Short- and long-term benefits of lenalidomide treatment in patients with lower-risk del(5q) myelodysplastic syndromes.

The treatment of patients with myelodysplastic syndromes (MDS) begins with assessment of karyotype and risk. Lenalidomide is approved for the treatment of patients who have transfusion-dependent anemia due to lower-risk MDS with chromosome 5q deletion (del(5q)) with or without additional cytogenetic abnormalities, and isolated del(5q) only in the European Union. Mounting evidence suggests that lenalidomide is effective not only in reducing red blood cell (RBC) transfusion burden, but also in modifying the disease natural history by suppressing the malignant clone. Data discussed here from the pivotal phase 2 (MDS-003) and phase 3 (MDS-004) studies of lenalidomide demonstrate that lenalidomide treatment was associated with both short- and long-term benefits. These clinical benefits included high rates of RBC-transfusion independence (TI) with prolonged durations of response, high rates of cytogenetic response (CyR) associated with achievement of durable RBC-TI, no significant difference in rates of progression to acute myeloid leukemia (AML), and improvements in health-related quality of life (HRQOL). Achievement of RBC-TI and CyR with lenalidomide treatment was associated with extended survival and time to AML progression. Achievement of RBC-TI and hemoglobin response was additionally associated with HRQOL benefits. Recent data describing the impact of TP53 mutations and p53 expression on the prognosis of patients with del(5q) and the impact on response to lenalidomide are also discussed. The authors provide practical recommendations for the use of lenalidomide in patients with lower-risk del(5q) MDS.

Deletion of IRF-1, mapping to chromosome 5q31.1, in human leukemia and preleukemic myelodysplasia.

One of the most frequent cytogenetic abnormalities in human leukemia and myelodysplasia is an interstitial deletion within chromosome 5q. A tumor suppressor gene has been hypothesized to lie in 5q31, the smallest commonly deleted region. IRF-1, a gene whose product manifests anti-oncogenic activity, was mapped to 5q31.1. IRF-1 lies between IL-5 and CDC25C and is centromeric to IL-3 and GM-CSF. Among these genes, only IRF-1 was consistently deleted at one or both alleles in 13 cases of leukemia or myelodysplasia with aberrations of 5q31. Inactivating rearrangements of one IRF-1 allele, accompanied by deletion of the second allele, were also identified in one case of acute leukemia. Thus, IRF-1 may be a critically deleted gene in human leukemia and myelodysplasia.

Prevalence and clinical association of clonal T-cell expansions in Myelodysplastic Syndrome.

Selected patients with Myelodysplastic Syndromes (MDS) are responsive to immunosuppressive therapy, suggesting that hematopoietic suppressive T cells have a pathogenic role in ineffective hematopoiesis. We assessed T-cell receptor (TCR) clonality through combined flow cytometry and molecular analysis of the complementarity determining region (CDR)-3 of the T-cell receptor-Vbeta gene. We identified clonal T cells in 50% of MDS patients (n=52) compared to 5% of age-matched normal controls (n=20). The presence of T-cell clones was not associated with features linked previously to immunosuppression response, including WHO diagnostic category, karyotype, marrow cellularity, IPSS category, sex or age

Intrapatient functional clonality deconvoluted by coupling intracellular flow cytometry and next-generation sequencing in human leukemia.

The interplay between tumor heterogeneity and microenvironmental factors is a critical mechanism for clonal selection in leukemia. Evidence of unique clonal capacities to engraft within patient-derived xenograft (PDX) models suggests that intrapatient genetic architecture may be defined by functional differences at the clonal level. However, methods to detect functional differences assigned to genetically defined clones remain limited. Here, we describe a scalable method to directly measure the functional properties of clones within the same leukemia patient by coupling intracellular flow cytometry and next-generation sequencing (NGS). We provide proof of concept utilizing primary chronic myelmonocytic leukemia (CMML) samples and granulocyte-macrophage colony stimulating factor (GM-CSF) to elucidate the interaction between tumor heterogeneity and microenvironmental factors. Mixtures of human leukemia cell lines, with known response to GM-CSF, were used to validate the accuracy of our methodology. Using this approach, we confirm that our method is capable of discriminating GM-CSF sensitive cell lines, identifies somatic variants in primary leukemia samples, and resolves functional clonal architecture in an illustrative patient. Taken together, our data describes a novel method to determine intrapatient functional clonal heterogeneity and provides proof-of-concept for future investigation aimed at elucidating the clinical relevance of functional clonal differences.

