Efficacy trial of pipobroman in polycythemia vera and incidence of acute leukemia

The Platin-X series: activation, targeting, and delivery

Anticancer platinum (Pt) complexes have long been considered to be one of the biggest success stories in the history of medicinal inorganic chemistry. Yet there remains the hunt for the "magic bullet" which can satisfy the requirements of an effective chemotherapeutic drug formulation. Pt(iv) complexes are kinetically more inert than the Pt(ii) congeners and offer the opportunity to append additional functional groups/ligands for prodrug activation, tumor targeting, or drug delivery. The ultimate aim of functionalization is to enhance the tumor selective action and attenuate systemic toxicity of the drugs. Moreover, an increase in cellular accumulation to surmount the resistance of the tumor against the drugs is also of paramount importance in drug development and discovery. In this review, we will address the attempts made in our lab to develop Pt(iv) prodrugs that can be activated and delivered using targeted nanotechnology-based delivery platforms.

Second line therapies in polycythemia vera: What is the optimal strategy after hydroxyurea failure?

Cytoreductive therapies have traditionally been the standard treatment for older patients with polycythemia vera (PV) or those with a history of prior thrombosis. Hydroxyurea (HU) is the most frequently used cytoreductive agent in PV. However, approximately 24% of patients treated with HU will eventually develop resistance or intolerance and patients who fail HU have an increased risk of death, transformation to myelofibrosis or acute myeloid leukemia. Interferon-alpha has been used in younger PV patients and is capable of inducing a complete hematologic response and significant reductions, or even eradication, of JAK2 V617F mutation allele burdens in a small but notable subset of PV patients. The potential toxicities of interferon-alpha must be weighed against the disease control benefit in a case-by-case fashion. Recently JAK2 inhibitor, ruxolitinib, demonstrated significant improvement in controlling the hematocrit and splenomegaly versus best available therapy in patients with PV who failed or are intolerant to HU and currently is FDA-approved in this setting. In this review, we will discuss novel emerging therapies for PV with a special focus on the currently available and upcoming treatment options for patients who fail HU.

Where to Turn for Second-Line Cytoreduction After Hydroxyurea in Polycythemia Vera?

The goals of therapy in patients with polycythemia vera (PV) are to improve disease-related symptoms, prevent the incidence or recurrence of thrombosis, and possibly delay or prevent the transformation into myelofibrosis or acute myeloid leukemia (AML). Cytoreductive therapies have been used in older patients and those with a history of thrombosis to achieve these goals. Hydroxyurea (HU) remains the first-line cytoreductive choice; however, up to one in four patients treated with HU over time will develop resistance or intolerance to HU. More importantly, patients who fail HU have a 5.6-fold increase in mortality and a 6.8-fold increase risk of transformation to myelofibrosis or AML; therefore, alternative therapies are needed for these patients. Interferon-α has been used in PV and has shown significant activity in achieving hematologic responses and decreasing JAK2 V617F mutation allele burden. JAK inhibition has also been investigated and recently garnered regulatory approval for this indication. In this review, we will discuss the current treatment options that are available for patients after HU and the novel therapies that are currently under investigation.

IMPLICATIONS FOR PRACTICE

The outcomes of PV patients who fail or who are intolerant of hydroxyurea are poor. Although pegylated interferon can be considered in younger patients, currently, ruxolitinib is the only U.S. Food and Drug Administration-approved agent in this setting, representing a viable option, leading to hematocrit control and a reduction in spleen size and constitutional symptoms. Although a small number of patients will achieve a molecular response with continuous treatment, the implications of such response on the clinical outcomes are still unknown. Patients whose disease is not adequately controlled with ruxolitinib, or who lose their response, can be treated with low-dose busulfan or pipobroman; however, they should be encouraged to participate in trials with novel therapies.

Unique Use of Alkylation for Chemo-Redox Activity by a Pt(IV) Prodrug

Resistance towards chemotherapeutics displayed by cancer cells is a significant stumbling block against fruitful cisplatin-based therapy. A unique dual-acting chemotherapeutic modality, Platin-B, a prodrug of cisplatin and pipobroman-mimicking alkylating agent, was constructed to circumvent tumor resistance. Platin-B exhibited a superior cytotoxicity profile in cisplatin-resistant cancer cells. Enhanced activity and the ability to overcome cancer-induced resistance of Platin-B was related to adduct formation with intracellular glutathione, followed by the activity of Platin-B on the mitochondria of cells, along with its conventional nuclear activity. Alkylating moieties present on Platin-B enhanced its cellular and subcellular concentration and protected it from early drug sequestration by biological thiols.

Leukemic transformation in myeloproliferative neoplasms: therapy-related or unrelated?

