Subcutaneous granulocyte-macrophage colony-stimulating factor in patients with myelodysplastic syndrome: toxicity, pharmacokinetics, and hematological effects

Correlations between inflammatory cytokine levels and degree of pigmentation in acral melanomas

Cutaneous melanoma, a highly aggressive skin tumor, is characterized by complex signaling pathways in terms of its pathogenesis and progression. Although the degree of pigmentation in melanoma determines its progression, metastasis, and prognosis, its association with inflammatory cytokines remains unclear. Thus, we evaluated the associations between melanoma pigmentation and plasma levels of inflammatory cytokines; furthermore, we investigated the potential variations in this relationship across the primary anatomic sites of melanoma. We enrolled patients with cutaneous melanoma who visited Chonnam National University Hwasun Hospital between January 2021 and December 2021. The anatomical sites of melanoma were categorized as acral and non-acral sites. The degree of pigmentation was quantified using computer software. In total, nine inflammatory cytokines were analyzed, including interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, IL-13, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α). This study included 80 melanoma patients. Of these, 53 had acral melanoma and 27 had non-acral melanoma. Overall, plasma concentrations of IL-2, IL-4, IL-5, GM-CSF, and IFN-γ demonstrated significant correlations with diminished pigmentation. Furthermore, in the acral melanoma patients group, plasma concentrations of IL-2, IL-4, IL-5, GM-CSF, IFN-γ, and TNF-α revealed significant correlations with diminished pigmentation. Our results reveal significant associations between melanoma pigmentation and various cytokine levels, particularly in acral melanoma patients; these associations can be influenced by factors related to acral melanoma, such as physical stress or trauma. These correlations may also provide directions for the treatment of acral melanoma.

An update on GM-CSF and its potential role in melanoma management

GM-CSF drives the differentiation of granulocytes and monocyte/macrophages from hematopoietic stem cell progenitors. It is required for differentiating monocytes into dendritic cells (DC). Although approved for recovery of granulocytes/monocytes in patients receiving chemotherapy, G-CSF is preferred. Enthusiasm for GM-CSF monotherapy as a melanoma treatment was dampened by two large randomized trials. Although GM-CSF has been injected into tumors for many years, the efficacy of this has not been tested. There is a strong rationale for GM-CSF as a vaccine adjuvant, but it appears of benefit only for strategies that directly involve DCs, such as intratumor talimogene laherparepvec and vaccines in which DCs are loaded with antigen ex vivo and injected admixed with GM-CSF.

Biological Effects of Anti-Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) Antibody Formation in Patients Treated With GM-CSF (Sargramostim) as Adjuvant Therapy of Melanoma

OBJECTIVES

We investigated the development of binding and neutralizing antibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients receiving prolonged therapy with GM-CSF as adjuvant therapy of melanoma and the impact of these antibodies on biological effects.

METHODS

Fifty-three patients with high-risk melanoma that had been surgically excised were treated with GM-CSF, 125 μg/m daily for 14 days every 28 days for 1 year after surgical resection of disease. Serum samples for antibodies to GM-CSF were measured before treatment and on study days 155 and 351. Blood draws for testing biological effects were keyed to GM-CSF administration: days 0 (before), 15 (after 14 d on GM-CSF), 29 (after 14 d off GM-CSF), 155, and 351 (after 14 d on GM-CSF in the sixth and 13th cycle of treatment).

RESULTS

Of 53 patients enrolled, 43 were evaluable for the development of anti-GM-CSF antibodies. Of these, 93% developed binding antibodies and 42% developed both binding and neutralizing antibodies. The increase in the white blood cell count, percent eosinophils, or neopterin levels engendered by GM-CSF administration was abrogated or markedly decreased in patients with neutralizing antibodies but not in patients who developed only binding antibodies.

CONCLUSIONS

Ninety-three percent of patients with melanoma treated with GM-CSF as adjuvant therapy develop antibodies to GM-CSF. In those with neutralizing antibodies, a diminution of the biological effects of GM-CSF was observed. The development of neutralizing antibodies might also abrogate the potential clinical benefit of this treatment and should be considered in the design of future clinical trials.

Recombinant Hemopoietic Growth Factors: Comparative Hemopoietic Response in Younger and Older Subjects

OBJECTIVE

To study the effectiveness of hemopoietic growth factors in older patients.

DESIGN

Literature review. All articles published in English language between 1987 and 1990 were reviewed. Those reporting studies without age limits as entry criteria and describing the effects of growth factors in individual patients were suitable for analysis. Bone marrow transplantation related articles were excluded.

MAIN OUTCOME MEASURES

The meanfold increase of granulocytes for Granulocyte-Colony Stimulating Factor, Granulocyte Macrophage-Colony Stimulating Factor, and Interleukin 3 and of hemoglobin for erythropoietin were compared in subjects younger and older than 65, by Mann-Whitney U test.

RESULTS

Of 68 studies, 23 were suitable for analysis. These included patients with myelodysplastic syndromes, aplastic anemia, chemotherapy-induced myelosuppression, chronic granulocytopenia, anemia, and myelosuppression of malignancies and of chronic disease. Of 204 patients, 67 were 65 years of age or older and 42 were over 70. No difference was seen in meanfold increase of granulocyte and hemoglobin in time of response to growth factors or in response in presence of an absolute neutrophil count lower than 1000/microliters between younger and older patients.

CONCLUSION

Early response to hemopoietic growth factors appears well maintained with advanced age. Prospective studies of the prolonged effects of these factors in older and younger patients are needed.

TOA02, a recombinant adenovirus with tumor-specific granulocyte macrophage colony-stimulating factor expression, has limited biodistribution and low toxicity in rhesus monkeys

TOA02 is a genetically modified oncolytic adenovirus that contains human granulocyte macrophage colony-stimulating factor (hGM-CSF). It has been verified in vitro that TOA02 can specifically replicate in tumor cells that possess high telomerase reverse transcriptase activity and Rb pathway deficiency. However, the replication specificity, hGM-CSF expression, and toxicity of TOA02 in vivo are still unknown. Therefore, the biosafety of TOA02 remains a critical issue before its potential clinical use. In this study, viral replication and hGM-CSF expression levels were investigated in both xenograft nude mouse models and rhesus monkeys, and chronic toxicity was evaluated in rhesus monkeys. Our results show that (1) the replication and hGM-CSF expression of TOA02 are high in tumor model, (2) there are no hGM-CSF expression and continuous viral replication in rhesus monkeys except in pancreas and epididymis, and (3) the antiadenovirus antibody was positive in the chronic toxicity experiment, but pathological change of blood cytology and blood biochemistry were not found. There were no other histopathology lesions apart from skin inflammation of the administration region, lymphadenitis of draining lymph nodes. Our findings suggest that TOA02 is relatively safe for in vivo application, thus laying the foundation for future clinical trials with TOA02.

The potential role of recombinant hematopoietic colony-stimulating factors in preventing infections in the immunocompromised host

Hematopoietic colony-stimulating factors coordinate the proliferation and maturation of bone marrow and peripheral blood cells during normal hematopoiesis. Most of these factors are now available as recombinant human colony-stimulating factors, and preclinical and clinical testing is proceeding rapidly. Granulocyte and granulocyte/macrophage colony-stimulating factors have been the most extensively studied to date. In human clinical trials, granulocyte colony-stimulating factor improves neutrophil counts and function, reduces episodes of febrile neutropenia, improves neutrophil recovery after disease- or treatment-induced myelosuppression, and reduces the number of serious infections in several neutropenic disease states. Granulocyte/macrophage colony-stimulating factor has similar biological properties but may also improve eosinophil proliferation and function, and platelet cell recovery after myelotoxic bone marrow injury, Interleukin-1 boosts the effects of granulocyte colony-stimulating factor and granulocyte/macrophage colony-stimulating factor, but also may promote the resolution of established infections in conjunction with antibiotics. The therapeutic realities and future therapeutic implications of these agents for the therapy of infections, cancer and hemopoietic disorders are discussed.

