Nilo A. Avila

Pulmonary Nontuberculous Mycobacterial Disease: Prospective Study of a Distinct Preexisting Syndrome

RATIONALE Pulmonary nontuberculous mycobacterial (PNTM) disease is increasing, but predisposing features have been elusive. OBJECTIVES To prospectively determine the morphotype, immunophenotype, and cystic fibrosis transmembrane conductance regulator genotype in a large cohort with PNTM. METHODS We prospectively enrolled 63 patients with PNTM infection, each of whom had computerized tomography, echocardiogram, pulmonary function, and flow cytometry of peripheral blood. In vitro cytokine production in response to mitogen, LPS, and cytokines was performed. Anthropometric measurements were compared with National Health and Nutrition Examination Survey (NHANES) age- and ethnicity-matched female control subjects extracted from the NHANES 2001-2002 dataset. MEASUREMENTS AND MAIN RESULTS Patients were 59.9 (+/-9.8 yr [SD]) old, and 5.4 (+/-7.9 yr) from diagnosis to enrollment. Patients were 95% female, 91% white, and 68% lifetime nonsmokers. A total of 46 were infected with Mycobacterium avium complex, M. xenopi, or M. kansasii; 17 were infected with rapidly growing mycobacteria. Female patients were significantly taller (164.7 vs. 161.0 cm; P < 0.001) and thinner (body mass index, 21.1 vs. 28.2; P < 0.001) than matched NHANES control subjects, and thinner (body mass index, 21.1 vs. 26.8; P = 0.002) than patients with disseminated nontuberculous mycobacterial infection. A total of 51% of patients had scoliosis, 11% pectus excavatum, and 9% mitral valve prolapse, all significantly more than reference populations. Stimulated cytokine production was similar to that of healthy control subjects, including the IFN-gamma/IL-12 pathway. CD4(+), CD8(+), B, and natural killer cell numbers were normal. A total of 36% of patients had mutations in the cystic fibrosis transmembrane conductance regulator gene. CONCLUSIONS Patients with PNTM infection are taller and leaner than control subjects, with high rates of scoliosis, pectus excavatum, mitral valve prolapse, and cystic fibrosis transmembrane conductance regulator mutations, but without recognized immune defects.

Combination therapy in treatment of experimental pulmonary aspergillosis: Synergistic interaction between an antifungal triazole and an echinocandin

Invasive pulmonary aspergillosis is an important cause of morbidity and mortality in immunocompromised patients. Simultaneous inhibition of fungal cell-wall and cell-membrane biosynthesis may result in synergistic interaction against Aspergillus fumigatus. We studied the antifungal activity of micafungin, a new echinocandin, in combination with ravuconazole, a second-generation triazole, against experimental invasive pulmonary aspergillosis in persistently neutropenic rabbits. This combination led to significant reductions in mortality (P</=.001), residual fungal burden (P</=.05), and serum galactomannan antigenemia (P</=.01), compared with either agent alone. Combination therapy also resulted in reduction (P</=.05) of organism-mediated pulmonary injury and of pulmonary infiltrates detected by thoracic computed tomography (P</=.001). No toxicity was observed with the echinocandin-triazole combination. An MTT hyphal damage assay demonstrated significant in vitro synergistic interaction between the antifungal triazole and the echinocandin. The combination of an antifungal triazole and echinocandin may represent a new strategy for treatment of invasive pulmonary aspergillosis.

