INTRODUCTION:Breast cancer in young adults (YA) aged 20-40 years has distinct clinical and biological traits compared with older patients. This study evaluated the genomic landscape of metastatic breast cancers (MBC) among YA. METHODS:Patients with MBC enrolled in the STING molecular profile platform (NCT04932525) between 2021 and May 2023 were included. Clinical and genomic features were analyzed by age (≤40 vs > 40 years). Tumor profiling used the FoundationOne Liquid CDx assay (324 genes) at baseline or later in the disease course. Variant frequencies were compared across age groups. RESULTS:Of 432 eligible patients, 68 (16 %) were YA. Among 37 YA with hormone receptor positive (HR+) BC, frequent alterations included TP53 (39 %), ESR1 (27 %), PIK3CA (25 %), FGFR3 (18 %), FGFR4 (18 %), FGFR19 (18 %), CCND1 (18 %). Compared with older patients, YA with HR + tumors had fewer RB1 (7 % vs 8 %; p = 0.03) and PIK3CA (25 % vs 31 %; p = 0.03) alterations. Among 28 YA with triple negative BC, the most common alterations were TP53 (100 %), PTEN (26 %), BRCA1 (22 %), RB1 (17 %). PTEN mutations were more frequent among YA with TNBC than older patients (26 % vs 8 %; p = 0.009). Tiers I-III genomic alterations according to the ESMO scale of clinical actionability (ESCAT) were identified in 54 YA (79 %), including 48 tiers I-II alterations comprising ESR1 (n = 12), gBRCA1/2 (n = 11), PIK3CA (n = 13). CONCLUSIONS:ESCAT tiers I-III alterations were reported in 79 % YA with MBC which supports the role of molecular profiling in YA. The differences detected in the genomic profiles of YA with BC and older patients may allude to potential different underlying disease biology.

3061 Background: Large cfDNA panels used for somatic profiling can incidentally reveal pathogenic variants of potential germline origin, with implications for patient management and hereditary cancer risk assessment. Methods: Between December 18 th , 2020 and July 22 nd , 2025, a weekly molecular tumor board reviewed cfDNA sequencing data from 8353 patients with advanced solid tumors treated at Gustave Roussy using the FoundationOne Liquid CDx panel, within the prospective STING trial (NCT04932525). We evaluated the yield, clinical relevance, and confirmatory outcomes of an MTB-governed workflow to flag putative germline pathogenic variants (PGPVs) from routine cfDNA profiling in advanced cancers. Across the 324 covered genes, we selected a list of 31 known hereditary cancer genes and 7 emerging candidates. Patients without prior germline confirmation were referred for genetic counseling and confirmatory testing on an independent sample. Turnaround times were compared with the conventional germline pathway. Results: Among 8,353 patients (mean age 62 years), 445 (5.3%) carried 471 PGPVs, including 23 patients with more than 2 variants. The most frequently implicated genes were BRCA2 (n=101), MUTYH (n=81) and BRCA1 (n=62). Overall, 54.6% of PGPVs were incidental findings (257/471); among incidental findings, 51.0% were clinically actionable (131/257), corresponding to 27.8% of all PGPVs (131/471). Germline status was confirmed in 172 patients (86 known prior to cfDNA profiling and 86 confirmed following cfDNA-guided referrals, including 60 incidental findings of which 52 were actionable; 14 variants (11 patients) were not confirmed and 6 were pending. For variants first flagged through cfDNA, the mean interval from liquid biopsy prescription to confirmatory germline report was 2 months, compared with 6 months through the conventional pathway. In evaluable paired cases, cfDNA showed high diagnostic performance for identifying germline findings (sensitivity 98.3%, specificity 97.4%). Conclusions: In an advanced pan-cancer real-world cohort, an MTB-governed cfDNA workflow identified PGPVs in 5% of patients, with over half representing incidental findings and 28% of all PGPVs being actionable. cfDNA profiling can accelerate referral and confirmation of hereditary cancer risk when coupled with expert interpretation and confirmatory germline testing, while acknowledging limitations for certain alterations.