G- and GM-CSF in oncology and oncological haematology

Administration of G- and GM-CSF increases the neutrophil counts in a number of clinical situations. GM-CSF shows the additional effect of increasing the number of monocytes and eosinophil granulocytes. Both G- and GM-CSF affect of neutrophil functions, in the case of GM-CSF there are some potentially negative effects on neutrophil migration and adhesiveness. The clinical relevance of the various effects on mature haematopoietic cells is not fully understood. Clinical data with G-CSF treatment indicate that increased levels of neutrophil granulocytes following cytotoxic chemotherapy may translate into clinical benefit such as a decreased rate of neutropenic infection and an increased cytotoxic chemotherapy dose even though the data are conflicting and the risk of "laboratory cosmetics" is apparent. Regarding treatment with GM-CSF following chemotherapy, the clinical benefit is unclear. The clinical benefit of GM-CSF-induced monocytes and eosinophils is unknown. G- and GM-CSF accelerates neutrophil recovery following autologous or allogeneic BMT. The influence on neutropenic infections is, however, less impressive. Pretreatment with G- or GM-CSF increases the yield of peripheral stem cell harvest, thereby reducing the number of leukaphereses needed. Transplantation of G- and GM-CSF primed autologous peripheral stem cells tends to reduce the period of post-transplant cytopenia, particularly thrombocytopenia, in comparison with traditional ABMT. In patients with MDS, G- and GM-CSF appear to increase the number of neutrophil granulocytes and there is some evidence that patients with severe infectious problems will benefit from this treatment. However, little influence was seen on the main clinical problems with these patients, which are anaemia and thrombocytopenia. In conclusion, G- and GM-CSF are two different proteins with different properties in vivo and in vitro. GM-CSF has, compared with G-CSF, more complex pharmacological effects and a more trouble-some side-effect profile. Early clinical development indicates that both compounds have a substantial influence on the levels of certain blood cells. Whether the increases in different blood cells translate into long-term clinical benefit for greater patient groups is the focus of ongoing research. The effects of G- and GM-CSF may be potentiated by other cytokines, an area which is presently being explored.

Influence of varying doses of granulocyte-macrophage colony-stimulating factor on pharmacokinetics and antibody-dependent cellular cytotoxicity

Recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) is used in immunotherapy for correction of neutropoenia. The optimal dose for activation of immune functions and the pharmacokinetics following repeated administrations is less analysed in depth. In this study, the pharmacokinetics and the effects on haematological functions and antibody-dependent cellular cytotoxicity (ADCC) were analysed in 50 patients with metastatic colorectal carcinoma receiving monoclonal antibody based therapy in combination with Escherichia coli-derived GM-CSF (molgramostim) administered s.c. once daily for 10 days every month over a period of 4 months. Thirty-three patients received a GM-CSF dose of 200-250 microg/m(2)/day. Seventeen patients received GM-CSF doses varying between 65 and 325 microg/m(2)/day in the different treatment cycles. Serum GM-CSF concentration was measured (ELISA) before and 3-4 h after (peak serum concentration) GM-CSF administration days 1, 5 and 10. Prior to therapy, GM-CSF was not detectable in serum. Following repeated daily administrations, the peak serum concentration of GM-CSF gradually decreased on days 5 and 10 compared to day 1 (P < 0.05). During a 10-day treatment cycle, the total number of leukocytes, neutrophils, eosinophils, monocytes and lymphocytes increased. A dose-dependent increment in total white blood cell count and neutrophils was observed. The total numbers of GM-CSF receptor (alpha-subunit) expressing cells (granulocytes and monocytes) increased significantly during treatment while a transient decline in expression intensity was observed at day 5, suggesting a receptor-mediated removal of GM-CSF as a mechanism for the elimination of GM-CSF from circulation. ADCC of peripheral mononuclear cells was decreased at day 10 compared to baseline. An inverse correlation between the dose and ADCC was noted. The data might indicate that high doses of GM-CSF may have a negative impact on ADCC.

Granulocyte and granulocyte macrophage colony-stimulating factors as therapy in human and veterinary medicine

Granulocyte colony-stimulating factors (G-CSFs) and granulocyte macrophage colony-stimulating factors (GM-CSFs) are endogenous cytokines that regulate granulocyte colonies and play a major role in the stimulation of granulopoiesis (neutrophils, basophils and eosinophils) and in the regulation of microbicidal functions. There are numerous pathological conditions in which neutrophils are decreased, the most common being neutropenia associated with cancer chemotherapy, which increases the risk of serious microbial infections developing with the potential for high morbidity and mortality. New methods in molecular biology have led to the identification and cloning of CSF genes and biopharmaceutical production. Since then, CSFs have been widely used for the prevention and treatment of neutropenia associated with cancer chemotherapy, for mobilising haematopoietic cell precursors, and for other neutropenia-related pathologies. This review focuses on the use of CSFs within both human and veterinary medicine. Clinical applications, pharmacology, tolerability and the potential role of these factors in veterinary medicine are considered.

The myelodysplastic syndromes: diagnosis and treatment

The myelodysplastic syndromes (MDSs) are common, acquired, clinically challenging hematologic conditions that are characterized by bone marrow failure and a risk of progression to acute leukemia. These disorders can arise de novo, especially in elderly patients or, less often, as a consequence of prior chemotherapy or radiotherapy for an unrelated disease. The MDS classification systems were revised recently and updated. These refined classification and prognostic schemes help stratify patients by their risk of leukemia progression and death; this knowledge can help clinicians select appropriate therapy. Although many treatments for MDS have been proposed and evaluated, at present, only hematopoietic stem cell transplantation offers any real hope for cure, and no available therapy beyond general supportive care offers benefit to more than a minority of patients. However, recent clinical trials enrolling patients with MDS have reported encouraging results with use of newer drugs, including lenalidomide, decitabine, and darbepoetin alfa. Other exciting treatment regimens are being tested. Here, we present a contemporary, practical clinical approach to the diagnosis and risk-stratified treatment of MDS. We review when to suspect MDS, detail how to evaluate patients who may have a form of the condition, explain key features of treatments that are currently available in the United States, and summarize a general, common-sense therapeutic approach to patients with MDS.

