Precision medicine for pancreatic cancer: Characterizing the clinico-genomic landscape and outcomes of KRAS G12C-mutated disease

BACKGROUND

Mutated KRAS is the most common oncogene alteration in pancreatic cancer (PDAC), and KRAS G12C mutations (KRAS G12Cmut) are observed in 1-2%. Several inhibitors of KRAS G12C have recently demonstrated promise in solid tumors, including PDAC. Little is known regarding clinical, genomics and outcome data of this population.

METHODS

Patients with PDAC and KRAS G12Cmut were identified at Memorial Sloan Kettering Cancer Center (MSK), and via the AACR Project GENIE database. Clinical, treatment, genomic and outcomes data were analysed. A cohort of patients at MSK with non-G12C KRAS PDAC was included for comparison.

RESULTS

Among 3,571 patients with PDAC, 39 with KRAS G12Cmut were identified (1.1%). Median age was 67 years, 56% were female. Median BMI was 29.2 kg/m2, 67% had a smoking history. Median OS 13 months (9.4, not reached (NR)) for stage IV, and 26 months (23, NR) for stage I-III. Complete genomic data (via AACR GENIE) was available for N = 74. Most common co-alterations included: TP53 (73%), CDKN2A (33%), SMAD4 (28%), and ARID1A (21%). Compared with a large cohort (N = 2931) of non-G12C KRAS-mutated PDAC, ARID1A co-mutations were more frequent in KRAS G12Cmut (P < .05). OS did not differ between KRAS G12Cmut and non-G12C KRAS PDAC. Germline pathogenic variants were identified in 17%. N = 2 received KRAS G12C-directed therapy.

CONCLUSION

PDAC and KRAS G12Cmut may be associated with a distinct clinical phenotype. Genomic features are similar to non-G12C KRAS-mutated PDAC, although enrichment of ARID1A co-mutations was observed. Targeting of KRAS G12C in PDAC provides a precedent for broader KRAS targeting in PDAC.

Targeting KRASG12C in Non-Small-Cell Lung Cancer: Current Standards and Developments

Among the most common molecular alterations detected in non-small-cell lung cancer (NSCLC) are mutations in Kristen Rat Sarcoma viral oncogene homolog (KRAS). KRAS mutant NSCLC is a heterogenous group of diseases, different from other oncogene-driven tumors in terms of biology and response to therapies. Despite efforts to develop drugs aimed at inhibiting KRAS or its signaling pathways, KRAS had remained undruggable for decades. The discovery of a small pocket in the binding switch II region of KRASG12C has revolutionized the treatment of KRASG12C-mutated NSCLC patients. Sotorasib and adagrasib, direct KRASG12C inhibitors, have been approved by the US Food and Drug Administration (FDA) and other regulatory agencies for patients with previously treated KRASG12C-mutated NSCLC, and these advances have become practice changing. However, first-line treatment in KRASG12C-mutated NSCLC does not differ from NSCLC without actionable driver genomic alterations. Treatment with KRASG12C inhibitors is not curative and patients develop progressive disease, so understanding associated mechanisms of drug resistance is key. New KRASG12C inhibitors and several combination therapy strategies, including with immune checkpoint inhibitors, are being studied in clinical trials. The aim of this review is to explore the clinical impact of KRAS, and outline different treatment approaches, focusing on the novel treatment of KRASG12C-mutated NSCLC.

Molecular Landscape and Therapeutic Strategies against Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer deaths worldwide. Although the overall incidence of CRC is decreasing, the incidence of young-onset CRC, characterized by a diagnosis of CRC before age 50, is increasing. Outcomes for CRC patients are improving, partly due to comprehensive molecular characterization of tumors and novel therapeutic strategies. Advances in genomic and transcriptomic analyses using blood- and tumor-tissue-based sequencing have facilitated identification of distinct tumor subtypes harboring unique biological characteristics and therapeutic vulnerabilities. These insights have led to the development and incorporation of targeted therapies and immunotherapy in CRC treatment. In this review, we discuss the molecular landscape and key oncogenes/tumor suppressors contributing to CRC tumorigenesis, metastasis, and therapeutic resistance. We also discuss personalized therapeutic strategies for subsets of CRC patients and provide an overview of evolving novel treatments being evaluated in clinical trials.

