Successful chemotherapy with deoxycoformycin in adult T-cell lymphoma-leukaemia

Current Status of Therapeutic Approaches to Adult T-Cell Leukemia

More than 2 decades have elapsed since the proposal of adult T-cell leukemia (ATL). Since then, the discovery of the etiologic virus, human T-cell leukemia virus type I (HTLV-I), and the establishment of the diagnostic steps of serum test and molecular study have clearly defined ATL as a distinct disease entity. Because conventional chemotherapy, which is active against other lymphoid malignancies, was proven to be ineffective for treating aggressive forms of ATL, ATL has become the target of several clinical studies for the purpose of improving therapeutic outcomes. Combination chemotherapy exclusively designed for ATL has considerably elevated the treatment response rate in ATL patients, but it has not sufficiently extended the median survival time. The introduction of antiviral agents has led to surprising effects for patients with acute ATL. Monoclonal antibodies seem to be promising, especially for patients with chemotherapy-resistant disease. Unfortunately, these approaches did not prove to be sufficient for most patients with ATL to obtain long-term survival. Recent promising reports on allogeneic stem cell transplantation (allo-SCT) for ATL have suggested that allo-SCT could overcome the limitations that other treatment modalities have not surmounted. More efforts are clearly needed to clarify the usefulness of allo-SCT, especially with reduced-intensity conditioning regimens, for ATL patients.

Deoxycoformycin-containing combination chemotherapy for adult T-cell leukemia-lymphoma: Japan Clinical Oncology Group Study (JCOG9109)

Aggressive adult T-cell leukemia-lymphoma (ATL) generally has a very poor prognosis. Deoxycoformycin (DCF, pentostatin), an inhibitor of adenosine deaminase, has shown promising therapeutic efficacy for ATL. To develop a new effective therapy against aggressive ATL, we carried out a multicenter phase II study of DCF-containing combination chemotherapy. Sixty-two previously untreated patients with ATL (34, 21, and 7 patients with diseases of the acute, lymphoma, and unfavorable chronic types, respectively) were enrolled, but 2 were ineligible because they were judged to be favorable chronic types. A regimen of 1 mg/m2 vincristine intravenously on days 1 and 8, 40 mg/m2 doxorubicin intravenously on day 1, 100 mg/m2 etoposide intravenously on days 1 through 3, 40 mg/m2 prednisolone orally on days 1 and 2, and 5 mg/m2 DCF intravenously on days 8, 15, and 22 was administered every 28 days for 10 cycles unless disease progression or toxic complications occurred. Fifty-two percent of 60 eligible patients responded (95% confidence interval [CI], 38%-65%), with 17 patients (28%) achieving a complete response (CR) (95% CI, 17%-41%) and 14 achieving a partial response. The CR rate was inferior to those of both the previous Japan Clinical Oncology Group (JCOG) study (JCOG8701, 43%), a 9-drug combination chemotherapy of the second generation, and the subsequent JCOG9303 study (35%), a granulocyte colony-stimulating factor-supported, dose-intensified, 9-drug regimen. The median survival time of the 60 eligible patients in JCOG9109 was 7.4 months, and the estimated 2-year survival rate was 15.5%; these results were identical with those of JCOG8701 but inferior to those of JCOG9303. Grade 4 neutropenia and infection of grade 3 or greater were frequent (67% and 22%, respectively), and treatment-related death was observed in 4 patients (7%), septicemia in 2, and cytomegalovirus pneumonia in 2. We conclude that DCF-containing combination chemotherapy is not a promising regimen against aggressive ATL.

Global epidemic of human T-cell lymphotropic virus type-I (HTLV-I)

Infection with human T-cell lymphotrophic virus-I (HTLV-I) is now a global epidemic, affecting 10 million to 20 million people. This virus has been linked to life-threatening, incurable diseases: adult T-cell leukemia/lymphoma (ATLL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The cumulative lifetime risk of developing these incurable diseases is approximately 5% in asymptomatic patients. For the emergency physician practicing among patients from high-risk groups, HTLV-I and its associated diseases are presenting an increasing challenge. This report describes its transmission, seroprevalence, treatment, and methods of controlling spread of this retrovirus. Coinfection with HTLV-I and HIV has been shown to accelerate the progression of acquired immune deficiency syndrome (AIDS).

Purine analogs in the treatment of low-grade lymphomas and chronic lymphocytic leukemias

The purine analogs fludarabine (FAMP), 2-chlorodeoxy-adenosine (2-CDA) and 2-deoxycoformycin (DCF) comprise a novel group of agents with high activity in low-grade lymphoid malignancies. Although all three agents share several mechanisms of action, such as the induction of apoptosis, and toxic effects, such as prolonged immunosuppression, their activity appears to be different in different disorders. While FAMP and possibly also 2-CDA are highly active in chronic lymphocytic leukemia and low-grade follicular lymphomas, 2-CDA and DCF are most effective in hairy cell leukemia. However, prospective comparative evaluations are in progress and their results may ultimately help to define the appropriate indications for and potential side effects of these highly promising new agents.

