Success in the treatment of patients with hairy cell leukemia (HCL) over the last several decades is largely due to the high efficacy of the nucleoside analogs, cladribine and pentostatin. However, the relapse-free survival curves have not shown a plateau and many patients treated with these agents will eventually relapse. Although better understanding of the pathogenic mechanisms in HCL have led to effective and novel options for the treatment of relapse, long term durability of the responses obtained with these agents still remains unclear. Combination of nucleoside analogs with monoclonal antibodies such as rituximab has been shown to be safe and effective and has the potential to supersede the nucleoside analogs as the frontline strategy. Such chemo-immunotherapy approaches are under further investigation and will have to be assessed with socioeconomic considerations in mind. Other novel monoclonal antibodies, approved for the treatment of other lymphoid neoplasms, may also be considered for future studies of chemo-immunotherapy.

Since 2006 when we last reviewed the literature concerning the use of purine analogues in hairy cell leukaemia (HCL), results from several new and updated series have been published. Here we examine these reports and consider their implications for patient management. The two purine analogues pentostatin and cladribine remain the first-line treatments of choice for all patients with HCL. Although they have not been compared in randomised trials, they appear to be equally effective. A complete response is important for the long-term outcome and we look at how best this can be achieved. Evidence is emerging which supports the use of either purine analogue plus an anti-CD20 monoclonal antibody after relapse, though questions remain concerning the scheduling of the monoclonal antibody. Patients refractory to the purine analogues may require alternative agents.

While the renal complications of plasma cell dyscrasia have been well-described, most information in patients with chronic lymphocytic leukemia and monoclonal B-cell lymphocytosis is derived from case reports. This is a retrospective analysis of patients with chronic lymphocytic leukemia or monoclonal B-cell lymphocytosis who underwent kidney biopsy for renal insufficiency and/or nephrotic syndrome. Between January 1995 and June 2014, 49 of 4,024 (1.2%) patients with chronic lymphocytic leukemia (n=44) or monoclonal B-cell lymphocytosis (n=5) had a renal biopsy: 34 (69%) for renal insufficiency and 15 (31%) for nephrotic syndrome. The most common findings on biopsy were: membranoproliferative glomerulonephritis (n=10, 20%), chronic lymphocytic leukemia interstitial infiltration as primary etiology (n=6, 12%), thrombotic microangiopathy (n=6, 12%), and minimal change disease (n=5, 10%). All five membranoproliferative glomerulonephritis patients treated with rituximab, cyclophosphamide and prednisone-based regimens had recovery of renal function compared to 0/3 patients treated with rituximab with or without steroids. Chronic lymphocytic leukemia infiltration as the primary cause of renal abnormalities was typically observed in relapsed/refractory patients (4/6). Thrombotic microangiopathy primarily occurred as a treatment-related toxicity of pentostatin (4/6 cases), and resolved with drug discontinuation. All cases of minimal change disease resolved with immunosuppressive agents only. Renal biopsy plays an important role in the management of patients with chronic lymphocytic leukemia or monoclonal B-cell lymphocytosis who develop renal failure and/or nephrotic syndrome.

Cordyceps sinensis, a fungus that parasitizes on the larva of Lepidoptera, has been used as a valued traditional Chinese medicine. We investigated the effects of water extracts of Cordyceps sinensis (WECS), and particularly focused on its anticancer and antimetastatic actions. Based on in vitro studies, we report that WECS showed an anticancer action, and this action was antagonized by an adenosine A3 receptor antagonist. Moreover, this anticancer action of WECS was promoted by an adenosine deaminase inhibitor. These results suggest that one of the components of WECS with an anticancer action might be an adenosine or its derivatives. Therefore, we focused on cordycepin (3'-deoxyadenosine) as one of the active ingredients of WECS. According to our experiments, cordycepin showed an anticancer effect through the stimulation of adenosine A3 receptor, followed by glycogen synthase kinase (GSK)-3β activation and cyclin D1 suppression. Cordycepin also showed an antimetastatic action through inhibiting platelet aggregation induced by cancer cells and suppressing the invasiveness of cancer cells via inhibiting the activity of matrix metalloproteinase (MMP)-2 and MMP-9, and accelerating the secretion of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 from cancer cells. In conclusion, cordycepin, an active component of WECS, might be a candidate anticancer and antimetastatic agent.

