Alpha-interferon therapy for essential thrombocythaemia

SURPASS-ET: phase III study of ropeginterferon alfa-2b versus anagrelide as second-line therapy in essential thrombocythemia

Patients diagnosed with high-risk essential thrombocythemia (ET) have limited treatment options to reduce the risk of thrombosis and lessen the progression of the disease by targeting the molecular source. Hydroxyurea is the recommended treatment, but many patients experience resistance or intolerance. Anagrelide is an approved second-line option for ET, but concerns of a higher frequency of disease transformation may affect its role as a suitable long-term option. Interferons have been evaluated in myeloproliferative neoplasms for over 30 years, but early formulations had safety and tolerability issues. SURPASS-ET (NCT04285086) is a phase III, open-label, multicenter, global, randomized, active-controlled trial that will evaluate the safety, efficacy, tolerability and pharmacokinetics of ropeginterferon alfa-2b compared with anagrelide as second-line therapy in high-risk ET.

Immunotherapy and Immunomodulation in Myeloproliferative Neoplasms

Myeloproliferative neoplasms are characterized by chronic inflammation. The discovery of constitutively active JAK-STAT signaling associated with driver mutations has led to clinical and translational breakthroughs. Insights into the other pathways and novel factors of potential importance are being actively investigated. Various classes of agents with immunomodulating or immunosuppressive properties have been used with varying degrees of success in treating myeloproliferative neoplasms. Early clinical trials are investigating the feasibility, effectiveness, and safety of immune checkpoint inhibitors, cell-based immunotherapies, and SMAC mimetics. The dynamic landscape of immunotherapy and immunomodulation in myeloproliferative neoplasms is the topic of the present review.

Essential thrombocythaemia treated with recombinant interferon: 'real world' United Kingdom referral centre experience

Standard first-line therapy choice for essential thrombocythaemia (ET) requiring cytoreduction, supported by randomized trials, is low-dose aspirin with hydroxycarbamide, but the role of recombinant interferon-alfa (IFNα)-2a/2b and pegylated (PEG)-IFN-α-2a/2b is increasingly highlighted. Longer-term outcome data, however, remains somewhat scarce, particularly in the 'real world'. We hereby report on a large, well-annotated cohort of ET patients from a single referral centre undergoing therapy with either IFNα or (PEG)-IFN-α-2a/2b and demonstrate high rates of complete haematological responses, good tolerability and safety, low rates of thromboembolic events in compliant patients and confirm feasibility of long-term therapy in a significant proportion of patients.

Interferon alpha-2b for Essential Thrombocythaemia: Results in 13 Previously Untreated Patients

Interferon alpha-2b (αIF) was administered to 13 previously untreated patients with essential thrombocythaemia (ET). Pretreatment median platelet count was 1.178 (range, 662 to 1,700) x 10(9)/L, with ten patients showing values above 1,000 × 10(9)/L. Six patients had vascular symptoms attributable to ET, whereas in the remaining cases treatment was instituted due to either an increased vascular risk or platelet counts higher than 1,000 × 10(9)/L. With an induction regimen of αIF 3 MU/day, given subcutaneously, a rapid decrease in the platelet counts was observed in all cases. Two patients did not complete the induction therapy because of unacceptable toxic side-effects at the time their platelet counts approached normal values. In the remaining 11 patients a complete haematologic response (platelets below 400 × 10(9)/L) was observed, after a median of 9.5 (range, 2.6 to 36) weeks from the start of therapy. In only 3 patients was dose escalation of interferon to 5 MU/day required. Eleven patients experienced flu-like symptoms, that could be well controlled by oral paracetamol in 7 cases. After discontinuing therapy a rise in the platelet counts was observed in all patients, after a median of 5 (range, 2 to 35) weeks. Two patients subsequently refused to continue on interferon therapy, whereas in the remainder a dose of 3 MU 2 to 4 times weekly maintained normal platelet counts.

Biological rationale and clinical use of interferon in the classical BCR-ABL-negative myeloproliferative neoplasms

Because of its antiapoptotic, antiproliferative, and immunomodulatory properties, interferon (IFN) has been broadly used as an antiviral and antineoplastic agent. These properties are particularly suitable for the treatment of the classical BCR-ABL-negative myeloproliferative neoplasms (MPN), including essential thrombocytosis (ET), polycythemia vera (PV), and myelofibrosis (MF). In the MPN, IFN has been shown to suppress megakaryopoiesis, inhibit erythroid colony-forming cells, suppress bone marrow fibroblast progenitors, induce cytogenetic remission, and reduce the JAK2 V617F allele burden, sometimes completely. Although efficacy has long been demonstrated in the MPN, toxicities were frequent with recombinant IFN, tempering enthusiasm. However, with pegylated-IFN, because of less toxicity, there has been renewed interest, and recent studies in the MPN have shown hematologic and molecular response or remission in ET and PV; a smaller study in early MF has shown IFN's potential to retard fibrosis. The role of IFN in the treatment of MPN is being re-evaluated on the basis of these studies, and will be better defined as results return from an ongoing international study.

