RAS as a positive predictive biomarker: focus on lung and colorectal cancer patients

Investigating the Pathogenicity of Uncommon KRAS Mutations and Their Association with Clinicopathologic Characteristics in Patients with Colorectal Cancer

Kirsten rat sarcoma viral oncogene homolog (KRAS) somatic mutations occur in 30% to 40% of patients with colorectal cancer (CRC). These were thought to equally affect prognosis and resistance to anti-epidermal growth factor receptor agents; however, recent data show the activity of KRAS-G12C and pan-RAS inhibitors. The effects of uncommon KRAS (uKRAS) variants are largely unexplored. The distribution and pathogenicity of uKRAS mutations and their relationship with patients' clinicopathologic features were assessed. A total of 2427 CRCs were profiled for KRAS using next-generation sequencing (NGS). The study and control groups included patients with uKRAS (<1% frequency in CRC data sets on cBioPortal) and canonical KRAS mutations, respectively. In silico protein structure modifications and prediction analyses were performed by using PyMOL, trRosetta, and PolyPhen-2. uKRAS mutations affected 35 cases (1.5%), with G13C (28.6%), G12R (20%), and V14I (8.6%) being most common. Missense mutations (D33E, G12W, G12F, Q22H, Q61L, and L19F) occurred in nine cases (25.7%). Duplications (G10dup and L52_G60dup) affected two cases. Pathogenicity analyses showed that G12W, Q22R, L56V, and A130I mutations are probably damaging, with scores between 0.928 and 1.000. No differences were seen in clinicopathologic features. uKRAS mutants had lower event-free survival but no difference in overall survival compared with controls. Although these data are hypothesis generating and need further confirmation, they highlight the importance of NGS-based profiling to identify CRC patients with uKRAS mutations as candidates for personalized therapy.

The Potential Treatment Options and Combination Strategies of KRAS-Mutated Lung Cancer

In non-small cell lung cancer (NSCLC), Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are found in up to 30% of all cases, with the most prevalent mutations occurring in codons 12 and 13. The development of KRAS-targeted drugs like sotorasib and adagrasib has generated significant excitement in the clinical arena, offering new therapeutic options. Their potential for combination with other treatments broadens the scope for clinical exploration. Acquired resistance to KRAS exon 2 p.G12C inhibitors is a significant challenge, with several reported mechanisms. In this scenario, combination therapy strategies that include targeting Src Homology Region 2 Domain-Containing Phosphatase-2 (SHP2), Son of Sevenless Homolog 1 (SOS1), or downstream effectors of KRAS exon 2 p.G12C are showing promise in overcoming such resistance. However, the efficacy of immune checkpoint inhibitors in this context still requires comprehensive evaluation. The response to anti-Programmed Cell Death Protein 1/Programmed Cell Death Protein 1 Ligand (anti-PD-1/PD-L1) drugs in NSCLC may be significantly influenced by co-occurring mutations, underscoring the need for a personalized approach to treatment based on the specific genetic profile of each tumor.

Novel drug delivery systems in colorectal cancer: Advances and future prospects

Colorectal cancer (CRC) is an abnormal proliferation of cells within the colon and rectum, leading to the formation of polyps and disruption of mucosal functions. The disease development is influenced by a combination of factors, including inflammation, exposure to environmental mutagens, genetic alterations, and impairment in signaling pathways. Traditional treatments such as surgery, radiation, and chemotherapy are often used but have limitations, including poor solubility and permeability, treatment resistance, side effects, and post-surgery issues. Novel Drug Delivery Systems (NDDS) have emerged as a superior alternative, offering enhanced drug solubility, precision in targeting cancer cells, and regulated drug release. Thereby addressing the shortcomings of conventional therapies and showing promise for more effective CRC management. The present review sheds light on the pathogenesis, signaling pathways, biomarkers, conventional treatments, need for NDDS, and application of NDDS against CRC. Additionally, clinical trials, ongoing clinical trials, marketed formulations, and patents on CRC are also covered in the present review.

