Safety analysis of rFVIIa with emicizumab dosing in congenital hemophilia A with inhibitors: Experience from the HAVEN clinical program

BACKGROUND

Recombinant activated factor VII (rFVIIa; eptacog alfa activated, NovoSeven® , Novo Nordisk A/S) is a bypassing agent used in congenital hemophilia A patients with inhibitors. Emicizumab (Hemlibra® ; F Hoffmann-La Roche Ltd) is a recombinant, humanized, bispecific monoclonal antibody used for routine prophylaxis in patients with congenital hemophilia A with inhibitors. Concomitant use of the hemostatic agents rFVIIa and emicizumab carries a theoretical increased risk of thrombotic complications. Roche and Novo Nordisk collaboratively analyzed all available data on the use of rFVIIa in patients receiving emicizumab prophylaxis in the Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of Prophylactic Emicizumab Versus no Prophylaxis in Hemophilia A Participants With Inhibitors (HAVEN) clinical development program.

OBJECTIVE

Obtain further insights into the concomitant clinical use and safety of rFVIIa and emicizumab.

METHODS

The initial individual rFVIIa dose, dosing intervals and cumulative dosing were evaluated in the HAVEN 1, HAVEN 2, and HAVEN 4 trials. All adverse events reported in each of the three trials in patients treated with rFVIIa, including available narratives, were assessed.

RESULTS

The vast majority of bleeds occurred in HAVEN 1. When rFVIIa was used to treat a bleeding episode, a 100 ± 20 μg/kg dose was used to initiate treatment in the majority of cases. The dosing interval, as well as cumulative dosing were consistent with prescribing information and current practice. No serious adverse events, no thrombotic microangiopathy cases, or thromboembolic events were assessed to be associated with rFVIIa when used in conjunction with emicizumab prophylaxis in the HAVEN trials.

CONCLUSION

rFVIIa use in the context of emicizumab prophylaxis does not change the rFVIIa safety profile as described in the product information.

The Upward Spiral of Drug Costs: A Time Series Analysis of Drugs Used in the Treatment of Hemophilia

Hemophilia is an expensive disease because its treatment is heavily dependent on costly clotting factor drugs. Over the last nine years, a consortium of three Comprehensive Hemophilia Treatment Centers and other hospitals, which purchased clotting factors for their patients, has seen treatment costs escalate on average 17% annually. Currently, new, even more expensive drugs are entering the market.

This study analyzes 3,244 purchases that were made over a nine-year period totaling nearly 500 million units of clotting factor, representing every product on the market. Purchases were made both apart from and under the Federal Public Health Service (PHS) discount pricing rules.

The main cause of the increases was the move to newer, more expensive products. The average price of existing products increased less than 2% per year, but new products were priced, on average, 47% higher than existing products. Overall consumption increased by an average of 5% per year, likely reflecting prophylactic treatment modalities that require greater amounts of clotting factor. Government pricing programs, such as the PHS program, were ineffective or counterproductive at reducing costs.There is a notable absence of competition in this market, with a few dominant companies having a functional monopoly in the largest segments of the market. Prices of older products are not lowered, even when new products are brought to market. A few products that serve small patient groups have had their prices increased substantially.

This escalation is likely to continue as new, more expensive clotting factor drugs are developed. Since these new products are not proven to be any safer or more effective than the current products, this situation creates a risk of intervention by government and insurers to address both treatment costs and exhaustion of patients’ insurance caps. Drug companies are not serving the patients by pricing new, but often very similar, products so aggressively. The trends seen in this patient group will likely be seen in other patient groups in the future. Ultimately, doctors and patients will lose treatment options and health care availability unless collaborative strategies are developed to reduce costs.

Effects of recombinant factor VIIa on platelet function and clot structure in blood with deficient prothrombin conversion

While recombinant factor VIIa (rFVIIa) shows promise as a broad-spectrum hemostatic agent, questions remain regarding the most appropriate dose and the best way to monitor its effects. In this study we tested the sensitivity of a thrombin dependent platelet assay, platelet contractile force, to the effects of rFVIIa in normal, factor-deficient, and inhibitor-containing blood samples. Dose dependent effects of rFVIIa on platelet contractile force (PCF) and clot elastic modulus (CEM) were measured in all blood samples.