Chronic lymphoid leukemias: recent advances in biology and therapy

There exists a wide variety of lymphoid leukemias derived from B and T lymphocytes. These diseases have distinct immunologic and biologic features as well as varied responses to therapeutics. The most common lymphoid leukemia is chronic lymphocytic leukemia (CLL) which is a clonal proliferation of a subset of B cells expressing the CD5 antigen. Prolymphocytic leukemia is usually derived from B cells and shares some features with CLL but is clearly a distinct entity. Hairy-cell leukemia is a B cell malignancy that is uniquely responsive to a variety of biologic and chemotherapeutic agents. Waldenström's macroglobulinemia is a B cell malignancy that secretes immunoglobulin M (IgM) and may present with the hyperviscosity syndrome. Other B cell malignancies that less commonly present as leukemias include non-Hodgkin's lymphomas such as follicular lymphoma or mantle zone lymphoma. Multiple myeloma may rarely present or evolve into a plasma cell leukemia, typically in far advanced disease. T cell malignancies that may present as chronic lymphoid leukemias, and in the past have often been referred to as T cell chronic lymphocytic leukemia, are large granular lymphocytic leukemia, adult T cell leukemia/lymphoma, Sézary cell leukemia and rare cases of non-Hodgkin's lymphoma that are T cell derived and may present or evolve into a leukemic phase. There is also a rare T cell counterpart of prolymphocytic leukemia. Distinguishing these diseases is critical for optimal care of these patients.

Advances in therapy for hairy cell leukemia. A review

BACKGROUND

Hairy cell leukemia (HCL) is a chronic B-cell malignancy, typically seen in middle-aged men, characterized by pancytopenia, splenomegaly, immunologic abnormalities, and morphologically typical neoplastic mononuclear cells in the blood, bone marrow, liver, spleen, and other tissues. Diagnosis is confirmed by demonstration of hairy cells in biopsy specimens from the bone marrow or spleen or in peripheral blood. The natural history of this lymphoproliferative disorder varies. Patients may die early during the initial phase of therapy; others may require no therapy; and for some, splenectomy alone, without further treatment, may suffice for many years. Recently, the nucleosides pentostatin (2'-deoxycoformycin) (DCF) and 2'-chlorodeoxyadenosine (2-CdA) have been shown to produce greater numbers of durable complete remissions with curative potential in patients with HCL. The treatment options, with emphasis on major therapeutic advances with alpha-interferon, DCF, and 2-CdA, are reviewed in this article.

METHODS

Studies on HCL published from 1958 to 1992 were reviewed using the Cancerline and Medline retrieval systems and other bibliographies.

RESULTS

Management of HCL has changed in the last decade as a result of three new effective agents: alpha-interferon DCF, and 2-CdA. DCF has produced an overall response rate of 86% and a complete remission rate of 62%. 2-CdA has yielded an overall response rate of 95% and a complete remission rate of 82%. Alpha-interferon has given an overall response rate of 82% and a complete remission rate of 8%. Other agents with limited activities include chlorambucil, cyclophosphamide, cytarabine, vincristine, doxorubicin, and zorubicin hydrochloride. The effects of lithium carbonate, immunotherapy, splenic irradiation, androgens, and leukaphoresis are minimal and transient.

CONCLUSIONS

Modern management of HCL with 2-CdA and DCF is now potentially curative rather than palliative in some patients; however, the optimal therapeutic approach remains uncertain. Alpha-interferon has been approved by the Food and Drug Administration as the first-line drug therapy, followed by DCF in non-responding patients. 2-CdA remains an experimental therapy, but its higher response rate and ease of administration may make it the first-line treatment of choice. Additional research into the biology of HCL and further clinical trials are needed to determine the optimal treatment strategy for this disorder. Therefore, the best therapeutic approach at the current time is to include patients with HCL in ongoing clinical trials.

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.

Deoxyadenosine triphosphate acting as an energy-transferring molecule in adenosine deaminase inhibited human erythrocytes

Deoxyadenosine triphosphate (dATP) is present in adenosine deaminase (ADA)-deficient or ADA-inhibited human red cells and in the red cells of the opossum Didelphis virginiana. In order to investigate the functions of dATP in the red cell, red cells were treated with 2'-deoxycoformycin (dCf), a powerful inhibitor of ADA, and incubated with phosphate, deoxyadenosine and glucose. These red cells in which ATP was almost completely replaced by dATP, had the same shape, lactate production, nucleotide consumption, stability of reduced glutathione, osmotic fragility and cell deformability as red cells containing ATP. Cells merely depleted of ATP showed reduced viability. This indicates that dATP compensates well for the absence of ATP and acts as an energy-transferring molecule to maintain cell viability. These results indicate that the accumulation of dATP or the reduction of ATP is not the cause of the hemolysis observed after dCf administration.

