Abstract LB-272: KYM-001, a first-in-class oral IRAK4 protein degrader, induces tumor regression in xenograft models of MYD88-mutant ABC DLBCL alone and in combination with BTK inhibition

Purpose: This work assessed the antitumor activity of selective small molecule IRAK4 degraders in human ABC DLBCL cell lines in vitro and in tumor xenograft models in vivo, alone and in combination with BTK inhibition.

Introduction: ABC DLBCL comprises approximately 45% of DLBCL and has a worse outcome with R-CHOP chemotherapy compared to GCB DLBCL. Activating mutations in MYD88 occur in 30-40% of ABC DLBCL; L265P, the most prevalent MYD88 mutation, causes constitutive assembly and activation of the Myddosome. IRAK4 kinase and scaffolding functions are essential for full signaling through the Myddosome to NFκB and MAPK pathways. Kymera Therapeutics is using a chemical knockdown strategy to develop heterobifunctional small molecule IRAK4 degraders, exemplified by KYM-001, for the treatment of MYD88-driven lymphomas.

Methods: IRAK4 in human PBMC, ABC DLBCL cell lines and xenografts was quantified by immunoassays or targeted MS/MS. Myddosome signaling was monitored by mRNA and phosphoprotein endpoints. Cell viability and cell cycle were monitored by flow cytometry. Tumor xenograft studies were conducted by implanting human ABC DLBCL lines into immunocompromised mouse strains and assessing tumor volume.

Key data: KYM-001 led to potent E3 ligase-dependent degradation of IRAK4. Notably, KYM-001 more effectively inhibited TLR-activated Myddosome signaling compared to IRAK4 kinase inhibitors in human PBMC. Degradation was highly selective for IRAK4 vs >10,000 other detected proteins in the MYD88 L265P mutant ABC DLBCL line OCI-LY10. IRAK4 degradation by KYM-001 resulted in cell cycle inhibition and apoptosis within 48-72 h in ABC DLBCL, with preferential activity in MYD88-mutant vs MYD88-WT cell lines. Oral dosing of KYM-001 showed dose-dependent antitumor activity in several mouse xenograft models of human MYD88-mutant ABC DLBCL at tolerated doses and schedules. In the OCI-LY10 model, tumor regression was associated with >80% degradation of IRAK4, establishing the pharmacodynamic effect required for maximal efficacy. Since alterations in BCR signaling and MYD88 frequently co-occur in B-cell malignancies, we investigated the potential for combined activity of IRAK4 degradation and BTK inhibition. In the OCI-LY10 xenograft model, which has activating mutations in both CD79B and MYD88, BTK inhibition with ibrutinib had an additive effect on KYM-001 antitumor activity.

Conclusions: KYM-001 is a first-in-class, potent, selective and orally active IRAK4 degrader that causes tumor regression in ABC-DLBCL models. Degradation of IRAK4 removes both the kinase and scaffolding functions of IRAK4, and may be superior to kinase inhibition alone. These data support IRAK4 degraders as a promising new therapeutic opportunity for MYD88-driven lymphoma, both alone and in combination with other targeted approaches such as BTK inhibition.

Citation Format: Joseph F. Kelleher, Veronica Campbell, Jesse Chen, Jared Gollob, Nan Ji, Hari Kamadurai, Christine Klaus, Henry Li, Christine Loh, Alice McDonald, Haojing Rong, Scott Rusin, Kirti Sharma, Dominico Vigil, Duncan Walker, Matt Weiss, Karen Yuan, Yi Zhang, Laurent Audoly, Nello Mainolfi. KYM-001, a first-in-class oral IRAK4 protein degrader, induces tumor regression in xenograft models of MYD88-mutant ABC DLBCL alone and in combination with BTK inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-272.

A comparative study between hot-melt extrusion and spray-drying for the manufacture of anti-hypertension compatible monolithic fixed-dose combination products

The purpose of this work was to investigate the application of different advanced continuous processing techniques (hot melt extrusion and spray drying) to the production of fixed-dose combination (FDC) monolithic systems comprising of hydrochlorothiazide and ramipril for the treatment of hypertension. Identical FDC formulations were manufactured by the two different methods and were characterised using powder X-ray diffraction (PXRD) and modulated differential scanning calorimetry (mDSC). Drug dissolution rates were investigated using a Wood's apparatus, while physical stability was assessed on storage under controlled temperature and humidity conditions. Interestingly both drugs were transformed into their amorphous forms when spray dried, however, hydrochlorothiazide was determined, by PXRD, to be partially crystalline when hot melt extruded with either polymer carrier (Kollidon® VA 64 or Soluplus®). Hot melt extrusion was found to result in significant degradation of ramipril, however, this could be mitigated by the inclusion of the plasticizer, polyethylene glycol 3350, in the formulation and appropriate adjustment of processing temperature. The results of intrinsic dissolution rate studies showed that hot-melt extruded samples were found to release both drugs faster than identical formulations produced via spray drying. However, the differences were attributable to the surface roughness of the compressed discs in the Wood's apparatus, rather than solid state differences between samples. After a 60-day stability study spray dried samples exhibited a greater physical stability than the equivalent hot melt extruded samples.

