Pan-KRAS inhibitors suppress proliferation through feedback regulation in pancreatic ductal adenocarcinoma

Patient-derived organoids from pancreatic cancer after pancreatectomy: Feasibility and organoid take rate in treatment-naïve periampullary tumors

BACKGROUND/OBJECTIVE

Patient-derived organoids (PDOs) have emerged as essential for ex vivo modelling for pancreatic cancer (PDAC) but reports on efficacy and organoid take rate are scarce. This study aimed to assess the feasibility of establishing PDOs from resected specimens in periampullary tumors.

METHODS

Patients undergoing surgery for suspected periampullary cancer were included. PDO protocol amendments were tested, with organoid take rate as outcome measure. Samples from resected specimens were processed and expanded per protocol. Pooled estimate of take rates of PDOs in PDAC was derived from literature search.

RESULTS

23 specimens were available for PDO, of which 10 were PDAC. In 15 patients other histopathology was found: neuroendocrine tumors (NET; n = 2), neuroendocrine carcinoma (NEC; n = 1), intraductal papillary mucinous neoplasm (IPMN; n = 4), distal cholangiocarcinoma (dCCA; n = 1), ampullary carcinoma (n = 1), duodenal carcinoma (n = 1), intra-ampullary papillary tubular neoplasm (IAPN; n = 1), indeterminate PDAC/ampullary carcinoma(n = 1), and one patient with chronic inflammation/fibrosis. Organoid cultures were grown from 7 of 10 (70 %) PDAC, 1 dCCA, 1 NEC, 1 duodenal carcinoma, 1 indeterminate tumor type and 1 ampullary carcinoma (i.e. 12/18; 66.7 % across periampullary cancers). Overall take rate of PDOs was 12 of 23 (52.2 %) for all tumors. A pooled mean estimate PDO take rate of 62.3 % (95 % CI:54.8-69.3 %) was reported across available studies in the literature.

CONCLUSION

In the current study, we found that PDOs could be established from resected pancreatic tumors in over half of resected periampullary tumors, and highest in PDACs. As such, generating a pancreatic cancer PDO biobank for translational research was feasible after cryopreservation.

KRAS inhibitors in drug resistance and potential for combination therapy

Kirsten Rat Sarcoma (KRAS) is a potent target for cancer therapy because it acts as a signaling hub, engaging in various signaling pathways and regulating a number of cellular functions like cell differentiation, proliferation, and survival. Recently, an emergency approval from the US-FDA has been issued for KRASG12C inhibitors (sotorasib and adagrasib) for metastatic lung cancer treatment. However, clinical studies on covalent KRASG12C inhibitors have rapidly confronted resistance in patients. Many methods are being assessed to overcome this resistance, along with various combinatorial clinical studies that are in process. Moreover, because KRASG12D and KRASG12V are more common than KRASG12C, focus must be placed on the therapeutic strategies for this type of patient, along with sustained efforts in research on these targets. In the present review, we try to focus on various strategies to overcome rapid resistance through the use of combinational treatments to improve the activity of KRASG12C inhibitors.

EUS-guided biopsies versus surgical specimens for establishing patient-derived pancreatic cancer organoids: a systematic review and meta-analysis

BACKGROUND AND AIMS

Patient-derived tumor organoids (PDTOs) are a promising new disease model in pancreatic cancer for use in personalized medicine. However, the overall success rate (SR) of establishing these cultures from EUS-guided biopsies is unknown.

METHODS

We searched relevant database publications reporting SRs of PDTO establishment from pancreatic cancer. The primary outcome was SR stratified on tissue acquisition method (EUS-guided biopsies, percutaneous biopsies, and surgical specimens).

RESULTS

Twenty-four studies were identified that included 1053 attempts at establishing PDTOs. Overall SR was 63% (95% confidence interval [CI], 54%-72%). Pooled SRs of PDTO establishment from EUS-guided biopsies, percutaneous biopsies, and surgical specimens were 60% (95% CI, 43%-76%), 36% (95% CI, 14%-61%), and 62% (95% CI, 48%-75%), respectively, and did not differ significantly (P = .1975).

CONCLUSION

The SR of PDTO establishment from EUS-guided biopsies is comparable to that from surgical specimens. Both techniques are suitable for tissue acquisition for PDTOs in clinical and research settings. (PROSPERO registration number: CRD42023425121.).