rFVIIa minimally affected PCF and CEM in normal blood clotted with thrombin or batroxobin. While rFVIIa minimally altered PCF and CEM in factor VIII (FVIII) deficient blood clotted with thrombin, rFVIIa increased PCF and CEM and shortened the lag phase in a dose dependent manner in batroxobin-induced clots. The effects of rFVIIa in factor IX (FIX) deficient blood mirrored the effects seen in FVIII deficient samples. Whether clotted with thrombin or batroxobin, baseline PCF and CEM were abnormally low in FVIII deficient samples containing FVIII inhibitors. In such samples, rFVIIa caused dose dependent improvement of PCF, CEM, and lag phases. In one patient with a spontaneous inhibitor, rFVIIa caused dose dependent increases in PCF and CEM in blood clotted with either enzyme.

rFVIIa corrects the deficient thrombin generation seen in FVIII and FIX deficiency, and in blood containing FVIII inhibitors. As a consequence, platelet function is improved and clot structure is enhanced. Platelet contractile force and clot elastic modulus measurements are sensitive to the dose dependent effects of rFVIIa.

Haemostatic efficacy and safety of bolus and continuous infusion of recombinant factor VIIa are comparable in haemophilia patients with inhibitors undergoing major surgery

Bolus infusion (BI) recombinant factor VIIa (rFVIIa) administration is safe and effective in the surgical management of haemophilia patients with inhibitors but has not been compared directly with continuous infusion (CI). We conducted an open-label, randomized, multicenter trial comparing the efficacy and safety of rFVIIa administered by BI or CI for the surgical management of haemophilia A or B patients with inhibitors to FVIII or FIX. Safety was compared with that of a control group of noninhibitor patients receiving FVIII or FIX concentrates for major surgery. All inhibitor subjects received an initial bolus dose of 90 μg/kg rFVIIa and were then randomly assigned to BI (n=12) or CI (n=12). The BI group received 90 μg/kg rFVIIa every two hours (h) during surgery through day 5, then every four hours for days 6–10. The CI group received 50 μg/kg/h rFVIIa through day 5, then 25 mg/kg/h for days 6–10. The control group (n=12) received FVIII or FIX per institutional protocols. Twenty-two major surgeries included orthopedic procedures on the knee (n=13), hip (n=3), and abdominal/pelvis procedures (n=4). One patient with an autoimmune FVIII inhibitor randomized to the BI arm was excluded from efficacy analysis. Haemostatic efficacy of rFVIIa in each group was comparable: effective in 8/11 and 9/12 subjects in the BI and CI arms, respectively, and ineffective in three subjects in each arm. Serious adverse events were related to continued or increased bleeding. In conclusion, haemostatic efficacy and safety of BI and CI of rFVIIa are comparable for the surgical management of haemophilia subjects with inhibitors.

Major and Minor Classifications for Surgery in People With Hemophilia: A Literature Review

Agents that control bleeding and the usage of bypassing agents have made surgery an option to consider in people with hemophilia. However, the lack of consistent definitions for major or minor surgery may lead to inconsistencies in patient management. This literature review has evaluated how surgical procedures in people with hemophilia were categorized as major or minor surgery and assessed the consistency across publications. After screening 926 potentially relevant articles, 547 were excluded and 379 full-text articles were reviewed. Ninety-five articles categorized major or minor surgical procedures; of these, 35 publications categorized three or more major or minor surgical procedures and were included for analysis. Seven (20%) publications provided varying criteria for defining major or minor surgery, five of which defined surgery according to the level of surgical invasiveness. Across all 35 publications, there was considerable variance in the categorization of major and minor surgical procedures and some overlap in surgical nomenclature (eg, type of synovectomy, arthroscopy, and central venous access device insertion/removals). The lack of consistent guidance when referring to major or minor surgery in people with hemophilia needs to be addressed. Clear and consistent definitions, achieved by consensus and promoted by relevant international hemophilia committees, are desirable, to provide guidance on appropriate treatment, to increase the accuracy of trial data and may confound the interpretation of surgical outcomes.

Results from a large multinational clinical trial (guardian™3) using prophylactic treatment with turoctocog alfa in paediatric patients with severe haemophilia A: safety, efficacy and pharmacokinetics

Recombinant factor VIII (rFVIII) products provide a safe and efficacious replacement therapy for prophylaxis and treatment of bleeding episodes in patients with severe haemophilia A. This multinational, open-label, non-controlled trial investigated the safety, efficacy and pharmacokinetics (PK) of turoctocog alfa, a new rFVIII product, in a paediatric population. The primary objective was to evaluate safety. A total of 31 younger children (0-5 years) and 32 older children (6-11 years), with ≥ 50 exposure days to any factor VIII (FVIII) product and no history of inhibitors, received prophylaxis with turoctocog alfa (25-50 IU kg(-1) every second day or 25-60 IU kg(-1) three times weekly). PK assessments of turoctocog alfa and the patients' previous FVIII product were performed in 28 patients. Mean exposure to turoctocog alfa was 60 exposure days per patient. This corresponds to approximately 4.5 months in the trial. None of the patients developed inhibitors (≥ 0.6 BU) and no safety concerns were raised. A total of 120 bleeding episodes (95%) were controlled with 1-2 infusions of turoctocog alfa. Based on patient reports, the success rate (defined as 'excellent' or 'good' haemostatic response) for treatment of bleeding episodes was 92%. Overall, the median annualized bleeding rate was 3.0 (interquartile range: 8.5) bleeds patient(-1) year(-1) . PK parameters were comparable between the two age groups. In conclusion, the present large global clinical trial showed that turoctocog alfa was safe, effective in treatment of bleeding episodes and had a prophylactic effect in paediatric patients.