Kinetics of development and characteristics of antibodies induced in cancer patients against yeast expressed rDNA derived granulocyte macrophage colony stimulating factor (GM-CSF)

We have determined the presence and kinetics of granulocyte macrophage colony stimulating factor (GM-CSF) antibodies induced after repeated administration of a yeast expressed GM-CSF product in prostate cancer patients with minimal recurrent disease using a panel of assays for detection and characterization of antibodies. Results showed that all 15 prostate cancer patients treated with GM-CSF developed GM-CSF reactive antibodies during the course of therapy. Most patients (87%) developed GM-CSF reactive antibodies within 3 months while in other patients (13%), these antibodies were induced after additional cycles of GM-CSF treatment. For most patients, the timing of occurrence of these antibodies was the same regardless of whether the ELISA or surface plasmon resonance (SPR) assays were used for detection. However, in two patients, the recognition of GM-CSF reactive antibodies by SPR assays preceded their detection by ELISA. A significant number of patients (n=9, 60%) developed GM-CSF antibodies which neutralized the biological activity of GM-CSF in vitro in a cell-line based bioassay. These antibodies also recognized GM-CSF protein from different expression systems including the non-glycosylated protein from E. coli indicating that the antibody response is directed towards the amino acid backbone of the protein. A significant effect of GM-CSF antibodies on PSA modulation was not observed in this small cohort of patients despite an alteration in PSA levels in some treated patients. The study design used here did not allow conclusions regarding the relationship between neutralizing antibodies and the PSA levels which were used as a marker for clinical outcome. Implementation of a clinical strategy which permits monitoring for antibody development and for levels of a relevant pre-determined clinical marker at appropriate time-points is necessary for assessing the impact of antibody development on the therapeutic efficacy of the protein.

Accumulation of an intron-retained mRNA for granulocyte macrophage-colony stimulating factor receptor common beta chain in neutrophils of myelodysplastic syndromes

We recently identified a reduction in the neutrophil surface expression of common beta chain (beta c) of the receptor for granulocyte macrophage-colony stimulating factor (GM-CSF) in the patients with myelodysplastic syndromes (MDS). To determine the etiology of the impaired beta c expression, beta c mRNA from neutrophilic granulocytes of MDS patients and healthy controls was analyzed by a combination of direct reverse transcriptase-polymerase chain reaction-based single-strand conformational polymorphism and sequencing. Nine different beta c transcripts were detected, but none was specific for MDS. However, one of the transcripts (beta c79) containing a 79-base intron insertion between exons V and VI was significantly increased in MDS. This 27-kd isoform consisted of the beta c N-terminal 182 amino acids followed by a new 84-amino-acid sequence. beta c79 was overexpressed in all MDS subtypes. No genomic mutations were detected within the intron or at the intron/exon boundaries. The isoform is predominantly located in the cytoplasm by Western blot analysis and was unable to generate high-affinity binding sites or transduce a signal for proliferation when coexpressed with the receptor for human GM-CSF alpha chain. Our study suggests that the accumulation of the abnormal beta c transcripts with intron V retention results in the reduction in cell-surface expression of beta c observed in MDS.

A comparative evaluation of nasal and parenteral vaccine adjuvants to elicit systemic and mucosal HIV-1 peptide-specific humoral immune responses in cynomolgus macaques

Cynomolgus macaques were immunized by either the intramuscular (i.m.) or intranasal (i.n.) route with a HIV-1 peptide-based immunogen (C4-V3 89.6P) alone, or formulated with novel adjuvants to evaluate the ability of the adjuvants to augment peptide-specific systemic and mucosal immune responses. A mutant cholera toxin, CT-E29H, or the combination of recombinant human IL-1alpha (rhIL-1alpha) protein and recombinant human GM-CSF (rhGM-CSF) protein were tested as adjuvants for i.n. immunization, while a stable emulsion of a synthetic monophosphoryl lipid A (MPL) analogue (RC529-SE) plus rhGM-CSF protein was tested as an adjuvant for i.m. immunization. Macaques immunized i.n. with peptide alone failed to elicit an anti-C4-V3 89.6P antibody response in serum. In contrast, all the tested peptide/adjuvant formulations elicited peptide-specific immune responses. RC529-SE/rhGM-CSF elicited the highest peak anti-peptide IgG geometric mean titer in serum (1:32,768 at week 25) followed by rhIL-1alpha/rhGM-CSF (1:1217 at week 10) and CT-E29H (1:256 at week 25). Measurable SHIV neutralizing antibody responses were detectable in only one macaque immunized i.m. with peptide formulated with RC529-SE/rhGM-CSF. Macaques immunized by the i.n. route with peptide in combination with CT-E29H failed to elicit measurable antibody responses at nasal or genital mucosal surfaces. In contrast, antibody responses at the nasal and genital mucosa were detected in macaques immunized by the i.n. route with peptide in combination with rhIL-1alpha/rhGM-CSF. However, antibody responses at the nasal and genital mucosa were highest in macaques immunized parenterally with peptide in combination with the adjuvants RC529-SE/rhGM-CSF. These results suggest that parenteral vaccine administration in combination with the appropriate adjuvant formulation can elicit vaccine-specific humoral immune responses in both systemic and mucosal compartments.

The myelodysplastic syndrome(s): a perspective and review highlighting current controversies

The myelodysplastic syndrome (MDS) includes a diverse group of clonal and potentially malignant bone marrow disorders characterized by ineffective and inadequate hematopoiesis. The presumed source of MDS is a genetically injured early marrow progenitor cell or pluripotential hematopoietic stem cell. The blood dyscrasias that fall under the broad diagnostic rubric of MDS appear to be quite heterogeneous, which has made it very difficult to construct a coherent, universally applicable MDS classification scheme. A recent re-classification proposal sponsored by the World Health Organization (WHO) has engendered considerable controversy. Although the precise incidence of MDS is uncertain, it has become clear that MDS is at least as common as acute myelogenous leukemia (AML). There is considerable overlap between these two conditions, and the former often segues into the latter; indeed, the distinction between AML and MDS can be murky, and some have argued that the current definitions are arbitrary. Despite the discovery of several tantalizing pathophysiological clues, the basic biology of MDS is incompletely understood. Treatment at present is generally frustrating and ineffective, and except for the small subset of patients who exhibit mild marrow dysfunction and low-risk cytogenetic lesions, the overall prognosis remains rather grim. In this narrative review, we highlight recent developments and controversies within the context of current knowledge about this mysterious and fascinating cluster of bone marrow failure states.

Late appearance of t(1;19)(q11;q11) in myelodysplastic syndrome associated with dysplastic eosinophilia and pulmonary alveolar proteinosis

We report a case of myelodysplastic syndrome (MDS), which developed marked eosinophilia and pulmonary alveolar proteinosis after the appearance of t(1;19)(q11;q11). Chromosomal analysis of the peripheral eosinophils identified the same chromosome abnormality in all metaphases to that of bone marrow blast cells. Review of the literature revealed three reported cases of concurrent MDS and pulmonary alveolar proteinosis. We reviewed four cases of concurrent MDS and pulmonary alveolar proteinosis, including the present case. Interestingly, all but one of these patients also had evidence of eosinophilia and abnormality of chromosome 1p. These findings, together with morphologic abnormalities of eosinophils observed in this case, indicate clonal involvement of eosinophils in the MDS clone, and that the eosinophilia was derived from the neoplastic clone with the translocation. We postulate that this chromosomal rearrangement is involved in the development of eosinophilia and pulmonary alveolar proteinosis in MDS.

