Treatment of pituitary-dependent Cushing's disease with the multireceptor ligand somatostatin analog pasireotide (SOM230): a multicenter, phase II trial

CONTEXT

There is currently no medical therapy for Cushing's disease that targets the pituitary adenoma. Availability of such a medical therapy would be a valuable therapeutic option for the management of this disorder.

OBJECTIVE

Our objective was to evaluate the short-term efficacy of the novel multireceptor ligand somatostatin analog pasireotide in patients with de novo, persistent, or recurrent Cushing's disease.

DESIGN

We conducted a phase II, proof-of-concept, open-label, single-arm, 15-d multicenter study.

PATIENTS

Thirty-nine patients with either de novo Cushing's disease who were candidates for pituitary surgery or with persistent or recurrent Cushing's disease after surgery without having received prior pituitary irradiation.

INTERVENTION

Patients self-administered sc pasireotide 600 microg twice daily for 15 d.

MAIN OUTCOME MEASURE

Normalization of urinary free cortisol (UFC) levels after 15 d treatment was the main outcome measure.

RESULTS

Of the 29 patients in the primary efficacy analysis, 22 (76%) showed a reduction in UFC levels, of whom five (17%) had normal UFC levels (responders), after 15 d of treatment with pasireotide. Serum cortisol levels and plasma ACTH levels were also reduced. Steady-state plasma concentrations of pasireotide were achieved within 5 d of treatment. Responders appeared to have higher pasireotide exposure than nonresponders.

CONCLUSIONS

Pasireotide produced a decrease in UFC levels in 76% of patients with Cushing's disease during the treatment period of 15 d, with direct effects on ACTH release. These results suggest that pasireotide holds promise as an effective medical treatment for this disorder.

The role of ITAM- and ITIM-coupled receptors in platelet activation by collagen

The major activation-inducing collagen receptor glycoprotein VI (GPVI) has been cloned within the last two years. It is a member of the Ig superfamily of proteins and is constitutively associated with the ITAM-bearing Fc receptor gamma-chain (FcR gamma-chain). GPVI signals through a pathway that involves several of the proteins used by Fc, B- and T-lymphocyte receptors and which takes place in glycolipid-enriched membrane domains in the plasma membrane known as GEMs. Responses to GPVI are regulated by PECAM-1 (CD31) and possibly other ITIM-bearing receptors. Despite a pivotal role for GPVI, there are important differences between signalling events to collagen and GPVI-specific ligands. This may reflect a role for co-receptors in the response to collagen.

The effects of tubulin-binding agents on stretch-induced ventricular arrhythmias

Stretch-activated ion channels have been identified as transducers of mechanoelectric coupling in the heart, where they may play a role in arrhythmogenesis. The role of the cytoskeleton in ion channel control has been a topic of recent study and the transmission of mechanical stresses to stretch-activated channels by cytoskeletal attachment has been hypothesized. We studied the arrhythmogenic effects of stretch in 16 Langendorff-perfused rabbit hearts in which we pharmacologically manipulated the microtubular network of the cardiac myocytes. Group 1 (n=5) was treated with colchicine, which depolymerizes microtubules, and Group 2 (n=6) was treated with taxol, which polymerizes microtubules. Stretch-induced arrhythmias were produced by transiently increasing the volume of a fluid-filled left ventricular balloon with a volume pump driven by a computer-controlled stepper motor. Electrical events were recorded by a contact electrode which provided high-fidelity recordings of monophasic action potentials and stretch-induced depolarizations. The probability of eliciting a stretch-induced arrhythmia increased (0.22+/-0.11 to 0.62+/-0.19, p=0.001) in hearts treated with taxol (5 microM), whereas hearts treated with colchicine (100 microM) showed no statistically significant change. We conclude that proliferation of microtubules increased the arrhythmogenic effect of transient left ventricle diastolic stretch. This result indicates a possible mode of arrhythmogenesis in chemotherapeutic patients and patients exhibiting uncompensated ventricular hypertrophy. The data would indicate that the cytoskeleton represents a possible target for antiarrhythmic therapies.