Polycythemia vera, essential thrombocythemia, and primary myleofibrosis are chronic myeloproliferative neoplasms (MPNs) associated with an increased morbidity and mortality. MPNs are also associated with progression to acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS). The "true" rate of transformation is not known mainly due to selection bias in clinical trials and underreporting in population-based studies. The outcome after transformation is dismal. The underlying mechanisms of transformation are incompletely understood and in part remain an area of controversy. There is an intrinsic propensity in MPNs to progress to AML/MDS, the magnitude of which is not fully known, supporting a role for nontreatment-related factors. High doses of alkylating agents, P(32) and combined cytoreductive treatments undoubtedly increase the risk of transformation. The potential leukemogenic role of hydroxyurea has been a matter of debate due to difficulties in performing large prospective randomized trials addressing this issue. The main focus of this review is to elucidate therapy-related leukemic transformation in MPNs with a special focus on the role of hydroxyurea.

Treatment of polycythemia vera with hydroxyurea and pipobroman: final results of a randomized trial initiated in 1980

PURPOSE

The overall impact of hydroxyurea (HU) or pipobroman treatments on the long-term outcome of patients with polycythemia vera (PV) has not been assessed in randomized studies. We report final analyses from the French Polycythemia Study Group (FPSG) study, which randomly assigned HU versus pipobroman as first-line therapy in 285 patients younger than age 65 years.

PATIENTS AND METHODS

The full methodology has been described previously. FPSG results were updated with a median follow-up of 16.3 years. Statistical analysis was performed by using competing risks on the intention-to-treat population and according to main treatment received.

RESULTS

Median survival was 17 years for the whole cohort, 20.3 years for the HU arm, and 15.4 years for the pipobroman arm (P = .008) and differed significantly from that in the general population. At 10, 15, and 20 years, cumulative incidence of acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) was 6.6%, 16.5%, and 24% in the HU arm and 13%, 34%, and 52% in the pipobroman arm (P = .004). Cumulative myelofibrosis incidence at 10, 15, and 20 years according to main treatment received was 15%, 24%, and 32% with HU versus 5%, 10%, and 21% with pipobroman (P = .02).

CONCLUSION

Data from this unique randomized trial comparing HU with another cytoreductive drug in PV showed that (1) survival of patients with PV treated with conventional agents differed from survival in the general population, (2) evolution to AML/MDS is the first cause of death, (3) pipobroman is leukemogenic and is unsuitable for first-line therapy, and (4) incidence of evolution to AML/MDS with HU is higher than previously reported, although consideration should be given to the natural evolution of PV.

A review of the therapeutic agents used in the management of polycythaemia vera

The acquired clonal disorder Polycythaemia Vera leads to increased erythropoiesis, myelopoiesis and megakaryopoeisis. These anomalies result in an increased incidence of thromboembolic events, transformation to acute leukaemia and myelofibrosis. Treatments which aim to reduce the event rate may increase anaemia but may also affect the rate of complications. This paper reviews the evidence for the treatments which have been used in the management of the disorders over a 50 plus year period. Assessment of this evidence and its limitations form the basis for the current suggested management plans.

Risk of leukemic transformation in PV and ET patients

Despite a prolonged survival of around 15 years linked to a prolonged complete remission induced by myelosuppression, myeloproliferative syndromes such as polycythemia vera (PV) and essential thrombosis (ET) remain at risk of lethal adverse affects such as thrombotic events and acute transformation. The major risk at diagnosis, in the absence of treatment, is essentially thrombosis. Different therapeutic trials have shown the necessity to maintain circulating blood cells (RBC and platelets counts) near normal levels to avoid thrombosis. Phlebotomies alone in PV lead in the long run to metaplasia and increased platelet counts and should only be kept for emergency cell count reduction. Myelosuppression is thus until recently the most widely accepted effective alternative. However, the effects of long term chronic administration of myelosuppresive agents needs to be analyzed and monitored as the biological changes which appear during the course of these diseases linked or not to the intrinsic clonal haematopoietic abnormality may lead to malignant transformation. Thus, alternative therapies need to be evaluated and predisposition factors taken in account.