Phase 1 study of PTK787/ZK 222584, a small molecule tyrosine kinase receptor inhibitor, for the treatment of acute myeloid leukemia and myelodysplastic syndrome.

PTK787/ZK 222584 (PTK/ZK) is an oral angiogenesis inhibitor targeting vascular endothelial growth factor (VEGF) receptor tyrosine kinases, including VEGFR-1/Flt-1, VEGFR-2/KDR, VEGFR-3/Flt-4, the platelet-derived growth factor receptor tyrosine kinase and the c-kit protein tyrosine kinase. The objective of this Phase I study was to evaluate the safety, tolerability, biologic activity and pharmacologic profile of PTK/ZK administered orally, twice daily, on a continuous dosing schedule in patients with primary refractory or relapsed acute myeloid leukemia (AML), secondary AML, poor-prognosis de novo AML or advanced myelodysplastic syndrome (MDS). Acute myeloid leukemia patients for whom PTK/ZK monotherapy was ineffective could receive PTK/ZK combined with standard induction chemotherapy. Sixty-three patients received PTK/ZK at doses of 500-1000 mg orally b.i.d. Safety and pharmacokinetic data were collected. Responses were evaluated according to standard bone marrow and peripheral blood criteria. At 1000 mg b.i.d., dose-limiting toxicities of lethargy, hypertension, nausea, emesis and anorexia were observed. Other adverse events related to PTK/ZK were dizziness, weakness, fatigue, diarrhea and pruritus; these were generally mild and reversible. Pharmacokinetic data showed that steady state was reached by day 14, there was no accumulation with repeat dosing and there was no significant increase in exposure at steady state beyond the maximum tolerated dose (MTD). Complete remission was observed in five of 17 AML patients treated with PTK/ZK combined with chemotherapy. In conclusion, the MTD of PTK/ZK is 750 mg orally b.i.d. The drug is generally well tolerated and can be given in combination with chemotherapy for patients with MDS and AML.

Lymphoproliferative diseases in immunocompromised hosts: the role of Epstein-Barr virus.

Epstein-Barr virus (EBV) is a ubiquitous transforming virus of the herpes group showing tropism for B lymphocytes. Primary infection in normal hosts results in a transient lymphoproliferative disorder, acute infectious mononucleosis (IM), that is restricted by cytotoxic and suppressive lymphocytes. However, in the immunodeficient host, EBV-induced lymphoproliferation may behave in a biologically malignant fashion. Patients with primary immunodeficiencies and those with immune incompetence resulting from suppressive therapy in allograft transplantation or infection with human immunodeficiency virus (HIV) have EBV-related illness ranging from fulminant mononucleosis and invasive polyclonal B cell hyperplasia to monoclonal B cell malignancies. While the direct link between EBV and malignant B cell proliferation in these patients has not been elucidated, the association has been increasingly recognized with improved techniques of viral detection. Clinical management can be guided by the location and extent of tumor, histologic features, and clonality. Regional and node-based polyclonal proliferations may respond to prompt reduction of immunosuppressive therapy and efforts to interrupt the replicative cycle with antiviral agents. Systemic cytotoxic therapy often leads to further immunosuppression and should be reserved for patients with progressive disease, advanced visceral involvement, and monoclonal lymphoid malignancies.

The myelodysplastic syndromes: biology and implications for management.

