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In recent years, a novel treatment method for cancer has emerged, which is based on the starvation of tumors of amino acids like arginine. The deprivation of arginine in serum is based on enzymatic degradation and can be realized by arginine deaminases like the l-amino acid oxidase found in the ink toxin of the sea hare Aplysia punctata . Previously isolated from the ink, the l-amino acid oxidase was described to oxidate the essential amino acids l-lysine and l-arginine to their corresponding deaminated alpha-keto acids. Here, we present the recombinant production and functionalization of the amino acid oxidase Aplysia punctata ink toxin (APIT). PEGylated APIT (APIT-PEG) increased the blood circulation time. APIT-PEG treatment of patient-derived xenografted mice shows a significant dose-dependent reduction of tumor growth over time mediated by amino acid starvation of the tumor. Treatment of mice with APIT-PEG, which led to deprivation of arginine, was well tolerated.

Background: Cancer cachexia is associated with reduced body weight, appetite and quality of life (QOL) with no approved treatments. Growth hormone secretagogues like macimorelin have potential to mitigate these effects., Methods: This pilot study assessed the safety and efficacy of macimorelin for 1 week. Efficacy was defined a priori as 1-week change in body weight (≥0.8 kg), plasma insulin-like growth factor (IGF)-1 (≥50 ng/mL) or QOL (≥15%). Secondary outcomes included food intake, appetite, functional performance, energy expenditure and safety laboratory parameters. Patients with cancer cachexia were randomized to 0.5 or 1.0 mg/kg macimorelin or placebo; outcomes were assessed non-parametrically., Results: Participants receiving at least one of either macimorelin dose were combined (N = 10; 100% male; median age = 65.50 ± 2.12) and compared with placebo (N = 5; 80% male; median age = 68.00 ± 6.19). Efficacy criteria achieved: body weight (macimorelin N = 2; placebo N = 0; P = 0.92); IGF-1 (macimorelin N = 0; placebo N = 0); QOL by Anderson Symptom Assessment Scale (macimorelin N = 4; placebo N = 1; P = 1.00) or Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F; macimorelin N = 3; placebo N = 0; P = 0.50). No related serious or non-serious adverse events were reported. In macimorelin recipients, change in FACIT-F was directly associated with change in body weight (r = 0.92, P = 0.001), IGF-1 (r = 0.80, P = 0.01), and caloric intake (r = 0.83, P = 0.005), and inversely associated with change in energy expenditure (r = -0.67, P = 0.05)., Conclusions: Daily oral macimorelin for 1 week was safe and numerically improved body weight and QOL in patients with cancer cachexia compared with placebo. Longer term administration should be evaluated for mitigation of cancer-induced reductions in body weight, appetite and QOL in larger studies., (© 2023 Aeterna Zentaris GmbH. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Background: Current drugs for epilepsy affect seizures, but no antiepileptogenic or disease-modifying drugs are available that prevent or slow down epileptogenesis, which is characterized by neuronal cell loss, inflammation and aberrant network formation. Ghrelin and ghrelin receptor (ghrelin-R) agonists were previously found to exert anticonvulsant, neuroprotective and anti-inflammatory effects in seizure models and immediately after status epilepticus (SE). Therefore, the aim of this study was to assess whether the ghrelin-R agonist macimorelin is antiepileptogenic in the pharmacoresistant intrahippocampal kainic acid (IHKA) mouse model., Methods: SE was induced in C57BL/6 mice by unilateral IHKA injection. Starting 24 h after SE, mice were treated intraperitoneally with macimorelin (5 mg/kg) or saline twice daily for 2 weeks, followed by a 2-week wash-out. Mice were continuously electroencephalogram-monitored, and at the end of the experiment neuroprotection and gliosis were assessed., Results: Macimorelin significantly decreased the number and duration of seizures during the treatment period, but had no antiepileptogenic or disease-modifying effect in this dose regimen. While macimorelin did not significantly affect food intake or body weight over a 2-week treatment period, its acute orexigenic effect was preserved in epileptic mice but not in sham mice., Conclusions: While the full ghrelin-R agonist macimorelin was not significantly antiepileptogenic nor disease-modifying, this is the first study to demonstrate its anticonvulsant effects in the IHKA model of drug-refractory temporal lobe epilepsy. These findings highlight the potential use of macimorelin as a novel treatment option for seizure suppression in pharmacoresistant epilepsy., (© 2021 European Academy of Neurology.)