Chemotherapy of chronic haematological malignancies

After years of stagnation in the treatment of chronic haematological malignancies, some interesting agents have emerged which might improve the prognosis of these diseases. For chronic leukaemias of lymphoid lineage, three new chemical agents, all purine analogues, seem to be of particular interest. Pentostatin is a specific inhibitor of ADA and has been shown to be highly efficient in producing CR in patients with HCL. Its relative merit compared with IFN-alpha for the treatment of HCL is being studied in ongoing randomized trials. Pentostatin is also active in B-CLL and promising activities have been demonstrated in T- or B-PLL and ATCL. Fludarabine is an analogue of adenine which is resistant to the deamination of ADA. It has been reported to be highly active for patients with both pretreated or non-treated B-CLL. CR rates of 13% with overall response rates of 57% can be achieved, even in heavily pretreated patients. Its activity in the other lymphoid malignancies is not yet known. CdA, a substrate analogue of ADA, has also produced encouraging results in B-CLL, HCL and T cell malignancies, and in some patients with just one single course. Thus far, experience with this drug comes from one institution and requires further confirmation. For chronic myeloproliferative diseases, little progress has yet been made. Although IFN-alpha seems to be active in CML and to result in cytogenetic remissions in bone marrow, a definite advantage of this biological agent over conventional chemotherapy as regards survival and life quality has not yet been proven. Allogeneic bone marrow transplantation is beneficial for those patients who are eligible. No remarkable advances have been made in the treatment of myeloproliferative disorders except for the development of an antiplatelet drug, anagrelide. This agent seems to be highly effective in controlling thrombocytosis. The relative merit of this agent as compared with IFN-alpha, as well as the impact of this agent on the survival and on life-quality of patients with myeloproliferative disorders, have yet to be defined.

Purine metabolism in feline lymphomas

Deficiency of the purine metabolic enzyme adenosine deaminase causes severe immunodeficiency. Retroviruses have been reported to decrease the activity of adenosine deaminase, and many retroviruses, including feline leukemia virus, cause immunodeficiency. Levels of purine metabolic enzymes including adenosine deaminase and consequences of adenosine deaminase inhibition were investigated in feline leukemia virus-infected fresh tumor cells and infected and uninfected cell lines. No evidence of virus effect on levels of adenosine deaminase or other purine metabolic enzymes was detected. Neoplastic cells demonstrated considerable heterogeneity of activity levels of purine metabolic enzymes.

2' Deoxycoformycin (pentostatin) for refractory non-Hodgkin's lymphoma: a CALGB phase II study

Seventy-six eligible patients with relapsed or refractory non-Hodgkin's lymphoma (NHL) were treated with 2'-deoxycoformycin (pentostatin) at a dose of 4 mg/m2 intravenously weekly for three weeks and then every other week for a minimum of five total treatments. All patients had measurable disease, near normal hematologic, renal, and hepatic function, and a performance status of 0 or 1. Severe hematologic toxicity was observed in 13% of patients; severe renal or neurologic toxicity was observed in less than 5% of patients. There were no treatment-related deaths. Objective therapeutic responses were seen in 16% of patients (five complete response [CR] and seven partial response [PR]). However, in three of the patients achieving CR and one patient achieving PR, dexamethasone was employed as an anti-emetic, making the response of these patients to pentostatin difficult to evaluate. There were eight responses (3 CR) in patients with diffuse histologies and four responses (2 CR) in patients with nodular or mixed histologies. Three responses were in patients with a T-cell phenotype. Three of five patients with diffuse well-differentiated lymphoma (IWF A) responded. We conclude that 2' deoxycoformycin is only minimally active at this dose and schedule against refractory or relapsed NHL. The possibility that low grade B- and T-cell malignancies are more sensitive to 2' deoxycoformycin deserves further investigation.