BACKGROUND:Immune checkpoint blockade (ICB) has transformed cancer treatment, yet many patients experience poor outcomes. Identifying patients at high risk of poor outcomes under ICB-containing therapies remains a major clinical challenge. OBJECTIVES:To identify baseline factors associated with poor outcomes under ICB-containing therapies and develop a prognostic score for early-phase clinical trials. METHODS:We analyzed a discovery cohort of patients with advanced solid tumors receiving ICB-containing therapies in early-phase clinical trials at Gustave Roussy Cancer Center (DITEP), derived from the prospective PREMIS study (NCT03984318). Baseline clinical and biological variables were evaluated in relation to survival outcomes, and a multivariable Cox model was used to identify independent prognostic factors. A simple five-factor prognostic score was subsequently developed using biologically relevant baseline variables and externally validated in an independent cohort from Institut Curie. RESULTS:Among 227 patients, a prognostic score incorporating liver metastases, elevated neutrophil count, elevated CRP, elevated LDH, and low lymphocyte count was developed (one point per factor, range 0-5). ECOG performance status, absolute neutrophil count, and absolute lymphocyte count remained independently associated with overall survival after adjustment. Patients with a score ≥ 3 had significantly shorter overall survival than those with a score of 0 (HR 4.10, 95% CI 1.71-10.00; p = 0.002), confirmed in external validation (HR 2.22, 95% CI 1.21-4.08; p = 0.006). The score discriminated overall survival better than RMH and LIPI, with similar performance to GRIm-Score and MDA-ICI. CONCLUSION:We developed and externally validated a simple prognostic score identifying patients at high risk of poor outcomes during ICB-containing therapies in early-phase trials. This tool may improve baseline risk stratification but should not be used as an exclusion criterion for enrollment.

INTRODUCTION:With the advances in artificial intelligence (AI) and precision medicine, radiomics has emerged as a promising tool in the field of oncology. Radiogenomics integrates radiomics with genomic data, potentially offering a non-invasive method for identifying biomarkers relevant to cancer therapy. Liquid biopsy (LB) has further revolutionized cancer diagnostics by detecting circulating tumor DNA (ctDNA), enabling real-time molecular profiling. This study explores the integration of radiomics and LB to predict genomic alterations in solid tumors, including lung, colon, pancreatic, and prostate cancers. METHODS:A retrospective study was conducted on 418 patients from the STING trial (NCT04932525), all of whom underwent both LB and CT imaging. Predictive models were developed using an XGBoost logistic classifier, with statistical analysis performed to compare tumor volumes, lesion counts, and affected organs across molecular subtypes. Performance was evaluated using area under the curve (AUC) values and cross-validation techniques. RESULTS:Radiomic models demonstrated moderate-to-good performance in predicting genomic alterations. KRAS mutations were best identified in pancreatic cancer (AUC=0.97), while moderate discrimination was noted in lung (AUC=0.66) and colon cancer (AUC=0.64). EGFR mutations in lung cancer were detected with an AUC of 0.74, while BRAF mutations showed good discriminatory ability in both lung (AUC=0.79) and colon cancer (AUC=0.76). In the radiomics predictive model, AR mutations in prostate cancer showed limited discrimination (AUC = 0.63). CONCLUSION:This study highlights the feasibility of integrating radiomics and LB for non-invasive genomic profiling in solid tumors, demonstrating significant potential in patient stratification and personalized oncology care. While promising, further prospective validation is required to enhance the generalizability of these models.

Clinical research provides an important gateway to therapeutic innovation and, in many cases, national participation in trials can facilitate the future availability of new treatments in the country concerned. Clinical research activity in general is declining in France, especially in terms of industry-led trials; the only exception being early-phase cancer trials. There is an urgent need to boost the level of French participation in major international trials, although this will require a marked improvement in recruitment performance. Although the many factors contributing to the mediocre performance of France merit discussion, the overriding necessity is to bring forward solutions for increasing the level of participation in clinical trials going forward. It is against this background that we propose these recommendations for facilitating and increasing overall enrolment. There are a number of potential ways in which improvements could be achieved, beginning with identifying eligible patients and offering them the opportunity to take part in clinical trials, either through greater engagement by healthcare professionals or the development of decentralised trials. Other opportunities include optimising territorial coverage through inter-hospital networks or clinical trials centre networks, strengthening and improving clinical trials centre organisational structures by introducing AI-driven patient pre-screening tools, and lastly reprofiling some of the roles involved in clinical research and the provision of associated training. While some of these recommendations require regulatory changes, the majority could be implemented immediately, and would provide a rapid response to this major strategic challenge.

