Lawrence D. Piro

Lasting remissions in hairy-cell leukemia induced by a single infusion of 2-chlorodeoxyadenosine.

2-Chlorodeoxyadenosine is a simple purine nucleoside that has previously been shown to be effective in the treatment of low-grade malignant disorders of lymphoid tissue, including chronic lymphocytic leukemia and non-Hodgkins lymphoma. Because of these encouraging results, we treated 12 patients with another low-grade B-cell neoplasm, hairy-cell leukemia. The patients received 2-chlorodeoxyadenosine (0.1 mg per kilogram of body weight per day) by continuous infusion for seven days. All the patients responded to treatment. Eleven had complete remissions characterized by the normalization of peripheral blood and bone marrow and disappearance of tumor masses. The longest remission has been 3.8 years. None of the patients have relapsed, and the median duration of remission has been 15.5 months. No serious toxic reactions occurred as a result of 2-chlorodeoxyadenosine therapy. These results suggest that 2-chlorodeoxyadenosine may be the most effective therapy available for hairy-cell leukemia. The administration of 2-chlorodeoxyadenosine resulted in a higher rate of complete remission than is observed with interferon alfa, and it required no maintenance therapy. Its toxicity may be lower than that of deoxycoformycin, and the responses were achieved with single courses of treatment.

2-Chlorodeoxyadenosine treatment of low-grade lymphomas.

PURPOSE Because of the need to identify effective new agents in the treatment of non-Hodgkins lymphoma and because of the high activity of the purine analog 2-chlorodeoxyadenosine (2-CdA) against chronic lymphocytic leukemia and hairy cell leukemia, a phase II trial of 2-CdA was initiated in patients with low-grade lymphocytic lymphomas. PATIENTS AND METHODS Forty patients with low-grade lymphocytic lymphomas including diffuse small lymphocytic, follicular small-cleaved, and follicular mixed histologies were enrolled onto the study. Conventional therapies had failed in all patients, and six patients had lymph node biopsies showing evidence of histologic evolution to a higher-grade lymphoma. A total of 107 courses of 2-CdA were administered. There were 27 males and 13 females. The median age was 59 years (range, 37 to 80 years). Patients had received a median of three prior therapies (range, one to six therapies). RESULTS An overall response rate of 43% was achieved, with eight patients experiencing complete responses (CRs) and nine patients experiencing partial responses (PRs). The duration of responses ranged from 1 to greater than 33 months without maintenance therapy (median duration of response, 5 months). Histology and prior therapy history did not seem to correlate with responses. Significant toxicity was limited to bone marrow suppression; 18% of patients developed neutropenia, and 30% developed thrombocytopenia. CONCLUSIONS This phase II trial demonstrates that 2-CdA is an effective antilymphocyte, antineoplastic agent with significant activity as a single agent in patients with recurrent or refractory low-grade lymphocytic lymphoma. Responses were achieved with an acceptable toxicity profile. Further trials of this agent in previously untreated patients and in combination regimens are indicated and will be developed.

Combination Chemotherapy in Refractory Immune Thrombocytopenic Purpura

BACKGROUND Chronic idiopathic thrombocytopenic purpura is a destructive thrombocytopenia caused by an autoantibody. About 80 percent of patients with chronic idiopathic thrombocytopenic purpura have remissions after either corticosteroid therapy or splenectomy. Some patients with resistant disease respond to other agents, but a substantial group are refractory to therapy. METHODS We used combination chemotherapy to treat 10 patients with refractory immune thrombocytopenia. An average of 6.8 (range, 3 to 10) previous therapies, including corticosteroids and splenectomy, had been unsuccessful in these patients. The patients received from three to eight cycles of therapy consisting of cyclophosphamide and prednisone combined with either vincristine (one patient), vincristine and procarbazine (four patients), or etoposide (six patients, including one patient who received four cycles each containing procarbazine and etoposide). RESULTS Among the 10 patients, 6 had complete responses (platelet count, > 180,000 per cubic millimeter); of these, 4 patients had responses that persisted for more than 11, 30, 54, or 126 months, 1 had a relapse 9 months after therapy but had a remission with further therapy and remained in remission for 48 months before dying of an unrelated illness, and another relapsed just before her fifth course of therapy. Two patients had partial responses (platelet count, > 50,000 per cubic millimeter); the platelet counts in one remained stable for more than nine months after the end of therapy, and the other patient relapsed. The remaining two patients had no response. Complete responses were associated with a disappearance or marked decrease in the level of platelet-associated autoantibody. CONCLUSIONS Combination chemotherapy is beneficial in some patients in whom immune thrombocytopenia is refractory to corticosteroids and splenectomy.

