CCNE1 amplification is synthetic lethal with PKMYT1 kinase inhibition.

Amplification of the CCNE1 locus on chromosome 19q12 is prevalent in multiple tumour types, particularly in high-grade serous ovarian cancer, uterine tumours and gastro-oesophageal cancers, where high cyclin E levels are associated with genome instability, whole-genome doubling and resistance to cytotoxic and targeted therapies1-4. To uncover therapeutic targets for tumours with CCNE1 amplification, we undertook genome-scale CRISPR-Cas9-based synthetic lethality screens in cellular models of CCNE1 amplification. Here we report that increasing CCNE1 dosage engenders a vulnerability to the inhibition of the PKMYT1 kinase, a negative regulator of CDK1. To inhibit PKMYT1, we developed RP-6306, an orally bioavailable and selective inhibitor that shows single-agent activity and durable tumour regressions when combined with gemcitabine in models of CCNE1 amplification. RP-6306 treatment causes unscheduled activation of CDK1 selectively in CCNE1-overexpressing cells, promoting early mitosis in cells undergoing DNA synthesis. CCNE1 overexpression disrupts CDK1 homeostasis at least in part through an early activation of the MMB-FOXM1 mitotic transcriptional program. We conclude that PKMYT1 inhibition is a promising therapeutic strategy for CCNE1-amplified cancers.

Identification and Biosynthesis of an N-Glucuronide Metabolite of Camonsertib.

Camonsertib is a novel ATR kinase inhibitor in clinical development for advanced cancers targeting sensitizing mutations. This article describes the identification and biosynthesis of an N-glucuronide metabolite of camonsertib. This metabolite was first observed in human hepatocyte incubations and was subsequently isolated to determine the structure, evaluate its stability as part of bioanalytical method development and for use as a standard for estimating its concentration in Phase I samples. The N-glucuronide was scaled-up using a purified bacterial culture preparation and was subsequently isolated using preparative chromatography. The bacterial culture generated sufficient material of the glucuronide to allow for one- and two-dimensional 1H and 13C NMR structural elucidation and further bioanalytical characterization. The NOE data combined with the gradient HMBC experiment and molecular modeling, strongly suggests that the point of attachment of the glucuronide results in the formation of (2S,3S,4S,5R,6R)-3,4,5-trihydroxy-6-(5-(4-((1R,3r,5S)-3-hydroxy-8-oxabicyclo[3.2.1]octan-3-yl)-6-((R)-3-methylmorpholino)-1H-pyrazolo[3,4-b]pyridin-1-yl)-1H-pyrazol-1-yl)tetrahydro-2H-pyran-2-carboxylic acid. Significance Statement This is the first report of a glucuronide metabolite of camonsertib formed by human hepatocyte incubations. This study reveals the structure of an N-glucuronide metabolite of camonsertib using detailed elucidation by one- and two-dimensional NMR after scale-up using a novel bacterial culture approach yielding significant quantities of a purified metabolite.

[Appleby procedure - an option for surgical treatment of pancreatic body tumour infiltrating the celiac axis]. / Appleby-mutét − lehetoség truncus coeliacust infiltráló pancreastest tumor sebészi kezelésére.

CASE PRESENTATION: After neoadjuvant oncological therapy the surgical treatment of distal pancreatic tumour - infiltrating the celiac axis and the stomach - was reported. During the operation resection of the trunc, distal pancreatectomy, splenectomy, total gastrectomy, resection of the left adrenal gland and cholecystectomy were carried out. The patient's clinical course was uneventful, only transient alteration of liver functions was detected. Histological work-up revealed R1 resection, so adjuvant oncological therapy was decided. DISCUSSION: Distal pancreatic tumours are frequently inoperable. Infiltration of the celiac axis was similarly considered, however there is a chance for radical operation by the resection of the trunc, when the pancreaticoduodenal arcade will provide the arterial blood supply to the liver. Based on the above case the operative technique and the relevant questions were discussed. In pancreatic tumour and arterial infiltration the preoperative chemotherapy is absolutely recommended, because there is a chance for radical surgery in case of good response.

[Resection of liver and abdominal wall metastasis 11 years after pancreatoduodenectomy. Case report]. / Metasztázis miatt végzett máj- és hasfalreszekció 11 évvel a pancreatoduodenectomia után.