Progressive Preclinical Interstitial Lung Disease in Rheumatoid Arthritis

BACKGROUND Early detection and treatment for interstitial lung disease (ILD) in patients with rheumatoid arthritis (RA) may ameliorate disease progression. The objective of this study was to identify asymptomatic lung disease and potential therapeutic targets in patients having RA and preclinical ILD (RA-ILD). METHODS Sixty-four adults with RA and 10 adults with RA and pulmonary fibrosis (RAPF) were referred to the National Institutes of Health, Bethesda, Maryland, and underwent high-resolution computed tomography (HRCT) and pulmonary physiology testing. Proteins capable of modulating fibrosis were quantified in alveolar fluid. RESULTS Twenty-one of 64 patients (33%) having RA without dyspnea or cough had preclinical ILD identified by HRCT. Compared with patients without lung disease, patients with RA-ILD had statistically significantly longer histories of cigarette smoking (P< .001), increased frequencies of crackles (P= .02), higher alveolar-arterial oxygen gradients (P= .004), and higher HRCT scores (P< .001). The HRCT abnormalities progressed in 12 of 21 patients (57%) with RA-ILD. The alveolar concentrations of platelet-derived growth factor-AB and platelet-derived growth factor-BB were statistically significantly higher in patients having RA-ILD (mean [SE], 497.3 [78.6] and 1473 [264] pg/mL, respectively) than in patients having RA without ILD (mean [SE], 24.9 [42.4] and 792.7 [195.0] pg/mL, respectively) (P< .001 and P=.047, respectively). The concentrations of interferon gamma and transforming growth factor beta(2) were statistically significantly lower in patients having RAPF (mean [SE], 5.59 [1.11] pg/mL and 0.94 [0.46] ng/mL, respectively) than in patients having RA without ILD (mean [SE], 14.1 [1.9] pg/mL and 2.30 [0.39] ng/mL, respectively) (P=.001 and P=.006, respectively) or with preclinical ILD (mean [SD], 11.4 [2.6] pg/mL and 3.63 [0.66] ng/mL, respectively) (P=.04 and P=.007, respectively). Compared with patients having stable RA-ILD, patients having progressive RA-ILD had statistically significantly higher frequencies of treatment using methotrexate and higher alveolar concentrations of interferon gamma and transforming growth factor beta(1) (P=.046, P=.04, and P=.04, respectively). CONCLUSIONS Asymptomatic preclinical ILD, which is detectable by HRCT, may be prevalent and progressive among patients having RA. Cigarette smoking seems to be associated with preclinical ILD in patients having RA, and treatment using methotrexate may be a risk factor for progression of preclinical ILD. Quantification of alveolar proteins indicates that potential pathogenic mechanisms seem to differ in patients having RA-ILD and symptomatic RAPF.

Antifungal Efficacy of Caspofungin (MK-0991) in Experimental Pulmonary Aspergillosis in Persistently Neutropenic Rabbits: Pharmacokinetics, Drug Disposition, and Relationship to Galactomannan Antigenemia

ABSTRACT The antifungal efficacy, pharmacokinetics, and safety of caspofungin (CAS) were investigated in the treatment and prophylaxis of invasive pulmonary aspergillosis due to Aspergillus fumigatus in persistently neutropenic rabbits. Antifungal therapy consisted of 1, 3, or 6 mg of CAS/kg of body weight/day (CAS1, CAS3, and CAS6, respectively) or 1 mg of deoxycholate amphotericin B (AMB)/kg/day intravenously for 12 days starting 24 h after endotracheal inoculation. Prophylaxis (CAS1) was initiated 4 days before endotracheal inoculation. Rabbits treated with CAS had significant improvement in survival and reduction in organism-mediated pulmonary injury (OMPI) measured by pulmonary infarct score and total lung weight (P < 0.01). However, animals treated with CAS demonstrated a paradoxical trend toward increased residual fungal burden (log CFU per gram) and increased serum galactomannan antigen index (GMI) despite improved survival. Rabbits receiving prophylactic CAS1 also showed significant improvement in survival and reduction in OMPI (P < 0.01), but there was no effect on residual fungal burden. In vitro tetrazolium salt hyphal damage assays and histologic studies demonstrated that CAS had concentration- and dose-dependent effects on hyphal structural integrity. In parallel with a decline in GMI, AMB significantly reduced the pulmonary tissue burden of A. fumigatus (P ≤ 0.01). The CAS1, CAS3, and CAS6 dose regimens demonstrated dose-proportional exposure and maintained drug levels in plasma above the MIC for the entire 24-h dosing interval at doses that were ≥3 mg/kg/day. As serial galactomannan antigen levels may be used for therapeutic monitoring, one should be aware that profoundly neutropenic patients receiving echinocandins for aspergillosis might have persistent galactomannan antigenemia despite clinical improvement. CAS improved survival, reduced pulmonary injury, and caused dose-dependent hyphal damage but with no reduction in residual fungal burden or galactomannan antigenemia in persistently neutropenic rabbits with invasive pulmonary aspergillosis.