Interferon-alpha targets JAK2V617F-positive hematopoietic progenitor cells and acts through the p38 MAPK pathway

OBJECTIVE

Interferon-alpha (IFNalpha) therapy leads to hematological remissions and a reduction of the JAK2V617F allele burden in patients with polycythemia vera (PV). In this study, the cellular target by which IFNalpha affects hematopoiesis in PV patients was evaluated.

MATERIALS AND METHODS

CD34(+) cells were isolated from normal bone marrow and the peripheral blood of patients with PV and were treated in vitro with each of the three commercially available forms of IFNalpha: IFNalpha 2b, pegylated IFNalpha 2a (Peg-IFNalpha 2a), and pegylated IFNalpha 2b (Peg-IFNalpha 2b).

RESULTS

Each form of IFNalpha was equally potent in suppressing hematopoietic colony formation by normal CD34(+) cells, but Peg-IFNalpha 2a and IFNalpha 2b were more effective than Peg-IFNalpha 2b in inhibiting burst-forming unit erythroid-derived colony formation by PV CD34(+) cells. In addition, exposure of PV CD34(+) cells to equal doses of Peg-IFNalpha 2a and IFNalpha 2b resulted in a 38% to 40% reduction in the proportion of JAK2V617F-positive hematopoietic progenitor cells (HPC), while equivalent doses of Peg-IFNalpha 2b did not reduce the number of malignant HPC. Further studies explored the mechanism by which IFNalpha induced PV HPC growth inhibition. Treatment of Peg-IFNalpha 2a increased the rate of apoptosis of PV CD34(+) cells and the phosphorylation/activation of p38 mitogen-activated protein kinase in PV CD34(+) cells, while the p38-specific inhibitor SB203580 reversed the growth inhibition and apoptosis induced by Peg-IFNalpha 2a.

CONCLUSION

These data suggest that low doses of IFNalpha selectively and directly suppress PV JAK2V617F HPC and that these agents act through the p38 mitogen-activated protein kinase pathway.

Therapy of essential thrombocythemia with alpha-interferon: results and prospects

Conventional treatment of symptomatic essential thrombocythemia (ET) consists of long-term administration of myelosuppressive cytotoxic agents which, although efficacious in most cases, are associated with leukemogenic potential. Alpha-interferon (IFN) exerts a dose-dependent inhibitory influence on thrombopoiesis through a direct antiproliferative effect on megakaryocytic precursors. Therefore, it may provide a biologic, potentially non-mutagenic alternative to conventional cytotoxic treatments. At daily doses ranging from 1 to 5 M.U., alpha-IFN is efficacious in inducing a hematologic response in most patients with ET. Response to IFN is a gradual process. The median time to hematologic response varies from 1 to 3 months and a significant proportion of patients reach and maintain normal platelet counts with low doses (1-3 M.U./d). Normalization of marrow megakaryocytosis requires longer treatment (9-12 months). Also patients resistant to cytotoxic drugs may respond to alpha-IFN, suggesting a lack of cross-resistance between the two treatment modalities. Side-effects, although not severe, represents a limit to the administration of adequate doses of IFN in about 25% of cases. Once hematologic response has been obtained, both low-dose IFN and cytotoxic drugs are effective as maintenance. The full potentialities of alpha-IFN in ET in combination with cytotoxic drugs or with other cytokines need to be further investigated.

Interferon-alpha therapy in bcr-abl-negative myeloproliferative neoplasms

Interferon (IFN) was the first cytokine discovered 50 years ago, with a wide range of biological properties, including immunomodulatory, proapoptotic and antiangiogenic activities, that rapidly raised interest in its therapeutic use in malignancies. IFN-receptor characterization was also pivotal in the discovery of the JAK/STAT signaling pathway. Among the large IFN family, mainly one of the type I IFN, IFN-alpha2, is used in therapy. Many clinical trials have shown remarkable efficacy of IFN-alpha in bcr-abl-negative myeloproliferative neoplasms (MPNs), especially polycythemia vera (PV), and essential thrombocythemia (ET). IFN-alpha induces about 80% of hematological responses in those diseases and is able to reduce splenomegaly, as well as relieve pruritus and other constitutional symptoms. Yet its use was limited by toxicity, leading to early treatment discontinuation in about 20% of the patients. However, its lack of leukemogenic potential and its possible use during pregnancy have already made IFN-alpha the drug of choice for younger MPN patients. In addition, several studies have shown a probably selective effect of IFN-alpha on PV and ET clones, as shown by cytogenetic remissions, reversions to polyclonal hematopoiesis, and more recently by induction of JAK2V617F complete molecular remissions in PV which may widen the indications of IFN-alpha in JAK2-mutated MPN.

