Combination of Abiraterone Acetate, Prostate Bed Radiotherapy, and Luteinizing Hormone-releasing Hormone Agonists in Biochemically Relapsing Patients After Prostatectomy (CARLHA): A Phase 2 Clinical Trial.

BACKGROUND: The relevance of next-generation hormone therapies and circulating tumor cells (CTCs) are not elucidated in biochemical recurrence after prostatectomy. OBJECTIVE: To evaluate the combination of abiraterone acetate plus prednisone (AAP), prostate bed radiotherapy (PBRT), and goserelin in biochemically relapsing men after prostatectomy, and to investigate the utility of CTCs. DESIGN, SETTING, AND PARTICIPANTS: In this single-arm multicenter phase 2 trial, 46 biochemically relapsing men were enrolled between December 2012 and January 2019. The median follow-up was 47 mo. INTERVENTION: All patients received AAP 1000 mg daily (but 750 mg during PBRT), salvage PBRT, and goserelin. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was 3-yr biochemical recurrence-free survival (bRFS) when prostate-specific antigen (PSA) levels were ≥0.2 ng/ml. The secondary outcomes included alternative bRFS (alt-bRFS) when PSA levels were ≥0.5 ng/ml and safety assessment. CTC count was assessed. RESULTS AND LIMITATIONS: The 3-yr bRFS and alt-bRFS were 81.5% (95% confidence interval or CI [66.4-90.3%]) and 95.6% (95% CI [83.5-98.9%]), respectively. The most common acute radiotherapy-related adverse effect (AE; all grades was pollakiuria (41.3%). The most common late AE (all grades) was urinary incontinence (15.2%). Grade 3-4 acute or late radiotherapy-related AEs were scarce. Most frequent AEs nonrelated to radiotherapy were hot flashes (76%), hypertension (63%), and hepatic cytolysis (50%, of which 20% were of grades 3-4). Of the patients, 11% had a CTC count of ≥5, which was correlated with poorer bRFS (p = 0.042) and alt-bRFS (p = 0.008). The association between CTC count and higher rates of relapse was independent of the baseline PSA level and PSA doubling time (p = 0.42 and p = 0.09, respectively). This study was nonrandomized with a limited number of patients, and few clinical events were reported. CONCLUSIONS: Adding AAP to salvage radiation therapy and goserelin resulted in high bRFS and alt-bRFS. AEs remained manageable, although a close liver surveillance is advised. CTC count appears as a promising biomarker for prognosis and predicting response to treatment. PATIENT SUMMARY: Our study was a phase 2 clinical trial that exhibited the efficacy and tolerance of a novel androgen-receptor targeting agent (abiraterone acetate plus prednisone) in patients with prostate cancer who experienced rising prostate-specific antigen after radical prostatectomy, in combination with prostate bed radiotherapy. The results also indicated the feasibility and potential value of circulating tumor cell detection, which constitutes a possible advance in managing prostate cancers.

Discovery of the Clinical Candidate IDOR-1117-2520: A Potent and Selective Antagonist of CCR6 for Autoimmune Diseases.

Migration of immune cells to sites of inflammation is a critical step in the body's response to infections but also during autoimmune flares. Chemokine receptors, members of the GPCR receptors, are instrumental in directing specific cell types to their target organs. Herein, we describe a highly potent small molecule antagonist of the chemokine receptor CCR6, which came out of fine-tuned structural elaborations from a proprietary HTS hit. Three main issues in the parent chemical series-cytotoxicity, phototoxicity, and hERG, were successfully solved. Biological characterization demonstrated that compound 45 (IDOR-1117-2520) is a selective and insurmountable antagonist of CCR6. In vivo proof-of-mechanism studies in a mouse lung inflammation model using a representative compound from the chemical class of 45 confirmed that the targeted CCR6+ cells were efficiently inhibited from migrating into the bronchoalveoli. Finally, ADMET and physicochemical properties were well balanced and the preclinical package warranted progress in the clinic.

Stereotactic body radiotherapy as a viable treatment on extracranial oligometastases in melanoma patients: a retrospective multicentric study.