Antifungal Activity and Pharmacokinetics of Posaconazole (SCH 56592) in Treatment and Prevention of Experimental Invasive Pulmonary Aspergillosis: Correlation with Galactomannan Antigenemia

ABSTRACT The antifungal efficacy, safety, and pharmacokinetics of posaconazole (SCH 56592) (POC) were investigated in treatment and prophylaxis of primary pulmonary aspergillosis due to Aspergillus fumigatus in persistently neutropenic rabbits. Antifungal therapy consisted of POC at 2, 6, and 20 mg/kg of body weight per os; itraconazole (ITC) at 2, 6, and 20 mg/kg per os; or amphotericin B (AMB) at 1 mg/kg intravenously. Rabbits treated with POC showed a significant improvement in survival and significant reductions in pulmonary infarct scores, total lung weights, numbers of pulmonary CFU per gram, numbers of computerized-tomography-monitored pulmonary lesions, and levels of galactomannan antigenemia. AMB and POC had comparable therapeutic efficacies by all parameters. By comparison, animals treated with ITC had no significant changes in outcome variables in comparison to those of untreated controls (UC). Rabbits receiving prophylactic POC at all dosages showed a significant reduction in infarct scores, total lung weights, and organism clearance from lung tissue in comparison to results for UC (P < 0.01). There was dosage-dependent microbiological clearance of A. fumigatus from lung tissue in response to POC. Serum creatinine levels were greater (P < 0.01) in AMB-treated animals than in UC and POC- or ITC-treated rabbits. There was no elevation of serum hepatic transaminase levels in POC- or ITC-treated rabbits. The pharmacokinetics of POC and ITC in plasma demonstrated dose dependency after multiple dosing. The 2-, 6-, and 20-mg/kg dosages of POC maintained plasma drug levels above the MICs for the entire 24-h dosing interval. In summary, POC at ≥6 mg/kg/day per os generated sustained concentrations in plasma of ≥1 μg/ml that were as effective in the treatment and prevention of invasive pulmonary aspergillosis as AMB at 1 mg/kg/day and more effective than cyclodextrin ITC at ≥6 mg/kg/day per os in persistently neutropenic rabbits.

Effect of pirfenidone on the pulmonary fibrosis of Hermansky-Pudlak syndrome.

Hermansky-Pudlak syndrome (HPS) consists of oculocutaneous albinism, a platelet storage pool deficiency and, in patients with HPS1 gene mutations, a progressive, fatal pulmonary fibrosis. We investigated the safety and efficacy of an antifibrotic agent, pirfenidone (800 mg, t.i.d.), in treating 21 adult Puerto Rican HPS patients, including 20 homozygous for the same HPS1 mutation. Patients were examined every 4 months for up to 44 months in a randomized, placebo-controlled trial, with rate of change in pulmonary function values as outcome parameters. Using the complete data set of 130 patient admissions, a repeated measures model showed that 11 pirfenidone-treated patients lost FVC at a rate 5% of predicted ( approximately 400 mL) per year slower than 10 placebo-treated patients (p=0.001). A random coefficients model showed no significant difference. However, using data restricted to patients with an initial FVC >50% of predicted, both models showed the pirfenidone group losing FVC (p<0.022), FEV(1) (p<0.0007), TLC (p<0.001), and DL(CO) (p<0.122) at a rate approximately 8%/year slower than the placebo group. Clinical and laboratory side effects were similar in the two groups. Pirfenidone appears to slow the progression of pulmonary fibrosis in HPS patients who have significant residual lung function.