Interferon α therapy for patients with essential thrombocythemia

BACKGROUND

In 1986, a Phase II trial of recombinant interferon-alpha (IFN-alpha) was initiated as therapy for patients with essential thrombocythemia (ET).

METHODS

Patients were treated with subcutaneous IFN-alpha at a dose of 5 x 10(6) units/m(2) daily. In responding patients, the therapy lasted at least 3 years.

RESULTS

Twenty-three patients (14 females and 9 males; median age, 41 years; age range, 20-63 years) with a median platelet count of 1350 x 10(9)/L were treated. After a median follow-up of 174 months (14.5 years), 15 of 20 evaluable patients (75%) responded, including 14 patients who achieved a complete hematologic response (CHR) (6 of them with bone marrow remission) and 1 patient who demonstrated a partial response. The median time to response was 6 months (range, 0.5-36 months), and the median response duration was 48 months (range, 5-114 months). Seven patients who achieved a CHR and were taken off therapy after they completed 3 years of maintenance therapy sustained their response for a median of 28 months. No symptoms or signs of thrombosis or hemorrhage were observed in responding patients. Eleven of 14 patients (78%) who achieved a CHR developed a recurrence, and 2 of 5 patients with recurrences who were rechallenged with IFN-alpha achieved a second response. The treatment was tolerated relatively well.

CONCLUSIONS

IFN-alpha was safe and effective therapy for patients with ET, and the ability of IFN-alpha to reverse disease pathology and possibly modify the clinical course of patients with ET warrants its investigation in larger, prospective trials.

Phase II study of alpha2 interferon in the treatment of the chronic myeloproliferative disorders (E5487): a trial of the Eastern Cooperative Oncology Group

BACKGROUND

In vitro and clinical data suggest a therapeutic role for alpha2 interferon (IFN) in the treatment of the chronic myeloproliferative disorders. Accordingly, a multiinstitutional, Phase II trial of IFN in patients with agnogenic myeloid metaplasia (AMM), essential thrombocythemia (ET), and polycythemia rubra vera (PRV) in the spent phase was initiated. The objectives of this study were 1) to investigate the response rates that may be achieved with IFN in the treatment of patients with these disorders, 2) to estimate the durability of the responses, and 3) to assess the toxicities of IFN in these populations.

METHODS

Enrollment was limited to patients with AMM, ET, or PRV who already had developed 1) anemia or transfusion dependency, 2) thrombocytosis uncontrolled by standard therapy, 3) hemostatic complications, or 4) symptomatic splenomegaly. Initially, patients were started on IFN at a dose of 5 MU/m(2) per day as a subcutaneous injection. After the first 16 patients had been treated, the starting dose of IFN was reduced to 2 MU/m(2) per day because of unexpected toxicities.

RESULTS

IFN demonstrated different levels of efficacy and toxicity in each of the three diseases studied. The overall response rates achieved among the evaluable patients in each category were as follows: ET, 88.2% (n = 17 patients; 1 complete response and 14 partial responses); PRV, 41.7% (n = 12 patients; 1 complete response and 4 partial responses); and AMM, 3.2% (n = 31 patients; 0 complete responses and 1 partial response). Thrombocytosis and leukocytosis were controlled in nearly all patients, with reversal of splenomegaly and resorption of myelofibrosis achieved in fewer patients. The toxicities attributed to IFN differed notably among the three disease groups: patients who had AMM suffered systemic and neurologic toxicities more frequently than patients who had PRV or ET; whereas patients who had ET experienced a greater than expected incidence of hepatic abnormalities, most typically transient elevations of serum amino acid transaminase levels.

CONCLUSIONS

The current study demonstrated the safety and efficacy of IFN in patients with ET, PRV, and AMM. Objective responses and/or disease stabilization were obtained in patients with all three disease entities, including the reversal of splenomegaly and resorption of myelofibrosis in some patients.

