Discovery of WRN inhibitor HRO761 with synthetic lethality in MSI cancers

The Werner syndrome RecQ helicase WRN was identified as a synthetic lethal target in cancer cells with microsatellite instability (MSI) by several genetic screens1-6. Despite advances in treatment with immune checkpoint inhibitors7-10, there is an unmet need in the treatment of MSI cancers11-14. Here we report the structural, biochemical, cellular and pharmacological characterization of the clinical-stage WRN helicase inhibitor HRO761, which was identified through an innovative hit-finding and lead-optimization strategy. HRO761 is a potent, selective, allosteric WRN inhibitor that binds at the interface of the D1 and D2 helicase domains, locking WRN in an inactive conformation. Pharmacological inhibition by HRO761 recapitulated the phenotype observed by WRN genetic suppression, leading to DNA damage and inhibition of tumour cell growth selectively in MSI cells in a p53-independent manner. Moreover, HRO761 led to WRN degradation in MSI cells but not in microsatellite-stable cells. Oral treatment with HRO761 resulted in dose-dependent in vivo DNA damage induction and tumour growth inhibition in MSI cell- and patient-derived xenograft models. These findings represent preclinical pharmacological validation of WRN as a therapeutic target in MSI cancers. A clinical trial with HRO761 (NCT05838768) is ongoing to assess the safety, tolerability and preliminary anti-tumour activity in patients with MSI colorectal cancer and other MSI solid tumours.

Long-term cosmetic results of video-assisted thyroidectomy: a comparison with conventional surgery

PURPOSE

We present the long-term cosmetic results of the video-assisted thyroidectomy (MIVAT) in comparison to the conventional operation.

METHODS

Forty-eight patients (four males, 44 females; mean age 47.4 ± 12.5 years) constituted the video-assisted group (VA-Group). These were compared with 48 patients (10 males, 38 females; mean age 47.4 ± 12.5 years) operated by conventional surgery (C-Group). The patients were selected from all thyroid operations performed between January 2016 and June 2017. Patient Scar Assessment Scale (PSAS) and Observer Scar Assessment Scale (OSAS) were used for the evaluation performed by an independent surgeon. Both scales contained six items scored numerically on a ten-step scale ranging from 1 (normal skin) to 10 (worst result). Moreover, photos of all scars were taken and analyzed by six team surgeons using modified OSAS.

RESULTS

The mean follow-up time was 31.7 ± 6.4 months for the MIVAT group and 32.9 ± 4.6 months for the conventional group (p = 0.39). The mean scar length in the VA-Group was 2.6 cm vs. 3.8 cm in the C-Group (p < 0.0001). The total score of PSAS was 9.93 (6-35) for MIVAT and 9.72 (6-29) for conventional thyroidectomy (p = 0.22). The total OSAS score by the independent surgeon showed a better cosmetic outcome for conventional surgery (13.19 vs. 12.33; p = 0.01). The total OSAS score by the six team surgeons did not differ between both groups in five of six ratings; one surgeon favored MIVAT (12.2 vs. 13.6; p = 0.04).

CONCLUSIONS

This study does not find cosmetic advantages of minimally invasive video-assisted thyroidectomy compared to conventional thyroidectomy.

Discovery of LYS006, a Potent and Highly Selective Inhibitor of Leukotriene A4 Hydrolase

The cytosolic metalloenzyme leukotriene A4 hydrolase (LTA4H) is the final and rate-limiting enzyme in the biosynthesis of pro-inflammatory leukotriene B4 (LTB4). Preclinical studies have validated this enzyme as an attractive drug target in chronic inflammatory diseases. Despite several attempts, no LTA4H inhibitor has reached the market, yet. Herein, we disclose the discovery and preclinical profile of LYS006, a highly potent and selective LTA4H inhibitor. A focused fragment screen identified hits that could be cocrystallized with LTA4H and inspired a fragment merging. Further optimization led to chiral amino acids and ultimately to LYS006, a picomolar LTA4H inhibitor with exquisite whole blood potency and long-lasting pharmacodynamic effects. Due to its high selectivity and its ability to fully suppress LTB4 generation at low exposures in vivo, LYS006 has the potential for a best-in-class LTA4H inhibitor and is currently investigated in phase II clinical trials in inflammatory acne, hidradenitis suppurativa, ulcerative colitis, and NASH.

Detection of chronic lung allograft dysfunction using ventilation-weighted Fourier decomposition MRI

Chronic lung allograft dysfunction (CLAD) remains the leading cause of morbidity and mortality after lung transplantation. Diagnosis requires spirometric change, which becomes increasingly difficult with advancing CLAD. Fourier decomposition magnetic resonance imaging (FD-MRI) permits acquisition of ventilated-weighted images during free-breathing. This study evaluates FD-MRI in detecting CLAD in selected patients after bilateral lung transplantation (DLTx). DLTx recipients demonstrating CLAD at various stages participated. Radiologists remained blinded to clinical status until completion of image analysis. Image acquisition used a 1.5-T MR scanner using a spoiled gradient echo sequence. After FD processing and regional fractional ventilation (RFV) quantification, the volume defect percentage at 2 thresholds (VDP_1,2 ), median lung RFV and quartile coefficient of dispersion (QCD) were calculated. Sixty-two patients participated. CLAD was present in 29/62 (47%) patients, of whom 17/62 (27%) had forced expiratory volume in 1 second ≤65% at image acquisition. VDP₁ was higher among these participants compared to other groups (P < .001). Increased VDP₁ was associated with subsequent graft loss, with values >2% showing reduced survival, independent of degree of graft dysfunction (P = .005). VDP₂ discriminated between presence or absence of CLAD (area under the curve = 0.71; P = .03). QCD increased significantly with advancing disease (P < .001). In conclusion, FD-MRI-derived parameters demonstrate potential in quantitative CLAD diagnosis and assessment after DLTx.