Sample environment for neutron scattering measurements of internal stresses in engineering materials in the temperature range of 6 K to 300 K

Internal stresses in materials have a considerable effect on material properties including strength, fracture toughness, and fatigue resistance. The ENGIN-X beamline is an engineering science facility at ISIS optimized for the measurement of strain and stress using the atomic lattice planes as a strain gauge. Nowadays, the rapidly rising interest in the mechanical properties of engineering materials at low temperatures has been stimulated by the dynamic development of the cryogenic industry and the advanced applications of the superconductor technology. Here we present the design and discuss the test results of a new cryogenic sample environment system for neutron scattering measurements of internal stresses in engineering materials under a load of up to 100 kN and in the temperature range of 6 K to 300 K. Complete cooling of the system starting from the room temperature down to the base temperature takes around 90 min. Understanding of internal stresses in engineering materials at cryogenic temperatures is vital for the modelling and designing of cutting-edge superconducting magnets and other superconductor based applications.

RAS/MAPK Activation Drives Resistance to Smo Inhibition, Metastasis, and Tumor Evolution in Shh Pathway-Dependent Tumors

Aberrant Shh signaling promotes tumor growth in diverse cancers. The importance of Shh signaling is particularly evident in medulloblastoma and basal cell carcinoma (BCC), where inhibitors targeting the Shh pathway component Smoothened (Smo) show great therapeutic promise. However, the emergence of drug resistance limits long-term efficacy, and the mechanisms of resistance remain poorly understood. Using new medulloblastoma models, we identify two distinct paradigms of resistance to Smo inhibition. Sufu mutations lead to maintenance of the Shh pathway in the presence of Smo inhibitors. Alternatively activation of the RAS-MAPK pathway circumvents Shh pathway dependency, drives tumor growth, and enhances metastatic behavior. Strikingly, in BCC patients treated with Smo inhibitor, squamous cell cancers with RAS/MAPK activation emerged from the antecedent BCC tumors. Together, these findings reveal a critical role of the RAS-MAPK pathway in drug resistance and tumor evolution of Shh pathway-dependent tumors.

Coordinate activation of Shh and PI3K signaling in PTEN-deficient glioblastoma: new therapeutic opportunities

In glioblastoma, phosphatidylinositol 3-kinase (PI3K) signaling is frequently activated by loss of the tumor suppressor phosphatase and tensin homolog (PTEN). However, it is not known whether inhibiting PI3K represents a selective and effective approach for treatment. We interrogated large databases and found that sonic hedgehog (SHH) signaling is activated in PTEN-deficient glioblastoma. We demonstrate that the SHH and PI3K pathways synergize to promote tumor growth and viability in human PTEN-deficient glioblastomas. A combination of PI3K and SHH signaling inhibitors not only suppressed the activation of both pathways but also abrogated S6 kinase (S6K) signaling. Accordingly, targeting both pathways simultaneously resulted in mitotic catastrophe and tumor apoptosis and markedly reduced the growth of PTEN-deficient glioblastomas in vitro and in vivo. The drugs tested here appear to be safe in humans; therefore, this combination may provide a new targeted treatment for glioblastoma.

Interfering with resistance to smoothened antagonists by inhibition of the PI3K pathway in medulloblastoma

The malignant brain cancer medulloblastoma is characterized by mutations in Hedgehog (Hh) signaling pathway genes, which lead to constitutive activation of the G protein (heterotrimeric guanosine triphosphate-binding protein)-coupled receptor Smoothened (Smo). The Smo antagonist NVP-LDE225 inhibits Hh signaling and induces tumor regression in animal models of medulloblastoma. However, evidence of resistance was observed during the course of treatment. Molecular analysis of resistant tumors revealed several resistance mechanisms. We noted chromosomal amplification of Gli2, a downstream effector of Hh signaling, and, more rarely, point mutations in Smo that led to reactivated Hh signaling and restored tumor growth. Analysis of pathway gene expression signatures also, unexpectedly, identified up-regulation of phosphatidylinositol 3-kinase (PI3K) signaling in resistant tumors as another potential mechanism of resistance. Probing the relevance of increased PI3K signaling, we demonstrated that addition of the PI3K inhibitor NVP-BKM120 or the dual PI3K-mTOR (mammalian target of rapamycin) inhibitor NVP-BEZ235 to the initial treatment with the Smo antagonist markedly delayed the development of resistance. Our findings may be useful in informing treatment strategies for medulloblastoma.