Future directions in the study and management of congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Dr. Deborah P. Merke (Warren Grant Magnuson Clinical Center, National Institutes of Health [NIH], Bethesda, Maryland): Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is one of the most common known autosomal recessive disorders (1). In this condition, impaired cortisol production leads to a lack of negative glucocorticoid feedback on the pituitary, hypothalamus, and suprahypothalamic centers, resulting in an increase in corticotropin, a buildup of cortisol precursors, and androgen excess (Figure 1). The carrier frequency of the classic or severe form of 21-hydroxylase deficiency is approximately 1 in 60 persons (2). The carrier frequency of the nonclassic or mild form ranges from 1 in 5 to 1 in 50 persons, depending on ethnicity (3); it is most common in Hispanic and Ashkenazi Jewish populations. Because congenital adrenal hyperplasia has a high frequency, a variable presentation in children and adults, and potential complications, a thorough understanding of the disorder is of great importance to clinicians working in internal medicine, reproductive medicine, and pediatrics. Figure 1. Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. left middle ACTH right The classic form of congenital adrenal hyperplasia presents in infancy and early childhood as signs and symptoms of virilization with or without adrenal insufficiency. It is subcategorized as salt-losing or non-salt-losing, reflecting the degree of mineralocorticoid deficiency (4). In the early 1950s, cortisone therapy was found to be effective in treating adrenal insufficiency and excess androgen production in patients with congenital adrenal hyperplasia (5). Since the discovery of cortisone therapy and the addition of mineralocorticoid supplementation, the morbidity and mortality of patients with classic disease have markedly decreased, and these patients now have a long life span. Thus, long-term consequences of current treatments are an important consideration. The 21-hydroxylase-deficient mouse, which was described in a Japanese study by Shiroishi and coworkers (6), has been a useful model for gaining new insights into the pathophysiology of the disease in humans and for developing new therapeutic strategies. The mouse model revealed an abnormal hypothalamic-pituitary-adrenal feedback mechanism (7), alterations in the structure and function of the adrenal medulla (8), and a good response to gene therapy (9). Further exploration of the disease process in this animal model is an essential aspect of the bench-to-bedside research approach to improving the human condition. Abnormalities in both the structure and function of the adrenal medulla have been shown in patients with classic congenital adrenal hyperplasia (10). This finding may explain why some children with the severe form of 21-hydroxylase deficiency are prone to adrenal crises, hypoglycemia, and cardiovascular collapse in response to febrile illnesses or other stressful circumstances, despite adequate glucocorticoid replacement. There are many unresolved clinical problems in the management of classic 21-hydroxylase deficiency in both males and females. Among the most critical are inadequate response to glucocorticoid and mineralocorticoid replacement therapy, iatrogenic Cushing syndrome (11), adult short stature (12, 13), and oligo-amenorrhea and infertility in women (14, 15). The new treatment approaches to classic congenital adrenal hyperplasia represent potential solutions to these unresolved issues. In a long-term randomized clinical trial, the NIH is testing a new treatment regimen consisting of reduced hydrocortisone dose, an antiandrogen, and an aromatase inhibitor (16, 17). Bilateral adrenalectomy is being performed in selected cases (18). Future therapies include a new class of drug called corticotropin-releasing hormone antagonists (19) and possibly gene therapy (9). Nonclassic congenital adrenal hyperplasia, the mild form of the disease, is a common cause of hyperandrogenism in women. Although the same gene is involved in both the severe and mild forms, genetic mutations typically associated with the mild form of the disease only partially impair 21-hydroxylase activity. Thus, the patient with nonclassic congenital adrenal hyperplasia is in a fully compensated state; she does not have cortisol deficiency but rather manifestations of hyperandrogenism, usually later in childhood, around puberty, or in early adulthood (20, 21). Nonclassic congenital adrenal hyperplasia is an important consideration in the differential diagnosis of female patients with symptoms or signs of hyperandrogenism, such as severe cystic acne, hirsutism, male pattern baldness, oligo-amenorrhea, or infertility. Nonclassic 21-hydroxylase deficiency, especially when it exists in conjunction with hyperinsulinemia, often results in the polycystic ovary syndrome, with its characteristic reproductive and metabolic comorbid conditions. Recognition of this disorder is crucial for family planning and management in women with hyperandrogenism. Men with nonclassic congenital adrenal hyperplasia are usually asymptomatic but may also present with early puberty or testicular adrenal rests. Another recognized comorbid condition associated with congenital adrenal hyperplasia is activation of ectopic adrenal tissue resulting in adrenal rest tumors (22). These tumors are most commonly found in the testes of men with classic or nonclassic congenital adrenal hyperplasia and often result in oligo-azoospermia and infertility (23). New advances in the diagnostic evaluation and management of these tumors are presented in this paper. Genetics The gene for 21-hydroxylase lies on chromosome 6 within the HLA locus of the major histocompatibility system; thus, 21-hydroxylase deficiency is an HLA-linked disorder (24). Two homologous genes result from ancestral duplication. CYP21B is the active gene; CYP21A is an inactive pseudogene. The location of the CYP21B gene makes it vulnerable to relatively large genomic DNA exchanges with its homologous gene, CYP21A. The proximity of these genes and their location within the HLA region, which has a high rate of recombination, facilitate such exchanges. Therefore, the 21-hydroxylase locus shows an unusual degree of variability between individuals (25, 26). 21-Hydroxylase deficiency is unique because most mutations result from the transfer of sequences between pseudogenes and active genes (27). When deleterious sequences that normally present in the pseudogene are transferred to the active gene, they render the gene incapable of encoding a normal enzyme. The term gene conversion is used to denote the transfer of sequences between homologous genes; however, the mechanism is poorly understood. Specific mutations typically correspond to the three types of 21-hydroxylase deficiency: salt-losing, non-salt-losing (simple virilizing), and nonclassic congenital adrenal hyperplasia (Figure 2). In vitro studies have shown that mutations resulting in complete inactivation of 21-hydroxylase activity are associated with the salt-losing phenotype, those that reduce 21-hydroxylase activity to approximately 2% are associated with the non-salt-losing phenotype, and those that reduce 21-hydroxylase activity to 10% to 75% are associated with the nonclassic phenotype (28, 29) (Figure 2). Most patients are compound heterozygotes, and the severity of the disease is determined by the activity of the less severely affected allele. Figure 2. The 10 most common genetic mutations found in 21-hydroxylase deficiency. SL NSL NC CYP21B The degree of functional impairment predicted by individual mutations usually corresponds to the clinical severity observed in a given patient. However, genotype does not always accurately predict phenotype. This disparity between genotype and phenotype may be due to androgen sensitivity or to other genes that cause differences in steroid metabolism and homeostasis. Animal Model for 21-Hydroxylase Deficiency Dr. Stefan R. Bornstein (Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development [NICHD], NIH): In the mouse, the 21-hydroxylase gene also lies within the major histocompatibility locus (30). Mice with spontaneous 21-hydroxylase deficiency have a deletion of the 21-hydroxylase gene (6, 7, 31). 21-Hydroxylase activity is completely absent in newborn mice homozygous for this deletion, and this absence is lethal in the early postnatal stage. The deficiency of glucocorticoids results in adrenocortical hyperplasia and plasma accumulation of precursor steroids in both mice and humans with congenital adrenal hyperplasia. In mice, which normally lack adrenal 17--hydroxylase, the enzymatic blockade results mainly in accumulation of progesterone. Most of the affected mice, if not treated with glucocorticoids and mineralocorticoids, die within 1 week (6, 7, 31). Although the disease state of the 21-hydroxylase-deficient mouse is not completely comparable to human congenital adrenal hyperplasia, it has provided a useful model with which to examine molecular and cellular mechanisms of the disease and test new therapeutic interventions. The adrenal glands of affected mice demonstrate a significant increase in expression of messenger RNA of steroidogenic acute regulatory protein (Figure 3), which is the rate-limiting step for steroidogenesis (32). Corticotropin regulates the expression of this protein, and the increase of messenger RNA reflects impaired negative feedback with increased corticotropin production. Moreover, one study showed that prenatal dexamethasone treatment (0.5 to 2 g/d) failed to adequately suppress fetal adrenal hormones in mice, suggesting hyperactivity of the hypothalamic-pituitary corticotroph axis and insensitivity to glucocorticoid feedback inhibition (7). Intrauterine glucocorticoid deficiency may affect the sensitivity of feedback inhibition postnatally, thus blunting the central effects of treatment

