Plasma levels of soluble CD8 antigen and interleukin-2 receptor antigen in patients with hairy cell leukemia, relationship with splenectomy and with clinical response to therapy

A soluble form of CD8 antigen (sCD8) has been shown to be released by activated CD8 + lymphocytes. Measurements of sCD8 may serve as an index of suppressor/cytotoxic cell activity. To assess the clinical significance of this observation in response to malignancy, we have investigated the sCD8 concentrations in 38 patients with hairy cell leukemia (HCL) not yet treated with any systemic therapy. The median plasma sCD8 level of the 20 nonsplenectomized patients was 1,025 U/ml and was significantly higher than that in the 18 patients who had previous splenectomy (median = 200 U/ml, p less than 0.0001), or in 14 normal controls (median = 350 U/ml, p less than 0.0001). Compared to controls, splenectomized patients had also significantly lower levels of sCD8 (p less than 0.01). The median concentration of soluble interleukin-2 receptor (sIL2R) in nonsplenectomized patients was 14,500 U/ml and was in the same range as in splenectomized patients (15,000 U/ml). There was no overlap in sIL2-R levels between controls (median = 300 U/ml) and patients. Investigation of serial plasma samples in 7 patients who received deoxycoformycin (DCF) and 11 patients treated with interferon alpha (IFN-alpha) showed a normalization of sCD8 levels and a decrease of sIL2R concentrations in those patients who showed hematological improvement. Normalization of sIL2R was, however, only observed in patients with complete remission. Our observation indicates that splenectomy might cause a reduction of the activation of suppressor/cytotoxic cells in patients with HCL. Treatment with either DCF or IFN-alpha also modulates the sCD8 levels to normal range. Measurements of sCD8 and sIL2-R might give more insight into the pathogenesis of HCL and serve as parameters for monitoring different phases of the disease and response to therapy.

Response to pentostatin in hairy-cell leukemia refractory to interferon-alpha. The European Organization for Research and Treatment of Cancer Leukemia Cooperative Group

Interferon-alpha (IFN-a) or 2'-deoxycoformycin (pentostatin; DCF) have each been shown to be highly active in hairy-cell leukemia (HCL). In this phase II study of the Leukemia Cooperative Group of the European Organization for Research and Treatment of Cancer (EORTC), the efficacy and toxicity of DCF were investigated in patients who were resistant to IFN-a treatment. Resistance was defined as: (1) progressive disease (PD) under IFN-a therapy for more than 2 months; (2) stable disease (SD) after more than 6 months of IFN-a treatment; (3) relapse within 3 months of discontinuing IFN-a; and (4) intolerance to IFN-a because of World Health Organization (WHO) grade 3 or 4 toxicity. DCF was applied at a dosage of 4 mg/m2 weekly x 3, then 4 mg/m2 every other week x 3. Responders were given a maintenance therapy once per month for a maximum of 6 months. At the time of report, 33 patients with resistant disease were evaluable for response and toxicity. Median duration of IFN-a therapy before DCF administration was 14.7 months (range, 1 to 41 months). Complete remissions (CRs) were achieved in 11 patients and partial remissions (PRs) in 15, resulting in a total response rate of 78.8%. Median interval between beginning of DCF therapy to best response was 3.9 months with a range from 2.0 to 7.0 months. Two patients who achieved PR have relapsed 7 and 14 months after cessation of DCF therapy. The median duration of response was over 11.5 months (range, over 3.0 to over 24.0 months). Three patients died within the first 6 weeks of DCF treatment: one of drug-unrelated cardiomyopathy and two of fungal pneumonia. The patients with early death (n = 3) and nonresponsive disease (n = 4) received IFN-a treatment for a longer period (median, 18.0 months) than did the 26 responsive patients (median, 10.0 months). Major side effects included nausea, skin rash, and infections and were otherwise mild. Thus, DCF is highly active in patients with HCL resistant to IFN-a.

Pentostatin in chronic lymphocytic leukemia: a phase II trial of Cancer and Leukemia group B

We conducted a phase II trial of deoxycoformycin (pentostatin [DCF]) in chronic lymphocytic leukemia (CLL). Eligibility criteria included age greater than 18 years, Cancer and Leukemia Group B (CALGB) performance status 0 to 2, lymphocyte count greater than or equal to 15,000 cells/microL, international stage B or C disease (multiple lymph nodes involved and/or hemoglobin [Hgb] less than 11 g and/or platelets less than 100,000/microL) and no more than one prior treatment regimen. DCF dose was 4 mg/m2 intravenously (IV) weekly for 3 weeks and then every 2 weeks. There were 39 eligible patients (35 men and four women; median age, 63 years; median time from diagnosis to study entry, 3 years). Of these 39 patients, 31% were stage B and 33% had no prior treatment. Median laboratory values at entry were Hgb 10.5 g, WBC 96,100/microL, and platelets 93,500/microL. Nodal involvement was present in 90%, splenomegaly in 81%, and hepatomegaly in 47%. Patients received a median of nine DCF injections, with a range of four to 26. Three patients were not evaluable for response. Overall, 3% achieved a complete response (CR), 23% a partial response (PR), 28% showed clinical improvement (CI), and 38% had stable disease (SD). Associated toxicities (grade 2 or worse) observed were infections (52%), worsening of thrombocytopenia (26%) or anemia (33%), nausea and vomiting (31%), rash or pruritus (20%), and stomatitis (8%). We conclude that DCF is an active agent in CLL with acceptable toxicity.

