primary resistant disease within the first year (57%) than in those with later phases of disease (22%). The median survival after treatment was 28 months and the median progression-free survival of responding patients was 12 months. The longest survival was measured in patients with primary refractory disease (projected median 36 months) and the shortest in those with disease in refractory relapse (median 13 months)., Conclusion: 2-Chlorodeoxyadenosine is active against macroglobulinemic lymphoma resistant to standard regimens and most effective in patients with disease relapsing off treatment or during the first year of primary refractory disease. Little benefit was observed among patients with later phases of resistant disease who should receive alternative treatments.

Mature T-cell lymphoproliferative disorders comprise a heterogenous group of diseases for which there is no standard therapy. These disorders are uncommon, and are usually treated similarly to their B-cell counterparts, but with less success. Nucleoside analogues have proven effective in indolent B-cell disorders but have been less well explored in T-cell malignancies. We treated 22 patients with mature T-cell lymphoproliferative diseases with 2-chlorodeoxyadenosine (2-CDA) administered as a continuous infusion at a daily dose of 4 mg/m2 over 7 days. Nineteen of the patients had received prior therapy with a median number of prior regimens of three. Eleven patients had leukemia or large granular lymphocytosis, eight patients had mycosis fungoides, and three had T-cell lymphoma. Nine patients (41%) responded to 2-CDA. Four of the patients had responses that were complete remissions, and three of these four patients remain in remission at 23, 24, and 23 months. The only important toxic effects were fever or infection, seen during 38% of courses. In conclusion, 2-CDA appears to be an effective therapy in T-cell lymphoproliferative disorders and deserves wider evaluation in this subset of patients.

Chronic progressive multiple sclerosis (MS) is a severely disabling demyelinating disease in which autoimmune processes seem to have a major role. The nucleoside drug cladribine is a potent lympholytic agent with few side-effects. We have studied its efficacy and safety in a randomised double-blind trial. 51 patients (48 entered as matched pairs) received four monthly courses of 0.7 mg/kg cladribine or placebo (saline) given through a surgically implanted central line. Neurologists with no knowledge of which medication the patient was receiving examined the patients monthly and noted two rating scale scores (Kurtzke and Scripps). Cerebrospinal fluid and brain magnetic resonance imaging (MRI) examinations were done at 6 and 12 months. Average neurological scores, demyelinated volumes on MRI, and concentrations of oligoclonal bands in cerebrospinal fluid were stable or improved in the patients receiving cladrabine but continued to deteriorate in patients on placebo. Mean paired (placebo minus matched cladribine) differences at 12 months relative to baseline were 1.0 (SE 0.4) for the Kurtzke scores, -13.9 (2.3) for the Scripps scores, 4.57 (1.17) mL for demyelinated volumes, and 7.3 (3.3) arbitrary units for concentrations of oligoclonal bands. Cladribine was generally well tolerated and clinically significant toxicity occurred in only 1 patient, in whom severe marrow suppression developed with complete recovery after several months. 1 patient died of newly acquired hepatitis B, an event unlikely to be related to cladribine. We conclude that the immunosuppressive drug cladribine influences favourably the course of chronic progressive MS.

Background: Fludarabine monophosphate and 2Chlorodeoxyadenosine are nucleoside analogues with activity against Waldenström macroglobulinemia. However, it is not clear whether prior exposure to one analogue precludes response to the other compound., Patients and Methods: Fourteen patients with Waldenström's macroglobulinemia and prior exposure to fludarabine were treated with two courses of 2chlorodeoxyadenosine., Results: Three out of four patients that had previously responded to fludarabine and were relapsing from unmaintained remission, achieved a partial response with 2chlorodeoxyadenosine therapy. However, only one out of 10 patients with disease resistant to fludarabine responded to 2chlorodeoxyadenosine., Conclusions: 2chlorodeoxyadenosine may be effective in patients with Waldenström macroglobulinemia sensitive to fludarabine. However, this compound has limited activity for patients with disease resistant to fludarabine.

Background: 2-chlorodeoxyadenosine (2-CDA) is a new purine analogue which has been shown to be highly active in lymphoproliferative disorders. In this clinical trial we assessed 2-CDA toxicity and response rate in patients with various haematological malignancies who were heavily pre-treated and mostly refractory to standard treatment regimens., Patients and Methods: Twenty-two refractory patients, 51 relapsing after standard chemotherapy and seven non-pre-treated patients were treated in a non-randomized prospective phase II multicentric study. Their median age was 54 years (range 18-84) and 56 of them were male. Thirty-one had non-Hodgkin's lymphoma (NHL), 11 chronic lymphocytic leukaemia (CLL), 1 prolymphocytic leukaemia (PLL), 13 hairy-cell leukaemia (HCL), 2 mycosis fungoides (MF), 3 multiple myeloma, 7 acute myeloblastic leukaemia (AML), 2 acute lymphoblastic leukaemia (ALL), 6 chronic myeloid leukaemia (CML) in blast crisis, 2 Hodgkin's disease, 1 Waldenström's macroglobulinemia and 1 Langerhans histiocytosis. 2-CDA 0.1 mg/kg/day was given as a continuous intravenous infusion for 7 days and recycled every 4 weeks., Results: One hundred thirty-two courses of 2-CDA were administered to 80 patients, 76 of whom were evaluable for response. A) Toxicity: Myelosuppression: Neutropenia to over 50% of initial value occurred in 46% of patients, thrombocytopenia in 8%, and lymphopenia < 0.5 x 10(9)/l was seen in 41%. Infections occurred in 34/80 patients (43%). The risk of severe infections (WHO grades 3-4) correlated with increasing number of years after first diagnosis (p = 0.01) and low lymphocyte counts on days 1 and/or 14 (p = 0.04); 21 infections were opportunistic. B) Response: 70% patients with lymphoproliferative disorders of low malignancy attained complete or partial response (low-grade NHL 12/16, CLL + PLL 9/12, HCL 13/13, MF 2/2, myeloma 0/3); in patients with AML, ALL, CML in myeloid (n = 4) or lymphoid (n = 2) blast crisis and high-grade lymphoma responses were seen in only 11%. Response was inversely related to the number of pretreatments (p = 0.045). In responding NHL patients the mean lymphocyte count on day 14 of cycle 1 was significantly lower (median 0.6 x 10(9)/l) than that of non-responders (1.2 x 10(9)/l, p = 0.04)., Conclusion: 2-CDA had a high activity even in heavily pretreated and refractory patients with low-grade lymphoproliferative disorders. In contrast to previously published studies, infections, mainly opportunistic, were a serious side effect in our study. In patients with severe lymphopenia at therapy initiation, the value of prophylactic anti-infective treatment should be studied.