Purpose: The test with the highest diagnostic accuracy for diabetes insipidus is copeptin measurement after hypertonic saline infusion. However, the procedure is cumbersome and unpleasant due to rapid sodium increase. An oral stimulation test would be highly desirable. Macimorelin, an oral ghrelin agonist, is a newly approved diagnostic test for growth hormone (GH) deficiency, but its effects on copeptin/vasopressin are unknown and the effects on other pituitary hormones only scarcely investigated., Methods: In this prospective, interventional, proof-of-concept study Copeptin and anterior pituitary hormones were measured in 28 healthy volunteers on two test days at baseline, 30, 45, 60, 90 and 120 min after a single dose of macimorelin (first visit: 0.5 mg/kg, second visit: 0.75 mg/kg)., Results: Baseline copeptin levels were 5.26 pmol/L [1.57, 6.81] and did not change after macimorelin intake (0.5 mg/kg: maximal median change 0.40 [- 0.49, 0.65] pmol/L, p = 0.442; 0.75 mg/kg: - 0.13 [- 0.45, 0.17] pmol/L, p = 0.442. Median GH levels increased from 3.67 mU/L with a maximal median change of 94.66 [IQR 56.5; 110.96] mU/L, p < 0.001. No effect was seen on cortisol, ACTH, LH and FSH levels. Prolactin (max. median change 100 [2.5; 146.5] mU/L, p = 0.004) and free thyroxine (fT4) (0.5 [0.2; 0.8] pmol/L, p < 0.001) increased, whereas TSH decreased (- 0.18 [- 0.22, - 0.09] mU/L, p < 0.001)., Conclusion: We confirm an increase of GH upon macimorelin in healthy volunteers. However, macimorelin did not stimulate copeptin and therefore does not provide an oral test alternative for the diagnosis of diabetes insipidus. Additionally, a stimulatory effect was seen for prolactin and fT4, but not for ACTH and gonadotropic hormones., Registration: The trial was registered on ClinicalTrials.gov (NCT03844217) on February 18, 2019., (© 2021. The Author(s).)

Macimorelin is an orally active growth hormone secretagogue indicated for the diagnosis of adult growth hormone deficiency. The primary objective of this study was to evaluate the effect of macimorelin on the baseline and placebo-corrected mean QT interval using Fridericia's formula (ΔΔQTcF). Secondary objectives were to determine QTcF for moxifloxacin; evaluate the effects of macimorelin on other cardiac intervals (PR, QRS, RR), heart rate, and electrocardiogram morphology parameters; characterize pharmacokinetics; and assess safety of macimorelin. The phase 1 thorough QT/QTc study, designed according to the International Council for Harmonisation E14 guideline, was a randomized, placebo-controlled, double-blind, 3-way complete crossover study comparing the effect of macimorelin 2.0 mg/kg with placebo and moxifloxacin 400 mg (positive control). Data were collected over a 3-month span from male (n=36) and female participants (n=24) aged 18 to 55 years with body mass index between 18.5 and 30.0 kg/m 2 . Fifty-six participants received all 3 treatments. The ΔΔQTcF for macimorelin showed a prolongation with a maximum mean value of 9.61 milliseconds (2-sided 90% confidence interval, 7.81 milliseconds and 11.41 milliseconds) at 4 hours after dosing. The 2-sided 90% confidence interval of this value also exceeded the 10 millisecond threshold at 3 hours after dosing. Assay sensitivity was confirmed with moxifloxacin. Other electrocardiogram parameters evaluated were not influenced by macimorelin. Macimorelin did not raise other safety concerns and was well tolerated. In summary, a single supratherapeutic dose of macimorelin prolonged cardiac repolarization according to the regulatory guideline., (© 2020 GlaxoSmithKline. Clinical Pharmacology in Drug Development published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Objective: The macimorelin test is approved for the diagnosis of adult growth hormone deficiency (AGHD) based on its efficacy vs the insulin tolerance test (ITT). Macimorelin has a significant advantage over ITT in avoiding hypoglycemia. Analyses were conducted to determine whether macimorelin performance is affected by age, BMI, or sex, and evaluate its performance vs ITT over a range of GH cutpoints., Design: Post hoc analyses of data from a previous randomized phase 3 study included participants aged 18-66 years with BMI <37 kg/m2 and high (Group A), intermediate (Group B), or low (Group C) likelihood for AGHD based on pituitary history, and matched controls (Group D)., Methods: Probability of AGHD was estimated using unadjusted, age-adjusted, BMI-adjusted, and sex-adjusted logistic models. Area under the curve (AUC) of the estimated receiver operating characteristic (ROC) curve (range, 0-1; 1 = perfect) was compared for adjusted vs unadjusted models. Separate analyses evaluated agreement, sensitivity, and specificity for macimorelin and ITT using cutpoints of 2.8, 4.0, 5.1, and 6.5 ng/mL., Results: For participants in Group A (n = 41) and Group D (n = 29), unadjusted, age-adjusted, BMI-adjusted, and sex-adjusted models had ROC AUCs (95% CIs) of 0.9924 (0.9807-1), 0.9924 (0.9807-1), 0.9916 (0.9786-1), and 0.9950 (0.9861-1), respectively., Conclusions: Macimorelin performance was not meaningfully affected by age, BMI, or sex, indicating robustness for AGHD diagnosis. Of the 4 GH cutpoints evaluated, the cutpoint of 5.1 ng/mL provided maximal specificity (96%) and high sensitivity (92%) and was in good overall agreement with the ITT at the same cutpoint (87%).