Results from a large multinational clinical trial (guardian™1) using prophylactic treatment with turoctocog alfa in adolescent and adult patients with severe haemophilia A: safety and efficacy

Recombinant factor VIII (rFVIII) products provide a safe and efficacious replacement therapy for prophylaxis and treatment of bleeding episodes in patients with severe haemophilia A. This multinational, open-label, non-controlled trial investigated the safety and efficacy of turoctocog alfa, a new rFVIII product. The primary objective was to evaluate safety. A total of 150 patients (24 adolescents and 126 adults) with severe haemophilia A (FVIII activity ≤ 1%), with at least 150 exposure days (EDs) to any FVIII product and no history of inhibitors were enrolled, and 146 patients (97%) completed the trial. All patients received prophylaxis with turoctocog alfa for approximately 6 months and had a mean of 85 EDs during the trial. None of the patients developed FVIII inhibitors, there were no indications of early FVIII inhibitor development and no safety concerns were identified. A total of 225 adverse events were reported in 100 (67%) patients, with the most common being events associated with dosing procedures, headaches, and nasopharyngitis. A total of 499 bleeding episodes were reported during the trial, the majority (89%) were controlled with 1-2 infusions of turoctocog alfa. Based on patient reports, the success rate (defined as 'excellent' or 'good' haemostatic response) for treatment of bleeding episodes was 81%. The overall median annualized bleeding rate was 3.7 (interquartile range: 8.7) bleeds/patient/year. In conclusion, turoctocog alfa provides a new, safe and effective alternative for prophylaxis and treatment of bleeding episodes in patients with haemophilia A.

Challenges of defining reliable clinical surrogate end points in haemophilia trials: a critical review

The success of a treatment in haemophilia patients experiencing a bleeding episode is very difficult to define. A variety of efficacy assessment tools have been developed in an effort to better assess when haemostasis has been achieved. These assessment tools are particularly important for the evaluation of the efficacy of therapeutic agents whose mechanism of action is based on pharmacological activity in haemostasis rather than upon the principle of 'replacement therapy'. This review focuses on a number of efficacy measures, summarizing their methodology and discussing their validity. In addition, future developments and requirements in order to evaluate the effectiveness of haemostatic treatment are discussed. The majority of end points used for evaluation of haemostasis relate to the relief of symptoms arising from bleeds. The results of this review highlight that several efficacy end points are frequently combined in order to provide a more comprehensive assessment of efficacy. Key limitations of current methodology are the subjectivity of assessment by either the patient or clinician, and the incomparability of results between trials.

Evidence-based use of recombinant FVIIa (NovoSeven, NiaStase) for the treatment of hemophilia with inhibitors in children and adolescents

Children and adolescents comprise a significant proportion of the hemophilia population, including those patients who have developed inhibitors to factor VIII or FIX. We examine the use of rFVIIa for the treatment of bleeding episodes and the prevention of bleeding in children and adolescents with hemophilia A and B with inhibitors, focusing on registry data and recent clinical trial results. Based on this review of the literature, we conclude that recombinant FVIIa is safe and effective for use in controlling bleeding in these patient populations.

Haemostatic efficacy and safety of bolus and continuous infusion of recombinant factor VIIa are comparable in haemophilia patients with inhibitors undergoing major surgery. Results from an open-label, randomized, multicenter trial