Pentoxifylline, Ciprofloxacin and Dexamethasone Improve the Ineffective Hematopoiesis in Myelodysplastic Syndrome Patients; Malignancy

Twenty-five patients with a diagnosis of myelodysplastic syndromes (MDS) were randomized to either begin therapy with pentoxifylline, ciprofloxacin and dexamethasone (PCD) immediately (10 patients) or after a 12 week observation period (control arm, 15 patients). PCD was administered with the goal of suppressing cytokine-induced excessive intramedullary apoptosis of hematopoietic cells. No marked fluctuations of blood counts were noted during the period of observation. Twenty-two patients completed at least 12 weeks of therapy: 18/22 showed some type of hematologic response, 9/18 showing an improvement in absolute neutrophil count only (p = < 0.001) and 9/18 showing multi-lineage responses. No unique category of MDS responded better, however 19/25 patients had refractory anemia (RA)/RA with ringed sideroblasts. The median time to response was 6 weeks and 3/18 responding patients maintained their responses beyond a year. We conclude that hematologic improvement in response to PCD therapy supports the validity of this unique anti-cytokine approach. Future trials should combine PCD therapy with established approaches (growth factors/chemotherapy) and also should focus on identifying more effective ways of suppressing the pro-apoptotic cytokines in MDS.

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.

Incidence of GM-CSF antibodies in cancer patients receiving GM-CSF for immunostimulation

We have assessed the immunogenicity profile of GM-CSF in patients with either colorectal carcinoma (CRC) at different stages of disease or with multiple myeloma who were given recombinant human GM-CSF (Escherichia coli-derived) combination therapy. Metastatic CRC patients received a colon carcinoma-reactive antibody and high doses of GM-CSF (425--500 microg/day for 10 days), while other CRC patients and those with myeloma received low doses of GM-CSF (75--80 microg/day for 4 days) as an adjuvant along with appropriate tumor antigens. We found that 55% of the patients (11/20) given high doses of GM-CSF developed GM-CSF-reactive antibodies in comparison with an incidence of only 16% (4/25) in patients given low doses of GM-CSF. None of the patients developed neutralizing antibodies and so the biological effects of GM-CSF were not compromised. A majority of patients (80%) (36/45) also developed antibodies to E. coli proteins that were present as trace contaminants in the GM-CSF product. Treatment with recombinant GM-CSF products, therefore, may induce antibodies against this cytokine depending on the regimen and the amounts used. In this study, multiple immunizations with low doses of GM-CSF was associated with a low incidence of GM-CSF antibodies, which did not neutralize the effect of the cytokine. This therapeutic strategy was effective in inducing adjuvant-type effects and needs to be explored in further clinical trials with this cytokine.

Use of granulocyte colony-stimulating factor after high-dose chemotherapy and autologous peripheral blood stem cell transplantation: what is the optimal timing?

Administration of granulocyte colony-stimulating factor to patients undergoing high-dose chemotherapy and autologous peripheral blood stem cell transplantation accelerates neutrophil recovery and decreases hospitalization time. The optimal timing for granulocyte colony-stimulating factor infusion remains unknown. In this retrospective, case-controlled, two-armed study, we reviewed our experience at Hahnemann University Hospital to determine whether initiating granulocyte colony-stimulating factor infusions on posttransplant day 0 versus day 8 affects neutrophil recovery time, posttransplant discharge date, total hospital days after high-dose chemotherapy, and autologous peripheral blood stem cell transplantation. All patients hospitalized between 1994 and 1998 at Hahnemann University Hospital, Bone Marrow Transplantation Unit with breast cancer or non-Hodgkin's lymphoma, who underwent high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation and received granulocyte colony-stimulating factor either on posttransplant day 0 (16 patients) or day 8 (16 patients). The day 0 and day 8 groups had no statistically significant differences in age, sex, weight, height, body surface area, disease characteristics, pretransplant harvesting or conditioning regimens, or transplant CD34+ cell counts. Our main outcome measure was the mean time to reach absolute neutrophil count greater than or equal to 0.5 x 10(9)/l, the number of hospital days after transplant, and the total hospital days. The mean days to neutrophil recovery (10.56 versus 9.68, p = 0.48), posttransplant hospital days (13.62 versus 12.81, p = 0.39), and total hospital days (20.25 versus 20.25, p = 1.00) were not significantly different between day 8 and day 0 groups, respectively. No significant effects on neutrophil recovery time, posttransplant hospital days, or total hospital days were observed with the initial granulocyte colony-stimulating factor infusion on day 0 versus day 8 after transplant. Delayed administration may allow substantial cost savings (US$200 x 8 approximately equal to US $1,600 per patient) without affecting clinical outcome. More studies are needed to determine whether greater delay is feasible.

Effect of recombinant human erythropoietin combined with granulocyte/ macrophage colony-stimulating factor in the treatment of patients with myelodysplastic syndrome

This randomized, placebo-controlled trial was designed to assess the efficacy and safety of therapy with granulocyte-macrophage colony-stimulating factor (GM-CSF) and erythropoietin (epoetin alfa) in anemic, neutropenic patients with myelodysplastic syndrome. Sixty-six patients were enrolled according to the following French–American–British classification: refractory anemia (20), refractory anemia with excess blasts (35), refractory anemia with ringed sideroblasts (9), and refractory anemia with excess blasts in transformation (2). Patients were stratified by their serum erythropoietin levels (less than or equal to 500 mU/mL, n = 37; greater than 500 mU/mL, n = 29) and randomized, in a 2:1 ratio, to either GM-CSF (0.3-5.0 μg/kg·d) + epoetin alfa (150 IU/kg 3 times/wk) or GM-CSF (0.3-5.0 μg/kg·d) + placebo (3 times/wk). The mean neutrophil count rose from 948 to 3831 during treatment with GM-CSF ± epoetin alfa. Hemoglobin response (increase greater than or equal to 2 g/dL, unrelated to transfusion) occurred in 4 of 45 (9%) patients in the GM-CSF + epoetin alfa group compared with 1 of 21 (5%) patients with GM-CSF + placebo group (P = NS). Percentages of patients in the epoetin alfa and the placebo groups requiring transfusions of red blood cells were 60% and 92%, respectively, for the low-endogenous erythropoietin patients and 95% and 89% for the high-endogenous erythropoietin patients (P = NS). Similarly, the average numbers of units of red blood cells transfused during the 12-week study in the epoetin alfa and the placebo groups were 5.9 and 9.5, respectively, in the low-endogenous erythropoietin patients and 9.7 and 8.6 in the high-endogenous erythropoietin patients (P = NS). GM-CSF ± epoetin alfa had no effect on mean platelet count. Treatment was well tolerated in most patients, though 10 withdrew from the study for reasons related predominantly to GM-CSF toxicity.

Immunization With Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor as a Vaccine Adjuvant Elicits Both a Cellular and Humoral Response to Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine for the generation and propagation of antigen-presenting cells and for priming a cellular immune response. We report here that use of recombinant human GM-CSF (rhGM-CSF), administered as an adjuvant in a peptide-based vaccine trial given monthly by intradermal injection, led to the development of a T-cell and antibody response to rhGM-CSF. An antibody response occurred in the majority of patients (72%). This antibody response was not found to be neutralizing. In addition, by 48-hour delayed type hypersensitivity (DTH) skin testing, 17% of patients were shown to have a cellular immune response to the adjuvant rhGM-CSF alone. Thymidine incorporation assays also showed a peripheral blood T-cell response to rhGM-CSF in at least 17% of the patients. The generation of rhGM-CSF–specific T-cell immune responses, elicited in this fashion, is an important observation because rhGM-CSF is being used as a vaccine adjuvant in various vaccine strategies. rhGM-CSF–specific immune responses may be incorrectly interpreted as antigen-specific immunity, particularly when local DTH responses to vaccination are the primary means of immunologic evaluation. We found no evidence of hematologic or infectious complications as a result of the development of rhGM-CSF–specific immune responses.