The advent of advanced biomolecular technologies for detecting molecular and genomic signatures of individual tumors has transformed oncology care, introducing proven methodologies that can inform treatment with matched targeted therapies and predict response at the individual patient level. However, access to these technologies has been hampered by multiple barriers, most notably price and obtainability. Other barriers include lack of knowledge of available technologies, concerns about value, and outdated infrastructures that impede critical operations within the clinic or laboratory. Accessibility barriers to advanced biomolecular testing are critically important to patient care, as new technological advances in molecular medicine continue to outpace the implementation of solutions. Given the proven evidence for improved patient outcomes with precision oncology medicines, it is imperative to understand the value afforded by these technologies. The purpose of this narrative review is to describe existing and emerging barriers to access and present a "roadmap to access" that will facilitate the urgently needed discussions to identify solutions for improving access. Implementation of these solutions will raise awareness of available technologies and treatments and their prognostic significance, improve evidence collection for demonstration of value, and fortify clinical and laboratory infrastructure and operations.

Molecular profiling is critical for personalizing cancer treatments, with approaches spanning from tissue DNA sequencing to liquid biopsy analysis of circulating tumor DNA (ctDNA). While both techniques provide valuable insights, the comparative clinical impact of tissue-based genomic profiling versus ctDNA-based profiling in tailoring treatments remains insufficiently explored. We are investigating the comparison between wide genomic sequencing of tissue and ctDNA profiling with a large panel to evaluate their ability to guide treatment decisions in cancer patients. At Gustave Roussy, Comprehensive genomic profiling (CGP) on ctDNA is routinely used to guide treatment selection for patients with advanced metastatic cancers, in therapy failure after 1st line. In the same patient population, Extensive Genome Sequencing (EGS: WGS, WES, WTS) can also be proposed, from fresh frozen material. To assess the relevance of these approaches, we identified a cohort of patients from Gustave Roussy with prescription of both EGS on fresh frozen tumor tissue and CGP on ctDNA, (Foundation One Liquid CDx Assay, 324 genes, tumor mutational burden [TMB], microsatellite instability) and were discussed in Gustave Roussy’s molecular tumor board. This study will evaluate and compare the capacity of these methods to tailor treatment strategies in this population Between April 2021 and Oct 2024, 202 patients with both EGS and CGP were identified. Failure rate of EGS on tissue was 18.8% (due to lack of sufficient tissue for 36 patients and non-contributive for 2 patients). Conversely, failure rate of CGP on ctDNA was 8.4% (non-contributive for 17 patients). Out of the 147 evaluable patients, main tumor types were HNSCC (n=32, 22%), endocrine tumors (n=26, 18%), gynecological tumors (n=16, 11%), sarcoma (n=13, 9%) and pancreatic tumors (n=14, 9%). The median turnaround time between reception of the sample and results from the molecular analysis was 10 [5:37] days for CGP versus 95 [25:724] days for EGS. We compared the therapeutic recommendations provided with both analyses, after discussion during a molecular tumor board. Independently of the time between tissue sampling and liquid biopsy (median: 111 days), treatment recommendations were concordant in 83% of cases. For 13 cases (8.8%), alterations were identified only on tissue (deletion (n=4), mutation (n=6), genomic signature (n=3)). Our analysis on a small cohort of patient shows that EGS and CGP have a high concordance rate in terms of therapeutic recommendations when both are contributive. Given organizational barriers of EGS on tissue (cost, turnaround time, difficulty to obtain tumor material of sufficient quality), a sequential strategy could be interesting. Marie Morfouace, Etienne Rouleau, Marc Deloger, Ludovic Lacroix, Voreak Suybeng, Sofiane Taleb, Claudio Nicotra, Maud Ngo Camus, Fabrice Barlesi, Fabrice André, Antoine Italiano, Benjamin Besse, Arnaud Bayle. Extensive genome sequencing on tissue vs large ctDNA panel: what clinical impact [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7470.