Correlation between human immunodeficiency virus genotypic resistance and virologic response in patients receiving nelfinavir monotherapy or nelfinavir with lamivudine and zidovudine

The relationship between detectable human immunodeficiency virus (HIV) genotypic resistance and virologic response was compared in patients receiving nelfinavir as monotherapy (16 weeks) or in combination with lamuvidine and zidovudine (48 weeks). Two patient groups were defined on the basis of the presence or absence of substitutions associated with nelfinavir, a protease (PR) inhibitor, and/or a reverse transcriptase (RT) inhibitor. HIV RNA levels <50 copies/mL were achieved in 17 (85%) of 20 combination-therapy patients without genotypic resistance (PR-RT(-)) versus only 1 (17%) of 6 patients with genotypic resistance (PR-RT(+)). PR-RT(-) patients exhibited greater and more durable virus suppression compared with PR-RT(+) patients. All 6 PR-RT(+) patients had virus with M184V (lamuvidine resistance); 3 isolates also contained D30N (nelfinavir resistance). M184V preceded D30N in all determinable instances. In this study, suppression of HIV replication to <50 copies/mL was associated with durable response and reduced incidence of resistance. Results also indicate that combination regimens can fail despite the absence of detectable genotypic PR resistance.

Minimal evidence of platelet and endothelial cell reactive antibodies in thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a syndrome characterized by microvascular thrombosis with thrombocytopenia and end-organ injury. Evidence suggests that platelet or endothelial cell injury may be initial pathological events in TTP. A number of factors in patient plasma, including immunoglobulins, have been proposed to mediate cellular injury in TTP. However, systematic analyses of TTP patient plasma for the presence of platelet or endothelial cell antibodies are lacking. We, therefore, analyzed 48 TTP patient plasma samples for the presence of platelet and endothelial cell antibodies by using enzyme-linked immunosorbent assay, flow cytometry, and microlymphocytotoxicity. Twelve of 48 TTP patient samples (25%) reacted against purified platelet glycoproteins. Nine (19%) also contained antibodies that bound to allogeneic target platelets in flow-cytometric assays. Nine of 48 samples (19%) contained antibodies to human umbilical vein endothelial cells in flow-cytometric assays, and seven of 48 patient samples (15%) bound to human dermal microvascular endothelial cells. Six of 48 (13%) patient plasma samples contained antibodies that bound to human umbilical vein endothelial cells activated with gamma-interferon and tumor necrosis factor-alpha. Of twenty samples that were reactive in one or more platelet or endothelial cell assay, eight contained human leukocyte antigen antibodies reactive in microlymphocytotoxicity. These studies demonstrate that antibodies reactive against platelet or endothelial cell antigens are not prevalent in TTP, and that more than a third of antibodies detected are human leukocyte antigen alloantibodies. Our findings suggest that autoantibodies against platelets or endothelial cells are not important in the pathogenesis of this syndrome.

Infected macaques that controlled replication of SIVmac or nonpathogenic SHIV developed sterilizing resistance against pathogenic SHIV(KU-1)