Corticosteroid-refractory (SR) acute graft-versus-host disease (aGVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Multiple agents have been evaluated in this setting, but the benefit of pentostatin has not been described well. We report a single-center experience of pentostatin salvage therapy for SR aGVHD. Fifteen patients received pentostatin for SR aGVHD from March 2005 till March 2010 after failure to respond to methylprednisolone ≥ 2 mg/kg/d for at least seven d. All patients had grade III-IV aGVHD prior to pentostatin therapy. Thirteen (87%), 10 (67%), and six (40%) patients had gastrointestinal (GI), skin, and liver involvement of aGVHD, respectively. Pentostatin was given at a median of 33 d after steroid therapy initiation. The dose of pentostatin was 1.4 mg/m(2) daily for three d, repeated every two wk. Eight (53%) patients also received additional therapies. Complete responses were noted in two patients (both in skin). However, one patient relapsed and did not respond to additional salvage treatment. Partial responses were seen in three patients. Fourteen died of GVHD-related causes. This study suggested that pentostatin is of limited benefit in the treatment for SR grade III-IV aGVHD.

Abstract Purine analogs are highly effective in hairy cell leukemia (HCL) with response rates of 85%, but with many late relapses. We have retrospectively reviewed the clinical data from 107 patients treated with pentostatin (n = 27) or cladribine (n = 80), to investigate the long-term efficacy and to identify factors associated with the treatment-free interval (TFI). Complete remission and minimal residual disease (MRD) rates were similar in both groups. Median TFI was shorter (95 vs. 144 months) in the pentostatin group, although the difference was not significant (p = 0.476). MRD+ patients had shorter TFI than MRD- patients (97 months vs. not reached, p < 0.049). A hemoglobin level < 10 g/dL predicted for a shorter TFI only in the pentostatin group. Quality of response and number of hairy cells in the bone marrow are independent risk factors of treatment failure. The relationship between MRD+ and shorter TFI makes it of special interest to explore consolidation therapy with monoclonal antibodies to achieve durable responses.

Hematopoietic-cell-transplantation-specific-comorbidity-index (HCT-CI) has been reported as a predictor of survival in allogeneic-transplant recipients; however its validity has recently been challenged. We evaluated the association of HCT-CI with survival of transplant recipients who underwent reduced-intensity-conditioning (RIC) with photopheresis, pentostatin, and total-body-irradiation. Median age of 103 patients selected was 55 years. Most patients (58.3%) had high (≥ 3) HCT-CI. Median OS was 298 days. Age, disease-type, disease-status, HCT-CI correlated with survival on bivariate analysis. On multivariate analysis, only HCT-CI was significantly associated with OS (low HCT-CI HR=0.29, CI 0.091-0.886; intermediate HCT-CI HR=0.41, CI 0.226-0.752). Our findings suggest HCT-CI as an independent predictor of survival in the setting of RIC transplants.

One limitation of reduced-intensity preparative regimens is potential for graft failure. We have developed a regimen that targets CD4(+) lymphodepletion to ensure early and durable engraftment. The primary endpoint was achievement of ≥50% CD3(+) donor chimerism by day +28. Forty-two patients (median age, 53 years; range, 29 to 73 years) received pentostatin 4 mg/m(2) i.v. on days -28, -21, and -14 when the CD4(+) cell count was >100 cells/μL and on days -4 and -3 regardless of CD4(+) level. Rituximab 375 mg/m(2) was administered to patients with CD20(+) malignancies on days -21, -14, -7, +1, and +8. Busulfan 200 mg/m(2) i.v. was administered on days -4 and -2 at a dose to target a cumulative AUC dose of 16,000 (±10%) μmol·min/L. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus plus methotrexate in 86% of patients. Donors were matched-related (47%), matched unrelated (43%), or mismatched unrelated (10%). Chronic lymphocytic leukemia (45%) and follicular non-Hodgkin lymphoma (14%) were the most common diagnoses. Disease status at initiation of the preparative regimen was complete remission in 22%, partial response in 55%, and stable/progression in 24%. The median percent CD4(+) cell count decrease from baseline (day -28) was 52% to day -21, 66% to day -14, 62% to day -7, and 91% to day 0. At day +28, all 42 patients (100%) had ≥50% CD3(+) donor chimerism. No patient experienced graft failure. Overall response rate was 82% (complete remisson, 67%). The day +100 cumulative incidence of grade II-IV acute GVHD was 59% (grade III-IV acute GVHD, 19%), and the 2 year cumulative incidence of chronic GVHD was 69% (moderate/severe, 58%). Nonrelapse mortality was 2% at day +100 and 17% at 2 years. Two-year PFS was 55%, and OS was 68%. This regimen ensures durable engraftment, is effective against persistent disease, and results in relatively low mortality from causes other than relapse.