Introduction: Stereotactic radiotherapy (SBRT) potentially has a role in the management of oligometastatic melanoma. However, literature with data specific to this management is very limited. The objectives of this study were to evaluate the time to local control (LC) of extra-cranial melanoma metastases after SBRT treatment and to help establish if SBRT is a useful therapy for oligometastatic melanoma. Methods: A retrospective study was conducted with data collected from two referral centers in France between 2007 and 2020. The oligometastatic status of patients was reported based on the latest recommendations with a maximum of three lesions prior to treatment. Results: A total of 69 patients receiving SBRT for 88 oligometastatic melanoma metastases were included. The median follow-up time was 42.6 months. Most patients were treated for metachronous oligometastatic lesions. Occurrence of oligoprogression, oligorecurrence, and oligopersistence was reported in 42.0%, 39.1%, and 17.4% of cases, respectively. Treated lesions were mostly pulmonary (40.6%), followed by lymph node (34.8%) and hepatic sites (24.6%). Progression-free survival at 1, 2, and 3 years were 47.0% (35-59), 27.0% (16-39), and 25.0% (15.0-37.0), respectively. Time to LC rates at 1, 2, and 3 years were 94.2% (87.0-98.1), 90.3% (81.3-96.1), and 90.3% (81.3-96.1), respectively. Overall survival at 1, 2, and 3 years were 87% (76.0-93.0), 74.0% (76.0-93.0), and 61.0% (47.0-73.0), respectively. Only 17.4% of patients experienced acute, grade 1 or grade 2 toxicities with no reports of grade 3 or higher toxicities. Conclusion: SBRT demonstrated efficacy in managing melanoma patients with extracranial oligometastases and showed an overall low toxicity profile. Future randomized studies are needed to establish the role of SBRT in therapeutic approaches for patients with oligometastatic melanoma.

Prostatectomy Bed Image-guided Dose-escalated Salvage Radiotherapy (SPIDER): An International Multicenter Retrospective Study.

BACKGROUND: Management of macroscopic local recurrence (MLR) after radical prostatectomy is a challenging situation with no standardized approach. OBJECTIVE: The objective of our study was to assess the efficacy and safety of functional image-guided salvage radiotherapy (SRT) in patients with MLR in the prostate bed. DESIGN, SETTING, AND PARTICIPANTS: In this international multicenter retrospective study across 16 European centers, eligible patients were initially treated by radical prostatectomy (RP) with or without pelvic lymph node dissection for localized or locally advanced adenocarcinoma of the prostate. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Prostate-specific antigen (PSA) measured 4 wk after RP was <0.1 ng/ml. All patients presented a biochemical relapse after RP defined by an increase in PSA level of ≥0.2 ng/ml on two successive measures. Only patients with an MLR lesion in the prostatectomy bed visualized on functional imaging (multiparametric magnetic resonance imaging, positron emission tomography/computed tomography [PET/CT] choline, or PET/CT prostate-specific membrane antigen) were eligible. Patients with lymph node, bone, or visceral dissemination at restaging imaging (CT and/or bone scintigraphy and/or magnetic resonance imaging and/or PET) were excluded. Dose escalation was defined as a dose of >66 Gy prescribed to the prostate bed or to MLR. Toxicities were classified using the Common Terminology Criteria for Adverse Events scale, version 4.03. The primary endpoint was progression-free survival (PFS). Secondary outcomes were metastasis-free survival (MPFS), biochemical progression-free survival, and overall survival. Genitourinary (GU) and gastrointestinal (GI) toxicities were analyzed. RESULTS AND LIMITATIONS: Between January 2000 and December 2019, 310 patients received at least one dose escalation on MLR and 25 patients did not receive any dose escalation. The median PSA level before SRT was 0.63 ng/ml (interquartile range [IQR], 0.27-1.7). The median follow-up was 54 mo (IQR, 50-56). Five-year PFS and MPFS were 70% (95% confidence interval [CI]: [64; 75]) and 84% (95% CI: [78; 88]), respectively. Grade ≥2 GU and GI late toxicities were observed in 43 (12%) and 11 (3%) patients, respectively. When the prescribed dose on the MLR lesion was ≥72 Gy, an improvement in 5-yr PFS was found for patients received at least one dose escalation (73% [95% CI: 65-79]) vs 60% [95% CI: 48; 70]; p = 0.03). CONCLUSIONS: In this contemporary study integrating functional imaging data, we found potential efficacy of SRT with dose escalation ≥72 Gy for patients with MLR in the prostate bed and with an acceptable toxicity profile. Prospective data exploring this MLR dose escalation strategy are awaited. PATIENT SUMMARY: In this report, we looked at the outcomes from salvage radiotherapy for prostate cancer and macroscopic relapse in a large European population. We found that outcomes varied with prostate-specific antigen at relapse, Gleason score, and dose escalation. We found potential efficacy of salvage radiotherapy with dose escalation for macroscopic relapse in the prostate bed, with an acceptable toxicity profile.