Loss of the tumor suppressor Snf5 leads to aberrant activation of the Hedgehog-Gli pathway

Aberrant activation of the Hedgehog (Hh) pathway can drive tumorigenesis. To investigate the mechanism by which glioma-associated oncogene family zinc finger-1 (GLI1), a crucial effector of Hh signaling, regulates Hh pathway activation, we searched for GLI1-interacting proteins. We report that the chromatin remodeling protein SNF5 (encoded by SMARCB1, hereafter called SNF5), which is inactivated in human malignant rhabdoid tumors (MRTs), interacts with GLI1. We show that Snf5 localizes to Gli1-regulated promoters and that loss of Snf5 leads to activation of the Hh-Gli pathway. Conversely, re-expression of SNF5 in MRT cells represses GLI1. Consistent with this, we show the presence of a Hh-Gli-activated gene expression profile in primary MRTs and show that GLI1 drives the growth of SNF5-deficient MRT cells in vitro and in vivo. Therefore, our studies reveal that SNF5 is a key mediator of Hh signaling and that aberrant activation of GLI1 is a previously undescribed targetable mechanism contributing to the growth of MRT cells.

Discovery of NVP-LDE225, a Potent and Selective Smoothened Antagonist

The blockade of aberrant hedgehog (Hh) signaling has shown promise for therapeutic intervention in cancer. A cell-based phenotypic high-throughput screen was performed, and the lead structure (1) was identified as an inhibitor of the Hh pathway via antagonism of the Smoothened receptor (Smo). Structure-activity relationship studies led to the discovery of a potent and specific Smoothened antagonist N-(6-((2S,6R)-2,6-dimethylmorpholino)pyridin-3-yl)-2-methyl-4'-(trifluoromethoxy)biphenyl-3-carboxamide (5m, NVP-LDE225), which is currently in clinical development.

1-amino-4-benzylphthalazines as orally bioavailable smoothened antagonists with antitumor activity

Abnormal activation of the Hedgehog (Hh) signaling pathway has been linked to several types of human cancers, and the development of small-molecule inhibitors of this pathway represents a promising route toward novel anticancer therapeutics. A cell-based screen performed in our laboratories identified a new class of Hh pathway inhibitors, 1-amino-4-benzylphthalazines, that act via antagonism of the Smoothened receptor. A variety of analogues were synthesized and their structure-activity relationships determined. This optimization resulted in the discovery of high affinity Smoothened antagonists, one of which was further profiled in vivo. This compound displayed a good pharmacokinetic profile and also afforded tumor regression in a genetic mouse model of medulloblastoma.

Identification and structure-activity relationships of ortho-biphenyl carboxamides as potent Smoothened antagonists inhibiting the Hedgehog signaling pathway

Ortho-biphenyl carboxamides, originally prepared as inhibitors of microsomal triglyceride transfer protein (MTP) have been identified as novel inhibitors of the Hedgehog signaling pathway. Structure-activity relationship studies for this class of compounds reduced MTP inhibitory activity and led to low nanomolar Hedgehog inhibitors. Binding assays revealed that the compounds act as antagonists of Smoothened and show cross-reactivity for both the human and mouse receptor.

Essential role of stromally induced hedgehog signaling in B-cell malignancies

Interaction of cancer cells with their microenvironment generated by stromal cells is essential for tumor cell survival and influences the localization of tumor growth. Here we demonstrate that hedgehog ligands secreted by bone-marrow, nodal and splenic stromal cells function as survival factors for malignant lymphoma and plasmacytoma cells derived from transgenic Emu-Myc mice or isolated from humans with these malignancies. Hedgehog pathway inhibition in lymphomas induced apoptosis through downregulation of Bcl2, but was independent of p53 or Bmi1 expression. Blockage of hedgehog signaling in vivo inhibited expansion of mouse lymphoma cells in a syngeneic mouse model and reduced tumor mass in mice with fully developed disease. Our data indicate that stromally induced hedgehog signaling may provide an important survival signal for B- and plasma-cell malignancies in vitro and in vivo. Disruption of this interaction by hedgehog pathway inhibition could provide a new strategy in lymphoma and multiple myeloma therapy.

Actin' like actin?

The most biologically significant property of actin is its ability to self-associate and form two-stranded polymeric microfilaments. In living cells, these micro filaments form the actin cytoskeleton, essential for maintenance of the shape, passive mechanical properties and active motility of eukaryotic cells. Recently discovered actin-related proteins (ARPs) appear to share a common ancestor with conventional actin. At present, six classes of ARPs have been discovered, three of which have representatives in diverse species across eukaryotic phyla and may share functional characteristics with conventional actin. The three most ubiquitous ARPs are predicted to share a common core structure with actin and contain all the residues required for ATP binding. Surface residues involved in protein protein interactions, however, have diverged. Models of these proteins based on the atomic structure of actin provide some clues about how ARPs interact with each other, with conventional actin and with conventional actin-binding proteins.

Bilateral breast relapse in acute myelogenous leukemia

We present the case of an 11.5-year-old girl with M1 acute myelogenous leukemia (AML) who had isolated extramedullary relapse develop in both breasts 12 months after diagnosis and 7 months off chemotherapy. She received further chemotherapy, focal radiation therapy, then underwent a matched, unrelated bone marrow transplant and continues in remission 37 months later. Review of the literature revealed 10 cases in other children younger than 21-years-old with AML and breast involvement. These cases are summarized, and potential pathophysiologic mechanisms of spread are discussed. Breast involvement in AML is rare in children. However, regular breast examinations should be performed as part of routine follow-up in all girls with AML.