Introduction Clonal hematopoiesis (CH) is enriched in patients with cancer and has been linked to adverse outcomes. Although often identified in routine diagnostic testing, prospective data remain limited. To guide risk stratification and therapeutic decisions, our institution launched a multidisciplinary tumor board (CH-MTB) in 2022 to review cases of clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS). Methods Patients with a history of cancer and incidental CH detection were referred from either (1) plasma cell-free DNA (cfDNA) sequencing using the FoundationOne Liquid CDx assay (NCT04932525) covering CH-related genes (ASXL1, DNMT3A, IDH1, IDH2, JAK2, MPL, MYD88, SF3B1, TET2, and U2AF1), performed for cancer management. Patients with a somatic mutation in one of these genes and variant allele frequency (VAF) ≥ 10%, or any VAF for JAK2, MPL, or MYD88, were assigned to the cfDNA cohort (all had solid tumors); or (2) presence of unexplained clonal cytopenia assessed by a 174-gene peripheral blood (PB) next-generation sequencing (NGS) panel. These patients were assigned to the PB-NGS cohort (62% solid tumors, 38% lymphoma or multiple myeloma). The Clonal Hematopoiesis Risk Score (CHRS) was calculated for mutations with VAF ≥ 2%; mutations with VAF < 2% were classified as micro-CHIP. ResultsFrom June 2022 to June 2024, 591 patients were prospectively enrolled: 374 in the cfDNA cohort and 217 in the PB-NGS cohort. Median age was 69 years; 52% were female. A history of ≥ 2 primary cancers was reported in 25%. Lung cancer (25%) and non-Hodgkin lymphoma (NHL) (32%) were the most common in the cfDNA and PB-NGS cohorts, respectively. Median treatment lines were 2 (range: 0-12). Compared to the cfDNA group, the PB-NGS patients showed higher rates of thrombocytopenia (39% vs. 6%, p < 0.01), neutropenia (15% vs. 2%, p < 0.01), anemia (59% vs. 36%, p < 0.01), macrocytosis (21% vs. 8%, p < 0.01), and elevated red cell distribution width (RDW) (34% vs. 17%, p = 0.03). Top mutations in the PB-NGS cohort included DNMT3A (47%), PPM1D (27%), TET2 (26%), TP53 (22%), and ASXL1 (12%). In the cfDNA cohort, DNMT3A (61%), TET2 (33%), ASXL1 (25%), JAK2 (25%), and MYD88 (6%) mutations predominated. Based on the CHRS, patients were low-risk (25% vs. 35%), intermediate-risk (36% vs. 22%), and high-risk (12% vs. 1%) in the PB-NGS vs. cfDNA cohorts (p < 0.001). Micro-CHIP was observed in 18% and 17%, respectively. Concordance between cfDNA and PB-NGS was assessed in 67 patients (11%) with both tests (84% collected within 1 year). Of the 132 mutations covered by both panels, 74 (56%) were detected by both, 51 (39%) only in cfDNA, and 7 (5%) only in PB-NGS. Most cfDNA-only mutations (82%) had a VAF < 2%. For mutations with VAF ≥ 2%, VAFs correlated strongly between cfDNA and PB-NGS (r = 0.77), specifically for DNMT3A (r = 0.92) and TET2 (r = 0.69). After a median follow-up of 18 months (range: 0-35), 20 new hematologic malignancies were diagnosed: 7 at first CH-MTB visit (myelodysplastic syndrome [MDS]: 2; myeloproliferative neoplasm [MPN]: 2; chronic myelomonocytic leukemia [CMML]: 1; chronic myeloid leukemia: 1; NHL: 1) and 13 during follow-up (MDS: 9; MPN: 1; MDS/MPN: 2; NHL: 1). Among the 12 with MDS or CMML, 8 had clonal evolution, 4 acquired new mutations, and 4 had TP53 alterations. Of those progressing to MDS, 64% had a high or very high IPSS-M score. Univariable analysis adjusted for cohort affiliation showed that patients with ≥ 2 treatment lines (hazard ratio [HR] = 1.8), presence of CCUS (HR = 1.8), elevated RDW (HR = 2.3), and CHRS high-risk (HR = 3.5) were at risk for shorter overall survival (OS) (p < 0.01). In multivariable analysis of CHRS components adjusted for cohort affiliation, presence of CCUS (HR = 1.7) and elevated RDW (HR = 2.1) independently predicted shorter OS (p ≤ 0.01). Competing risk analysis showed that CHRS high-risk group (HR = 11, p = 0.03), presence of ≥ 2 CHIP mutations (HR = 9.3, p < 0.01), and VAF ≥ 20% (HR = 5.7, p < 0.01) were associated with progression to hematologic malignancies. Conclusion Our MTB dedicated to CH proved the importance of early detection of hematologic malignancies in patients with cancer. CHRS high-risk group, high VAF, and multiple CHIP mutations were associated with progression to hematologic malignancies. These findings highlight the need for oncology-specific CH risk models to identify patients warranting early CHIP interception.

