Treatment of myelodysplastic syndromes with retinoic acid and 1 alpha-hydroxy-vitamin D3 in combination with low-dose ara-C is not superior to ara-C alone. Results from a randomized study. The Scandinavian Myelodysplasia Group (SMG)

Vitamin D Derivatives in Acute Myeloid Leukemia: The Matter of Selecting the Right Targets

Acute myeloid leukemia (AML) is an aggressive and often fatal hematopoietic malignancy. A very attractive way to treat myeloid leukemia, called “differentiation therapy”, was proposed when in vitro studies showed that some compounds are capable of inducing differentiation of AML cell lines. One of the differentiation-inducing agents, all-trans-retinoic acid (ATRA), which can induce granulocytic differentiation in AML cell lines, has been introduced into clinics to treat patients with acute promyelocytic leukemia (APL) in which a PML-RARA fusion protein is generated by a chromosomal translocation. ATRA has greatly improved the treatment of APL. Since 1,25-dihydroxyvitamin D (1,25D) is capable of inducing monocytic differentiation of leukemic cells, the idea of treating other AMLs with vitamin D analogs was widely accepted. However, early clinical trials in which cancer patients were treated either with 1,25D or with analogs did not lead to conclusive results. Recent results have shown that AML types with certain mutations, such as isocitrate dehydrogenase (IDH) mutations, may be the right targets for differentiation therapy using 1,25D, due to upregulation of vitamin D receptor (VDR) pathway.

Effect of Vitamin D on Graft-versus-Host Disease

The different cell subsets of the immune system express the vitamin D receptor (VDR). Through the VDR, vitamin D exerts different functions that influence immune responses, as previously shown in different preclinical models. Based on this background, retrospective studies explored the impacts of vitamin D levels on the outcomes of patients undergoing allogeneic hematopoietic stem-cell transplantation, showing that vitamin D deficiency is related to an increased risk of complications, especially graft-versus-host disease. These results were confirmed in a prospective cohort trial, although further studies are required to confirm this data. In addition, the role of vitamin D on the treatment of hematologic malignancies was also explored. Considering this dual effect on both the immune systems and tumor cells of patients with hematologic malignancies, vitamin D might be useful in this setting to decrease both graft-versus-host disease and relapse rates.

Vitamin D: Effect on Haematopoiesis and Immune System and Clinical Applications

Vitamin D is a steroid-like hormone which acts by binding to vitamin D receptor (VDR). It plays a main role in the calcium homeostasis and metabolism. In addition, vitamin D display other important effects called “non-classical actions.” Among them, vitamin D regulates immune cells function and hematopoietic cells differentiation and proliferation. Based on these effects, it is currently being evaluated for the treatment of hematologic malignancies. In addition, vitamin D levels have been correlated with patients’ outcome after allogeneic stem cell transplantation, where it might regulate immune response and, accordingly, might influence the risk of graft-versus-host disease. Here, we present recent advances regarding its clinical applications both in the treatment of hematologic malignancies and in the transplant setting.

Phosphorylation of Human Retinoid X Receptor α at Serine 260 Impairs Its Subcellular Localization, Receptor Interaction, Nuclear Mobility, and 1α,25-Dihydroxyvitamin D3-dependent DNA Binding in Ras-transformed Keratinocytes

Human retinoid X receptor α (hRXRα) plays a critical role in DNA binding and transcriptional activity through heterodimeric association with several members of the nuclear receptor superfamily, including the human vitamin D receptor (hVDR). We previously showed that hRXRα phosphorylation at serine 260 through the Ras-Raf-MAPK ERK1/2 activation is responsible for resistance to the growth inhibitory effects of 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3), the biologically active metabolite of vitamin D3 To further investigate the mechanism of this resistance, we studied intranuclear dynamics of hVDR and hRXRα-tagged constructs in living cells together with endogenous and tagged protein in fixed cells. We find that hVDR-, hRXRα-, and hVDR-hRXRα complex accumulate in the nucleus in 1α,25(OH)2D3-treated HPK1A cells but to a lesser extent in HPK1ARas-treated cells. Also, by using fluorescence resonance energy transfer (FRET), we demonstrate increased interaction of the hVDR-hRXRα complex in 1α,25(OH)2D3-treated HPK1A but not HPK1ARas cells. In HPK1ARas cells, 1α,25(OH)2D3-induced nuclear localization and interaction of hRXRα are restored when cells are treated with the MEK1/2 inhibitor UO126 or following transfection of the non-phosphorylatable hRXRα Ala-260 mutant. Finally, we demonstrate using fluorescence loss in photobleaching and quantitative co-localization with chromatin that RXR immobilization and co-localization with chromatin are significantly increased in 1α,25(OH)2D3-treated HPK1ARas cells transfected with the non-phosphorylatable hRXRα Ala-260 mutant. This suggests that hRXRα phosphorylation significantly disrupts its nuclear localization, interaction with VDR, intra-nuclear trafficking, and binding to chromatin of the hVDR-hRXR complex.