Randomized phase II trial in prostate cancer with hormone-sensitive OligometaSTatic relapse: Combining stereotactic ablative radiotherapy and durvalumab (POSTCARD GETUG P13): Study protocol.

Background: As in other solid tumors, increasing evidence indicates that patients diagnosed with a limited number of prostate cancer metastases, so-called oligometastases, have a better prognosis than patients with extensive metastatic disease. Stereotactic body radiotherapy (SBRT) is now considered an option in this population.Programmed death-1 (PD-1) and its ligands (PD-L1) are targeted by immune checkpoint inhibitors. Preclinical studies have shown that the tumor immune microenvironment changes when combining radiotherapy with immunotherapy, especially with hypofractionated radiotherapy.The oligometastatic setting appears to be the most relevant clinical situation for evaluating the immune response generated by radiotherapy and immune checkpoint inhibitors in patients with an intact immune system.We hypothesize that durvalumab will enhance the immune response following SBRT targeting oligometastatic lesions. Our purpose is to demonstrate, via a randomized 2:1 phase II trial, that SBRT (3 fractions) with durvalumab in oligometastatic hormone-sensitive prostate cancer patients would improve progression-free survival in patients with prostate cancer with up to 5 metastases compared to patients who exclusively received SBRT. Methods: This is a multicentric randomized phase II study in French academic hospitals. Patients with prostate cancer and up to 5 metastases (lymph node and/or bone) were randomized into a 2:1 ratio between Arm A (experimental group), corresponding to durvalumab and SBRT to the metastases, and Arm B (control group), corresponding to SBRT alone to the metastases. The study aims to accrue a total of 96 patients within 3 years. The primary endpoint is two-year progression-free survival and secondary endpoints include androgen deprivation therapy-free survival, quality of life, toxicity, prostate cancer specific survival, overall survival, and immune response. Discussion: The expected benefit for the patients in the experimental arm is longer life expectancy with acceptable toxicity. We also expect our study to provide data for better understanding the synergy between immunotherapy and radiotherapy in oligometastatic prostate cancer.

Discovery of Clinical Candidate ACT-777991, a Potent CXCR3 Antagonist for Antigen-Driven and Inflammatory Pathologies.

The CXCR3 chemokine receptor is a G protein-coupled receptor mainly expressed on immune cells from the lymphoid lineage, including activated T cells. Binding of its inducible chemokine ligands CXCL9, CXCL10, and CXCL11 leads to downstream signaling events and the migration of activated T cells to sites of inflammation. Herein, we report the third part of our CXCR3 antagonist program in the field of autoimmunity, culminating in the discovery of the clinical compound ACT-777991 (8a). A previously disclosed advanced molecule was exclusively metabolized by the CYP2D6 enzyme, and options to address the issue are described. ACT-777991 is a highly potent, insurmountable, and selective CXCR3 antagonist that showed dose-dependent efficacy and target engagement in a mouse model of acute lung inflammation. The excellent properties and safety profile warranted progress in the clinics.

The Safety and Efficacy of Salvage Stereotactic Radiation Therapy in Patients with Intraprostatic Tumor Recurrence After Previous External Radiation Therapy: Phase 1 Results from the GETUG-AFU 31 Study.