Hepatic dysfunction as the presenting feature of acute lymphoblastic leukemia

PURPOSE

Hepatic dysfunction is a rare presentation of leukemia in children. Because most chemotherapy agents are metabolized by the liver, this complication may have major adverse consequences and effective treatment could be compromised.

PATIENTS AND METHODS

The MEDLINE database and current management guidelines from the United States Pediatric Cooperative Cancer Groups were reviewed and analyzed. Data from two institutional cases are described.

RESULTS

Although previous literature is not informative, our experience suggests that children with leukemia and moderate hepatic dysfunction may tolerate aggressive chemotherapy.

CONCLUSION

Current protocol guidelines for dose modification for liver disease may be overly stringent and modification may be beneficial.

Successful treatment of disseminated relapsed medulloblastoma in an infant by primary radiotherapy

An infant who experienced disseminated relapse of medulloblastoma while receiving chemotherapy is described. He was subsequently treated with radiation therapy. Seven and one-half years from diagnosis, he is currently disease-free and enjoys a relatively normal life. We emphasize the importance of considering radiation as one of the treatment modalities for young children with relapsed medulloblastoma.

Myosin VI is required for asymmetric segregation of cellular components during C. elegans spermatogenesis

BACKGROUND

The asymmetric division of cells and unequal allocation of cell contents is essential for correct development. This process of active segregation is poorly understood but in many instances has been shown to depend on the cytoskeleton. Motor proteins moving along actin filaments and microtubules are logical candidates to provide the motive force for asymmetric sorting of cell contents. The role of myosins in such processes has been suggested, but few examples of their involvement are known.

RESULTS

Analysis of a Caenorhabditis elegans class VI myosin deletion mutant reveals a role for this motor protein in the segregation of cell components during spermatogenesis. Mutant spermatocytes cannot efficiently deliver mitochondria and endoplasmic reticulum/Golgi-derived fibrous-body membranous organelle complexes to budding spermatids, and fail to remove actin filaments and microtubules from the spermatids. The segregation defects are not due to a global sorting failure as nuclear inheritance is unaffected.

CONCLUSIONS

C. elegans myosin VI has an important role in the unequal partitioning of both organelles and cytoskeletal components, a novel role for this class of motor protein.

Intracellular motility: how can we all work together?

Recent results reinforce the view that actin-based and microtubule-based motility systems do not operate independently, but are used in coordinated fashion to determine intracellular localization of cargo such as organelles.

Arp2/3 complex from Acanthamoeba binds profilin and cross-links actin filaments

The Arp2/3 complex was first purified from Acanthamoeba castellanii by profilin affinity chromatography. The mechanism of interaction with profilin was unknown but was hypothesized to be mediated by either Arp2 or Arp3. Here we show that the Arp2 subunit of the complex can be chemically cross-linked to the actin-binding site of profilin. By analytical ultracentrifugation, rhodamine-labeled profilin binds Arp2/3 complex with a Kd of 7 microM, an affinity intermediate between the low affinity of profilin for barbed ends of actin filaments and its high affinity for actin monomers. These data suggest the barbed end of Arp2 is exposed, but Arp2 and Arp3 are not packed together in the complex exactly like two actin monomers in a filament. Arp2/3 complex also cross-links actin filaments into small bundles and isotropic networks, which are mechanically stiffer than solutions of actin filaments alone. Arp2/3 complex is concentrated at the leading edge of motile Acanthamoeba, and its localization is distinct from that of alpha-actinin, another filament cross-linking protein. Based on localization and actin filament nucleation and cross-linking activities, we propose a role for Arp2/3 in determining the structure of the actin filament network at the leading edge of motile cells.

Phase I/II study of idarubicin given with continuous infusion fludarabine followed by continuous infusion cytarabine in children with acute leukemia: a report from the Children's Cancer Group

PURPOSE

The Children's Cancer Group (CCG) undertook a phase I study (CCG-0922) to determine a tolerable dose of idarubicin given with fludarabine and cytarabine in children with relapsed or refractory leukemia. The phase I study was extended to a limited phase II study to assess the activity of this combination in children with acute myelogenous leukemia (AML).

PATIENTS AND METHODS

This was a multiinstitutional study within the CCG. Eleven patients were entered onto the phase I study: seven with AML, three with acute lymphoblastic leukemia (ALL), and one with chronic myelogenous leukemia (CML). The maximal-tolerated dose (MTD) of fludarabine and cytarabine determined in a previous study was a fludarabine loading dose (LD) of 10.5 mg/m2 followed by a continuous infusion (CI) of 30.5 mg/m2/24 hours for 48 hours, followed by cytarabine LD 390 mg/m2, then CI 101 mg/m2/h for 72 hours. Idarubicin was given at three dose levels: 6, 9, and 12 mg/m2 intravenously (I.V.) on days 0, 1, and 2. The phase II portion of the trial included 10 additional patients with relapsed or refractory AML.

