Reinduction therapy in 297 children with acute lymphoblastic leukemia in first bone marrow relapse: a Pediatric Oncology Group Study

Many children with acute lymphoblastic leukemia (ALL) develop a marrow relapse during or shortly following initial continuation chemotherapy. Achievement of a second complete remission is the initial step in a successful retreatment effort. Reinduction results using two or three drugs have been unsatisfactory, and previous reports of four-drug reinduction programs have included relatively small numbers of patients. Pediatric Oncology Group protocol 8303 was designed for patients with ALL in first marrow relapse during or within 6 months after cessation of chemotherapy. The results of reinduction therapy in 297 study patients are described here. Four-drug reinduction therapy consisted of daily oral prednisone, weekly vincristine and daunorubicin, and asparaginase three times weekly for 4 weeks (PVDA). CNS retreatment consisted of two doses of triple intrathecal chemotherapy. Of the 297 patients receiving reinduction, 245, or 82%, entered second complete remission, six died of infection or progressive disease, and 46 others still had M2 or M3 bone marrow status. Forty of these latter patients received four doses (during a 2-week period) of teniposide and cytarabine, after which 13 (32%) achieved complete remission status. Thus, the overall second complete remission rate with PVDA with or without teniposide/cytarabine was 258 of 297, or 87%. The treatment program was generally well tolerated. Among the numerous factors analyzed by using logistic regression, only female sex (P = .035), the presence of blasts on the blood smear at the time of relapse (P = .0002), and a length of initial complete remission less than 12 months (P = .021) were independent predictors of failure to enter second remission. We conclude that the intensive reinduction program described here is a highly effective first step in the delivery of salvage therapy to patients with ALL in first marrow relapse. The current challenge is to develop improved continuation treatment for these children.     

Human platelet surface binding of endogenous secreted factor VIII-von Willebrand factor and platelet factor 4

Washed human platelets in buffers containing either 2 mM Ca++ or 4 mM EDTA were stimulated by human alpha-thrombin to induce secretion. The binding of two endogenous secreted proteins, factor-VIII-related protein (VIII-R) (von Willebrand factor) and platelet factor 4, was measured by reacting thrombin-treated and control platelets with specific antibodies to these proteins, then quantifying antibody binding with 125I-staphylococcal protein A. Both of these granule proteins were associated with the platelet membrane surface by a calcium-dependent mechanism after thrombin-induced secretion. This ability to bind endogenous secreted proteins to the plasma membrane surface may provide a mechanism by which the platelet can concentrate and organize its secreted proteins for subsequent physiologic reactions.     

Two new sickle cell syndromes: HbS, Hb Camden, and alpha-thalassemia; and HbS in combination with Hb Tacoma

Hemoglobin variants having electrophoretic mobility more rapid than that of HbA were identified in combination with sickle hemoglobin in two patients at the Cook County Hospital. Neither individual had symptomatic hematologic disease. In one patient, the rapidly migrating hemoglobin had the amino acid substitution characteristic of Hb Tacoma (beta-40 arg leads to ser), a mildly unstable variant. In the other patient, Hb Camden (beta-131 gln leads to glu) was identified, and the hematologic findings also indicated that he has alpha-thalassemia trait. In the patient with HbS-Camden--alpha-thalassemia, globin synthesis was unbalanced (alpha/beta 0.66), and HbS represented only 19.5% of the total hemoglobin. The latter finding suggests that under conditions of limited alpha-chain availability beta Camden may combine with alpha subunits at least as efficiently as does betaA. HbS represented 56% of the hemoglobin of the patient with HbS Tacoma, although the rate of synthesis of beta Tacoma by her reticulocytes was consistently greater than that of betaS. A time-course synthesis study demonstrated a progressive increase in the specific activity of beta Tacoma in relation to that of betaS, suggesting that the unstable beta- chains of Hb Tacoma underwent selective intracellular degradation. This process appears to explain the disparity between the rates of synthesis of the two beta chains and the relative representation of HbS and Hb Tacoma in the patient's erythrocytes.     