2-Chlorodeoxyadenosine: A Newer Purine Analog Active in the Treatment of Indolent Lymphoid Malignancies

2-Chlorodeoxyadenosine ([2-CdA], cladribine; Leustatin, Ortho Biotech, Raritan, New Jersey), along with fludarabine [1] and 2-deoxycoformycin [2], is a newer purine analog with major activity in the treatment of indolent lymphoid malignancies. Fludarabine (Fludara, Berlex Laboratories, Alameda, California) is approved by the Food and Drug Administration for the treatment of patients with chronic lymphocytic leukemia who are refractory to alkylating agents [3], 2-deoxycoformycin (Nipent, Parke Davis; Morris Plains, New Jersey) for the treatment of interferon-refractory hairy cell leukemia, and 2-CdA for patients with untreated or interferon-refractory hairy cell leukemia. The development of 2-CdA emerged from an improved understanding of the mechanisms of lymphopenia in adenosine deaminase-deficient children with severe combined immunodeficiency disease. We review the development, structure, mechanism of action, pharmacologic features, and the clinical trial results of this important new chemotherapeutic agent. Lessons from Adenosine Deaminase Deficiency In 1972, Giblett and colleagues [4] made the serendipitous but seminal observation that some infants with severe combined immunodeficiency disease were adenosine deaminase deficient. Cohen and colleagues [5] later established the relation between the intracellular accumulation of deoxyribonucleotides (resulting from adenosine deaminase deficiency) and lymphocytotoxicity. Carson and colleagues [6] evaluated a panel of purine deoxynucleosides synthesized to be resistant to deamination by adenosine deaminase for toxicity in vitro and identified 2-CdA as the most potent. 2-Chlorodeoxyadenosine induces a lymphopenic state, similar to that seen in adenosine deaminase deficiency, by resisting deamination and thereby accumulating in its triphosphate form with resultant lymphocytotoxicity. Structure and Synthesis 2-Chlorodeoxyadenosine is a deoxyadenosine analog, consisting of substitution of a chlorine atom for the hydrogen atom at the 2-position of the purine ring (Figure 1). It was first synthesized by Christensen and colleagues [7], using direct fusion alkylation of 2,6-dichloropurine. Later, Carson and colleagues [6] synthesized 2-CdA from 2-chloroadenine and thymidine using a transdeoxyribosylase from Lactobacillus helveticus. The drug in commercial use today is synthesized nonenzymatically using a sodium salt glycosylation procedure. Figure 1. Molecular structures of deoxyadenosine and 2-chlorodeoxyadenosine. Mechanisms of Action Adenosine deaminase catalyzes the irreversible deamination of deoxyadenosine to deoxyinosine (Figure 2). Deoxycytidine kinase phosphorylates purine deoxyribonucleotides, whereas 5-nucleotidase dephosphorylates them. Lymphocytes have high deoxycytidine kinase to 5-nucleotidase ratios, favoring triphosphate formation [8] and making them ideal target cells for 2-CdA. Figure 2. Deoxyadenosine metabolism. d. adenosine DCK NT d. AMP d. ADP d. ATP ADA d. adenosine d. inosine PNP XO 2-Chlorodeoxyadenosine enters the cell through an efficient transport system and is phosphorylated by deoxycytidine kinase. 2-Chlorodeoxyadenosine triphosphate is a potent inhibitor of ribonucleotide reductase and DNA polymerase- (Figure 3). 2-Chlorodeoxyadenosine triphosphate accumulation also depletes the intracellular pool of deoxynucleotides [9]. In actively dividing cells, DNA synthesis is then impaired by the preferential use of 2-chlorodeoxyadenosine triphosphate by DNA polymerase and the retardation of DNA chain elongation [10]. Figure 3. 2-Chlorodeoxyadenosine mechanism of action. 2-CdA ADA DCK 5-NT 2-CdAMP 2-CdADP 2-CdATP RNR NAD ATP 2-Chlorodeoxyadenosine is unique compared with traditional antimetabolites in being equally active against both dividing and resting cells [11, 12]. A different mechanism of action must therefore operate in resting cells because ribonucleotide reductase is only expressed at low levels. The DNA strand breaks that gradually accumulate with time activate two enzyme systems: poly-(ADP-ribose) polymerase-consuming nicotinamide adenine dinucleotide and adenosine triphosphate [12, 13] and a Ca++/Mg ++-dependent endonuclease that produces double-stranded DNA breaks at internucleosomal regions [14]. The cleavage of DNA into oligonucleosomal fragments follows, which is the hallmark of apoptosis, a form of programmed cell death [15-17]. Apoptosis Distinct from necrosis, apoptosis is a physiologic mechanism of cell death [18]. It is the mechanism by which senescent or abnormal cells that could interfere with organ function or develop into cancer are removed. Morphologically, apoptosis is characterized by compaction of chromatin against the nuclear membrane, cell shrinkage, and nuclear and cytoplasmic budding to form membrane-bound fragments, called apoptosis bodies, which are phagocytosed by adjacent cells or macrophages [17]. This process is completed in the absence of inflammatory