[Adult T-cell leukemia (ATL)]

Adult T-cell leukemia (ATL) was first discovered and reported in Japan, where it has a high incidence in the southwest region. The retrovirus HTLV-I (human T-cell lymphotropic virus type I) is considered to be related to its etiology. In ATL endemic areas, HTLV-I carriers are found at a fairly high percentage even among healthy individuals. ATL shows diverse clinical features. It can be divided into 5 types (acute type, chronic type, smoldering type, crisis type, and lymphoma type). ATL cells originate from the CD4-positive subset of peripheral T cells; they show a characteristic notch in the nucleus and a lobulation tendency. ATL resists chemotherapy, and patients with acute and lymphoma types have quite a poor prognosis. A definite diagnosis of ATL is made by documenting the presence of HTLV-I proviral DNA in the DNA of tumor cells. HTLV-I infection is caused by transmission of live lymphocytes via three routes (from mother to children, from males to females, and by transfusion). Familial occurrence of ATL is frequently seen. HTLV-I infection is also seen in other countries, but its incidence is highest in Japan. It is thus an urgent task for Japanese physicians to eliminate HTLV-I infection.

Pentostatin in hairy cell leukemia: treatment by the special exception mechanism

An analysis of the clinical outcomes in 66 patients with hairy cell leukemia treated with pentostatin under the Special Exception mechanism of the Division of Cancer Treatment, National Cancer Institute, between 1983 and 1987 has revealed a favorable balance of risk and benefit. Hematologic parameters and performance status were improved in most patients treated outside the clinical trials mechanism. The treating physicians considered 37 patients (56%) to be complete responders and 15 patients (23%) to be partial responders. Four patients (6%) died while receiving pentostatin. Life-threatening leukopenia (wbc count, less than 1,000/mm3) was reported in 24% of patients, and severe or life-threatening infection occurred in 11%. The experience gained with these patients supplements the information presently being collected from the controlled clinical trials and supports the development of a group C treatment protocol.

Hairy cell leukemia. A therapeutical update

This is a review of current treatment for hairy cell leukemia (HCL). Data for this analysis were obtained from the Italian HCL Registry, as well as from other published series. We have given space to the impact of interferon and pentostatin on the management of this disease. Other issues are also discussed, such as the relevance of achieving a complete remission with respect to overall and relapse-free survival. We include a final section on recommendations which may prove useful in designing an appropriate therapeutic strategy.

Deoxycoformycin antagonizes ischemia-induced neuronal degeneration

Deoxycoformycin, a potent and specific adenosine deaminase antagonist, reduced ischemic hippocampal damage and the associated hypermotility in Mongolian gerbils. Cerebral ischemia was induced by a bilateral 5 min occlusion of the carotid arteries. Deoxycoformycin (500 micrograms/kg IP), administered 15 min prior to ischemia, prevented the increase in locomotor activity normally observed with this model and significantly reduced the ischemia-induced damage to CA1 hippocampal neurons. The results suggest that deoxycoformycin may be useful in the prevention of brain damage due to cerebral ischemia.

Pentostatin in the treatment of advanced hairy cell leukemia

2'-Deoxycoformycin (pentostatin [dCF]), a potent inhibitor of adenosine deaminase (ADA), was administered in a biweekly low-dose (2 to 4 mg/m2) intravenous (IV) schedule to patients with advanced hairy cell leukemia. Twenty-three patients were treated, including 12 patients previously treated by splenectomy and five patients treated with interferon. Twenty-one of 23 patients had objective responses, including 20 who achieved a complete remission (CR). Responses occurred rapidly, with an average time to CR of 5.4 months. Treatment was not continued once CR was achieved, and 15 of 20 patients remain in remission with an average duration of 12.6 months. CRs were achieved in both patients previously treated with interferon (three of five) and patients with marked splenomegaly (three of three). Relapses, when seen, have occurred in the bone marrow alone and the one patient who required retreatment was reinduced into CR. Toxicity has been mild and reversible, with nausea and vomiting, conjunctivitis, and skin rash as the main complications of treatment. dCF is the most effective single agent in the treatment of hairy cell leukemia, inducing a high percentage of CRs in all subgroups. Two multiinstitutional trials are now underway to compare its effectiveness v alpha interferon.