From bench to bedside: current development and emerging trend of KRAS-targeted therapy

Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) is the most frequently mutated oncogene in human cancers with mutations predominantly occurring in codon 12. These mutations disrupt the normal function of KRAS by interfering with GTP hydrolysis and nucleotide exchange activity, making it prone to the GTP-bound active state, thus leading to sustained activation of downstream pathways. Despite decades of research, there has been no progress in the KRAS drug discovery until the groundbreaking discovery of covalently targeting the KRASG12C mutation in 2013, which led to revolutionary changes in KRAS-targeted therapy. So far, two small molecule inhibitors sotorasib and adagrasib targeting KRASG12C have received accelerated approval for the treatment of non-small cell lung cancer (NSCLC) harboring KRASG12C mutations. In recent years, rapid progress has been achieved in the KRAS-targeted therapy field, especially the exploration of KRASG12C covalent inhibitors in other KRASG12C-positive malignancies, novel KRAS inhibitors beyond KRASG12C mutation or pan-KRAS inhibitors, and approaches to indirectly targeting KRAS. In this review, we provide a comprehensive overview of the molecular and mutational characteristics of KRAS and summarize the development and current status of covalent inhibitors targeting the KRASG12C mutation. We also discuss emerging promising KRAS-targeted therapeutic strategies, with a focus on mutation-specific and direct pan-KRAS inhibitors and indirect KRAS inhibitors through targeting the RAS activation-associated proteins Src homology-2 domain-containing phosphatase 2 (SHP2) and son of sevenless homolog 1 (SOS1), and shed light on current challenges and opportunities for drug discovery in this field.

Abnormalities in the KRAS Gene and Treatment Options for NSCLC Patients with the G12C Mutation in This Gene-A Literature Review and Single-Center Experience

Mutations in the KRAS gene are among the most common mutations observed in cancer cells, but they have only recently become an achievable goal for targeted therapies. Two KRAS inhibitors, sotorasib and adagrasib, have recently been approved for the treatment of patients with advanced non-small cell lung cancer with the KRAS G12C mutation, while studies on their efficacy are still ongoing. In this work, we comprehensively analyzed RAS gene mutations' molecular background, mutation testing, KRAS inhibitors' effectiveness with an emphasis on non-small cell lung cancer, the impact of KRAS mutations on immunotherapy outcomes, and drug resistance problems. We also summarized ongoing trials and analyzed emerging perspectives on targeting KRAS in cancer patients.

Targeting KRAS-Mutated Gastrointestinal Malignancies with Small-Molecule Inhibitors: A New Generation of Breakthrough Therapies

Kirsten rat sarcoma virus (KRAS) is one of the most important and frequently mutated oncogenes in cancer and the mutational prevalence is especially high in many gastrointestinal malignancies, including colorectal cancer and pancreatic ductal adenocarcinoma. The KRAS protein is a small GTPase that functions as an "on/off" switch to activate downstream signaling, mainly through the mitogen-activated protein kinase pathway. KRAS was previously considered undruggable because of biochemical constraints; however, recent breakthroughs have enabled the development of small-molecule inhibitors of KRAS G12C. These drugs were initially approved in lung cancer and have now shown substantial clinical activity in KRAS G12C-mutated pancreatic ductal adenocarcinoma as well as colorectal cancer when combined with anti-EGFR monoclonal antibodies. Early data are encouraging for other gastrointestinal cancers as well and many other combination strategies are being investigated. Several new KRAS G12C inhibitors and novel inhibitors of other KRAS alterations have recently entered the clinic. These molecules employ a variety of innovative mechanisms and have generated intense interest. These novel drugs are especially important as KRAS G12C is rare in gastrointestinal malignancies compared with other KRAS alterations, representing potentially groundbreaking advances. Soon, the rapidly evolving landscape of novel KRAS inhibitors may substantially shift the therapeutic landscape for gastrointestinal cancers and offer meaningful survival improvements.

Optimizing the first-line treatment for metastatic colorectal cancer

Colorectal cancer represents an important oncological challenge both for its incidence, which makes it an important health problem, and for its biological complexity, which has made clinical results very difficult in terms of outcome for this category of patients. To date these diseases should not be treated as a single entity but it is necessary to distinguish colorectal cancers based on characteristics that nowadays are essential to have greater therapeutic benefits. These include the sideness of the disease, the state of microsatellites, the presence of prognostic and predictive mutations of response to treatments currently available in clinical practice, which are associated with new therapeutic targets. The greatest challenge in the future will be to circumvent the resistance mechanisms that make this disease very difficult to treat with good long-term results by studying effective combination treatments with a good toxicity profile. Once such combinations or targeted treatments are consolidated, it will be desirable to shift the best therapies to the first line treatment to make them immediately accessible to the patient. It will also be essential to refine the selection of patients who can benefit from these treatments.

Germline variation in RASAL2 may predict survival in patients with RAS-activated colorectal cancer

BACKGROUND

Therapeutic agents that specifically target patients with RAS mutant colorectal cancer (CRC) are needed. We sought potential drug targets by relating genome-wide association study and survival data in patients with advanced CRC profiled for mitogen-activated protein kinase (MAPK) pathway mutations.

METHODS

In total, 694 patients from the clinical trials COIN and COIN-B had MAPK-activated CRCs (assigned as KRAS, NRAS, or BRAF mutant). Genome-wide single nucleotide polymorphism (SNP), gene, and gene-set analyses were performed to identify determinants of survival. For rs12028023 in RAS protein activator-like 2 (RASAL2), we studied its effect by MAPK pathway activation status (by comparing to 760 patients without MAPK-activated CRCs), MAPK gene mutation status, surface area of the primary tumor (as a marker of proliferation), and expression on RASAL2.