Pancreatic cancer has adverse prognosis. Disease recurrence is typical and it occurs mainly within the first 2 years postoperatively. However late and soliter metastases are rare. This case report shows the history of a male patient, who was radically operated on for pancreatic cancer. 11 years later a solitary liver metastasis has developed and it was completely removed by resection. 1 year postoperatively the patient is doing well. Our case demonstrates that in patients after resection for pancreatic cancer, redo surgery might be justified in case of late and isolated metastasis. Orv Hetil. 2017; 158(28): 1109-1111.

Pancreatojejunostomy with modified purse-string suture technique.

PURPOSE: Despite many efforts, pancreatic fistula remains the most troublesome complication following pancreatic resections, especially in case of anastomosis made with soft pancreatic tissue. The purpose of the authors was to show their modification of purse-string pancreatodigestive anastomosis and the results obtained. METHODS: Between January 2013 and June 2015, the technique was applied in 49 patients; one purse-string suture and two U-shaped mattress sutures were used to create the pancreatojejunal anastomosis. In case of soft pancreatic parenchyma, an external stent was temporarily left in the main pancreatic duct. The most frequent pathology was pancreatic cancer, and a pylorus-preserving Whipple procedure was mostly done. RESULTS: Postoperative early morbidity rate was 35 %. There were two fistulas, one grade A fistula from a fibrotic pancreas (4.2 %) and one grade B in case of a soft pancreas (4 %). However, there was no reoperation and mortality. CONCLUSIONS: According to favorable results, the modification of the purse-string suture technique makes this method even safer.

Smooth muscle-depressant activity of AP-18, a putative TRPA1 antagonist in the guinea pig intestine.

AP-18, a putative antagonist at TRPA1 receptor/ion channel, caused smooth muscle relaxation at 10-100 µmol/l. It inhibited cholinergic twitch responses evoked by electrical field stimulation of cholinergic nerves as well as contractions in response to acetylcholine and histamine in the guinea pig small intestine. AP-18 (30 µmol/l) blocked spontaneous contractions of longitudinal strips of human jejunum. It is concluded that AP-18 may have limited value in studying TRPA1-mediated responses in smooth muscles and should probably be used with care in other preparations because of possible nonspecific effects.

PKMYT1 is a Marker of Treatment Response and a Therapeutic Target for CDK4/6 Inhibitor-Resistance in ER+ Breast Cancer.

Endocrine therapies (ET) with CDK4/6 inhibition are the standard treatment for estrogen receptor-α-positive (ER+) breast cancer, however drug resistance is common. In this study, proteogenomic analyses of 22 ER+ breast cancer patient-derived xenografts (PDXs) demonstrated that PKMYT1, a WEE1 homolog, is estradiol (E2) regulated in E2-dependent PDXs and constitutively expressed when growth is E2-independent. In clinical samples, high PKMYT1 mRNA levels associated with resistance to both ET and CDK4/6 inhibition. The PKMYT1 inhibitor lunresertib (RP-6306) with gemcitabine selectively and synergistically reduced the viability of ET and palbociclib-resistant ER+ breast cancer cells without functional p53. In vitro the combination increased DNA damage and apoptosis. In palbociclib-resistant, TP53 mutant PDX organoids and xenografts, RP-6306 with low-dose gemcitabine induced greater tumor volume reduction compared to treatment with either single agent. Our study demonstrates the clinical potential of RP-6306 in combination with gemcitabine for ET and CDK4/6 inhibitor resistant TP53 mutant ER+ breast cancer.

Discovery of the Potent and Selective ATR Inhibitor Camonsertib (RP-3500).

ATR is a key kinase in the DNA-damage response (DDR) that is synthetic lethal with several other DDR proteins, making it an attractive target for the treatment of genetically selected solid tumors. Herein we describe the discovery of a novel ATR inhibitor guided by a pharmacophore model to position a key hydrogen bond. Optimization was driven by potency and selectivity over the related kinase mTOR, resulting in the identification of camonsertib (RP-3500) with high potency and excellent ADME properties. Preclinical evaluation focused on the impact of camonsertib on myelosuppression, and an exploration of intermittent dosing schedules to allow recovery of the erythroid compartment and mitigate anemia. Camonsertib is currently undergoing clinical evaluation both as a single agent and in combination with talazoparib, olaparib, niraparib, lunresertib, or gemcitabine (NCT04497116, NCT04972110, NCT04855656). A preliminary recommended phase 2 dose for monotherapy was identified as 160 mg QD given 3 days/week.