The role of vitamin D in cancer prevention

Vitamin D, also known as cholecalciferol, is the precursor to the active steroid hormone 1, 25-dihydroxyvitamin D3 (calcitriol; 1, 25(OH)2D3). The main physiological role for 1, 25(OH)2D3 is to regulate calcium and inorganic phosphate homeostasis for bone health. More recently, vitamin D has been investigated for its effects in the prevention and treatment of a variety of diseases such as cancer, autoimmune disorders, and cardiovascular disease. Preclinical data strongly support a role for vitamin D in the prevention of cancer through its anti-proliferative, pro-apoptotic, and anti-angiogenic effects on cells. Epidemiologic and clinical studies have shown mixed data on the correlation between serum vitamin D levels and cancer risk. This report seeks to outline results from the most recent preclinical and clinical studies investigating the potential role of vitamin D in cancer prevention.

The Use of 1α,25-Dihydroxyvitamin D₃ as an Anticancer Agent

The notion that vitamin D can influence the incidence of cancer arose from epidemiological studies. The major source of vitamin D in the organism is skin production upon exposure to ultra violet-B. The very first observation of an inverse correlation between exposure of individuals to the sun and the likelihood of cancer was reported as early as 1941. In 1980, Garland and Garland hypothesised, from findings from epidemiological studies of patients in the US with colon cancer, that vitamin D produced in response to sun exposure is protective against cancer as opposed to sunlight per se. Later studies revealed inverse correlations between sun exposure and the occurrence of prostate and breast cancers. These observations prompted laboratory investigation of whether or not vitamin D had an effect on cancer cells. Vitamin D is not active against cancer cells, but the most active metabolite 1α,25-dihydroxyvitamin D₃ (1,25D) has profound biological effects. Here, we review the anticancer action of 1,25D, clinical trials of 1,25D to date and the prospects of the future therapeutic use of new and low calcaemic analogues.

A phase I study to determine the maximum tolerated dose and safety of oral LR-103 (1α,24(S)Dihydroxyvitamin D2) in patients with advanced cancer

BACKGROUND

The objective of this study was to determine the maximum tolerated dose and safety of LR-103, a Vitamin D analogue, in patients with advanced cancer.

METHODS

In Step A, patients received oral LR-103 once daily in 14-day cycles with intra-patient dose escalation per accelerated dose escalation design. Dose limiting toxicity for Step A was defined as ≥grade 2 hypercalcemia and/or >grade 2 other toxicities. Starting dose was 5 µg/day. Step B used a 3+3 design starting at Step A maximum tolerated dose with 28-day cycles. Dose limiting toxicity was defined as ≥grade 3 hypercalcemia or any grade 3 or 4 non-hematologic toxicity, except hypercalciuria.

RESULTS

Twenty-one patients were enrolled; eight were treated in Step A. At dose level 3 (15 µg/day), two patients had dose limiting toxicity. One had grade 4 hyperuricemia. The other had grade 4 GGT plus grade 3 alkaline phosphatase, fatigue and urinary tract infection (UTI). Dose level 2 (10 µg/day) was the maximum tolerated dose for Step A and was starting dose for Step B. The dose was escalated to dose level 5 (30 µg/day) with a patient experiencing grade 3 dose limiting toxicity of hypercalcemia. The study was discontinued before reaching the maximum tolerated dose due to sponsor decision. Modest increases in serum osteocalcin and calcium and decrease in parathyroid hormone were noted. Best response was stable disease; four patients were on therapy for six months or longer.

CONCLUSION

Step A dose limiting toxicities limited accelerated dose escalation. The maximum tolerated dose of LR-103 was not reached prior to study termination and this agent is no longer being developed.

Perspectives of differentiation therapies of acute myeloid leukemia: the search for the molecular basis of patients' variable responses to 1,25-dihydroxyvitamin d and vitamin d analogs

The concept of differentiation therapy of cancer is ~40 years old. Despite many encouraging results obtained in laboratories, both in vitro and in vivo studies, the only really successful clinical application of differentiation therapy was all-trans-retinoic acid (ATRA)-based therapy of acute promyelocytic leukemia (APL). ATRA, which induces granulocytic differentiation of APL leukemic blasts, has revolutionized the therapy of this disease by converting it from a fatal to a curable one. However, ATRA does not work for other acute myeloid leukemias (AMLs). Since 1,25-dihydroxyvitamin D₃ (1,25D) is capable of inducing monocytic differentiation of leukemic cells, the idea of treating other AMLs with vitamin D analogs (VDAs) was widely accepted. Also, some types of solid cancers responded to in vitro applied VDAs, and hence it was postulated that VDAs can be used in many clinical applications. However, early clinical trials in which cancer patients were treated either with 1,25D or with VDAs, did not lead to conclusive results. In order to search for a molecular basis of such unpredictable responses of AML patients toward VDAs, we performed ex vivo experiments using patient’s blast cells. Experiments were also performed using 1,25D-responsive and 1,25D-non-responsive cell lines, to study their mechanisms of resistance toward 1,25D-induced differentiation. We found that one of the possible reasons might be due to a very low expression level of vitamin D receptor (VDR) mRNA in resistant cells, which can be increased by exposing the cells to ATRA. Our considerations concerning the molecular mechanism behind the low VDR expression and its regulation by ATRA are reported in this paper.