Peripheral blood and bone marrow changes following 2'-deoxycoformycin therapy in hairy cell leukemia. Results of 200 weeks' follow-up

Peripheral blood (PB) and bone marrow (BM) changes during 200 weeks' follow-up of 15 patients with hairy cell leukemia (HCL) undergoing low-dose 2'-deoxycoformycin (dCF) therapy are reported. Thirteen patients rapidly achieved complete remissions (CR) (median, 16 weeks). Previous splenectomy (two patients), or chemotherapy (two patients) had no effect on dCF response. Twelve patients have remained in CR. Patients with marked BM infiltration (hairy cell index [HCI] greater than 0.5; n = 5) had more pronounced pancytopenia and showed a slower hematologic recovery than those with a lesser degrees of infiltration. Additionally, patients with cytologic type II HCL (n = 5) had more pronounced pancytopenia with a greater tumor load in the BM, and exhibited slower hematologic recovery than those with type I (n = 5) HCL. There was a gradual decline in BM cellularity from 65% to 25% during year 1, a level which remained stable thereafter. Reticulin in the BM regressed in all nine patients in whom it was increased before dCF therapy. The authors have not seen any dysplastic changes in the hematopoietic cells during the period of follow-up.

Pentostatin (2'deoxycoformycin) for the treatment of lymphoid neoplasms

Knowledge of the vital role of adenosine deaminase in lymphatic tissues has led to the development of enzyme inhibitors for treatment of lymphoid neoplasms. Deoxycoformycin is a potent ADA inhibitor and has been shown to be active in acute lymphoblastic leukemia at high doses but associated with unpredictable toxicity. In indolent lymphocytic leukemia or lymphoma with low ADA concentrations, this drug is effective at low doses with mild toxicity. The on-going EORTC trial shows that pentostatin is highly effective in hairy cell leukemia and can achieve durable complete remissions even if interferon alpha has failed. It will probably play an important role in the treatment of prolymphocytic leukemia, T- and B-cell chronic lymphocytic leukemia and Sézary syndrome.

Deoxycoformycin-induced immunosuppression in patients with hairy cell leukemia

Immune function in patients with hairy cell leukemia (HCL) was examined serially during treatment with alternating monthly cycles of recombinant interferon alpha-2a and 2'-deoxycoformycin (dCF). At presentation, most patients had normal numbers of T lymphocytes and their cells had normal proliferative responses to mitogens [phytohemagglutinin (PHA) and concanavalin A (Con A)] and alloantigens. Patients had severe monocytopenia, decreased delayed-type hypersensitivity (DTH) reactions, and decreased peripheral blood natural killer (NK) activity. Treatment caused a profound decrease in all lymphocyte subpopulations. T cells were more affected than B cells or NK cells. Numbers of CD4+ and CD8+ lymphocytes decreased to levels less than 200 cells/microliters in all patients during treatment. This decrease in T cell number was associated with a marked decrease in proliferative responsiveness to PHA, Con A, and alloantigens. These abnormalities persisted throughout the 14 months of treatment and have continued for up to 6 months beyond discontinuation of treatment. NK cell activity increased during treatment, but cycled depending on the phase of treatment; highest activities were observed after interferon (IFN)-alpha and lower levels of activity were observed after dCF. DTH responses generally did not improve during therapy. Levels of IgM, IgG, IgA, and IgD did not change during treatment, but IgE levels rose in most patients. All immunosuppressive effects were attributable to dCF since patients receiving IFN-alpha 2a alone did not exhibit these same immunosuppressive effects, and patients receiving dCF alone after IFN failure exhibited similar abnormalities. Despite this severe immunosuppression from dCF, life-threatening opportunistic infections have not been observed in our patient population. Six patients developed localized Herpes zoster infection among 21 patients who had received dCF. Pending the results of long-term follow-up, we recommend that dCF be reserved for patients who have failed splenectomy and IFN therapy.

Immunohistological assessment of bone marrow biopsies from patients with hairy cell leukemia: changes following treatment with alpha-2-interferon and deoxycoformycin

Forty-six bone marrow biopsies from twelve hairy cell leukemia (HCL) patients, treated with either interferon(IFN)-alpha-2 (n = 8) or 2'deoxycoformycin(DCF) (n = 4), were examined using cryostat sections and an immunoperoxidase technique. Using this sensitive method we were able to demonstrate residual hairy cell (HC) infiltration in five cases, in which evaluation with conventional staining techniques on plastic embedded biopsies revealed complete remission. The amount of HCs in these five samples ranged from 1 to 7% (mean: 3%) of bone marrow cells. Consecutive biopsies in individual HCL patients revealed no changes of the immunological phenotype (CD19, CD22, CD25, CD10, CD11c, FMC7, HLA-DR, surface immunoglobulins) during IFN and DCF treatment. Within the infiltrated bone marrow a considerable number of "reactive" T lymphocytes was identified with prevalence of the T-helper (CD4+) subtype in untreated cases, whereas T-suppressor/cytotoxic (CD8+) cells were within the normal range. IFN treatment resulted in a reduction of CD4+ T lymphocytes (p less than 0.02). Minor alterations of CD8+ T lymphocytes and NK cells (HNK-1 + lymphoid cells) were found in bone marrow during IFN treatment. In DCF-treated patients bone marrow T lymphocytes were markedly reduced below the values of normal bone marrow. This DCF-induced T-cell depression might be related to the clinical observation of persistent cellular immune dysfunctions in HCL patients despite a DCF-induced remission.

