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Vomiting associated with pentostatin and pentostatin plus alpha-interferon: unique pattern and potential mechanisms.

Pentostatin (2'-deoxycoformycin) is a unique antineoplastic agent that has proven valuable in the treatment of a number of lymphoid malignancies. Dose-limiting toxicities observed in clinical trials include central nervous system (CNS) effects and acute renal failure. Information regarding the incidence, duration, and severity of nausea and vomiting from published reports is conflicting and insufficient to provide recommendations for optimal supportive measures. We report the results of a phase I study where pentostatin was associated with a 20% incidence of vomiting following courses one and two (pentostatin alone). The third course of pentostatin administered concurrently with alpha interferon resulted in a 29% incidence of vomiting and by course four had increased to 50%. Grade of severity was similarly increased, and nausea and vomiting was the dose-limiting toxicity in 6 of 15 patients. Forty-two percent of all episodes of vomiting were delayed in onset (onset 24 hr after drug administration) and in over 80% of cases persisted for greater than 48 hr in duration. Potential mechanisms that may account for these findings, as well as recommendations regarding antiemetic therapy are provided.

Adult↗

Chemical stability of pentostatin (NSC-218321), a cytotoxic and immunosuppressant agent.

Pentostatin, an unusual nucleoside of natural origin, has been used for the treatment of hairy cell leukemia, as an immunosuppressant agent, and as an inhibitor of adenosine deaminase. The studies of the physicochemical properties and solution stability of pentostatin are important to the development of a parenteral formulation for extensive preclinical and clinical testing. Pentostatin displayed apparent pKa values at 25 +/- 0.1 degree C and ionic strength of 0.15 M of 2.03 +/- 0.03 and 5.57 +/- 0.14 (spectrophotometric) and 5.50 +/- 0.02 (potentiometric) for N1 and the amidine nitrogen in the seven-membered ring, respectively, which are the most likely protonation sites. The rates of degradation of pentostatin were determined as a function of pH, buffer concentration, and temperature. In the pH range 1.0-4.0, pentostatin undergoes acid-catalyzed glycosidic cleavage leading to the formation of the base compound, and 2-deoxyribose. A carbonium ion mechanism in which C-N bond cleavage was the rate-determining step was consistent with the data. In the pH range 6.5-10.5, the imine bond at C5 position in pentostatin is hydrolyzed to form the corresponding formamide. Pentostatin hydrolysis in this pH range was independent of pH. At pH greater than 11, pentostatin decomposes to nonchromophoric products probably through multiple-step base-catalyzed hydrolytic mechanisms. Pentostatin appears to be quite stable after reconstitution of a lyophilized experimental dosage form. Care must be taken if pentostatin is extensively diluted with 5% dextrose in water, as pentostatin stability is compromised at pH values less than 5.

Buffers↗

Long-term follow-up of patients with hairy cell leukaemia after treatment with pentostatin or cladribine.

We report the long-term follow-up results on two groups of patients with hairy cell leukaemia (HCL) treated with either pentostatin (deoxycoformycin) or cladribine (2-chlorodeoxyadenosine). 165 HCL patients received treatment with pentostatin (between 1986 and 1994), and 45 were treated with cladribine (between 1992 and 1997). Age and sex characteristics were similar in the two groups. 38 patients in the pentostatin group and 12 in the cladribine group were previously untreated. 22 patients in the cladribine group had received prior treatment with pentostatin; four were resistant, 17 had relapsed following partial (four) or complete (13) responses, and one was not evaluable for response. The response rates were the same in the two groups: 82% complete response (CR), 15% partial response (PR) for pentostatin and 84% CR, 16% PR for cladribine. Relapse rates were 24% for pentostatin and 29% for cladribine after median follow-up of 71 and 45 months respectively. At 45 months, however, the relapse rate for pentostatin was only 9.7%. We found a statistically significant difference in the disease-free interval (DFI) between the two groups suggesting that patients may relapse more quickly after cladribine. The majority of relapsed patients achieved second remissions following further therapy with either pentostatin or cladribine, with no evidence of cross resistance between the two agents. The 5-year survival for all patients was 97% and treatment- related toxicity was low. We conclude that both pentostatin and cladribine induce durable remissions in the majority of HCL patients. Longer follow-up is required to establish whether some patients are cured as there is no plateau in DFI, and which of these two agents may be the treatment of choice.