Treatment of polycythemia vera and essential thrombocythemia: the role of pipobroman

Pipobroman (PB) is a neutral amide of piperazine with a chemical structure close to that of alkylating agents, although the exact mechanism of action of PB has not been demonstrated. PB has well documented clinical activity in polycythemia vera (PV) and essential thrombocythemia (ET). Recent long-term follow-up studies on PV and ET patients receiving PB have facilitated the definition of the risk of late transformation into myelofibrosis with myeloid metaplasia (MMM) or acute leukemia (AL). This report gives an overview of the treatment with PB in patients with PV and ET focusing on clinical activity, administration dose and schedule, toxicity, impact on short- and long-term complications. From our experience and from the data reported in the literature the high clinical activity of PB in both PVand ET becomes evident. This drug allows, within 3 months, to attain a response in more than 90% of patients, without clinically relevant toxicities. The 10-years risk of thrombosis of patients treated with PB is about 15%, similar to that registered with hydroxyurea, the most widely used agent in PVand ET. The antiproliferative activity of PB on bone marrow megakaryocytes seems of particular value in lowering the occurrence of post-PV and post-ET MMM, whose risk (< 4% at 10 years) is the lowest registered with available treatments. The 10-year risk of acute leukemia with PB is 5% in PVand 3% in ET, which is only slightly higher than that expected as a natural evolution of the disease. In conclusion, the use of PB is a definite alternative to hydroxyurea in patients with PV and ET at high risk of thrombosis.

Polycythemia vera

The differential diagnosis of an elevated hematocrit and the criteria for the diagnosis of polycythemia vera present little or no problem; however, there is not a consensus on therapy. Spivak likened this to a conundrum--"an intricate and difficult problem." Nonetheless, it can be argued that on the basis of the following criteria--life expectancy, the absence of toxicity, and long remissions an average of 3.1 years or a median of 2 years--and with acute leukemia no more common than in other regimens except phlebotomy alone (a regimen that cannot be sustained), 32P should be the treatment of choice except in pregnant women. Others, but not all, share this view. This is in contrast to the statement, "Thus chemotherapy treatment of [polycythemia vera] patients is not as easy, innocuous, and well tolerated as it is generally believed". Patients treated with phlebotomy alone were subjected to an unacceptably high incidence of early thrombotic events. Unavailability of pipobroman eliminates this choice.

Polycythemia vera: a comprehensive review and clinical recommendations

More than a century has elapsed since the appearance of the modern descriptions of polycythemia vera (PV). During this time, much has been learned regarding disease pathogenesis and PV-associated molecular aberrations. New information has allowed amendments to traditional diagnostic criteria. Phlebotomy remains the cornerstone treatment of PV, whereas myelosuppressive agents may augment the benefit of using phlebotomy for thrombosis prevention in high-risk patients. Excessive aspirin use is contraindicated in PV, although the use of lower-dose aspirin has been shown to be safe and effective in alleviating microvascular symptoms including erythromelalgia and headaches. Recent studies have shown the utility of selective serotonin receptor antagonists for treating PV-associated pruritus. Nevertheless, many questions remain unanswered. What is the specific genetic mutation or altered molecular pathway that is causally related to the disease? In the absence of a specific molecular marker, how is a working diagnosis of PV made? What evidence supports current practice in the management of PV? This article summarizes both old and new information on PV; proposes a modern diagnostic algorithm to formulate a working diagnosis; and provides recommendations for patient management, relying whenever possible on an evidence-based approach.

Modern treatment strategies in polycythemia vera

Polycythemia vera (PV), one of the chronic myeloproliferative disorders (MPD), is characterized by predominant erythroid proliferation and secondary platelet proliferation, and by progression from a proliferative stage to a metastatic phase and finally a malignant phase. These characteristics expose patients to increased risk for thrombohemorrhagic complications, myeloid metaplasia, myelofibrosis, and acute leukemic conversion irrespective of treatments. Currently, there are three agents-hydroxyurea (HU), interferon-alfa (IFN-alpha), and anagrelide-that differ in mechanisms of action and in treating specific phenotypic manifestations of PV, suggesting a potential role for combination therapy. They also differ widely in side effects profiles and severity. Because of the differing risks for long-term complications associated with these agents, age is an important variable in selecting treatments. Patients at high risk for thrombohemorrhagic complications all require cytoreduction, as do patients at intermediate risk who are not effectively managed by phlebotomy and low-dose aspirin. In younger patients, the safest and most effective combination treatment appears to be anagrelide plus IFN-alpha, while in older patients anagrelide plus hydroxyurea may be effective. HU is used sparingly in younger patients because of the long-term increased risk of mutagenicity and possibly leukemogenesis. IFN-alpha is particularly indicated for patients with myeloid metaplasia evidenced by splenomegaly. Anagrelide, which acts on the mature megakaryocyte to prevent platelet budding, is uniquely efficacious in the control of platelet counts.