Background/aims: Diagnosis of growth hormone deficiency (GHD) in children requires the use of provocative growth hormone (GH) stimulation tests, which can have limited reliability and are potentially contraindicated in some patients. This is the first paediatric study to test the safety, tolerability, and pharmacokinetics (PK)/pharmacodynamics (PD) of macimorelin, an oral GH secretagogue, approved for diagnosis of adult GHD., Methods: In this open-label, group comparison, single-dose escalation trial (EudraCT 2018-001988-23), sequential cohorts of patients (C1-C3) received ascending single doses of macimorelin: 0.25 (C1), 0.5 (C2), and 1.0 (C3) mg/kg. Primary endpoints were safety and tolerability, and secondary endpoints were PK/PD., Results: Twenty-four patients aged between 2 and <18 with suspected GHD participated in the study. No macimorelin-related adverse events were reported, and macimorelin was well tolerated. Plasma macimorelin concentrations increased with dose: mean areas under the curve were 6.69 (C1), 18.02 (C2), and 30.92 (C3) h × ng/mL; mean maximum concentrations were 3.46 (C1), 8.13 (C2), and 12.87 (C3) ng/mL. GH concentration increased following macimorelin administration: mean times of maximum measured concentration were 52.5 (C1), 37.5 (C2), and 37.5 (C3) min., Conclusion: All 3 doses of macimorelin had excellent safety and tolerability with PK/PD profiles in expected ranges. These results support the use of 1.0 mg/mL macimorelin in a Phase 3 test validation trial in children., (© 2021 The Author(s) Published by S. Karger AG, Basel.)

