From bench to bedside: initial experience with the Primus drug-coated balloon catheter.

AIM: Drug-coated balloon (DCB) technology has emerged as a promising therapy particularly in the treatment of coronary in-stent restenosis. Although a variety of devices are available for clinical use, clinical outcomes have been variable and scope for significant improvement exists. METHODS: In a preclinical study, a total of 10 juvenile healthy farm pigs underwent catheter-based DCB deployment in coronary arteries with angiographic and pathological follow-up at 7 or 28 days. Animals were randomly allocated to the PRIMUS or Dior® DCB (N.=10 per group) and evaluated by histopathology and morphometric analysis. In a first-in-man clinical study a total of 19 consecutive patients presenting with restenosis within drug-eluting stents were treated with the PRIMUS DCB. Clinical follow-up was performed out to 6 months. RESULTS: Neointimal thickness was similar between the PRIMUS and Dior® DCB groups, while fibrin deposition and inflammation were more sustained in the PRIMUS group at 28 days. In 19 consecutive patients presenting with in-stent restenosis of drug-eluting stents, treatment with the PRIMUS DCB catheter resulted in high procedural efficacy. There were no adverse clinical events observed out to 6 months. CONCLUSION: The PRIMUS DCB demonstrates high preclinical safety and excellent acute performance and safety. Further studies are needed to delineate the relative merits of this novel DCB compared to other devices.

Two novel routes of transporter associated with antigen processing (TAP)-independent major histocompatibility complex class I antigen processing.

Jaw1 is an endoplasmic reticulum (ER) resident protein representative of a class of proteins post translationally inserted into membranes via a type II membrane anchor (cytosolic NH2 domain, lumenal COOH domain) in a translocon-independent manner. We found that Jaw1 can efficiently deliver a COOH-terminal antigenic peptide to class I molecules in transporter associated with antigen processing (TAP)-deficient cells or cells in which TAP is inactivated by the ICP47 protein. Peptide delivery mediated by Jaw1 to class I molecules was equal or better than that mediated by the adenovirus E3/19K glycoprotein signal sequence, and was sufficient to enable cytofluorographic detection of newly recruited thermostabile class I molecules at the surface of TAP-deficient cells. Deletion of the transmembrane region retargeted Jaw1 from the ER to the cytosol, and severely, although incompletely, abrogated its TAP-independent peptide carrier activity. Use of different protease inhibitors revealed the involvement of a nonproteasomal protease in the TAP-independent activity of cytosolic Jaw1. These findings demonstrate two novel TAP-independent routes of antigen processing; one based on highly efficient peptide liberation from the COOH terminus of membrane proteins in the ER, the other on delivery of a cytosolic protein to the ER by an unknown route.

Gamma-glutamyl transpeptidase in brain capillaries: possible site of a blood-brain barrier for amino acids.

A fraction containing capillaries and rich in gamma-glutamyl transpeptidase was isolated from homogenates of bovine brain cortex by density gradient centrifugation. The enzyme was localized in the endothelial cells by a histochemical procedure. gamma-Glutantyl transpeptidase may function in the transfer of some amino acids across the blood-brain barrier.

Tumor growth inhibition induced in a murine model of human Burkitt's lymphoma by a proteasome inhibitor.

Cell growth and viability are dependent on the function of the multicatalytic proteinase complex (proteasome), a multisubunit particle that affects progression through the mitotic cycle by degradation of cyclins. Exposure of rodent fibroblasts and human lymphoblasts in culture to benzyloxycarbonyl-leucyl-leucyl-phenylalaninal (Z-LLF-CHO), a cell-permeable peptidyl aldehyde inhibitor of the chymotrypsin-like activity of the proteasome, resulted in the induction of apoptosis in a rapid, dose-dependent fashion. Fibroblasts transformed with ras and myc, lymphoblasts transformed by c-myc alone, and a Burkitt's lymphoma (BL) cell line that overexpresses c-Myc were up to 40-fold more susceptible to apoptosis than were either primary rodent fibroblasts or immortalized nontransformed human lymphoblasts, respectively. To determine whether such preferential apoptosis could impact upon tumor growth in vivo, toxicological studies were performed in mice with severe combined immunodeficiency and showed that mice tolerated single interscapular doses of Z-LLF-CHO without unacceptable toxicity. Severe combined immunodeficient mice bearing s.c. BL tumors in the flank were treated interscapularly with Z-LLF-CHO or a comparable dose of the peptidyl alcohol (Z-LLF-OH), which does not induce proteasome inhibition or apoptosis. Single doses of Z-LLF-CHO induced statistically significant (P < 0.0001) early tumor regression and a significant (P < 0.0001) delay in tumor progression. Analysis of tumor specimens revealed increased apoptosis in BL tumors from mice treated with Z-LLF-CHO. These results, showing a 42% tumor growth delay, indicate that proteasome inhibitors have the potential of curbing the growth of a c-myc-related tumor.