BACKGROUND: There is no consensus on the best local salvage treatment for prostate cancer recurrence after primary external beam radiotherapy. Prospective data on stereotactic body radiation therapy (SBRT) are very scarce. OBJECTIVE: To determine the optimal dose regimen for salvage SBRT. DESIGN, SETTING, AND PARTICIPANTS: The present report concerns the phase 1 part of the GETUG-AFU 31 multicenter open-label study. The main inclusion criteria were histologically proven biochemical recurrence, clinical stage T1-T2 upon relapse, multiparametric magnetic resonance imaging data, prostate-specific antigen (PSA) level ≤10 ng/ml prior to salvage SBRT, PSA doubling time >10 mo, and an International Prostate Symptom Score of ≤12. INTERVENTION: Five or six fractions of 6 Gy were delivered using focal SBRT. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Dose-limiting toxicity (DLT) was defined as grade ≥3 gastrointestinal or genitourinary tract toxicity, or any grade 4 toxicity (according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03) occurring in the first 18 wk following treatment initiation. A time-to-event continual reassessment method was used to select the dose regimen. RESULTS AND LIMITATIONS: Twenty-one patients were treated (median [interquartile range] age: 76.8 yr [72.2-80.8]), including 12 at 6 × 6 dose level. No DLT was observed. The acute grade 2 genitourinary tract toxicity rate was 19%. With a median follow-up of 12.3 mo, the estimated cumulative incidence of late grade 2 genitourinary toxicity was 41.2% (95% confidence interval: 18.1-63.1%). No grade >2 genitourinary toxicity and no grade ≥2 gastrointestinal toxicity were reported. All treated patients were alive and relapse free at the last follow-up. CONCLUSIONS: A 6 × 6 Gy dose regimen was selected for our phase 2 study of salvage SBRT. With a short follow-up period, the level of toxicity appears to be acceptable. PATIENT SUMMARY: There is no consensus on the best local treatment for patients with local relapse after radiotherapy for prostate cancer. Prospective data are very scarce. Our early phase trial allowed us to recommend six fractions of 6 Gy using high-precision radiotherapy for further studies.

Real-Life Study of the Benefit of Concomitant Radiotherapy with Cemiplimab in Advanced Cutaneous Squamous Cell Carcinoma (cSCC): A Retrospective Cohort Study.

BACKGROUND: Cemiplimab is a monoclonal antibody targeting the PD-1, and phase II trials have shown its efficacy in the treatment of advanced cutaneous squamous cell carcinoma in patients who are not candidates for curative surgery or radiation therapy as a first- or later-line treatment. A synergistic antitumoral response has been demonstrated with concurrent radiotherapy and PD1-immunotherapy. However, no real-life study has demonstrated this effect in advanced cutaneous squamous cell carcinoma. METHODS: We conducted a real-life retrospective cohort study to investigate the benefit of concomitant therapy in 33 patients treated with cemiplimab at the University Hospital of Caen, alone (C group) or concomitant to radiotherapy (C/RT group). Our primary objectives were to evaluate the best overall response and objective response rate. Our secondary objectives were the disease control rate, median time to response, progression-free survival, overall survival, clinical benefit of radiotherapy, and safety data. After stopping cemiplimab administration, we performed a follow-up of our patients and performed a descriptive study. RESULTS: We reported an objective response rate of 45.5%, including 47.6% in the cemiplimab group versus 41.6% in the concomitant group. The addition of radiotherapy to cemiplimab enables an earlier clinico-radiological response, with a median duration of 5.5 months in the cemiplimab group versus 3 months in the concomitant therapy group. The response to treatment was prolonged despite discontinuation of cemiplimab, with 91.6% (n = 11/12) and 83.3% (n = 10/12) patients in complete or partial remission at 6 months and 1 year after cessation of cemiplimab and no switch to another oncological treatment, respectively. Radiation therapy also provided a therapeutic effect in 83.3% of the patients in the concomitant group, without increasing the occurrence of adverse events. CONCLUSIONS: Our study confirms the efficacy of cemiplimab and radiotherapy in the management of advanced cutaneous squamous cell carcinoma. Concomitant therapy permitted to obtain an earlier radiological response, a beneficial local therapeutic effect of radiotherapy, without any safety alert.

Design, Synthesis, and Pharmacological Evaluation of Benzimidazolo-thiazoles as Potent CXCR3 Antagonists with Therapeutic Potential in Autoimmune Diseases: Discovery of ACT-672125.