[Therapeutic aspects of hairy cell leukemia]

This work considers the new advances in hairy cell leukemia therapy. During the last decades the only useful treatments were splenectomy, or, in case of failure or relapse, various chemotherapeutic approaches. Sometimes leukapheresis, radiotherapy, androgens, allogenic bone marrow transplantation, corticosteroids and lithium salts were used with few good results. Interferon and 2-deoxicoformycin recently introduced for the treatment of HCL have determined a dramatic change in the outlook of this disease, producing a high percentage of complete and partial remission.

Clinical response to deoxycoformycin in chronic lymphoid neoplasms and biochemical changes in circulating malignant cells in vivo

Deoxycoformycin (DCF), an adenosine deaminase (ADA) inhibitor, has been shown to be active in lymphoid neoplasms. The mechanism of cytotoxicity might involve accumulation of deoxyadenosine triphosphate (dATP), depletion of the nicotinamide adenine dinucleotide (NAD) and ATP pool, induction of double-stranded DNA strand breaks, or inhibition of S-adenosyl homocysteine hydrolase (SAH-hydrolase). We have investigated the biochemical changes in the circulating malignant cells of patients with chronic leukemia/lymphoma who were treated with DCF (4 mg/m2 weekly). Blood samples were taken from 17 patients with 60% or more circulating leukemic cells before, 4, 24, and 48 hours and five days after the first administration of DCF. Leukemic cells were separated and studied for changes in ADA, dATP, ATP, NAD, and SAH-hydrolase levels and DNA strand breaks and the data analyzed according to clinical response. Inhibition of ADA activity was found in all except one patient at 4 to 24 hours after the first administration of DCF. dATP started to accumulate at four hours, reached a maximum level between 24 and 48 hours, and returned to base values on the fifth day. Intracellular ATP and NAD levels were transiently reduced in some of the patients. However, no correlation between these changes and a clinical response could be found. DNA strand breaks could be studied in 13 patients. A significant increase in DNA breaks at 24 to 48 hours was found in six of the seven responders but only in one of the six nonresponders. At 24 hours, SAH-hydrolase levels were reduced in all seven responders studied, but only in two of the seven nonresponders. The difference in inhibition of SAH-hydrolase was statistically significant (P = .0023). These results suggest that DNA strand breaks and inhibition of SAH-hydrolase correlate with clinical response.

Clinical, pharmacologic, and immunologic effects of 2'-deoxycoformycin

Clinical, pharmacologic, and immunologic effects of 2'-deoxycoformycin (dCF) were evaluated in 15 patients with advanced malignancies. Toxicity was less severe with a low dose (4 mg/m2) of dCF, but this dose still resulted in suppression of cellular adenosine deaminase activity, skin test reactivity, and lymphocyte responses to mitogens. Improvement in cutaneous T cell lymphoma plaques was seen after dCF. Further investigations of antitumor efficacy with the use of this low dosage schedule should continue in patients with hematologic neoplasms, and additional preliminary studies of the combination of an adenosine deaminase inhibitor with an adenosine analog should also be considered.

Treatment of cutaneous T cell lymphoma with 2'-deoxycoformycin (pentostatin)

2'-Deoxycoformycin, a potent inhibitor of adenosine deaminase, was administered to three patients with cutaneous T cell lymphoma refractory to multiple treatment modalities. Patient 1, who received 5 mg/m2/day for 3 days at 35- to 71-day intervals, has achieved a complete remission greater than 16 months in duration. Patient 2 had progressive disease despite two courses of 2'-deoxycoformycin at a dose of 5 mg/m2/day for 3 days at 28-day intervals. The third patient, who was treated with 4 mg/m2 2'-deoxycoformycin weekly to biweekly, had an initial response, but the disease progressed after eight treatments. Only one patient had any side effects: Patient 1 developed reversible episcleritis, mild elevation of liver enzymes, and persistent nausea and vomiting. In red blood cells of all patients, there was near complete inhibition of adenosine deaminase (91% to 96%) and S-adenosylhomocysteine hydrolase (89% to 95%) activities with treatment. In peripheral blood lymphocytes, adenosine deaminase was inhibited by 85% to 98% and S-adenosylhomocysteine hydrolase by 51% to 88%. The deoxyadenosine triphosphate level, reflected by the total cellular adenine deoxyribonucleotide measurement in erythrocytes, was noted to be modestly elevated during treatment, with the highest level in the patient who demonstrated the only complete response and the only toxic effects. Low-dose 2'-deoxycoformycin appears to be safe but may be an insufficiently intensive regimen to treat refractory cutaneous T cell lymphoma. With proper biochemical monitoring, higher doses may be both safe and more effective.

Efficacy of 2'-deoxycoformycin in hairy-cell leukemia: a study of the National Cancer Institute of Canada Clinical Trials Group

Thirty-one patients with hairy-cell leukemia were treated with 2'-deoxycoformycin (DCF) in a National Cancer Institute of Canada multicenter trial. The DCF was administered in a cycle (4 mg/m2 iv weekly X 3), which was repeated every 8 weeks. Following a complete remission, consolidation was done with two further cycles of DCF. Of 28 patients evaluable for response, 25 obtained a complete remission; 3 had a partial response. To date there has been only one relapse; the median time with no therapy was 429.5 days (range 99-743 days). Toxicity was moderate and included nausea and vomiting, lethargy, and skin rash; with the first cycle of treatment, neutropenia and an increased incidence of fever or infection were also observed. We conclude that low-dose DCF is highly effective in treating hairy-cell leukemia.