Phase Ia/Ib trial of bispecific antibody MDX-210 in patients with advanced breast or ovarian cancer that overexpresses the proto-oncogene HER-2/neu.

PURPOSE: MDX-210 is a bispecific antibody that binds simultaneously to type I Fc receptors for immunoglobulin G (IgG) (Fc gamma RI) and to the HER-2/neu oncogene protein product. MDX-210 effectively directs Fc gamma RI-positive effector cells such as monocytes and macrophages to phagocytose or kill tumor cells that overexpress HER-2/neu. The goals of this phase Ia/Ib trial were to determine the maximum-tolerated dose (MTD) and/or the optimal biologic dose (OBD) of MDX-210. PATIENTS AND METHODS: Patients with advanced breast or ovarian cancer that overexpressed HER-2/neu were eligible for treatment. Cohorts of three patients received a single intravenous (IV) infusion of MDX-210 at increasing dose levels from 0.35 to 10.0 mg/m2. RESULTS: Treatment was well tolerated, with most patients experiencing transient grade 1 to 2 fevers, malaise, and hypotension only. Two patients experienced transient grade 3 hypotension at 10.0 mg/m2. Transient monocytopenia and lymphopenia developed at 1 to 2 hours, but no other hematologic changes were observed. Doses of MDX-210 > or = 3.5 mg/m2 saturated > or = 80% of monocyte Fc gamma RI and produced peak plasma concentrations > or = 1 microgram/mL, which is greater than the concentration for optimal monocyte/macrophage activation in vitro. Elevated plasma levels of the monocyte products tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), granulocyte colony-stimulating factor (G-CSF), and neopterin were observed with maximal levels at doses > or = 7.0 mg/m2. Localization of MDX-210 in tumor tissue was demonstrated in two patients. One partial and one mixed tumor response were observed among 10 assessable patients. CONCLUSION: MDX-210 is immunologically active at well-tolerated doses. The MTD and OBD is 7 to 10 mg/m2.

Soluble metalloendopeptidase from rat brain: action on enkephalin-containing peptides and other bioactive peptides.

A soluble metalloendopeptidase identified in rat brain, preferentially cleaves bonds in peptides having hydrophobic amino acid residues in the P1, P2, and P3' positions. (The nomenclature of T. Schechter and A. Berger is used to describe the interaction between enzyme and substrate. The amino acid residues in the substrate are designated as P1, P2, P3 etc. in the N-terminal direction and P1', P2', P3' etc. in the C-terminal direction from the bond undergoing cleavage. The corresponding subsites in the enzyme are identified by the letter S.) The degradation of a series of biologically active peptides and their affinity toward the enzyme was studied. Dynorphin-(1-8), alpha-neo-endorphin, and beta-neo-endorphin are rapidly hydrolyzed to form leu-enkephalin, whereas bovine adrenal medulla dodecapeptide is hydrolyzed to form met-enkephalin. The enzyme, however, does not cleave a larger precursor molecule of metenkephalin, such as bovine adrenal medulla docosapeptide. Several other bioactive peptides are also cleaved at sites consistent with our previously reported specificity studies. Met- and leu-enkephalin are resistant to hydrolysis. The binding affinity [as expressed by inhibitory constant (Ki) or Michaelis-Menten constant (Km) values] of several bioactive peptides such as dynorphin-(1-8), beta-neo-endorphin, neurotensin, angiotensin I, and bradykinin was found to be in the micromolar range. These peptides were also rapidly hydrolyzed by the enzyme, showing, as a result, high specificity constants (kcat/Km values). The highest enzyme activity was found in brain, testis, and in the anterior and posterior lobes of the pituitary, while the activity in such tissues as spleen, liver, kidney, lung, adrenals, and thyroid amounted to only 10-20% of that found in brain. This distribution of enzyme activity, together with its preference for oligopeptides as substrates, its ability to generate leu- and met-enkephalin from several larger peptide precursors, and its affinity toward several other bioactive peptides, suggests that the enzyme functions in the metabolism of neuropeptides.