The chemokine receptor CXCR3 allows the selective recruitment of innate and adaptive inflammatory immune cells into inflamed tissue. CXCR3 ligands are secreted after exposure to pro-inflammatory cytokines. Upon binding to CXCR3 ligands, CXCR3 expressing T-lymphocytes migrate toward sites of inflammation and can promote tissue damage. Therefore, antagonizing this receptor may provide clinical benefits for patients suffering from autoimmune diseases characterized by high concentrations of CXCR3 ligands. Herein, we report the second part of our CXCR3 discovery program where we explored the benzimidazolo-thiazole core scaffold. The optimization of potency and the mitigation of an hERG liability are described. Further pharmacokinetic considerations led to the identification of the potent CXCR3 antagonist ACT-672125 (29). The compound showed good physicochemical properties and safety profile. In a proof-of-mechanism model of lung inflammation, ACT-672125 inhibited the recruitment of CXCR3 expressing T cells into the inflamed lung in a dose-dependent manner.

Discovery and In Vivo Evaluation of ACT-660602: A Potent and Selective Antagonist of the Chemokine Receptor CXCR3 for Autoimmune Diseases.

The chemokine receptor CXCR3 is a seven-transmembrane G-protein-coupled receptor (GPCR) involved in various pathologies, in particular autoimmune diseases. It is activated by the three chemokine ligands CXCL9, CXCL10, and CXCL11 and enables the recruitment of immune cell subsets leading to damage of inflamed tissues. Starting from a high-throughput screening hit, we describe the iterative optimization of a chemical series culminating in the discovery of the selective CXCR3 antagonist ACT-660602 (9j). The careful structural modifications during the lead optimization phase led to a compound with high biological potency in inhibiting cell migration together with improvements of the metabolic stability and hERG issue. In a LPS-induced lung inflammation model in mice, ACT-660602 led to significantly reduced recruitment of the CXCR3+ CD8+ T cell in the bronchoalveolar lavage compartment when administered orally at a dose of 30 mg/kg.

Implantation of tissue expander prior to irradiation in the era of intensity modulated radiotherapy: impact on the management of patients with pelvic digestive cancers.

PURPOSE: Before the introduction of intensity-modulated radiation therapy (IMRT), few teams used to implant a pelvic tissue expander to keep the bowel away from the radiation field, so as to reduce the risk of acute and late enteritis. However, this unexpected surgery could impact patient's overall treatment and may be no more necessary in the era of modern radiotherapy. MATERIAL AND METHODS: This is a retrospective cross-sectional study including 13 patients who underwent tissue expander implantation before radiotherapy or chemoradiotherapy for rectal or anal carcinoma between November 2008 and March 2019. First, we aim to show that IMRT could sometimes be insufficient to respect dosimetric constraints, and then we aim to report the impact of tissue expander implantation on the global strategy of care of patients with anal and rectal cancers. RESULTS: Seventy-seven percent of the included patients were treated for anal neoplasms, while the remaining 23% had locally advanced rectal cancer. The median follow-up since implantation of the expander was 51 months [3.7-115]. Three patients recurred. One patient developed grade III toxicity related to the implantation of a tissue expander. The delay between diagnosis and the start of irradiation was significantly prolonged (median of 3 months), requiring unusual induction chemotherapy. CONCLUSION: Implantation of tissue expander prior to chemoradiotherapy should be considered, even in the era of IMRT, when irradiated peritoneal cavity volume (V15Gy-V45Gy) far exceeds usual dose constraints. However, it impacts the global strategy of care by delaying the start of irradiation, by introducing induction chemotherapy, and rarely by causing post-operative complications.

Salvage Stereotactic Body Radiation Therapy for Local Prostate Cancer Recurrence After Radiation Therapy: A Retrospective Multicenter Study of the GETUG.

PURPOSE: To assess the efficacy and safety of salvage stereotactic body radiation therapy (SBRT) in patients with biopsy-proven local prostate cancer recurrence after radiation therapy. METHODS AND MATERIALS: Between April 2010 and January 2017, 100 patients were included in 7 centers. Disease extension was assessed by pelvic multiparametric magnetic resonance imaging and choline positron emission tomography in 87% and 94% of patients, respectively. The median time interval between the 2 treatments was 7.5 years (range, 2-18). Median prostate-specific antigen at recurrence was 4.3 ng/mL (range, 2-38). Median SBRT dose was 36 Gy (range, 25-36.25) in 6 fractions (range, 5-6), every other day. Thirty-four percent of patients were treated by androgen deprivation therapy for a median duration of 12 months. Toxicity was assessed according to Common Terminology Criteria for Adverse Events version 4.03. RESULTS: Median follow-up was 29.3 months (range, 4-91). Second biochemical recurrence-free survival rate at 3 years was 55% (95% confidence interval [CI], 42%-66%). The initial D'Amico group, time interval after first radiation therapy, and SBRT dose were prognostic factors of biochemical recurrence-free survival in multivariate analysis (P = .09, P = .025, P = .018, respectively). No patient developed acute gastrointestinal toxicity of grade >1; rates of acute genitourinary toxicity of grade 2 and 3 were 8% and 1%, respectively. The actuarial 3-year grade ≥2 genitourinary and gastrointestinal toxicity was 20.8% (95% CI, 13%-29%) and 1% (95% CI, 0.1%-5.1%), respectively. One patient presented with neuritis of grade 3. CONCLUSIONS: With a short follow-up, this study shows that salvage SBRT allows for encouraging control and acceptable toxicity. Further prospective studies are necessary to confirm these preliminary results and to determine late toxicity.