Enzymes of purine metabolism in lymphoid neoplasms, clinical relevance for treatment with enzyme inhibitors

A few enzymes of the purine degradative pathway have proved valuable in diagnosis and treatment of lymphomas and lymphocytic leukemia. Of particular interest are the enzymes adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and ecto-5'-nucleotidase (5NT). Intact activities of ADA and PNP have been shown to be vital for lymphoid cells. During development, lymphoid precursors go through remarkable changes in the concentrations of these enzymes and the neoplasms derived from them show a "frozen" biochemical profile similar to the corresponding normal cell of origin. Knowledge of the role of these enzymes has led to the pharmacological use of enzyme inhibitors for the specific treatment of lymphoid neoplasms. This review concerns the enzymatic make-up of normal and neoplastic lymphocytes and exploitation of this knowledge for the treatment of lymphomas. Special emphasis will be put on the clinical use of an ADA-inhibitor, deoxycoformycin.

2'-Deoxycoformycin (pentostatin) for lymphoid malignancies. Rational development of an active new drug

A new antimetabolite, 2'-deoxycoformycin (pentostatin), has striking antitumor activity in several lymphoid neoplasms. Isolated from cultured soil organisms, this purine analogue is a potent inhibitor of adenosine deaminase (ADA), and is thus selectively toxic to lymphocytes. Early clinical trials showed that high doses of pentostatin caused severe and unpredictable toxicity, but responses in refractory lymphoid malignancies were encouraging. Careful pharmacologic studies led to the definition of a safe and effective low weekly dose, at which protracted ADA inhibition occurs in neoplastic cells. The most sensitive tumor identified is hairy cell leukemia, in which durable remissions are achieved in more than 90% of patients with a relatively brief course of treatment. Other responsive diseases include chronic lymphocytic leukemia, prolymphocytic leukemia, mycosis fungoides, and acute T-cell lymphoma or leukemia. Response has been seen in acute lymphocytic leukemia, but the higher doses required are substantially more toxic. Pentostatin is valuable for treatment of indolent lymphoid malignancies and may be useful in non-cancer-related lymphocyte research.

Serum soluble IL-2 receptor as a tumor marker in patients with hairy cell leukemia

Activated T cells synthesize and express a cell membrane-bound receptor for interleukin-2 (IL-2) and have recently been shown to secrete a soluble form of the same receptor. Hairy cell leukemia is a chronic disorder caused by expansion of a clonal population of an unusual mononuclear cell of B cell origin. These cells have previously been shown to express an IL-2 receptor on the cell membrane. The sera of 26 patients with hairy cell leukemia were examined for the presence of a soluble IL-2 receptor before and during therapy with either recombinant interferon alpha-2a or 2'-deoxycoformycin. Before therapy, all patients had markedly elevated levels of this soluble IL-2 receptor ranging from five to 60 times the highest level observed in normal control sera. In individual patients changes in the level during therapy correlated well with clinical assessments of tumor response; levels fell to near the normal range in patients responding to therapy. Patients not responding to interferon alpha had no significant change in the soluble IL-2 receptor level. These results suggest that hairy cells secrete a soluble IL-2 receptor and that serial measurements of the level of this receptor in the serum can be used as a noninvasive means to assess disease response to therapy.

Cutaneous presentation of prolymphocytic leukaemia

We report a case of prolymphocytic leukaemia which presented with annular, purpuric, erythematous plaques in the skin. Histology of the lesions showed cutaneous invasion with leukaemic cells. The lesions cleared with chlorambucil and prednisolone, and the leukaemic state responded to deoxycoformycin, an experimental anti T cell agent.

Regression of intracerebral lesions in T prolymphocytic leukaemia treated with intravenous deoxycoformycin

A case of T-prolymphocytic leukaemia (T-PLL) presenting with deafness and confusion is reported. Computerised tomography (CT) of the head showed several well-defined, rounded, high attenuation areas in the temporal, parietal and occipital regions of the brain substance that were suggestive of metastases. Treatment with weekly intravenous deoxycoformycin produced complete resolution of the CT abnormalities together with haematological evidence of disease regression 6 weeks after treatment was started.

Deoxycoformycin in therapy of refractory lymphoid neoplasms

Knowledge of the vital role of the purine degradative enzyme adenosine deaminase (ADA) in the differentiation of T and B lymphocytes has stimulated interest in the pharmacologic inhibition of ADA as specific cytotoxic therapy for lymphoproliferative diseases. 2'-Deoxycoformycin (DCF) is a tight-binding ADA-inhibitor and has shown activity in T and B cell neoplasms. In this phase-II study, the efficacy and toxicity of DCF in chronic T and B cell neoplasms is investigated. We report the preliminary results of treatment in 27 patients (8 with Sézary syndrome, 11 with B-chronic lymphocytic leukemia (CLL), and 8 with hairy cell leukemia (HCL)), who were refractory to conventional therapy. DCF was applied at a dosage of 4 mg/m2 weekly x 3, then 4 mg/m2 every other week x 3. Three of the 8 patients with Sézary syndrome and 3 of the 11 patients with B-CLL attained a partial remission. One complete and 7 partial remissions have been achieved thus far in the 8 patients with HCL refractory to interferon alpha treatment. Other than nausea in 10 patients (mainly grade 1 and 2), transient skin rash in 4 patients and Herpes infections in 4 patients (mainly grade 2), no other major toxicities were observed. Thus DCF is highly active in hairy cell leukemia that did not respond to interferon alpha, and shows moderate activity in refractory Sézary syndrome and B-CLL.