RESULTS

In MAGMA genome-wide analyses, RASAL2 was the most significant gene associated with survival (p = 2.0 × 10-5 ). Patients carrying the minor (A) allele in the lead SNP, rs12028023 in intron 1 of RASAL2, had a median increase in survival of 167 days as compared with patients carrying the major allele. rs12028023 was predictive for survival by MAPK-activation status (pZ-test  = 2.1 × 10-3 ). Furthermore, rs12028023 improved survival in patients with RAS mutant (hazard ratio [HR] = 0.62, 95% confidence intervals [CI] = 0.5-0.8, p = 3.4 × 10-5 ) but not BRAF mutant (p = 0.87) CRCs. The rs12028023 A-allele was associated with reduced surface area of the primary tumor (Beta = -0.037, standard error [SE] = 0.017, p = 3.2 × 10-2 ) and reduced RASAL2 expression in cultured fibroblasts (p = 1.6 × 10-11 ).

CONCLUSION

Our data demonstrate a prognostic role for RASAL2 in patients with MAPK-activated CRCs, with potential as a therapeutic target.

Adagrasib: a novel inhibitor for KRASG12C-mutated non-small-cell lung cancer

Adagrasib is a recently US FDA-approved novel KRAS^G12C targeted therapy with clinical efficacy in patients with advanced, pretreated KRAS^G12C-mutated non-small-cell lung cancer. KRYSTAL-I reported an objective response rate of 42.9% with median duration of response of 8.5 months. Treatment-related adverse events were primarily gastrointestinal and occurred in 97.4% of patients, with grade 3+ treatment-related adverse events occurring in 44.8% of patients. This review details the preclinical and clinical data for adagrasib in the treatment of non-small-cell lung cancer. We also outline practical clinical administration guidelines for this novel therapy, including management of toxicities. Finally, we discuss the implications of resistance mechanisms, summarize other KRAS^G12C inhibitors currently in development and outline future directions for adagrasib-based combination therapies.

Selenite as a dual apoptotic and ferroptotic agent synergizes with EGFR and KRAS inhibitors with epigenetic interference

BACKGROUND

Selenium, an essential trace element, has previously been investigated as a pro-apoptotic and DNA demethylation agent. It sensitizes the response to chemotherapy in patients who were refractory to cytotoxic agents. Meanwhile, ferroptosis is a novel approach to cancer treatment by triggering cell death and reversing drug resistance. The role of selenium in treating cancer cells harboring druggable oncogenic alterations and its underlying mechanism are largely unknown.

RESULTS

We treated lung adenocarcinoma cell lines-EGFR-mutant H1975 (H1975 ^{EGFR p.L858R and p.T790M}) and KRAS-mutant H358 (H358 ^{KRAS p.G12C}), with sodium selenite to examine its effect on cell apoptosis, ferroptosis, and DNA methylation, as well as its interaction with existing targeted therapy, osimertinib, and adagrasib. We observed selenite to be a dual apoptotic and ferroptotic agent on lung cancer cells, associated with the activation of p38-ATF4-DDIT3 axis in the unfolded protein response. Ferroptosis induction was more remarkable in H1975 than H358. Selenite also altered cellular DNA methylation machinery through downregulating DNMT1 and upregulating TET1, though not as a major mechanism of its activity. Low-dose selenite synergized with osimertinib in EGFR-mutant H1975, and with adagrasib in KRAS-mutant H358, with stronger synergism observed in H1975.

CONCLUSION

These results suggest that selenite is a potential apoptotic and ferroptotic drug candidate for the treatment of especially EGFR- and potentially KRAS-mutant lung cancer.

Adagrasib: First Approval

Adagrasib (KRAZATI™) is an orally available, potent, irreversible, small molecule inhibitor of KRAS G12C mutant isoform being developed by Mirati Therapeutics for the treatment of solid tumours harbouring KRAS G12C oncogenic driver mutation, including non-small cell lung cancer (NSCLC) and colorectal cancer (CRC). Adagrasib covalently binds to the mutant cysteine in KRAS G12C and locks the mutant KRAS protein in its inactive state, thereby preventing downstream signalling without affecting wild-type KRAS protein. In December 2022, adagrasib received its first approval in the USA for the treatment of adults with KRAS G12C-mutated locally advanced or metastatic NSCLC (as determined by an FDA approved test) who have received ≥ 1 prior systemic therapy. It was approved under accelerated approval based on objective response rate and duration of response, and its continued approval for this indication may be contingent upon verification and description of a clinical benefit in a confirmatory trial(s). The drug is under regulatory review for NSCLC in the European Union and is in development for CRC in the US. Clinical studies of adagrasib in solid tumours, including CRC, are underway in several countries. This article summarizes the milestones in the development of adagrasib leading to this first approval for KRAS G12C-mutated locally advanced or metastatic NSCLC.