changes. The tendency of a cancer cell to undergo apoptosis may determine the sensitivity of tumors with low growth fractions to chemotherapy. Indolent lymphoid tumors have high expression of the bcl-2 oncogene, known to enhance cell survival through its interference with apoptosis [19]. The induction of apoptosis by 2-CdA stimulates even greater interest in this agent for potential use in these bcl-2 expressing lymphoid malignancies. A possible relation between the expression of bcl-2 and susceptibility of the malignant cell to 2-CdA is under study. Preclinical Studies and Pharmacologic Features Preclinical studies showed that both B- and T-lymphoblastoid cell lines were sensitive to 2-CdA but that T-lymphoblastoid cell lines were more vulnerable [6]. Clinically, this difference is not apparent, and, in fact, B- lymphocyte-derived disorders are highly responsive. Prolonged exposure of resting peripheral blood lymphocytes to 2-CdA in vitro resulted in greater lymphocytotoxicity than did brief incubations [20], which led to the selection of a continuous intravenous infusion schedule for the initial clinical trials. The single 50% lethal dose of 2-CdA given intraperitoneally to mice was 150 mg/kg body weight and with daily administration for 5 days, the 50% lethal dose was 100 mg/kg [21]. 2-Chlorodeoxyadenosine prolonged the life of mice with L1210 leukemia [6]. Doses of 1 mg/kg given by continuous intravenous infusion to monkeys for 7 days caused severe diarrhea and granulocytopenia. 2-Chlorodeoxyadenosine is cleared by mammalian kidneys, probably secreted through the renal organic cation carrier system, and its elimination is according to a two-compartment model, with and -half-lives of 35 minutes and 6.7 hours, respectively [22]. Plasma 2-CdA concentrations of 20 to 30 nmol in patients with lymphoid malignancies were achieved with the standard infusion dose of 0.1 mg/kg per day by continuous infusion, which exceeds the 50% inhibition of growth for some human malignant lymphoblast cell lines incubated with 2-CdA in vitro [20]. A bolus method of 2-CdA administration was developed based on pharmacokinetic studies showing high concentrations and prolonged intracellular retention of 2-chlorodeoxyribonucleotides in chronic lymphocytic leukemia [23]. This method of drug delivery was devised to facilitate the outpatient administration of 2-CdA and to avoid the need for central catheters and infusion devices [24]. The bioavailability of 2-CdA given subcutaneously is 100% and, when administered orally, is 50%, although there are considerable differences among patients. Oral absorption is not enhanced by suppression of gastric acid [25]. 2-Chlorodeoxyadenosine penetrates the cerebrospinal fluid [26] with levels that are 25% of the plasma levels [27]. Clinical StudiesPhase 1 2-Chlorodeoxyadenosine dose-escalation studies showed myelosuppression, with considerable hematopoietic stem cell toxicity to be dose limiting. A maximum tolerated dose of 0.1 mg/kg per day for 7 days by continuous infusion (using the conversion factor of 40, 0.1 mg/kg is equivalent to 4 mg/m2 [28]) was established and was associated with a 25% incidence of myelosuppression [20]. Single courses of the drug at this dose caused transient marrow suppression with granulocytopenia and thrombocytopenia, especially in patients who were pancytopenic before the start of 2-CdA therapy. When repeated courses of 2-CdA were administered, cumulative thrombocytopenia became the limiting toxicity in 20% to 30% of patients, which persisted in some patients for more than 6 months. At this dose, no nausea, vomiting, alopecia, nephrotoxicity, hepatotoxicity, pulmonary and cardiac toxicity, or neurotoxicity was observed. Severe and sometimes irreversible nephrotoxicity and neurotoxicity with paresis were encountered when 2-CdA was administered at 0.4 to 0.5 mg/kg (16 to 20 mg/m2) per day for 7 to 14 days by continuous infusion in combination with high-dose cyclophosphamide and total body irradiation in preparation for allogeneic bone marrow transplantation. The contribution of 2-CdA compared with total body irradiation or high-dose cyclophosphamide in conjunction with the 2-CdA to these toxicities is unclear. In the initial studies, the actual dose of 2-CdA administered to patients was 0.09 mg/kg per day because doses were standardized using the extinction coefficient of chloroadenine, which proved to be slightly lower than that of 2-CdA [29]. Subsequently, all patients received 0.1 mg/kg per day because of synthesis and formulation changes, representing most patients treated in the clinical development of this drug. The maximum tolerated dose for 2-CdA delivered as a 7-day intravenous infusion to patients with nonhematologic malignancies was also 0.1 mg/kg per day. Neurologic events occurred in two patients, both with malignant melanoma, one treated with 0.15 mg/kg per day of 2-CdA and the other with 0.2 mg/kg per day. A direct neurotoxic role for 2-CdA was not absolutely established because of other associated conditio