Diagnosis and treatment of primary myelodysplastic syndromes in adults: recommendations from the European LeukemiaNet

Within the myelodysplastic syndrome (MDS) work package of the European LeukemiaNet, an Expert Panel was selected according to the framework elements of the National Institutes of Health Consensus Development Program. A systematic review of the literature was performed that included indexed original papers, indexed reviews and educational papers, and abstracts of conference proceedings. Guidelines were developed on the basis of a list of patient- and therapy-oriented questions, and recommendations were formulated and ranked according to the supporting level of evidence. MDSs should be classified according to the 2008 World Health Organization criteria. An accurate risk assessment requires the evaluation of not only disease-related factors but also of those related to extrahematologic comorbidity. The assessment of individual risk enables the identification of fit patients with a poor prognosis who are candidates for up-front intensive treatments, primarily allogeneic stem cell transplantation. A high proportion of MDS patients are not eligible for potentially curative treatment because of advanced age and/or clinically relevant comorbidities and poor performance status. In these patients, the therapeutic intervention is aimed at preventing cytopenia-related morbidity and preserving quality of life. A number of new agents are being developed for which the available evidence is not sufficient to recommend routine use. The inclusion of patients into prospective clinical trials is strongly recommended.

Vitamin D supplementation and breast cancer prevention: a systematic review and meta-analysis of randomized clinical trials

In recent years, the scientific evidence linking vitamin D status or supplementation to breast cancer has grown notably. To investigate the role of vitamin D supplementation on breast cancer incidence, we conducted a systematic review and meta-analysis of randomized controlled trials comparing vitamin D with placebo or no treatment. We used OVID to search MEDLINE (R), EMBASE and CENTRAL until April 2012. We screened the reference lists of included studies and used the “Related Article” feature in PubMed to identify additional articles. No language restrictions were applied. Two reviewers independently extracted data on methodological quality, participants, intervention, comparison and outcomes. Risk Ratios and 95% Confident Intervals for breast cancer were pooled using a random-effects model. Heterogeneity was assessed using the I² test. In sensitivity analysis, we assessed the impact of vitamin D dosage and mode of administration on treatment effects. Only two randomized controlled trials fulfilled the pre-set inclusion criteria. The pooled analysis included 5372 postmenopausal women. Overall, Risk Ratios and 95% Confident Intervals were 1.11 and 0.74–1.68. We found no evidence of heterogeneity. Neither vitamin D dosage nor mode of administration significantly affected breast cancer risk. However, treatment efficacy was somewhat greater when vitamin D was administered at the highest dosage and in combination with calcium (Risk Ratio 0.58, 95% Confident Interval 0.23–1.47 and Risk Ratio 0.93, 95% Confident Interval 0.54–1.60, respectively). In conclusions, vitamin D use seems not to be associated with a reduced risk of breast cancer development in postmenopausal women. However, the available evidence is still limited and inadequate to draw firm conclusions. Study protocol code: FARM8L2B5L.

The role of vitamin D in hematologic disease and stem cell transplantation

Vitamin D is a steroid hormone with a broad range of biological effects ranging from the classical role as a mediator of calcium and phosphate balance to cellular differentiation and immune modulation. These effects impact normal and dysfunctional hematopoietic and immune function, which may allow an avenue for improved treatment and support of patients suffering from hematologic disorders. In this review, we will summarize the role of vitamin D in normal hematopoiesis, discuss ways in which vitamin D may improve outcomes, and discuss a potential role of vitamin D for treating hematologic disorders and modulating the immune system to improve the outcome of allogeneic stem cell transplant.

Clinical experience using vitamin d and analogs in the treatment of myelodysplasia and acute myeloid leukemia: a review of the literature

Despite progress in understanding the biology of acute myeloid leukemia (AML), and despite advances in treatment, the majority of patients with AML die from the disease. The observation that Vitamin D can induce AML blast cells in vitro to differentiate along the monocytic lineage was made 30 years ago; however, it remains to translate this into a clinically meaningful strategy. This is a review of published clinical experience regarding the use of Vitamin D and its analogs, either alone or in combination with other agents, to treat AML. In many of these reports, investigators included patients with myelodysplasia (MDS) as well as AML patients in their treatment cohorts; therefore reports of Vitamin D and its analogs in treating MDS are included. This review documents heterogeneity in selection criteria for patients treated in these studies, the spectrum of Vitamin D analogs used in various studies, and the differing dosing strategies employed by investigators. Despite examples of occasional clinical efficacy, barriers remain to the successful application of Vitamin D in the treatment of MDS and AML. These include the lack of definition of a particularly sensitive target population, and the as yet unknown optimal choice of Vitamin D analog and dosing schedule.

