Microsatellite instability (MSI) is a widely studied molecular signature, which is associated with long-term benefit in patients treated with immune checkpoint inhibitor therapy. This approach has been proven to be effective in the treatment of patients with MSI-positive colorectal cancer (CRC). Analysis of serial liquid biopsy samples allows to detect changes in the tumor in response to therapy. Typically, somatic mutations are used for tracing the dynamics of the tumor, and the assessment of DNA signatures such as MSI is not currently used for these purposes. Here, we describe a case of a MSI-positive CRC, who received nivolumab monotherapy. Sequential sampling of the patient’s plasma demonstrated an increase in MSI burden (bMSI), which was found to correlate with the increase of driver mutation burden one month after starting nivolumab, and hyperprogressive disease. Thus, analysis of bMSI in liquid biopsy via NGS may be a promising method for timely assessment of the treatment effectiveness received by patients with MSI-positive CRC.

INTRODUCTION:Immune checkpoint inhibitors are highly effective in treating various cancers. We analyzed the significance of the KRAS/STK11 co-mutation in relation to the efficacy of immune checkpoint inhibitors in pan-cancer patient cohort.METHODS:We analyzed data from open-access research: MSK-IMPACT (molecular profiling data from patients receiving systemic antitumor therapy) and MSK-TMB (molecular profiling data from patients receiving immune checkpoint inhibitors). In both studies, high throughput sequencing was used for molecular profiling.RESULTS:A total of 10,336 patients receiving antitumor therapy (MSK-IMPACT study) and 1661 patients receiving immune checkpoint inhibitors (MSK-TMB study) were included in the analysis. Co-mutation STK11/KRAS was found in 156 (1.5%) and 46 (2.8%) patients in the two studies, respectively. Most patients with the STK11/KRAS co-mutation had non-small cell lung cancer (83% and 85% in the two studies, respectively). Among non-small cell lung cancer patients, the STK11 mutation was associated with a worse outcome for patients receiving systemic antitumor therapy, but not immune checkpoint inhibition therapy (HR for OS 1.90 [95% CI 1.36-2.65] and 1.44 [95% CI 0.88-2.37]). Co-mutation STK11/KRAS was also not associated with patient outcome in any of the studies (HR for OS 0.93 [95% CI 0.56-1.52] and 1.09 [95% CI 0.54-2.19]). High tumor mutational burden was associated with better outcome in the cohort of patients receiving immune checkpoint inhibitors. An analogous analysis among patients in the pan-cancer cohort (excluding patients with non-small cell lung cancer) showed STK11 mutations and high tumor mutational burden have a predictive role for the efficacy of immune checkpoint inhibitors, but not STK11/KRAS co-mutation.CONCLUSIONS:Co-mutation STK11/KRAS is common among patients with non-small cell lung cancer and is not an independent predictive marker for the efficacy of immune checkpoint inhibitors. Further studies are required to clarify the role of STK11 mutations in immune checkpoint inhibitor treatment response.

Genomic profiling, or molecular profiling of the tumor, is becoming a key component of therapeutic decision making in clinical oncology, and is typically carried out via next generation sequencing. However, the interpretation of the results and evaluation of rationale for targeting the uncovered alterations is challenging and requires a deep understanding of cancer biology, genetics, genomics and oncology. Multidisciplinary molecular tumor boards represent a promising strategy in the facilitation of molecularly-informed therapeutic decisions, and usually consist of specialists with various fields of expertise. To effectively communicate the biological and clinical significance of genomic findings, as well as to make molecular tumor board discussions more productive, we developed and implemented evidence blocks into case discussions in our center. We found that this approach facilitated clinicians’ understanding of the results of genomic profiling, and resulted in shorter yet more efficient case discussions within the molecular tumor board. Here, we discuss our experience with evidence blocks and how their implementation influenced the molecular tumor board practice.

Analysis of serial liquid biopsy (LB) samples has been found to be a promising approach for the monitoring of tumor dynamics in the course of therapy for patients with colorectal cancer (CRC). Currently, somatic mutations are used for tracing the dynamics of the tumor via LB. However, the analysis of the dynamic changes in the molecular signatures such as microsatellite instability (MSI) is not currently used. We hypothesized that changes in blood MSI burden (bMSI) could be registered using serial LB sampling in the course of immune checkpoint inhibitors (ICI), and that its changes could potentially correlate with treatment outcomes. We report the preliminary findings of the observational trial launched to study (NCT06414304) the dynamics of bMSI in 9 MSI-positive CRC patients receiving ICI. NGS-based MSI testing was performed on both pre-treatment FFPE and serial LB samples. For patients who had detectable bMSI burden in any of the LB samples (n = 8, 89%), median bMSI was 1.4% (range, 0.01-40%). Among patients with detectable MSI in available FFPE samples, median MSI burden was 29.3% (range, 10-40%). bMSI detected in baseline LB and FFPE samples were positively correlated (Pearson's R 0.47). Maximal variant allele frequencies of driver mutations observed in LB were also positively correlated with bMSI burden (Pearson's R 0.7). Patients who had clinical benefit had undetectable bMSI burden at follow-up. Our results provide the rationale for further validation of bMSI as a predictive biomarker of ICI in MSI-positive patients.