Enhancement of hemopoietic recovery after bone marrow transplantation with the addition of nucleated blood cells in mice

Recovery of bone marrow cellularity, CFU-C, and CFU-S were studied sequentially over 90 days time after syngeneic bone marrow transplantation in mice. A minimal cell dose of 2 X 10(5) bone marrow cells was given. At day 28 after transplantation, CFU-C reached more than 50% of the normal range whereas the CFU-S concentration was less than 15%. Normalization of CFU-S occurred at day 90. The effect of the addition of peripheral blood nucleated cells on bone marrow hemopoietic recovery was studied at day 28. The augmentation of CFU-C and CFU-S recoverey were dose dependent. Optimal enhancement was seen with bone marrow to blood ratios of 1:1 and 1:2.5. This enhancement effect was lost when nucleated blood cells in a ratio of 1:10 were administered.     

Biochemical, immunological, and in vivo functional characterization of B-domain-deleted factor VIII

Coagulation factor VIII (FVIII) is a cofactor in the intrinsic pathway of blood coagulation for which deficiency results in the bleeding disorder hemophilia A. FVIII contains a domain structure of A1-A2-B-A3- C1-C2 of which the B domain is dispensable for procoagulant activity in vitro. In this report, we compare the properties of B-domain-deleted FVIII (residues 760 through 1639, designated LA-VIII) to wildtype recombinant FVIII. In transfected Chinese hamster ovary (CHO) cells, LA- VIII was expressed at a 10- to 20-fold greater level compared with wildtype FVIII. The specific activity of purified LA-VIII was indistinguishable from wild-type recombinant FVIII and both exhibited similar thrombin activation coefficients. Wildtype recombinant-derived FVIII and LA-VIII also displayed similar timecourses of thrombin activation and heavy chain cleavage. However, compared with wildtype recombinant-derived FVIII, the light chain of LA-VIII was cleaved fivefold more rapidly by thrombin. Addition of purified von Willebrand factor (vWF) did not alter the kinetics of thrombin cleavage or activation of either wildtype recombinant-derived FVIII or LA-VIII. The immunogenicity of LA-VIII was compared with wildtype FVIII in a novel model of neonatal tolerance induction in mice. The results did not detect any immunologic differences between wildtype FVIII and LA-VIII, suggesting that LA-VIII does not contain significant new epitopes that are absent in wildtype FVIII. LA-VIII was tolerated well on infusion into FVIII-deficient dogs and was able to correct the cuticle bleeding time similar to wildtype recombinant factor VIII. In vivo, LA-VIII was bound to canine vWF and exhibited a half-life similar to wildtype recombinant FVIII. These studies support that B-domain-deleted FVIII may be efficacious in treatment of hemophilia A in humans.     

A randomized, parallel study of the safety and efficacy of 45 mg primaquine versus 75 mg bulaquine as gametocytocidal agents in adults with blood schizonticide-responsive uncomplicated falciparum malaria [ISCRTN50134587]

Background  

The WHO recommends that adults with uncomplicated P. falciparum successfully treated with a blood schizonticide receive a single dose of primaquine (PQ) 45 mg as a gametocytocidal agent. An earlier pilot study suggested that 75 mg of bulaquine (BQ), of which PQ is a major metabolite, may be a useful alternate to PQ.     

Subsecond calcium dynamics in ADP- and thrombin-stimulated platelets: a continuous-flow approach using indo-1

The regulation and kinetics (less than 5 seconds) of cytosolic calcium changes ([Ca2+]i) in stimulated blood platelets have been investigated under physiological blood flow conditions. Using a newly-developed continuous-flow approach with indo-1-loaded human platelets, adenosine diphosphate (ADP, 10 mumol/L) and thrombin (5 U/mL) were equally effective in significantly increasing [Ca2+]i by 0.5 seconds. ADP induced a transient [Ca2+]i peak of 1 to 2 mumol/L near 2 seconds, whereas thrombin caused a sustained and larger response. The first phase (less than 2 seconds) was not influenced by a lack of extracellular Ca2+, in contrast to the subsequent [Ca2+]i increase that only reached about 0.7 mumol/L for either ADP or thrombin. The shear rates used in our continuous-flow apparatus were physiological (less than 1,258 sec-1) and only slightly increased the basal [Ca2+]i of 0.1 mumol/L. Platelet aggregation (less than 5 seconds), assessed by single- particle counting, was not altered in platelets loaded with indo-1/AM (2.5 mumol/L).     