Rupture of pseudoaneurysm into hepaticojejunal anastomosis: report of three cases.

Bleeding complications are less common after major pancreatic resections. They are more often associated with pancreatic fistula. The authors present three cases of a unique situation, when pseudoaneurysm of the common hepatic artery ruptured into the hepaticojejunal anastomosis, causing massive upper gastrointestinal haemorrhage. The basic operations were pancreatic resections for malignancy. In two out of the three cases intra-abdominal infection developed postoperatively. Computer tomographic angiography was a useful tool to reveal the source of bleeding. A re-do surgery was carried out whereby bleeding control was achieved with haemostatic sutures and the biliodigestive anastomoses were also repaired. Re-bleeding did not occur postoperatively and the liver function remained normal. The authors emphasize that in case of severe gastrointestinal bleeding after pancreatic resection, this rare entity ought to be taken into account in the differential diagnosis.

Ganglioneuroma in the papilla of Vater with neurofibromatosis type 1: report of a case.

Ganglioneuromas (GNs) are rare benign tumors and their association with neurofibromatosis type 1 (NF-1) is especially uncommon. We report in this article the case of a young woman, subjected to diagnostic work-up because of abdominal pain. Endoscopy and histology revealed not only a GN in the papilla of Vater, but also NF-1. Because of the size and macroscopic features of the lesion, we performed pancreatoduodenectomy, from which she recovered uneventfully. Histological examination of the resected tumor confirmed a diagnosis of GN.

[Pancreatojejunostomy--with purse-string suture]. / Pancreatojejunostomia - dohányzacskóöltéssel.

INTRODUCTION: Pancreatic fistula is one of the most relevant complications following pancreatoduodenectomies. Significant effort has been made to decrease it. The aim of the authors was to show a pancreatojejunal anastomosis combined with purse-string suture, and report the first experiences, as well. MATERIAL AND METHODS: The implantation pancreatojejunostomy - which has been applied by the authors since 2003 - was modified, that the remnant of the pancreas was fixed in the jejunum with one purse-string and two mattress sutures. In case of a soft pancreas the Wirsungian duct was stented, then the vein canule was pulled out to the outside throught the afferent jejunal limb. The method was applied in seven patients during pylorus-preserving pancreatoduodenectomy performed for neoplasm. RESULTS: In the postoperative period there were two complications in two patients noted (a bleeding ulcer developed in the region of the duodenojejunostomy and a transient confusion). However there was no pancreatic fistula, reoperation or early mortality detected. CONCLUSIONS: While major conclusions can not be drawn due to the relatively small number of cases, this method seems promising and it is worth to carry out further trials.

[Experiences with central pancreatectomy]. / Centrális pancreatectomiával szerzett tapasztalataink.

INTRODUCTION: The authors report their experience with central pancreatectomy and also summarize relevant literature data. MATERIAL AND METHODS: Central pancreatectomies were performed in 7 patients for benign or low-grade malignant pancreatic neoplasms, or pancreatic rupture in one patient. Most frequently applied anastomosis was between the distal part of the pancreas and a Roux-en-Y limb, while the proximal cut surface was closed with sutures, and the suture line was covered with a limb. RESULTS: There were three complications (37%), but reoperation didn't need to be performed and none of the patients died. We did not detect any deterioration in the exocrine or endocrine function during the follow-up period. CONCLUSIONS: Central pancreatectomy is a safe procedure with excellent functional results, if both the indication and the applied technique are chosen appropriately.

[Our efforts to decrease surgical complications following pancreatic resections]. / Törekvéseink a pancreasresectiókat követo sebészi szövodmények csökkentésére.