Hairy cell leukemia (HCL) is a rare chronic lymphoproliferative disorder characterized by circulating B cells with cytoplasmic projections, pancytopenia, splenomegaly, and a typical flow cytometry pattern. Recently, the BRAF V600E mutation was uniformly identified in one HCL series, which may provide insights into the pathogenic mechanisms. The disease course is usually indolent but inexorably progressive. Patients require treatment when they have significant cytopenia or occasionally recurrent infections from immunocompromise. In the mid-1980s, interferon replaced splenectomy as the initial treatment. A few years later, 2 purine nucleoside analogs, cladribine and pentostatin, showed promising activity in HCL. Complete response rates approached 95% with cladribine given as a single 7-day intravenous infusion. Newer methods of cladribine administration and modified dosing schedules have since been studied. Pentostatin response rates are comparable. We generally prefer cladribine because of its ease of administration, single infusion schema, and favorable toxicity profile. Since the introduction of these drugs, which have never been randomly compared, long-term follow-up studies have confirmed impressive and durable response durations. However, roughly 40% of patients with HCL eventually relapse. In this setting, patients can be re-treated with purine analogs. Rituximab also has a reasonable response rate in relapsed HCL; it can be given as a single agent sequentially after purine nucleosides or concurrently. Immunotoxins have robust responses but remain in development. Targeting the BRAF pathway will be an exciting future area of research. Many patients have minimal residual disease after initial treatment, but the clinical significance of this remains unknown.

Hairy cell leukemia (HCL) was once considered an untreatable form of chronic lymphoid malignancy. Based upon the recognition of the importance of adenosine deaminase to the normal B cell survival and proliferation, a hypothesis was developed that temporary inhibition of this enzyme might be therapeutically successful in treating chronic B cell leukemias. Pentostatin was initially explored in patients with refractory chronic lymphocytic leukemia (CLL). Both pentostatin and cladribine, purine nucleoside analogs, have been utilized to successfully treat HCL. The high degree of complete and durable remission observed with either agent resulted in many believing that the treatment of this rare disease had been fully optimized. However, a considerable number of patients will relapse. While tremendous progress has been made in initial management, the issues related to optimal therapy, timing of initiation of treatment, and discovery of novel agents that may be effective in those who have relapsed are important. Investigational agents currently being explored in chronic lymphocytic leukemia may also have benefit for those patients who have relapsed or are resistant to therapy of hairy cell leukemia. Many important questions remain (e.g. importance of minimal residual disease) and will require international collaboration to fully address these unanswered questions. The Hairy Cell Leukemia Consortium was established to address these unanswered questions.

Over the past 25 years we have collected data at our institution from 242 patients with hairy cell leukemia (HCL), treated with pentostatin (n = 188) or cladribine (n = 54), with a median follow-up of 16 years. From this we have been able to conclude that there is no significant difference in outcome between the two agents either at first or subsequent lines of therapy. Overall, the complete response (CR) rate is 81% and the median disease-free survival (DFS) is 16 years. After relapse or non-response patients can be successfully retreated with pentostatin or cladribine achieving a lower rate of CRs with each line of therapy, although these remain equally durable. Complete response and pretreatment counts of hemoglobin >10 g/dL together with platelets >100 × 10(9)/L are associated with the longest DFS. Importantly, for patients achieving a CR the DFS is five times as long as for those achieving a partial response (PR). Patients still in CR at 5 years have only a 25% risk of relapse by 15 years. Outcomes for patients with recurrent disease have improved with the addition of rituximab to either purine analog. Overall, only eight patients have died of HCL-related causes. Patients with HCL who achieve a CR can expect a normal lifespan.

The purine analogs pentostatin and cladribine are effective treatments for hairy cell leukemia (HCL). However, alternative treatments are needed for patients with recurrent disease. We reviewed retrospectively data from 18 patients who were retreated with either pentostatin (n = 12) or cladribine (n = 6) in combination with rituximab, after 1-6 (median 2) previous treatments with either purine analog as a single agent. All 18 patients responded to therapy, with a complete response (CR) rate of 89%. This compared favorably with CR rates of 68% after second-line therapy and 47% after third-line therapy in 88 patients retreated one or more times with a purine analog alone. Toxicity with the combination treatment was minimal. At a median follow-up of 36 months (range 5-83 months) all 16 complete responders remained in CR, while one partial responder developed recurrent disease at 10 months. The estimated recurrence rate at 3 years was 7%. This compares with 21% after second-line therapy and 42% after third-line therapy in the 88 patients retreated with a purine analog alone. Furthermore, it was a marked improvement on the 55% recurrence at 3 years previously seen in these same 18 patients after their own first-line treatment with single-agent pentostatin or cladribine (p = 0.006). The combination of a purine analog with rituximab was safe and effective for patients with recurrent HCL. The results suggest an added benefit compared with single-agent purine analog therapy.