Since the initial efforts to characterize the myelodysplastic syndromes in 1976, an extensive body of information has accumulated defining biologic features and the relation to clinical aspects of disease. While the pathogenesis of these disorders remains incompletely understood, laboratory investigations indicate that they are clonal disorders affecting hematopoietic stem cells characterized by a progressive imbalance between self-renewal and differentiation. Despite karyotypic resemblance to acute myeloid leukemia, fundamental biologic differences may underly the disappointing results achieved to date with intensive chemotherapy. The recent availability of recombinant hematopoietic growth factors for use in clinical trials has shown that the maturation defect in many instances can be overcome with administration of lineage-restricted recombinant hematopoietins. Routine use of these promising agents must await results of randomized clinical trials to determine the impact of prolonged treatment on leukemic evolution and disease-related morbidity.

Lung cancer in Hodgkin's disease: association with previous radiotherapy.

Seven cases of lung cancer were observed in patients with Hodgkin's disease (HD) since 1970. The risk ratio for the development of lung cancer among HD patients was 5.6 times that expected in the general population. The pertinent clinical data from these patients are described and compared to 28 additional patients reported from other institutions. Small-cell lung cancer represented the predominant histologic type of lung cancer encountered in both smoking and nonsmoking patients with HD, accounting for 42% of cases overall and greater than 55% of cases reported in reviews of second malignancies. Tobacco use was noted in only 53% of patients. Twenty-eight (94%) of 30 patients developing metachronous lung cancer received supradiaphragmatic irradiation as primary therapy for HD. Nineteen (68%) of these patients received subsequent chemotherapy salvage. The median age at diagnosis of HD and lung cancer was 39 and 45 years, respectively. The interval between diagnosis of HD and metachronous lung cancer averaged seven years but appeared to vary inversely with age. HD patients treated with supradiaphragmatic irradiation or combined modality therapy may be at increased risk for developing lung cancer. The high frequency of in-field malignancies that we observed and the prevalence of small-cell lung cancer in both smoking and nonsmoking patients suggests that chest irradiation may influence the development of metachronous lung cancer in these patients. The finding of a mean latent interval in excess of seven years emphasizes the need for close long-term observation.

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in small-cell lung cancer.

Review of clinical data from 350 patients with small-cell lung cancer (SCLC) revealed hyponatremia (sodium less than 130 mEq/L) attributable to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in 40 patients (11%). Although hyponatremia was severe in most instances (median, sodium 117 mEq/L), symptoms attributable to water intoxication were identified in only 27% of hyponatremic episodes. Development of SIADH showed no correlation with clinical stage, distribution of metastatic sites, sex, or histologic subtype of small-cell carcinoma. SIADH occurred most often with initial presentation (33 of 40), and resolved promptly (less than 3 weeks) with initiation of combination chemotherapy in 80% of evaluable patients. The presence of SIADH did not influence response to chemotherapy or overall survival as an independent variable. However, in five patients profound hyponatremia developed immediately following primary cytotoxic therapy (range, one to five days). Despite initial control of SIADH, dilutional hyponatremia recurred in 70% of patients with tumor progression. Our findings suggest that development of clinically demonstrable SIADH in patients with SCLC is dependent on functional properties of the neoplastic cells, rather than tumor burden or metastatic site. The potential for development of clinically significant hyponatremia early in the course of cytotoxic therapy emphasizes the need to closely monitor patients, particularly those receiving chemotherapy regimens requiring substantial intravenous hydration.

Phase I/II trial of cyclosporine as a chemotherapy-resistance modifier in acute leukemia.