Bolus infusion (BI) recombinant factor VIIa (rFVIIa) administration is safe and effective in the surgical management of haemophilia patients with inhibitors but has not been compared directly with continuous infusion (CI). We conducted an open-label, randomized, multicenter trial comparing the efficacy and safety of rFVIIa administered by BI or CI for the surgical management of haemophilia A or B patients with inhibitors to FVIII or FIX. Safety was compared with that of a control group of non-inhibitor patients receiving FVIII or FIX concentrates for major surgery. All inhibitor subjects received an initial bolus dose of 90 microg/kg rFVIIa and were then randomly assigned to BI (n = 12) or CI (n = 12). The BI group received 90 microg/kg rFVIIa every two hours (h) during surgery through day 5, then every four hours for days 6-10. The CI group received 50 microg/kg/h rFVIIa through day 5, then 25 mg/kg/h for days 6-10. The control group (n = 12) received FVIII or FIX per institutional protocols. Twenty-two major surgeries included orthopedic procedures on the knee (n = 13), hip (n = 3), and abdominal/pelvis procedures (n = 4). One patient with an autoimmune FVIII inhibitor randomized to the BI arm was excluded from efficacy analysis. Haemostatic efficacy of rFVIIa in each group was comparable: effective in 8/11 and 9/12 subjects in the BI and CI arms, respectively, and ineffective in three subjects in each arm. Serious adverse events were related to continued or increased bleeding. In conclusion, haemostatic efficacy and safety of BI and CI of rFVIIa are comparable for the surgical management of haemophilia subjects with inhibitors.

Treatment of acquired haemophilia with recombinant activated FVII: a critical appraisal

Acquired haemophilia is a rare bleeding disorder usually caused by the spontaneous formation of inhibitory antibodies to coagulation FVIII. The disease occurs most commonly in the elderly, and although acquired haemophilia may be associated with a variety of underlying conditions, up to 50% of reported cases are idiopathic. Treatment options have traditionally involved human FVIII or FIX replacement therapy (if the inhibitor titre allows), porcine FVIII or the use of activated pro-thrombin complex concentrates. Recombinant activated coagulation FVII (rFVIIa) was available on an emergency and compassionate use basis from 1988 to 1999 at sites in Europe and North America. It has been registered in Europe for use in treating acquired haemophilia since 1996 and has recently been licensed for this indication in the United States. By directly activating FX on the surface of activated platelets at the site of injury (thereby bypassing FVIII and FIX), rFVIIa can circumvent the actions of inhibitory antibodies present in acquired haemophilia patients. This paper provides an overview of experiences with rFVIIa for the treatment of acquired haemophilia from the NovoSeven compassionate and emergency use programmes (1989-1999), the Hemophilia and Thrombosis Research Society Registry, and independent published reports from January 1999 to September 2005. rFVIIa has been reported to provide safe and effective haemostasis as a first line therapy in patients of all ages for a variety of surgical and non-surgical bleeding situations.

Recombinant activated Factor VII in major surgery and trauma patients: a response

The review article by Wilson et al. (Expert Opin. Drug Saf., 2005) on recombinant activated Factor VII (rFVIIa) offers some valuable insights into the ongoing exploration of this agent in the management of uncontrolled bleeding--an area of high unmet clinical need. This editorial highlights that the chosen citation of Riou et al. (Shock, 2004), in reference to two parallel studies conducted in trauma patients with blunt and penetrating injury, was both a report of an early analysis of the data, and was only one of several abstracts on these studies published in 2004. The authors of this editorial believe that the inclusion of the other published abstracts in this series would have provided a more comprehensive and balanced overview of recombinant activated Factor VII.

Dose optimization of recombinant factor VIIa in the treatment of acute bleeding in haemophilia-associated inhibitors

Recombinant coagulation factor VIIa (rFVIIa; NovoSeven) represents an important advance in the therapy for haemophilia patients with inhibitors. Since licensure, the standard dosing has been perceived as 90-120 microg/kg every 2-3 h until cessation of bleeding. There has been an accumulation of anecdotal experience with the use of higher, less frequent dosing of rFVIIIa, and a controlled clinical trial is underway to assess the safety and efficacy of the current dosing recommendation and a single dose of 270 microg/kg. Furthermore, a post-licensure database is being analysed to evaluate the current dosing in acute bleeding episodes. Treatment, efficacy, and safety data from haemophilia patients with inhibitors treated with rFVIIa in a variety of contexts, including the on-demand treatment of acute bleeding, were entered into the registry. Data from patients treated with bolus infusion of rFVIIa were analysed and bleeding episodes were grouped according to total rFVIIa dose administered. Registry data suggest that rFVIIa is both safe and effective at doses > 200 microg/kg and that efficacy improves with increased dose. The database is currently being analysed to determine if increasing dose is associated with an elimination of the need for repeat dosing.