Pentostatin (2'-deoxycoformycin; dCF) and cladribine (2-chlorodeoxyadenosine; CdA) are highly effective agents for the treatment of hairy cell leukemia. Although their precise mechanisms of action in this disease are still unknown, a number of mechanisms have been postulated. dCF is a potent inhibitor of adenosine deaminase (ADA), and treatment results in the accumulation of deoxyadenosine (dAdo) and adenosine (Ado) in the plasma. dAdo is phosphorylated by deoxycytidine kinase in lymphocytes to deoxyadenosine monophosphate (dAMP), which is subsequently converted to deoxyadenosine triphosphate (dATP). CdA is the chlorinated derivative of deoxyadenosine, is resistant to degradation by ADA, and accumulates in lymphocytes as CdATP. Both dATP and CdATP cause an initial accumulation of DNA strand breaks in lymphocytes and this results in the activation of p53, the release of cytochrome c from mitochondria, and apoptosis. CdA has several unique mechanisms of action over dAdo and these include the incorportation of CdATP into DNA, the inhibition of DNA polymerase β, and the phosphorylation of CdA to CdATP by deoxyguanosine kinase in mitochondria. These additional modes of action produce further DNA breaks in CdA-treated cells and explain the more potent activity of CdA compared to dCF and the greater myelosuppression with this agent. The cells die by apoptosis, but the DNA strand breaks also cause the activation of poly(ADP-ribose) polymerase (PARP), with resultant cellular depletion of nicotinamide adenine dinucleotide (NAD) and ATP. The induction of necrosis by PARP activation may explain the activity of these analogs in some patients with p53 mutations.

Hepatosplenic T cell lymphoma (HSTL) is a rare condition usually with an aggressive course and a poor prognosis even after extensive treatment. We describe here a patient who presented with hemophagocytosis. The lymphoma had unusual phenotypic features, an indolent course and responded to 20-deoxycoformycin therapy as a single agent. We suggest that this therapy be used in further cases as part of the treatment strategy.

BACKGROUND: The combination of pentostatin (P), cyclophosphamide (C), and rituximab (R) achieved an overall response (OR) rate >90%, with >40% complete responses (CRs) in patients with untreated chronic lymphocytic leukemia (CLL).
METHODS: To evaluate whether the tolerability of this regimen could be enhanced without sacrificing efficacy, a phase 2 trial was conducted of P and R without C, using a higher P dose (4 mg/m(2)). Among the 33 patients enrolled, 82% were male, the median age was 65 years (9 patients were aged >or=70 years), and 64% were classified as having Rai stage III to IV disease.
RESULTS: The OR rate was 76%, with 9 CRs (27%), 5 nodular partial responses, and 11 partial responses (PRs) reported. At the time of last follow-up, 29 of 33 patients were still alive at a median follow-up of 14 months (range, 1-34.8 months). Four (12%) patients experienced grade 3 or higher hematologic toxicity, and 5 (15%) experienced grade 3 or higher nonhematologic toxicity. Comparison of this trial with the previous PCR trial demonstrated that patients treated with PCR had a higher OR rate (91% vs 76%) and CR rate (41% vs 27%) compared with patients treated with PR. The median treatment-free survival for all accrued patients was notably longer in patients treated with PCR compared with PR (30 months vs 16 months).
CONCLUSIONS: The findings of the current study suggest that increasing the dose of the purine nucleoside analogue does not eliminate the need for cyclophosphamide in chemoimmunotherapy for the treatment of CLL.