RESULTS

A dose of idarubicin 12 mg/m2/d for 3 days given in combination with fludarabine and cytarabine was tolerated. The major toxicity encountered was hematologic. Nonhematologic toxicities included transaminase elevations, hyperbilirubinemia, and infections. Eight of 10 patients with AML in the phase II portion (12 mg/m2 idarubicin) achieved a complete remission (CR).

CONCLUSION

This combination is active in patients with relapsed or refractory AML. The major toxicity encountered is hematologic. This regimen may be useful therapy for AML and should be compared with standard induction therapy in children with newly diagnosed AML.

Desmoplastic small round-cell tumor: prolonged progression-free survival with aggressive multimodality therapy

PURPOSE

To test intensive alkylator-based therapy in desmoplastic small round-cell tumor (DSRCT).

PATIENTS AND METHODS

Patients received the P6 protocol, which has seven courses of chemotherapy. Courses 1, 2, 3, and 6 included cyclophosphamide 4,200 mg/m2, doxorubicin 75 mg/m2, and vincristine (HD-CAV). Courses 4, 5, and 7 consisted of ifosfamide 9 g/m2 and etoposide 500 mg/m2 for previously untreated patients, or ifosfamide 12 g/m2 and etoposide 1,000 mg/m2 for previously treated patients. Courses started after neutrophil counts reached 500/microL and platelet counts reached 100,000/microL. Tumor resection was attempted. Post-P6 treatment options included radiotherapy and a myeloablative regimen of thiotepa (900 mg/m2) plus carboplatin (1,500 mg/m2), with stem-cell rescue.

RESULTS

Ten previously untreated and two previously treated patients have completed therapy. The male-to-female ratio was 11:1. Ages were 7 to 22 years (median, 14). The largest masses were infradiaphragmatic (n = 11) or intrathoracic (n = 1). Other findings included serosal implants (n = 11), regional lymph node invasion (n = 8), ascites or pleural effusion (n = 7), and metastases to liver (n = 5), lungs (n = 4), distant lymph nodes (n = 3), spleen (n = 2), and skeleton (n = 2). Tumors uniformly responded to HD-CAV, but there were no complete pathologic responses. One patient died at 1 month from tumor-related Budd-Chiari syndrome. Of seven patients who achieved a complete remission (CR), five remain in CR 9, 12, 13, 33, and 38 months from the start of P6, one patient died of infection at 12 months (autopsy-confirmed CR), and one patient relapsed 4 months off therapy. Of four patients who achieved a partial remission (PR), one remains progression-free at 34 months and three developed progressive disease. Five patients received local radiotherapy: three were not assessable for response, but in two patients, antitumor effect was evident. Four patients received thiotepa/carboplatin: two were in CR and remain so, and two patients had measurable disease that did not respond.

CONCLUSION

For control of DSRCT, our experience supports intensive use of HD-CAV, aggressive surgery to resect visible disease, radiotherapy to high-risk sites, and myeloablative chemotherapy with stem-cell rescue in selected cases.

Sequences, structural models, and cellular localization of the actin-related proteins Arp2 and Arp3 from Acanthamoeba

We cloned and sequenced the two actin-related proteins (Arps) present in the profilin-binding complex of Acanthamoeba (Machesky, L. M., S. J. Atkinson, C. Ampe, J. Vandekerckhove, and T. D. Pollard. 1994, J. Cell Biol. 127:107-115). The sequence of Arp2 is more similar to other Arp2s than to actin, while the sequence of Arp3 is more similar to other Arp3s than to actin. Phylogenetic analysis of all known Arps demonstrates that most group into three major families, which are likely to be shared across all eukaryotic phyla. Together with conventional actins, the Arps form a larger family distinct from structurally related ATPases such as Hsp70's and sugar kinases. Atomic models of the Arps based on their sequences and the structure of actin provide some clues about function. Both Arps have atoms appropriately placed to bind ATP and divalent cation. Arp2, but not Arp3, has a conserved profilin-binding site. Neither Arp has the residues required to copolymerize with actin, but an Arp heterodimer present in the profilin-binding complex might serve as a pointed end nucleus for actin polymerization. Both Acanthamoeba Arps are soluble in cell homogenates, and both are concentrated in the cortex of Acanthamoeba. The cellular concentrations are 1.9 microM Arp2 and 5.1 microM Arp3, substoichiometric to actin (200 microM) but comparable to many actin-binding proteins.

Prevalence of antibodies to hepatitis C virus in transfused children with cancer

PURPOSE

Hepatitis C virus (HCV) transmission is a well-documented complication of blood transfusions, although data on transfused children with cancer is sparse. Using a newer assay for anti-HCV antibodies, the prevalence of HCV infection was determined in a population of children with cancer in the United States.

PATIENTS AND METHODS

Forty-five transfused children with cancer were studied for evidence of HCV infection. Patients had not received chemotherapy for a mean of 2.3 years or transfusions for a mean of 3.1 years before being evaluated. Levels of serum aminotransferases [aspartate aminotransferase and alanine aminotransferase (ALT)], hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (HBsAb), and hepatitis B core antibody (HBcAb) were assessed. A second-generation enzyme immunoassay (EIA) was used to screen for anti-HCV antibodies. Positive EIAs were supplemented by a radioimmunoblot assay (RIBA-2).