A Phase 2 Study of Rituximab in Combination with Recombinant Interleukin-2 for Rituximab-Refractory Indolent Non-Hodgkin's Lymphoma

Purpose: The incidence of non-Hodgkins lymphoma (NHL), the fifth most common malignancy in the United States, has increased over 70% in the last 30 years. Fifty percent to 75% of patients with low-grade or follicular NHL respond to rituximab therapy. However, responses are generally of limited duration, and complete responses are rare. Preclinical work suggests that human recombinant interleukin-2 (rIL-2; aldesleukin, Proleukin) enhances rituximab efficacy. Antibody-dependent cellular cytotoxicity (ADCC) is an important mechanism of action of rituximab. rIL-2 induces expansion and activation of Fc receptor (FcR)–bearing cells, thereby enhancing ADCC. Therefore, a large, multicenter phase 2 trial to assess the effects of rIL-2 on rituximab therapy in patients with rituxumab-refractory low-grade NHL was conducted. Experimental Design: The combination of rituximab and rIL-2 was studied in 57 patients with rituximab-refractory low-grade NHL (i.e., patients must have received a single-agent course of rituximab and showed no tumor response, or had a response lasting <6 months). I.V. rituximab was given at 375 mg/m2 (weeks 1-4). S.C. rIL-2 was given thrice a week at 14 MIU (weeks 2-5) and at 10 MIU (weeks 6-9). Results: Rituximab plus rIL-2 combination therapy was safe and generally well tolerated, but responses were low. Fifty-seven patients were enrolled with 54 evaluable for response; however, only five responses (one complete and four partial) were observed. Correlative data indicate that rIL-2 expanded FcR-bearing cells and enhanced ADCC. However, other factors, such as FcγR polymorphisms in patients refractory to single-agent rituxumab and heterogeneous tumor biology, may have influenced the lack of clinical efficacy seen with this combination therapy. Conclusions: rIL-2 expands FcR-bearing cellular subsets in vivo and enhances in vitro ADCC of rituxumab. However, these findings do not directly translate into meaningful clinical benefit for patients with rituxumab-refractory NHL.

Complete Remissions in Hairy Cell Leukemia with 2-Chlorodeoxyadenosine after Failure with 2-Deoxycoformycin