Development of a genome atlas for discriminating benign, preinvasive, and invasive lung nodules

To tackle misdiagnosis in lung cancer screening with low-dose computed tomography (LDCT), we aimed to compile a genome atlas for differentiating benign, preinvasive, and invasive lung nodules and characterize their molecular pathogenesis. We collected 432 lung nodule tissue samples from Chinese patients, spanning benign, atypical adenomatous hyperplasia (AAH), adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and invasive adenocarcinoma (IA). We performed comprehensive sequencing, examining somatic variants, gene expressions, and methylation levels. Our findings uncovered EGFR and TP53 mutations as key drivers in - early lung cancer development, with EGFR mutation frequency increasing with disease progression. Both EGFR mutations and EGF/EGFR hypo-methylation activated the EGFR pathway, fueling cancer growth. Transcriptome analysis identified four lung nodule subtypes (G1-4) with distinct molecular features and immune cell infiltrations: EGFR-driven G1, EGFR/TP53 co-mutation G2, inflamed G3, stem-like G4. Estrogen/androgen response was associated with the EGFR pathway, proposing a new therapy combining tyrosine kinase inhibitors with antiestrogens. Preinvasive nodules exhibited stem cell pathway enrichment, potentially hindering invasion. Epigenetic regulation of various genes was essential for lung cancer initiation and development. This study provides insights into the molecular mechanism of neoplastic progression and identifies potential diagnostic biomarkers and therapeutic targets for lung cancer.

Tissue- and liquid-biopsy based NGS profiling in advanced non-small-cell lung cancer in a real-world setting: the IMMINENT study

Introduction

To date, for all non-small cell lung cancer (NSCLC) cases, it is recommended to test for driver alterations to identify actionable therapeutic targets. In this light, comprehensive genomic profiling (CGP) with next generation sequencing (NGS) has progressively gained increasing importance in clinical practice. Here, with the aim of assessing the distribution and the real-world frequency of gene alterations and their correlation with patient characteristics, we present the outcomes obtained using FoundationOne (F1CDx) and FoundationLiquid CDx (F1L/F1LCDx) NGS-based profiling in a nationwide initiative for advanced NSCLC patients.

Methods

F1CDx (324 genes) was used for tissue samples, and F1L (70 genes) or F1LCDx (324 genes) for liquid biopsy, aiming to explore the real-world occurrence of molecular alterations in aNSCLC and their relationship with patients' characteristics.

Results

Overall, 232 advanced NSCLC patients from 11 Institutions were gathered [median age 63 years; never/former or current smokers 29.3/65.9%; adenocarcinoma/squamous 79.3/12.5%; F1CDx/F1L+F1LCDx 59.5/40.5%]. Alterations were found in 170 different genes. Median number of mutated genes per sample was 4 (IQR 3-6) and 2 (IQR 1-3) in the F1CDx and F1L/F1LCDx cohorts, respectively. TP53 (58%), KRAS (22%), CDKN2A/B (19%), and STK11 (17%) alterations were the most frequently detected. Actionability rates (tier I and II) were comparable: 36.2% F1CDx vs. 34% ctDNA NGS assays (29.5% and 40.9% F1L and F1LCDx, respectively). Alterations in KEAP1 were significantly associated with STK11 and KRAS, so as TP53 with RB1. Median tumor mutational burden was 6 (IQR 3-10) and was significantly higher in smokers. Median OS from metastatic diagnosis was 23 months (IQR 18.5-19.5) and significantly lower in patients harboring ≥3 gene mutations. Conditional three-year survival probabilities increased over time for patients profiled at initial diagnosis and exceeded those of individuals tested later in their clinical history after 12 months.

Conclusion

This study confirms that NGS-based molecular profiling of aNSCLC on tissue or blood samples offers valuable predictive and prognostic insights.

The biomarkers ATLAS: An audit on 1100 non-small cell lung cancer from an Italian knowledge-based database

AIMS

To date, precision medicine has revolutionized the clinical management of Non-Small Cell Lung Cancer (NSCLC). International societies approved a rapidly improved mandatory testing biomarkers panel for the clinical stratification of NSCLC patients, but harmonized procedures are required to optimize the diagnostic workflow. In this context a knowledge-based database (Biomarkers ATLAS, https://biomarkersatlas.com/) was developed by a supervising group of expert pathologists and thoracic oncologists collecting updated clinical and molecular records from about 80 referral Italian institutions. Here, we audit molecular and clinical data from n = 1100 NSCLC patients collected from January 2019 to December 2020.