Peptide-degrading enzymatic activities in GH3 cells and rat anterior pituitary homogenates.

The activities of a number of peptide-degrading enzymes were compared in homogenates of GH3 cells and rat anterior pituitaries. The enzymes studied were prolyl endopeptidase (EC 3.4.21.26), a soluble metalloendopeptidase, pyroglutamyl peptide hydrolase (EC 3.4.11.8), a multicatalytic protease complex, cathepsin B (EC 3.4.22.1), cathepsin D (EC 3.4.23.5), aminopeptidase (EC 3.4.11.2), and a membrane-bound neutral metalloendopeptidase (EC 3.4.24.11). Specific substrates were used to measure the activities, and active-site-directed inhibitors were used to verify the identities of the enzymes studied. Of the two lysosomal enzymes studied, cathepsin B, the enzyme with the highest activity in both preparations, had 5 times the activity in GH3 cell homogenates as in anterior pituitary homogenates. Cathespin D had a somewhat higher activity in the anterior pituitary homogenates than in the GH3 cell homogenates. Soluble metalloendopeptidase and prolyl endopeptidase, both cytoplasmic enzymes, had about twice the activity in GH3 cell homogenates as in anterior pituitary homogenates. Membrane-bound neutral metalloendopeptidase in the GH3 cell homogenates had 25% of the activity of the anterior pituitary homogenates. Of the two TRH-degrading enzymes, the activity of prolyl endopeptidase in GH3 cell homogenates was about 25 times higher than that of pyroglutamyl peptide hydrolase. Since the secretory function of the pituitary is in part controlled by neuropeptides, the knowledge of the enzyme profiles of the GH3 cells and the anterior pituitary should be of value in studying the metabolism of neuropeptides and peptide hormones in these systems.

Effects of a metalloendopeptidase-24.15. Inhibitor on renal hemodynamics and function in rats.

N-[1-(R,S)-carboxyl-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate (cFP-AAF-pAB), an active-site-directed inhibitor of metalloendopeptidase-24.15, has been shown to lower blood pressure, increase cardiac output and renal blood flow, and potentiate the intravenous bradykinin-induced vasodepressor response. Because in vivo cFP-AAF-pAB can be converted to N-[1-(R,S)-carboxyl-3-phenylpropyl]-Ala-Ala (a compound with angiotensin converting enzyme inhibitory activity) by metalloendopeptidase-24.11, it is possible that some of its effects are due to angiotensin converting enzyme inhibition. In the present study, we questioned (1) whether cFP-AAF-pAB inhibits angiotensin converting enzyme in vivo and (2) whether cFP-AAF-pAB has renal effects that are independent of its conversion to an angiotensin converting enzyme inhibitor. cFP-AAF-pAB alone (3 mumol in 300 microL per rat) almost abolished the blood pressure response to angiotensin I, suggesting that in vivo it inhibits angiotensin converting enzyme. In rats pretreated with a high dose of enalaprilat (1 mg/kg), cFP-AAF-pAB had no further effect on blood pressure, renal blood flow, or potentiation of the vasodepressor response to bradykinin but still increased glomerular filtration rate by 44 +/- 9% (P < .01); urine volume increased by 118 +/- 10% (P < .001), urinary sodium excretion by 230 +/- 31% (P < .001), urinary potassium excretion by 68 +/- 14% (P < .01), and urinary cyclic GMP by 55 +/- 18% (P < .01). All of these changes were significant compared with enalaprilat/vehicle-treated rats. Fractional excretion of sodium and potassium did not differ from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultra-high throughput screen of two-million-member combinatorial compound collection in a miniaturized, 1536-well assay format.

Results of a complete survey of the more than 2-million-member Pharmacopeia compound collection in a 1536-well microvolume screening assay format are reported. A complete technology platform, enabling the performance of ultra-high throughput screening in a miniaturized 1536-well assay format, has been assembled and utilized. The platform consists of tools for performing microvolume assays, including assay plates, liquid handlers, optical imagers, and data management software. A fluorogenic screening assay for inhibition of a protease enzyme target was designed and developed using this platform. The assay was used to perform a survey screen of the Pharmacopeia compound collection for active inhibitors of the target enzyme. The results from the survey demonstrate the successful implementation of the ultra-high throughout platform for routine screening purposes. Performance of the assay in the miniaturized format is equivalent to that of a standard 96-well assay, showing the same dependence on kinetic parameters and ability to measure enzyme inhibition. The survey screen identified an active class of compounds within the Pharmacopeia compound collection. These results were confirmed using a standard 96-well assay.