Chronic myeloproliferative disorders

The Philadelphia chromosome-negative chronic myeloproliferative disorders (CMPD), polycythemia vera (PV), essential thrombocythemia (ET) and chronic idiopathic myelofibrosis (IMF), have overlapping clinical features but exhibit different natural histories and different therapeutic requirements. Phenotypic mimicry amongst these disorders and between them and nonclonal hematopoietic disorders, lack of clonal diagnostic markers, lack of understanding of their molecular basis and paucity of controlled, prospective therapeutic trials have made the diagnosis and management of PV, ET and IMF difficult. In Section I, Dr. Jerry Spivak introduces current clinical controversies involving the CMPD, in particular the diagnostic challenges. Two new molecular assays may prove useful in the diagnosis and classification of CMPD. In 2000, the overexpression in PV granulocytes of the mRNA for the neutrophil antigen NBI/CD177, a member of the uPAR/Ly6/CD59 family of plasma membrane proteins, was documented. Overexpression of PRV-1 mRNA appeared to be specific for PV since it was not observed in secondary erythrocytosis. At this time, it appears that overexpression of granulocyte PRV-1 in the presence of an elevated red cell mass supports a diagnosis of PV; absence of PRV-1 expression, however, should not be grounds for excluding PV as a diagnostic possibility. Impaired expression of Mpl, the receptor for thrombopoietin, in platelets and megakaryocytes has been first described in PV, but it has also been observed in some patients with ET and IMF. The biologic basis appears to be either alternative splicing of Mpl mRNA or a single nucleotide polymorphism, both of which involve Mpl exon 2 and both of which lead to impaired posttranslational glycosylation and a dominant negative effect on normal Mpl expression. To date, no Mpl DNA structural abnormality or mutation has been identified in PV, ET or IMF. In Section II, Dr. Tiziano Barbui reviews the best clinical evidence for treatment strategy design in PV and ET. Current recommendations for cytoreductive therapy in PV are still largely similar to those at the end of the PVSG era. Phlebotomy to reduce the red cell mass and keep it at a safe level (hematocrit < 45%) remains the cornerstone of treatment. Venesection is an effective and safe therapy and previous concerns about potential side effects, including severe iron deficiency and an increased tendency to thrombosis or myelofibrosis, were erroneous. Many patients require no other therapy for many years. For others, however, poor compliance to phlebotomy or progressive myeloproliferation, as indicated by increasing splenomegaly or very high leukocyte or platelet counts, may call for the introduction of cytoreductive drugs. In ET, the therapeutic trade-off between reducing thrombotic events and increasing the risk of leukemia with the use of cytoreductive drugs should be approached by patient risk stratification. Thrombotic deaths seem very rare in low-risk ET subjects and there are no data indicating that fatalities can be prevented by starting cytoreductive drugs early. Therefore, withholding chemotherapy might be justifiable in young, asymptomatic ET patients with a platelet count below 1500000/mm(3) and with no additional risk factors for thrombosis. If cardiovascular risk factors together with ET are identified (smoking, obesity, hypertension, hyperlipidemia) it is wise to consider platelet-lowering agents on an individual basis. In Section III, Dr. Gianni Tognoni discusses the role of aspirin therapy in PV based on the recently completed European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP) Study, a multi-country, multicenter project aimed at describing the natural history of PV as well as the efficacy of low-dose aspirin. Aspirin treatment lowered the risk of cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke (relative risk 0.41 [95% CI 0.15-1.15], P =.0912). Total and cardiovascular mortality were also reduced by 46% and 59%, respectively. Major bleedings were slightly increased nonsignificnsignificantly by aspirin (relative risk 1.62, 95% CI 0.27-9.71). In Section IV, Dr. Giovanni Barosi reviews our current understanding of the pathophysiology of IMF and, in particular, the contributions of anomalous megakaryocyte proliferation, neoangiogenesis and abnormal CD34(+) stem cell trafficking to disease pathogenesis. The role of newer therapies, such as low-conditioning stem cell transplantation and thalidomide, is discussed in the context of a general treatment strategy for IMF. The results of a Phase II trial of low-dose thalidomide as a single agent in 63 patients with myelofibrosis with meloid metaplasia (MMM) using a dose-escalation design and an overall low dose of the drug (The European Collaboration on MMM) will be presented. Considering only patients who completed 4 weeks of treatment, 31% had a response: this was mostly due to a beneficial effect of thalidomide on patients with transfusion dependent anemia, 39% of whom abolished transfusions, patients with moderate to severe thrombocytopenia, 28% of whom increased their platelet count by more than 50 x 10(9)/L, and patients with the largest splenomegalies, 42% of whom reduced spleen size of more than 2 cm.