METHODS

Clinical and molecular records from NSCLC patients were retrospectively collected from the two coordinating institutions (University of Turin and University of Naples). Molecular biomarkers (KRAS, EGFR, BRAF, ROS1, ALK, RET, NTRK, MET) and clinical data (sex, age, histological type, smoker status, PD-L1 expression, therapy) were collected and harmonized.

RESULTS

Clinical and molecular data from 1100 (n = 552 mutated and n = 548 wild-type) NSCLC patients were systematized and annotated in the ATLAS knowledge-database. Molecular records from biomarkers testing were matched with main patients' clinical variables.

CONCLUSIONS

Biomarkers ATLAS (https://biomarkersatlas.com/) represents a unique, easily managing, and reliable diagnostic tool aiming to integrate clinical records with molecular alterations of NSCLC patients in the real-word Italian scenario.

Racial disparities in colorectal cancer clinicopathological and molecular tumor characteristics: a systematic review

PURPOSE

African Americans have the highest colorectal cancer (CRC) mortality of all racial groups in the USA, which may relate to differences in healthcare access or advanced stage at diagnosis. Recent evidence indicates that differences in tumor characteristics may also underlie disparities in mortality. To highlight recent findings and areas for investigation, we completed the first systematic review of racial disparities in CRC tumor prognostic markers, including clinicopathological markers, microsatellite instability (MSI), oncogene mutations, and novel markers, including cancer stem cells and immune markers.

METHODS

Relevant studies were identified via PubMed, limited to original research published within the last 10 years. Ninety-six articles were identified that compared the prevalence of mortality-related CRC tumor characteristics in African Americans (or other African ancestry populations) to White cases.

RESULTS

Tumors from African ancestry cases are approximately 10% more likely to contain mutations in KRAS, which confer elevated mortality and resistance to epidermal growth factor receptor inhibition. Conversely, African Americans have approximately 50% lower odds for BRAF-mutant tumors, which occur less frequently but have similar effects on mortality and therapeutic resistance. There is less consistent evidence supporting disparities in mutations for other oncogenes, including PIK3CA, TP53, APC, NRAS, HER2, and PTEN, although higher rates of PIK3CA mutations and lower prevalence of MSI status for African ancestry cases are supported by recent evidence. Although emerging evidence suggests that immune markers reflecting anti-tumor immunity in the tumor microenvironment may be lower for African American cases, there is insufficient evidence to evaluate disparities in other novel markers, cancer stem cells, microRNAs, and the consensus molecular subtypes.

CONCLUSION

Higher rates of KRAS-mutant tumors in in African Americans may contribute to disparities in CRC mortality. Additional work is required to understand whether emerging markers, including immune cells, underlie the elevated CRC mortality observed for African Americans.

Sotorasib in KRASp.G12C mutated advanced NSCLC: Real-world data from the Italian expanded access program

BACKGROUND

Sotorasib showed a significant improvement of progression free survival (PFS), safety and quality of life over docetaxel in patients with KRASp.G12C-mutated advanced non-small-cell lung cancer (NSCLC) within the CodeBreak-200 study. Here we report real-world efficacy and tolerability data from NSCLC patients who received sotorasib within the Italian expanded access program (EAP).

METHODS

Sotorasib (960 mg, orally, once daily) was available on physician request for KRASp.G12C mutant advanced NSCLC patients. Clinical-pathological and molecular data were collected from the Italian ATLAS real-world registry. Patients underwent CT-scan and responses were evaluated by RECIST criteria. Efficacy and tolerability outcomes have been assessed.