Immunization With Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor as a Vaccine Adjuvant Elicits Both a Cellular and Humoral Response to Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine for the generation and propagation of antigen-presenting cells and for priming a cellular immune response. We report here that use of recombinant human GM-CSF (rhGM-CSF), administered as an adjuvant in a peptide-based vaccine trial given monthly by intradermal injection, led to the development of a T-cell and antibody response to rhGM-CSF. An antibody response occurred in the majority of patients (72%). This antibody response was not found to be neutralizing. In addition, by 48-hour delayed type hypersensitivity (DTH) skin testing, 17% of patients were shown to have a cellular immune response to the adjuvant rhGM-CSF alone. Thymidine incorporation assays also showed a peripheral blood T-cell response to rhGM-CSF in at least 17% of the patients. The generation of rhGM-CSF–specific T-cell immune responses, elicited in this fashion, is an important observation because rhGM-CSF is being used as a vaccine adjuvant in various vaccine strategies. rhGM-CSF–specific immune responses may be incorrectly interpreted as antigen-specific immunity, particularly when local DTH responses to vaccination are the primary means of immunologic evaluation. We found no evidence of hematologic or infectious complications as a result of the development of rhGM-CSF–specific immune responses.

Thrombopoietic factors potentially useful in the treatment of acute leukemia

Thrombocytopenia is a major cause of morbidity following intensive chemotherapy for acute leukemia. Over recent years, there has been an increasing use of platelet transfusions which, although generally efficacious to prevent severe hemorrhage, have associated risks of transmitting blood-borne disease and of alloimmunization. Therefore, there is a clinical requirement for a drug that will reliably alleviate the thrombocytopenia associated with leukemia therapy. The c-mpl ligand thrombopoietin is the most interesting factor for the treatment of thrombocytopenia because of its lineage specificity. Phase I and II studies confirm its biological efficacy to induce rise in platelet count in patients with solid tumors and acute leukemia. Several other pleiotropic hematopoietic growth factors are also currently in clinical trials. These include interleukin-6, interleukin-3, interleukin-11, PIXY321 and stem cell factor. The effects of these cytokines appear to be modest at most and, with the exception of interleukin-11, their side effects are likely to limit their clinical application. Combinations of factors may prove more efficacious approaches to enhance platelet recovery.

Growth characteristics of myelodysplastic CD34+ cells

Myelodysplastic syndromes (MDS) are a heterogeneous group of disorders of hematopoiesis entailing hyperproliferative and ineffective hematopoiesis associated with morphologic evidence of marrow cell dysplasia resulting in refractory cytopenia(s), and an increased risk of transformation into acute myeloblastic leukemia (AML). The administration of colony-stimulating factor(s) (CSFs) to patients with MDS increased blood neutrophil concentrations, in most patients, and it was anticipated to be of benefit to prevent infections. The progression to AML while being treated with CSFs has come under close scrutiny. In vitro studies are expected to produce more pertinent criteria for selection of patients who are likely to benefit, as well as the overall benefits of various therapies. For this purpose, in vitro colony assays are an excellent approach for investigation of the biologic characteristics of MDS progenitor cells. The stem cell phenotype CD34 is the one of the best markers of progenitor cells, and can be used for the purification of these cells to unify levels of maturation; a direct comparison of proliferative and differentiative capacity of MDS progenitor cells with normal CD34+ cells can thus be made. The properties of MDS CD34+ cells are described here in association with proliferation and differentiation, with special emphasis on the role of stem cell factor (a ligand for c-kit) in leukemic type growth of MDS CD34+ cells.

Hematopoietic growth factors for the treatment of myelodysplastic syndromes

Administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF), rh granulocyte-macrophage colony-stimulating factor (rhGM-CSF) or rh interleukin-3 (rhIL-3) effectively stimulate and expand marrow myelopoiesis resulting in a dose-dependent increment of peripheral blood neutrophils in most patients with myelodysplasias (MDS). Clinical outcome with fewer infections have been reported in a few studies using rhG-CSF or rhGM-CSF, including a large randomized, controlled trial with rhGM-CSF. Clinical effective stimulation of megakaryopoiesis and erythropoiesis are however infrequent. Recently, rh erythropoietin (rhEpo) has been used to overcome the ineffective erythropoiesis in MDS to reduce transfusions needed. However, the efficiency has been low in most studies with marked differences in response rates. The most impressive clinical results were obtained in patients with milder forms of MDS combined with low prestudy endogenous S-Epo levels. The possible synergistic effect of combining rhEpo with rhG-CSF or rhGM-CSF has been studied with erythropoietic response rates of about 40%. The safety of the cytokine administration seems acceptable with no significant stimulation of leukemic myelopoiesis and subsequent progression into overt acute myeloid leukemia. In conclusion, combinations of hematopoietic growth factors may be of clinical benefit in some patients with MDS. However, due to the cost and unpredictable clinical outcome there is a need for extended laboratory research to understand the functional defects of MDS stem cells and progenitors.

Clinical use of hematopoietic growth factors in the myelodysplastic syndromes

Recent advances in the molecular genetics of myelodysplastic syndromes (MDS) have shed new light on the pathogenesis of MDS allowing a better understanding of the defects of differentiation of the transformed clone and suppression of normal hematopoiesis. The clinical hematologist, however, continues to be challenged with the treatment of patients with MDS. Pancytopenia and defective function of neutrophils and platelets lead to a high risk of infectious and hemorrhagic complications. The progression to acute myeloid leukemia adds to morbidity and mortality. Supportive care including red blood cell and platelet transfusions are still the cornerstone of therapeutic management. While prophylactic administration of G-CSF or GM-CSF cannot be recommended, treatment of febrile neutropenia might benefit from administration of G-CSF in addition to antibiotics. Administration of high-dose erythropoietin will improve erythropoiesis in around 20% of the patients, mainly in those with rather preserved erythroid function and no or low transfusion need. Coadministration of erythropoietin with either G-CSF or GM-CSF could increase the response rate. Allogeneic stem cell transplantation still is the only curative treatment and prolongs survival. Intensive chemotherapy for advanced MDS is possible with an acceptably low rate of early death and a complete remission rate between 45% to 60%, while initial results of autologous transplantation are promising.

Anti-cytokine autoantibodies: epiphenomenon or critical modulators of cytokine action

Low amounts of high-affinity autoantibodies to various cytokines have been detected in sera from healthy donors. Their levels, although highly variable, are increased in the circulation of patients subjected to cytokine therapy or suffering from a variety of immunoinflammatory diseases. It has been suggested that these autoantibodies play a regulatory role in the intensity and duration of an immune response. The antibodies may prevent the binding of a cytokine to its specific cell surface receptor thereby neutralizing its biological activity in vivo. They may also act as carrier proteins preventing the rapid elimination of a cytokine from the circulation and thus increase its bioactivity. Additionally or alternatively, autoantibodies may modulate cytokine-induced intracellular signal transduction pathways or trigger complement-mediated cytotoxicity towards cells carrying membrane-bound cytokines. The autoantibodies may exert their regulatory role in compliance with the other factors that control cytokine activity, including soluble cytokine receptors, cell surface decoy receptors, and receptor antagonists. Although not favored by many investigators, a less sophisticated role for naturally occurring anti-cytokine autoantibodies should be considered as well. Recent evidence has shown that autoantibodies are generated at a high frequency as part of a response to foreign antigens. These antibodies are produced by B cells arising from the process of somatic mutation. Thus anti-cytokine autoantibodies may be the result of a "leaky" B cell response triggered by immunoinflammatory processes. High-titered autoantibodies induced by cytokine therapy are of clinical concern since their occurrence is often associated with the loss of response to treatment. Moreover, they may also neutralize endogenously produced cytokines with possible pathological consequences. In this paper we have reviewed the available information on the biological and clinical significance of both naturally occurring and therapeutically induced anti-cytokine autoantibodies in animals and man with the emphasis on antibodies directed to interferons.