Acute myeloid leukemia (AML) having evolved from essential thrombocythemia (ET): distinctive chromosome abnormalities in patients treated with pipobroman or hydroxyurea

ET is a chronic myeloproliferative disorder rarely evolving into AML, sometimes preceded by a myelodysplastic syndrome (MDS). Such transformations mostly occur in patients treated with radiophosphorous ((32)P) or alkylating agents, especially busulfan. Recently, concern has also arisen about the long-term safety of hydroxyurea (HU). Pipobroman (PI), a well tolerated and simple to use drug, constitutes a valid alternative to those cytoreductive treatments. The present study reports on 155 ET patients treated at our institution from 1985 to 1995, and monitored until December 2000. A good control of thrombocytosis was achieved with PI as the only treatment in 106 patients and with HU in 23 patients. Twenty-six patients received no treatment. After a median follow-up of 104 months, seven patients (four treated with HU, and three with PI) developed AML whereas one patient treated with PI developed MDS. A significant difference in progression-free survival was observed between HU- and PI-treated patients (P = 0.004). A short-arm deletion of chromosome 17 was most frequently detected in HU-treated patients, while a long-arm trisomy of chromosome 1 and a monosomy 7q were seen in PI-treated patients. No TP53 mutation was discovered in the six patients studied (two HU-treated and four PI-treated). We conclude that these cytogenetic abnormalities are not linked to the natural history of the disease, but rather that they might be induced by the cytoreductive treatment.

Aplastic anemia responsive to cyclosporine complicating the evolution of polycythemia vera

We report here a very unusual patient with Polycythemia vera treated with Pipobroman who developed severe aplastic anemia following administration of the drug. Six months later, because of lack of response, cyclosporine therapy was given there was rapid and complete hematological recovery, highly suggestive of an immune-mediated mechanism, in this case.

Acute Myeloid Leukemia and Myelodysplastic Syndromes Following Essential Thrombocythemia Treated With Hydroxyurea: High Proportion of Cases With 17p Deletion

Treatment with alkylating agents or radiophosphorous (32P) has been shown to carry a certain leukemogenic risk in myeloproliferative disorders (MPDs), including essential thrombocytemia (ET). The leukemogenic risk associated to treatment with hydroxyurea in ET, on the other hand, is generally considered to be relatively low. Between 1970 and 1991, we diagnosed ET in 357 patients, who were monitored until 1996. One or several therapeutic agents had been admistered to 326 patients, including hydroxyurea (HU) in 251 (as only treatment in 201), pipobroman in 43, busulfan in 41, and32P in 40. With a median follow-up duration of 98 months, 17 patients (4.5%) had progressed to acute myeloid leukemia (AML; six cases) or myelodysplastic syndrome (MDS; 11 cases). Fourteen of these patients had received HU, as sole treatment in seven cases, and preceded or followed by other treatment in seven cases, mainly pipobroman (five cases). The remaining three leukemic progressions occurred in patients treated with 32P (two cases) and busulfan (one case). The incidence of AML and MDS after treatment, using 32P alone and 32P with other agents, busulfan alone and with other agents, HU alone and with others agents, and pipobroman alone and with other agents was 7% and 9%, 3% and 17%, 3.5% and 14%, and 0% and 16%, respectively. Thirteen of 17 patients who progressed to AML or MDS had successful cytogenetic analysis. Seven of them had rearrangements of chromosome 17 (unbalanced translocation, partial or complete deletion, isochromosome 17q) that resulted in 17p deletion. They also had a typical form of dysgranulopoiesis combining pseudo Pelger Hüet hypolobulation and vacuoles in neutrophils, and p53 mutation, as previously described in AML and MDS with 17p deletion. Those seven patients had all received HU, as the only therapeutic agent in three, and followed by pipobroman in three. The three patients who had received no HU and progressed to AML or MDS had no 17p deletion. A review of the literature found cytogenetic analysis in 35 cases of AML and MDS occurring after ET, 11 of whom had been treated with HU alone. Five of 35 patients had rearrangements that resulted in 17p deletion. Four of them had been treated with HU alone. These results show that treatment with HU alone is associated with a leukemic risk of approximately 3.5%. A high proportion of AML and MDS occurring in ET treated with HU (alone or possibly followed by pipobroman) have morphologic, cytogenetic, and molecular characteristics of the 17p− syndrome. These findings suggest that widespread and prolonged use of HU in ET may have to be reconsidered in some situations, such as asymptomatic ET.

Acute Myeloid Leukemia and Myelodysplastic Syndromes Following Essential Thrombocythemia Treated With Hydroxyurea: High Proportion of Cases With 17p Deletion