RESULTS

No patient tested positively for HBsAg, HBsAb, or HBcAb; four of 45 (8.9%) were positive for HCV antibodies by EIA. Three of the four (6.7% of the total) were also positive by RIBA-2 testing. The mean number of donor exposures was not significantly different between HCV-negative versus RIBA-2-positive patients (23.1 vs. 61.7, p = 0.16). ALT levels off therapy and peak ALT levels during therapy were significantly higher in the RIBA-2-positive group versus the HCV-negative group, although 36% of all patients (16 of 45) had at least one elevation in ALT greater than twice the upper limit of normal. All three RIBA-2-positive patients were transfused before institution of universal screening of blood donors for HCV in 1990 and had hepatomegaly noted at least once.

CONCLUSIONS

We have identified a small group of children who may be at high risk for developing chronic active hepatitis and cirrhosis. Testing for HCV should be a routine part of long-term follow-up in children treated for cancer.

Treatment of iron-deficiency anemia complicated by scurvy and folic acid deficiency

We present a case of a child with iron-deficiency anemia, folic acid deficiency, and scurvy. His anemia proved refractory to treatment with iron until he received both folic acid and vitamin C supplementation. This case illustrates the importance of the evaluation of ascorbic acid and folate status in treating iron-deficiency anemia initially refractory to iron supplementation, because multiple nutrient deficiencies may coexist.

Monosomy 7 syndrome in an infant with neurofibromatosis

A 9-month-old boy with known familial neurofibromatosis type I (NF-1) presented with a clinical and laboratory picture suggestive of juvenile chronic myelomonocytic leukemia (JCMMoL). Chromosomal studies obtained from the bone marrow indicated, however, that he had monosomy 7 syndrome. We believe this is the first reported case of monosomy 7 syndrome in a child with NF in the United States, and that this case complements a recent report of two cases of NF, JCMMoL, and monosomy 7 in Japanese children. Since monosomy 7 syndrome is very difficult to differentiate from JCMMoL or acute nonlymphocytic leukemia (ANLL) unless appropriate chromosomal studies are obtained, we believe it is possible that monosomy 7 may occur with increased frequency in patients with NF-1. Monosomy 7 syndrome might therefore be a significant cause of the known association between NF-1 and nonlymphoid leukemia.

Iron deficiency in adolescent girls. Are athletes at increased risk?

Previous studies have indicated a high prevalence of nonanemic iron deficiency in female high school aged endurance athletes. It is not clear, however, whether these adolescents are at more risk for iron depletion than their nonathletic peers. We have previously reported declining serum ferritin levels in response to running but not swimming training in competitive adolescents. In this study we compared these findings with serum ferritin levels and hematologic parameters in a group of nonathletic females from the same community. Mean serum ferritin levels were not significantly different among the groups. A greater percentage of the swimmers and runners had ferritin levels less than 12 ng/ml at the beginning of the season (46.7 and 40%, respectively, compared to 26.7% in the nonathletes), but the differences were not statistically significant. These findings suggest that the high prevalence of hypoferritinemia at the beginning of a competitive season in female high school athletes is similar to that of nonathletes. Other studies have indicated, however, that some sports, particularly running, increase the incidence of iron depletion with training.

Histiocytosis X of the vulva: a case report and review of the literature

Histiocytosis X of the female genital tract is unusual. Thirty-two cases have been reported to date in the world literature. An additional case is reported herein, presenting as a vulvar ulcer in a 2.5-year-old child with osteolytic lesions of the skull, splenomegaly, and otitis media. The diagnosis of histiocytosis X may be established by identifying the Langerhans histiocyte, characterized by nuclear grooves, immunoreactivity for S-100 protein, and pentalamellar cytoplasmic structures seen by electron microscopy. Prognosis is difficult to determine with certainty. However, age of less than 2 years at presentation, multi-organ involvement, and/or organ dysfunction appear to be associated with a less favorable prognosis. The patient presented herein is currently receiving vinblastine chemotherapy for recurrence of disease, manifested as an osteolytic lesion in the skull.

Dystonia musculorum deformans: a 'critical phenomenon' model involving nigral dopaminergic and caudate pathways

In physical systems, a 'critical phenomenon' is a macroscopic occurrence which arises from a change in the relative magnitudes of two or more physical influences whose action is expressed purely in microscopic terms. This concept is potentially valuable in describing the clinical symptomatology of dystonia musculorum deformans (DMD) and other movement disorders. The lateral inhibitory network of Spiny I caudate cells and the profuse neostriatal projection of dopaminergic neurons from the substantia nigra are proposed as anatomic substrates for two short-range neostriatal influences whose interaction contributes to the onset and progression of global dystonic spasm in DMD. Such spasm may be explainable as a critical phenomenon, suggesting new directions for research into the etiology and treatment of this disorder.