Hairy cell leukemia, or leukemic reticuloendotheliosis, is an uncommon chronic B-cell lymphoproliferative disorder [1]. Patients, often elderly men, have pancytopenia, splenomegaly, or recurrent infections. The defining features of hairy cell leukemia are the presence of circulating mononuclear cells with prominent cytoplasmic projections and their characteristic pattern of infiltration in the bone marrow and spleen. 2-Chlorodeoxyadenosine (2-CdA), a purine substrate analog resistant to the action of adenosine deaminase, has major activity in indolent lymphoid neoplasms [2-5], especially hairy cell leukemia [6-8]. A single course of 2-CdA administered by continuous intravenous infusion for 7 days induces lasting complete remissions in most patients with hairy cell leukemia, with a favorable toxicity profile [6, 7]. 2-Deoxycoformycin (DCF), a natural product isolated from the culture broth of Streptomyces antibioticus, is a tight-binding inhibitor of adenosine deaminase. It is also an active agent in the treatment of hairy cell leukemia, inducing complete and long-lasting responses [9-11]. Given the structural similarities of DCF and 2-CdA and understanding that they affect the same enzyme pathway, we treated five patients with hairy cell leukemia resistant to or intolerant of DCF with 2-CdA to determine the presence or absence of cross-resistance and the safety of such treatment. Methods Eligibility Criteria Patients resistant to or intolerant of DCF therapy with active hairy cell leukemia, morphologically confirmed on a bone marrow examination, were eligible for 2-CdA treatment. Resistance to DCF was defined as primary refractoriness to DCF administration or relapse after a partial response lasting less than 12 months. Patients intolerant to DCF had experienced life-threatening side effects with DCF therapy. Patients had to have an absolute neutrophil count less than 1.0 109/L, a hemoglobin concentration less than 100 g/L, or a platelet count less than 100 109/L to be entered into the study. All patients had to have discontinued -interferon or DCF therapy at least 3 months before the study and have no evidence of active infection. In addition, all patients had to be older than 18 years, have adequate renal (serum creatinine concentration less than 180 mol/L) and hepatic function (bilirubin, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase) less than two times normal, and be available for follow-up evaluation. Written informed consent was obtained and the study was approved by our institutional review board. Drug Formulation 2-Chlorodeoxyadenosine was synthesized and purified as previously described [12] or supplied by Ortho Pharmaceutical (Raritan, New Jersey) and recrystallized before use. 2-Chlorodeoxyadenosine was supplied to the pharmacy as a 0.1% solution (1 mg/mL) of pyrogen-free 2-CdA in sterile 0.9% NaCl. For outpatients using an infusional pump device (Pharmacia Deltec CADD-PCA Infusion Pump; St. Paul, Minnesota), the desired dosage of 0.10 mg/kg per day was added to the 0.9% NaCl solution to make a total volume (drug plus diluent) of 100 mL; for inpatients, the same dosage was added daily to 500 mL of 0.9% NaCl. Study Design All patients received a single course of 0.10 mg/kg body weight of 2-CdA by continuous intravenous infusion for 7 days. For outpatients, this was administered through a peripherally inserted central venous catheter using an infusion pump. Inpatients were admitted to our General Clinical Research Center and the drug was infused using peripheral venous access. Hematologic and nonhematologic toxic responses were monitored according to standard criteria [13]. For clinically significant anemia or thrombocytopenia, packed red blood cells or platelet transfusional support or both were administered. For a temperature greater than 38.5 C, patients were admitted and empiric broad-spectrum antibiotics were initiated. Before therapy was begun, all patients had complete histories taken and physical examinations, reviews of their bone marrow histologic findings, reviews of splenic and lymph node tissue when available, bone marrow and peripheral blood tartrate-resistant acid phosphatase stains, complete blood counts with differential counts, 24-chemical blood chemistry panels, and imaging of the chest, abdomen, and pelvis by computed axial tomography. Serial peripheral blood lymphocyte, flow cytometric examination was done when possible. During therapy and on subsequent follow-up, all patients had a physical examination and a complete blood count with differential counts daily until the absolute neutrophil count was greater than 1 109/L and the platelet count was greater than 20 109/L, then weekly until the blood counts returned to normal. Patients then were followed at 3-month intervals. Bilateral bone marrow aspiration and biopsies, together with tartrate-resistant acid phosphatase stains, were performed at 3, 6, and 12 months, and yearly thereafter, and were reviewed at Scripps Clinic and Research Foundation. Computed tomographic scans were repeated during periods of maximum response. Response Criteria Complete remission was defined as the absence of discernible hairy cells in the bone marrow aspirate and biopsy; the presence of tartrate-resistant acid phosphatase-positive cells lacking typical hairy cell morphologic features did not preclude a complete remission designation. The absolute neutrophil count was 1.5 109/L or greater, the hemoglobin concentration was 120 g/L or greater, and the platelet count was 100 109/L or greater. Neither splenomegaly nor lymphadenopathy were evident on physical examination or on computed tomographic scan. Partial remission required a reduction of 50% or more in the absolute count of hairy cells in the peripheral blood and bone marrow and a similar decrement in the size of splenomegaly or lymphadenopathy or both by examination and imaging studies, when present. In addition, there had to be an increase in granulocytes, hemoglobin, or platelet count of at least 50% of the deviation from normal of the pretreatment value. All other responses were judged to be in the no response category. Results Patient Characteristics Five patients, four men and one woman, with a median age of 55 years (range, 44 to 57 years), entered the study (Table 1). All patient biopsy specimens stained positively with tartrate-resistant acid phosphatase. All patients had received previous interferon and DCF therapy. Two patients had also undergone splenectomy, and one of these two patients (patient 5) also had received abdominal irradiation to overcome biliary obstruction from massively enlarged periportal lymph nodes. Of the five patients, four had obtained a response during interferon therapy, one had a complete response, and three had partial responses. The median response duration following interferon therapy was 14 months, ranging from 4 to 18 months. Table 1. Pretreatment Patient Characteristics and Previous Therapy All five patients had received DCF at 4 mg/m2 body surface area every other week for a median of 5 doses (range, 2 to 23 doses) (see Table 1). Patient 1 achieved a partial response of 9 months duration following 23 doses of DCF and was therefore designated as DCF resistant. Therapy with DCF was complicated by dermatomal herpes zoster. In patient 2, DCF therapy was discontinued after three doses because his therapy was complicated by pancytopenia, fever, and a subendocardial infarction. Because of these life-threatening toxicities on DCF, he was classified as being DCF intolerant. In patient 3, DCF therapy was withdrawn after two doses because of profound pancytopenia, an associated fever, and a protracted hospital stay; she was designated DCF intolerant. Patient 4 had no response to five doses of DCF and was considered to be primary DCF resistant. Treatment was complicated by nausea, vomiting, and culture-negative pneumonitis requiring the empiric use of amphotericin B. Patient 5, who had previously demonstrated responsiveness to splenectomy and interferon, was refractory to eight doses of DCF and was also considered to be primary DCF resistant. Dermatomal herpes zoster developed in patient 5 during DCF therapy. The median duration from diagnosis of hairy cell leukemia to the initiation of 2-CdA was 3.5 years (range, 2.3 to 14.5 years). The median duration from the completion of DCF therapy to the initiation of 2-CdA therapy was 1 year (range, 0.5 to 2 years). Peripheral Blood Hematologic Changes after Treatment The median leukocyte count at the initiation of 2-CdA therapy was 2.0 109/L (range, 0.8 to 21.8 109/L), at the nadir it was 0.4 10 (9/L) (range, 0.2 to 0.8 109/L), and after 2-CdA treatment it increased to 3.8 109/L (range, 2.5 to 8.1 109/L) (Table 2). Associated with these changes in the total leukocyte count was a median pretreatment absolute neutrophil count of 0.56 109/L (range, 0.20 to 1.01 109/L), a nadir of 0.35 109/L (range, 0.06 to 0.58 109/L), and a value after treatment of 2.73 109/L (range, 0.68 to 2.95 109/L). Table 2. Peripheral Hematologic Values Following a Single Infusion of 2-CdA The median hemoglobin concentration before treatment was 112 g/L (range, 60 to 134 g/L), the median hemoglobin nadir was 94 g/dL (range, 84 to 108 g/L), and the median hemoglobin after treatment increased to 140 g/L (range, 105 to 155 g/L). The median platelet count before treatment was 55 109/L (range, 12 to 95 109/L), the median platelet nadir was 54 109/L (range, 16 to 80 109/L), and the median platelet count after treatment increased to 123 109/L (range, 100 to 207 109/L) (see Table 2). Responses Of five patients, four (80%) obtained complete responses and one patient (20%) achieved a partial response. Patients 2 and 3, intolerant of DCF, both achieved complete responses. Patient 2 had fewer than 1% tartrate-resistant acid phosphatase-positive cells on follow-up bone marrow examination without morphologic evidence of hairy cell leukem