Potentiation of growth-inhibitory activity of 9-beta-D-arabinofuranosyladenine by 2'-deoxycoformycin in human cultured cell lines derived from leukemias and lymphomas

Growth-inhibitory activity of 2'-deoxycoformycin (DCF) and 9-beta-D-arabinofuranosyladenine (Ara-A) used either singly or in combination was assessed in 30 human cultured cell lines (seven T-cell, nine B-cell, five non-T,non-B and nine myeloid cell lines) derived from leukemias and lymphomas. DCF had little activity even at 100 microM on any of the cell lines, while Ara-A had an obvious inhibitory effect on them, especially on non-T,non-B cell lines at 10 microM or less. Lymphoid cell lines were apparently more sensitive to the combined use of Ara-A and DCF than myeloid cell lines. DCF potentiated the antiproliferative activity of Ara-A not only in T-cell lines with high adenosine deaminase (ADA) activity, but also in some other cell lines with low ADA activity. DCF was stable in the culture medium, but Ara-A in the medium containing cultured cells was rapidly inactivated. DCF completely inhibited the inactivation of Ara-A in the medium containing P12/ICH or NALM-6, but not in the medium containing Daudi. This suggests that there is some unknown mechanism(s) of inactivation of Ara-A other than ADA in Daudi, which was insensitive to Ara-A in the presence of 1 microM DCF. The capacity of DCF to inhibit degradation of Ara-A in the medium containing these cultured cells correlated with the level of Ara-A sensitivity potentiated by DCF. In all seven T-cell lines, seven of the nine B-cell lines, all five non-T,non-B cell lines, and only three of nine myeloid cell lines, the IC50 value for Ara-A decreased to 5 microM or less in the presence of 1 microM DCF. These results suggest that the combination of DCF and Ara-A may be effective against various types of lymphoid malignancies and some myeloid leukemias.

Adult T-cell leukemia

Adult T-cell leukemia (ATL) is a leukemia caused by a monoclonal expansion of HTLV-I-infected T-cells expressing a CD4 antigen. The clinical features of ATL include lymphadenopathy, hepatosplenomegaly, frequent skin lesions, hypercalcemia and a rapidly fatal course. The cell surface phenotype, cytogenetics and functions of leukemic cells are described in association with various clinical manifestations and HTLV-I infection. Leukemic cells constitutively express the p55 (Tac antigen) subunit of the interleukin-2 (IL-2) receptor. Its association with the function of HTLV-I gene products and its possible role in the leukemogenesis of ATL are discussed. Finally, the potential of some therapeutic agents which may selectively eliminate the Tac-expressing leukemic cells in vitro are described, and these may provide an improvement over currently ineffective combination chemotherapy.

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.

Manifestations of human T-lymphotropic virus type I infection

HTLV-I, the first human oncovirus, is a type C retrovirus linked to the development of ATLL. The virus shows a striking ethnogeographic distribution that is only partially understood. Certain populations at high risk for AIDS appear to have a higher incidence of HTLV-I infection. The extended latent period renders present knowledge of the sequelae and natural history of HTLV-I seropositivity incomplete, although recent data suggest that HTLV-I infection may have important implications for blood transfusion, organ transfer, and public health policy. A variety of clinical syndromes have been associated with infection, ranging from an asymptomatic carrier state to acute ATLL with lymphadenopathy, hepatosplenomegaly, hypercalcemia, cutaneous lesions, and systemic immunosuppression. Conventional chemotherapy is marginally effective; innovative approaches to therapy are presently being evaluated.

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.

Spontaneous remission and relapse in adult T cell lymphoma/leukaemia associated with HTLV-I

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Successful remission induction with deoxycoformycin in elderly patients with T-helper prolymphocytic leukaemia

Two elderly patients with prolymphocytic leukaemia (PLL) of T helper phenotype were treated with the adenosine deaminase inhibitor--deoxycoformycin--and achieved remission. The first patient has remained in an unmaintained remission for over a year. The second patient, treated with a regime which produced less side effects, subsequently relapsed in skin and lymph nodes and died. In view of the rarity of this condition a multi-centre assessment of the effectiveness of deoxycoformycin is indicated. T-lymphocyte colony formation in both cases was found to be reduced. Co-culture of the patients' lymphocytes with nonadherent mononuclear cells from normal individuals also showed inhibition of T-colony formation indicating that lack of nutrients or accessory cells was not responsible for low T-colony forming capacity.

Clinical consequences of 2'-deoxycoformycin treatment in patients with refractory adult T-cell leukaemia

Five patients from the Kyushu area in Japan with adult T-cell leukaemia (ATL) refractory to conventional chemotherapeutic agents were treated with 5 mg/m2 of the adenosine deaminase inhibitor, 2'-deoxycoformycin (DCF), intravenously (i.v.) for 3 consecutive days, followed by 5 mg/m2 i.v. weekly. Two patients showed a good response, and three were resistant to DCF. One patient with ATL receiving DCF had a continuous remission without further therapy. Another patient in the terminal stage received three daily injections of 7.5 mg of DCF. The most prominent change was the drop in the leucocyte count. The cell count fell from 116.4 X 10(9)/l to 2.0 X 10(9)/l on day 7. The only adverse effects of DCF therapy were gastrointestinal toxicity, nausea and vomiting. These results suggest that DCF may be a valuable drug for treating refractory ATL.