Iron deficiency in athletes. Insights from high school swimmers

Previous studies have indicated a high incidence of nonanemic iron deficiency in high school runners, but little is known regarding participants in other sports. The hematologic and iron status of 30 high school swimmers was assessed at the beginning and end of a competitive swim season. Iron depletion (serum ferritin level less than 12 micrograms/L) was initially present in 46.7% of the girls and none of the boys, yet among those subjects with hypoferritinemia there was no evidence of impaired red blood cell production. Serum haptoglobin levels were normal and did not correlate with serum ferritin levels. No significant change was observed in ferritin, hemoglobin, or haptoglobin concentrations during the course of the season. Dietary intake of iron was poor, particularly in the girls, in whom it averaged 43% of the recommended dietary allowance. Menstrual histories suggested an inverse relationship between the amount of menstrual flow and the serum ferritin level. These findings indicate a high prevalence of nonanemic iron deficiency in female high school swimmers that bears no relationship to swim training. Dietary inadequacies and menstrual blood flow appear to be important contributors to the hypoferritinemia observed in these athletes.

Pulse oximetry

The pulse oximeter, a widely used noninvasive monitor of arterial oxygen saturation, has numerous applications in anesthesiology and critical care. Although pulse oximetry is considered sufficiently accurate for many clinical purposes, there are significant limitations on the accuracy and availability of pulse oximetry data. This article reviews both the clinical uses of the pulse oximeter and the limitations on its performance. The pulse oximeter is generally acknowledged to be one of the most important advances in the history of clinical monitoring.

The effect of iron therapy on the exercise capacity of nonanemic iron-deficient adolescent runners

Iron-deficiency anemia impairs exercise capacity, but whether nonanemic iron depletion decreases endurance performance is unclear. In 14 iron-deficient (serum ferritin level, less than 20 micrograms/L [less than 20 ng/L])nonanemic runners, hematologic and treadmill running values were followed up during a competitive season. Following a four-week control period, runners were treated for one month in a double-blind protocol with ferrous sulfate (975 mg/d) or placebo. During treatment, the mean ferritin level rose from 8.7 to 26.6 micrograms/L (8.7 to 26.6 ng/mL) in those patients taking iron and fell from 10.6 to 8.6 micrograms/L (10.7 to 8.6 ng/mL) in the placebo group. Treadmill endurance times improved significantly in the iron-treated runners compared with controls. Endurance time declined in all seven controls (range, 0.07 to 1.30 minutes), while six of seven iron-treated subjects improved their performance (range, 0.03 to 1.92 minutes). No significant differences in maximal or submaximal oxygen consumption, ventilation, or heart rate were observed between the groups except for a 4% increase in maximum oxygen consumption during placebo treatment. These data indicate that nonanemic iron deficiency impairs exercise performance but does not influence gas exchange or cardiac measures.

Iron deficiency in adolescent endurance athletes

Iron deficiency with or without anemia may impair athletic performance. Although previous reports suggest a high incidence of iron deficiency in adolescent athletes, the recommendations for routine screening are unclear. In this study, high school male and female cross-country runners were evaluated by determining serum ferritin, hemoglobin, and red blood cell indexes during an 11-week competitive season. At the beginning of the season one of 30 males and eight of 20 females had iron deficiency, defined as a ferritin level greater than or equal to 12 ng/ml. By the end of the season four additional males and another female became iron deficient, for an overall incidence of 17% in males and 45% in females. Of the 26 runners who were evaluated throughout the season, ferritin levels fell in all nine females and in 14 of 17 males. Iron-deficiency anemia was not observed in any subject. These findings suggest that nonanemic iron deficiency is common in adolescent runners. Although iron deficiency is more common in females, one of every five males was iron depleted by the close of the season. Preseason screening alone is shown to be inadequate for detecting iron-deficient athletes as five runners with low ferritin levels were not identified on the initial evaluation.

Selection of replacement therapy for patients with severe factor VII deficiency

The risk of significant bleeding in patients with severe Factor VII (FVII) deficiency is well documented. However, controversy regarding management exists not only for the choice of FVII replacement product, but also for the desired hemostatic level of FVII. Two case reports are presented where fresh frozen plasma (FFP) and several Factor IX (FIX) complex concentrates were used to achieve hemostasis. Significantly higher FVII levels were achieved with Proplex (FIX Complex, Hyland Therapeutics) than with other products. Although this and other reports indicate that minor bleeding can be controlled with levels of FVII under 15%, life-threatening hemorrhages require higher FVII levels that can be attained only by using a product with a significant FVII content. It is important to know the FVII content of FIX concentrates in order to plan appropriate therapy for patients with FVII deficiency.