PURPOSE: To determine the toxicities and maximum-tolerated dose of cyclosporine (CsA) administered with daunorubicin as a modulator of multidrug resistance (MDR) in acute leukemia, and to evaluate response to treatment and its relationship to mdr1 gene expression. PATIENTS AND METHODS: Patients with poor-risk acute myeloid leukemia (AML) received sequential treatment with cytarabine (3 g/m2/d intravenously [i.v.]) days 1 to 5, and daunorubicin (45 mg/m2/d) plus CsA as a 72-hour continuous infusion (CI) days 6 through 8 in a phase I/II trial. A loading dose of CsA administered over 1 to 2 hours preceded the CI. CsA dose escalations ranged from 1.4 to 6 mg/kg (load) and 1.5 to 20 mg/kg/d (CI). Whole-blood concentrations of CsA were monitored by immunoassay; plasma concentration of daunorubicin and daunorubicinol were determined by high-pressure liquid chromatography (HPLC). Specimens were analyzed for P-glycoprotein expression, and results confirmed by a quantitative RNA polymerase chain reaction (PCR) assay for the mdr1 gene transcript. RESULTS: Forty-two patients are assessable for toxicity and response. P-glycoprotein was detected in 70% of cases. Dose-dependent CsA toxicities included nausea and vomiting (22%), hypomagnesemia (61%), burning dysesthesias (21%), and prolongation of myelosuppression. Transient hyperbilirubinemia developed in 62% of treatment courses and was CsA-dose-dependent. Reversible azotemia occurred in three patients receiving concurrent treatment with potentially nephrotoxic antibiotics. Steady-state blood concentrations of CsA > or = 1,500 ng/mL were achieved in all patients receiving CI doses > or = 16 mg/kg/d. Mean plasma daunorubicin, but not daunorubicinol, levels were significantly elevated in patients who developed hyperbilirubinemia (P = .017). Twenty-six (62%) patients achieved a complete remission (CR) or restored chronic phase and three patients achieved a partial remission (PR) for an overall response rate of 69% (95% confidence interval, 54% to 84%). The response rate was higher in patients who developed hyperbilirubinemia (P = .001), whereas MDR phenotype did not influence response to treatment. Among five patients with MDR-positive leukemia, cellular mdr1 mRNA decreased (n = 1) or was absent from relapsed specimens (n = 4), while mdr1 RNA remained undetectable at relapse in two patients who were MDR-negative before treatment. CONCLUSION: High doses of CsA, which achieve blood concentrations capable of reversing P-glycoprotein-mediated anthracycline resistance in vitro, can be incorporated into induction regimens with acceptable nonhematologic toxicity. Transient hyperbilirubinemia occurs commonly with CsA administration and may alter daunorubicin pharmacokinetics. Recommended doses of CsA for phase II and III trials are a load of 6 mg/kg and CI of 16 mg/kg/d.

Phase I/II study of the P-glycoprotein modulator PSC 833 in patients with acute myeloid leukemia.

PURPOSE: To determine the maximum-tolerated dose, pharmacokinetic interaction, and activity of PSC 833 compared with daunorubicin (DNR) and cytarabine in patients with poor-risk acute myeloid leukemia. PATIENTS AND METHODS: Patients received ara-C 3 g/m(2)/d on 5 consecutive days, followed by an IV loading dose of PSC 833 (1.5 mg/kg) and an 84-hour continuous infusion escalating from 6, 9, or 10 mg/kg/d. Daunorubicin was administered as a 72-hour continuous infusion at 34 or 45 mg/m2/d [corrected]. Responding patients received consolidation chemotherapy with DNR pharmacokinetics performed without PSC-833 on day 1, and with PSC-833 on day 4. Response was correlated with expression of P-glycoprotein and lung resistance protein (LRP), and in vitro sensitization of leukemia progenitors to DNR cytotoxicity by PSC 833. RESULTS: All 43 patients are assessable for toxicity and response. Grade 3 or greater hyperbilirubinemia (70%) was the only dose-dependent toxicity. Four patients (9%) succumbed to treatment-related complications. Twenty-one patients (49%) achieved a complete remission or restored chronic phase, including 10 of 20 patients treated at the maximum-tolerated dose of 10 mg/kg/d of PSC-833 and 45 mg/m(2) of DNR. The 95% confidence interval for complete response was 33.9% to 63.7%. Administration of PSC 833 did not alter the mean area under the curve for DNR, although clearance decreased approximately two-fold (P =.04). Daunorubicinol clearance decreased 3.3-fold (P =.016). Remission rates were not effected by mdr-1 expression, but LRP overexpression was associated with chemotherapy resistance. CONCLUSION: Combined treatment with infused PSC 833 and DNR is well tolerated and has activity in patients with poor risk acute myeloid leukemia. Administration of PSC 833 delays elimination of daunorubicinol, but yields variable changes in DNR systemic exposure.