Vitamin D and cancer: clinical aspects

There are substantial preclinical and epidemiologic data that suggest that vitamin D plays a role in the prevention and treatment of cancer. Numerous observational studies have shown that low blood levels of 25(OH) vitamin D (cholecalciferol), estimated by geographical location, diet and activity assessment or measured serum levels are associated with a higher risk of cancer and worse cancer-specific survival as well as numerous morbidities to e.g. cardiovascular disease, stroke, infection, autoimmune disease, and neuromuscular dysfunction among large populations. A considerable number of in vitro and in vivo studies indicate that the most active metabolite of vitamin D--1,25-dihydroxycholecalciferol or calcitriol--has anti-proliferative, pro-apoptotic, pro-differentiating, and anti-angiogenic properties. Combined treatment of calcitriol and many types of cytotoxic agents has synergistic or at least additive effects. However, clinical trials testing these hypotheses have been less encouraging, though a number of methodological, pharmacological, and pharmaceutical issues confound all trials ever conducted. In order to properly assess the clinical value of vitamin D, its metabolites and analogs in cancer prevention and treatment, more studies are needed.

A systems approach to bone pathophysiology

With evolving interest in multiscalar biological systems one could assume that reductionist approaches may not fully describe biological complexity. Instead, tools such as mathematical modeling, network analysis, and other multiplexed clinical- and research-oriented tests enable rapid analyses of high-throughput data parsed at the genomic, proteomic, metabolomic, and physiomic levels. A physiomic-level approach allows for recursive horizontal and vertical integration of subsystem coupling across and within spatiotemporal scales. Additionally, this methodology recognizes previously ignored subsystems and the strong, nonintuitively obvious and indirect connections among physiological events that potentially account for the uncertainties in medicine. In this review, we flip the reductionist research paradigm and review the concept of systems biology and its applications to bone pathophysiology. Specifically, a bone-centric physiome model is presented that incorporates systemic-level processes with their respective therapeutic implications.

A novel Gemini vitamin D analog represses the expression of a stem cell marker CD44 in breast cancer

CD44 is a multifunctional transmembrane protein involved in cell proliferation, angiogenesis, invasion, and metastasis. CD44 is identified as a cancer stem cell marker, and the CD44-positive breast cancer cells are enriched in residual breast cancer cell populations after conventional therapies, suggesting that CD44 may be an important target for cancer prevention and therapy. Therefore, we investigated for the inhibitory effect of a novel Gemini vitamin D analog, 1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124), on mammary tumor growth and CD44 expression in MCF10DCIS.com human breast cancer in vitro and in vivo. MCF10DCIS.com cells were injected into mammary fat pads in immunodeficient mice, and BXL0124 was then administered intraperitoneally (0.1 μg/kg body weight) or orally (0.03 or 0.1 μg/kg body weight) 6 days a week for 5 weeks. At necropsy, mammary tumors and blood were collected for evaluating tumor growth, CD44 expression, and serum calcium level. BXL0124 suppressed mammary tumor growth and markedly decreased the expression of CD44 protein in MCF10DCIS xenograft tumors without causing hypercalcemic toxicity. BXL0124 also inhibited the expression of CD44 protein and mRNA as well as the transcriptional activity of the CD44 promoter in cultured MCF10DCIS.com cells. The repression of CD44 expression induced by BXL0124 was blocked by siRNA vitamin D receptor (VDR), indicating that the regulation of CD44 expression by BXL0124 is a VDR-dependent event. The novel Gemini vitamin D analog, BXL0124, represses CD44 expression in MCF10DCIS.com cells in vitro and in xenograft tumors, suggesting an inhibitory role of a Gemini vitamin D derivative on breast cancer stem cells.

Differentiation therapy of leukemia: 3 decades of development

A characteristic feature of leukemia cells is a blockade of differentiation at a distinct stage in cellular maturation. In the 1970s and 1980s, studies demonstrating the capabilities of certain chemicals to induce differentiation of hematopoietic cell lines fostered the concept of treating leukemia by forcing malignant cells to undergo terminal differentiation instead of killing them through cytotoxicity. The first promising reports on this notion prompted a review article on this subject by us 25 years ago. In this review, we revisit this interesting field of study and report the progress achieved in the course of nearly 3 decades. The best proof of principle for differentiation therapy has been the treatment of acute promyelocytic leukemia with all-trans retinoic acid. Attempts to emulate this success with other nuclear hormone ligands such as vitamin D compounds and PPARgamma agonists or different classes of substances such as hematopoietic cytokines or compounds affecting the epigenetic landscape have not been successful on a broad scale. However, a multitude of studies demonstrating partial progress and improvements and, finally, the new powerful possibilities of forward and reverse engineering of differentiation pathways by manipulation of transcription factors support the continued enthusiasm for differentiation therapy of leukemia in the future.