OBJECTIVE: This article assesses the cost-effectiveness of pentostatin compared with cladribine in the management of hairy cell leukemia (HCL) in the United Kingdom.
METHODS: A systematic literature search for papers on HCL was performed using MEDLINE, EMBASE, Current Contents, NHS Economic Evaluation Database, and the Cochrane computerized database. Search terms were HCL plus 1 of the following: incidence, prevalence, epidemiology, cladribine, interferon, pentostatin, rituximab, splenectomy, utility, quality of life, cost-effectiveness, cost-utility, resource utilization, economic, or cost. Published clinical outcomes and estimates of health care resource use obtained from 10 consultant hematologists across the United Kingdom were used to construct a 5-year Markov model depicting the current management of HCL in the United Kingdom. Utilities for health states in the model were obtained from the general public using standard gamble, time tradeoff, and visual analog scale techniques. The model was used to consider the decision by a clinician to initially treat an HCL patient with either pentostatin or cladribine and to estimate the relative cost-effectiveness of pentostatin over 5 years (at 2007/2008 prices) from the perspective of the UK's National Health Service (NHS).
RESULTS: According to the model, 64% of all pentostatin-treated patients are expected to be in relapse-free remission at 5 years compared with 49% of cladribine-treated patients (P = 0.04). Repeat treatment of initial partial responders, nonresponders, and those who relapse during the 5 years is expected to result in complete remission in 92% of pentostatintreated patients and 90% of cladribine-treated patients at 5 years. Using pentostatin instead of cladribine is expected to lead to a minimal cost increase (from 21,325 pounds to 21,609 pounds) and an improvement in health status (from 3.64 to 3.77 quality-adjusted life-years [QALYs]) over 5 years. Hence, the cost per QALY gained from using pentostatin is expected to be 5000 pounds. Moreover, pentostatin has a 0.90 probability of being cost-effective for a threshold of 20,000 pounds per QALY. Accordingly, using pentostatin as a first-line treatment for patients with HCL is an effective use of NHS resources.
CONCLUSION: Based on current practice, this model predicts that pentostatin is a cost-effective treatment compared with cladribine in the management of HCL from the perspective of the UK's NHS.

IMPORTANCE OF THE FIELD: One of the feared events encountered in hairy cell leukemia (HCL) survivors is the subsequent development of a malignant neoplasm. The increased incidence of second cancers in HCL has been documented in large epidemiologic studies conducted in various locations on the globe.
AREAS COVERED IN THIS REVIEW: The authors explore the current clinico-epidemiologic evidence, as well as the immune alterations, that link HCL and its therapies to the development of second cancers. Most relevant publications have been identified through the PubMed/Medline database search.
WHAT THE READER WILL GAIN: Although HCL patients could develop both HCL and secondary malignancies because of a shared genetic predisposition, a common environmental carcinogen, or not yet identified infectious agents, multiple immune defects documented in HCL might play an important role in second carcinogenesis. Furthermore, the 'gold standards' of HCL therapy - cladribine and pentostatin - are associated with profound and prolonged suppression of the CD4(+) T-lymphocyte counts, often in excess of 2 - 3 years. And while there is no clear-cut evidence that pentostatin or interferon-alpha play an established role in generation of an excess of second cancers in HCL, the safety of cladribine, the preferred agent by a majority of clinicians worldwide, in this regard is a still largely unsettled issue.
TAKE-HOME MESSAGE: Therefore, it remains to be seen if the immune deficiencies induced by the HCL therapies and their consequences can be offset by the benefit conferred by controlling the leukemic process.

There is no standard therapy for steroid-refractory chronic graft-versus-host disease (GVHD). This problem is particularly daunting in children with chronic GVHD, whereby the effects of the disease and its treatment may impair normal growth and development. Children are also particularly vulnerable to failure and/or toxicity of therapy; for example, joint contractures or joint damage may result in life-long disability. The Pediatric Blood and Marrow Transplant Consortium performed a phase 2 trial of pentostatin for steroid-refractory chronic GVHD in 51 children (median age, 9.8 years) from 24 institutions. Overall response was 53% (95% confidence interval, 40%-64%), with a response of 59% (95% confidence interval, 42%-75%) in sclerosis. Thirteen subjects (25%) had toxicity requiring them to stop pentostatin. The drug had a significant steroid-sparing effect in those that responded. A trend was also observed toward increased survival at 3 years in responders versus nonresponders (69% vs 50%; P = .06). The intravenous administration of the drug ensures compliance in a patient group in which oral therapy is difficult to monitor. Pentostatin has activity in refractory chronic GVHD in children, and future studies, including treatment of children newly diagnosed with high-risk chronic GVHD, are warranted. The trial was registered at www.Clinicaltrials.gov as #NCT00144430.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is a disease that typically afflicts older individuals with a median age of diagnosis in the eighth decade of life for which treatments available now are not curative. Although purine analogue based combinations produce complete responses (CRs) in many patients, the use of these combinations has been limited by toxicity including myelosuppression and an increased risk of infectious complications.
OBJECTIVE: To identify the role of pentostatin, a specific inhibitor of adenosine deaminase (ADA), in the treatment of CLL. We compare pentostatin to other purine analogues, most notably fludarabine, with regard to safety and efficacy. Finally, we review the use of pentostatin in other diseases.
METHODS: The scope of this review encompasses the history of treatment for CLL as well as the genesis of modern combination chemoimmunotherapy and the advantages of pentostatin within such a treatment program.
RESULTS: Combination therapy with pentostatin seems to provide response frequencies comparable to fludarabine based combinations but with less toxicity and with greater ease of administration.

