Small-molecule inhibition of MAP2K4 is synergistic with RAS inhibitors in KRAS-mutant cancers

Targeting KRASG12C Mutation: Development of effective strategies to overcome drug resistance and limited efficacy

The KRASG12C mutation causes the KRAS protein to remain in a constantly activated state, thereby promoting cell proliferation and cancer progression. As researchers have transitioned the KRASG12C mutation from being "undruggable" to "druggable", the development of KRASG12C inhibitors has reached a peak. However, some KRASG12C inhibitors have shown resistance in preclinical studies and clinical trials, resulting in poor clinical outcomes and limiting their application. This review summarizes emerging strategies to overcome resistance, including optimization strategies for KRASG12C mutation site inhibitors (including covalent inhibitors and degraders), as well as potential therapeutic strategies involving combination therapies and multi-target inhibition targeting major resistance mechanisms. Additionally, it discusses the potential issues and challenges that may arise in the development of treatments for KRASG12C mutation resistance. It is hoped that this review can provide insightful perspectives to help overcome KRASG12C inhibitor resistance.

Spike-in enhanced phosphoproteomics uncovers synergistic signaling responses to MEK inhibition in colon cancer cells

Targeted kinase inhibitors are a cornerstone of cancer therapy, but their success is often hindered by the complexity of cellular signaling networks that can lead to resistance. Overcoming this challenge necessitates a deep understanding of cellular signaling responses. While standard global phosphoproteomics offers extensive insights, lengthy processing times, the complexity of data interpretation, and frequent omission of crucial phosphorylation sites limit its utility. Here, we combine data-independent acquisition (DIA) with spike-in of synthetic heavy stable isotope-labeled phosphopeptides to facilitate the targeted detection of particularly informative phosphorylation sites. Our spike-in enhanced detection in DIA (SPIED-DIA) approach integrates the improved sensitivity of spike-in-based targeted detection with the discovery potential of global phosphoproteomics into a simple workflow. We employed this method to investigate synergistic signaling responses in colorectal cancer cell lines following MEK inhibition. Our findings highlight that combining MEK inhibition with growth factor stimulation synergistically activates JNK signaling in HCT116 cells. This synergy emphasizes the therapeutic potential of concurrently targeting MEK and JNK pathways, as evidenced by the significantly impaired growth of HCT116 cells when treated with both inhibitors. Our results demonstrate that SPIED-DIA effectively identifies synergistic signaling responses in colorectal cancer cells, presenting a valuable tool for uncovering new therapeutic targets and strategies in cancer treatment.

Drugging the Undruggable and beyond: Emerging precision oncology approaches to target acquired resistance to KRAS G12C and KRAS G12D inhibitors

Development of mutant specific KRAS inhibitors validated KRAS as a 'druggable' target. However, excellent initial efficacy was eventually overshadowed by failure to exhibit sustained clinical response, primarily due to acquired resistance. Some targeted therapies like SOS1, SHP2, and MEK inhibitors, in combination with mutant KRAS G12C inhibitors (G12Ci), are currently under clinical investigation with evidences of improving efficacy. However, a deep understanding of the underlying molecular pathways behind the acquired resistance is still at a nascent stage. Recent preclinical studies have uncovered a role of novel proteins and pathways responsible for resistance and their inhibition demonstrated a robust anticancer efficacy in combination. Plethora of combination therapy approaches are now being proposed with emergence of AXL, ULK1, Tissue factor, farnesyltransferase, etc. as targets to counter G12Ci resistance. This review summarizes in a comprehensive manner, some of the novel combination modalities to overcome G12Ci resistance, based on current understanding and with great potential to hit clinical success. Along with G12C, KRAS G12D (G12D) was also considered a formidable foe, until the discovery of selective inhibitors. However, eventual clinical resistance can eclipse the early success and requires an in-depth understanding of resistance mechanisms. Evidences of G12Ci resistance can be exploited as probable combination strategies to tackle ensuing resistance to G12D inhibitors (G12Di), and can translate in superior clinical efficacy. Early preclinical studies of G12Di in combination with ERBB, SOS1, AKT and immune-checkpoints inhibitors indicate encouraging response. This review further describes some of the early affirmations on combination strategies with G12Di. We postulate to go beyond 'Drugging the Undruggable' with advanced combination approaches mitigating G12C and G12D inhibitor resistance.