Serum Vascular Endothelial Growth Factor-D Levels in Patients With Lymphangioleiomyomatosis Reflect Lymphatic Involvement

BACKGROUND Lymphangioleiomyomatosis (LAM) is a rare multisystem disorder affecting primarily women of child-bearing age, and characterized by cystic lung destruction, tumors of the kidney (angiomyolipomas [AMLs]), and involvement of the axial lymphatics (lymphangioleiomyomas). Patients with LAM experience loss of pulmonary function attributed to the proliferation of abnormal-appearing smooth muscle-like cells (LAM cells). It is possible to group the LAM population by the presence or absence of extrapulmonary involvement (eg, AMLs, lymphangioleiomyomas, chylous effusions). Serum vascular endothelial growth factor (VEGF)-D, a lymphangiogenic factor, is higher in LAM patients than in healthy volunteers and has been proposed as a tool in the differential diagnosis of cystic lung disease. We assessed serum VEGF-D concentrations in relationship to clinical phenotype in LAM patients. METHODS Serum VEGF-D levels were quantified by enzyme immunosorbent assay for 111 patients with LAM and 40 healthy volunteers. VEGF-D levels in patients with pulmonary LAM, with or without extrapulmonary manifestations, were compared to those of healthy volunteers. RESULTS Serum VEGF-D levels were greater in patients with LAM compared to those of healthy volunteers (p < 0.001). However, when patient samples were grouped based on the extent of lymphatic extrapulmonary involvement (eg, lymphangioleiomyomas and adenopathy), the statistical difference was maintained only for patients with LAM with lymphatic involvement (p < 0.001), not for those patients whose disease was restricted to the lung. Serum VEGF-D levels are a good biomarker for lymphatic involvement (area under the curve [AUC], 0.845; p < 0.0001), and a fair predictor for LAM disease (AUC, 0.751; p < 0.0001). Serum levels correlated to CT scan grade (p = 0.033). CONCLUSIONS Serum VEGF-D concentration is a measure of lymphatic involvement in patients with LAM.