Integrated Decision-Making in the Treatment of Colon-Rectal Cancer: The Case of KRAS-Mutated Tumors

In recent years, precision medicine has taken an increasing place in various branches of medical oncology, including colorectal cancer. Among the potentially relevant mutations for this cancer is the KRAS mutation, initially defined as "untargetable"; today, we see the birth of new molecules that target one of the variants of the KRAS mutation, KRAS G12C, having a significant impact on the therapeutic options for other malignancies, such as metastatic lung cancer. This fundamental step forward has stimulated scientific research on other potential targets of KRAS, both indirect and direct, and combination treatments aiming to overcome the mechanisms of resistance to these drugs that decrease in efficacy in colorectal cancer. What was once a negative predictive marker of response to anti-EGFR drugs today has become a potential target for targeted treatments. In turn, the prognostic role of the mutation has become extremely interesting, making it a potentially useful element in therapeutic decision-making, not only regarding oncological treatments but also in a more complex and complete manner within a global vision of the patient, involving other figures on the multidisciplinary team, such as surgeons, radiotherapists, and interventional radiologists.

Combined KRASG12C and SOS1 inhibition enhances and extends the anti-tumor response in KRASG12C-driven cancers by addressing intrinsic and acquired resistance

Efforts to improve the anti-tumor response to KRASG12C targeted therapy have benefited from leveraging combination approaches. Here, we compare the anti-tumor response induced by the SOS1-KRAS interaction inhibitor, BI-3406, combined with a KRASG12C inhibitor (KRASG12Ci) to those induced by KRASG12Ci alone or combined with SHP2 or EGFR inhibitors. In lung cancer and colorectal cancer (CRC) models, BI-3406 plus KRASG12Ci induces an anti-tumor response stronger than that observed with KRASG12Ci alone and comparable to those by the other combinations. This enhanced anti-tumor response is associated with a stronger and extended suppression of RAS-MAPK signaling. Importantly, BI-3406 plus KRASG12Ci treatment delays the emergence of acquired adagrasib resistance in both CRC and lung cancer models and is associated with re-establishment of anti-proliferative activity in KRASG12Ci-resistant CRC models. Our findings position KRASG12C plus SOS1 inhibition therapy as a promising strategy for treating both KRASG12C-mutated tumors as well as for addressing acquired resistance to KRASG12Ci.

CodeBreak 200: Sotorasib Has Not Broken the KRASG12C Enigma Code

Thirteen percent of non-small cell lung cancer (NSCLC) patients are estimated to have the KRAS G12C mutation. Sotorasib is a novel KRAS G12C inhibitor that has shown promising results in preclinical and clinical studies, granting its conditional approval by the FDA in May 2021. The phase I clinical trial resulted in a confirmed response of 32% and progression free survival (PFS) of 6.3 months while the phase II trial resulted in a confirmed response of 37.1% and a PFS of 6.8 months. It was also shown to be tolerable with most subjects experiencing grade one or two adverse events, most commonly diarrhea and nausea. The CodeBreaK 200 phase III trial data have recently resulted and showed an improved PFS with the use of sotorasib at 5.6 months compared to that of standard docetaxel of 4.5 months in locally advanced or unresectable metastatic KRAS G12C NSCLC previously treated with at least one platinum-based chemotherapy and checkpoint inhibitor. The lower than expected PFS of sotorasib from the phase III trial opens up opportunities for other G12C inhibitors to join the field. Indeed, adagrasib, another G12C inhibitor just recently gained FDA accelerated approval in NSCLC patients based on the KRYSTAL-1 study where the response rate was 43% with a median duration of response of 8.5 months. With novel agents and combinations, the field of KRAS G12C is quickly evolving. While sotorasib was an exciting start, there is more to do to break the KRAS G12C Enigma code.

Design of new drugs for medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is one of the common malignant endocrine tumors, which seriously affects human health. Although surgical resection offers a potentially curative therapeutic option to some MTC patients, most patients do not benefit from it due to the difficulty to access the tumors and tumor metastasis. The survival rate of MTC patients has improved with the recent advances in the research, which has improved our understanding of the molecular mechanism underlying MTC and enabled the development and approval of novel targeted drugs. In this article, we reviewed the molecular mechanisms related to MTC progression and the principle for the design of molecular targeted drugs, and proposed some future directions for prospective studies exploring targeted drugs for MTC.

The current state of the art and future trends in RAS-targeted cancer therapies

Despite being the most frequently altered oncogenic protein in solid tumours, KRAS has historically been considered ‘undruggable’ owing to a lack of pharmacologically targetable pockets within the mutant isoforms. However, improvements in drug design have culminated in the development of inhibitors that are selective for mutant KRAS in its active or inactive state. Some of these inhibitors have proven efficacy in patients with KRAS^G12C-mutant cancers and have become practice changing. The excitement associated with these advances has been tempered by drug resistance, which limits the depth and/or duration of responses to these agents. Improvements in our understanding of RAS signalling in cancer cells and in the tumour microenvironment suggest the potential for several novel combination therapies, which are now being explored in clinical trials. Herein, we provide an overview of the RAS pathway and review the development and current status of therapeutic strategies for targeting oncogenic RAS, as well as their potential to improve outcomes in patients with RAS-mutant malignancies. We then discuss challenges presented by resistance mechanisms and strategies by which they could potentially be overcome.