Vitamin D signalling pathways in cancer: potential for anticancer therapeutics

Epidemiological studies indicate that vitamin D insufficiency could have an aetiological role in various human cancers. Preclinical research indicates that the active metabolite of vitamin D, 1alpha,25(OH)2D3, also known as calcitriol, or vitamin D analogues might have potential as anticancer agents because their administration has antiproliferative effects, can activate apoptotic pathways and inhibit angiogenesis. In addition, 1alpha,25(OH)2D3 potentiates the anticancer effects of many cytotoxic and antiproliferative anticancer agents. Here, we outline the epidemiological, preclinical and clinical studies that support the development of 1alpha,25(OH)2D3 and vitamin D analogues as preventative and therapeutic anticancer agents.

Calcitriol in cancer treatment: From the lab to the clinic

1,25-Dihydroxyvitamin D (calcitriol), the most active metabolite of vitamin D, has significant antineoplastic activity in preclinical models. Several mechanisms of activity have been proposed. These include inhibition of proliferation associated with cell cycle arrest and, in some models, differentiation, reduction in invasiveness and angiogenesis, and induction of apoptosis. Proposed mechanisms differ between tumor models and experimental conditions, and no unifying hypothesis about the mechanism of antineoplastic activity has emerged. Synergistic and/or additive effects with cytotoxic chemotherapy, radiation, and other cancer drugs have been reported. Significantly supraphysiological concentrations of calcitriol are required for antineoplastic effects. Such concentrations are not achievable in patients when calcitriol is dosed daily due to predictable hypercalcemia and hypercalcuria; however, phase I trials have demonstrated that intermittent dosing allows substantial dose escalation and has produced potentially therapeutic peak calcitriol concentrations. Recently, a phase II study reported encouraging levels of activity for the combination of high-dose calcitriol and docetaxel administered on a weekly schedule in patients with androgen-independent prostate cancer. This regimen is now under study in a placebo-controlled randomized trial in androgen-independent prostate cancer and in phase II studies in several other tumor types. Further work is needed to elucidate the molecular mechanisms of antineoplastic activity and optimal clinical applications of calcitriol in cancer.

Malignancy: Current Clinical Practice: Current Therapeutic Options in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are characterized initially by ineffective hematopoiesis and subsequently the frequent development of acute myelogenous leukemias (AML). During the last 15 years, important progress has been made in the understanding of the biology and prognosis of myelodysplastic syndromes. Risk-adapted treatment strategies were established due to the high median age (60-75 years) of MDS-patients and the individual history of the disease (number of cytopenias, cytogenetical changes, transfusion requirements). The use of allogeneic bone marrow transplantation for MDS patients currently offers the only potentially curative treatment, but this treatment modality is not available for the most of the "typical" MDS-patients aged >60 years. Based on in-vitro findings analyzing the potential of several agents to differentiate or to stimulate hematopoietic progenitor cells a number of therapeutic options were evaluated in clinical trials: hematopoietic growth factors (e.g. erythropoietin, G-CSF), differentiation inducers (e.g. retinoids), or cytoprotective substances (amifostine). The role of immunsuppressive agents (antithymocyte globulin, cyclosporine A) either alone or in combination is being actively investigated. Using intensive cytotoxic treatment in patients with advanced MDS or AML after MDS complete remission rates comparable with those known from the treatment of de novo AML were reported. The therapy related toxicity (early death rate <10%) was reduced by using G-CSF given prior ("Priming") and/or after the cytotoxic treatment.

Oral 9-cis retinoic acid (Alitretinoin) in the treatment of myelodysplastic syndromes: results from a pilot study

A multicenter phase II study was initiated to investigate the efficacy, toxicity and tolerability of an oral regimen of 9-cis retinoic acid (9CRA) as a differentiation-inducing agent stimulating both retinoic acid receptor (RAR) and retinoic X receptor (RXR). Thirty patients with myelodysplastic syndromes (MDS) were enrolled into the study. The MDS subtypes were distributed as follows: 14 refractory anaemia (RA), four refractory anaemia with ringed sideroblasts (RARS), and 12 refractory anaemia with excess blasts (RAEB). The age ranged from 40 to 81 years (median 70). None of these had previously received treatment for MDS other than supportive therapy. 9CRA (Alitretinoin capsules, kindly provided by Allergan-Ligand Retinoid Therapeutics) was given daily at 60 mg/m2 p.o. for 1 week, followed by an intra-patient escalation to 100 mg/m2 during the second week, up to a maximum of 140 mg/m2. The planned treatment duration was 48 weeks. Twenty-five were available for assessment. One patient (4%) with RA achieved complete hematological remission. Four (16%), two with RA, two with RAEB, had minor responses resulting in decreased transfusion requirements or increased neutrophils. Thus, the overall response rate was 20% in evaluable patients with MDS and 17% in the study group on an intention-to-treat basis. The most frequent side-effects included headache (77%), dry skin (57%), arthralgias (30%), and rash (23%). In conclusion, although modest responses were noted in this study, the treatment tolerability was suboptimal. It is conceivable that a lower dosage schedule may be efficacious and better tolerated so enabling prolonged exposure which may be required to induce a differentiation effect.