Endopeptidase 24.15 inhibition and opioid antinociception.

Whereas endopeptidase 24.11 cleaves the Gly-Phe bond in both Met- and Leu-enkephalin, endopeptidase 24.15 rapidly converts dynorphin A1-8, alpha and beta-neoendorphin into Leu-enkephalin, and Met-enkephalin-Arg6-Gly7-Leu8 (MERGL) into Met-enkephalin. Inhibitors of both endopeptidase 24.11 and endopeptidase 24.15 each produce antinociception, and inhibitors of endopeptidase 24.11 increase the magnitude of enkephalin antinociception. The present study compared the central antinociceptive effect of an inhibitor of endopeptidase 24.15, N-[1-(R-S)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate (cFP-AAF-pAB) with one of endopeptidase 24.11 N-[1-(RS)-carboxy-3-phenylpropyl]-Phe-p-aminobenzoate (cFP-F-pAB) upon central opioid antinociception induced by MERGL, metenkephalin and dynorphin A1-8. cFP-AAF-pAB, but not cFP-F-pAB increased MERGL antinociception on the tail-flick and jump tests. In contrast, cFP-F-pAB, but not cFP-AAF-pAB increased met-enkephalin antinociception. Whereas central dynorphin A1-8 failed to induce antinociception itself, co-administration of cFP-AAF-pAB and dynorphin A1-8 increased nociceptive thresholds. This effect was not accompanied by motor dysfunction, but was blocked by systemic pretreatment with naloxone or central pretreatment with naltrexone or nor-binaltorphamine, but not beta-funaltrexamine. These data indicate that endopeptidase 24.15 may be responsible for the degradation of specific opioid peptides (e.g., MERGL, dynorphin), and that this process may prevent the full expression of their antinociceptive properties.

Evidence that enzymatic conversion of N-[1(R,S)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate, a specific inhibitor of endopeptidase 24.15, to N-[1(R,S)-carboxy-3-phenylpropyl]-Ala-Ala is necessary for inhibition of angiotensin converting enzyme.

N-[1(R,S)-Carboxy-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate (cFP-AAF-pAB) is a potent, substrate-related, specific inhibitor of endopeptidase 24.15, an enzyme involved in the metabolism of bioactive peptides including bradykinin, neurotensin, and proenkephalin, and prodynorphin-derived enkephalin precursors. The observation that this inhibitor causes a pronounced decrease in blood pressure after intravenous infusion into normotensive rats posed the question of the mechanism of this hypotensive response. It was suggested previously that cFP-AAF-pAB is an inhibitor of angiotensin converting enzyme (ACE) and that this function can account for the hypotensive response to the inhibitor. We present here evidence that cFP-AAF-pAB has no intrinsic ACE-inhibitory activity. The previously observed inhibition is shown to be dependent on cleavage of the Ala-Phe bond in the inhibitor by endopeptidase 24.11 (enkephalinase, EC 3.4.24.11), a contaminant of some ACE preparations.

Immunocytochemical localization of endopeptidase 24.15 in rat brain.

Endopeptidase 24.15 (EC 3.4.24.15; EP 24.15), a zinc-metalloendopeptidase highly active in rat testes, brain and pituitary, converts some prodynorphin- and proenkephalin-derived oligopeptides into the corresponding enkephalins and degrades a variety of bioactive peptides including bradykinin, neurotensin, and both angiotensin I and II. The immunocytochemical localization of the enzyme was studied in rat brain using a polyclonal antibody raised in rabbits against a homogeneous preparation of the enzyme isolated from rat testes. The distribution of EP 24.15 immunoreactivity in the brain was widespread, being present in both neurons and glial cells. Surprisingly, however, staining was predominantly nuclear, and not cytoplasmic as expected based on the biochemical demonstration that EP 24.15 activity is predominantly associated with the soluble protein fraction of brain homogenates. Cytoplasmic staining was detected in large neurons but was less intense than the nuclear staining. The highest density of EP 24.15-staining was detected in nuclei of cerebellar Purkinje cells and in hippocampal dentate gyrus cells. High levels of immunoreactivity were also noted in brain areas which contain peptides known to be substrates of the enzyme in vitro. This localization supports a role for EP 24.15 in neuropeptide metabolism, but also suggests an as yet undefined role in nuclear function.

gamma-Glutamyl DOPA and gamma-glutamyl dopamine: effect on plasma glucose levels.