Sticky platelet syndrome and thrombocythemia

Platelets are intimately involved in the pathogenesis of thromboembolic disorders, especially arterial forms of thrombosis. Although most arterial thromboses develop on the basis of endothelial injuries, some do not. In these instances "hyperactive" platelets could be the cause. Hyperaggregable platelets have been described in association with a number of acquired disease entities whereby the cause-and-effect relationship is unclear. In contrast, the sticky platelet syndrome is a congenital, autosomal dominant disorder, characterized by hyperaggregable platelets in response to ADP, epinephrine, or both. Patients usually seek treatment for transient or permanent arterial vascular occlusions. These are often precipitated by stressful events. Treatment with low-dose aspirin (81 mg/day) reverses clinical symptoms and hyperaggregability in the laboratory.

Essential thrombocythemia (ET): moving from palliation to cure

Essential thrombocythemia (ET) is a clonal hematopoietic stem cell myeloproliferative disorder characterized by megakaryocytic hyperplasia and persistent thrombocytosis. The clinical presentation and evolution of ET are heterogeneous. This review highlights the current treatment options in the management of ET, including hydroxyurea, anagrelide and both regular and pegylated interferons. Anagrelide, while very effective at controlling counts and symptoms in most patients, may not consistently reduce the bone marrow megakaryocyte mass. Interferon is very effective and not associated with leukemogenesis, but has not been proven to restore polyclonal hematopoiesis and has significant dose-related adverse events. Pegylated interferon represents a significant improvement over the unmodified interferon preparations. Novel therapeutic options directed towards eradication of the malignant ET clone are required.

Alpha-interferon therapy induces improvement of platelet counts in children with chronic idiopathic thrombocytopenic purpura

PURPOSE

To investigate alpha-interferon (IFN) therapy for children with chronic idiopathic thrombocytopenic purpura (ITP).

PATIENTS AND METHODS

Patients with refractory ITP lasting more than 12 months from diagnosis were included if they had platelet counts <50 x 10(9)/L and had received no treatment during the past month. Patients received IFN (3 x 10(6) U/m2 per dose), three times per week for 4 weeks; if partial (<150 x 10(9)/L) or no response was obtained, the same dose was continued for another 8 weeks. In patients with favorable response and subsequent decrease to pre-treatment values, an additional 4 weeks of treatment could be administered.

RESULTS

Fourteen patients (ages 4-20 y) receiving 17 IFN courses were included. Mean initial platelet count was 29 +/- 15 x 10(9)/L. A significant increase was achieved during 14 of 17 courses (82.4%). All but two responses were transitory, and platelets returned to initial values after IFN discontinuation (mean 44 +/- 26 days). Considering the best response achieved by each patient, we observed: 1) 10 patients who achieved a sustained improvement of platelet count throughout the treatment period, decreasing to initial values after therapy was stopped; 2) one patient who achieved platelet count >150 x 10(9)/L, remaining with normal platelets at 18 months; 3) one patient who achieved platelet count >150 x 10(9)/L, remaining with platelets between 100 and 140 x 10(9)/L at 48 months; 4) one patient who had no response; and 5) one patient in whom therapy worsened the thrombocytopenia. A mild to moderate flu-like syndrome and a moderate decrease of the absolute neutrophil count were the only side effects observed.

CONCLUSION

Interferon therapy induces a significant increase of platelet count and seems to be a valid alternative therapy to attempt the achievement of prolonged remission in refractory ITP, to defer splenectomy in younger children, or to improve platelet count before planned splenectomy.

Hypothalamic-pituitary axis remains intact after interferon-alpha treatment in hematologic diseases

Many endocrinologic disturbances have been reported during and after interferon-alpha (IFN-alpha) treatment. These disturbances have often been caused by autoantibodies. The aim of this prospective study was to evaluate whether IFN-alpha causes hormonal changes and if it is necessary to search for such disturbances routinely. Ten patients with hematologic malignancies were examined before and after 4 months of IFN-alpha treatment. Pituitary function was tested by hypothalamic releasing hormones (thyrotropin-releasing hormone, TRH, growth hormone-releasing hormone, GHRH, gonadotropin-releasing hormone, GnRH). The adrenal glands were tested with the adrenocorticotropin (ACTH) test. The human chorionic gonadotropin (hCG) test was performed on the men (n = 4). The IFN treatment was well tolerated, and no long-term hormonal side effects were found. The testosterone/sex hormone binding globulin (SHBG) index tended to improve. There were no significant differences between the hormone responses before and after IFN-alpha treatment. We conclude that the hypothalamic-pituitary axis remains intact after IFN-alpha treatment. There is no need to follow patients endocrinologically if the patients are not predisposed by autoantibodies.

