PURPOSE Colony-stimulating factor-3 receptor ( CSF3R)-T618I is a recurrent activating mutation in chronic neutrophilic leukemia (CNL) and to a lesser extent in atypical chronic myeloid leukemia (aCML) resulting in constitutive JAK-STAT signaling. We sought to evaluate safety and efficacy of the JAK1/2 inhibitor ruxolitinib in patients with CNL and aCML, irrespective of CSF3R mutation status. METHODS We conducted a phase II study of ruxolitinib in 44 patients (21 CNL and 23 aCML). The primary end point was overall hematologic response rate (ORR) by the end of 6 continuous 28-day cycles for the first 25 patients enrolled. We considered a response as either partial (PR) or complete response (CR). We expanded accrual to 44 patients to increase our ability to evaluate secondary end points, including grade ≥ 3 adverse events, spleen volume, symptom assessment, genetic correlates of response, and 2-year survival. RESULTS ORR was 32% for the first 25 enrolled patients (8 PR [7 CNL and 1 aCML]). In the larger cohort of 44 patients, 35% had a response (11 PR [9 CNL and 2 aCML] and 4 CR [CNL]), and 50% had oncogenic CSF3R mutations. The mean absolute allele burden reduction of CSF3R-T618I after 6 cycles was greatest in the CR group, compared with the PR and no response groups. The most common cause of death is due to disease progression. Grade ≥ 3 anemia and thrombocytopenia were observed in 34% and 14% of patients, respectively. No serious adverse events attributed to ruxolitinib were observed. CONCLUSION Ruxolitinib was well tolerated and demonstrated an estimated response rate of 32%. Patients with a diagnosis of CNL and/or harboring CSF3R-T618I were most likely to respond.
We have studied the effect of recombinant human hematopoietic growth factors (interleukin-3 [rhIL-3], granulocyte-macrophage colony- stimulating factor [rhGM-CSF], and granulocyte CSF [rhG-CSF]) on the clonal growth of human colon adenocarcinoma cell lines HTB-38, CCL 187, and WiDr (CCL 218). The factors stimulated clonal growth of HTB-38 and CCL 187 in a capillary modification of the human tumor clonogenic assay in agar up to twofold. There were dose-response correlations over a range of 1 to 10,000 U/mL for rhIL-3, rhGM-CSF, and rhG-CSF. Incubation with neutralizing monoclonal antibodies abolished the stimulation of clonal growth by rhGM-CSF. The WiDr cell line was nonresponsive to rhIL- 3 and rhGM-CSF. These results represent the first evidence that a variety of hematopoietic growth factors can stimulate the growth of clonogenic cells of some nonhematopoietic malignant cell lines in vitro.
Two major types of lymphocytosis of large granular lymphocytes (LGLs) were observed. The proliferating LGLs in each type had distinct immunophenotypes, functional characteristics, and probably belonged to different cell lineages. The more common form (Type A) consisted of cells derived from the T cell lineage and had the T suppressor/cytotoxic phenotype (T11+, T3+, T8+). The expression of the Leu 7 and HLA-DR antigen was variable. These cells did not have natural killer (NK) function but showed a variable degree of antibody-dependent cell-mediated cytotoxic (ADCC) activity. Neutropenia was invariably present and rheumatoid arthritis and autoantibodies were frequent associations. These lymphocytes had many similarities to the major type of LGLs present in normal adult bone marrow. The other type of LGL lymphocytosis (Type B) consisted of cells lacking the antigens T3 and T8 but expressing M1 and NKH1. These cells possessed strong NK and ADCC activity but their cell lineage was not clear. Neutropenia and autoimmune phenomena were not detected. The cytochemical characteristics of the LGL granules from both types of patients were similar but differences in ultrastructure were observed. LGLs from Type B patients proliferated in the presence of Interleukin 2 (IL-2) and 12- O-tetradecanoyl-phorbol-13 acetate (TPA). Significant changes in their basic T11+, T3-, T8- phenotype were not observed. IL-2 and TPA, however, had profound influence on the NK function of the cells with enhancement in the case of IL-2 and marked suppression when stimulated by TPA.
A comprehensive supportive care approach was associated with a low treatment-related mortality rate of less than 1%. With the observed reduction in treatment-related mortality, it is reasonable to evaluate the efficacy of HDC in women with less than 10 positive nodes and stage II disease in well-designed clinical trials.
Recombinant human interleukin-6 (IL-6) has previously been shown to increase platelet counts in mice and primates. To elucidate the mechanisms underlying this phenomenon, serial analyses were performed on megakaryocytes obtained from rhesus monkeys treated for 8 days with 30 micrograms/kg/d of recombinant human IL-6. Platelet counts increased to a maximum of 7.8 x 10(5)/microL with biphasic peaks on days 7 and 12 without significant changes in platelet volumes. Large increases in DNA content were seen by two-color flow cytometry and digital image analysis. Ploidy distribution underwent a significant shift between study days 3 and 11 (P less than .0001) with large increases in the frequency of 64N and 128N megakaryocytes. The modal ploidy increased from the normal 16N to 64N. Megakaryocyte size, as measured by area, was increased 2- to 2.7-fold. On day 3, multiple megakaryocytes were seen in endomitosis, along with an abundance of young cells with wide, organelle-free peripheral zones. The giant megakaryocytes seen on days 5 to 7 exhibited marked membrane hyperplasia that occupied much of the cell. Emperipolesis occurred frequently, as did megakaryocyte cell death. No giant platelets were seen. We conclude that IL-6 significantly alters the process of megakaryocyte maturation and thrombocytopoiesis, and that these effects, at least in the doses of IL- 6 administered, should not be equated with the physiologic mechanisms operative during accelerated platelet production.
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