gamma-Glutamyl-L-3,4-dihydroxyphenylalanine (gamma-glutamyl DOPA) and gamma-glutamyldopamine (gamma-glutamyl DA) are kidney specific prodrugs. Their effect on plasma glucose levels in the rat was compared to that of L-DOPA and dopamine (DA) after a 30 min intravenous infusion. L-DOPA and DA induced hyperglycemia after 15 min of druginfusion. A more marked and protracted elevation of plasma glucose was observed after infusion of gamma-glutamyl DA. By gamma-glutamyl DOPA had no effect on plasma glucose levels in spite of the high accumulation of DA in the pancreas after this prodrug. Of the various dopamine produrgs studied only gamma-glutamyl DOPA was not hyperglycemic in doses that are known to increase renal plasma flow in the rat. A simplified new procedure for the synthesis of gamma-glutamyl DA is described.

Intracerebroventricular infusion of inhibitors of endopeptidase-24.11 ('enkephalinase') increases the spontaneous firing frequency of an identifiable set of cells in the substantia nigra.

The effect of inhibitors of the membrane-bound metalloendopeptidase-24.11 ('enkephalinase') on the activity of electrophysiologically identifiable neurons in the substantia nigra is described. Dopaminergic and non-dopaminergic cells were examined. Cells were classified by their responses to striatal stimulation. Only those cells in which the stimulation evoked excitation (alone or mixed with inhibition) responded to the inhibitors. Those cells in which the evoked response was only inhibition did not respond to the drugs. Infusion of 1 mumol of N-[1-(R,S)-carboxy-2-phenyl-ethyl]Phe-pAB (CPAB), 1 or 2 mumol of N-[1-(R,S)-carboxy-3-phenylpropyl]Phe-pAB (CPPAB) into the lateral ventricle produced statistically significant increases (pre- to post-drug treatment) in the spontaneous activity of cells exhibiting excitatory evoked responses: average increases were 33.3%. The increase in spontaneous activity reached an apparent maximum 20 min after the end of the infusion. The increased firing frequency was shown to result from the inhibition of the enzyme, rather than a non-specific effect, as the infusion of 2 mumol of N-[1-(R,S)-carboxy-2-phenyl-ethyl]Leu-pAB, an inhibitor structurally related to CPAB and CPPAB yet two orders of magnitude less potent, was without effect on the activity of nigral neurons. The inhibition of the enzyme by 1 mumol CPAB was verified through in vitro assay. We hypothesize that inhibition of the enzyme enhances peptide-modulated (tachykinin and/or enkephalin) excitation in select neurons of the substantia nigra.

Inhibitors of an enkephalin degrading membrane-bound metalloendopeptidase: analgesic properties and effects on striatal enkephalin levels.

Intraperitoneal administration of N-[1-(R,S)-carboxy-2-phenylethyl-Phe-p-aminobenzoate, synthesized in this laboratory as a potent inhibitor of membrane-bound metalloendopeptidase (EC 3.4.24.11) caused a prolonged but weak analgesic effect on rats as measured by the tail flick test. It also caused a transitory but significant increase in striatal [Leu5]- and [Met5]enkephalin levels 3 h, after administration. Analogs of the inhibitor in which the phenylalanyl residue was replaced by an alanyl or glycyl residue also elicited prolonged analgesic responses although their inhibitory potencies were 75 and more than 1500 times lower respectively. The glycine containing derivative did not alter striatal enkephalin levels 3 h, after administration. The data suggest that inhibition of the metalloendopeptidase decreases the rate of degradation of endogenous enkephalins, however the analgesic properties of the inhibitors do not seem to be related to their inhibitory potencies. Factors other than changes in striatal enkephalin levels may contribute to the analgesic effect of the three N-carboxyphenylethyl derivatives.

Degradation of luteinizing hormone-releasing hormone (LHRH) by brain prolyl endopeptidase with release of des-glycinamide LHRH and glycinamide.

A highly purified preparation of rabbit brain prolyl endopeptidase cleaved the decapeptide luteinizing hormone-releasing hormone (LHRH) at the ProGly . NH2 bond leading to the release within 1-3 h incubation at 37 degrees C of des-glycinamide LHRH and glycinamide. Evidence for this site of cleavage was obtained by the detection of glycinamide or glycine and groups by a microdanyslation procedure, and by separation of the breakdown products by high performance liquid chromatography (HPLC) on a revers phase C-18 column. Incubation led to the appearance of two new peaks as detected by HPLC one of which was collected and shown to have the composition consistent with des-glycinamide LHRH. The other peak ran in the position identical to that of authentic glycinamide. Results suggest that prolyl endopeptidase could play a role in the inactivation of LHRH in vivo.