Interferon-alpha in childhood haematological malignancies

The application of cytostatics has brought about a breakthrough in the treatment of childhood haematological malignancies in the past 20 years. Chemotherapy appears to be least successful in the rare, low and very high mitotic index diseases, which often have an enormous tumour-burden. The suitability of chemotherapy in minimal residual leukaemia is also of some doubt. In these situations a 'conservative' treatment may be more appropriate. Because interferon-alpha has a distinct mechanism of action, and a broad-spectrum haematopoietic inhibitory activity, it is relatively nontoxic and noncancerogenic, and it may have a role in the treatment of malignant haematological disorders, either as a mono- or combination therapy. The exact indications and dosages for interferon in childhood malignancies are far from clear. Up to now, it has proved to be most efficacious in small tumour masses, providing a theoretical basis for application in minimal residual disease. Controlled clinical data, however, are not yet available. It remains to be determined whether or not interferon can be added to current chemotherapy protocols without a significant reduction of dose. Hopefully, a deeper understanding of the activities of interferon will allow us to plan better trials with combination treatments.

Interferon-alpha and its effects on the cytokine cascade: a pro- and anti-inflammatory cytokine

Interferon-alpha (IFN alpha) has emerged as an important regulator of growth and differentiation, affecting cellular communication and signal transduction pathways as well as immunological control. The efficacy of IFN alpha has been demonstrated in many different diseases of viral, malignant, angiogenic, allergic, inflammatory, and fibrotic origin. Cytokines are pleiotropic and redundant molecules showing a wide variety of biologic functions on various tissues and cells, and several different cytokines exert similar and overlapping functions on certain cells. Data gained in the last years support this view also for IFN alpha. Initially thought to have mainly immunomodulating and proinflammatory effects, recent data suggest that IFN alpha has several anti-inflammatory properties. These newly identified anti-inflammatory and immunosuppressive functions may help to explain some of the IFN mechanisms.

Interferon treatment in polycythaemia vera

Recent studies have shown rIFN alpha to be an effective agent in the management of polycythemia vera. Red cell mass can be controlled within 6 to 12 months, eliminating the need for phlebotomy in up to 70% of cases. In addition, significant improvement in the platelet counts, iron status, pruritus scores and the degree of splenomegaly have been reported. Most patients require between 9 and 25 x 10(6)U/week, although once the disease is under control it may be possible to reduce both the dose and frequency of administration. Side-effects remain a significant problem, occurring in over 30% of patients, and may be related to the high mean age of the patients. Long-term studies are now indicated to determine if the natural history of the disease is altered and whether, in particular, the incidence of myelofibrosis and/or leukaemic transformation is reduced.

Interferon-alpha in the treatment of essential thrombocythemia

Interferon alpha (IFN) inhibits the growth of megakaryocytic progenitors in normal hematopoiesis and in patients with essential thrombocythemia (ET) leading to a reduction of peripheral platelet counts. The effectiveness in the induction therapy of patients with ET is demonstrated in 11 international studies including 212 patients. With an average dose of about 3 mill IU IFN daily, the response rate was about 90%. Further studies investigated the practicability and the success of IFN maintenance therapy. The results show that IFN can effectively control platelet counts over a period of several years. During maintenance the IFN dose could be reduced in the majority of patients. However, sustained unmaintained complete remissions were obtained in only 12% of the patients. Side effects were frequently the limiting factors in treatment with IFN especially in older patients. Analyzing a total of 273 patients, IFN therapy was terminated in 25% against the primary treatment plan. Of the currently effective drugs in controlling the platelet counts in ET, IFN is the only antiproliferative agent with immuno-modulating properties. Thus far, no leukemogenic or significant gonadotoxic effects have been observed. In a subset of the patients off all therapy, the sustained remissions support a long-term tumor load reduction effect by IFN. Thus, IFN is a promising agent in cytoreductive treatment of ET especially in younger patients.

Effects of interferon-alpha therapy on immune parameters in immune thrombocytopenic purpura

Interferon-alpha (IFN alpha) has been shown to increase platelet numbers in patients with immune thrombocytopenic purpura (ITP), but the basis for this effect is not known. In this study changes in immune function were monitored following administration of IFN alpha to seven patients whose ITP had proved refractory to conventional therapy. Patients' peripheral blood mononuclear cells were cultured with phytohaemagglutinin and culture supernatants assayed for cytokine production. Production of the Th1 cytokines IL-2 and IFN-gamma was low in patients compared to healthy controls, and amounts of these tended to increase after IFN alpha therapy. In two patients high levels of IL-10 were detectable in culture, and these were reduced after IFN alpha. In patients who had high serum concentrations of IL-4 or IL-10, these were also decreased following therapy. Natural killer cell activity, which was low in the patients prior to therapy, was increased following administration of IFN alpha. In those patients with detectable platelet-associated autoantibody to gpIIb/IIIa, the amounts were reduced after treatment. Two patients had an unusually high percentage of T cells expressing the gamma delta T cell receptor, which decreased after therapy. The findings are consistent with an increase in Th 1 activity and a decrease in autoantibody production following IFN alpha therapy, which may be related to the beneficial effects of this cytokine.