Twenty macaques were used to evaluate the ability of nonpathogenic SIV(mac) or nonpathogenic chimeric SIV-HIV (SHIV) to induce protection in macaques against superinfection with a pathogenic variant of SHIV (SHIV(KU-1)) originally containing the tat, rev, vpu, and env of HIV-1 (strain HXB2) in a genetic background of SIV(mac)239. Specifically, three macaques inoculated with molecularly cloned, macrophage-tropic SIV(mac)LG1 developed an early systemic infection but recovered with only traces of SIV(mac) DNA in visceral lymphoid tissues. These animals were then inoculated parenterally with pathogenic SHIV(KU-1). All three animals resisted infection with SHIV(KU-1), as indicated by lack of virus recovery and absence of SHIV-specific env and vpu sequences in the visceral lymphoid tissues and multiple regions in the CNS. We also examined the ability of five macaques that had been inoculated with nonpathogenic SHIV (NP-SHIV) to withstand challenge with the pathogenic SHIV(KU-1). Like the SIV(mac)LG1-inoculated macaques, these animals also resisted SHIV(KU-1) challenge as judged by the inability to recover infectious virus, normal CD4+ T cell counts, and the absence of SHIV(KU-1) signature sequences in the lymph node tissue. Thus, eight of eight animals that developed control over primary lentivirus infections had also developed resistance to infection with pathogenic SHIV(KU-1). Three groups of macaques were used as controls for this study. The first group consisted of six macaques inoculated with SHIV(KU-1) alone. All animals developed viremia, showed severe loss of CD4+ T cells within 4 weeks, and succumbed to AIDS within 6 months. The second group of three macaques was inoculated first with SHIV(KU-1) and inoculated later with uncloned, neurovirulent SIV(mac)7F-Lu. A third group of three macaques was inoculated with SIV(mac)7F-Lu followed by inoculation with SHIV(KU-1). PCR analyses using oligonucleotide primers specific for the SIV or HIV env revealed that macaques from the last two groups had widespread infection with both SHIV(KU-1) and SIV(mac), indicating that animals that failed to control productive replication of either SHIV(KU-1) or SIV(mac)7F-Lu could not resist superinfection with the other virus. These data indicate that sterilizing immunity against the virulent SHIV could be induced in animals that had experienced an immunizing infection. Moreover, the divergence of the envelope glycoprotein of the protective avirulent and virulent challenge virus suggests that a single vaccine could protect against infection with a virus containing a different envelope glycoprotein.

A cell-free stock of simian-human immunodeficiency virus that causes AIDS in pig-tailed macaques has a limited number of amino acid substitutions in both SIVmac and HIV-1 regions of the genome and has offered cytotropism

We have examined both the sequence changes in the LTR, gag, vif, vpr, vpx, tat, rev, vpu, env, and nef genes and the cell tropism of a cell-free stock of chimeric simian-human immunodeficiency virus (SHIV) isolated from the cerebrospinal fluid of a pig-tailed macaque (PNb) that developed AIDS. This virus (SHIVKU-1) is highly pathogenic when inoculated into other macaques. DNA sequence analysis of PCR-amplified products revealed a total of 5 nucleotide changes in the LTR while vif had 2 consensus amino acid changes. The gag, vif, and vpx had no consensus amino acid substitutions, whereas vpr had 1 consensus substitution. The tat and rev genes of the HXB2 region of SHIVKU-1 had 2 and 1 consensus amino acid changes, respectively. The vpu gene of the HXB2 region of SHIV, which originally had an ACG at the beginning of the gene, reverted to an initiation ATG codon and in addition contained a consensus amino acid substitution at position 69 of this protein. As expected, the majority of the nucleotide substitutions were found in the env and nef genes. Thirteen and 5 amino acid changes were predicted for the corresponding Env and Nef proteins, respectively. In addition, one-third of the env gene clones isolated from the SHIVKU-1 stock had a 5-amino-acid deletion in the V4 region. Using three independent assays, we determined that the changes in the SHIVKU-1 were associated with an increase in the efficiency of replication in macrophages. The strikingly few consensus changes in the virus suggest that conversion of this virus to one capable of causing AIDS in pig-tailed macaques was associated with relatively few changes in the viral envelope and/or accessory genes. These results will provide the basis for the development of a pathogenic, molecular clone of SHIV capable of causing AIDS in pig-tailed macaques.

Modulation of cranial bone healing with a heparin-like dextran derivative

Substituted dextran polymers have been shown to bind growth factors and protect them from enzymatic degradation. Using this information, other researchers have been able to use these substituted dextrans to enhance the healing of bone in an environment where bone would otherwise not regenerate. We used substituted dextran polymers to evaluate their ability to accelerate the healing of cranial bone in a rabbit model. We were able to document a more rapid rate of healing and demonstrate micrographic evidence to support that conclusion. Possible mechanisms are postulated.