[Chronic thromboembolic pulmonary hypertension: Recommendations of the Cologne Consensus Conference 2016]

The 2015 European Guidelines on Pulmonary Hypertension did not cover only pulmonary arterial hypertension (PAH), but also other significant subgroups of pulmonary hypertension (PH). In June 2016, a Consensus Conference organized by the PH working groups of the German Society of Cardiology (DGK), the German Society of Respiratory Medicine (DGP) and the German Society of Pediatric Cardiology (DGPK) was held in Cologne, Germany to discuss open and controversial issues surrounding the practical implementation of the European Guidelines. Several working groups were initiated, one of which was dedicated to the diagnosis and treatment of chronic thromboembolic pulmonary hypertension (CTEPH). In every patient with PH of unknown cause CTEPH should be excluded. The primary treatment option is surgical pulmonary endarterectomy (PEA) in a specialized multidisciplinary CTEPH center. Inoperable patients or patients with persistent or recurrent CTEPH after PEA are candidates for targeted drug therapy. For balloon pulmonary angioplasty (BPA), there is currently only limited experience. This option - as PEA - is reserved to specialized centers with expertise for this treatment method. In addition, a brief overview is given on pulmonary artery sarcoma, since its surgical treatment is often analogous to PEA. The recommendations of this working group are summarized in the present paper.

Diagnostic value and clinical impact of complementary CT scan prior to surgery for non-localized primary hyperparathyroidism

INTRODUCTION

Successful localization is mandatory for focused parathyroidectomy. If ultrasound and sestamibi scan are negative, bilateral neck exploration is necessary. We examined the contribution of complementary computed tomography (CT) scan to identify the affected parathyroid gland.

METHODS

Between November 1999 and April 2014, 25 patients (20 females and 5 males; mean age 67 ± 11 years) with negative or dubious standard imaging (ultrasound and sestamibi scan) underwent CT scan prior to parathyroidectomy and were included in this study. Fifteen patients had had previous neck surgery for parathyroidectomy (n = 11) or thyroidectomy (n = 4). Thin-slice CT (n = 9) or four-dimensional (4D) CT imaging (n = 16) was used. Cure was defined as >50 % post-excision fall of intraoperatively measured parathyroid hormone or fall into the normal range, confirmed by normocalcaemia at least 6 months after surgery.

RESULTS

Preoperative CT scan provided correct localization in 13 out of 25 patients (52 %) and was false positive once. Parathyroidectomy was performed by a focused approach in 11 of these 13 patients as well as in 1 patient guided by intraoperatively measured parathyroid hormone (ioPTH). Thirteen patients required bilateral neck exploration. The cure rate was 96 % (24/25 patients). One patient has persistent primary hyperparathyroidism (pHPT) and one a recurrent disease. Six patients presented a multiglandular disease.

CONCLUSION

A CT scan identifies about half of abnormal parathyroid glands missed by conventional imaging and allows focused surgery in selected cases.

Closing the gap: discrimination of the expression profile of HLA questionable alleles by a cytokine-induced secretion approach using HLA-A*32:11Q

Matching of human leukocyte antigen (HLA) alleles between donors and recipients plays a major role in hematopoietic stem cell transplantation (HSCT). Null or questionably expressed HLA allelic variants are a major issue in HLA matching, because the aberrant expression of such alleles can have a major impact on the outcome of HSCT and/or its complications such as graft-versus-host disease. The goal of this study was to investigate the potential of a recently developed cytokine-induced secretion assay to differentiate the expression levels of HLA-A*32:11Q (questionable) into a null (N) or low (L) expression variant. An amino acid mutation at position 164 of HLA-A*32:11Q disrupts the disulfide bridge in the α2 domain. HLA-A*32:11Q is not detectable by standard microlymphocytotoxicity assay. To this end, we cloned soluble HLA-A*32:11Q and a reference allele (HLA-A*32:01) into expression vectors and transfected/transduced HEK293 and K562 cells. Allele-expressing K562 cells were simultaneously transfected/transduced with a β2-microglobulin (B2M)-encoding vector to ensure the intact HLA structure with B2M. After treatment with proinflammatory cytokines, secreted soluble HLA molecules were determined by enzyme-linked immunosorbent assay in the supernatant and intracellular accumulation of the recombinant proteins by flow cytometry. HLA-A*32:11Q was nearly undetectable in untreated transfectants. Cytokine treatment increased the secretion of HLA-A*32:11Q to detectable levels and resulted in intracellular accumulation of the allele. There was no difference in mRNA transcription between the A*32 alleles. On the basis of these results, we recommend reclassification of HLA-A*32:11Q as a low expression (L) variant.