Treatment of essential thrombocythemia with anagrelide

Essential thrombocythemia (ET) is a myeloproliferative disorder characterized by persistent elevation in platelet count. It is a rare disorder in children, and children who have symptoms require treatment. We report the successful use of anagrelide, with few toxic effects, in the treatment of three children with ET.

Primary thrombocythemia: a current perspective

The relationships among thrombocytosis, abnormal platelet aggregation and altered hemostasis in primary thrombocythemia remain poorly understood. Consequently, the appropriate management of asymptomatic patients is controversial and needs to be individualized. For symptomatic patients, conventional therapy, usually hydroxyurea, is directed primarily at lowering the platelet count by suppression of megakaryocyte activity. Recombinant interferon alpha can selectively lower platelet counts and may offer a reasonable alternative. Recent experience with anagrelide is also most promising in both symptomatic and asymptomatic patients. Current thoughts on the pathogenesis and management guidelines are presented here.

Essential thrombocythemia: a retrospective analysis of 39 cases

Thirty-nine Chinese patients presenting as essential thrombocythemia (ET) were analyzed retrospectively. The median age at presentation was 69 years and the M:F ratio was 1.35:1. At diagnosis, 33 cases (84%) were asymptomatic and the diagnosis was made incidentally, while 3 cases (8%) presented with small vessel, and 2 cases (5%) with large vessel, thrombosis. One patient (3%) presented with minor bleeding. The platelet count ranged from 0.9-34 x 10(12)/l. Of 12 karyotypes done, 2 cases were abnormal, both showing the Philadelphia (Ph) chromosome. First-line therapy was radiophosphorus (32P) in 3 cases, melphalan in 20 cases, and hydroxyurea in 12 cases; 4 cases did not receive specific therapy. During the follow-up (mean = 4 years), no thrombotic or bleeding episodes were observed. One patient with the Ph chromosome underwent blastic transformation. These results indicate that bleeding and thrombosis occur significantly less in Chinese patients than in Western patients. The Ph chromosome appears to be a bad prognostic indicator. Because of the very low incidence of complications and good prognosis, the authors believe that cytoreductive therapy is best achieved by the use of hydroxyurea instead of alkylating agents or radiophorphours, as the latter agents are potentially leukemogenic.

Alpha-2a interferon therapy and antibody formation in patients with essential thrombocythemia and polycythemia vera with thrombocytosis

In ten patients with essential thrombocythemia and polycythemia vera with thrombocytosis we have investigated the therapeutic effect of recombinant alpha-2a interferon (Roceron-A) given subcutaneously in a maintenance dosage of 3 million units three times weekly. The aim was to normalize the platelet count (< or = 400 x 10(9)/L). One of the secondary aims was to study platelet activity measured as beta-thromboglobulin (beta-TG) in urine. All but one patient could administer the injections and in all patients a significant reduction in platelet values was seen. The treatment was discontinued in three patients due to side effects of interferon, two because of hair loss (one with irreversible alopecia), and one because of depression. Three patients developed antibodies to alpha-2a interferon and a concomitant rise in the platelet level; in one patient therapy was switched to leukocyte alpha-interferon with an excellent response. The initial levels of beta-TG were elevated in 9/10 patients and were significantly reduced at 6 months in 4/5 patients not developing antibodies. Six patients are still on alpha-interferon therapy with a long-term follow-up of 3-3.5 years. We conclude that alpha-interferon therapy may be an alternative in patients with thrombocytosis and/or complications necessitating treatment.

Recombinant alpha-2B interferon treatment for childhood T--lymphoblastic disease in relapse. A Pediatric Oncology Group Phase II study

BACKGROUND

Children with chemotherapy refractory T-cell lymphoblastic leukemia/lymphoma were given alpha-interferon (alpha-IFN) to evaluate the efficacy and toxicity of this biologic response modifier.

METHODS

Twenty children with T-cell acute lymphoblastic leukemia (T-cell ALL) in marrow relapse and one patient with mediastinal recurrence of T-cell non-Hodgkin's lymphoma (T-cell NHL) were enrolled. All patients had failed at least two previous multiagent drug trials. Recombinant alpha-IFN was given at 30 million U/M2/dose intravenously or subcutaneously for 10 doses over 14 days, followed by 3 doses per week until disease progression occurred.