We report a 25-year-old woman with T-cell large granular lymphocytic leukaemia presenting with severe neutropenia, anaemia and recurrent infections with a chronic disease course. Immunophenotyping showed an expansion of CD3+, TCRgamma delta+, CD4-, CD5+, CD7+, CD8+, CD57+ large granular lymphocytes. Clonality was demonstrated with T-gamma polymerase chain reaction analysis which revealed clonal rearrangement of the TCRgamma chain gene. Cyclosporine, granulocyte colony-stimulating factor, methothrexate and a combination of cyclophosphamide, vincristine and prednisolone failed to correct the neutropenia and the anaemia. Finally, treatment with 2-deoxycoformycin resulted in both clinical and haemotological complete responses, despite molecular evidence of the persistence of the abnormal T-cell clone.

PURPOSE: Therapy for patients with chronic graft-versus-host disease (cGVHD) is based on prolonged immunosuppression with corticosteroids. There is no standard therapy for patients whose cGVHD does not resolve with corticosteroid treatment. Pentostatin, a potent inhibitor of adenosine deaminase, has activity in acute GVHD. We examined the toxicity and efficacy of pentostatin in a prospective phase II trial in corticosteroid-refractory cGVHD.
PATIENTS AND METHODS: Patients of any age were eligible. Patients received pentostatin 4 mg/m2 intravenously every 2 weeks for 12 doses, and continued therapy as long as benefit was documented. Corticosteroid taper was begun after three doses of pentostatin. Responses were graded in real time in the skin, mouth, and liver using objective response criteria.
RESULTS: Fifty-eight heavily pretreated (median, four prior regimens) patients (median age, 33 years) were enrolled. Results are shown as an intent-to-treat analysis. Of the 58 patients, a total of 32 (55%; 95% CI, 42% to 68%) had an objective response, as evaluated by use of a new grading scale. Infection was the most significant toxicity, with 11 grade 3 to 4 infectious events. The survival at 1 and 2 years was 78% (95% CI, 64% to 86%) and 70% (95% CI, 57% to 80%), with cGVHD with/without infection accounting for the majority of deaths.
CONCLUSION: Pentostatin has immunosuppressive effects that are currently being explored further for treatment of cGVHD.

We conducted a multicenter, community-based phase II trial of PCR biochemotherapy (pentostatin 4 mg/m2, cyclophosphamide 600 mg/m2, and rituximab 375 mg/m2) every 3 weeks for up to 6 cycles in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). The study was stopped after enrolling 24 patients because of diminished investigator interest after 8 patients discontinued treatment because of adverse events, and 5 others died during treatment. The median age of patients was 69 years; 11 patients were over age 70, and 71% had Rai stage III or IV disease. The response rate among the 17 evaluable patients who completed 3 cycles of therapy was 58% (35%-81%, 95% confidence interval), with 2 complete responders (both greater than 70 years of age) and 7 partial responders. No patients developed progressive disease while receiving PCR. This is the first report of a trial in CLL utilizing a combination of purine analog, alkylator, and rituximab, in which most patients were older than 65 years and had high-risk disease. PCR is active in CLL/SLL, but appears to be less active and associated with more complications in the community setting, compared to trials with younger, lower risk patients who travel to academic referral centers for treatment.

Pentostatin is an adenosine deaminase inhibitor used in the treatment of hairy cell leukemia and T-cell lymphomas. A 27-year-old man with refractory cutaneous T-cell lymphoma developed severe hyponatremia 3 days after completing his first cycle of pentostatin therapy. Shortly after hospital admission, he became disoriented and was admitted to the medical intensive care unit and treated with a combination of hypertonic saline, intravenous diuretics, and fluid restriction to reestablish normal sodium homeostasis. The mechanism by which pentostatin may have induced hyponatremia in this patient is unknown; clinical and laboratory findings represented both extrarenal sodium loss and syndrome of inappropriate antidiuretic hormone. Clinicians should be aware of the possible development of life-threatening symptomatic hyponatremia in patients receiving pentostatin.