Objective: Macimorelin is an orally active ghrelin receptor agonist indicated for the diagnosis of adult growth hormone (GH) deficiency in the United States. This phase 1 study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of single ascending doses of macimorelin (including a supratherapeutic dose to be used in a thorough QT trial) in healthy adults., Design: Participants were randomized to receive macimorelin 0.5, 1.0, or 2.0 mg/kg or placebo in 1 of 3 sequential ascending-dose cohorts. Blood samples for pharmacokinetic and pharmacodynamic assays were collected pre-dose and at specified time points over a 24-h period. Pharmacokinetic parameters assessed included area under the concentration-time curve (AUC), maximum concentration (C max ) of macimorelin in plasma, time to C max (t max ), and terminal elimination half-life (t 1/2 ). Pharmacodynamic assessments evaluated levels of GH, adrenocorticotropic hormone, thyroid-stimulating hormone, cortisol, and prolactin. Safety was assessed based on treatment-emergent adverse events (TEAEs), vital signs, 12‑lead electrocardiograms, and laboratory parameters., Results: A total of 28 healthy adults were enrolled and completed the study. Macimorelin AUC and C max showed less than dose-proportional increases following administration of 0.5 and 1.0 mg/kg. Mean t 1/2 was 3.51 h for macimorelin 0.5 and 1.0 mg/kg and 8.29 h for macimorelin 2.0 mg/kg; median t max occurred at 0.5 to 0.75 h. GH levels increased after dosing, with a t max of 0.75 h to 1.0 h. Mean GH C max was similar with the macimorelin 0.5- and 1.0-mg/kg doses (31.9 and 37.8 ng/mL, respectively) and was ~50% lower with macimorelin 2.0 mg/kg (18.4 ng/mL). Transient increases were observed in adrenocorticotropic hormone, cortisol, and prolactin, which were not dose related. A total of 19 TEAEs were reported in 35.7% (10/28) of participants; all TEAEs were mild or moderate and resolved. A total of 12 drug-related TEAEs were reported in 8 participants. Headache was the most common drug-related TEAE. All doses of macimorelin prolonged mean QTcF by 10 to 11 ms. There were no clinically meaningful changes in vital signs or laboratory parameters., Conclusions: Single-dose administration of macimorelin 0.5 to 2.0 mg/kg was well tolerated. Macimorelin exposure was less than dose-proportional over the dose range studied. Administration of macimorelin stimulated GH production, with the greatest increases observed in the macimorelin 0.5- and 1.0-mg/kg groups., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: RS and NA are employees of Aeterna Zentaris GmbH, and NK and VO are employees of Novo Nordisk, Inc., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: The diagnosis of adult GH deficiency (AGHD) is challenging and often requires confirmation with a GH stimulation test (GHST). The insulin tolerance test (ITT) is considered the reference standard GHST but is labor intensive, can cause severe hypoglycemia, and is contraindicated for certain patients. Macimorelin, an orally active GH secretagogue, could be used to diagnose AGHD by measuring stimulated GH levels after an oral dose., Materials and Methods: The present multicenter, open-label, randomized, two-way crossover trial was designed to validate the efficacy and safety of single-dose oral macimorelin for AGHD diagnosis compared with the ITT. Subjects with high (n = 38), intermediate (n = 37), and low (n = 39) likelihood for AGHD and healthy, matched controls (n = 25) were included in the efficacy analysis., Results: After the first test, 99% of macimorelin tests and 82% of ITTs were evaluable. Using GH cutoff levels of 2.8 ng/mL for macimorelin and 5.1 ng/mL for ITTs, the negative agreement was 95.38% (95% CI, 87% to 99%), the positive agreement was 74.32% (95% CI, 63% to 84%), sensitivity was 87%, and specificity was 96%. On retesting, the reproducibility was 97% for macimorelin (n = 33). In post hoc analyses, a GH cutoff of 5.1 ng/mL for both tests resulted in 94% (95% CI, 85% to 98%) negative agreement, 82% (95% CI, 72% to 90%) positive agreement, 92% sensitivity, and 96% specificity. No serious adverse events were reported for macimorelin., Conclusions: Oral macimorelin is a simple, well-tolerated, reproducible, and safe diagnostic test for AGHD with accuracy comparable to that of the ITT. A GH cutoff of 5.1 ng/mL for the macimorelin test provides an excellent balance between sensitivity and specificity.

Purpose: Zoptarelin doxorubicin is a fusion molecule of the chemotherapeutic doxorubicin and a luteinizing hormone-releasing hormone receptor (LHRHR) agonist, designed for drug targeting to LHRHR positive tumors. The aim of this study was to establish a physiologically based pharmacokinetic (PBPK) parent-metabolite model of zoptarelin doxorubicin and to apply it for drug-drug interaction (DDI) potential analysis., Methods: The PBPK model was built in a two-step procedure. First, a model for doxorubicin was developed, using clinical data of a doxorubicin study arm. Second, a parent-metabolite model for zoptarelin doxorubicin was built, using clinical data of three different zoptarelin doxorubicin studies with a dosing range of 10-267 mg/m 2 , integrating the established doxorubicin model. DDI parameters determined in vitro were implemented to predict the impact of zoptarelin doxorubicin on possible victim drugs., Results: In vitro, zoptarelin doxorubicin inhibits the drug transporters organic anion-transporting polypeptide 1B3 (OATP1B3) and organic cation transporter 2 (OCT2). The model was applied to evaluate the in vivo inhibition of these transporters in a generic manner, predicting worst-case scenario decreases of 0.5% for OATP1B3 and of 2.5% for OCT2 transport rates. Specific DDI simulations using PBPK models of simvastatin (OATP1B3 substrate) and metformin (OCT2 substrate) predict no significant changes of the plasma concentrations of these two victim drugs during co-administration., Conclusions: The first whole-body PBPK model of zoptarelin doxorubicin and its active metabolite doxorubicin has been successfully established. Zoptarelin doxorubicin shows no potential for DDIs via OATP1B3 and OCT2.