RESULTS

One child had a complete response (< 5% blasts) and three patients a partial response (5-25% blasts) in their bone marrow. All patients eventually showed signs of progressive disease. Significant toxicities included cardiac hypofunction in two patients and profound lethargy in two patients.

CONCLUSIONS

alpha-IFN is tolerated in children with T-cell ALL and T-cell NHL and has activity against chemotherapy resistant disease.

Recombinant interferon alpha-2b in the treatment of polycythemia vera

We studied the effects of recombinant alpha 2-b interferon (alpha 2-b IFN) in a dose of 3 x 10(6)U intramuscularly three times a week for 1 year in 13 patients affected by polycythemia vera (PV) previously treated with phlebotomy only. Response to treatment was evaluated by reduction of the number of phlebotomies required to retain normal hematocrit value. Ten out of 13 patients (77%) responded to treatment; in 4 of them the exigency of phlebotomy was completely eliminated. In all responders a concomitant decrease of platelet count and splenomegaly was obtained. Treatment was well tolerated and side effects were easily controlled. We conclude that alpha-IFN may represent an attractive therapeutic option in the management of the proliferative stages of PV.

alpha-Interferon therapy for severe chronic idiopathic thrombocytopenic purpura in children

We report the use of alpha 2b-interferon in 15 children with symptomatic, chronic idiopathic thrombocytopenic purpura, who did not respond to standard therapy. The platelet count increased in nine children during therapy. In six children the increase lasted less than 6 weeks. An increased platelet count was seen when a higher dose was used in two of four initial nonresponders. One responder who relapsed had an identical response when retreated with the same dose. No significant side effects were documented. Further studies are required to establish the optimal dose and administration schedule of alpha 2b-interferon for use in children with chronic idiopathic thrombocytopenic purpura.

Morphometric study of the bone marrow in polycythemia vera following interferon-alpha therapy

Bone marrow cellularity and extent of fibrotic change were determined in nineteen patients with polycythemia vera, treated with interferon-alpha (IFN) for 1 year. The cellularity was evaluated with an interactive semiautomatic method using Leitz TAS plus microscope: in particular, number and size of megakaryocytes were evaluated after immunostaining with Y2/51 (CD 61); reticulin content was studied by light microscope with a semiquantitative method. Before IFN therapy mean cellularity was 80.5% (+/- 13.7). After 6 and 12 months mean cellularity was 75.4% and 68.4% respectively. Six months after cessation of IFN therapy the cellularity was 69.1%. A decrease of the number, density and morphometrical parameters of megakaryocytes was also remarked. Reticulin fibrosis was mild in 13 cases and moderate in 6 cases before IFN therapy. Reticulin content was unmodified during therapy in all cases but two, in which fibrosis changed from mild to moderate. In conclusion IFN therapy is to be considered a good method in polycythemia vera for the control of proliferative activity of bone marrow but with IFN therapy one cannot determine regression of marrow fibrosis.

Increase in platelet count following short course therapy with recombinant alpha-2b-interferon in immune thrombocytopenic purpura in childhood

Two boys, aged three and seven years with immune thrombocytopenic purpura continued to show platelet counts below 20,000/mm3 inspite of treatment with high dose gammaglobulin and steroids. Alpha-2b-interferon injections were followed by normalisation of platelet counts in both patients. No side effects were seen. Alpha-interferon may be a safe and effective treatment for childhood-ITP.

A long-term clinical trial of interferon alpha-therapy in essential thrombocythemia

In a prospective clinical trial involving six patients suffering from essential thrombocythemia (ET), recombinant human interferon alpha 2b significantly and consistently lowered highly elevated peripheral platelet numbers over long time periods. One patient has now been on continuous treatment for 4 years. During the treatment phase none of the patients suffered from bleeding episodes, thrombosis or disturbances of the microcirculation. The interferon maintenance dose varies considerably from patient to patient, but it is usually much lower than the induction dose. One of the patients had to be withdrawn from the study due to interferon-specific chronic toxicity concomitant with the development of non-neutralizing interferon antibodies. With the exception of one patient, stopping interferon treatment led to an increase in peripheral platelet numbers of up to one million cells per microliter of blood within 4 to 12 weeks. We conclude that interferon alpha can correct peripheral thrombocytosis in selected patients with essential thrombocythemia over a period of years and prevent morbidity attributable to this disease.