Pharmacokinetics of recombinant human granulocyte-macrophage colony-stimulating factor: the effects of zidovudine

Recombinant human granulocyte-macrophage colony-stimulating factor (rHu GM-CSF) enhances bone marrow production of and stimulates granulocytes, macrophages, and eosinophils. Granulocyte-macrophage colony-stimulating factor may be used concomitantly with zidovudine in human immunodeficiency virus (HIV)-positive patients to minimize zidovudine-associated neutropenia. This open-label, randomized, placebo-controlled study was performed to evaluate the pharmacokinetic disposition of rHu GM-CSF in HIV-positive, asymptomatic patients in the absence and presence of concomitant zidovudine administration. Eight participants received rHu GM-CSF (5 micrograms/kg subcutaneously) daily for 4 days in combination with placebo or zidovudine (200 mg orally every 8 hours) in a randomized, crossover fashion, with each study period separated by a 3-day washout phase. Pharmacokinetic blood sampling was performed over 16 hours on days 1 and 4 of both treatment periods, and subsequent analysis of serum was performed using an enzyme-linked immunosorbent assay. Pharmacokinetic results of rHu GM-CSF at steady state (days 4 of periods I and II) in the absence (placebo) and presence of zidovudine included apparent total body clearance, half-life, and apparent volume of distribution, all of which were not significantly altered with concomitant administration of zidovudine. Mean pharmacokinetic results of rHu GM-CSF after the first dose (days 1 of periods I and II) were similar to steady-state values; however, total body clearance was significantly increased at steady state compared with the results of the first dose. Concurrent administration of zidovudine does not influence the pharmacokinetic disposition of rHu GM-CSF after single or multiple doses.

Neutralising antibodies to granulocyte-macrophage colony stimulating factor (GM-CSF) in carcinoma patients following GM-CSF combination therapy

There is a high risk of developing neutralizing and non-neutralizing antibodies when GM-CSF is used as an immunomodulatory agent in non-immune compromised patients and not in combination with chemotherapy. The presence of neutralizing antibodies may seriously hamper the clinical response of the patients this must be taken into account when designing protocols if the biological activity of the exogenously administered GM-CSF is not to be impaired and the endogenous production of GM-CSF is not to be inactivated. Assessment of production of neutralising antibodies during cytokine therapy is important for predicting the clinical response to progressive therapy.

Clinical use of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor in neutropenia associated with malignancy

G-CSF and GM-CSF have been shown in each clinical setting to reduce the duration of neutropenia, with the exception of the scant data available in the unrelated bone marrow transplant setting. These growth factors also have been shown to have no leukemogenic effect during the observation periods of the trials discussed. In MDS, one major randomized trial has demonstrated a reduction in incidence of infection. This has not yet been demonstrated in AML and allogeneic BMT. Data from ongoing and future trials will be helpful in elucidating their effect on treatment-related morbidity and overall survival.

Proliferation and differentiation of myelodysplastic CD34+ cells

Myelodysplastic syndromes (MDS) are a heterogeneous group of disorders of hematopoiesis involving hyperproliferative and ineffective hematopoiesis associated with morphologic evidence of marrow cell dysplasia resulting in refractory cytopenia(s), and an increased risk of transformation into acute myeloblastic leukemia (AML). The administration of colony-stimulating factor(s) (CSFs) to patients with MDS increased blood neutrophil concentrations, in most patients, and was also expected to be beneficial and to prevent infections. However, the progression to AML during the treatment with CSFs was suspected in some patients. Therefore, extensive in vitro studies were expected to lead to the establishment of criteria for selection of patients who are likely to benefit from CSF's as well as to establish the overall value of the different types of CSFs therapy. For this purpose, in vitro colony assays provide an excellent tool for investigating the biologic characteristics of MDS progenitor cells. However, conditions of the culture must be such that each progenitor can express its full potential for proliferation and differentiation. Because of the above, MDS progenitor cells cannot be used because they carry an impairment in proliferation and differentiation. To address this problem, one needs to know how many cells are being handled and the maximum numbers of colonies and clusters expected. CD34, a stem cell phenotype, is at present one of the best markers of progenitor cells, and can be used for purposes of purification. Using a defined number of CD34+ cells, it was feasible to make direct investigations on MDS progenitor cells. In this review the properties of MDS progenitor cells are described, in association with proliferation and differentiation, with special emphasis on the phenotypic subpopulations of MDS CD34+ cells.

Immediate hypersensitivity to human recombinant granulocyte-macrophage colony-stimulating factor associated with a positive prick skin test reaction

BACKGROUND

Recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF), also known as sargramostim, is used to accelerate myeloid recovery following bone marrow transplantation or cytotoxic chemotherapy. "Anaphylactic" reactions to sargramostim have been reported on a limited basis and are poorly characterized.

OBJECTIVE

It is the purpose of this report to describe an adverse reaction to sargramostim treatment involving palmar itching, urticaria, angioedema, and throat tightness and to demonstrate the utility of prick skin testing to determine type I sensitization.

METHODS

Prick skin testing with 100 and 250 micrograms/mL sargramostim and 300 micrograms/mL rhu G-CSF (filgrastim) was performed in the patient and four control subjects.

RESULTS

The patient experienced an immediate wheal and flare reaction with both concentrations of sargramostim while the control subjects demonstrated no reaction. There was also no reaction with filgrastim (rhu G-CSF) in either group and the patient subsequently tolerated filgrastim therapy.

CONCLUSION

Prick skin testing with rhu GM-CSF and rhu G-CSF may be useful to demonstrate type I sensitization. Additional studies are needed to determine the incidence and prevalence of skin test reactions in larger numbers of patients with cytokine therapy exposure.

The thrombocytopenia of cancer. Prospects for effective cytokine therapy

The previous 10 years have witnessed the development of increasing needs for platelet transfusion in support of aggressive therapies of malignancy. Despite gains in our understanding of platelet preparation, storage, and transfusion, alternative therapies are clearly desirable. During the late 1980s at least six distinct cytokines that display effects on megakaryocyte growth and differentiation-IL-3, KL, GM-CSF, IL-6, IL-11, and LIF- and a synthetic growth factor, PIXY 321, were cloned and characterized. Although none of these cytokines fulfill all of the physiologic roles of thrombopoietin, in its absence several have undergone extensive preclinical and preliminary clinical testing. Of these, IL-11 and PIXY 321 hold promise for clinical amelioration of thrombocytopenia in cancer patients. With the recent cloning of thrombopoietin and its promise in preclinical trials, the role of each of these recombinant proteins in clinical medicine is undergoing careful evaluation. As with erythropoietin and G-CSF before it, given its normal role in the regulation of platelet production, Tpo would appear to provide the greatest physiologic stimulus to platelet production in states of natural and iatrogenic marrow failure. Careful clinical trials of the agent are needed to determine whether the hormone will fulfill this promise. The following decade will most certainly see the resolution of many of the complications of thrombocytopenia and its transfusional support.