Adult↗

Pentostatin: an adenosine deaminase inhibitor for the treatment of hairy cell leukemia.

OBJECTIVE: To review the pharmacology, pharmacokinetics, adverse effects, and various dosage regimens of pentostatin, and to evaluate the role of pentostatin in the treatment of hairy cell leukemia (HCL). DATA IDENTIFICATION: Articles were identified via an English-language literature search of MEDLINE (1966-91) and an extensive search of bibliographies from identified articles. STUDY SELECTION: Human clinical trials and case reports were selected for evaluation. DATA EXTRACTION: The literature was assessed for quality, methodology, and outcome information. DATA SYNTHESIS: At dosages of 4 mg/m2 administered every other week for 6-9 months, pentostatin has been shown to successfully induce a complete response in 58-90 percent of patients and to produce a partial response in up to 30 percent of patients with HCL. The median time to achieve a response is 4.7 months. Long-term remissions of at least 14 months' duration have occurred in some patients. Compared with interferon alfa alone, total response rates are not significantly different when pentostatin and interferon alfa are used in combination. When dosed appropriately, pentostatin is generally well tolerated. Common adverse effects include nausea, vomiting, myelosuppression, fever, and infection. CONCLUSIONS: Pentostatin is a purine analog that inhibits adenosine deaminase, a key enzyme necessary for purine salvage. Pentostatin has received labeling approval for the treatment of HCL refractory to a minimum of three to six months of treatment with interferon alfa. Based on current data, pentostatin will be a useful addition to the therapeutic agents presently available to patients with HCL. Ongoing trials are evaluating the effectiveness of pentostatin as first-line therapy for patients with HCL.

Adenosine Deaminase Inhibitors↗

Randomized comparison of pentostatin versus interferon alfa-2a in previously untreated patients with hairy cell leukemia: an intergroup study.

PURPOSE: Therapy of hairy cell leukemia has markedly improved. Interferon alfa-2a and pentostatin are active agents. The National Cancer Institute organized an intergroup trial to compare these agents prospectively in untreated patients. METHODS: Patients were randomized to receive either interferon alfa-2a (3 x 10(6) U subcutaneously three times per week) or pentostatin (4 mg/m2 intravenously every 2 weeks). Patients who did not respond to initial treatment were crossed over. RESULTS: Of 356 patients on study, 313 were eligible. Among interferon patients, 17 of 159 (11%) achieved a confirmed complete remission and 60 of 159 (38%) had a confirmed complete or partial remission. Among pentostatin patients, 117 of 154 (76%) achieved a confirmed complete remission and 121 of 154 (79%) had a confirmed complete or partial remission. Additional patients achieved criteria for complete remission, but lacked confirmatory follow-up evaluation. Response rates were significantly higher (P < .0001) and relapse-free survival was significantly longer with pentostatin than interferon (P < .0001). The median follow-up duration is 57 months (range, 19 to 82). Myelosuppression was more frequent with pentostatin (P = .013). A multivariate logistic regression analysis of the confirmed complete remissions on pentostatin showed the following factors to be important for achieving a complete remission: high hemoglobin level (two-tailed P = .024), young age (P = .0085), and no or little splenomegaly (P = .0029). CONCLUSION: Both agents were well tolerated. Pentostatin produced higher response rates, and the responses were durable. Patient age and clinical status had an impact on outcome with pentostatin. Pentostatin is effective therapy for hairy cell leukemia.

Adult↗

Effect of adenosine deaminase inhibition with pentostatin on myocardial stunning in dogs.