Rapid response to 2'-deoxycoformycin in advanced hairy cell leukemia after failure of interferons alpha and gamma

A patient with advanced hairy cell leukemia initially had a short-lived minor response to interferon alpha therapy and failed to respond to interferon gamma. Subsequent treatment with 2'-deoxycoformycin (dCF) administered biweekly for 12 wk resulted in a complete hematological remission which has continued for 16 months without additional therapy.

Deoxycoformycin treatment for childhood T-cell acute lymphoblastic leukemia early in second remission: a Pediatric Oncology Group Study

2-Deoxycoformycin (DCF) was added to an intensive Pediatric Oncology Group protocol (#8303) for children with T-cell acute lymphoblastic leukemia or T-cell lymphoblastic lymphoma in first relapse. Twenty-seven patients received one or more courses of DCF at 15 mg/m2/day as a 3-day continuous infusion immediately after achieving a second remission with a four-drug reinduction regimen. Renal and neuromuscular toxicities were frequent and occasionally severe despite the provision of a source of adenosine deaminase by means of a packed red cell transfusion 1 day following the infusion of DCF. Hepatic toxicity, manifested by transaminase elevations, accompanied 62% of the courses. The median duration of the second complete remission was 4 months (range 2-16+ months), with only two of the 27 patients still in remission at 13+ and 16+ months. Plasma concentrations of deoxyadenosine (dAdo) and the ratio of red cell deoxyadenosine triphosphate to adenosine triphosphate (dATP:ATP) were measured prior to the DCF infusion and on day 4. A dATP:ATP ratio of 1.0 or greater was seen in two patients with acute renal failure. There was no apparent correlation between toxicity or response and the plasma dAdo concentrations. DCF administered according to this dose and schedule was excessively toxic and did not appreciably prolong the duration of the second complete remission in children with T-cell lymphoblastic malignancies.

2'-Deoxycoformycin therapy in adult T-cell leukemia/lymphoma

Six Caribbean patients with histologically and immunologically characterized adult T-cell leukemia/lymphoma (ATL) were treated intravenously (IV) with 2'-deoxycoformycin (DCF) at a dose of 5 mg/m2 on days 1, 2, 8, 15, and 22 with four additional weekly doses to convert any partial responses (PR) to complete responses (CR). Patients were considered eligible for this study if refractory to or relapsed from combination chemotherapy, had a life expectancy of 4 weeks or more, a performance status greater than or equal to 50%, normal renal and hepatic function, and no chemotherapy within 4 weeks. Clinical characteristics of the patients in this study included lymphadenopathy in five patients, skin involvement in four patients, bone marrow infiltration in five patients, and central nervous system involvement in two patients. Circulating ATL cells were present in four patients, and three were hypercalcemic. Of five patients evaluable for response, there was one PR of 1 month, and two minor responses lasting 2 and 3 weeks. The median duration of survival for all treated patients was 3 weeks or more. The DCF was associated with moderate side effects, including conjunctivitis in three patients, nausea and vomiting in two patients, progressive hepatic insufficiency in one patient, and moderate myelotoxicity in three patients. Infections occurred in four patients, including two cases of oral candidiasis and two cases of fatal neutropenic sepsis in patients receiving concurrent intrathecal methotrexate. As a single agent, DCF appears to have limited activity in advanced refractory/relapsed ATL. Studies in the future should explore DCF in combination with other cytotoxic agents as initial therapy in better-risk patients.

Hairy cell leukemia: clinical features and therapeutic advances

Hairy cell leukemia (HCL) is a rare chronic lymphoproliferative disorder which has been extensively studied over the past decade. Much has been learned regarding the diagnosis, natural history, biology, and treatment of this unique neoplasm. The disease most commonly affects middle aged men and characteristic clinical features include splenomegaly, cytopenias, and usually the presence in the peripheral blood of distinctive 'hairy cells' with irregular cytoplasmic projections. Diagnosis can usually be confirmed by bone marrow biopsy. Although the natural history can be extremely variable among patients, complications are usually referable to the cytopenias, with anemia and infection being most frequent. In addition to pyogenic infections, patients are susceptible to unusual organisms including atypical mycobacterium, legionella, and fungi. The requirement of red blood cell transfusion, severe granulocytopenia or thrombocytopenia, frequent infections, or painful splenomegaly are all indications for treatment. Splenectomy is the standard initial treatment of choice. However, in the past few years there have been exciting major advances in the therapeutic modalities for HCL. Recombinant alpha-interferon is highly effective, with beneficial responses occurring in close to 90% of patients. The Food and Drug Administration has recently approved the use of interferon for HCL. This represents the first time a biological response modifier has been approved for the treatment of human disease. In addition, preliminary results with the adenosine deaminase inhibitor, 2'deoxycoformycin (dcf), have been encouraging. Further clinical trials are required in order to determine the optimal sequential treatment strategy for HCL. The exact mechanisms of action of both interferon and dcf in HCL remain to be elucidated. A better understanding of the unusual features of the hairy cell and the underlying biological effect of these two agents in HCL may have important applications in other hematologic and non-hematologic malignancies.