Non-Hodgkin's lymphoma of the gastrointestinal tract: an analysis of clinical and pathologic features affecting outcome.

Clinical and histopathologic data from 87 patients with primary non-Hodgkin's lymphoma of the gastrointestinal (GI) tract diagnosed between 1974 and 1984 were reviewed. B-cell lymphomas of intermediate- or high-grade histology constituted 78% of lesions. Stage of disease varied with histologic grade, with a preponderance of advanced disease (stages IIIE and IV) in patients with low-grade lymphoma (15 of 21) (71%), compared with higher grade lesions (38%, P = .01). Among patients with nonlocalized (stages IIE through IV) lymphoma of intermediate- or high-grade histology, surgical resection of the primary focus afforded a higher rate of complete remission (CR) (70% v 50%) and sustained CR (61% v 21%, P = .04) after cytotoxic therapy compared with the nonresected cohort. The median survival in the resected group was 51 months + compared with 13 months in the nonresected patients (P = .012). Differences in outcome were attributable to a high risk of treatment-related complications (perforation and/or hemorrhage) (43% v 0%, P = .001) and local relapse (29% v 4%, P = .05) in nonresected individuals. Life-threatening local complications were not observed in patients with low-grade lymphoma managed solely with medical therapy. Histologic findings from surgically staged patients identified presence of extravisceral disease and intermediate- or high-grade tumor histology as features predictive of transmural invasion, enabling potential identification of patients who might be optimally managed by resection of the primary GI focus before initiation of cytotoxic therapy.

Acanthocytosis associated with myelodysplasia.

Dysplastic hematopoiesis associated with erythrocyte macrocytosis is a morphologic hallmark of myelodysplasia. We report the cases of six patients with myelodysplasia in which acanthocytosis was the predominant red blood cell (RBC) abnormality. In each case acanthocytes represented 5% to 10% of circulating RBC forms and was the primary reason for referral in two cases. None of the patients had comorbid conditions known to be associated with acanthocyte formation. Myelodysplasia should be considered in the differential diagnosis of acanthocytosis, particularly in the anemic, elderly individual. Acanthocytosis may be a harbinger of an unrecognized, hematologic stem-cell disorder.

Role of multidrug resistance and its pharmacological modulation in acute myeloid leukemia.

Cellular expression of the multidrug transporter, P-glycoprotein (Pgp) is recognized as a biological mechanism possibly contributing to treatment failure in acute myeloid leukemia (AML). Correlative studies indicate its association with poor risk features including secondary AML, CD34+ surface phenotype, unfavorable karyotype and advanced age. Reported disparity in the prognostic impact of Pgp relates in part to variance in drug transport capacity. In Pgp expressing cells, capacity for drug extrusion is governed by maturation phenotype and is largely restricted to CD34+ populations lacking myeloid maturation antigens. Three competitive inhibitors of Pgp function showing promise in pilot studies, cyclosporin A (CsA), quinine and the cyclosporin D analogue PSC 833, have entered testing in phase III trials. The presence of non-Pgp-related mechanisms of multidrug resistance, relatively insensitive to Pgp modulators, may limit the success of such treatment strategies. Preliminary investigations indicate that overexpression of the gene encoding the multidrug resistance-related protein (MRP) occurs infrequently in de novo AML, but relative increases in gene message are evident in relapsed specimens. Overexpression of lung resistance protein (LRP) is associated with adverse prognostic variables such as age, secondary disease and Pgp, and has demonstrated prognostic relevance. Because treatment with Pgp modulators may select for this drug resistance phenotype, LRP merits evaluation in randomized trials of Pgp antagonists. These observations indicate that multiple biological mechanisms contribute to anthracycline resistance in AML, thereby warranting development of multifunctional modulators or chemotherapeutic agents with novel mechanisms of action.

The role of multidrug resistance and its pharmacological modulation in acute myeloid leukemia.