Pentostatin (2-deoxycoformycin) is a potent inhibitor of adenosine deaminase and has been demonstrated to augment endogenous adenosine levels during regional and global myocardial ischemia. Based on the rationale that increasing endogenous adenosine during ischemia may be cardioprotective, the objective of this study was to determine if adenosine deaminase inhibition with pentostatin could improve postischemic contractile dysfunction (stunning) in open-chest anesthetized dogs. All animals underwent 15 min of coronary occlusion followed by 3 h of reperfusion preceded by an intravenous bolus of either 0.2 mg/kg of pentostatin (n = 8) or saline (n = 7). Sonomicrometers were placed in the ischemic area and were used to measure systolic wall thickening before, during, and after occlusion of the left anterior descending artery. Myocardial blood flow was measured with tracer labeled microspheres at baseline, 10 min of occlusion and at 1 h of reperfusion. Both groups were equally dyskinetic during occlusion (-21 +/- 5% of baseline thickening in the controls and -28 +/- 8% in the pentostatin group). The pentostatin group, however, demonstrated better contractile function at all time points during reperfusion, which was significantly different from the control group at 3 h of reperfusion. The improvement in regional function in the pentostatin group was not due to significant disparities in hemodynamic variables, size of the region at risk, or in collateral blood flow. These results indicate that pentostatin can ameliorate the severity of myocardial stunning, an effect we propose is due to increasing endogenous levels of adenosine during the ischemic interval. Although significant improvement was detected with pentostatin, the improvement was modest compared to controls, suggesting that the utility of inhibiting adenosine deaminase to modify regional mechanical stunning is limited.

Adenosine Deaminase Inhibitors↗

Long-term follow-up of remission duration, mortality, and second malignancies in hairy cell leukemia patients treated with pentostatin.

The nucleoside analogue, pentostatin, has demonstrated high complete response rates and long relapse-free survival times in patients with hairy cell leukemia, a disease that historically had been unresponsive to treatment. Long-term data on duration of overall survival and relapse-free survival and incidence of subsequent malignancies with this agent are lacking. Patients completing the treatment phase of a randomized, intergroup study who received pentostatin as an initial treatment or who crossed over after failure of interferon alpha were followed for survival, relapse, and diagnosis of subsequent malignancies. Two hundred forty-one patients treated with pentostatin as initial therapy (n = 154) or who crossed over after failure of interferon alpha (n = 87) were followed for a median duration of 9.3 years. Estimated 5- and 10-year survival rates (95% confidence interval) for all patients combined were 90% (87%-94%) and 81% (75%-86%), respectively. In the 173 patients with a confirmed complete response to pentostatin treatment, 5- and 10-year relapse-free survival rates were 85% (80%-91%) and 67% (58%-76%), respectively. Survival curves for patients initially treated with pentostatin and those crossed over were similar. Only 2 of 40 deaths were attributed to hairy cell leukemia. The mortality rate and incidence of subsequent malignancies were not higher than expected in the general population. Pentostatin is a highly effective regimen for hairy cell leukemia that produces durable complete responses. Subsequent malignancies do not appear to be increased with pentostatin treatment.

Adult↗

Activity of pentostatin (Nipent) in cutaneous T-cell lymphoma: single-agent and combination studies.

Cutaneous T-cell lymphoma (CTCL) comprises a constellation of diseases of malignant clonal T lymphocytes that present initially in the skin. Since biochemical studies of pentostatin suggested that T cells are more sensitive to the effects of inhibition of adenosine deaminase by purine analogs, early studies with pentostatin were conducted in patients with refractory T-cell neoplasms. Durable responses were reported in several patients on phase I studies. Of 94 CTCL patients treated on five phase II studies with single-agent pentostatin, the overall response rate was 40%, with a 7% complete response rate; the median time to progression ranged from 1.3 to 8.3 months. There was a trend toward improved response in patients with diffuse erythroderma or plaque disease. A phase II study combining pentostatin with intermittent high-dose interferon-alpha demonstrated a 41% overall response rate, with two complete responses, both in patients with Sézary syndrome and diffuse erythroderma Toxicities have been tolerable at doses of 4 to 5 mg/m2 administered weekly or for 3 consecutive days, with grade 3-4 hematologic toxicity in 31 patients, renal insufficiency in seven, nausea in 17, and conjunctivitis in three. In summary, pentostatin has demonstrated impressive activity in patients with advanced and refractory CTCL. Additional studies using pentostatin in earlier-stage CTCL or in combination with other active agents in advanced disease are warranted.