The RAS oncogenes are among the most common drivers of tumour development and progression but have historically been considered undruggable. The development of direct KRAS inhibitors has changed this paradigm, although currently clinical use of these novel therapeutics is limited to a select subset of patients, and intrinsic or acquired resistance presents an inevitable challenge to cure. Herein, the authors provide an overview of the RAS pathway in cancer and review the ongoing efforts to develop effective therapeutic strategies for RAS-mutant cancers. They also discuss the current understanding of mechanisms of resistance to direct KRAS inhibitors and strategies by which they might be overcome.

Owing to intrinsic and extrinsic factors, KRAS and other RAS isoforms have until recently been impervious to targeting with small-molecule inhibitors.

Inhibitors of the KRAS^G12C variant constitute a potential breakthrough in the treatment of many cancer types, particularly non-small-cell lung cancer, for which such an agent has been approved by the FDA.

Several forms of resistance to KRAS inhibitors have been defined, including primary, adaptive and acquired resistance; these resistance mechanisms are being targeted in studies that combine KRAS inhibitors with inhibitors of horizontal or vertical signalling pathways.

Mutant KRAS has important effects on the tumour microenvironment, including the immunological milieu; these effects must be considered to fully understand resistance to KRAS inhibitors and when designing novel treatment strategies.

Molecular Biology and Therapeutic Perspectives for K-Ras Mutant Non-Small Cell Lung Cancers

In non-small cell lung cancer (NSCLC) the most common alterations are identified in the Kirsten rat sarcoma viral oncogene homolog (KRAS) gene, accounting for approximately 30% of cases in Caucasian patients. The majority of mutations are located in exon 2, with the c.34G > T (p.G12C) change being the most prevalent. The clinical relevance of KRAS mutations in NSCLC was not recognized until a few years ago. What is now emerging is a dual key role played by KRAS mutations in the management of NSCLC patients. First, recent data report that KRAS-mutant lung AC patients generally have poorer overall survival (OS). Second, a KRAS inhibitor specifically targeting the c.34G > T (p.G12C) variant, Sotorasib, has been approved by the U.S. Food and Drug Administration (FDA) and by the European Medicines Agency. Another KRAS inhibitor targeting c.34G > T (p.G12C), Adagrasib, is currently being reviewed by the FDA for accelerated approval. From the description of the biology of KRAS-mutant NSCLC, the present review will focus on the clinical aspects of KRAS mutations in NSCLC, in particular on the emerging efficacy data of Sotorasib and other KRAS inhibitors, including mechanisms of resistance. Finally, the interaction between KRAS mutations and immune checkpoint inhibitors will be discussed.

Efficacy of Combined Use of Everolimus and Second-Generation Pan-EGRF Inhibitors in KRAS Mutant Non-Small Cell Lung Cancer Cell Lines

Background: EGFR mutations are present in approximately 15−50% of non-small cell lung cancer (NSCLC), which are predictive of anti-EGFR therapies. At variance, NSCLC patients harboring KRAS mutations are resistant to those anti-EGFR approaches. Afatinib and allitinib are second-generation pan-EGFR drugs, yet no predictive biomarkers are known in the NSCLC context. In the present study, we evaluated the efficacy of pan-EGFR inhibitors in a panel of 15 lung cancer cell lines associated with the KRAS mutations phenotype. Methods: KRAS wild-type sensitive NCI-H292 cell line was further transfected with KRAS mutations (p.G12D and p.G12S). The pan-EGFR inhibitors’ activity and biologic effect of KRAS mutations were evaluated by cytotoxicity, MAPK phospho-protein array, colony formation, migration, invasion, and adhesion. In addition, in vivo chicken chorioallantoic membrane assay was performed in KRAS mutant cell lines. The gene expression profile was evaluated by NanoString. Lastly, everolimus and pan-EGFR combinations were performed to determine the combination index. Results: The GI50 score classified two cell lines treated with afatinib and seven treated with allitinib as high-sensitive phenotypes. All KRAS mutant cell lines demonstrated a resistant profile for both therapies (GI50 < 30%). The protein array of KRAS edited cells indicated a significant increase in AKT, CREB, HSP27, JNK, and, importantly, mTOR protein levels compared with KRAS wild-type cells. The colony formation, migration, invasion, adhesion, tumor perimeter, and mesenchymal phenotype were increased in the H292 KRAS mutated cells. Gene expression analysis showed 18 dysregulated genes associated with the focal adhesion-PI3K-Akt-mTOR-signaling correlated in KRAS mutant cell lines. Moreover, mTOR overexpression in KRAS mutant H292 cells was inhibited after everolimus exposure, and sensitivity to afatinib and allitinib was restored. Conclusions: Our results indicate that allitinib was more effective than afatinib in NSCLC cell lines. KRAS mutations increased aggressive behavior through upregulation of the focal adhesion-PI3K-Akt-mTOR-signaling in NSCLC cells. Significantly, everolimus restored sensibility and improved cytotoxicity of EGFR inhibitors in the KRAS mutant NSCLC cell lines.