Background: There is increasing evidence of a constitutive activation of Akt in pancreatic ductal adenocarcinoma (PDAC), associated with poor prognosis and chemoresistance. Therefore, we evaluated the expression of phospho-Akt in PDAC tissues and cells, and investigated molecular mechanisms influencing the therapeutic potential of Akt inhibition in combination with gemcitabine., Methods: Phospho-Akt expression was evaluated by immunohistochemistry in tissue microarrays (TMAs) with specimens tissue from radically-resected patients (n = 100). Data were analyzed by Fisher and log-rank test. In vitro studies were performed in 14 PDAC cells, including seven primary cultures, characterized for their Akt1 mRNA and phospho-Akt/Akt levels by quantitative-RT-PCR and immunocytochemistry. Growth inhibitory effects of Akt inhibitors and gemcitabine were evaluated by SRB assay, whereas modulation of Akt and phospho-Akt was investigated by Western blotting and ELISA. Cell cycle perturbation, apoptosis-induction, and anti-migratory behaviors were studied by flow cytometry, AnnexinV, membrane potential, and migration assay, while pharmacological interaction with gemcitabine was determined with combination index (CI) method., Results: Immunohistochemistry of TMAs revealed a correlation between phospho-Akt expression and worse outcome, particularly in patients with the highest phospho-Akt levels, who had significantly shorter overall and progression-free-survival. Similar expression levels were detected in LPC028 primary cells, while LPC006 were characterized by low phospho-Akt. Remarkably, Akt inhibitors reduced cancer cell growth in monolayers and spheroids and synergistically enhanced the antiproliferative activity of gemcitabine in LPC028, while this combination was antagonistic in LPC006 cells. The synergistic effect was paralleled by a reduced expression of ribonucleotide reductase, potentially facilitating gemcitabine cytotoxicity. Inhibition of Akt decreased cell migration and invasion, which was additionally reduced by the combination with gemcitabine. This combination significantly increased apoptosis, associated with induction of caspase-3/6/8/9, PARP and BAD, and inhibition of Bcl-2 and NF-kB in LPC028, but not in LPC006 cells. However, targeting the key glucose transporter Glut1 resulted in similar apoptosis induction in LPC006 cells., Conclusions: These data support the analysis of phospho-Akt expression as both a prognostic and a predictive biomarker, for the rational development of new combination therapies targeting the Akt pathway in PDAC. Finally, inhibition of Glut1 might overcome resistance to these therapies and warrants further studies.