Human recombinant DNA-derived antihaemophilic factor (factor VIII) in the treatment of haemophilia A: conclusions of a 5-year study of home therapy. The KOGENATE Study Group

Fifty-eight previously treated haemophilic subjects were treated exclusively with the recombinant FVIII (rFVIII-KOGENATE) produced by Bayer Corporation (Berkeley, CA) in an international multicentre prospective study of more than 5 years duration. Fifty-four of the 58 had severe haemophilia (< 2% FVIII) and four had moderate haemophilia (2-5% FVIII); 23/58 (40%) were seropositive for HIV, while 35/58 (60%) were HIV seronegative. Patients were monitored for safety and efficacy over a median period of 4.7 years (range 0.9-5.9 years) and received 17 922 infusions totalling 25.7 million units of rFVIII. Of 7107 bleeding episodes reported in home diaries, 5831 (82%) required only one treatment with rVIII. Twenty-five invasive surgical procedures in 17 patients, including eight joint replacements, were successfully accomplished and 13 serious bleeding episodes in eight patients were successfully treated. FVIII recovery performed on 885 occasions using 39 different lots of rFVIII showed mean incremental recovery of 2.48% IU-1 kg-1 (+/- 0.64). Adverse events were associated with 42 infusions (0.2%); none caused discontinuation of therapy. Immunological parameters remained stable in HIV-seronegative subjects treated with rFVIII; a small decrease in CD4 counts was noted in HIV-seropositive individuals (mean - 37.2 cells mm-3 yr-1). No de novo formation of inhibitors to FVIII was noted; and no clinical allergic reactions occurred to murine or hamster proteins. These conclusions from the longest monitored safety study ever performed for a haemophilia treatment product (with more than 5 years of observation) confirm previous interim study reports that rFVIII is well tolerated over the long-term, has biological activity comparable to that of plasma-derived FVIII, and is safe and efficacious for the treatment of haemophilia A.

Breast health at midlife: guidelines for screening and patient evaluation

Breast cancer is the leading cause of death of American women aged 40 to 55. The fear that midlife women have of developing breast cancer must be considered as physicians discuss breast health with their patients. Identification of risk factors is important, although 70% of women diagnosed with breast cancer have no known risk factors. Screening mammograms can detect early lesions, but controversy exists over whether they reduce mortality in women younger than ago 50. The American Cancer Society and the National Cancer Institute recently changed their screening mammography recommendations for women aged 40 to 49. A breast self-exam can be performed using the circular or wedge techniques. If a mass is found, physicians can help alleviate a patient's anxiety by providing a diagnosis as quickly as possible.

Long term evaluation of septic arthritis in hemophilic patients

Before 1983, septic arthritis was rare in patients with hemophilia. With the advent of human immunodeficiency virus infection in the hemophilia population, many centers noted an increasing incidence of patients with septic arthritis. Fifteen septic joints in 10 patients with severe hemophilia were documented. Eight patients were human immunodeficiency virus positive, 1 was human immunodeficiency virus negative, and 1 was not tested. The diagnosis was delayed in 5 patients because the symptoms are similar to an acute hemarthrosis. An elevated temperature was common. The white blood cell count was elevated in only 1/3 of the infections, being modified by human immunodeficiency virus infection. Associated risk factors included infected angioaccess catheters (2), pneumonia (2), and generalized sepsis (1). All but 1 joint responded to appropriate antibiotics and either repeated aspiration or arthrotomy. However, 6 patients died of acquired immunodeficiency syndrome from 2 to 109 months after infection. Three patients are alive 29, 86, and 96 months, respectively, after infection.

Spurious fibrinogen levels secondary to pyroglobulinemia in Waldenström's macroglobulinemia

We report two cases of pyroglobulinemia detected in the course of routine determination of fibrinogen levels measured by the heat-precipitation method and that led to the diagnosis of Waldenström's macroglobulinemia. The incidence of pyroglobulinemia is briefly discussed, and the potential significance of this laboratory artifact is emphasized.

Internalization of human immunodeficiency virus type I and other retroviruses by megakaryocytes and platelets

Direct infection of megakaryocytes and platelets by human immunodeficiency virus type I (HIV-I) or other retroviruses has not been demonstrated. To determine whether this could occur, murine bone marrow was co-cultivated with the amphotropic retrovirus-producing cell line PA317-N2, and freshly isolated normal human bone marrow and platelets were co-cultivated with HIV-infected H9 cells. In each case, ultrastructural analyses showed viruses within megakaryocytes and platelets. In murine specimens, the uptake of retrovirus was avid at all stages of differentiation. In human specimens, viral uptake was less frequent. These results suggest that direct infection of megakaryocytes could play a role in the pathophysiology of HIV-associated disease. In addition, these observations suggest that cells of the megakaryocyte lineage could serve as target cells in gene transfer experiments using retroviral-based vectors.