Development and validation of a robust and sensitive HPLC-MS/MS method for the quantitation of MRTX849 in plasma and its application in pharmacokinetics

MRTX849 is a novel, highly selective, targeted inhibitor of KRAS (G12C), which significantly improves the objective response rate in patients with advanced solid tumors. However, neither an analytical HPLC-MS/MS assay nor pharmacokinetics has been reported for MRTX849 in plasma. In the present study, chromatography was accomplished on a reversed phase C₁₈ column (50 × 2.1 mm, 3.5 μm). The limit of detection of MRTX849 was 0.02 ng mL^-1 at S/N ≥ 3. Only 20 μL of plasma was utilized for accurate quantitation. The optimized analytical assay was fully validated and verified in accordance with guidelines. The calibration curve for MRTX849 was linear with a correlation coefficient >0.99 in the range of 0.05-200 ng mL^-1. The intra- and inter-day accuracy and precision were all within ±10%. The matrix effect and recovery were consistent and acceptable under several quality control concentrations. This HPLC-MS/MS method was successfully applied for a pharmacokinetic study of MRTX849 at a dose of 15 mg kg^-1.

Targeting KRAS Mutant in Non-Small Cell Lung Cancer: Novel Insights Into Therapeutic Strategies

Although KRAS-activating mutations represent the most common oncogenic driver in non-small cell lung cancer (NSCLC), various attempts to inhibit KRAS failed in the past decade. KRAS mutations are associated with a poor prognosis and a poor response to standard therapeutic regimen. The recent development of new therapeutic agents (i.e., adagrasib, sotorasib) that target specifically KRAS G12C in its GDP-bound state has evidenced an unprecedented success in the treatment of this subgroup of patients. Despite providing pre-clinical and clinical efficacy, several mechanisms of acquired resistance to KRAS G12C inhibitors have been reported. In this setting, combined therapeutic strategies including inhibition of either SHP2, SOS1 or downstream effectors of KRAS G12C seem particularly interesting to overcome acquired resistance. In this review, we will discuss the novel therapeutic strategies targeting KRAS G12C and promising approaches of combined therapy to overcome acquired resistance to KRAS G12C inhibitors.

Understanding and drugging RAS: 40 years to break the tip of the iceberg

Several cancers and rare genetic diseases are caused by dysregulation in the RAS signaling pathway. RAS proteins serve as molecular switches that regulate pathways involved in cellular growth, differentiation and survival. These pathways have been an intense area of investigation for four decades, since the initial identification of somatic RAS mutations linked to human cancers. In the past few years, inhibitors against several RAS effectors, as well as direct inhibitors of the K-RAS mutant G12C, have been developed. This Special Issue in DMM includes original Research articles on RAS-driven cancers and RASopathies. The articles provide insights into mechanisms and biomarkers, and evaluate therapeutic targets. Several articles also present new disease models, whereas others describe technologies or approaches to evaluate the function of RAS in vivo. The collection also includes a series of Review articles on RAS biology and translational aspects of defining and treating RAS-driven diseases. In this Editorial, we summarize this collection and discuss the potential impact of the articles within this evolving area of research. We also identify areas of growth and possible future developments.

Summary: This Editorial introduces DMM’s new Special Issue on the RAS pathway. The Guest Editors reflect on the impact of the featured articles on the landscape of the RAS field.

A Breakthrough Brought about by Targeting KRASG12C: Nonconformity Is Punished

Simple Summary

KRAS is the most common oncogene in human cancers and has long been considered ‘‘undruggable’’—that is, until recently, when covalent inhibitors that selectively target KRAS^G12C substitution were developed. The satisfactory results of multicenter clinical trials has led to the recent approval of therapy with KRAS^G12C inhibitors. Although KRAS^G12C allele-specific drugs have greatly improved the clinical outlook for patients with KRAS^G12C tumors, particularly lung adenocarcinomas, in which the KRAS^G12C mutant is most prevalent compared with other KRAS mutations, inevitable challenges, such as intrinsic and acquired drug resistance, must be overcome to maximize the efficacy of KRAS^G12C inhibitor therapy. Recent studies have shown that compensatory signaling pathways, such as the PI3K/AKT/mTOR pathway, and epigenetic reprogramming, e.g., epithelial-to-mesenchymal transition (EMT), are common mechanisms that mediate intrinsic resistance to KRAS^G12C inhibitors, whereas acquired resistance and ensuing recurrent disease can arise when cancer cells acquire secondary mutations in the KRAS protein that impair the covalent binding of KRAS^G12C inhibitors. The identification and targeting of KRAS^G12C inhibitor resistance mechanisms holds promise for novel strategies to effectively treat patients with KRAS^G12C-mutant cancers.