Building on the prior work of use of pentostatin in chronic lymphocytic leukemia (CLL), we initiated a trial of combined pentostatin (2 mg/m2), cyclophosphamide (600 mg/m2), and rituximab (375 mg/m2) for 65 symptomatic, previously untreated patients. Of 64 evaluable patients, 34 (53%) were high Rai risk, 71% were nonmutated for the immunoglobulin heavy-chain variable region gene, 34% were CD38+, and 34% were ZAP-70+. Thirty patients (52%) had one anomaly detected by fluorescence in situ (FISH) hybridization, and 21 (36%) had complex FISH defects. Thirty-eight patients (58%) had grade 3+ hematologic toxicity but minimal transfusion needs and no major infections. Responses occurred in 58 patients (91%), with 26 (41%) complete responses (CRs), 14 (22%) nodular partial responses (nodular PRs), and 18 (28%) partial responses (PRs). Many patients with a CR also lacked evidence of minimal residual disease by 2-color flow cytometry. Examination of prognostic factors demonstrated poor response in the 3 patients with del(17p). In contrast, we found this regimen was equally effective in young versus older (>70 years) patients and in del(11q22.3) versus other favorable prognostic factors. Thus, this novel regimen of pentostatin, cyclophosphamide, and rituximab for previously untreated patients with CLL demonstrated significant clinical activity despite poor risk-based prognoses, achievement of minimal residual disease in some, and modest toxicity.

Major advances in the management of patients who have hairy cell leukemia have been made following the use of purine nucleoside analogs. Pentostatin and cladribine are equally effective, and have impressive long-term effectiveness. Although the degree of myelosuppression may be less with the use of pentostatin, this may reflect differences in the schedule and dose of drug administration between these agents. The gradual, but relentless, improvement in the peripheral blood counts enables out-patient management with pentostatin in most patients. Cladribine affords the convenience of a single course of administration. A direct comparative study with these two agents is unlikely to yield the optimal management of patients who have minimal residual disease following the administration of either agent is warranted in the context of a clinical trial. Patients do relapse, and the overall survival curves have not reached a plateau, which indicates that cure has not been secured. The satisfaction of having improved the outcome for patients who have this previously untreatable leukemia should not give way to complacency for further improvement in the management of this disease. Future studies should be directed to optimizing the therapy for minimal residual disease as well as clearer definition of supportive care.

(1) Hairy-cell leukaemia is a chronic lymphoid malignancy occurring in adulthood. It is rare and progresses slowly. The median survival time without treatment is about 4 years. The main presenting signs are infections and cytopenias (anaemia, thrombocytopenia, leukopenia). (2) Treatment is usually based on the purine analogues cladribine and pentostatin. About 80% of patients treated with cladribine or pentostatin survive for at least 10 years. (3) The main adverse effect of these treatments is the risk of infection, especially by Pneumocystis and herpes viruses, due to immunosuppression. Secondary cancers are frequent, but it is difficult to tell the extent to which these are caused by the disease or its treatment. (4) Interferon alfa and splenectomy are generally used when purine analogues fail.

BACKGROUND AND OBJECTIVE: Hairy cell leukemia (HCL) is a rare chronic B-cell lymphoproliferative disorder which is treated effectively by interferon-alpha (IFN-alpha), deoxycoformycin (DCF) and 2-clorodeoxyadenosine (2-CdA). As a third of patients treated with DCF do not achieve a complete remission (CR) and many of them tend to relapse, we evaluated the potential role of IFN-alpha, randomly administered after DCF, in increasing the number of patients attaining CR and/or duration of CR.
METHODS: From March 1997 to December 2000, 167 previously untreated HCL patients, from 37 Italian institutions, were enrolled in the study. A total of 138 males and 29 females, with a median age of 55 yr were included in the study. All patients received six courses of DCF 4 mg/m(2) i.v. every other week and then two additional courses once a month. Complete and partial responders were randomly assigned to receive or not receive IFN-alpha at a dose of 3 MU s.c. three times a week for 6 months.
RESULTS: Of the 167 patients enrolled in the study, 145 (86.8%) obtained a CR or a partial remission (PR) and were therefore suitable for randomization. One hundred and thirty-five patients were successively randomized to receive IFN-alpha (63 cases; arm A) or not (72 cases; arm B). Progression of disease was observed in eight (arm A) and 12 (arm B) patients with a median time of 27.8 and 26.9 months, respectively. As far as the improvement in response was concerned, no significant difference in the two subgroups was observed. In fact, five patients in arm A and six patients in arm B showing a good PR at the end of DCF therapy, subsequently attained a late CR.
CONCLUSIONS: From our data there does not appear to be any significant role for IFN-alpha in improving the proportion and the duration of CR in HCL patients previously treated with DCF.