RESULTS

A total of 196 advanced NSCLC patients were treated across 30 Italian centers. Median age was 69 years old (range 33-86). Most patients were male (61 %), former (49 %) or current smokers (43 %), with ECOG-PS 0/1 (84 %) and adenocarcinoma subtype (90 %). 45 % and 32 % of patients received sotorasib in 2nd and 3rd line, respectively. Overall, response rate was 26 % and the median duration of response was 5.7 months (95 % CI: 4.4-7.0). Median PFS and OS were 5.8 months (95 % CI: 5 - 6.5) and 8.2 months (95 % CI: 6.3 - 9.9). Grade 3-4 TRAEs occurred in 16.5 % of patients, with Grade ≥ 3 liver enzyme increase and TRAEs-related discontinuation reported in 12 % and 4.6 % of cases.

CONCLUSION

Real-world data from the Italian EAP confirm the tolerability and effectiveness of sotorasib in patients with KRASp.G12C-mutated advanced NSCLC and highlight the value of the national ATLAS network as source of real-world evidence driving the clinical management of NSCLC patients.

Mesonephric-like adenocarcinoma of the female genital tract: possible role of KRAS-targeted treatment-detailed molecular analysis of a case series and review of the literature for targetable somatic KRAS-mutations

PURPOSE

Mesonephric-like adenocarcinomas (MLA) of the female genital tract represent a rare and relatively recently described neoplasm exhibiting characteristic morphologic and immunohistochemical findings commonly associated with a KRAS-mutation. Most cases display an aggressive clinical behavior, but knowledge about treatment approaches is limited, especially for targeting KRAS.

METHODS

We report a series of eight cases with a detailed molecular analysis for KRAS. These cases as well as the data of previously published cases with detailed information regarding KRAS-mutational events were reviewed for a potential targeted approach and its prognostic impact.

RESULTS

Both the uterine and ovarian MLA harbor a somatic KRAS-mutation in about 85% of the reported cases, affecting the hotspot codons 12 and 13. 15.7% of the endometrial and 15.6% of ovarian MLA are wild type for KRAS. A p.G12A-alteration was seen in 5.6% (5/89) of the endometrial and in 6.2% (2/32) of the ovarian tumors, for p.G12C in 7.9% and 6.2%, for p.G12D in 32.6% and 34.5% and for p.G12V in 36% and 37.5%, respectively. Very limited data are available regarding the prognostic impact of different mutational sites within the KRAS-gene without significant prognostic impact.

CONCLUSION

Because of a specific p.G12C-KRAS somatic mutation, only the minority of MLA (7.9% with uterine and 6.2% with ovarian primary) are potentially targetable by sotarasib in that rare but aggressive subtype of adenocarcinoma of the female genital tract. Until now, the different location of a somatic KRAS-mutation is of no prognostic impact.

The ideal reporting of RAS testing in colorectal adenocarcinoma: a pathologists' perspective

RAS gene mutational status represents an imperative predictive biomarker to be tested in the clinical management of metastatic colorectal adenocarcinoma. Even if it is one of the most studied biomarkers in the era of precision medicine, several pre-analytical and analytical factors may still impasse an adequate reporting of RAS status in clinical practice, with significant therapeutic consequences. Thus, pathologists should be aware on the main topics related to this molecular evaluation: (i) adopt diagnostic limit of detections adequate to avoid the interference of sub-clonal cancer cell populations; (ii) choose the most adequate diagnostic strategy according to the available sample and its qualification for molecular testing; (iii) provide all the information regarding the mutation detected, since many RAS mutation-specific targeted therapeutic approaches are in development and will enter into routine clinical practice. In this review, we give a comprehensive description of the current scenario about RAS gene mutational testing in the clinic focusing on the pathologist's role in patient selection for targeted therapies.

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.

The evolving landscape of anatomic pathology

Anatomic pathology has changed dramatically in recent years. Although the microscopic assessment of tissues and cells is and will remain the mainstay of cancer diagnosis molecular profiling has become equally relevant. Thus, to stay abreast of the evolving landscape of today's anatomic pathology, modern pathologists must be able to master the intricate world of predictive molecular pathology. To this aim, pathologists have had to acquire additional knowledge to bridge the gap between clinicians and molecular biologists. This new role is particularly important, as cases are now collegially discussed in molecular tumor boards (MTBs). Moreover, as opposed to traditional pathologists, modern pathologists have also adamantly embraced innovation while keeping a constant eye on tradition. In this article, we depict the highlights and shadows of the upcoming "Anatomic Pathology 2.0" by placing particular emphasis on the pathologist's growing role in the management of cancer patients.