Abstract

KRAS is the most frequently mutated oncogene in lung carcinomas, accounting for 25% of total incidence, with half of them being KRAS^G12C mutations. In past decades, KRAS enjoyed the notorious reputation of being untargetable—that is, until the advent of G12C inhibitors, which put an end to this legend by covalently targeting the G12C (glycine to cysteine) substitution in the switch-II pocket of the protein, inhibiting the affinity of the mutant KRAS with GTP and subsequently the downstream signaling pathways, such as Raf/MEK/ERK. KRAS^G12C-selective inhibitors, e.g., the FDA-approved AMG510 and MRTX849, have demonstrated potent clinical efficacy and selectivity in patients with KRAS^G12C-driven cancers only, which spares other driver KRAS mutations (e.g., G12D/V/S, G13D, and Q61H) and has ushered in an unprecedented breakthrough in the field in recent decades. However, accumulating evidence from preclinical and clinical studies has shown that G12C-targeted therapeutics as single agents are inevitably thwarted by drug resistance, a persistent problem associated with targeted therapies. A promising strategy to optimize G12C inhibitor therapy is combination treatments with other therapeutic agents, the identification of which is empowered by the insightful appreciation of compensatory signaling pathways or evasive mechanisms, such as those that attenuate immune responses. Here, we review recent advances in targeting KRAS^G12C and discuss the challenges of KRAS^G12C inhibitor therapy, as well as future directions.

Kirsten rat sarcoma inhibitors in clinical development against nonsmall cell lung cancer

PURPOSE OF REVIEW

The unique structure made Kirsten rat sarcoma (KRAS) 'undruggable' for quite an extended period. The functional mechanism of this small protein is well illustrated. However, there is no precision medicine for nonsmall cell lung cancer (NSCLC) patients burden with KRAS mutation. The attempts made by scientists to make challenge history against KRAS mutation and their druggable targets are worth elucidating.

RECENT FINDINGS

The appearance of orphan drug AMG510 in the market specifically targeting KRASG12C is a tremendous breakthrough. Several KRAS inhibitors are under development now. More studies focus on combo treatment of KRAS inhibition and immune checkpoint inhibitors (ICIs). Recent preclinical and clinical investigations have been reported that NSCLC patients with KRAS mutation can benefit from ICIs.

SUMMARY

The current review elucidates the development of KRAS inhibitors from basic research to clinical precision medicines. We retrospectively analyze the development of KRAS mutation targeting drugs and discuss the investigations for future development of KRAS inhibitors.

OUP accepted manuscript

Background

Cancer of unknown primary (CUP) comprises a heterogeneous collection of malignancies that are typically associated with a poor prognosis and a lack of effective treatment options. We retrospectively evaluated the clinical utility of targeted next-generation sequencing (NGS) among CUP patients to assist with diagnosis and identify opportunities for molecularly guided therapy.

Patients and Methods

Patients with a CUP at Moffitt Cancer Center who underwent NGS between January 1, 2014 and December 31, 2019, were eligible for study inclusion. Next-generation sequencing results were assessed to determine the frequency of clinically actionable molecular alterations, and chart reviews were performed to ascertain the number of patients receiving molecularly guided therapy.

Results

Ninety-five CUP patients were identified for analysis. Next-generation sequencing testing identified options for molecularly guided therapy for 55% (n = 52) of patients. Among patients with molecularly guided therapy options, 33% (n = 17) were prescribed a molecularly guided therapy. The median overall survival for those receiving molecularly guided therapy was 23.6 months. Among the evaluable patients, the median duration of treatment for CUP patients (n = 7) receiving molecular-guided therapy as a first-line therapy was 39 weeks. The median duration of treatment for CUP patients (n = 8) treated with molecularly guided therapy in the second- or later-line setting was 13 weeks. Next-generation sequencing results were found to be suggestive of a likely primary tumor type for 15% (n = 14) of patients.

Conclusion

Next-generation sequencing results enabled the identification of treatment options in a majority of patients and assisted with the identification of a likely primary tumor type in a clinically meaningful subset of patients.

Targeting Mutated KRAS Genes to Treat Solid Tumours

Kirsten rat sarcoma (KRAS) is one of the most frequently mutated oncogenes in solid tumours. It encodes an important signalling pathway that drives cellular proliferation and growth. It is frequently mutated in aggressive advanced solid tumours, particularly colorectal, lung and pancreatic cancer. Since the first mutated KRAS was discovered in the 1980s, decades of research to develop targeted inhibitors of mutant KRAS have fallen short of the task, until recently. Multiple agents are now in clinical trials, including specific mutant KRAS inhibitors, pan-KRAS inhibitors, therapeutic vaccines and other targeted inhibitors. Mutant-specific KRAS G12C inhibitors are the most advanced, with two inhibitors, adagrasib and sotorasib, achieving approval in 2021 for the second-line treatment of patients with KRAS G12C mutant lung cancer. In this review, we summarise the importance of mutant KRAS in solid tumours, prior attempts at inhibiting mutant KRAS, and the current promising targeted agents being investigated in clinical trials, along with future challenges.