Computer-assisted image analysis of tumor sections for a new thrombospondin receptor

BACKGROUND

A cell surface receptor (50 kd) has been recently identified in malignant cells that recognizes the tumor cell adhesive domain (ie, cysteine-serine-valine-threonine-cysteine-glycine [CSVTCG]) of thrombospondin (TSP). This CSVTCG-specific TSP receptor can be considered as a new tumor marker, and its concentration on the cell surface may correlate directly with the capacity of tumor cells to invade and metastasize.

MATERIALS AND METHODS

Six patients with primary, stages III and IV squamous cell carcinomas of the head and neck were studied. Tumor sections were specifically stained for this receptor with immunohistochemical techniques. The stained specimens were then subjected to computer-assisted image analysis. The area of positive staining and the heterogeneity of the pattern of staining were compared to peritumoral angiogenesis and clinical outcome of the patients.

RESULTS

The results indicate that those patients with a high and homogenous positive stain score (mean +/- standard error [SE] 78 +/- 5%) for the CSVTCG-specific TSP receptor had high microvessel density and died from metastatic disease within 12 months of initial treatment (correlation coefficients = 0.95 and 1, respectively). Patients with a low and heterogenous positive stain score for receptor (mean +/- SE 8 +/- 2%; P < 0.001) had low microvessel counts and remained disease-free for at least 2 years. There was no relationship between receptor density and histologic classification of the primary tumors.

CONCLUSION

The CSVTCG-specific TSP receptor, quantified through image analysis of immunohistochemical stained tissue sections, is highly predictive of clinical outcome in patients with squamous cell carcinomas of the head and neck.

The relationship of angiogenesis to biological activity in human squamous cell carcinomas of the head and neck

Tumor angiogenesis has recently been related to tumor growth and metastasis, which determine the clinical outcome of the patient. This study was designed to determine the relationship between angiogenesis in primary squamous cell carcinomas (SCC) of the head and neck and the development of recurrent or metastatic disease, or both. Different SCC of the head and neck were studied. Microvessels were selectively stained using a monoclonal antibody for factor VIII. Microvessel counts were performed in the tumor, in the tissues immediately adjacent, and in normal tissues of similar topographies. Microvessel counts were then correlated with clinical outcome (development of recurrent or metastatic disease, or both). Recurrent or metastatic disease, or both, developed in patients with high microvessel counts (mean, 121.25) in the tissues adjacent to the tumor 7 to 16 months after initial treatment. Those with low microvessel counts (mean, 33.75) were disease-free for 16 months to 6 years (p < 0.01). Microvessel counts inside the tumor were also higher in those in whom recurrences or metastasis, or both, developed, but were not statistically significant. In this study, angiogenesis was directly related to clinical outcome. Thus, angiogenesis may be an independent predictor of recurrent or metastatic disease, or both, which could help in the selection of patients with SCC of the head and neck for aggressive therapy.

A response to the British Paediatric Association report on paediatric intensive care services

The publication of the long-awaited report by the British Paediatric Association (BPA) (1993) in conjunction with the Department of Health (DoH) has added yet another dimension to the already complex problem of providing comprehensive intensive care services.

Persistence of sham feeding after intragastric meals in rats

In rats on a stringent deprivation schedule and at reduced body weight, an intragastric load of liquid diet that equals or exceeds normal meal size has no effect at all on subsequent sham feeding of milk diet or of glucose. Removing the acute deprivation period and reversing, or preventing, severe weight reduction has no effect on this "persistence" of sham feeding: a full intragastric meal may leave sham feeding quite unaffected, even if that meal follows the previous meal at a physiological interval, in rats at normal weight. These data contrast with graded, dose-dependent effects of other manipulations by other investigators. Perhaps such effects depend on conditioned or anticipatory controls of feeding, whereas our findings apply to unconditioned controls.