Anal squamous cell carcinoma (aSCC) is a rare, predominantly HPV-driven cancer with limited treatment options. This study aimed to define its genomic landscape, identify actionable targets (AT), and highlight the clinical value of molecular profiling—especially liquid biopsy (LB)—based on Gustave Roussy’s (GR) experience. In this retrospective analysis, 1844 patients from the U.S. and France underwent tissue biopsy (TB, n = 1733) and/or LB (n = 140), analyzed using the FoundationOne®CDx or FoundationOne® Liquid CDx assays both comprehensive genomic profiling assays for solid tumors covering 324 genes. Twenty-nine patients had paired TB/LB, and 44 LB patients formed the clinically annotated GR subgroup. HPV was detected in 86.6

PURPOSE:The purpose of this study was to evaluate baseline tumor burden from liquid biopsy (LB) and computed tomography (CT) as prognostic biomarkers and whether their combination refines stratification in metastatic solid cancers. MATERIALS AND METHODS:This retrospective cohort study included 1065 patients. Eligible patients underwent LB and chest-abdomen-pelvis CT examination at baseline. Radiologists outlined lesions on the largest axial slice, and total tumor volume (TTV) was approximated in three dimensions. LB Tumor fraction (TF) ≥ 10 % was considered high. To assess combined prognostic power of LB and TTV, patients were divided into three groups according to LB (circulating tumor deoxyribonucleic acid [ctDNA] detectability and TF) and each group was further divided into two subgroups using TTV thresholds determined by Youden's index. Overall survival (OS) analyses were performed using Cox proportional hazard models and Kaplan-Meier curves. RESULTS:A total of 560 patients (290 women and 270 men; median age, 61 years) with 31,314 annotated lesions were selected. The median OS was 11.28 months, and the median TTV was 96.68 cm3. The LB groups included patients with undetectable ctDNA (n = 102), patients with detectable ctDNA and low TF (n = 251), and patients with high TF (n = 207). Integrating TTV thresholds (18.7 cm3, 44.9 cm3, and 159.94 cm3) to LB groups significantly stratified the population on OS. Patients with undetectable ctDNA and TTV ≥ 18.7 cm3 had significantly shorter OS (median OS, 24.8 months) than those with TTV < 18.7 cm3 (median OS, > 35 months). CONCLUSION:Combining baseline CT tumor burden with LB could be a valuable prognostic tool for stratifying patients with metastatic solid cancer.

(Abstracted from Cancer 2024;130(19):3311–3320) Endometrial cancer (EC) has been increasing in incidence and mortality rates due to increased prevalence of risk factors such as obesity, metabolic syndrome, and diabetes. Many cases are treatable through a combination of methods, but up to 20% of cases are detected at an advanced stage, which has a grim prognosis.