Myelodysplastic syndromes in the elderly: the role of growth factors in management

Myelodysplastic syndrome (MDS) comprises a group of heterogeneous clonal bone marrow disorders leading to peripheral cytopenia(s) and hypercellular marrow in the majority of the patients. The morphology of the cell lines is characterized by dysplastic features in some or all cell lines. The FAB classification has divided MDS in five subgroups, namely (1) RA (refractory anemia); (2) RARS (refractory anemia with ring sideroblasts); (3) CMML (chronic myelomonocytic leukemia); (4) RAEB (refractory anemia with excess blasts); and (5) RAEB-T (refractory anemia with excess blasts in transformation). Myelodysplastic syndrome remains primarily a disease of the elderly. With a reported median age of 74.4 years, patients have a chronic relentless course with complication of cytopenias, and a significant number of MDS patients, especially from the RAEB and RAEB-T categories, end up in acute myeloid leukemic transformation. Cytogenetic abnormalities are present in 40-58% of the cases and can provide not only help in diagnosis, but also understanding regarding the clinical course and prognostic aspect. Management of MDS is quite pragmatic and at this stage far from satisfactory. Various modalities have included use of differentiating agents, aggressive chemotherapy, bone marrow transplant and, more recently, significant interest has been generated in the use of hematopoietic growth factors. Differentiating agent trials have been unrewarding so far; chemotherapy trials have resulted in less benefit and more early toxic deaths, especially in the elderly MDS patients where the disease predominates. Bone marrow transplant appears suitable for some patients who are at a younger age. Salvation from this disease is being searched in the proper usage of hematopoietic growth factors and cytokines. There has been concern, however, that usage of growth factors has led to early and enhanced transformation of these patients to frank acute leukemic states. This concept appears to be somewhat refuted by newer controlled trials with GM-CSF and G-CSF, emphasizing that the acute leukemic transformation is the natural course of the disease and is not hastened by growth factor use. Preliminary studies are also suggesting that a combination of growth factors, especially G-CSF and erythropoietin as compared to chemotherapies, could be more beneficial in prolonging the survival of MDS patients who have progressed to the acute leukemic phase. More studies are needed for the understanding of the pathogenetic mechanism(s) in order to facilitate a more suitable and appropriate management strategy for MDS.

Chemotherapy combined with zidovudine and GM-CSF in human immunodeficiency virus-related non-Hodgkin's lymphoma

OBJECTIVE

The treatment of patients with non-Hodgkin's lymphoma related to the human immunodeficiency virus (HIV-NHL) is complicated by the underlying acquired immunodeficiency syndrome (AIDS). Patients without adverse prognostic factors (no AIDS prior to lymphoma, CD4+ lymphocyte counts greater than 100 x 10(6)/l and good performance status) can be cured of lymphoma and experience long-term survival. Our previous study with the intensive chemotherapy LNH84 regimen yielded a 63% complete response (CR) rate but median survival was only nine months, half of the patients died of AIDS and the other half of their lymphoma. We report here the results of a phase II study combining the same chemotherapy with zidovudine and GM-CSF. Our goal was to improve the treatment outcome over that of our previous study; GM-CSF was expected to decrease the hematological toxicity of chemotherapy and thus permit a dose intensity increase, while zidovudine was supposed to slow down the evolution of AIDS.

DESIGN AND SETTING

A phase II non-randomized prospective clinical trial in 7 centres.

PATIENTS AND METHODS

Thirty-two consecutive adult patients presenting HIV-NHL and performance status of less than three without active opportunistic infection underwent three cycles of doxorubicin 75 mg/m2, cyclophosphamide 1,200 mg/m2, vindesine 2 mg/m2 for two days, bleomycin 10 mg for two days and prednisolone 60 mg/m2 for five days (ACVB). Chemotherapy was associated with zidovudine (5 mg/kg/d) and GM-CSF (5 mu g/kg/d). The induction phase was followed by a four-month consolidation phase.

RESULTS

CR and PR > 75% were observed in 56% of patients; 25% of the patients died during the induction phase. These results were analogous to those of the previous study (63% and 14%, respectively). Neither hematological tolerance nor dose intensity were improved. With a mean follow-up of 23.5 months, median survival was 6.7 months. The rate of non-NHL AIDS-related death during CR was not reduced (22% in our study vs. 16% in our previous one).

CONCLUSIONS

GM-CSF failed to reduce significantly the cumulative hematological toxicity of chemotherapy and zidovudine. New antiviral agents without hematological toxicity would perhaps be useful in this setting.

Increased proliferation of eosinophil clusters in myelodysplastic syndromes

A patient with myelodysplastic syndromes (MDS) developed eosinophilia during treatment with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF). To study the mechanism of this eosinophilia, we investigated the proliferation of eosinophil colony-forming units (CFU-Eo) in nine patients and four healthy controls. Eosinophil clusters increased significantly in the patients (P < 0.01) compared with controls, but eosinophil colonies were not different between controls and MDS patients. In addition, the eosinophil clusters were significantly increased with rhGM-CSF in MDS patients compared with controls, although serum GM-CSF concentrations were similar in both groups. These results suggest that eosinophil clusters are increased in MDS either through abnormal progenitor proliferation or hypersensitivity to GM-CSF.

Granulocyte colony-stimulating factor in acute myeloid leukemia

The clinical application of recombinant human G-CSF in patients with acute myeloid leukemia (AML) has been controversial because it stimulates the in vitro proliferation of leukemic cells. In order to explore the possibility of predicting in vivo leukemic proliferation after G-CSF administration to AML patients by using in vitro assays, we investigated the leukemic blasts of 30 AML patients, including 14 patients who received G-CSF for severe infection associated with neutropenia following chemotherapy (G-CSF group) and 16 patients who did not (control group). Of the 14 patients in the G-CSF group, 9 showed an increase of leukemic blasts in the peripheral blood during G-CSF administration, while 11 of the 16 control patients developed leukemic resurgence. In the G-CSF group, the frequency of leukemic resurgence among patients whose blasts showed dose-dependent proliferation after addition of G-CSF to cultures was similar to that among patients whose blasts did not. In addition, there were no significant differences between the G-CSF and control groups in [3H]thymidine incorporation by leukemic cells and leukemic colony formation after the addition of G-CSF to cultures. The G-CSF receptor affinity of leukemic blasts was significantly higher in the patients with leukemic resurgence (mean dissociation constant [Kd]: 55 pM in the G-CSF group and 63 pM in the control group) than in those without it (101 pM and 96 pM, respectively), and the number of G-CSF receptors per cell was significantly lower when leukemic resurgence occurred (200 in the G-CSF group and 260 in the control group) than when it did not (3400 and 3030, respectively). Immunophenotyping (for CD2, CD7, CD10, CD13, CD19, CD33, CD34, CD71, HLA-DR, glycophorin A and the G-CSF receptor) revealed no significant differences between blasts from the patients with and without leukemic resurgence in the G-CSF group. Thus, we conclude that the in vivo leukemic resurgence during G-CSF administration after chemotherapy for AML was not correlated with the in vitro responsiveness of leukemic blasts to this cytokine or with blast phenotyping data. Leukemic resurgence is likely to occur in patients whose leukemic blasts have fewer numbers of G-CSF receptors with a high affinity irrespective of whether patients receive G-CSF.