Growth- and tumor-promoting effects of deregulated BCL2 in human B-lymphoblastoid cells

Human follicular B-cell lymphomas possess a t(14;18) that translocates a putative protooncogene, BCL2, into the immunoglobulin heavy chain locus. The normal BCL2 gene is quiescent in resting B cells, expressed in proliferating, but down-regulated in differentiated B cells. Inappropriately high levels of BCL2-immunoglobulin chimeric RNA are present in t(14;18) lymphomas for their mature B-cell stage. We examined the biologic effects of BCL2 deregulation in human B cells by introducing BCL2 into human B-lymphoblastoid cell lines (LCLs) with retroviral gene transfer. Although deregulated BCL2 expression as a single agent was not sufficient to confer tumorigenicity to LCLs, it consistently produced a 3- to 4-fold increment in LCL clonogenicity in soft agar. In addition, BCL2 deregulation complements the transforming effects of the MYC oncogene in LCLs. BCL2 augmented the clonogenicity of LCLs bearing exogenous MYC and increased the frequency and shortened the latency of tumor induction in immunodeficient mice. These results demonstrate a role for BCL2 as a protooncogene that affects B-cell growth and enhances B-cell neoplasia.

Monoclonal antibodies to the human CSF-1 receptor (c-fms proto-oncogene product) detect epitopes on normal mononuclear phagocytes and on human myeloid leukemic blast cells

The first monoclonal antibodies (MoAbs) to epitopes in the extracellular domain of the human c-fms proto-oncogene product (receptor for the macrophage colony stimulating factor, CSF-1) were used with flow cytometric techniques to study receptor expression on normal human peripheral blood monocytes, bone marrow cells, and leukemic blasts. On normal cells CSF-1 receptors were restricted in their expression to cells of the mononuclear phagocyte lineage. CSF-1 receptors were detected on leukemic blasts from 15 (30%) of 50 children with acute myeloid leukemia, compared with four (15%) of 26 adults. By contrast, detectable CSF-1 receptors were uniformly absent on blasts from 19 children with acute lymphoblastic leukemia. CSF-1 receptors on normal monocytes and myeloid leukemia cells could be induced to downmodulate by incubation with either human recombinant CSF-1 or phorbol esters, confirming that the receptors had functional ligand-binding sites and responded to transmodulation by inducers of protein kinase C. The numbers of receptors per cell and the percentage of positive cases were highest for leukemic blasts with cytochemical and morphological features of monocytes. However, CSF-1 receptors were also detected on a subset of leukemic blast cells with features of granulocytic differentiation (FAB subtypes M1 through M3). Southern blotting analyses of DNA from 47 cases of acute myeloid leukemia demonstrated no rearrangements within the 32 kb of genomic sequences that contain CSF-1 receptor coding exons or in the 50 kb upstream of the first coding exon. Analysis of the upstream region of the c-fms locus revealed that sequences representing the terminal 112 untranslated nucleotides of c-fms mRNA map 26 kb 5' to the first coding exon, suggesting that at least one c-fms promoter is separated from the receptor coding sequences by a very long intron. Whereas expression of the CSF-1 receptor in myeloid leukemic blasts is not restricted to cells with monocytic characteristics, the apparently aberrant pattern of receptor synthesis in a subset of cases with granulocytic features appears not to be due to chromosomal rearrangements within 50 kb upstream of sequences encoding the receptor.

Transformation and plasmacytoid differentiation of EBV-infected human B lymphoblasts by ras oncogenes

The biological effects of ras oncogene activation in B cells were studied by using amphotropic retroviral vectors to introduce H- or N-ras oncogenes into human B lymphoblasts immortalized by Epstein-Barr virus. Expression of both H- and N-ras oncogenes led to malignant transformation of these cells, as shown by clonogenicity in semisolid media and tumorigenicity in immunodeficient mice. In addition, terminal differentiation into plasma cells was detectable as specific changes in morphology, immunoglobulin secretion, and cell surface antigen expression. This combined effect, promoting growth and differentiation in human lymphoblasts, represents a novel biological action of ras oncogenes and has implications for the pathogenesis of terminally differentiated B-lymphoid malignancies such as multiple myeloma.