Despite more effective treatment for younger patients with acute myeloid leukemia (AML), resistance to conventional antineoplastics has limited such advances in the elderly. Overexpression of the multidrug transporter, P-glycoprotein (Pgp), appears to contribute to treatment failure in de novo AML and has been detected in up to 70 percent of elderly patients. Data also indicate linkage between Pgp and many adverse prognostic features, including cytogenetic pattern, surface phenotype, and evolution from an antecedent hematologic disorder. Pharmacologic inhibitors of Pgp function have been targeted for investigation in elderly AML patients. Non-Pgp mechanisms responsible for multidrug resistance (MDR) phenotypes that are only weakly sensitive to classic Pgp modulators, however, may limit the success of such strategies. Overexpression of the lung-resistance protein (LRP) in AML has also been linked to advanced age, secondary leukemia, and Pgp overexpression. In a study of 66 patients at the Arizona Cancer Center, LRP overexpression was a more important predictor of response to induction therapy for AML than was Pgp. Recent investigations indicate that overexpression of the gene encoding the MDR-related protein (MRP), though rare in de novo AML, may be common in high-risk groups such as relapsed patients and secondary AML. Use of monoclonal antibodies specific for the MRP gene product may further define its prognostic relevance in AML.

Amifostine stimulates formation of multipotent and erythroid bone marrow progenitors.

Amifostine (WR-2721, Ethyol) is a phosphorylated aminothiol that affords broad cytoprotection from the myelosuppressive effects of antineoplastics. To further characterize its hematopoietic activities, we investigated the effects of amifostine and its dephosphorylated metabolite, WR1065, on the in vitro growth of human bone marrow progenitors. Preincubation exposure to amifostine or WR1065 stimulated the growth of colony-forming units granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM) and erythroid bursts (BFU-E) from bone marrow mononuclear cells in a dose-dependent fashion. Over the concentration range tested (0.1-1000 microM), pretreatment with the aminothiols enhanced formation of CFU-GEMM up to five-fold and BFU-E nine-fold, compared to a three-fold increase in myeloid colony recovery. In CD34+ selected cells, preincubation with amifostine increased formation of CFU-GEMM up to 38-fold and produced macroscopic colonies, exceeding colony number in cultures initiated with optimal concentrations of interleukin-1 (IL-1), IL-3, or kit ligand (KL). When compared with recombinant human cytokines, amifostine enhanced IL-1 and IL-3 induced colony formation, although its stimulatory effect was less than additive. In contrast, pretreatment with amifostine antagonized the stimulatory effects of KL, whereas synergy was observed with concurrent exposure. Ex vivo expansion studies showed that amifostine alone supported and augmented the production of myeloid progenitors in secondary cultures. Similarly, under cytokine-deficient conditions, amifostine promoted cell survival and delayed apoptosis as measured by nucleosome generation. These data indicate that amifostine is a novel multipotent hematopoietic stimulant that augments the formation and survival of bone marrow progenitors.

Deficient tumor-infiltrating T-lymphocyte response in malignant lymphoma: relationship to HLA expression and host immunocompetence.

Tumor-infiltrating T-lymphocytes (T-TIL) are putative mediators of tumor containment that exhibit unique specificity for autologous tumor cells. The magnitude of T-TIL response in biopsy specimens from patients with B-cell lymphoma has been suggested as an independent predictor of clinical outcome. Since recognition of tumor antigens may occur in association with major histocompatibility complex (MHC) molecules, effective T-TIL tumor immunosurveillance may be limited by either failure to express MHC-encoded recognition structures and/or host T-cell immunocompetence. To further delineate T-cell immunoregulation in B-cell lymphoma, we assessed T-TIL fraction and tumor expression of invariant class I and class II HLA determinants by immunohistochemistry in biopsy specimens. Two distinct clinical cohorts of B-cell lymphoma were investigated to delineate pathogenetic differences in T-TIL response. One group, representing immunodeficient and transplant-related lymphomas, comprised 18 patients with AIDS- or allograft-related lymphoma. The second group comprised 83 consecutive cases of sporadic diffuse large cell (DLCL) lymphoma. Median CD8+ T-TIL was significantly lower (4.9% versus 12.7%) among immunodeficiency-associated lymphoma and the frequency of cases with low (< 6%) CD8+ T-TIL greater (76% versus 23%) (p < 0.0001). None of the immunodeficiency-associated lymphomas demonstrated non-polymorphic HLA loss. Absence of one or more class I or II HLA determinants was found in 13 out of 19 (68%) sporadic DLCL specimens with low CD8+ T-TIL, compared to 20% of cases with higher T-TIL fraction (p = 0.0004). These findings implicate impaired host immunosurveillance in deficient T-TIL response in immunodeficiency-associated B-cell lymphoma, whereas low T-TIL in sporadic cases of DLCL relates to tumor loss of HLA determinants. Strategies to modulate tumor HLA expression or augment antitumor response merit investigation in patients with B-cell lymphoma.