Therapeutic Targets of KRAS in Colorectal Cancer

Simple Summary

Colorectal cancer is among the most common cancers in the United States. The advancement in treatment and early diagnosis have enabled a reduction in mortality from the disease among the patients with early and localized disease; however, the survival continues to be dismal in the metastatic colorectal cancers. Understanding the biological and genetic factors is crucial is making the therapeutic strategy and improving survival outcomes. One of such critical steps is the understanding of the mechanism and development of therapeutic targets against metastatic colorectal cancers bearing the KRAS mutation.

Abstract

Patients with metastatic colorectal cancer have a 5-year overall survival of less than 10%. Approximately 45% of patients with metastatic colorectal cancer harbor KRAS mutations. These mutations not only carry a predictive role for the absence of response to anti-EGFR therapy, but also have a negative prognostic impact on the overall survival. There is a growing unmet need for a personalized therapy approach for patients with KRAS-mutant colorectal cancer. In this article, we focus on the therapeutic strategies targeting KRAS- mutant CRC, while reviewing and elaborating on the discovery and physiology of KRAS.

Recent advances in lung cancer genomics: Application in targeted therapy

Genomic characterization of lung cancer has not only improved our understanding of disease biology and carcinogenesis but also revealed several therapeutic opportunities. Targeting tumor dependencies on specific genomic alterations (oncogene addiction) has accelerated the therapeutic developments and significantly improved the outcomes even in advanced stage of disease. Identification of genomic alterations predicting response to specific targeted treatment is the key to success for this "personalized treatment" approach. Availability of multiple choices of therapeutic options for specific genomic alterations highlight the importance of optimum sequencing of drugs. Multiplex gene testing has become mandatory in view of constantly increasing number of therapeutic targets and effective treatment options. Influence of genomic characteristics on response to immunotherapy further makes comprehensive genomic profiling necessary before therapeutic decision making. A comprehensive elucidation of resistance mechanisms and directed treatments have made the continuum of care possible and transformed this deadly disease into a chronic condition. Liquid biopsy-based approach has made the dynamic monitoring of disease possible and enabled treatment optimizations accordingly. Current lung cancer management is the perfect example of "precision-medicine" in clinical oncology.

Selective KRAS G12C inhibitors in non-small cell lung cancer: chemistry, concurrent pathway alterations, and clinical outcomes

Cancers harboring mutations in the Kirsten rat sarcoma homolog (KRAS) gene have been associated with poor prognosis and lack of targeted therapies. KRAS mutations occur in approximately one in four patients diagnosed with non-small cell lung cancer (NSCLC) with KRAS G12C mutations harbored at approximately 11-16%. Research into KRAS-driven tumors and analytical chemistry have borne a new class of selective small molecules against the KRAS G12C isoform. Phase II data for sotorasib (AMG510) has demonstrated a 37.1% overall response rate (ORR). Adagrasib (MRTX849) has demonstrated a 45% ORR in an early study. While single agent efficacy has been seen, initial data suggest combination approaches are an opportunity to improve outcomes. Here, we present perspectives on the initial progress in targeting KRAS G12C, examine co-mutations evident in KRAS G12C NSCLC, and comment on potential future combinatorial approaches including SHP2, SOS1, MEK, EGFR, mTOR, CDK, and checkpoint blockade which are currently being evaluated in clinical trials. As of May 28, 2021, sotorasib has achieved US FDA approval for patients with KRAS G12C mutant lung cancer after one line of a prior therapy.

Prognostic Differences of RAS Mutations: Results from the South Australian Metastatic Colorectal Registry

BACKGROUND

Effective targeting of RAS mutations has proven elusive until recently. Novel agents directly targeting KRAS G12C have shown promise in early-phase clinical trials that included patients with metastatic colorectal cancer. Prior reports have suggested that G12C mutation may be predictive of poor outcome.

OBJECTIVE

Assessment of the specific characteristics and prognostic implications of individual RAS mutation subtypes in patients with metastatic colorectal cancer.

PATIENTS AND METHODS

Retrospective review of individual RAS mutation types from the South Australian Metastatic Colorectal Registry between 2006 and 2020.

RESULTS

Of the 5165 patients entered onto the registry, 2305 (45%) had RAS mutation results available. 772 (33%) had a RAS mutation. The nature of the RAS mutation was available in 668 (87% of those with RAS mutation). Rare mutations (outside codons 12 and 13) made up 12.6% of the total. There were numerical differences in survival between the specific RAS mutation subgroups, with the longest median overall survival (30 months) observed in those with G12S mutations. However, there was no statistical difference in survival when comparing the various RAS mutations, including the comparison of G12C to G12S (p = 0.38). Patients with cancer harbouring rare RAS mutations had a median survival of 30 months.

CONCLUSIONS

Whilst the G12S mutation was associated with the longest survival numerically, the observed survival for patients with the most common RAS mutations (G12C, G12V, G12A, G12D and G13D) did not significantly differ.