Background Tumor fraction (TF) at liquid biopsy is a potential noninvasive marker for tumor burden, but validation is needed. Purpose To evaluate TF as a potential surrogate for tumor burden, assessed at contrast-enhanced CT across diverse metastatic cancers. Methods This retrospective monocentric study included patients with cancer and metastatic disease, with TF results and contemporaneous contrast-enhanced CT performed between January 2021 and January 2023. The total tumor volume (TTV), representing CT tumor burden, was calculated by adding all lesion volumes and was computed by using manually outlined annotations of each lesion on the largest surface of the axial slice. TF greater than 10% was considered high. A training-validation split was applied. Correlations between TF and TTV were assessed using regression models and Spearman correlation coefficients. Receiver operating characteristic curve analysis established the TTV cutoff. The metastatic site, histology type, and TTV were used to predict liquid biopsy contributory status. Results Among 1065 patients (median age, 62 years [IQR: 53, 70]; 537 female), 56 288 lesions were annotated, mostly in the lung (n = 20 334), lymph nodes (n = 11 651), and liver (n = 10 277). A total of 763 liquid biopsies were contributive, 254 were noncontributive, and 48 failed. The training and validation sets included 745 and 320 patients, respectively. TF helped predict TTV with the linear model (R2 = 0.17; ρ = 0.41; P < .001). The TTV and TF categories achieved an area under the receiver operating characteristic curve (AUC) of 0.74 (95% CI: 0.71, 0.78), with an optimal cutoff of 151 cm3 for TTV and a TF cutoff of 10%. The sensitivity was 57% (204 of 359) and the specificity was 80% (525 of 658). TTV helped predict contributory status, with an AUC of 0.71 (95% CI: 0.67, 0.76) and an optimal cutoff greater than 37 cm3. Liver lesion volumes were significantly associated with a contributory liquid biopsy in the validation cohort. Conclusion While correlated, TF at liquid biopsy did not accurately represent the TTV at CT. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Koh in this issue.

For patients with advanced stage non-small cell lung cancer (NSCLC), treatment strategies have changed significantly due to the introduction of targeted therapies and immunotherapy. In the last few years, we have seen an explosive growth of newly introduced targeted therapies in oncology and this development is expected to continue in the future. Besides primary targetable aberrations, emerging diagnostic biomarkers also include relevant co-occurring mutations and resistance mechanisms involved in disease progression, that have impact on optimal treatment management. To accommodate testing of pending biomarkers, it is necessary to establish routine large-panel next-generation sequencing (NGS) for all patients with advanced stage NSCLC. For cost-effectiveness and accessibility, it is recommended to implement predictive molecular testing using large-panel NGS in a dedicated, centralized expert laboratory within a regional oncology network. The central molecular testing center should host a regional Molecular Tumor Board and function as a hub for interpretation of rare and complex testing results and clinical decision-making.

PURPOSE With liquid biopsy's widespread adoption in oncology, an increased number of clonal hematopoiesis–associated mutations (CHm) have been identified in patients with solid tumors. However, its impact on patient outcomes remains unclear. This study aimed to analyze and describe CHm in a cohort of phase I patients. METHODS Retrospective data collection from medical records and molecular profiles (Foundation One Liquid CDx Assay) was performed before first study drug administration at the Drug Development Department of Gustave Roussy (France) within the STING trial (ClinicalTrials.gov identifier: NCT04932525 ). CHm prevalence was assessed using any and ≥1% variant allele frequency (VAF) in epigenetic modifier genes ( DNMT3A, TET2, and ASXL1). RESULTS From January 2021 to December 2022, 255 patients were enrolled in a phase I clinical trial. A total of 55% were male, with a median age of 62 years (24-86). Principal tumor locations were GI (27%) and genitourinary (21%). Overall, 104 patients (41%) had at least one CHm in liquid biopsy, with 55 patients (22%) having a VAF of ≥ 1%. The most frequent mutation was DNMT3A 73% at any VAF (n = 76) and 22% at 1% VAF (n = 23). Median progression-free survival (PFS) and overall survival were 3.8 months (m) for the CHm group versus 3.2 m for nonclonal hematopoiesis (CH; P = .08) and 18.26 m CHm versus 15.8 m non-CH ( P = .9), respectively. PFS increased in the CHm population treated with targeted therapy (hazard ratio, 0.6 [95% CI, 0.42 to 0.84]; P = .004). CONCLUSION CHm was commonly found in patients with solid tumors treated in phase I trials, with a prevalence of 41% in our cohort. The most frequently mutated gene was DNMT3A. The presence of CHm had no impact on the population of patients treated in the phase I trials.