Mast cell growth factor (c-kit ligand) restores growth of multipotent progenitors in myelodysplastic syndrome.

In vitro growth of primitive hematopoietic progenitors is severely impaired in the myelodysplastic syndromes (MDS). To determine if the c-kit ligand mast cell growth factor (MGF) can improve progenitor growth in MDS, we evaluated in vitro responsiveness of bone marrow progenitors from 25 patients to MGF and/or GM-CSF, interleukin-3 (IL-3) and PIXY 321, and examined the relationship between progenitor response and cellular expression of the c-kit receptor. MGF and erythropoietin gave rise to macroscopic colonies and dose-dependently increased CFU-GEMM and BFU-E up to 27-fold in 15 (60%) and 20 (80%) patients, respectively. Among 17 patients with absent growth in lymphocyte-conditioned media, MGF stimulated CFU-GEMM recovery in 59%, compared to 23% with PIXY 321, 12% with IL-3 and 8% with GM-CSF. Cytokine combinations did not augment recovery of erythropoietin-dependent progenitors above that achieved with MGF alone. MGF and/or IL-3 were comparatively weak stimulants of CFU-GM formation, whereas GM-CSF and PIXY in combination with MGF increased colony number 2- to 15-fold in 60 and 70% of patients, respectively, while preserving maturation competence as evidenced by colony composition and increased colony/cluster ratio. The stimulatory effects of MGF were observed in all morphologic categories of MDS except chronic myelomonocytic leukemia. A mononuclear cell population expressing the c-kit receptor was identified by flow cytometry in 57% of cases. Neither SR-1 reactivity nor cytogenetic pattern predicted progenitor response to MGF. These data indicate that MGF improves the colony-forming capacity of hematopoietic progenitors in MDS and is a potent co-stimulant of multipotent and committed progenitor recovery. The heterogeneity in MGF responsiveness implies an intrinsic defect in growth regulation not explained by cellular loss of c-kit display.

An international data set for CMML validates prognostic scoring systems and demonstrates a need for novel prognostication strategies.

Since its reclassification as a distinct disease entity, clinical research efforts have attempted to establish baseline characteristics and prognostic scoring systems for chronic myelomonocytic leukemia (CMML). Although existing data for baseline characteristics and CMML prognostication have been robustly developed and externally validated, these results have been limited by the small size of single-institution cohorts. We developed an international CMML data set that included 1832 cases across eight centers to establish the frequency of key clinical characteristics. Of note, we found that the majority of CMML patients were classified as World Health Organization CMML-1 and that a 7.5% bone marrow blast cut-point may discriminate prognosis with higher resolution in comparison with the existing 10%. We additionally interrogated existing CMML prognostic models and found that they are all valid and have comparable performance but are vulnerable to upstaging. Using random forest survival analysis for variable discovery, we demonstrated that the prognostic power of clinical variables alone is limited. Last, we confirmed the independent prognostic relevance of ASXL1 gene mutations and identified the novel adverse prognostic impact imparted by CBL mutations. Our data suggest that combinations of clinical and molecular information may be required to improve the accuracy of current CMML prognostication.