2'-Deoxycoformycin (Pentostatin) in hairy cell leukemia: response in patients refractory to interferon alpha

Three patients with advanced hairy cell leukemia received low-dose deoxycoformycin treatment after failure to respond to therapy with interferon alpha. Patients 1 and 2 had progressive disease after splenectomy and subsequent treatment with recombinant interferon alpha (for 7 and 3 months, respectively). DCF was administered at 4 mg/m2 weekly for 3 weeks, and then once every week for 6 weeks. Patient 1 was in complete remission after 9 weeks of treatment and patient 2 in partial remission with normalization of peripheral blood counts. The third patient, also splenectomized, developed hepatotoxicity after therapy trial with interferon for 24 days and no objective improvement was observed at this stage. She subsequently responded to DCF treatment with improvements in blood counts and bone marrow. This report demonstrates that DCF is highly effective in hairy cell leukemia and non-cross-resistant with interferon alpha.

Membrane phenotype and response to deoxycoformycin in mature T cell malignancies

The adenosine deaminase inhibitor deoxycoformycin was used in low doses to treat 19 patients with clinically aggressive T cell malignancy with a mature membrane phenotype. The patients comprised eight with prolymphocytic leukaemia, two with chronic lymphocytic leukaemia, four with adult T cell leukaemia-lymphoma, three with Sézary syndrome, and two with T cell lymphoma. Two thirds of the patients had been resistant or minimally responsive to combination chemotherapy. Complete remission was obtained in five patients (two with prolymphocytic leukaemia and one each with chronic lymphocytic leukaemia, adult T cell leukaemia-lymphoma, and Sézary syndrome) and partial remission in two others. Unmaintained complete remission lasting more than one year was seen in three patients. Responses were obtained only in patients with CD4+,CD8-membrane markers (seven out of 10), and no responses were recorded in any of the nine patients with a different phenotype. In this series remission appeared to correlate with the membrane phenotype of the neoplastic cell and not with the cytopathological diagnosis. Future studies should establish the biochemical basis for the greater sensitivity of CD4+ lymphoid cells to deoxycoformycin.

Biochemical consequences of 2'-deoxycoformycin treatment in a patient with T-cell lymphoma. Some unusual findings

The nucleotide content of the various blood cells and the urinary excretion of purine and pyrimidine metabolites were studied in a patient with a T-cell lymphoma (early T-cell phenotype) before and during treatment with deoxycoformycin (dCF; given intravenously [iv] during 3 days, biweekly). During and after the administration of dCF, high amounts of dATP were found in the lymphoid cells and the erythrocytes (maximally, 480 pmol/10(6) lymphocytes and 5.5 nmol/10(6) erythrocytes), but not in the polymorphonuclear leukocytes. The amount of dATP in the erythrocytes, however, was significantly lower than described in the literature. During each administration of dCF, the number of blast cells in the peripheral blood rose initially, followed by a rapid decrease. After three courses, a hematologic remission was achieved and maintained for 6 weeks; then an autologous bone-marrow transplantation was performed. During the first dCF course a large amount of deoxyadenosine was found in the urine. During the second course, this excretion was much lower, but still higher than in healthy individuals. In the patient described, dCF showed a highly specific toxicity for the immature T-lymphoblast; hardly any changes were seen in the numbers of the other hematopoietic cells, both in the blood and in the bone marrow.

The role of pentostatin (2'-deoxycoformycin, dCF) in the management of lymphoproliferative malignancies

Laboratory and clinical data relating to the use of 2'-deoxycoformycin in human disease are reviewed. Pentostatin is an inhibitor of adenosine deaminase, an enzyme that is important for purine metabolism, but more than one mechanism may be involved in its cytotoxic action. Early studies with dCF employed large doses and for the most part were conducted in patients with acute lymphocytic leukaemia: responses were brief and relatively few, and severe renal, hepatic, and central nervous system toxicity were encountered, leading to temporary abandonment of clinical trials. More recently, it has been shown that dCF is effective in much smaller doses, with considerably less toxicity. It has proved to be more effective in low-grade lymphoid malignancies (chronic leukaemias, indolent lymphomas) than in more undifferentiated neoplasms (acute leukaemias, lymphoblastic and immunoblastic lymphomas), and is outstandingly effective in hairy cell leukaemia, both as initial therapy and after failure of splenectomy and interferon. Pentostatin is profoundly immunosuppressive: generally this is considered a disadvantage but its potential therapeutic exploitation merits investigation. Despite extensive knowledge of its biochemical effects, the optimal dose regimen of dCF and the value of combining it with purine antagonists remain to be defined.