Efficacy of immune checkpoint inhibitors in advanced non-small cell lung cancer patients with rare KRAS mutations: a real-world retrospective study

Background

Kirsten rat sarcoma homolog (KRAS) mutations are one of the key drivers in non-small cell lung cancer (NSCLC) and FDA-approved specific inhibitors of KRAS-G12C mutation are available clinically. However, inhibitors of certain KRAS mutation subtypes remain unavailable, especially rare KRAS mutations including G13C, G13D, and Q61H. In this study, we retrospectively investigated the outcomes of NSCLC patients with rare KRAS-mutation to determine if they may benefit from immune checkpoint inhibitors (ICIs).

Methods

Our retrospective study involved 240 advanced NSCLC patients with KRAS mutations, who visited Shanghai Chest Hospital from July 2018 to July 2021. Complete clinical and pathological data were recorded and progression-free survival (PFS) and overall survival (OS) were adopted as primary endpoints.

Results

The median follow-up time was 36.5 months (range, 30.8-42.1 months) and the median OS was 9.7 months (range, 7.6-11.8 months). Of the 240 patients evaluated, 130 (54.2%) received chemotherapy and 110 (45.8%) received ICI-based treatment. Among the patients who received chemotherapy, patients with rare KRAS-mutations presented worse survival outcomes (median PFS, 3.4 vs. 4.1 months, P=0.047; median OS, 5.2 vs. 7.1 months, P=0.02) than conventional KRAS-mutant patients. PFS and OS of rare KRAS-mutation patients were prolonged after immunotherapy (median PFS 7.3 vs. 3.4 months, P<0.001; median OS, 13.3 vs. 5.2 months, P<0.001) and had no significant difference compared with conventional KRAS-mutant patients, in part of them whose programmed death-ligand 1 (PD-L1) expression data before immunotherapy were available (n=72), patients with a higher rate of PD-L1 positive tumor cells (≥50%) presented elevated PFS and OS.

Conclusions

Despite having potential survival disadvantage compared with other NSCLC patients, rare KRAS-mutant patients (other than G12A, C, D, V) could benefit specifically from ICI-based therapy and survival outcomes are correlated with PD-L1 expression.

Defining the KRAS- and ERK-dependent transcriptome in KRAS-mutant cancers

How the KRAS oncogene drives cancer growth remains poorly understood. Therefore, we established a systemwide portrait of KRAS- and extracellular signal-regulated kinase (ERK)-dependent gene transcription in KRAS-mutant cancer to delineate the molecular mechanisms of growth and of inhibitor resistance. Unexpectedly, our KRAS-dependent gene signature diverges substantially from the frequently cited Hallmark KRAS signaling gene signature, is driven predominantly through the ERK mitogen-activated protein kinase (MAPK) cascade, and accurately reflects KRAS- and ERK-regulated gene transcription in KRAS-mutant cancer patients. Integration with our ERK-regulated phospho- and total proteome highlights ERK deregulation of the anaphase promoting complex/cyclosome (APC/C) and other components of the cell cycle machinery as key processes that drive pancreatic ductal adenocarcinoma (PDAC) growth. Our findings elucidate mechanistically the critical role of ERK in driving KRAS-mutant tumor growth and in resistance to KRAS-ERK MAPK targeted therapies.

Small GTPase control of pituitary hormone secretion: Evidence from studies in the goldfish (Carassius auratus) neuroendocrine model

The secretion of vertebrate pituitary hormones is regulated by multiple hypothalamic factors, which, while generally activating unique receptor systems, ultimately propagate signals through interacting intracellular regulatory elements to modulate hormone exocytosis. One important family of intracellular regulators is the monomeric small GTPases, a subset of which (Arf1/6, Rac, RhoA, and Ras) is highly conserved across vertebrates and regulates secretory vesicle exocytosis in many cell types. In this study, we investigated the roles of these small GTPases in basal and agonist-dependent hormone release from dispersed goldfish (Carassius auratus) pituitary cells in perifusion experiments. Inhibition of these small GTPases elevated basal LH and GH secretion, except for Ras inhibition which only increased basal LH release. However, variable responses were observed with regard to LH and GH responses to the two goldfish native gonadotropin-releasing hormones (GnRH2 and GnRH3). GnRH-dependent LH release, but not GH secretion, was mediated by Arf1/6 GTPases. In contrast, inhibition of Rac and RhoA GTPases selectively enhanced GnRH3- and GnRH2-dependent GH release, respectively, while Ras inhibition only enhanced GnRH3-evoked LH secretion. Together, our results reveal novel divergent cell-type- and ligand-specific roles for small GTPases in the control of goldfish pituitary hormone exocytosis in unstimulated and GnRH-evoked release.