Oxygen binding and stability properties of Hb Santa Ana (beta 88 Leu----Pro)

Hb Santa Ana (beta 88 Leu----Pro) was found at a level of 30% of total hemoglobin in red cells from a patient with congenital hemolytic anemia. Since no detailed functional studies of this hemoglobin have been done previously, we determined oxygen equilibrium curves of red cell suspensions, hemolysates, and isolated Hb Santa Ana. The P50 values obtained were 22.5 mm Hg (37 degrees C, pH 7.4) for red cell suspensions (normal mean = 27.0 mm Hg), 10.0 mm Hg (25 degrees C, pH 7.0) for hemolysate (normal = 13.5 mm Hg), and 1.3 mm Hg (25 degrees C, pH 7.0) for isolated Hb Santa Ana. Measurements of mechanical stability of Hb Santa Ana showed that the oxy-form of this hemoglobin was 10 times more unstable than that of Hb S and 100 times more unstable than that of Hb A. The deoxy-form of Hb Santa Ana was as unstable as its oxy-form, indicating that no stabilization (R----T conversion) takes place upon the deoxygenation of Hb Santa Ana.

Inverse correlation between age related abnormalities of T-cell immunity and circulating thymosin alpha 1 levels in haemophilia A

T-cell immunity and serum levels of thymosin alpha 1, beta 2-microglobulin, circulating immune complexes, serum immunoglobulin levels, antibodies to hepatitis surface or core antigen, and to cytomegalovirus, and Epstein-Barr virus were investigated in 51 patients with haemophilia A ranging in age from 2 to 52 years. All patients had received commercial U.S. lyophilized concentrates of antihaemophilic factor (AHF). The mean helper/cytotoxic-suppressor (OKT4/OKT8) ratio of 11 pre-adolescents (1.6 +/- 0.4 SE) was not significantly different from that of age matched normal controls. In contrast, the mean OKT4/OKT8 ratios of 13 adolescent (1.2 +/- 0.2 SE) and 23 adult (0.8 +/- 0.1 SE) haemophiliacs were significantly reduced. Abnormalities of lymphocyte mitogenic responses were found only in adult haemophiliacs. Nine individuals treated with commercial U.S. prothrombin complex concentrates for antibodies directed against AHF or for haemophilia B had normal mean OKT4/OKT8 values. The mean serum thymosin alpha 1 levels for each age category was similar to that of age matched controls; however, regression analysis revealed a significant relationship between elevated thymosin alpha 1 levels and decreased OKT4/OKT8 ratios in adult haemophiliacs (P = 0.012). Although the mean serum level of beta 2-microglobulin was significantly increased in the adult haemophiliac group, there was no correlation between OKT4/OKT8 ratios and any of the other serologic parameters studied.

Life-threatening complications in a child with hemoglobin SD-Los Angeles disease

Hemoglobin SD-Los Angeles is an uncommon sickle hemoglobinopathy. We describe a boy with documented Hb SD-Los Angeles who had experienced acute splenic sequestration, pneumococcal sepsis, aplastic crisis and functional asplenia during his first two years of life. We suggest that children with Hb SD-Los Angeles are at similar risks for the life-threatening complications which characterize sickle cell anemia and should receive the same comprehensive medical care currently recommended for children with Hb SS disease.

Human serum parvovirus as the cause of aplastic crisis in sickle cell disease

An infectious agent has long been suspected as the cause of aplastic crisis in sickle cell disease, but no specific organism has been implicated. We studied six children with sickle cell disease in whom an aplastic crisis developed, looking for evidence of parvoviruslike virus (SPLV) infection using a new radioimmunoassay. All six patients had conclusive evidence of acute infection with SPLV. We postulated that SPLV is the predominant cause of aplastic crises in patients with hemolytic anemia.

Changes in coagulation parameters with exercise in patients with classic hemophilia

Vigorous exercise is known to increase VIII:C and VIIIR:Ag levels transiently in normal individuals. Although exercise programs are frequently advocated in the management of hemophilia, the effects of exercise on coagulation parameters in these patients have not been well studied. Eleven hemophiliacs were exercised on a bicycle ergometer to maximum voluntary effort as evidenced by an increase in pulse, blood pressure, and plasma catecholamine (norepinephrine and epinephrine) levels. The effects of this exercise on coagulation parameters, including functional and antigenic components of the factor VIII molecule, were determined. The entire group demonstrated a decrease in mean prothrombin time (11.7 to 11.2 sec). Four mild hemophiliacs demonstrated an increase in mean VIII:C (14.5% to 17.3%), and VIII:CAg (12% to 17.8%). Changes in VIII:C and VIII:CAg were not noted in the seven severe hemophiliacs. Both severe and mild patients demonstrated significant changes in fibrinogen, factor II, and factor VII after exercise. This study indicates that submaximal exercise modifies coagulation parameters in patients with hemophilia.

Transfusion of frozen erythrocytes from a donor with sickle trait

We describe a nonanaphylactic hemoglobinuric reaction caused by transfusion of frozen red cells, deglycerolyzed by standard technique, obtained from a donor with undiagnosed sickle trait. Although significant hemoglobinemia and hemoglobinuria were noted, the recipient experienced no adverse clinical reactions. The benign clinical course supports the hypothesis that red cell antigen-antibody complexes, rather than free hemoglobin or red cell stroma, are responsible for the life-threatening complications of acute hemolytic transfusion reactions. This report also emphasizes the importance of screening donors of red cells for cryopreservation for sickle trait and the necessity of modifying deglycerolization technique should it be necessary to freeze red cells with AS hemoglobin.