Diversity in inhibitory effects of IFN-gamma and IFN-alpha A on the induced DNA synthesis of a hairy cell leukemia B lymphocyte clone reflects the nature of the activating ligand

A hairy cell leukemia population was used as a clonal model for studying the direct immunomodulatory effects of recombinant interferon-alpha A (rIFN-alpha A) and rIFN-gamma on human B-cell proliferation. The leukemic cell population KON was notably quiescent when incubated in medium alone but was induced to significant in vitro DNA synthesis when cultured with any of four activators of human B cells: anti-IgM antibody, Staphylococcus aureus cells (SAC), phorbol myristate acetate (PMA), or B-cell growth factor (BCGF). While both rIFN-gamma and rIFN-alpha A exhibited suppressive effects on these responses, their inhibitory patterns were distinct and reciprocal. Thus, rIFN-gamma exclusively suppressed anti-IgM-and SAC-induced leukemic DNA synthesis, and rIFN-alpha A significantly suppressed only PMA- and BCGF-induced DNA synthesis. The effects of the rIFN preparations were ablated in the presence of IFN type-specific monoclonal antibodies. Kinetic analyses and pulsing studies revealed that inhibition was most notable when cells were exposed concomitantly to IFN and the activating ligand. That the diverse effects of IFN-gamma and IFN-alpha A are manifested on a single B-cell clone was confirmed by Southern blot analysis of restriction enzyme-digested KON cell DNA with a JH-specific probe. These studies suggest that the therapeutic potential of the two types of IFN may be influenced by the nature of the extracellular ligands in the leukemic mileau that promote leukemic clonal expansion.

Human leukemic B cell activation: functional consequence of membrane IgM interaction with anti-IgM ligand is an alterable cell characteristic

A functional study of several human malignant B cell populations has indicated that occasional leukemic clones are extraordinarily sensitive to signal transduction through membrane IgM. One isolated hairy cell leukemia (HCL) with low background DNA synthesis was stimulated to significant levels of DNA synthesis when cultured with high (100 micrograms/mL) concentrations of soluble anti-IgM ligands. In contrast to the activation of normal peripheral blood polyclonal B cells, this DNA synthesis was completely independent of accessory T cell factors. Although the HCL clone could also be induced to enter S phase by incubation in media supplemented with only activated T cell supernatant, culture of the clone with activated T cell supernatant plus anti-IgM Ab resulted in DNA synthesis that was significantly less than that induced by either activator alone. Factor(s) in T cell supernatant appear to modulate the leukemic clone so that the binding of ligand to membrane IgM is perceived as an inhibitory rather than a stimulatory signal for DNA synthesis. In terms of Ig Fc independence and low ligand dose requirements, anti-IgM-mediated inhibitory signal transduction in the T cell supernatant-activated HCL clone was found to mimic anti-IgM mediated suppression of the spontaneous DNA synthesis of an alternative HCL clone. The functional results suggest that the type of signal transduced anti-Ig ligands may reflect differences in the activation state of receptive leukemic B cells.

Trisomy 22--a new abnormality found in acute leukemia characterized by eosinophilia and monocytoid blasts expressing immature differentiation antigens

Bone marrow cells from three patients with acute myeloid leukemia, with marrow eosinophilia and monocytoid blasts, showed a new nonrandom chromosomal abnormality, trisomy 22. In two patients the classification of leukemia was M4 and in the third patient M2 (FAB classification). Pretreatment bone marrows in these patients revealed 31%, 30%, and 4% eosinophils, respectively. Blast cells isolated from peripheral blood were Ia-positive and expressed immature monocyte lineage antigens (U26, U28, U48) in 26%-92% of cells. All three patients had a population of bone marrow cells characterized by an extra chromosome #22. One patient also had inversion of chromosome #16. Trisomy 22, bone marrow eosinophilia, and monocytoid blasts displaying early monocyte differentiation antigens may represent a new subgroup of patients with acute myeloid leukemia.

Acute nonlymphocytic leukemia following gastric adenocarcinoma treated by surgery alone. Evidence for etiologic heterogeneity of "secondary" leukemias

The case of a 36-year-old Hispanic man who developed acute nonlymphocytic leukemia 18 months following gastric adenocarcinoma treated by surgery alone is presented. Cytogenetic analysis of the leukemic cells revealed numerical and structural chromosomal rearrangements including chromosomes 5 and 7 and immunologic characterization of the blasts revealed terminal deoxynucleotidyltransferase positivity with monocytoid features. This report suggests that not all cases of acute nonlymphocytic leukemia following chemotherapy and/or radiotherapy, which characteristically display similar cytogenetic and immunologic features, should be exclusively ascribed to the leukemogenic properties of anticancer treatment.

Definition of a possible genetic basis for susceptibility to acute myelogenous leukemia associated with the presence of a polymorphic Ia epitope

The polymorphic Ia epitope recognized by monoclonal antibody 109d6 is detectable on the leukemic cells of a significantly increased number of individuals with acute myelogenous leukemia, compared with its frequency in normal healthy control individuals. In control individuals, the presence of the 109d6 epitope is closely correlated with but not identical to the DRw53 allo-specificity. However, the frequency of particular conventional Ia allodeterminants, including DRw53, is not significantly elevated in the leukemia group. Considerable evidence supports the conclusion that the high frequency of the 109d6 epitope reflects an inherited basis for susceptibility to the development of acute myelogenous leukemia and not a differentiation event occurring in the leukemic lineage. The 109d6 determinant is expressed by leukemic myeloblasts as well as by homologous normal B cells and monocytes obtained from the same individuals during remission of the leukemia. Furthermore, in healthy family members the 109d6 epitope is encoded by Ia haplotypes that are shared with the patient. Of special interest, certain of these haplotypes have combinations of the 109d6 epitope and Ia specificities not commonly seen in normal individuals; here, also, healthy family members share these haplotypes.