Clinical trials in hairy cell leukemia. Current status and future directions

During the past 5 years, clinical trials in hairy cell leukemia have shown dramatic activity for alpha-interferon and 2'-deoxycoformycin (pentostatin). Responses can be induced in more than 80% of patients using either agent, although a greater number of complete pathologic remissions may be achieved with deoxycoformycin. Despite interesting preliminary data, the optimal dose, schedule, treatment duration, and impact of therapy on survival are unknown. Clinical trials comparing efficacy and toxicity of alpha-interferon and deoxycoformycin, the extent of cross-resistance, and relationship of activity to previous splenectomy are in progress. Additional studies are testing combinations of these agents. Although interferon is commercially available for treating hairy cell leukemia, considering such therapy routine is counterproductive. Long-term clinical trials of interferon and deoxycoformycin are essential to advance our biologic knowledge of this rare disease, and to ensure optimal therapy for a potentially curable malignancy.

Remissions in hairy-cell leukemia with pentostatin (2'-deoxycoformycin)

The Eastern Cooperative Oncology Group conducted a study of pentostatin (2'-deoxycoformycin) in 37 patients with hairy-cell leukemia. Among the 27 patients who met all the study's entry criteria, the response rate was 96 percent, with 16 patients (59 percent) entering complete remission and 10 patients (37 percent) partial remission. In one patient no response was observed. These results were not significantly changed by the inclusion of nine additional patients who were found retrospectively not to have fulfilled the entry criteria. When complete remission was attained, maintenance therapy was not given. Despite this, no patient has had a relapse, and the duration of complete remission ranges from 1 to 375 days. Pentostatin appears to be equally effective in untreated patients and in those who have progressive disease after splenectomy or after both splenectomy and treatment with interferon. Whether pentostatin is superior to splenectomy or interferon as therapy for hairy-cell leukemia will have to be assessed by direct comparison in randomized studies. Lengthy follow-up will be required to determine a median duration for the responses of hairy-cell leukemia to pentostatin.

The treatment of hairy cell leukemia with 2'-deoxycoformycin: results in India and in the United States

We treated 11 patients (nine men and two women) with hairy cell leukemia with low doses of pentostatin (2'-deoxycoformycin). As of January 1987, 10 patients (91%) were in complete remission (CR) and one (9%) was in partial remission. Thus, the overall response rate was 100%. Maintenance therapy was not given once CR was attained, but no patient in CR relapsed: remission durations were from 40+ to 9+ months. For hairy cell leukemia, pentostatin is a better treatment than splenectomy and probably is superior to interferon, but further studies are needed to better define its role in this disease.

Treatment of hairy cell leukemia: the Ohio State University experience with deoxycoformycin

Twelve evaluable patients with progressive hairy cell leukemia were treated with deoxycoformycin at a dose of 4 mg/m2 every 2 weeks. Five patients had not been splenectomized, and one had failed to respond to interferon-alpha. Complete remission, as defined by absence of hairy cells in the bone marrow and normalization of the peripheral blood and regression of splenomegaly, was obtained in 11 of 12 patients (92%). These patients have remained in unmaintained remission for 1+ to 13 months with an average of 7.5 months. Two of these patients had a bone marrow relapse at 8 and 12 months, respectively. During treatment the monocytopenia corrected, and, after complete remission was obtained, marrow was aspirable. Toxicity was mild and reversible. There were no significant infections associated with this treatment. It was of interest that we could treat two patients with creatinine clearance of 50 and 60 ml/min using lower doses (and 2-3 mg/m2) than our conventional therapy of 4 mg/m2 every 2 weeks. They obtained a complete remission after 6 and 10 treatments, respectively. Low-dose deoxycoformycin has proven to be an excellent treatment for hairy cell leukemia.

Therapeutic approaches to the treatment of hairy cell leukemia

Although a rare disease, hairy cell leukemia has great biologic and clinical significance. New therapeutic options of alpha-interferon and pentostatin have challenged the role of splenectomy in the overall management of the disease. alpha-Interferon can now be considered the treatment of choice for patients who progress after splenectomy, and it may also be considered as initial treatment in selected patients. Future clinical trials will focus on the relative efficacies of alpha-interferon and pentostatin, their potential for sequential or combined use, and the role of splenectomy.

Prevention of graft-versus-host disease in allogeneic bone marrow transplantation by pretreatment with 2'-deoxycoformycin

Germ-free mice were used as a model for acute graft-versus-host disease (GVHD) in allogeneic bone marrow transplantation (BMT). C3H/He recipients of DBA/2 cells showed typical symptoms of acute GVHD and died within 8 days. Incubation of the cells with 10 microM 2'-deoxycoformycin (2dCF) + 100 microM deoxyadenosine (dAdo) for 1 h inhibited all T-cell functions as well as T-cell-dependent B-cell functions, but had no effect on B-cell functions that are T-cell independent, nor on the hemopoietic stem cells (CFU-S). Recipients of allogeneic cells that had been incubated with 2dCF + dAdo for 1 h prior to inoculation showed no signs, gross or histological, of acute or chronic GVHD up to 15 months after transplantation. The recovery patterns of the blood and bone marrow were not affected by the treatment, and were similar to those of recipients of treated and untreated syngeneic cells.