Biomarkers of Favorable vs. Unfavorable Responses in Locally Advanced Rectal Cancer Patients Receiving Neoadjuvant Concurrent Chemoradiotherapy

Colorectal cancer is the second leading cause of cancer death globally. The gold standard for locally advanced rectal cancer (LARC) nowadays is preoperative concurrent chemoradiation (CCRT). Approximately three quarters of LARC patients do not achieve pathological complete response and hence suffer from relapse, metastases and inevitable death. The exploration of trustworthy and timely biomarkers for CCRT response is urgently called for. This review focused upon a broad spectrum of biomarkers, including circulating tumor cells, DNA, RNA, oncogenes, tumor suppressor genes, epigenetics, impaired DNA mismatch repair, patient-derived xenografts, in vitro tumor organoids, immunity and microbiomes. Utilizing proper biomarkers can assist in categorizing appropriate patients by the most efficient treatment modality with the best outcome and accompanied by minimal side effects. The purpose of this review is to inspect and analyze accessible data in order to fully realize the promise of precision oncology for rectal cancer patients.

Single agent VS-6766 or VS-6766 plus defactinib in KRAS-mutant non-small-cell lung cancer: the RAMP-202 phase II trial

KRAS mutations occur in approximately 30% of lung adenocarcinomas, mainly in codon 12 (83% of cases), p.G12C being the prevalent one (40%), followed by p.G12V and p.G12D (22 and 16%, respectively). Treatment options for advanced KRAS mutant non-small-cell lung cancer (KRAS-MT NSCLC) are limited to chemotherapy and immune checkpoint inhibitors (CPIs). However, clinical trials exploring specific targeted agents are expected to change the treatment landscape of this disease. Here, we describe the design and scientific rationale of the randomized, phase II, open label, RAMP-202 study, which will evaluate the efficacy and safety of VS-6766 versus VS-6766 in combination with defactinib in advanced KRAS-MT NSCLC patients after failure of prior platinum-based chemotherapy and CPI.

Daily Practice Assessment of KRAS Status in NSCLC Patients: A New Challenge for the Thoracic Pathologist Is Right around the Corner

Simple Summary

RAS mutation is the most frequent oncogenic alteration in human cancers and KRAS is the most frequently mutated, notably in non-small cell lung carcinomas (NSCLC). Various attempts to inhibit KRAS in the past were unsuccessful in these latter tumors. However, recently, several small molecules (AMG510, MRTX849, JNJ-74699157, and LY3499446) have been developed to specifically target KRAS G12C-mutated tumors, which seems promising for patient treatment and should soon be administered in daily practice for non-squamous (NS)-NSCLC. In this context, it will be mandatory to systematically assess the KRAS status in routine clinical practice, at least in advanced NS-NSCLC, leading to new challenges for thoracic oncologists.

Abstract

KRAS mutations are among the most frequent genomic alterations identified in non-squamous non-small cell lung carcinomas (NS-NSCLC), notably in lung adenocarcinomas. In most cases, these mutations are mutually exclusive, with different genomic alterations currently known to be sensitive to therapies targeting EGFR, ALK, BRAF, ROS1, and NTRK. Recently, several promising clinical trials targeting KRAS mutations, particularly for KRAS G12C-mutated NSCLC, have established new hope for better treatment of patients. In parallel, other studies have shown that NSCLC harboring co-mutations in KRAS and STK11 or KEAP1 have demonstrated primary resistance to immune checkpoint inhibitors. Thus, the assessment of the KRAS status in advanced-stage NS-NSCLC has become essential to setting up an optimal therapeutic strategy in these patients. This stimulated the development of new algorithms for the management of NSCLC samples in pathology laboratories and conditioned reorganization of optimal health care of lung cancer patients by the thoracic pathologists. This review addresses the recent data concerning the detection of KRAS mutations in NSCLC and focuses on the new challenges facing pathologists in daily practice for KRAS status assessment.