Adenosine Deaminase Inhibitors↗

Long term outcome of patients with hairy cell leukemia treated with pentostatin.

BACKGROUND: With the introduction of new drugs such as interferon-alpha (IFN) and purine analogs, the management of hairy cell leukemia (HCL) patients has changed. However, pentostatin has been found to produce higher complete remission rates than IFN. The current study was undertaken to investigate response and long term follow-up in HCL patients treated with pentostatin. METHODS: Between March 1989 and October 1996, 49 patients with HCL and 1 patient with a HCL variant were treated with pentostatin. Eighteen patients had received no prior therapy, 31 patients had received prior treatment with IFN, and 1 patient had received prior treatment with 2'-chlorodeoxyadenosine (2'CdA) and IFN. All patients except 1 were treated with a dose of 4 mg/m2 every 2 weeks. The median number of cycles was 12. RESULTS: The overall response rate was 96% (48 of 50 patients); 22 patients (44%) achieved a complete response, 18 patients (36%) achieved a good partial response (defined as residual bone marrow infiltration < 5%), 8 patients (16%) achieved a partial response, and 2 patients died. For a median follow-up of 33 months off therapy, there were 5 recurrences between 12-66 months; 3 of these patients were treated further with and responded to 2'CdA and 2 died of disease progression at 12 and 40 months, respectively. In addition, 3 patients died of unrelated causes (1 of very early infection, 1 of toxic death and another of cardiac arrest) comprising an overall death rate of 14% (7 of 50 patients). The overall survival rate was 86% for a median follow-up of 38 months (range, 8-105 months). Major side effects were febrile episodes, herpes zoster, nausea/emesis, and pancytopenia. CONCLUSIONS: This analysis confirms both the high remission rate and durable responses that may be achieved with pentostatin treatment in HCL patients. Although pentostatin is active, the risk of cytopenia and immunosuppression must be evaluated carefully.

Adult↗

A phase I trial of alpha-interferon in combination with pentostatin in hematologic malignancies.

Pentostatin, a novel inhibitor of adenosine deaminase, has shown activity in various lymphoid malignancies of both the T and B cell lineage. This agent has unique side effects and in general myelosuppression has been mild. Interferon has both antiviral and antineoplastic properties. This agent has shown activity in hairy cell leukemia, chronic granulocytic leukemia, low grade lymphoma, and myeloma. Side effects from interferon are in general dissimilar to those that have been seen with pentostatin and in particular myelosuppression has not been a major toxicity with low doses of interferon. This current trial explored the combination of pentostatin and interferon in hematologic malignancies. Fifteen patients were enrolled in this phase I trial at a fixed dose of pentostatin of 4 mg/m2 biweekly and interferon at doses of 0.5, 1, 2, or 4 million units/m2 of interferon. At the first three dose levels of interferon nausea and vomiting were the predominant toxicity and appeared to worsen with time on study. Fatigue also was seen at the lowest level of interferon and was severe enough to cause two individuals to discontinue the study medications. At higher dose levels of interferon, myelosuppression, nausea and vomiting, and fatigue were the predominant toxicities. One patient with hairy cell leukemia had a complete response and a second patient with T cell cutaneous lymphoma had a partial response which lasted for 6 to 7 weeks. The maximum tolerated dose of interferon with pentostatin in this patient population was four million units/m2.

Adult↗

Pentostatin therapy of T-cell lymphomas with cutaneous manifestations.