2-Chlorodeoxyadenosine-Induced Complete Remissions in Langerhans-Cell Histiocytosis

Langerhans-cell histiocytosis results from the proliferation and accumulation of tissue histiocytes, clinically manifested as osteolytic lesions, hypothalamic insufficiency, and seborrheic and vesiculopustular lesions on the scalp, perineum, rectum, and vulva [1]. Treatment has been palliative and includes corticosteroids, alkylating agents, antimetabolites, vinca alkaloids, and irradiation [2]. Combination chemotherapy offers no advantage over the use of single agents and is associated with greater toxicity. 2-Chlorodeoxyadenosine (2-CdA) (cladribine, Leustatin [Ortho Biotech, Raritan, New Jersey]), a purine analog with activity in indolent lymphoproliferative disorders and myeloid leukemias [3, 4], is potently toxic to monocytes in vitro [5]. Because tissue histiocytes are derived from the same stem cells as circulating monocytes, 2-CdA was a rational therapeutic option [6]. We therefore administered 2-CdA to three patients with Langerhans-cell histiocytosis. Methods Patients were required to have a histologic diagnosis of Langerhans-cell histiocytosis and measurable disease. 2-Chlorodeoxyadenosine was supplied by Ortho Biotech and was administered every 28 to 35 days until maximum response or prohibitive toxicity. A complete response was defined as the absence of disease as proven by physical examination and imaging studies. Skin lesions did not require repeat biopsy to document histologic resolution. A partial response was defined as a reduction by more than 50% of all measurable disease for more than 1 month. Any response less than partial was designated as no response. Standard criteria of the Eastern Cooperative Oncology Group were used for the evaluation of toxicity [7]. Results Patient 1 A 33-year-old woman presented at age 15 years with polyuria and polydipsia from diabetes insipidus and later developed vesiculopustular lesions of her gingiva, scalp, and vagina that were histologically confirmed as Langerhans-cell histiocytosis. High-dose steroids induced a brief, partial response. After delivering a normal infant by cesarean section, she developed painful vaginal ulcers that were treated with irradiation. The cutaneous lesions were treated with vinblastine, which initially achieved a partial response; later, however, the lesions became refractory. Oral VP-16, vincristine, cyclophosphamide, and methotrexate were administered without benefit. When first treated with 2-CdA, she had numerous 3- to 4-mm vesiculopustular lesions and shallow ulcers of her scalp, buccal mucosa, vagina, and external auditory canals (Figure 1). Her medications were intranasal desmopressin, 0.1 mL twice a day, and synthroid replacement. Before treatment, she had normal liver function test results, a leukocyte count of 5.5 109/L with a normal differential, a hemoglobin concentration of 123 g/L, and a platelet count of 202 109/L. The marrow was normocellular, and computed tomographic (CT) scans of the abdomen and bone survey were normal. She was assessed as having good-risk disease [8] (stage II as designated by Lavin and Osband [9]). Four courses of 2-CdA at 0.7 mg/kg of body weight per course given over 7 days by continuous intravenous infusion were administered. The second 2-CdA course was delayed by dermatomal herpes zoster and was later complicated by transient grade 3 neutropenia (absolute neutrophil count, <0.5 to 1.0 109/L). The patient achieved a complete response after treatment and has remained in unmaintained complete remission for more than 23 months. Follow-up blood counts showed a leukocyte count of 4.3 109/L with a normal differential, a hemoglobin concentration of 118 g/L, and a platelet count of 149 109/L. Figure 1. Figure 1. Langerhans-cell histiocytosis lesions of the scalp (A), skin (B), and gingiva (C) in patient 1 before administration of 2-CdA therapy. During each course of 2-CdA, blood monocytes completely disappeared. The median absolute monocyte count before treatment was 0.28 109/L (range, 0.09 to 0.38 109/L); after 48 hours of 2-CdA treatment, the count was 0.09 109/L (range, 0.05 to 0.38 109/L). On day 7, the monocyte count was 0.0 109/L during all four courses. A peripheral blood immunophenotypic analysis done after the second 2-CdA course showed a CD4 cell count of 137 cells/mL and a CD8 cell count of 76 cells/mL (CD4/CD8 ratio, 1.61). After three courses of 2-CdA, the CD4 cell count was 175 cells/mL and the CD8 cell count was 464 cells/mL (CD4/CD8 ratio, 0.38). Six months after the fourth course of 2-CdA, the CD4 count was 202 cells/mL, and the CD8 cell count was 307 cells/mL (CD4/CD8 ratio, 0.66). After treatment, the patient became pregnant and delivered a normal 5 1/2-pound baby girl by cesarean section. Twelve months postpartum, she remains free of disease. Patient 2 A 57-year-old man presented with a 2-year history of erythematous patches and scattered papular lesions involving his scalp, external auditory canals, axillae, and scrotal areas without associated lymphadenopathy or