Combination Therapy in Treatment of Experimental Pulmonary Aspergillosis: In Vitro and In Vivo Correlations of the Concentration- and Dose- Dependent Interactions between Anidulafungin and Voriconazole by Bliss Independence Drug Interaction Analysis

ABSTRACT We studied the antifungal activity of anidulafungin (AFG) in combination with voriconazole (VRC) against experimental invasive pulmonary aspergillosis (IPA) in persistently neutropenic rabbits and further explored the in vitro and in vivo correlations by using Bliss independence drug interaction analysis. Treatment groups consisted of those receiving AFG at 5 (AFG5 group) and 10 (AFG10 group) mg/kg of body weight/day, VRC at 10 mg/kg every 8 h (VRC group), AFG5 plus VRC (AFG5+VRC group), and AFG10 plus VRC (AFG10+VRC group) and untreated controls. Survival throughout the study was 60% for the AFG5+VRC group, 50% for the VRC group, 27% for the AFG10+VRC group, 22% for the AFG5 group, 18% for the AFG10 group, and 0% for control rabbits (P < 0.001). There was a significant reduction of organism-mediated pulmonary injury, measured by infarct scores, lung weights, residual fungal burdens, and galactomannan indexes, in AFG5+VRC-treated rabbits versus those treated with AFG5 and VRC alone (P < 0.05). In comparison, AFG10+VRC significantly lowered only infarct scores and lung weights in comparison to those of AFG10-treated animals (P < 0.05). AFG10+VRC showed no significant difference in other outcome variables. Significant Bliss synergy was found in vivo between AFG5 and VRC, with observed effects being 24 to 30% higher than expected levels if the drugs were acting independently. These synergistic interactions were also found between AFG and VRC in vitro. However, for AFG10+VRC, only independence and antagonism were observed among the outcome variables. We concluded that the combination of AFG with VRC in treatment of experimental IPA in persistently neutropenic rabbits was independent to synergistic at a dosage of 5 mg/kg/day but independent to antagonistic at 10 mg/kg/day, as assessed by Bliss independence analysis, suggesting that higher dosages of an echinocandin may be deleterious to the combination.

Treatment of metastatic osteosarcoma with the somatostatin analog OncoLar: Significant reduction of insulin-like growth factor-1 serum levels

Background Insulin-like growth factor-1 (IGF-1) has been implicated in the growth and/or metastasis of osteosarcoma (OS) and chondrosarcoma based on in vitro and experimental animal studies. Study Purpose To determine the degree of growth hormone (GH), IGF-1 axis blockade, toxicities, and antitumor effect of OncoLar (ONC) (Novartis, East Hanover, NJ, U.S.A.) in OS. Design/Methods A phase 1 study with ONC enrolled 21 OS patients (median age 19 y) in four cohorts: ONC 60 mg or 90 mg intramuscularly every 4 weeks with/without tamoxifen (TAM) 20 mg oral daily. Results There were no dose-limiting toxicities. Nineteen percent of patients had grade III drug-related toxicities including: 62% of patients showed progressive disease after two courses (8 wk). Nineteen percent received four courses. No clinical responses were observed. At weeks two and eight of therapy, IGF-1 serum levels dropped 46% (P < 0.0001, n = 21) and 53% (P = 0.003, n = 10). The difference of the area under the curve (AUC) minus baseline AUC (&Dgr;AUC) for arginine-stimulated GH serum levels at week two was lower than baseline (P < 0.01). At weeks two and eight, GH peak values were lower than baseline (P < 0.0001 and P = 0.002, respectively). Conclusions A long-acting somatostatin analog was able to lower IGF-1 levels of OS patients. IGF-BP-3 and GH were only transiently reduced. Although ONC was well tolerated, no sustained clinical responses were observed. The pathophysiology of serum versus tissue concentrations of IGF-1 as well as the interplay of IGFs, IGF-binding proteins, and other growth factors and cytokines in osteosarcoma warrants further investigation. A better understanding of these processes should lead to a more effective exploitation of these pathways for the targeted therapy of OS.