Selecting patients for phase I cancer trials is crucial to ensure a sufficient life expectancy. Frail patients, better suited for palliative care, should not be exposed to new drugs with minimal benefit. Enrolling patients at high risk of early death can jeopardize the study. Our analysis of two large precision medicine studies used tumor fraction from ctDNA to develop a predictive model, demonstrating notable predictive accuracy and aiding in patient selection.

Next-generation sequencing (NGS) assays based on plasma cell-free DNA (cfDNA) are increasingly used for clinical trials inclusion. Their optimized limit of detection applied to a large number of genes leads to the identification of mutations not confirmed in tissue. It becomes essential to describe the characteristics and consequences of these liquid biopsy-only mutations . In the STING protocol (Gustave Roussy, NCT04932525), 542 patients with advanced solid cancer had cfDNA-based and tissue-based NGS analysis (performed by FoundationOne® Liquid CDx and FoundationOne CDx™, respectively). Mutations identified in the liquid biopsy but not in the paired tissue were considered as liquid biopsy-only mutations irrespective of their variant allelic frequency (VAF). Out of 542 patients, 281 (51.8%) harbored at least one liquid biopsy-only mutation . These patients were significantly older, and more heavily pretreated. Liquid biopsy-only mutations occurring in TP53 , and in DDR genes ( ATM , CHEK2, ATR, BRCA2, and BRCA1) accounted for 90.8% of all the mutations. The median VAF of these mutations was generally low (0.37% and 0.40% for TP53 and DDR genes respectively). The variant type repartition depended on the gene. Liquid biopsy-only mutations affected hotspot in TP53 codon 273, 125, 195, 176, 237 or 280 and ATM codon 2891 and 3008. In a subset of 37 patients, 75.0%, 53.5% and 83.3% of the liquid biopsy-only mutations occurring respectively in ATM , TP53, and CHEK2 were confirmed in the matching whole blood sample. Although liquid biopsy-only mutations makes the interpretation of liquid biopsy results more complex, they have distinct characteristics making them more easily identifiable.

Next-generation sequencing (NGS) allows sequencing of a high number of nucleotides in a short time frame at an affordable cost. While this technology has been widely implemented, there are no recommendations from scientific societies about its use in oncology practice. The European Society for Medical Oncology (ESMO) is proposing three levels of recommendations for the use of NGS. Based on the current evidence, ESMO recommends routine use of NGS on tumour samples in advanced non-squamous non-small-cell lung cancer (NSCLC), prostate cancers, ovarian cancers and cholangiocarcinoma. In these tumours, large multigene panels could be used if they add acceptable extra cost compared with small panels. In colon cancers, NGS could be an alternative to PCR. In addition, based on the KN158 trial and considering that patients with endometrial and small-cell lung cancers should have broad access to anti-programmed cell death 1 (anti-PD1) antibodies, it is recommended to test tumour mutational burden (TMB) in cervical cancers, well- and moderately-differentiated neuroendocrine tumours, salivary cancers, thyroid cancers and vulvar cancers, as TMB-high predicted response to pembrolizumab in these cancers. Outside the indications of multigene panels, and considering that the use of large panels of genes could lead to few clinically meaningful responders, ESMO acknowledges that a patient and a doctor could decide together to order a large panel of genes, pending no extra cost for the public health care system and if the patient is informed about the low likelihood of benefit. ESMO recommends that the use of off-label drugs matched to genomics is done only if an access programme and a procedure of decision has been developed at the national or regional level. Finally, ESMO recommends that clinical research centres develop multigene sequencing as a tool to screen patients eligible for clinical trials and to accelerate drug development, and prospectively capture the data that could further inform how to optimise the use of this technology.