hepatosplenomegaly (Figure 2). He received a brief course of high-dose prednisone without response. Biopsy specimens of these skin lesions confirmed Langerhans-cell histiocytosis and showed positivity for the S-100 protein immunohistochemical stain. Intracytoplasmic Birbeck granules were identified on electron microscopy. Before treatment, the leukocyte count was 3.1 109/L, the absolute neutrophil count was 1.3 109/L, the hemoglobin concentration was 146 g/L, and the platelet count was 147 109/L. The bone marrow, chest radiograph, bone scan, bone survey, and CT scan of the abdomen were all normal. He was staged as poor risk because of the neutropenia [8] (Lavin and Osbands stage III [9]). Figure 2. Figure 2. The scalp of patient 2 before treatment (A) and the inguinal cutaneous lesions of patient 2 before and after treatment (B and C, respectively). Two courses of 2-CdA at 0.7 mg/kg per course given over 7 days by continuous intravenous infusion were administered. The second course was delayed because of protracted grade 3 neutropenia and mild thrombocytopenia. Three months after the last course of 2-CdA, all lesions resolved. The patient has remained in complete remission for more than 15 months (Figure 2). On follow-up, the leukocyte count was 2.6 109/L, the absolute neutrophil count was 0.8 109/L, the hemoglobin concentration was 134 g/L, and the platelet count was 100 109/L. Patient 3 A 51-year-old woman had a 10-year history of cutaneous involvement by Langerhans-cell histiocytosis. She had extensive nonpruritic erythematous papular lesions involving her face, chest, extremities, and perineum. A partial response lasting 3 months was achieved after a course of vinblastine. At relapse the patient was retreated with vinblastine, which induced a second brief, partial response. Later, psoralen plus ultraviolet A exposure were administered without benefit. Because of symptomatic and progressive cutaneous lesions, the patient was treated with 2-CdA at 0.7 mg/kg per course, given over 5 days by 2-hour intravenous infusions. She was assessed as having good-risk disease because of the absence of organ dysfunction [8] (Lavin and Osbands stage II [9]). The patient developed transient grade 3 neutropenia within 1 week of completing the course of 2-CdA therapy that fully resolved by week 2. One month after her first course of 2-CdA, her symptoms and skin lesions improved, and a complete clinical remission was achieved at 2 months. She received a second course of 2-CdA without complications, and her skin biopsy-confirmed complete remission has continued for more than 5 months. Discussion Langerhans cells are found in various tissues and belong to a class of dendritic histiocytes, the major function of which is antigen presentation to lymphocytes. These cells and the histiocytes of the mononuclear-phagocyte system are derived from marrow stem cells. However, tissue macrophages can proliferate independently of marrow stimulation [10]. 2-Chlorodeoxyadenosine, an antimetabolite that is uniquely able to destroy resting and dividing cells with equal efficacy [11] and is potently toxic to monocytes [5], offers advantages in treating monocyte-derived neoplasms and chronic inflammatory conditions. All three patients achieved complete remissions after 2-CdA therapy. Patient 1, refractory to vinblastine and other single-agent chemotherapeutic agents, remains in a long-lasting complete remission after four courses of 2-CdA. Patient 2, refractory to high-dose steroids, achieved a durable, unmaintained complete remission after two courses of 2-CdA. Patient 3, previously responsive to vinblastine, achieved a complete remission after a single course of 2-CdA. Therapy in patient 1 was complicated by reversible myelosuppression and dermatomal herpes zoster. At 6 months, there appeared to be CD4 and CD8 lymphocyte subset recovery was seen that was similar to the tendency reported in hairy cell leukemia [12]. In patient 2, protracted myelosuppression was the principal toxicity of 2-CdA therapy, but CD4 and CD8 lymphocyte subsets were not measured. In patient 3, therapy was complicated only by transient, asymptomatic neutropenia. The activity of 2-CdA against monocytes was not predicted from congenital adenosine deaminase deficiency, in which there is only an absence or immunologic incompetence of lymphocytes without monocytopenia. Additionally, 2-deoxycoformycin, a tight-binding inhibitor of adenosine deaminase that in some ways simulates the situation of severe combined immunodeficiency disease and has a similar spectrum of activity against lymphoid malignancies as that of 2-CdA, is not toxic toward monocytes [13]. The mechanism of response to 2-CdA in Langerhans-cell histiocytosis has not been elucidated but may involve direct cytotoxicity to monocytes or the putative Langerhans cell, or may be mediated through its T-cell immunosuppressive effects [12]. The potential activity of 2-CdA in the treatment of histiocytic diseases is encouraging an

2-Chlorodeoxyadenosine dose escalation in nonhematologic malignancies.