Introducing a second chiral center on our previously described 1,2,4-triazole, allowed us to increase diversity and elongate the 'C-terminal part' of the molecule. Therefore, we were able to explore mimics of the substance P analogs described as inverse agonists. Some compounds presented affinities in the nanomolar range and potent biological activities, while one exhibited a partial inverse agonist behavior similar to a Substance P analog., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Ghrelin receptor ligands based on a trisubstituted 1,2,4-triazole scaffold were recently synthesized and evaluated for their in vitro affinity for the GHS-R1a receptor and their biological activity. In this study, replacement of the α-aminoisobutyryl (Aib) moiety (a common feature present in numerous growth hormone secretagogues described in the literature) by aromatic and heteroaromatic groups was explored. We found potent antagonists incorporating the picolinic moiety in place of the Aib moiety. In an attempt to increase affinity and activity of our lead compound 2, we explored the modulation of the pyridine ring. Herein we report the design and the structure-activity relationships study of these new ghrelin receptor ligands., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A novel series of (7-aryl-1,5-naphthyridin-2-yl)ureas was discovered as dual ERK2 and Aurora B kinases inhibitors. Several analogues were active at micromolar and submicromolar range against ERK2 and Aurora B, associated with very promising antiproliferative activity toward various cancer cell lines. Synthesis, structure activity relationship and docking study are reported. In vitro ADME properties and safety data are also discussed., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Objectives: To evaluate the activity and toxicity of AEZS-108 (Zoptarelin Doxorubicin Acetate) an LHRH agonist linked to doxorubicin in women with platinum refractory or resistant ovarian cancer expressing LHRH receptors., Methods: Women with epithelial ovarian, fallopian tube or primary peritoneal cancer, expressing LHRH receptors were eligible for this trial, when they had progression during treatment with a platinum based regimen or within 6months after receiving a platinum based regimen and a previous taxane treatment. At least one measurable target lesion (RECIST) or CA-125 levels higher than twice the upper limit of normal range (GCIG-criteria) were required. Patients received AEZS-108 (267mg/m(2) equimolar to 76.8mg/m(2) of free doxorubicin) every 3weeks as a two hour i.v. infusion., Results: Fifty-five of 59 (93%) of ovarian cancer samples screened expressed LHRH receptors. 42 patients were enrolled in this study and received at least 1 infusion of AEZS-108 (ITT population). Of these 42 patients 6 (14.3%) had a partial response, 16 (38%) stable disease, 16 (38%) progressive disease and 4 patients were not evaluable. Median time to progression was 12weeks (95% CI: 8-20weeks), and median overall survival was 53weeks (95% CI: 39-73weeks). Toxicity profile was favorable., Conclusion: AEZS-108 has a clinical activity in platinum refractory/resistant ovarian cancer which seems to be comparable to that of pegylated liposomal doxorubicin or to topotecan. Toxicity was comparably low. These data support the concept of a targeted chemotherapy for tumors expressing LHRH receptors., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: Advanced or recurrent endometrial cancer (EC) no longer amenable to surgery or radiotherapy is a life-threatening disease with limited therapeutic options left. Eighty percent of ECs express receptors for luteinizing hormone-releasing hormone (LHRH), which can be targeted by AEZS-108 (zoptarelin doxorubicin acetate). This phase 2 trial was performed to assess the efficacy and safety of AEZS-108 in this group of patients., Methods: Patients had FIGO (Fédération Internationale de Gynécologie et d'Obstétrique) III or IV or recurrent EC, LHRH receptor-positive tumor status, and at least had 1 measurable lesion (Response Evaluation Criteria in Solid Tumors). Prior anthracycline therapy was not allowed. Patients received AEZS-108 as a 2-hour infusion on day 1 of a 21-day cycle. The treatment was continued for a maximum of 6 to 8 cycles. The primary end point was the response rate determined by the Response Evaluation Criteria in Solid Tumors., Results: From April 2008 to November 2009, 44 patients were included in the study at 8 centers in Germany (AGO) and 3 centers in Bulgaria. Forty-three of these patients were eligible. Two (5%) patients had a complete remission, and 8 (18%) achieved a partial remission. Stable disease for at least 6 weeks was observed in 44%. The median time to progression was 7 months, and the median overall survival was 15 months. The most frequently reported grade 3 or 4 adverse effects were neutropenia (12%) and leucopenia (9%)., Conclusions: AEZS-108, an LHRH-agonist coupled to doxorubicin, has significant activity and low toxicity in women with advanced or recurrent LHRH receptor-positive EC, supporting the principle of receptor-mediated targeted chemotherapy.

Miltefosine was originally formulated and registered as a topical treatment for cutaneous cancers. For this indication and in subsequent development for leishmaniasis, a large body of non-clinical data has been generated. The gastrointestinal organ is the main site of toxicity, in both animal and in human studies. The testis and retina were identified as target organs in rats, although corresponding changes were not observed in clinical studies in humans. In terms of pharmacokinetics, the terminal elimination half-life is long (84h and 159h in rats and dogs respectively). Miltefosine is widely distributed in body organs and not metabolized by cytochrome P450 enzymes in vitro. The drug is embryotoxic and fetotoxic in rats and rabbits, and teratogenic in rats but not in rabbits. It is therefore contraindicated for use during pregnancy, and contraception is required beyond the end of treatment in women of child-bearing age.

1-Phenyl-4-piperazinyl-carbonyl-substituted nitrogen-containing heterocycles were discovered at Zentaris as a new class of potent, synthetic, small molecule tubulin inhibitors with strong antiproliferative activity. The lead structure of this class, D-24203, proved to be a potent inhibitor of in vivo tumor growth in different xenograft models including mammary and renal cancers. As part of our efforts in the lead optimization process to expand structural diversity as well as to optimize bioavailability parameters such as solubility and metabolic stability for these compounds, we produced and evaluated a focused library containing 320 compounds. Five new heterocyclic compound classes with comparable activity properties in the cytotoxicity and tubulin polymerization assay could be identified. In silico calculated bioavailability parameters for selected library members provides new compound classes with improved solubility properties. Library design, development of adequate solution phase methodology, and synthesis will be presented, as well as results of lead optimization.

Oral miltefosine was administered to 39 human immunodeficiency virus (HIV)-infected patients with leishmaniasis for whom standard leishmaniasis treatment had failed. Initial response was achieved in 25 patients (64%), including 16 patients (43%) with initial parasitological cure. Repeated responses after relapse and tolerability of long courses of treatment indicate the potential for development of optimized dosage schemes.