PURPOSE: To determine the side effects of and response to pentostatin in patients with T-cell lymphomas with cutaneous manifestations. PATIENTS AND METHODS: Pentostatin was administered to 28 patients who had relapsed cutaneous T-cell lymphoma or peripheral T-cell lymphoma with prominent cutaneous disease. The starting dose was between 3.75 to 5.0 mg/m(2)/d intravenous for 3 days every 3 weeks. RESULTS: Of the 24 patients assessable for response, 17 (71%) achieved a partial remission (46%) or complete remission (25%). The patients had a median number of three (range, one to 12) prior therapies. Of the 86 courses of pentostatin given, 39 were administered at doses of 5.0 mg/m(2)/d and 30 at doses of 3. 75 mg/m(2)/d. Dose escalation to 6.25 mg/m(2)/d was possible in only five courses, and toxicity necessitated dose reduction to 2.8 mg/m(2)/d in 12 courses. The most common side effects were granulocytopenia, nausea, and nonneutropenic fever. Most patients developed significant lowering of CD4 counts. Herpes zoster was seen within 1 year after pentostatin in five patients (19%). CONCLUSION: Pentostatin is an active agent in heavily pretreated T-cell lymphomas with cutaneous manifestations.

Adult↗

Pentostatin (Nipent): a review of potential toxicity and its management.

Pentostatin (Nipent; SuperGen, San Ramon, CA) is a safe and well-tolerated medication but, like all chemotherapeutic agents, it may be associated with some toxicity. The toxicity seen with pentostatin is dose and schedule dependent and can be minimized by appropriate dosing. The dose of pentostatin should never exceed 4 mg/m2. A dose reduction is required for patients with renal insufficiency. Renal and neurological toxicities may occur, yet are uncommon with appropriate dosing. Nausea and vomiting also occur; however, they are usually controlled with antiemetic therapy. Like the other purine nucleoside analogs, pentostatin is an immunosuppressive drug that may increase the risk of infection, especially with opportunistic organisms. Prophylactic antibiotics should be considered when treating patients with pentostatin.

Antibiotic Prophylaxis↗

Phase II trials of pentostatin (Nipent) in hairy cell leukemia.

Hairy cell leukemia (HCL) is a chronic lymphoproliferative disease of B-cell origin manifested by pancytopenia and splenomegaly. Before 1980 the only effective treatment for HCL was splenectomy, which resolved the cytopenia but did not eliminate the disease from the bone marrow. In addition, the majority of patients progressed after splenectomy and required further treatment. Pentostatin (Nipent; SuperGen, San Ramon, CA) is a purine antimetabolite that was found in phase I studies to induce profound lymphocytopenia Although in vitro studies suggested that T lymphocytes were most sensitive to pentostatin, patients with B-cell chronic lymphatic leukemia and low-grade non-Hodgkin's lymphoma responded to treatment in the initial phase I trials. Due to evidence that the drug was effective in lymphoproliferative disease, patients with HCL were treated with pentostatin. The promising initial results led to phase II studies in both untreated and previously treated patients. These studies demonstrated that pentostatin was highly effective as a single agent, with complete responses seen in 60% to 90% of patients. These responses were durable without maintenance chemotherapy and were seen in patients previously treated with interferon or chemotherapy. Toxicity was usually mild, with nausea and skin rashes predominating. When seen, infections resulting from neutropenia occurred early in treatment. The high response rates and low toxicity suggest that pentostatin should be considered as one of the standard treatments for HCL.

Adenosine Deaminase Inhibitors↗

Induction of intracellular and plasma 2',5'-oligoadenylate synthetase by pentostatin.

Similar to interferon alpha, pentostatin is highly effective in hairy cell leukemia and moderately active in other chronic lymphoid malignancies. In ten patients with hairy cell leukemia (HCL) and seven patients with other B-cell chronic leukemias (BCL), we have studied the intracellular 2',5'-oligoadenylate synthetase (2,5OAS) activity of the mononuclear cells before, 4 h, 24 h, and 48 h after pentostatin administration. In patients with HCL the median level of intracellular 2,5OAS increased 4.6-fold at 4 h and 11.5-fold at 24 h compared to the pretreatment value. Among the other seven patients, the median intracellular 2,5OAS remained unchanged in three patients and rose slightly by 2 to 14 times in four patients. Eleven patients (eight with HCL and two with BCL) responded to pentostatin. The median increase in 2,5OAS among the responders was 13.0-fold (range 4.8-30.0) whereas that among non-responders was 2.2-fold (range 0.2-6.3). The difference was highly significant (p less than 0.0001). In five of the total seventeen patients, the plasma levels of 2,5OAS activity were also determined and changes in plasma levels paralleled those measured intracellularly. To determine if the elevation of 2,5OAS is mediated by induction of interferon alpha, the expressions of mRNA for interferon alpha and beta were investigated by means of reverse transcription and polymerase chain reaction using the corresponding sense primers. In none of the five patients thus studied could we find an induction of mRNA for interferon alpha or beta in the leukemic cells during treatment with pentostatin. Thus, response to pentostatin correlates with induction of 2,5OAS directly and the 2',5'-oligoadenylate system seems to be involved in cytotoxicity.