The application of pancreatic cancer organoids for novel drug discovery

INTRODUCTION

Pancreatic ductal adenocarcinoma presents with a dismal prognosis. Personalized therapy is urgently warranted to overcome the treatment limitations of the "one-size-fits-all" scheme. Organoids have emerged as fundamental novel tools to study tumor biology and heterogeneity, hence overcoming limitations of other model systems by better-reflecting tissue heterogeneity and recapitulating in-vivo processes. Besides their crucial role in basic research, they have evolved as tools for translational drug discovery and patient stratification.

AREAS COVERED

This review highlights the achievements of an organoid-based drug investigation and discovery. The authors present an overview of studies using organoids for drug testing. Further, they pinpoint studies correlating the in vitro prediction of organoids to the actual patient`s response. Furthermore, the authors describe novel model systems and take a thorough overlook of microfluidic chips, synthetic matrices, multicellular systems, bioprinting, and stem cell-derived pancreatic organoid systems.

EXPERT OPINION

Organoid systems promise great potential for future clinical applications. Indeed, they may be implemented into informed decision-making for guiding therapies. However, validation by randomized trials is mandatory. Additionally, organoids in combination with other cellular compartments may be exploited for drug discovery by studying niche-tumor interaction. Yet, several precautions must be kept in mind, such as standardization and reproducibility.

Targeting the 'Undruggable' Driver Protein, KRAS, in Epithelial Cancers: Current Perspective

This review summarizes recent development in synthetic drugs and biologics targeting intracellular driver genes in epithelial cancers, focusing on KRAS, and provides a current perspective and potential leads for the field. Compared to biologics, small molecule inhibitors (SMIs) readily penetrate cells, thus being able to target intracellular proteins. However, SMIs frequently suffer from pleiotropic effects, off-target cytotoxicity and invariably elicit resistance. In contrast, biologics are much larger molecules limited by cellular entry, but if this is surmounted, they may have more specific effects and less therapy-induced resistance. Exciting breakthroughs in the past two years include engineering of non-covalent KRAS G12D-specific inhibitor, probody bispecific antibodies, drug-peptide conjugate as MHC-restricted neoantigen to prompt immune response by T-cells, and success in the adoptive cell therapy front in both breast and pancreatic cancers.

Computer-Aided Drug Design Boosts RAS Inhibitor Discovery

The Rat Sarcoma (RAS) family (NRAS, HRAS, and KRAS) is endowed with GTPase activity to regulate various signaling pathways in ubiquitous animal cells. As proto-oncogenes, RAS mutations can maintain activation, leading to the growth and proliferation of abnormal cells and the development of a variety of human cancers. For the fight against tumors, the discovery of RAS-targeted drugs is of high significance. On the one hand, the structural properties of the RAS protein make it difficult to find inhibitors specifically targeted to it. On the other hand, targeting other molecules in the RAS signaling pathway often leads to severe tissue toxicities due to the lack of disease specificity. However, computer-aided drug design (CADD) can help solve the above problems. As an interdisciplinary approach that combines computational biology with medicinal chemistry, CADD has brought a variety of advances and numerous benefits to drug design, such as the rapid identification of new targets and discovery of new drugs. Based on an overview of RAS features and the history of inhibitor discovery, this review provides insight into the application of mainstream CADD methods to RAS drug design.

Mechanistic insights into the clinical Y96D mutation with acquired resistance to AMG510 in the KRASG12C

Special oncogenic mutations in the RAS proteins lead to the aberrant activation of RAS and its downstream signaling pathways. AMG510, the first approval drug for KRAS, covalently binds to the mutated cysteine 12 of KRASG12C protein and has shown promising antitumor activity in clinical trials. Recent studies have reported that the clinically acquired Y96D mutation could severely affect the effectiveness of AMG510. However, the underlying mechanism of the drug-resistance remains unclear. To address this, we performed multiple microsecond molecular dynamics simulations on the KRASG12C−AMG510 and KRASG12C/Y96D−AMG510 complexes at the atomic level. The direct interaction between the residue 96 and AMG510 was impaired owing to the Y96D mutation. Moreover, the mutation yielded higher flexibility and more coupled motion of the switch II and α3-helix, which led to the departing motion of the switch II and α3-helix. The resulting departing motion impaired the interaction between the switch II and α3-helix and subsequently induced the opening and loosening of the AMG510 binding pocket, which further disrupted the interaction between the key residues in the pocket and AMG510 and induced an increased solvent exposure of AMG510. These findings reveal the resistance mechanism of AMG510 to KRASG12C/Y96D, which will help to offer guidance for the development of KRAS targeted drugs to overcome acquired resistance.