PURPOSE We performed a dose-escalation study of 2-chlorodeoxyadenosine (2-CdA) in solid tumors to determine the maximum-tolerated dose (MTD) and define its toxicity profile at higher doses. PATIENTS AND METHODS Twenty-one patients, seven with malignant astrocytoma, twelve with metastatic melanoma, and two with metastatic hypernephroma, were enrolled onto the study. Patients were entered onto cohorts that received 0.10, 0.15, or 0.20 mg/kg/d of 2-CdA by continuous intravenous infusion for 7 days every 28 days. 2-CdA levels were determined by radioimmunoassay. In tumor tissue samples, deoxycytidine kinase (dCK) levels were measured by both enzyme activity and immunoreactive protein analysis. RESULTS Of seven patients treated with 2-CdA at 0.1 mg/kg/d, one experienced grade 3 or 4 myelotoxicity. Of 11 patients treated at 0.15 mg/kg/d, four experienced myelotoxicity, two after a single course of 2-CdA. All three patients who received 2-CdA at 0.2 mg/kg/d experienced myelosuppression. Neurologic events occurred in two patients, both with malignant melanoma. Two of seven patients (28.6%) with astrocytomas obtained partial responses with a median duration of 8 months. 2-CdA penetrated the blood-brain barrier. An association was found between dCK levels as measured by enzymatic activity and immunoreactive proteins, but this did not correlate with 2-CdA tumor responsiveness. CONCLUSION The MTD for 2-CdA delivered as a 7-day intravenous infusion in patients with nonhematologic malignancies was determined to be 0.1 mg/kg/d, the same as the MTD for patients with hematologic malignancies. There was no clinical correlation with dCK expression and response to 2-CdA. The responses noted in patients with malignant astrocytoma warrant further phase II study.

Pharmacokinetic study of oral and bolus intravenous 2-chlorodeoxyadenosine in patients with malignancy.

PURPOSE This study was designed to evaluate the absolute bioavailability (F value) of 2-chlorodeoxyadenosine (cladribine; 2-CdA) after multiple oral administrations, and the intersubject variability after oral and 2-hour intravenous (IV) administration schedules in patients with malignancy. PATIENTS AND METHODS Patients with advanced malignancies were eligible. There were two treatment cycles; during cycle 1, patients received 2-CdA solution at 0.28 mg/kg/d orally under fasting conditions for 5 consecutive days concomitantly with omeprazole, and 4 weeks later during cycle 2 patients received 2-CdA as a 2-hour IV infusion of 0.14 mg/kg/d for 5 consecutive days. Serial blood samples for 2-CdA plasma levels were obtained after drug administrations on days 1 and 5 during each treatment cycle. RESULTS Ten patients completed cycles 1 and 2. The F value of oral 2-CdA measured on days 1 and 5 was 37.2% and 36.7%, respectively. For both oral and IV multiple administrations, there was no significant accumulation in maximum concentration (Cmax), and the intersubject variabilities (coefficient of variation [CV], approximately 40%) in Cmax and area under the concentration-time curve from 0 to 24 hours [AUC(0-24)] values were comparable for both routes on days 1 and 5. A three-compartment open model was applied to the plasma concentration data after oral and IV administrations and resulted in good agreement between observed and simulated concentration-time profiles. Neutropenia was the principal adverse event observed when 2-CdA was administered orally and IV. CONCLUSION The F value of 2-CdA after oral administration was approximately 37% and there were no cumulative differences in bioavailability observed on multiple dosing of the drug. The absorption and disposition characteristics of oral 2-CdA were linear and predictable with this dosing regimen.

Major activity of cladribine in patients with de novo B-cell prolymphocytic leukemia.

PURPOSE De novo B-cell prolymphocytic leukemia (B-PLL) is a distinct clinicopathologic entity usually characterized by marked lymphocytosis, massive splenomegaly, an aggressive course, and refractoriness to therapy. Cladribine (2-chlorodeoxyadenosine [2-CdA]; Ortho Biotech, Raritan, NJ) is a newer purine analog with potent activity against indolent lymphoproliferative disorders. PATIENTS AND METHODS We treated eight patients with cladribine 0.1 mg/kg/d for 7 days by continuous infusion or 0.14 mg/kg/d over 2 hours for 5 days, every 28 to 35 days, for a median of three courses (range, two to five). There were five men and three women, with a median age of 62 years and a median pretreatment duration of 6 months; four patients were previously untreated. RESULTS All eight patients were assessable: five achieved a complete response with a median response duration of 14 months (range, 1+ to 55+), and three achieved a partial response with a median duration of 3 months (range, 1 to 3). Of four patients who achieved a complete response and in whom a peripheral-blood immunophenotypic analysis was performed, two had no circulating B-PLL cells and one had no residual disease on Southern blot analysis. Myelosuppression and infection were the major toxicities: three patients developed grade 3 or 4 myelosuppression, four had bacterial infections, and two had herpes zoster infections. CONCLUSION In this small study of patients with de novo B-PLL, cladribine was an active agent that induced a high overall and complete response rate. These results require confirmation in larger numbers of B-PLL patients.