All-trans retinoic acid in the treatment of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of hematopoietic disorders characterized by uni- or multilineage maturation defects of the bone marrow. Controversial therapeutic results have been obtained using growth factors or differentiating agents such as 13-cis retinoic acid. In this pilot study we evaluated the effects of all-trans retinoic acid (ATRA) in 10 MDS patients (5 male, 5 female). Six patients had refractory anemia (RA), 1 had refractory anemia with excess of blasts (RAEB), and 3 had refractory anemia with excess of blasts in transformation (RAEB-t). All patients received the same dose of ATRA (45 mg/sqm/day) orally for 6 weeks. A rise in hemoglobin concentration > 1g/dl was observed in 3/10 patients, while 5/10 patients showed an increase in granulocyte count > 0.5 x 10(9)/l without concomitant increase in the percentage of blast cells in the bone marrow. A rise in the platelet count > 50 x 10(9)/l was observed in 1/10 patients. All the effects were transient and maximal responses were obtained by the fourth week of treatment. Thereafter, the peripheral blood counts started to drop again, reaching pre-therapy values by the end of the treatment. This phenomenon could be attributed either to the exhaustion of an ATRA-responding cell pool, the development of cellular resistance to ATRA or to a reduction of plasma ATRA levels after prolonged treatment. According to our results, it seems that ATRA might have therapeutic efficacy in MDS, particularly if its effect could be improved by combinations with other differentiating agents or growth factors.

G-CSF in the biology and treatment of acute myeloid leukemias

Granulocyte colony-stimulating factor (G-CSF) is an hemopoietic growth factor produced by fibroblasts, monocytes and endothelial cells. The role of G-CSF in the biology of acute myeloid leukemia (AML) has been investigated by several authors, who have demonstrated receptor mediated enhanced proliferation of AML blasts in vitro, in the presence of G-CSF. This effect is further increased by addition of other cytokines such as GM-CSF, IL3, IL4, Stem cell factor (SCF), while Tumor Necrosis Factor (TNF) and Transforming Growth Factor beta 1 (TGF beta 1) seem to exert an inhibitory activity. An autocrine production of G-CSF by AML cells, a paracrine production by accessory cells and a protective effect displayed by G-CSF against programmed cell death could partially contribute to explain the pathogenesis of AML. In vivo, G-CSF has been used after chemotherapy in AML, in order to improve hemopoietic recovery in patients at high risk of infection. Current studies are focusing on better definition of the role of G-CSF, as such or combined with other biological modifiers, in dose intensification and autologous bone marrow or peripheral blood stem cell transplantation.

Effects of long-term treatment with recombinant human granulocyte-macrophage colony-stimulating factor in patients with myelodysplastic syndrome

We examined the effects of long-term treatment with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) in 61 patients with myelodysplastic syndrome (MDS). Patients were randomly assigned to receive daily subcutaneous injection of 60 micrograms/m2, 125 micrograms/m2 or 250 micrograms/m2 for 8 weeks. A significant increase in granulocyte counts including neutrophils and eosinophils was shown from one week after the start of the treatment in all three dose groups. The increase in granulocyte counts reached a plateau at the 4th week and was sustained during the treatment period. However, no consistent change in other cell lineages including monocytes, lymphocytes, reticulocytes and platelets were observed. Nevertheless peak-levels of these cells were significantly higher than the pre-treatment levels. In higher dose groups, the number of patients developing infections was reduced. There was no significant difference in the incidence of adverse events among the 3 dose groups, and the toxicity was generally well-tolerated. These observations indicate that treatment with rhGM-CSF can be of potential therapeutic benefit to patients with MDS.

Pharmacokinetics of recombinant human granulocyte-macrophage colony-stimulating factor in children after intravenous and subcutaneous administration

Despite its widespread use, only limited pharmacokinetic data exist for recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), especially in children. We evaluated the pharmacokinetics of rhGM-CSF in children who had undergone intensive multiagent chemotherapy: 11 children with refractory solid tumors received 500-1500 micrograms/m2 of rhGM-CSF (sargramostim) as a daily 2-h intravenous (iv) infusion, and seven children received subcutaneous (sc) rhGM-CSF at 1500-2000 micrograms/m2/d in two daily injections for 2 weeks. Serum samples obtained before and after rhGM-CSF administration were analyzed for granulocyte-macrophage colony-stimulating factor (GM-CSF) by a bioassay and by ELISA. Concentrations measured by the two methods were highly correlated (r2 = 0.89, p < 0.001). Following 2-h iv infusions, the concentration-time data were best described by a two-compartment, first-order elimination model. The median (range) for rhGM-CSF systemic clearance (CI) was 49 mL/min/m2 (range, 15-118 mL/min/m2), terminal half-life (t1/2) was 1.6 h (range, 0.9-2.5 h), and the time the GM-CSF concentration was > 1 ng/mL was 9 h (range, 6-13 h). The CI was not dose dependent or related to patient age. The absolute neutrophil count day 14 of GM-CSF was significantly related to GM-CSF dosage and platelet count on day 1. There was a weak correlation between AUC and duration of neutropenia (p = 0.05). The sc concentration-time data were best described by a one-compartment model with first-order absorption and elimination. Median apparent clearance was 72 mL/min/m2 (range, 27-231 mL/min/m2) and t1/2 was 2.3 h (range 0.7-3.8 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Proliferation and differentiation of myelodysplastic CD34+ cells in serum-free medium: II. Response to combined colony-stimulating factors

To investigate the role of colony stimulating factors (CSFs) in the proliferation and differentiation of progenitor cells from myelodysplastic syndromes (MDS), marrow progenitor cells from 18 MDS patients were highly purified using CD34 monoclonal antibody and immunomagnetic microspheres (MDS CD34+ cells). These cells were cultured in serum-free medium with various combinations of five colony stimulating factors (CSFs): recombinant human interleukin-3 (rIL-3), granulocyte/macrophage-CSF (rGM-CSF), granulocyte-CSF (rG-CSF), macrophage-CSF (rM-CSF), and erythropoietin (rEP). Among the tested CSFs, such as rM-CSF, rG-CSF, rGM-CSF and rIL-3, a combination of the first three CSFs was the most effective stimulus for the proliferation of non-erythroid MDS progenitor cells. An increase of undifferentiated "blast" cell colonies in 5/18 MDS patients occurred and these 5 patients belonged to the high-risk group. In the presence of these three CSFs, rIL-3 had no effect on the proliferation and differentiation of MDS CD34+ cells; however, IL-3 was efficient for the proliferation of MDS CD34+ cells to the erythroid lineage. rGM-CSF or rIL-3 alone did not efficiently support proliferation and differentiation of CD34+ cells. M-CSF is present in normal human serum at a concentration of 550 +/- 110 U/ml, a concentration exceeding that used in this study (100 U/ml). Therefore, in vivo administration of G-CSF combined with GM-CSF to MDS patients may be one of the most effective CSF combinations for proliferation of MDS progenitor cells to the non-erythroid lineage. However, the effect on the capacity for differentiation was minimal, especially in patients belonging to the high-risk group.

Hemopoietic growth and inhibitory factors in treatment of malignancies. A review

The clinical use of cytokines is still expanding as the knowledge of beneficial effects as adjunct to cancer treatment is increasing. G-CSF and GM-CSF stimulates hemopoietic recovery after myelosuppressive chemotherapy and enhances engraftment after bone marrow transplantation. New cytokines as IL-1, IL-3, IL-4 and IL-6, are studied in clinical trials and combinations of these with stem cell factor seem promising in ex vivo expansion of stem cells. GM-CSF also have antitumor effects. The most recently discovered hemopoietic growth factor is thrombopoietin, from which probably especially patients with leukemia will benefit.