Stereotactic radiation therapy in the strategy of treatment of metastatic renal cell carcinoma: A study of the Getug group.

BACKGROUND: Renal cell carcinoma (RCC) is usually considered radioresistant, but stereotactic radiation therapy (SRT) may increase local disease control. This study aimed to assess the benefit of SRT in the management of metastatic RCC patients. METHODS: Data of all RCC patients who received SRT between 2008 and 2015 with curative intent were retrospectively collected in six French referral centres. Local control (LC), progression-free survival (PFS), local recurrence-free survival (LRFS), time to systemic therapy (TTS) and overall survival (OS) were assessed. RESULTS: One hundred and eighty-eight patients treated with SRT for 252 RCC metastases (brain [n = 120]; spine [n = 75]; and others [n = 57]) were recensed. SRT was performed for oligoprogressive disease (101 patients), oligometastatic disease (80 patients) or residual tumour after a partial response to systemic treatment (7 patients). The median biologically effective dose was 78 Gy. For the whole population, local control rates at 6, 12 and 24 months were 87.5%, 82.9% and 77.6%, respectively; median PFS, LRFS, TTS and OS were 8.5, 23.2, 13.2 and 29.2 months, respectively. Among patients treated for oligoprogressive/oligometastatic disease, the median PFS, TTS, and OS were 8.6/7.6, 10.5/14.2 and 23.2/33.9 months, respectively. Among the 7 patients treated with SRT after partial response to systemic treatment, no relapse occurred for 3 of them after a median follow-up of 22 months. Acute and late severe toxicities were noted in 5 (2.6%) patients. CONCLUSIONS: SRT is effective and safe for oligometastatic and oligoprogressive RCC patients and may delay introduction or change of systemic therapy.

4-((R)-2-{[6-((S)-3-Methoxypyrrolidin-1-yl)-2-phenylpyrimidine-4-carbonyl]amino}-3-phosphonopropionyl)piperazine-1-carboxylic Acid Butyl Ester (ACT-246475) and Its Prodrug (ACT-281959), a Novel P2Y12 Receptor Antagonist with a Wider Therapeutic Window in the Rat Than Clopidogrel.

Recent post hoc analyses of several clinical trials with P2Y12 antagonists showed the need for new molecules being fully efficacious as antiplatelet agents and having a reduced propensity to cause major bleeding. We have previously reported the discovery of the 2-phenylpyrimidine-4-carboxamide analogs as P2Y12 antagonists with nanomolar potency in the disease-relevant platelet aggregation assay in human plasma. Herein we present the optimization steps that led to the discovery of clinical candidate ACT-246475 (30d). The key step was the replacement of the carboxylic acid functionality by a phosphonic acid group which delivered the most potent molecules of the program. In addition, low in vivo clearance in rat and dog was achieved for the first time. Since the bioavailability of 30d was low in rat and dog, we developed the bis((isopropoxycarbonyl)oxy)methyl ester prodrug (ACT-281959, 45). Compound 30d showed efficacy in the rat ferric chloride thrombosis model when administered intravenously as parent or orally as its prodrug 45. Moreover, 30d displays a wider therapeutic window as compared to clopidogrel in the rat surgical blood loss model.

Optimization of 2-phenyl-pyrimidine-4-carboxamides towards potent, orally bioavailable and selective P2Y(12) antagonists for inhibition of platelet aggregation.