Pentostatin has been shown to be active in a variety of B- and T-cell malignancies. The drug is a tight inhibitor of adenosine deaminase, a key degradative enzyme of purine metabolism present in all human tissues, with the highest levels found in the lymphoid system. Early clinical trials indicated that this agent was highly active in acute lymphoblastic leukemias with high intracellular adenosine deaminase levels. Relatively high doses of the drug were needed, which was associated with severe adverse events. Through the efforts of a few investigators, better tolerated, low-dose regimens have been shown to be extremely active in lymphoproliferative diseases with very low intracellular adenosine deaminase levels such as hairy cell leukemia, B- and T-cell chronic leukemias, T-cell cutaneous lymphomas and low-grade non-Hodgkin lymphomas. Clinical as well as experimental data have indicated that this drug induces lymphocyte-specific cytotoxicity, and myelosuppressive adverse events have been minimal. Although all the purine analogs have shown similar activity, the advantage of pentostatin is the relatively specific cytotoxicity against lymphocytes, which permits treatment even in patients with severe cytopenias. Although no direct comparisons of the purine analogs have been performed, pentostatin may be preferred due to this property.

BACKGROUND: Both pentostatin and cladribine have efficacy in hairy cell leukemia (HCL), but it is not known which agent achieves better results.
METHODS: We reviewed a series of 219 patients with HCL, with median follow-up from diagnosis of 12.5 years (range 1.0 -34.6 yrs), treated with either pentostatin (n = 185) or cladribine (n = 34), to compare these agents and assess the potential for cure.
RESULTS: Overall response to pentostatin was 96% with a complete response (CR) in 81% and a median disease-free survival (DFS) of 15 years. Response to first-line cladribine was 100% with a CR in 82% and DFS of 11+ years. The relapse rates at 5 years and 10 years were 24% and 42%, respectively, with pentostatin, and 33% and 48% with cladribine. Survival at 10 years was respectively 96% and 100%. CR rates decreased with each sequential relapse through 69% to 45% (P < or = 0.001). Patients achieving CR after first-line treatment had a significantly longer DFS (P = 0.00007) than those achieving a partial response; a similar result was seen after second-line therapy (P = 0.00001). DFS also declined with sequential treatment (P = 0.00005).
CONCLUSION: We have shown equivalent efficacies for both agents in the treatment of HCL, with DFS showing no plateau. True cure in HCL remains elusive, but the addition of monoclonal antibodies may be beneficial. Our results suggest that achieving CR should remain the main goal of treatment.

BACKGROUND: Splenic marginal zone lymphoma (SMZL) is an infrequent B-cell neoplasm that pursues an indolent course. Signs and symptoms, mostly related to hypersplenism, are successfully managed by splenectomy. However, the therapy of patients who are not fit for a surgical procedure or who relapse after splenectomy, is still an unsettled issue.
PATIENTS AND METHODS: We report a phase-II study on 16 patients with SMZL, three therapy naïve and 13 pretreated, all showing systemic symptoms or progressive worsening of peripheral cytopenia, who were treated with pentostatin at a dose of 4 mg/m2 every other week for 6-10 wk. In relapsed patients, the median interval between diagnosis and treatment was 26 month (range: 8-49).
RESULTS: Overall, 68% of the patients showed a clinical response. Two out three patients, who received pentostatin as first line therapy, attained a complete response (CR). One CR and seven minor or good haematological responses were recorded in relapsed patients. Treatment toxicity, mostly haematological, proved manageable. With a median follow-up of 35 month the median overall survival (OS) is 40 month and the median progression free survival (PFS) is 18 month.
CONCLUSION: Our data show that pentostatin administered every other week has a good degree of activity in the treatment of SMZL and suggest that this schedule could be considered a possible therapeutic option for patients who are not fit for splenectomy or have relapsed.