INTRODUCTION: The most frequent surgical complications following pancreatic resections are pancreatic fistula and delayed gastric emptying. The aim of the authors was to analyse these complications in their own practice. MATERIAL AND METHODS: Clinical data of 287 patients were reviewed, who were radically operated on for malignant pancreatic or periampullary tumours during 14 years period. The most common neoplasm was pancreatic adenocarcinoma, located in the head of the pancreas. Pylorus-preserving pancreatoduodenectomy was most frequently performed. In the early period pancreatogastrostomy and double-layer pancreatojejunostomy were preferred during the reconstruction, as well as retrocolic duodeno-, and gastrojejunostomy, respectively. Later the authors turned to the single-layer implantation pancreatojejunostomy and to the antecolic reconstruction, the latter was completed with Braun anastomosis. RESULTS: In the postoperative course complications occurred in 39%, reoperation was done in 5.6%, and the early mortality rate was 3.8%. The rate of pancreatic fistula decreased to 5.9% following single-layer pancreatojejunostomy, and the difference was significant compared to the 17.6% rate after pancreatogastrostomy. Due to the antecolic reconstruction the frequency of delayed gastric emptying has reduced from 10.2% to 2.1%, which is a statistically significant difference. CONCLUSIONS: As a result of changes in the surgical techniques during the 14 years period, the frequency of pancreatic fistula and delayed gastic emptying has dramatically decreased, which underlines the need of continuous progress in surgical methods.

Discovery of an Orally Bioavailable and Selective PKMYT1 Inhibitor, RP-6306.

PKMYT1 is a regulator of CDK1 phosphorylation and is a compelling therapeutic target for the treatment of certain types of DNA damage response cancers due to its established synthetic lethal relationship with CCNE1 amplification. To date, no selective inhibitors have been reported for this kinase that would allow for investigation of the pharmacological role of PKMYT1. To address this need compound 1 was identified as a weak PKMYT1 inhibitor. Introduction of a dimethylphenol increased potency on PKMYT1. These dimethylphenol analogs were found to exist as atropisomers that could be separated and profiled as single enantiomers. Structure-based drug design enabled optimization of cell-based potency. Parallel optimization of ADME properties led to the identification of potent and selective inhibitors of PKMYT1. RP-6306 inhibits CCNE1-amplified tumor cell growth in several preclinical xenograft models. The first-in-class clinical candidate RP-6306 is currently being evaluated in Phase 1 clinical trials for treatment of various solid tumors.

RP-3500: A Novel, Potent, and Selective ATR Inhibitor that is Effective in Preclinical Models as a Monotherapy and in Combination with PARP Inhibitors.

Ataxia telangiectasia and Rad3-related (ATR) kinase protects genome integrity during DNA replication. RP-3500 is a novel, orally bioavailable clinical-stage ATR kinase inhibitor (NCT04497116). RP-3500 is highly potent with IC50 values of 1.0 and 0.33 nmol/L in biochemical and cell-based assays, respectively. RP-3500 is highly selective for ATR with 30-fold selectivity over mammalian target of rapamycin (mTOR) and more than 2,000-fold selectivity over ataxia telangiectasia mutated (ATM), DNA-dependent protein kinase (DNA-PK), and phosphatidylinositol 3-kinase alpha (PI3Kα) kinases. In vivo, RP-3500 treatment results in potent single-agent efficacy and/or tumor regression in multiple xenograft models at minimum effective doses (MED) of 5 to 7 mg/kg once daily. Pharmacodynamic assessments validate target engagement, with dose-proportional tumor inhibition of phosphorylated checkpoint kinase 1 (pCHK1) (IC80 = 18.6 nmol/L) and induction of phosphorylated H2A.X variant histone (γH2AX), phosphorylated DNA-PK catalytic subunit (pDNA-PKcs), and phosphorylated KRAB-associated protein 1 (pKAP1). RP-3500 exposure at MED indicates that circulating free plasma levels above the in vivo tumor IC80 for 10 to 12 hours are sufficient for efficacy on a continuous schedule. However, short-duration intermittent (weekly 3 days on/4 days off) dosing schedules as monotherapy or given concomitantly with reduced doses of olaparib or niraparib, maximize tumor growth inhibition while minimizing the impact on red blood cell depletion, emphasizing the reversible nature of erythroid toxicity with RP-3500 and demonstrating superior efficacy compared with sequential treatment. These results provide a strong preclinical rationale to support ongoing clinical investigation of the novel ATR inhibitor, RP-3500, on an intermittent schedule as a monotherapy and in combination with PARP inhibitors as a potential means of maximizing clinical benefit.

Identification of RP-6685, an Orally Bioavailable Compound that Inhibits the DNA Polymerase Activity of Polθ.