Increases in opioid-mediated swim antinociception following endopeptidase 24.15 inhibition.

The duration of action and potency of endogenous opioid peptides are limited by proteolytic enzymes such as endopeptidases 24.11 and 24.15. Whereas endopeptidase 24.11 cleaves enkephalin pentapeptides, endopeptidase 24.15 degrades longer-chained opioids including dynorphin A1-8 and met-enkephalin-Arg6-Gly7-Leu8 (MERGL). Inhibitors of endopeptidase 24.11 and 24.15 both increase basal nociceptive thresholds and respective forms of opioid antinociception. Acute exposure to certain environmental stressors can produce antinociception which is opioid mediated; inhibitors of endopeptidase 24.11 potentiate this effect. The present study evaluated whether central administration of a selective inhibitor of endopeptidase 24.15, N-[1-(RS)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate (cFP-AAF-pAB) increased antinociception following intermittent cold-water swims (ICWS) in rats. cFP-AAF-pAB (0.25-25 nmol, ICV) dose-dependently increased ICWS antinociception on the tail-flick and jump tests without affecting basal nociceptive thresholds. The opioid mediation of ICWS antinociception was confirmed by significant reductions in this response following naloxone. These data indicate that longer-chained endogenous opioid peptides participate in the antinociception induced by ICWS.

Central administration of the endopeptidase 24.15 inhibitor cFP-AAF-pAB suggests dynorphin as the endogenous ligand underlying behavioral effects of milk in the fetal rat.

Intraoral infusion of milk to the rat fetus promotes opioid activity that results in reduced responsiveness in a behavioral bioassay involving perioral cutaneous stimulation. Intracisternal administration of cFP-AAF-pAB, an inhibitor of endopeptidase 24.15, prolonged the opioid activity induced by milk infusion. Treatment with the selective kappa opioid antagonist nor-binaltorphimine blocked the effect of cFP-AAF-pAB on milk-induced opioid activity, but treatment with the mu antagonist CTOP or the delta antagonist naltrindole did not. These findings imply that milk may exert its effect on fetal behavior by increasing levels of dynorphin in the fetal central nervous system.

Screening aspartyl proteases with combinatorial libraries.

Large numbers of pharmaceutically relevant low-molecular weight compounds can now be synthesized using combinatorial methods. Screening these large libraries of compounds requires high throughput assays. These methods are utilized to search for inhibitors of the aspartyl proteases, plasmepsin II and cathepsin D. Plasmepsin II, a protease found in the malaria parasite, hydrolyzes human hemoglobin, the nutrient source for the parasite and is a new target for anti-malaria therapy. Cathepsin D may be involved in many biological processes and inhibitors would help to clarify the role of cathepsin D in these processes. Plasmepsin II and cathepsin D are approximately 35% identical in amino acid sequence. Therefore, a comparison of the screening results of these two enzymes will be very useful in determining each enzyme's specificity and demonstrating the power of utilizing encoded combinatorial libraries.

Capecitabine: nursing implications of a new oral chemotherapeutic agent.

PURPOSE/OBJECTIVES: To describe the new oral chemotherapeutic agent capecitabine (Xeloda, Roche Laboratories Inc., Nutley, NJ) and key concepts driving its development and to delineate the nursing impact of patient-administered, home-based chemotherapies. DATA SOURCES: Published papers, investigational materials, package inserts, and clinical experience. DATA SYNTHESIS: Capecitabine recently was approved to treat metastatic breast cancer refractory to paclitaxel and anthracycline-containing regimens. Efficacy has been demonstrated. However, although the current regimen is well-tolerated, > or = 40% of patients require dose modification because of grade 2 or greater toxicity, usually hand-foot syndrome or gastrointestinal symptoms. CONCLUSIONS: Capecitabine frees nurses from infusion-related workload, allowing and demanding a new type and level of patient education. Such education emphasizes compliance with the treatment plan and prevention, timely recognition, and management of toxicities. These practice changes also challenge nurses to advocate for reimbursement of educational practices. IMPLICATIONS FOR NURSING PRACTICE: Oncology nurses will play more of a central role as use of patient-administered, home-based therapies increases. Nurses must enhance their patient-education and telephone symptom-management skills and help to secure reimbursement for such activities.