Recombinant alpha 2B interferon in combination with oral chemotherapy in late chronic phase chronic myeloid leukaemia

The place of alpha interferon (IFN) therapy in the treatment of chronic myeloid leukaemia (CML) is under intensive investigation at present. It is now established that as a single agent it can provide good disease control in the chronic phase and that cytogenetic responses will occur in a minority of patients. However its impact on long term survival has been less certain. Optimal haematological and cytogenetic results have to date been seen when IFN is used in the early phase of the disease, i.e. within one year of diagnosis. We have performed a prospective single arm study on the effect on survival of the addition of low dose IFN (9 mU/week) to conventional oral chemotherapy in patients who were at a median of 19 months from the initial diagnosis at the time of study entry. Comparison of this cohort with a control group of CML patients treated with oral chemotherapy only at the same participating institutions gave an estimated 72% reduction in the risk of death as a result of IFN therapy. Median survival for the IFN group has not been reached at 43 months compared with a median survival of 33 months for the chemotherapy alone group. These results suggest that the introduction of low dose IFN at any stage in the chronic phase may produce a worthwhile improvement in survival.

Remission may continue after termination of rIFN alpha-2b treatment for essential thrombocythemia

Essential thrombocythemia, a myeloproliferative disorder of clonal origin, is often associated with various clinical manifestations resulting from thromboembolic or hemorrhagic complications. The long-established successful method of treatment with cytotoxic agents or radioactive phosphorus has recently been superseded by interferon alpha. We treated 14 symptomatic patients with 5 x 10(6) IU recombinant interferon alpha-2b s.c. daily. 12/14 pts responded within 14-75 days. When platelet counts decreased to below 450 g/l the frequency of administration was reduced stepwise. 7 patients remained in CR during this reduction phase and treatment was stopped in 5 pts after 12-32 months. Until now, 3 of them are still in continuous good PR without any drug therapy and free of symptoms for 3+, 19+ and 36+ months. Continuous response during maintenance was associated with age, initial platelet count and time required to reduce platelet counts to less than 450 g/l.

alpha Interferon treatment of essential thrombocythaemia and other myeloproliferative disorders with excessive thrombocytosis

The effect of recombinant interferon alfa-2b on platelet count, thrombocytosis-associated symptoms and marrow fibrosis was studied in 18 patients with myeloproliferative diseases and associated thrombocytosis (nine with essential thrombocythaemia, three with polycythaemia vera, three with myelofibrosis and three with chronic myelogenous leukaemia). A reduction of the platelet count below 600 x 10(9)/L was achieved in 94%, and below 400 x 10(9)/L in 77% of the patients within 8 to 330 days of treatment. The selective thrombocytosis-reducing effect of alpha interferon was maintained for long periods of time in most patients without serious side effects. Thrombocytosis-associated symptoms were relieved once the number of platelets was reduced to near normal levels. Marrow reticulin content was found to be reduced after treatment in two of the seven patients studied. Side effects of alpha interferon were flu-like symptoms, which usually subsided within 7 days of treatment.

alpha Interferon in the management of essential thrombocythaemia

Thirteen patients (mean age 60.7 years; female:male ratio 10:3) with essential thrombocythaemia were treated with 3 million units (MU)/day interferon alfa-2b subcutaneously (s.c.) for 12 weeks, with all patients requiring a dose reduction after 4 weeks. The mean pretreatment platelet count was 1,400 x 10(9)/L and megakaryocytes were increased in all cases. Splenomegaly was present in six patients and haemorrhagic phenomena were observed in two. Nine patients (69.2%) had objective responses, including two (15.4%) complete responses (platelets less than 450 x 10(9)/L) which were then maintained with 5 MU interferon twice a week. Acute toxicity consisted of flu-like symptoms in 12 patients. Chronic toxicity (mainly leucopenia) was observed in nine patients. In conclusion, initial therapy and then requiring maintenance therapy at a reduced dose. However, the frequent side effects observed make it advisable to use a low dose of interferon alfa-2b, and to treat only those patients with significant symptoms and signs of thrombocytosis.

Maintenance therapy in the myeloproliferative disorders: the current options

Recombinant interferon alfa-2a has been shown to be an effective induction agent in essential thrombocythaemia and thrombocythaemia associated with other myeloproliferative disorders, including chronic granulocytic leukaemia, polycythaemia rubra vera and myelofibrosis. Few data exist on the use of the recombinant interferons as maintenance agents in patients with thrombocythaemia. A cohort of 22 previously untreated patients, with essential thrombocythaemia, were treated with recombinant interferon alfa-2a maintenance therapy for a minimum period of 6 months. Effective long-term control of platelet counts, without evidence of haematological toxicity, was achieved in 19/22 patients. No objective haemorrhagic or thrombotic event occurred in 298 patient-months of interferon therapy. Three patients discontinued interferon alpha therapy due to adverse side-effects. Interferon alfa-2a is an effective maintenance agent in essential thrombocythaemia and is discussed in this context.