Treatment with alkylating agents or radiophosphorous (32P) has been shown to carry a certain leukemogenic risk in myeloproliferative disorders (MPDs), including essential thrombocytemia (ET). The leukemogenic risk associated to treatment with hydroxyurea in ET, on the other hand, is generally considered to be relatively low. Between 1970 and 1991, we diagnosed ET in 357 patients, who were monitored until 1996. One or several therapeutic agents had been admistered to 326 patients, including hydroxyurea (HU) in 251 (as only treatment in 201), pipobroman in 43, busulfan in 41, and32P in 40. With a median follow-up duration of 98 months, 17 patients (4.5%) had progressed to acute myeloid leukemia (AML; six cases) or myelodysplastic syndrome (MDS; 11 cases). Fourteen of these patients had received HU, as sole treatment in seven cases, and preceded or followed by other treatment in seven cases, mainly pipobroman (five cases). The remaining three leukemic progressions occurred in patients treated with 32P (two cases) and busulfan (one case). The incidence of AML and MDS after treatment, using 32P alone and 32P with other agents, busulfan alone and with other agents, HU alone and with others agents, and pipobroman alone and with other agents was 7% and 9%, 3% and 17%, 3.5% and 14%, and 0% and 16%, respectively. Thirteen of 17 patients who progressed to AML or MDS had successful cytogenetic analysis. Seven of them had rearrangements of chromosome 17 (unbalanced translocation, partial or complete deletion, isochromosome 17q) that resulted in 17p deletion. They also had a typical form of dysgranulopoiesis combining pseudo Pelger Hüet hypolobulation and vacuoles in neutrophils, and p53 mutation, as previously described in AML and MDS with 17p deletion. Those seven patients had all received HU, as the only therapeutic agent in three, and followed by pipobroman in three. The three patients who had received no HU and progressed to AML or MDS had no 17p deletion. A review of the literature found cytogenetic analysis in 35 cases of AML and MDS occurring after ET, 11 of whom had been treated with HU alone. Five of 35 patients had rearrangements that resulted in 17p deletion. Four of them had been treated with HU alone. These results show that treatment with HU alone is associated with a leukemic risk of approximately 3.5%. A high proportion of AML and MDS occurring in ET treated with HU (alone or possibly followed by pipobroman) have morphologic, cytogenetic, and molecular characteristics of the 17p− syndrome. These findings suggest that widespread and prolonged use of HU in ET may have to be reconsidered in some situations, such as asymptomatic ET.

Treatment of Polycythemia Vera: The Use of Hydroxyurea and Pipobroman in 292 Patients Under the Age of 65 Years

Nonradiomimetic drugs, hydroxyurea (HU) and pipobroman (Pi), were administred to relatively young subjects with polycythemia vera (PV) in an attempt to decrease the leukemogenic risk observed in patients treated with 32P. Clinical safety, hematological efficacy, risk of carcinoma or leukemia, and frequency of progression to myelofibrosis have not yet been defined in long-term studies, and no comparative studies of HU and Pi have been conducted. Since 1980, 292 patients with PV diagnosed before the age of 65 years were randomized to receive treatment with HU (25 mg/kg/d, followed by low-dose maintenance) or Pi (1.2 mg/kg/d, followed by low-dose maintenance). Patients were followed until death or until May 1997. Drug tolerance was often poor; leg ulcers and buccal aphthous ulcers (with HU) and gastric pain and diarrhea (with Pi) sometimes required treatment change, mainly in the HU arm. Hematological stability, especially in terms of platelet count, was very often insufficient with HU (45% of cases), but the risk of thrombo-embolic event was similar in both arms. Actuarial survival was similar in the two arms and shorter than that of the reference population. The risk of leukemia was approximately 10% at the 13th year, with no significant difference between the two arms. The risk of carcinoma (when excluding the skin cancers) was similar in both groups. There was a high risk of progression to myelofibrosis in the patients treated by HU, which was significantly higher than with Pi.

Risk of leukaemia, carcinoma, and myelofibrosis in 32P- or chemotherapy-treated patients with polycythaemia vera: a prospective analysis of 682 cases. The "French Cooperative Group for the Study of Polycythaemias"

An analysis of the risk of progression towards leukemia, carcinoma and myelofibrosis was performed in 93 patients treated by 32P alone (PVSG protocols) since 1970-1979, 395 patients over the age of 65 years treated by 32P with or without maintenance therapy using hydroxyurea (French protocol) since 1980-1994, and 202 patients under the age of 65 treated by either hydroxyurea or pipobroman since 1980. The risk of leukemia, or myelodysplasia, or lymphoma in the 32P-treated patients was 10% at the 10th year, but increase after that time to reach a value of about 30% at the 20th year, in the surviving case. This risk was not dose-related. Despite a marked reduction of the cumulative 32P dose in the patients maintained by hydroxyurea, the actuarial risk was 19% at the 10th year. In the patients treated exclusively by non radio-mimetic agents (hydroxyurea or pipobroman) a risk of 10% at the 10th year was observed. The risk of carcinoma (excluding skin cancers) was about 15% at the 10th year in the 32P-treated cases, a value similar to that generally reported by the French statistics. There was no prevalence of digestive carcinomas. In contrast, the patients receiving 32P and hydroxyurea as maintenance had an excess risk: 29% at the 10th year. In the relatively young cases treated by non radio-mimetic agents, the risk was similar in both arms: 9% at the 10th year, similar to the expected incidence at this age. The risk of myelofibrosis with myeloid metaplasia was still relatively low at the 10th year, about 15% in all arms, but increased towards a value higher than 30% in the patients surviving at the 20th year. At the present time, but in only a few cases with long-term following, no myelo-fibrosis with splenic metaplasia has been observed in the pipobroman-treated cases. The present results, which need to be confirmed (the present analysis has been done in spring 95) suggest that:-the use of non radio-mimetic agents does not protect against leukemic transformation, which may be a consequence of the disease; rather than of the treatment,-maintenance therapy after initial use of 32P increases the risk of both leukemia and carcinoma,-and hydroxyurea does not delay the risk of developing myelo-fibrosis, in comparison with 32P alone.