Combined differentiating therapy for myelodysplastic syndromes: a phase II study

An in vitro synergism between different inducers of AML cell differentiation has been previously observed. Therefore, we treated 53 myelodysplastic (MDS) patients with a low dose combination of cis-retinoic acid (cRA, 20-40 mg/day) and 1,25 alpha (OH)2 cholecalciferol [(OH)2D3, 1-1.5 micrograms/day] +/- intermittent 6-thioguanine (30 mg/m2/day). The latter was reserved for patients with bone marrow (BM) blast excess (> or = 5%). The treatment was well tolerated, without major toxicity. Among 25 patients with BM blasts less than 5%, we observed one complete, eight partial and four minor responses (response rate 52%) with a median response duration of 8 months (2 +/- 24). Median survival, which did not correlate with response, is projected at 76 months. Thirty-one patients with BM blast excess (> or = 5%), including three of the previous group who progressed to refractory anemia with excess of blasts (RAEB), were treated with the three-drug protocol. One complete, 12 partial and six minor responses were obtained (response rate 61%) with a median response duration of 6 months (2-29+). A significant difference in survival (P < 0.005) was observed between the 19 responders (median 25 months) and the 12 non-responders (median 9 months). A reduction in the transfusion need was observed in 41% of the transfusion-dependent patients with blast excess and in 53% of those without blast excess. Therefore, combined differentiating therapy seems more effective than previously reported single agent treatments and should be considered for a larger randomized study to assess its actual impact on survival of MDS patients.

Treatment of 34 patients with myelodysplastic syndromes with 13-CIS retinoic acid

Thirty-four patients with myelodysplastic syndromes, 23 men and 11 women, aged between 47 and 80 years, with all types of myelodysplastic syndromes were treated with 13-cis-retinoic acid. The dose of retinoic acid ranged between 10 and 60 mg/m2/daily and was administered in combination with vitamin E to diminish side effects. The duration of treatment was 3 months to 5 years. Partial remission was achieved in 4 patients, 1 with RA type, 2 with RAEB and 1 with CMML. Survival ranged from 1 to 5 years. Patients who received retinoic acid developed mild side effects. In conclusion, the administration of 13-cis-retinoic acid improves the hematological picture in a small number of MDS patients (11.7%).

Low-dose ARA-C consistently induces hematologic responses in the clinical 5q- syndrome

Five patients with the classical clinical syndrome associated with a deletion of the long arm of chromosome 5, i.e., anemia, macrocytosis, and thrombocytosis, or a normal platelet count, were treated successfully with subcutaneous low-dose cytosine arabinoside (LDARA-C). Prior therapy with other drugs had failed in four of the five patients. A total of nine complete and one partial hematologic responses were induced in five patients. Duration of the first hematologic response ranged from 3 to 30+ months. Two patients (cases 3 and 4) continue in their first hematologic response at 29 and 30 months. Upon relapse, up to three responses could be reinduced in two patients. Duration of the subsequent hematologic responses in case 1 was 16, 8, and 10 months and case 2 achieved two responses of 15 and 18+ months duration. LDARA-C therapy was associated with mild to severe neutropenia and moderate to severe thrombocytopenia. Thus, subcutaneous LDARA-C is highly effective in the treatment of patients with myelodysplasia associated with deletion of the long-arm of chromosome 5 (5q-).

Low-dose ara-C in myelodysplastic syndromes (MDS) and acute leukemia following MDS: proposal for a predictive model

Patients with myelodysplastic syndromes (MDS) comprise an extremely heterogeneous group. There is a need for decision models both for predicting the natural course of the disease and the outcomes of different treatment alternatives. In 102 consecutive patients with MDS or acute myelogenous leukemia (AML) following MDS, pre-treatment variables were studied in relation to the response to treatment with low-dose ara-C. Thirty patients (29%) responded with either a complete remission or a significant rise in the hemoglobin level. For the remaining 71%, the treatment was ineffective and in some cases hazardous. The factors associated with a poor response to treatment could be divided into two groups: one included low platelet counts and the presence of chromosomal aberrations, both signs of progressive MDS with a short survival, and the other comprised morphological findings, indicating ineffective hemopoiesis. Patients with platelet counts > 150 x 10(9)/l had a response rate of 55%, compared to 24% in patients with subnormal platelet counts. Logistic regression identified low bone marrow cellularity, absence of ring sideroblasts and < 2 chromosomal aberrations as predictors of a favourable response in patients with platelet counts < 150 x 10(9)/l. These factors and the platelet count were combined in a predictive model which divided patients into three groups with different probabilities of response: one favourable (38% of the patients), with a response rate of > 50%; a second, intermediate group (33% of the patients), with a response rate of 24%; and a third, unfavourable group (29% of the patients) with only 3% responses.(ABSTRACT TRUNCATED AT 250 WORDS)