Targeting KRAS in NSCLC: Old Failures and New Options for "Non-G12c" Patients

Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) gene mutations are among the most common driver alterations in non-small cell lung cancer (NSCLC). Despite their high frequency, valid treatment options are still lacking, mainly due to an intrinsic complexity of both the protein structure and the downstream pathway. The increasing knowledge about different mutation subtypes and co-mutations has paved the way to several promising therapeutic strategies. Despite the best results so far having been obtained in patients harbouring KRAS exon 2 p.G12C mutation, even the treatment landscape of non-p.G12C KRAS mutation positive patients is predicted to change soon. This review provides a comprehensive and critical overview of ongoing studies into NSCLC patients with KRAS mutations other than p.G12C and discusses future scenarios that will hopefully change the story of this disease.

The storm of NGS in NSCLC diagnostic-therapeutic pathway: How to sun the real clinical practice

The increasing number of approved drugs along with next generation sequencing (NGS) technologies look out as potential revolution of biomolecular characterization of non-small-cell lung cancer (NSCLC). Nevertheless, several aspects impact on success rate of NGS in clinical practice: a multidisciplinary approach and thorough knowledge of strengths and limits of each technologic diagnostic tool are required. Crucial preliminary step is the selection of the best available sample before testing, aware of clinical condition and setting of disease. Genomic data should be than integrated in the clinical context and matched with available therapeutic options; Molecular Tumor Boards (MTB) are worldwide emerging interdisciplinary groups implemented to transfer the impact of precision medicine in clinical practice. In order to guarantee equity in treatment, these considerations should find their application widely and rapidly. Aim of this review is offering an overview of emerging biomarkers, relative upcoming targeted drugs, and new diagnostic chances with an authors' perspective about a real-life diagnostic-therapeutic algorithm useful for daily clinical practice.

Cetuximab promotes RSL3-induced ferroptosis by suppressing the Nrf2/HO-1 signalling pathway in KRAS mutant colorectal cancer

Cetuximab is approved for the treatment of metastatic colorectal cancer (mCRC) with RAS wild-type. Nevertheless, the prognosis remains poor and the effectiveness of cetuximab is limited in KRAS mutant mCRC. Recently, emerging evidence has shown that ferroptosis, a newly discovered form of nonapoptotic cell death, is closely related to KRAS mutant cells. Here, we further investigated whether cetuximab-mediated regulation of p38/Nrf2/HO-1 promotes RSL3-induced ferroptosis and plays a pivotal role in overcoming drug resistance in KRAS mutant colorectal cancer (CRC). In our research, we used two KRAS mutant CRC cell lines, HCT116 and DLD-1, as models of intrinsic resistance to cetuximab. The viability of cells treated with the combination of RSL3 and cetuximab was assessed by the CCK-8 and colony formation assays. The effective of cetuximab to promote RSL3-induced ferroptosis was investigated by evaluating lipid reactive oxygen species accumulation and the expression of the malondialdehyde and the intracellular iron assay. Cetuximab therapy contributed to regulating the p38/Nrf2/HO-1 axis, as determined by western blotting and transfection with small interfering RNAs. Cetuximab promoted RSL3-induced ferroptosis by inhibiting the Nrf2/HO-1 in KRAS mutant CRC cells, and this was further demonstrated in a xenograft nude mouse model. Our work reveals that cetuximab enhances the cytotoxic effect of RSL3 on KRAS mutant CRC cells and that cetuximab enhances RSL3-induced ferroptosis by inhibiting the Nrf2/HO-1 axis through the activation of p38 MAPK.