[Treatment with hydroxyurea of polycythemia vera in a 11 year-old child]

BACKGROUND

Polycythemia vera is a very rare disease in childhood; its treatment for this reason is not well established.

CASE REPORT

An 11-year-old boy was admitted for polycythemia vera. The three classical major criteria for this condition were present and no cause for secondary polyglobulia could be recognized. The patient was given hydroxyurea. Three years later, he is well with hematocrit below 50%.

CONCLUSIONS

Oral continuous myelosuppressive therapy with hydroxyurea may be proposed in children if there is no HLA-matched family member. Long-term follow-up is nevertheless necessary in order to detect relapse or side-effects of the treatment.

Survival and risk of leukaemia in polycythaemia vera and essential thrombocythaemia treated with oral radiophosphorus: are safer drugs available?

For 366 patients with polycythaemia vera (PV) or essential thrombocythaemia (ET) diagnosed 1971-1990, oral administration of 32-P was used as myelosuppressive treatment. Retreatment was not restricted to any defined interval and the number of treatments or the total dose were not limited. For 107 patients, follow-up was > 10 years. 15 of these presented with life-threatening occlusive vascular symptoms and their survival was short. For the remaining 92 patients 5-yr survival was not significantly worse than for a Swedish population matched for age and sex. Survival at 10 yr was lower, 51% versus 66% expected. Acute myeloid leukaemia (AML) was diagnosed in 11 of the 107 patients (10.3%). In the whole material of 366 patients, 17 have developed AML with a median time of 8.5 yr from start of treatment. There was a maximum incidence of 4% per yr after 8-12 yr. Later, the incidence decreased. The median annual dose of 32-P for the AML patients was 100 MBq and was not significantly larger than for a matched control group surviving without AML, 96 MBq. The results are compared with reports on PV or ET patients treated with busulphan (Bu) or hydroxyurea (HU). With comparable periods of follow-up there are no indications that an adequate myelosuppression with oral 32-P will be associated with shorter survival or higher incidence of AML than treatment with Bu or HU. It is concluded that, for the time being, oral administration of 32-P is an acceptable standard treatment in PV and ET.

Polycythaemia vera and cerebral blood flow: a preliminary study with transcranial Doppler

OBJECTIVES

The purpose of this study has been to investigate by ultrasonographic methods the flow velocities of cerebral arteries because increased blood viscosity due to haematocrit elevation can cause neurological symptoms in polycythaemia vera patients, because of the resulting decrease in cerebral flow.

SUBJECTS AND DESIGN

Twenty newly diagnosed patients, with haemoglobin values of > 18 g dl-1 and/or an haematocrit of > 50%, were examined by transcranial Doppler. Recordings were performed in basal conditions and after pharmacological and/or phlebotomic treatment, when haematocrit values were < or = 50%. Blood velocities were evaluated in middle (MCA), anterior (ACA), posterior (PCA) cerebral arteries and in the basilar (BA) artery.

RESULTS

Basal recordings showed decreased velocities (MCA: 39.40 +/- 9.34 cm s-1; ACA: 34.05 +/- 10.25 cm s-1; PCA: 31.46 +/- 5.97 cm s-1; and BA: 27.47 +/- 7.42 cm s-1); pre- and post-treatment value differences observed in MCA, ACA and BA were highly significant (P < 0.001).

CONCLUSIONS

A decrease in cerebral flow could be a risk for multifocal micro-ischaemic cerebral infarctions leading, after several years, to a multi-infarct dementia; an early reduction in erythrocyte burden should be very useful in polycythaemic patients in preventing lacunar lesions.