A combination of granulocyte colony-stimulating factor and erythropoietin may synergistically improve the anaemia in patients with myelodysplastic syndromes

In an attempt to obtain a synergistic effect on the hemoglobin levels in anaemic patients with myelodysplastic syndromes (MDS), granulocyte colony-stimulating factor (G-CSF) and erythropoietin (epo) were combined in a clinical phase II trial. Twenty-two patients with MDS were included in the study. G-CSF was given alone for six weeks and then in combination with epo for the following twelve weeks. Eight (38%) of 21 evaluable patients showed a significant increase in hemoglobin. One patient with a previous response and subsequent failure to epo alone improved after the addition of G-CSF. Responses were more frequent in patients with less advanced pancytopenia, lower endogenous levels of serum-epo and in those with ring sideroblasts in the bone marrow. The response frequency of 38% is higher than in any study of epo as monotherapy. Moreover, patients with ring sideroblasts, who respond poorly to epo alone, showed a response rate of 60%. Our findings suggest a synergistic in vivo effect of granulocyte-CSF and erythropoietin in patients with myelodysplastic syndromes.

New uses for old vitamins. The treatment of myelodysplastic disorders

The treatment of myelodysplastic disorders with vitamins A and D or derivatives and nutrients has been less than satisfactory. Combinations of vitamin D3 and 13-CRA with or without cytosine arabinoside appear to offer no advantage over any of the single agents alone. Until other vitamin D derivatives are developed that are effective but do not cause hypercalcemia, vitamin D3 cannot be recommended for the treatment of MDS. 13-CRA has been shown to be effective in some patients with MDS; however, it cannot be recommended as standard therapy because of the conflicting data cited above. Further clinical trials with 13-CRA perhaps in combination with vitamin E or colony-stimulating factors are clearly indicated for this disease for which we have no effective therapy.

Retinoids in cancer treatment

Since initial studies identifying the important role of vitamin A and its derivatives (retinoids) in maintaining the integrity of epithelial tissues, these compounds have served as paradigms for experimental studies exploring the pharmacologic modification of carcinogenesis. Retinoids have clearly been shown to inhibit chemically induced mammary and urothelial carcinogenesis in experimental animals. Prohibitive toxicity of the parent compound, vitamin A, led to a systematic search for synthetic derivatives with an improved therapeutic index. More than 1500 such compounds have been synthesized, many retaining chemopreventive potential, but with less toxicity. Although several anecdotal reports confirming therapeutic benefits of cis-retinoic acid in patients with acute promyelocytic leukemia and myelodysplastic syndromes appeared in the late 1970s and early 1980s, the remarkable studies of Huang and his colleagues in China in 1988 reporting complete remissions in patients with this uncommon variety of acute myelogenous leukemia with the transisomer of retinoic acid (all-trans-retinoic acid) led to a resurgence of interest in the retinoids as differentiating agents for the prevention and therapy of cancer. Furthermore, molecular studies showing DNA rearrangements of the alpha nuclear receptor for retinoic acid located on chromosome 17 in patients with acute promyelocytic leukemia, a disease invariably associated with a translocation between chromosomes 15 and 17, provided a direct connection between an altered nuclear receptor and the development of a human malignancy. The retinoids also may have important beneficial effects in prevention of recurrent malignancies once the primary tumor has been treated, such as in squamous cell carcinoma of the head and neck. Because retinoids appear to be less effective in inducing differentiation in nonpromyelocytic leukemia cells, investigators have conducted a number of studies to exploit potential synergism between retinoids and other differentiating agents or biologic effectors. Differentiation therapy and chemoprevention are attractive alternative approaches to intensive cytotoxic chemotherapy. It is now clear that retinoids represent one class of compounds with which it may be possible to reverse the progression of malignant disease and prevent carcinogenesis.

A predictive model for the clinical response to low dose ara-C: a study of 102 patients with myelodysplastic syndromes or acute leukaemia