2-Phenyl-pyrimidine-4-carboxamide analogs were identified as P2Y12 antagonists. Optimization of the carbon-linked or nitrogen-linked substituent at the 6-position of the pyrimidine ring provided compounds with excellent ex vivo potency in the platelet aggregation assay in human plasma. Compound 23u met the objectives for activity, selectivity and ADMET properties.

Crystal structures of tRNA-guanine transglycosylase (TGT) in complex with novel and potent inhibitors unravel pronounced induced-fit adaptations and suggest dimer formation upon substrate binding.

The bacterial tRNA-guanine transglycosylase (TGT) is a tRNA modifying enzyme catalyzing the exchange of guanine 34 by the modified base preQ1. The enzyme is involved in the infection pathway of Shigella, causing bacterial dysentery. As no crystal structure of the Shigella enzyme is available the homologous Zymomonas mobilis TGT was used for structure-based drug design resulting in new, potent, lin-benzoguanine-based inhibitors. Thorough kinetic studies show size-dependent inhibition of these compounds resulting in either a competitive or non-competitive blocking of the base exchange reaction in the low micromolar range. Four crystal structures of TGT-inhibitor complexes were determined with a resolution of 1.58-2.1 A. These structures give insight into the structural flexibility of TGT necessary to perform catalysis. In three of the structures molecular rearrangements are observed that match with conformational changes also noticed upon tRNA substrate binding. Several water molecules are involved in these rearrangement processes. Two of them demonstrate the structural and catalytic importance of water molecules during TGT base exchange reaction. In the fourth crystal structure the inhibitor unexpectedly interferes with protein contact formation and crystal packing. In all presently known TGT crystal structures the enzyme forms tightly associated homodimers internally related by crystallographic symmetry. Upon binding of the fourth inhibitor the dimer interface, however, becomes partially disordered. This result prompted further analyses to investigate the relevance of dimer formation for the functional protein. Consultation of the available TGT structures and sequences from different species revealed structural and functional conservation across the contacting residues. This suggests that bacterial and eukaryotic TGT could possibly act as homodimers in catalysis. It is hypothesized that one unit of the dimer performs the catalytic reaction whereas the second is required to recognize and properly orient the bound tRNA for the catalytic reaction.

Evolution of a total synthesis of (-)-kendomycin exploiting a Petasis-Ferrier rearrangement/ring-closing olefin metathesis strategy.

A convergent stereocontrolled total synthesis of (-)-kendomycin (1) has been achieved. The synthesis proceeds with a longest linear sequence of 21 steps, beginning with commercially available 2,4-dimethoxy-3-methylbenzaldehyde (12). Highlights of the synthesis include an effective Petasis-Ferrier union/rearrangement tactic to construct the sterically encumbered tetrahydropyran ring, a ring-closing metathesis to generate the C(4a-13-20a) macrocycle, an effective epoxidation/deoxygenation sequence to isomerize the C(13,14) olefin, and a biomimetic quinone-methide-lactol assembly to complete the synthesis.

Total synthesis of (-)-kendomycin exploiting a Petasis-Ferrier rearrangement/ring-closing olefin metathesis synthetic strategy.

The total synthesis of (-)-kendomycin (1), a novel macrocyclic polyketide with antibacterial and antitumor activity, was achieved in 21 steps (longest linear sequence) exploiting an effective Petasis-Ferrier union/rearrangement tactic to construct the tetrahydropyran ring, a ring-closing metathesis to generate the macrocycle, and a biomimetic quinone-methide-lactol assembly.

Crystallographic study of inhibitors of tRNA-guanine transglycosylase suggests a new structure-based pharmacophore for virtual screening.

The enzyme tRNA-guanine transglycosylase (TGT) is involved in the pathogenicity of Shigellae. As the crystal structure of this protein is known, it is a putative target for the structure-based design of inhibitors. Here we report a crystallographic study of several new ligands exhibiting a 2,6-diamino-3H-quinazolin-4-one scaffold, which has been shown recently to be a promising template for TGT-inhibitors. Crystal structure analysis of these complexes has revealed an unexpected movement of the side-chain of Asp102. A detailed analysis of the water network disrupted by this rotation has lead to the derivation of a new composite pharmacophore. A virtual screening has been performed based on this pharmacophore hypothesis and several new inhibitors of micromolar binding affinity with new skeletons have been discovered.