2',5'-Oligoadenylate Synthetase↗

Developmental toxicity of pentostatin (2'-deoxycoformycin) in rats and rabbits.

The developmental toxicity of the potent adenosine deaminase (ADA) inhibitor, pentostatin (2'-deoxycoformycin), was investigated in pregnant rats and rabbits administered daily iv doses during organogenesis. Rats received 0, 0.01, 0.10, or 0.75 mg/kg on gestation days 6-15 and rabbits received 0, 0.005, 0.01, or 0.02 mg/kg on gestation days 6-18 and maternal and fetal parameters were evaluated on gestation day 21 (rats) or 30 (rabbits). Live fetuses were examined for external, visceral, and skeletal malformations and variations. In rats, maternal body weight gain and food consumption were significantly suppressed at doses of 0.10 and 0.75 mg/kg during the treatment period but returned to control levels during posttreatment. Increased postimplantation loss and decreased numbers of live fetuses, litter size, and fetal body weight were observed at 0.75 mg/kg. A statistically significant increase in the incidence of vertebral malformations occurred at 0.75 mg/kg. The incidence of certain skeletal variations (extra presacral vertebrae, extra ribs, hypoplastic vertebrae) was also increased at 0.75 mg/kg. Ossification of cervical centra was reduced at 0.75 mg/kg compared with controls. In rabbits, marked maternal toxicity (death, body weight loss, and decreased food consumption) and reproductive toxicity (abortion and premature delivery) occurred in all pentostatin-treated groups. However, there were no significant effects on number of live fetuses, pre- or postimplantation loss, litter size, or fetal body weights in the animals with live litters. There was also no apparent increase in the incidence of malformations or variations in the live fetuses of pentostatin-treated rabbits. Thus, these studies demonstrate developmental toxicity of pentostatin in rats and rabbits, and teratogenicity in rats, at maternally toxic doses.

Abnormalities, Drug-Induced↗

Pentostatin-augmented interstitial adenosine prevents postcardioplegia injury in damaged hearts.

This study tests the hypothesis that the adenosine deaminase inhibitor pentostatin (2-deoxycoformycin), when given before ischemia or during infusions of blood cardioplegia, augments interstitial adenosine levels and prevents postcardioplegia dysfunction in hearts with antecedent ischemia. Twenty-one anesthetized dogs were placed on cardiopulmonary bypass, and the hearts were made globally ischemic for 30 minutes. Dogs received blood cardioplegia with no pentostatin (BCP group, n = 6), pretreatment pentostatin (0.2 mg/kg) infused 5 minutes before global ischemia (PS-PTx group, n = 7), or pentostatin included only in the blood cardioplegia without pretreatment (PS-BCP group, n = 8). Microdialysate myocardial adenosine levels (an index of interstitial fluid levels) increased only modestly in the BCP group (from 0.55 +/- 0.13 microM to 2.64 +/- 0.50 microM) and the PS-BCP group (from 0.55 +/- 0.18 microM to 1.08 +/- 0.48 microM) during normothermic ischemia, but interstitial adenosine levels were not augmented further during cardioplegic arrest in either group. In contrast, the adenosine level in the PS-PTx group was significantly (p < 0.05) augmented during global ischemia (from 0.50 +/- 0.13 microM to 63.16 +/- 28.08 microM) and cardioplegia infusion (to 15.26 microM +/- 5.61 microM). Relative to baseline, postischemic left ventricular performance (end-systolic pressure-volume relation) was depressed in both the BCP (from 5.5 +/- 1.2 mm Hg/mL to 3.8 +/- 0.4 mm Hg/mL) and PS-BCP groups (from 7.1 +/- 0.9 mm Hg/mL to 3.8 +/- 0.7 mm Hg/mL). In contrast, PS-PTx restored postischemic performance (from 6.2 +/- 0.5 mm Hg/mL to 7.5 +/- 0.9 mm Hg/mL).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