The response to treatment with low-dose ara-C was studied in 102 consecutive patients; 79 with myelodysplastic syndrome (MDS) and 23 with acute myelogenous leukaemia (AML) following MDS. The aim was to find variables that could predict the response to treatment. All patients had clinical symptoms related to cytopenia. Peripheral blood values, bone marrow morphology histology and chromosomes were analysed before the start of treatment. The median survival of the patients was 9 months and a poor survival was predicted by advanced age, low platelet counts, the presence of pseudo-Pelger morphology and > or = 2 chromosomal aberrations. Thirty patients (29%) responded with either a complete remission or a significant increase in haemoglobin level. For the remaining 71%, the treatment was ineffective and in some cases hazardous. The factors associated with a poor response to treatment could be divided into two groups: one included low platelet counts and the presence of chromosomal aberrations, both signs of progressive MDS with a short survival, and the other comprised morphological findings, indicating ineffective haemopoiesis. Patients with platelet counts > 150 x 10(9)/l had a response rate of 55% compared to 23.5% in patients with subnormal platelet counts. Logistic regression identified low bone marrow cellularity, absence of ring sideroblasts and < 2 chromosomal aberrations as predictors of a favourable response in patients with platelet counts < 150 x 10(9)/l. These factors and the platelet count were combined in a predictive model which can divide patients into three groups with different probabilities of response: a favourable group, 38.6% of the patients, with a response rate of > 50%, an intermediate group, 32.7% of the patients, with a response rate of 24%, and an unfavourable group, 28.7% of the patients, with only 3% responses. While low-dose ara-C is an effective treatment for some patients, it is ineffective and hazardous for others. We present a model that can facilitate therapeutic decision making in two-thirds of patients with MDS and MDS-AML by identifying patients who should not be treated with low-dose ara-C as well as patients with a relatively high probability of response.

The effect of retinoic acid on chemosensitivity of PA-1 human teratocarcinoma cells and its modulation by an activated N-ras oncogene

Combination of chemotherapeutic drugs with agents that induce cell differentiation is a possible means of improving cancer chemotherapy. To explore this approach we used 4 cell lines established from the human teratocarcinoma-derived cell line PA-1; 2 retinoic acid (RA)-sensitive lines compared to 2 RA-resistant lines transformed by an activated N-ras oncogene. Equal numbers of colony-forming cells were exposed for 72 hr to 10(-6)M RA and subsequently to a range of concentrations of cisplatinum, etoposide or bleomycin. Enhanced cytotoxicity of cisplatin and etoposide (3- to 5-fold) was observed in the N-ras-transformed cell lines compared to the non-transformed lines. Treatment with RA caused an increase in the cytotoxicity of all 3 drugs to the 2 RA-sensitive cell lines. In contrast, a reduction of cytotoxicity was observed in the 2 N-ras-transformed lines. Our results indicate that sensitivity to cytotoxic agents can be increased by RA in RA-sensitive cells, but the opposite effect is seen in N-ras transformed, RA-resistant cells. Therefore, a general rationale for combination therapy with RA and cytotoxic drugs cannot be inferred.

Myelodysplastic syndromes. Pathogenesis, diagnosis and treatment

Our understanding of the biology of leukemia and myelodysplasia is still only partial. The diagnosis of myelodysplasia is often based on quantitative and qualitative findings in the peripheral blood and bone marrow. These findings are often shared by other disorders. There is a need for sensitive and inexpensive laboratory tests to determine clonality and karyotypic abnormalities in this disorder. Future classifications of these syndromes will need to be based on morphologic and biologic markers that are closely linked to disease progression, response to treatment, and survival. Our limited understanding of the pathogenesis of MDS decreases the specificity and effectiveness of our therapeutic interventions. Agents that are minimally toxic such as CRA, danazol, 1,25-dihydroxyvitamin D3, androgens, and pyridoxine are seldom useful. Antileukemic therapy and allogeneic bone marrow transplantation have a major role to play in patients younger than 45 years of age; in older patients these treatment modalities remain controversial because of their toxicity. Hematopoietic growth factors, used alone or in combination, may improve the quality of life and improve survival of patients with MDS. Growth factors may also decrease treatment-related mortality associated with chemotherapy and bone marrow transplantation and render these treatment modalities available for a higher percentage of patients. The development of more specific differentiating agents may permit hematopoietic differentiation while minimizing side effects.

Therapy of 'high risk' myelodysplastic syndromes with an association of low-dose Ara-C, retinoic acid and 1,25-dihydroxyvitamin D3

Forty-four patients with high risk primary myelodysplastic syndromes and an excess of marrow blasts were treated with a combination of low-dose Ara-C, retinoic acid and vitamin D3. Morphological subtypes were refractory anemia with excess of blasts (RAEB) in 16, RAEB in transformation (RAEB-T) in 20 and chronic myelomonocytic leukemia (CMML) in eight patients. The therapy was continued in responders until relapse or death. The results were compared to those of a matched control of 44 patients given a supportive therapy only. In the treated group the overall response rate was 50% (75% in RAEB, 50% in RAEB-T and 0% in CMML) and the survival was significantly better than in the control group (P < 0.025). Comparing separately each FAB subgroup gave statistical evidence that the treatment prolonged the survival in the RAEB-T subgroup only (P < 0.002). The median duration of response was 15 months and the survival in responders was statistically better than in non-responders (P < 0.0001). Myelosuppression has been the most important side effect, however, no death related to the treatment was observed. Our study suggests that patients with RAEB-T, who are not suitable candidates for aggressive chemotherapy, could benefit from our treatment schedule. The long duration of therapy seems to be of value for patients achieving a response in order to prolong the survival. The toxicity is acceptable and the therapy can be given on an outpatient basis.