Expression of Immuno-Oncologic Biomarkers Is Enriched in Colorectal Cancers and Other Solid Tumors Harboring the A59T Variant of KRAS

The molecular heterogeneity of KRAS is well established, with a pool of variants comprising >75% of all known mutations; this pool includes mutations in classic codons 12, 13, and 61, as well as 146 and 117. In addition, there are rare variants that are more frequently encountered clinically due to the advances in next-generation sequencing and more widespread implementation of All-RAS sequencing over the past five years. We have previously identified a missense variant of KRAS, A59T, in a patient with CRC that was associated with a response to an epidermal growth factor inhibitor when added to chemotherapy, supporting the hypothesis that distinct biochemical impacts of different KRAS mutations may produce varied responses to targeted therapy. In this study, we explored a large genomic database comprising 17,909 cases of CRC to determine the prevalence of the A59T mutation and characterized the concurrent genomic alterations associated with this variant in more detail, particularly in relation to the expanding set of potential predictive immuno-oncologic biomarkers. We identified 14 cases of A59 mutations in this dataset (0.08% prevalence). We evaluated the prevalence of high tumor mutation burden (TMB), positive PD-L1 expression, and microsatellite instability-high/mismatch repair-deficiency (MSI-H/dMMR) using both next generation sequencing (NGS) and immunohistochemistry (IHC). The genomic features of pertinent signaling pathways were also described, including RAS pathway, chromatin remodeling, DDR, hedgehog signaling, PI3K, receptor tyrosine kinases, signal transduction, TGF-beta, TP53, and WNT. We uncovered a high level of association of predictive markers of responsiveness to checkpoint inhibition and potentially other forms of immunotherapy, with nearly half of all cases harboring microsatellite instability as assessed using NGS. A59T was also detected in 11 additional cancer types, most prominently in cases of gynecologic or other gastrointestinal sites of origin. This study provides supportive evidence that A59T, and possibly other similarly rare KRAS variants, co-occur with predictive biomarkers of response to immunotherapy.

Case Report: Outcome of Osimertinib Treatment in Lung Adenocarcinoma Patients With Acquired KRAS Mutations

Background

Osimertinib belongs to the third-generation epidermal growth factor receptor tyrosine kinase inhibitor that has shown positive effects in treating lung adenocarcinoma cancer. However, the subsequent resistance to Osimertinib has become a clinical challenge.

Case Presentation

We present two lung adenocarcinoma cases that developed a resistance to Osimertinib. Among them, one patient attained both KRAS exon 2 and exon 3 mutations and was given paclitaxel (albumin-bound) plus carboplatin. The other patient exhibited a KRAS exon 3 mutation, so the paclitaxel (albumin-bound) plus nivolumab was administered. Eventually, the second patient manifested a better clinical outcome than the first.

Conclusion

These results provide supporting evidence that KRAS exon 3 (R68S) mutations may be associated with Osimertinib resistance in lung adenocarcinoma patients. This further reveals the relationship between subtypes of acquired KRAS mutations and the effect of therapeutic approaches. Moreover, the combination of chemotherapy and immune checkpoint inhibitors may generate a satisfying disease control.

Concomitant Mutations G12D and G13D on the Exon 2 of the KRAS Gene: Two Cases of Women with Colon Adenocarcinoma

Colorectal cancer (CRC) is rapidly increasing representing the second most frequent cause of cancer-related deaths. From a clinical-molecular standpoint the therapeutically management of CRC focuses on main alterations found in the RAS family protein, where single mutations of KRAS are considered both the hallmark and the target of this tumor. Double and concomitant alterations of KRAS are still far to be interpreted as molecular characteristics which could potentially address different and more personalized treatments for patients. Here, we firstly describe the case of two patients at different stages (pT2N0M0 and pT4cN1cM1) but similarly showing a double concurrent mutations G12D and G13D in the exon 2 of the KRAS gene, normally mutually exclusive. We also evaluated genetic testing of dihydropyrimidine dehydrogenase (DPYD) and microsatellite instability (MSI) by real-time PCR and additional molecular mutations by next generation sequencing (NGS) which resulted coherently to the progression of the disease. Accordingly, we reinterpreted and discuss the clinical history of both cases treated as single mutations of KRAS but similarly progressing towards a metastatic asset. We concluded that double mutations of KRAS cannot be interpreted as univocal genomic alterations and that they could severely impact the clinical outcome in CRC, requiring a tighter monitoring of patients throughout the time.