Pentostatin (2'-deoxycoformycin) in the treatment of cutaneous T-cell lymphoma.

BACKGROUND: The treatment of patients with advanced or therapy-refractory cutaneous T-cell lymphoma (CTCL) remains a challenge. Pentostatin is a potent inhibitor of adenosine deaminase and is selectively toxic to lymphocytes. In a small number of patients with CTCL, it previously has been shown to be effective. OBJECTIVE: Our purpose was to evaluate the efficacy and safety of pentostatin in the treatment of patients with advanced and/or therapy-refractory CTCL. METHODS: Eighteen patients with stage I to IVb CTCL were treated with 4 to 5 mg/m2 of intravenous pentostatin every 1 to 4 weeks. RESULTS: Two patients (11%) had complete responses of 4 months and 6 years, respectively. These patients had stage III and IVa CTCL and had previously received many different external or systemic treatments. Partial remission (50% to 99% clearing) lasting for 1.5 to 6 months occurred in five patients (28%) with stage IIa (n = 3), stage IIb, and stage IVa CTCL. These patients had received a median of three prior external or systemic treatments. No major side effects were observed, and bone marrow suppression was mild. CONCLUSION: Single-agent pentostatin in intravenous doses of 4 to 5 mg/m2 is an effective systemic treatment of CTCL (39% objective response rate) with little toxicity.

Adenosine Deaminase Inhibitors↗

Pentostatin in T-cell malignancies--a phase II trial of the EORTC. Leukemia Cooperative Group.

PURPOSE: Within this phase II EORTC trial, we have investigated the safety and efficacy of pentostatin in lymphoid malignancies. We have previously reported the results in T- and B-cell prolymphocytic leukemia, B-cell chronic lymphocytic leukemia (B-CLL) and hairy cell leukemia. This report focuses on the outcome in T-cell malignancies: T-CLL, Sézary syndrome (Sézary), mycosis fungoides (MF) and T-zone lymphoma (TZL). PATIENTS AND METHODS: Of the 92 patients with these diagnoses enrolled, 76 were evaluable for response and toxicity, i.e., 25 of 28 with T-CLL, 21 of 26 with Sézary, 22 of 26 with MF, and 8 of 12 with TZL. All patients had progressive and advanced disease. Pentostatin was administered at a dosage of 4 mg/m2 every week for the first 3 weeks, then 4 mg/m2 every 14 days for another 6 weeks, followed by maintenance therapy of 4 mg/m2 monthly for a maximum of 6 months. RESULTS: Response rates (complete and partial responses) in patients with Sézary (n = 22) or MF (n = 21) were 33% and 23%, respectively, and in patients with T-CLL (n = 21) or TZL (n = 8) 8% and 25%, respectively. Sixteen (21%) patients died during the first ten weeks of treatment: twelve of progressive disease, two of infectious complications with progressive disease, one of myocard infarction and one of renal failure related to administration of i.v. contrast. Major toxicity (grade 3-4) included infection in 11% of patients, nausea/vomiting in 4%, diarrhea in 3%. Hematologic toxicity was mild to non-existent. CONCLUSIONS: We conclude that pentostatin is active in Sézary and MF but showed marginal activity in T-CLL or TZL. Toxicities are mild to moderate at the dose schedule administered. Due to its relatively specific lympholytic effect and its favorable toxicity spectrum, pentostatin might be especially useful for the palliative treatment of T-cell malignancies.

Adult↗