Deciphering the endogenous SUMO-1 landscape: a novel combinatorial peptide enrichment strategy for global profiling and disease association

Small ubiquitin-like modifier (SUMO) plays a pivotal role in diverse cellular processes and is implicated in diseases such as cancer and neurodegenerative disorders. However, large-scale identification of endogenous SUMO-1 faces challenges due to limited enrichment methods and its lower abundance compared to SUMO-2/3. Here we propose a novel combinatorial peptide strategy, combined with anti-adhesive polymer development, to enrich endogenous SUMO-1 modified peptides, revealing a comprehensive SUMOylation landscape. Utilizing phage display, we successfully identified a linear 12-mer and a cystine-linked cyclic 7-mer peptide ligand, specifically designed to target the C-terminal regions of SUMO-1 remnants. Building upon their high affinities and satisfactory complementarity, we developed the first artificial SUMO-1 enrichment materials, ultimately establishing a combinatorial peptide strategy that facilitates a comprehensive analysis of the endogenous SUMO-1 modified proteome in both cellular and tissue contexts. We successfully mapped 1312 SUMOylation sites in HeLa cells and 1365 along with 991 endogenous SUMOylation proteins in Alzheimer's disease (AD) mouse brain tissues. Notably, our method uncovered a significant upregulation of SUMO-1 in AD mouse brain tissue, providing new insights into SUMOylation's role in disease. Overall, this work represents the most thorough exploration of SUMO-1 modified proteomics and offers robust tools for elucidating the roles of SUMO-1's biological significance.

Synthetic lethal strategies for the development of cancer therapeutics

Synthetic lethality is a genetic phenomenon whereby the simultaneous presence of two different genetic alterations impairs cellular viability. Importantly, targeting synthetic lethal interactions offers potential therapeutic strategies for cancers with alterations in pathways that might otherwise be considered undruggable. High-throughput screening methods based on modern CRISPR-Cas9 technologies have emerged and become crucial for identifying novel synthetic lethal interactions with the potential for translation into biologically rational cancer therapeutic strategies as well as associated predictive biomarkers of response capable of guiding patient selection. Spurred by the clinical success of PARP inhibitors in patients with BRCA-mutant cancers, novel agents targeting multiple synthetic lethal interactions within DNA damage response pathways are in clinical development, and rational strategies targeting synthetic lethal interactions spanning alterations in epigenetic, metabolic and proliferative pathways have also emerged and are in late preclinical and/or early clinical testing. In this Review, we provide a comprehensive overview of established and emerging technologies for synthetic lethal drug discovery and development and discuss promising therapeutic strategies targeting such interactions.

KRAS-mutant non-small cell lung cancer (NSCLC) therapy based on tepotinib and omeprazole combination

BACKGROUND

KRAS-mutant non-small cell lung cancer (NSCLC) shows a relatively low response rate to chemotherapy, immunotherapy and KRAS-G12C selective inhibitors, leading to short median progression-free survival, and overall survival. The MET receptor tyrosine kinase (c-MET), the cognate receptor of hepatocyte growth factor (HGF), was reported to be overexpressed in KRAS-mutant lung cancer cells leading to tumor-growth in anchorage-independent conditions.

METHODS

Cell viability assay and synergy analysis were carried out in native, sotorasib and trametinib-resistant KRAS-mutant NSCLC cell lines. Colony formation assays and Western blot analysis were also performed. RNA isolation from tumors of KRAS-mutant NSCLC patients was performed and KRAS and MET mRNA expression was determined by real-time RT-qPCR. In vivo studies were conducted in NSCLC (NCI-H358) cell-derived tumor xenograft model.

RESULTS

Our research has shown promising activity of omeprazole, a V-ATPase-driven proton pump inhibitor with potential anti-cancer properties, in combination with the MET inhibitor tepotinib in KRAS-mutant G12C and non-G12C NSCLC cell lines, as well as in G12C inhibitor (AMG510, sotorasib) and MEK inhibitor (trametinib)-resistant cell lines. Moreover, in a xenograft mouse model, combination of omeprazole plus tepotinib caused tumor growth regression. We observed that the combination of these two drugs downregulates phosphorylation of the glycolytic enzyme enolase 1 (ENO1) and the low-density lipoprotein receptor-related protein (LRP) 5/6 in the H358 KRAS G12C cell line, but not in the H358 sotorasib resistant, indicating that the effect of the combination could be independent of ENO1. In addition, we examined the probability of recurrence-free survival and overall survival in 40 early lung adenocarcinoma patients with KRAS G12C mutation stratified by KRAS and MET mRNA levels. Significant differences were observed in recurrence-free survival according to high levels of KRAS mRNA expression. Hazard ratio (HR) of recurrence-free survival was 7.291 (p = 0.014) for high levels of KRAS mRNA expression and 3.742 (p = 0.052) for high MET mRNA expression.

CONCLUSIONS

We posit that the combination of the V-ATPase inhibitor omeprazole plus tepotinib warrants further assessment in KRAS-mutant G12C and non G12C cell lines, including those resistant to the covalent KRAS G12C inhibitors.