DNA polymerase theta (Polθ) is an attractive synthetic lethal target for drug discovery, predicted to be efficacious against breast and ovarian cancers harboring BRCA-mutant alleles. Here, we describe our hit-to-lead efforts in search of a selective inhibitor of human Polθ (encoded by POLQ). A high-throughput screening campaign of 350,000 compounds identified an 11 micromolar hit, giving rise to the N2-substituted fused pyrazolo series, which was validated by biophysical methods. Structure-based drug design efforts along with optimization of cellular potency and ADME ultimately led to the identification of RP-6685: a potent, selective, and orally bioavailable Polθ inhibitor that showed in vivo efficacy in an HCT116 BRCA2-/- mouse tumor xenograft model.

Impact of passive permeability and gut efflux transport on the oral bioavailability of novel series of piperidine-based renin inhibitors in rodents.

An oral bioavailability issue encountered during the course of lead optimization in the renin program is described herein. The low F(po) of pyridone analogs was shown to be caused by a combination of poor passive permeability and gut efflux transport. Substitution of pyridone ring for a more lipophilic moiety (logD>1.7) had minimal effect on rMdr1a transport but led to increased passive permeability (P(app)>10 × 10(-6) cm/s), which contributed to overwhelm gut transporters and increase rat F(po). LogD and in vitro passive permeability determination were found to be key in guiding SAR and improve oral exposure of renin inhibitors.

Middle segmental pancreatic resection--a single-centre experience.

BACKGROUND/AIMS: A single-centre experience gained by middle segmental pancreatic resection and a brief survey of technique and indications are reported. METHODOLOGY: During the past 7 years 7 middle segmental pancreatic resections were performed for benign and low-grade malignant pancreatic lesions and in 1 case for pancreatic trauma. The preferred method was anastomosing the distal remnant to a Roux-en-Y limb, closure of the proximal cut end with sutures and in the last 4 patients covering this suture line with the limb. RESULTS: There were 3 complications out of 8 cases (37%) and the surgical morbidity rate was 12%. It did not come to reoperation and lethal outcome. During the follow-up time both the endocrine and exocrine functions remained normal in all patients. CONCLUSIONS: Middle segmental pancreatic resection could be carried out with an acceptable morbidity rate. However the proper indication and surgical technique are important factors in achieving advantageous results.

[Not Available]. / Új típusú, retrograd dissectio pancreatoduodenectomia során - korai tapasztalataink.

The authors emphasize that late results following surgery for pancreatic cancer can be improved by increasing the rate of R0 resections. Therefore, they propose a new method for pancreatic head resection, which starts with the dissection of the uncinate process and continues in a caudo-cranial direction (retrograde). Thus the superior mesenteric artery comes into view at the beginning, and the peripancreatic tissues can be removed completely along the vessel consequently. This method can potentially decrease the risk of the bleeding and major vessel injury. The authors carried out six pancreatic head resections with the technique mentioned above, and histology revealed R0 resection in all six cases. Non-traditional, retrograde dissection of the pancreatic head is a recommended method which is supported by literature data as well as the authors' own experience.

The CIP2A-TOPBP1 axis safeguards chromosome stability and is a synthetic lethal target for BRCA-mutated cancer.

BRCA1/2-mutated cancer cells adapt to the genome instability caused by their deficiency in homologous recombination (HR). Identification of these adaptive mechanisms may provide therapeutic strategies to target tumors caused by the loss of these genes. In the present study, we report genome-scale CRISPR-Cas9 synthetic lethality screens in isogenic pairs of BRCA1- and BRCA2-deficient cells and identify CIP2A as an essential gene in BRCA1- and BRCA2-mutated cells. CIP2A is cytoplasmic in interphase but, in mitosis, accumulates at DNA lesions as part of a complex with TOPBP1, a multifunctional genome stability factor. Unlike PARP inhibition, CIP2A deficiency does not cause accumulation of replication-associated DNA lesions that require HR for their repair. In BRCA-deficient cells, the CIP2A-TOPBP1 complex prevents lethal mis-segregation of acentric chromosomes that arises from impaired DNA synthesis. Finally, physical disruption of the CIP2A-TOPBP1 complex is highly deleterious in BRCA-deficient tumors, indicating that CIP2A represents an attractive synthetic lethal therapeutic target for BRCA1- and BRCA2-mutated cancers.