Clinical course of essential thrombocythemia in 147 cases

The authors retrospectively analyzed the initial characteristics, treatment, and clinical course in 147 patients with essential thrombocythemia (ET). Median age was 60 years and the M:F ratio was 0.69. At diagnosis, 53 patients were asymptomatic; 50 patients had functional symptoms (mainly vasomotor disturbances); 27 patients had large vessel thrombosis; 27 patients had a bleeding diathesis; and seven patients had both bleeding and thrombosis. The platelet count ranged from 0.7 to 2.92 X 10(12)/l. Forty-five of the 61 tested patients (61%) had prolonged bleeding time and/or platelet hypoaggregation. Three patients had in vitro spontaneous aggregation. No significant correlations were found between hemostatic findings and in vivo bleeding or thrombosis. The incidence of bleeding, however, was higher in patients with more than 2 x 10(12)/l platelets. Of 87 karyotypes performed with banding techniques, only four were abnormal. One hundred twenty-nine patients received one or more cytoreductive agents at diagnosis or during follow-up. Sixty patients received an antiaggregating agent. First-line therapy was radiophosphorus (32P) in 22 patients; busulfan in 35 patients; and hydroxyurea in 72 patients. Hydroxyurea required continuous maintenance therapy and had to be changed to another treatment in 12 of the initial responders because of inadequate control of thrombocythemia. During follow-up, 14 treated patients experienced one or several major thrombotic events. Two untreated patients also had major thrombosis. Only one major bleeding event was seen during follow-up. Median actuarial survival was 73.5% at 7 years and only one patient progressed to acute non-lymphocytic leukemia (ANLL). These results suggest that large vessel thrombosis is the main complication of ET. It appears largely unpredictable in a given patient at diagnosis but can be largely prevented by the control of thrombocythemia. Because of the low incidence of side effects of treatment in this experience, the authors believe that cytoreductive therapy is indicated in most patients with ET, as long as a group of patients with very low risk of thrombosis is not defined in prospective studies.

Second malignancies following cancer therapy

In the absence of proper treatment, essentially all patients with disseminated malignancy and a substantial number of those with more localized disease will die of their cancer. Unfortunately, effective cancer therapy usually results in exposure to treatment that, in itself, may be carcinogenic. The long-term risks attributed to such therapy, however, must be balanced against the benefits of therapy for a life-threatening disease. The risk of treatment-related malignancies is under intensive investigation. As the follow-up time increases on various treatment regimens, our knowledge of these late effects will be advanced significantly.

The iatrogenic leukaemias induced by radio- and/or chemotherapy

A short review, limited to recently published series of data, has been compiled on the 'therapy-induced' secondary malignancies. Their frequency, peak of incidence, haematological and clinical criteria, the influence of age, treated primary disease, choice of drug(s) and modality of prescription and the role of genetic and environmental factors are analyzed. The risk varies between 0.6 and 20.5% after different treatment forms. Some suggestions for the choice of treatment of chronic malignant disorders, and for the design of future epidemiological studies are given.

Treatment-related leukemia in Hodgkin's disease: a multi-institution study on 75 cases

Hematological and cytogenetic characteristics of 75 cases of therapy-related acute non lymphoid leukemia (t-ANLL) occurring in Hodgkin's disease (HD) are analysed in this multi-institution study. Combined radio and chemotherapy had been given in 88 per cent of patients, either as adjuvant (44 per cent) or as salvage modality (44 per cent). Radiotherapy alone and chemotherapy alone had been given in 3 per cent and 9 per cent respectively. Eighty per cent of patients were in remission of HD and 71 per cent off-therapy while developing leukemia. The median latent time from remission of HD to leukemia was 34 months. The myeloblastic variety of leukemia accounted for 43 per cent of total cases; the myelomonocytic and monocytic for 17 per cent and 4 per cent, the promyelocytic and erythroblastic variants for 5 per cent and 7 per cent of t-ANLL. Twenty four per cent of cases were unclassifiable; one of these was TdT-positive. Dysplastic features of erythrocytic line were invariably present with circulating erythroblasts; defects of granulocytes, circulating megathrombocytes and micromegakaryocytes were also present. Bone marrow hypoplasia and marked fibrosis were documented in 47 per cent and 30 per cent of cases. Preleukemia heralded overt leukemia in 73 per cent of cases; 37 per cent had refractory anemia with no excess of blasts; 16 per cent of preleukemias were unclassifiable. Cytogenetics revealed chromosome abnormalities in 83 per cent of cases; 72 per cent presented chromosome 5 and/or 7 monosomy or partial deletion (5q- or 7q-) of the long arm (94 per cent in the combined modality therapy group). In 3 cases, a pure monosomy 7 was observed; in none 5q-alone. Response rate to conventional therapy was 14 per cent; low and high-dose cytarabine were of little benefit. Long-term CR (28 + and 16 + months) was achieved in 2 cases with allogeneic bone marrow transplantation (BMT) as first-line therapy. A better knowledge of t-ANLL in HD and new therapies, including BMT, may improve the prognosis of this late complication of intensive HD treatment.