Definition of AML susceptibility and classification using monoclonal antibodies

Of 112 patients with acute leukemia 13 exhibited terminal deoxyribonucleotidyl transferase activity (TdT) with a cell phenotype characterized by the presence of early or mature monocyte differentiation antigens detected by monoclonal antibodies and elevated serum lysozyme. These cells were either unclassifiable by cytochemical analysis or fell into the M2 or M5 categories by the French-American-British classification. These leukemias appear to form a distinct nosologic entity representing a malignant transformation among early cells in the monocyte lineage. Among 60 patients with acute myelogenous leukemia 87% expressed the polymorphic Ia antigen detected by monoclonal antibody 109d6 compared to an incidence of 40.5% in the control population, relative risk 9.2. Evidence was obtained that this antigen was present in healthy family members and remission B-cells and monocytes of patients, and that its presence was associated with a genetically defined susceptibility state for the development of acute myelogenous leukemia.

TdT-positive acute leukemia with monocytoid characteristics: clinical, cytochemical, cytogenetic, and immunologic findings

Thirteen patients with acute leukemias that were difficult to classify by the use of cytochemical staining and terminal deoxyribonucleotidyl transferase (TdT) activity are reported. The phenotype of the leukemic cells was characterized by the presence of mature or early monocyte lineage antigens and intense Ia antigen expression detected by monoclonal antibodies, terminal deoxytransferase activity, and cytochemical features, including both Sudan black B and periodic acid-Schiff activity. The mean age of this group of patients was 60 years. Five patients had leukemia occurring after chemotherapy or radiotherapy of a prior malignant disease, and two patients had a refractory anemia prior to development of acute leukemia. These patients had a low response rate to chemotherapy. This series of leukemia appears to form a distinct nosologic entity, representing a leukemic transformation among early cells of the monocyte lineage, resulting in a predominant neoplastic cell that is less mature than either the French-American-British M4 acute myelomonocytic leukemia or M5 acute monoblastic leukemia. The presence of terminal deoxytransferase activity was interpreted as indicating the primitive state of the cells in the differentiation sequence, rather than as implying any significance with respect to lineage.

Evidence for the separate molecular expression of four distinct polymorphic Ia epitopes on cells of DR4 homozygous individuals

The monoclonal antibodies 109d6 and IVD12 reacted with separate polymorphic Ia epitopes in immunofluorescent studies. Using a panel of lymphoblastoid B cell lines, antibody 109d6 reacted with all HLA-DR4 or DR7 positive lines in a pattern resembling the MT3 specificity recognized by human alloantisera. The antibody IVD12 reacted with all HLA-DR4 and two of three DR5 positive B cell lines suggesting that it recognized a specificity similar to MB3. The intensity of fluorescence was greater on DR5(+) cell lines than on DR4(+) cell lines relative to the amount of a nonpolymorphic Ia determinant. Among 45 unrelated control individuals reactivity with antibody 109d6 was correlated most closely with (r = 0.724) but not identical in occurrence to the MT3 specificity. Cocapping experiments demonstrated that the 109d6 epitope and the IVD12 epitope were present on independently redistributed cell surface molecules of DR4 homozygous lymphoblastoid cell lines. Furthermore, the DR4 alloantigens detected by an absorbed polyclonal human alloserum were similarly identified on molecules that were independent from those bearing either the 109d6 epitope or the IVD12 epitope. Taken together, these data indicate the existence of at least four distinct, serologically defined Ia molecular species.

The dental hygienist--a member of the team?

The importance and role of computed tomography (CT) are discussed on the basis of 36 cases of vertebral osteomyelitis. The bone images themselves, the detection of lumbar disk hypodensity, and the exploration of soft paraspinal regions in the search for an abscess are factors that contribute to the superiority of this method in difficult cases. In cases where the diagnosis is already known, CT offers an excellent method to assess the extent of the lesions. Its accuracy, coupled with its rapidity and noninvasive nature, affects the role of conventional tomography, a method that is incomplete and involves higher radiation doses. CT offers an excellent method for follow-up after treatment of vertebral osteomyelitis.