Characterization of endogenous cytokine concentrations after high-dose chemotherapy with autologous bone marrow support

Endogenous cytokines are thought to mediate numerous biologic processes and may account for some adverse effects experienced following the administration of recombinant proteins. This study describes the pattern of endogenous cytokine exposure following high-dose chemotherapy. Blood concentrations of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), macrophage colony-stimulating factor (M-CSF), and erythropoietin (EPO) were measured by enzyme-linked immunosorbent assay (ELISA) methods in 68 patients receiving the same ablative chemotherapy regimen (cyclophosphamide, cisplatin, carmustine). Patients were grouped according to cellular support (autologous bone marrow [BM] CSF-primed peripheral blood progenitor cells [PBPCs]) and prescribed growth factor (recombinant human granulocyte or granulocyte-macrophage colony-stimulating factor [rHuG- CSF or rHuGM-CSF]). Leukocyte reconstitution was most accelerated in the groups treated with PBPCs and rHuG-CSF. IL-6, M-CSF, and TNF-alpha concentrations were higher in the groups treated with rHuGM-CSF and without PBPCs. Maximal endogenous cytokine concentrations occurred approximately 12 days after BM reinfusion. High concentrations of EPO occurred in patients experiencing significant hypotension despite routine transfusions for hematocrit < 42%. High M-CSF and IL-6 levels were associated with increased platelet transfusion requirements. Concentrations of all four cytokines were significantly higher in patients experiencing renal or hepatic toxicity, with elevations occurring in a predictable sequence and M-CSF elevations occurring first. This report shows that endogenous cytokine concentrations may be influenced by either cellular or CSF support and are associated with differences in platelet reconstitution and organ toxicity.     

Monoclonal antibody to an epitope on the heavy chain of factor IX missing in three hemophilia-B patients

A murine hybridoma cell line that produces a monoclonal IgG1 antibody to human factor IX was established to provide a conformational probe for the clotting factor and its genetic variants. The antibody inhibited factor IX procoagulant activity, but did not appreciably interfere with the cleavage of factor IX by factor XIa nor with the binding of antithrombin-III-heparin complex to factor IXa. The antigen- solid-phase-antibody complex could be readily dissociated by relatively low concentrations of guanidine or sodium dodecyl sulfate, but only partially by high concentrations of urea. After gel electrophoresis and blotting of reduced samples of factor IXa, the antibody bound exclusively to the heavy chain. Sensitive immunoradiometric assays were developed using insolubilized monoclonal or polyclonal antibodies. Bovine factor IX had little cross-reactivity with the monoclonal antibody. Of 55 patient samples representing different pedigrees with hemophilia-B, antigen levels by the two assays were in excellent agreement in 49. There were 2 severely affected patients whose levels were too low to quantitate in the monoclonal antibody assay. A third, who had the lowest level of all by polyclonal antibody testing, and 3 less severely affected patients had no detectable antigen in the monoclonal antibody assay system (less than 0.03 U/dl). The latter 3 had at least 100-500 times as much antigen by polyclonal antibody testing. It is proposed that these 3 individuals have structural defects involving the epitope recognized by the monoclonal antibody and that they are due to amino acid substitutions between residues 188 through 359. Furthermore, it is suggested the substitutions lead to abnormal kinetic properties.     

Early recurrence or persistence of autoimmune diseases after unmanipulated autologous stem cell transplantation

Autologous stem cell transplantation with or without in vitro lymphocyte depletion has been suggested as a new treatment option for severe autoimmune diseases. We describe five patients with autoimmune diseases (CREST syndrome, myasthenia gravis and Hashimoto's thyroiditis, systemic lupus erythematosus, atopic dermatitis, and rheumatoid arthritis) who underwent autologous bone marrow (n = 1) or peripheral blood progenitor cell (n = 4) transplantation with unmanipulated grafts as treatment for the autoimmune disease in one case or as treatment for a malignant disorder with a concomitant autoimmune disorder in four cases. In all patients serological and clinical signs of the autoimmune disease recurred early or persisted. These observations should be regarded as a cautionary note concerning the efficacy of high-dose therapy followed by transplantation of unmanipulated autologous stem cells for treatment of severe autoimmune diseases.