Differences in antigen expression between neoplastic and nonneoplastic gallbladder epithelium. An immunohistochemical study

Immunoreactivity for a panel of 15 monoclonal antibodies (MAbs), which are known to react with different gastrointestinal tumor antigens, was assessed in formalin-fixed paraffin-embedded sections that were prepared from cholecystectomy specimens obtained from Mexican patients. Each case was classified histologically into one of the following groups: (1) invasive adenocarcinoma (N = 21), (2) high-grade dysplasia (carcinoma in situ) (N = 2), (3) low-grade dysplasia (N = 4), hyperplasia (4) (N = 15), and (5) chronic cholecystitis (N = 10). Significant differences (P < 0.05) were identified among the five histopathologic groups in the proportion of epithelial cells demonstrating immunoreactivity with MAbs to Lewisb; Lewis(a); sialylated Lewis(a); sialylated Lewis(a) and Lewis(a); Y antigen; H antigen; X antigen; X-like antigen; 200-kDa protein of CEA; 180-, 160-, 50-, 40-kDa proteins of CEA; 30- to 37-kDa protein; and an undefined antigen identified by MAb 99-57, with invasive carcinoma more frequently being positive as compared to nonneoplastic (hyperplasia, chronic cholecystitis) epithelium. Significant differences were also observed among the five histopathologic groups (P < or = 0.0005) in the proportion of epithelial cells demonstrating immunoreactivity with MAbs to Y antigen and the 20- to 50-kDa glycoprotein. However, with these two antibodies immunoreactivity was more frequently found in nonneoplastic epithelium rather than in invasive carcinomas. No significant differences in immunoreactivity were detected among the different histologic groups with MAb to blood group B antigen, types 1 and 2. This study demonstrates that cellular antigens are both developed and lost during the process of neoplastic transformation in the gallbladder.(ABSTRACT TRUNCATED AT 250 WORDS)

A prospective study of pulmonary function and gas exchange following liver transplantation

Pulmonary function and gas exchange were prospectively studied in 95 patients before and 9 to 15 months following liver transplantation. Pretransplant, the most common PF abnormality was impaired efficiency of gas exchange as measured by Dss. As a group, the mean Dss was 78.0 +/- 16.6 percent predicted and was found to be less than 80 percent predicted in 50 patients. As a group, patients with the most severe liver diseases clinically (Child's C classification) had the lowest mean Dss pretransplant. Posttransplant, three findings were of clinical importance: PaCO2 significantly improved posttransplantation, suggesting a resolution of pretransplant respiratory alkalosis. Expiratory airflow obstruction, measured by a change in the FEV1/FVC, was extremely uncommon posttransplant. Mean Dss improved significantly in patients with Child's C severity of liver disease. The most frequent deteriorations in Dss statistically were associated with posttransplant thoracotomy, ARDS, nonspecific pneumonitis, significant pleural effusions and hepatic retransplantation.

Two antigens detected on human ocular melanomas with the mouse monoclonal antibodies 2/10SN and 10/12SN

Seven human ocular melanoma cell lines were established in vitro and 3 of these, GU-4, LLN-40 and its subline C17-11, were characterized. Mice were immunized with these ocular melanoma cell lines, and 2 hybridomas producing monoclonal IgG1 antibodies (MAb) were produced. MAb 2/10SN recognizes a 44-kDa monomeric protein, whereas MAb 10/12SN reacts with an 83/65-kDa heterodimeric protein. These melanoma-associated antigens (MAA) are detected at high concentrations in the cytoplasm of ocular melanoma cells. However, cell-surface labelling techniques suggest that these MAA are also associated with the cell-surface membrane. These 2 ocular MAA are also expressed by several skin melanoma cell lines. Immunohistochemical studies have localized these antigens to ocular and skin melanomas, to sweat ducts and basal squamous cells in normal skin, with limited expression in several other normal tissues and some carcinomas. Biodistribution studies in nude mice with human ocular melanomas have demonstrated good localization of 125I-labeled MAb 2/10SN at the tumor sites. Therefore, these 2 MAbs, 2/10SN and 10/12SN, recognize MAA which appear to be unique and may prove useful for imaging purposes.

Cutaneous responses to vasoactive intestinal polypeptide in chronic idiopathic urticaria

Cutaneous wheal and flare responses to increasing concentrations of calcitonin gene-related peptide, substance P, neurokinin A, vasoactive intestinal polypeptide (VIP), compound 48/80, and phosphate-buffered saline were measured in 10 patients with chronic idiopathic urticaria and 10 healthy controls. A significant increase in VIP-induced wheal, but not flare or cutaneous blood flow, was seen in urticarial patients compared with controls (p less than 0.001). No significant differences in responses to other tested compounds were found between these groups. These data point to an increased sensitivity of microvasculature to VIP in patients with chronic idiopathic urticaria.

Use of bacterial trpE fusion vectors to express and characterize the bovine immunodeficiency-like virus core protein

The gag coding region from Bovine Immunodeficiency-like Virus (BIV) was cloned into E. coli and expressed as a bacterial fusion protein. Six different clones spanning various regions of the gag open reading frame were generated. The resulting fusion proteins were expressed at high concentrations and readily purified. A panel of bovine immune sera specifically recognized the recombinant Gag proteins, as did immune sera from animals infected or immunized with lentiviruses related to BIV, such as Equine Infectious Anemia Virus (EIAV) and Human Immunodeficiency Virus (HIV). Analysis of the deletion clones, using the bovine immune sera panel, enabled us to identify at least one major epitope which was specifically recognized by all bovine sera examined. The ease of expression, purification, and specificity of these fusion proteins should enable a thorough study of the epidemiology of BIV infection.

Interaction of subtype-selective antagonists with alpha 1-adrenergic receptor-mediated second messenger responses in rat brain

The selective antagonists (+)-niguldipine and 5-methylurapidil (5-MU) were used to more clearly identify the alpha 1-adrenergic receptor subtypes involved in second messenger responses in slice and culture preparations of rat brain. The alpha 1-adrenergic receptor activating [3H]inositol phosphate (InsP) formation in neocortical and hippocampal slices appeared to have mixed characteristics. Although the low potency of (+)-niguldipine indicated involvement of the alpha 1B subtype, 5-MU had an alpha 1A-like potency at this subtype. (+)-Niguldipine did not inhibit the alpha 1 receptor-mediated potentiation of the cAMP response to either isoproterenol or adenosine in cortical slices, even at high concentrations. 5-MU inhibited both cAMP responses, although this inhibition appeared non-competitive. Thus, these receptors are clearly different from those mediating InsP formation. In primary glial cultures, (+)-niguldipine also had a low potency in blocking norepinephrine-stimulated [3H]InsP formation, consistent with involvement of the alpha 1B subtype. However, both 5-MU and WB 4101 had high potencies in blocking this response, suggesting involvement of the alpha 1A subtype. Inactivation of the alpha 1B subtype by pretreatment of cultures with chloroethylclonidine did not increase the potencies of any of these antagonists. The inhibition by 5-MU and WB 4101 was competitive in both control and chloroethylclonidine-pretreated cultures, whereas the inhibition by (+)-niguldipine was primarily noncompetitive. The use of these more selective antagonists shows that the current alpha 1A/alpha 1B subclassification scheme is inadequate to identify the receptors mediating these responses. None of the responses were blocked by (+)-niguldipine with the high potency expected at the alpha 1A subtype, although all InsP responses were blocked by 5-MU with a relatively high (alpha 1A-like) potency. In addition, very low affinity and noncompetitive effects of (+)-niguldipine were observed. These data raise the possibility of additional subtypes of alpha 1-adrenergic receptors or as yet unidentified functional interactions between known subtypes.