Background:Testing for homologous recombination deficiency (HRD) mutations is pivotal to assess individual risk, to proact preventive measures in healthy carriers and to tailor treatments for cancer patients. Increasing prominence of poly(ADP-ribose) polymerase (PARP) inhibitors with remarkable impact on molecular-selected patient survival across diverse nosologies, ingrains testing for BRCA genes and beyond in clinical practice. Nevertheless, testing strategies remain a question of debate. While several pathogenic BRCA1/2 gene variants have been described as founder pathogenic mutations frequently found in patients from Russia, other homologous recombination repair (HRR) genes have not been sufficiently explored. In this study, we present real-world data of routine HRR gene testing in Russia. Methods:We evaluated clinical and sequencing data from cancer patients who had germline/somatic next-generation sequencing (NGS) HRR gene testing in Russia (BRCA1/2/ATM/CHEK2, or 15 HRR genes). The primary objectives of this study were to evaluate the frequency of BRCA1/2 and non-BRCA gene mutations in real-world unselected patients from Russia, and to determine whether testing beyond BRCA1/2 is feasible. Results:Data of 2,032 patients were collected from February 2021 to February 2023. Most had breast (n = 715, 35.2%), ovarian (n = 259, 12.7%), pancreatic (n = 85, 4.2%), or prostate cancer (n = 58, 2.9%). We observed 586 variants of uncertain significance (VUS) and 372 deleterious variants (DVs) across 487 patients, with 17.6% HRR-mutation positivity. HRR testing identified 120 (11.8%) BRCA1/2-positive, and 172 (16.9%) HRR-positive patients. With 51 DVs identified in 242 formalin-fixed paraffin-embedded (FFPE), testing for variant origin clarification was required in one case (0.4%). Most BRCA1/2 germline variants were DV (121 DVs, 26 VUS); in non-BRCA1/2 genes, VUS were ubiquitous (53 DVs, 132 VUS). In silico prediction identified additional 4.9% HRR and 1.2% BRCA1/2/ATM/CHEK2 mutation patients. Conclusions:Our study represents one of the first reports about the incidence of DV and VUS in HRR genes, including genes beyond BRCA1/2, identified in cancer patients from Russia, assessed by NGS. In silico predictions of the observed HRR gene variants suggest that non-BRCA gene testing is likely to result in higher frequency of patients who are candidates for PARP inhibitor therapy. Continuing sequencing efforts should clarify interpretation of frequently observed non-BRCA VUS.

Colorectal cancer (CRC) represents a molecularly heterogeneous disease and one of the most frequent causes of cancer-related death worldwide. The traditional classification of CRC is based on pathomorphological and molecular characteristics of tumor cells (mucinous, ring-cell carcinomas, etc. ), analysis of mechanisms of carcinogenesis involved (chromosomal instability, microsatellite instability, CpG island methylator phenotype) and mutational statuses of commonly altered genes (KRAS, NRAS, BRAF, APC, etc. ), as well as expression signatures (CMS 1-4). It is also suggested that the tumor microenvironment is a key player in tumor progression and metastasis in CRC. According to the latest data, the immune microenvironment can also be predictive of the response to immune checkpoint inhibitors. In this review, we highlight how the immune environment influences CRC prognosis and sensitivity to systemic therapy.

Background The widespread use of next-generation sequencing in clinical practice has contributed to the accumulation of a large number of genomic findings associated with targeted therapy; therefore, the problem of ranking the detected findings has become acute. The European Society for Medical Oncology Scale of Clinical Actionability of molecular Targets (ESCAT) system was designed by the European Society for Medical Oncology to rank biomarkers into levels of evidence that reflect their potency and clinical significance based on published clinical data. However, the ESCAT system remains imperfect, as it is based on a subjective assessment of the levels of evidence. Objective The objective of this study was to determine whether the ranking of LOE for biomarker-drug pairs based on the ESCAT system is dependent on the human factor, and to uncover potential issues associated with the use of the framework. Methods To evaluate the inter-rater agreement, we created a dataset of a total of 154 biomarker-drug pairs for 18 unique tumor types. We aimed to include biomarker-drug pairs that could be considered standard of care as well as less common and under investigated pairs. Fourteen precision oncology experts were invited to assign an ESCAT level of evidence for biomarker-drug pairs. Statistical analysis was carried out using Cohen's kappa and the Kolmogorov-Smirnov test. Results The inter-rater agreement was low with some exceptions, and significant deviations from the consensus level of evidence were observed. For biomarker-drug associations, the deviations from the consensus were observed for more than 50% of the contributors' rankings. The most agreement between the contributors was observed for lung adenocarcinoma (p < 0.005), while the most disagreement was observed for esophageal cancer (p < 0.01) biomarker-drug pairs in our dataset. Conclusions This study demonstrates noteworthy discordances between the precision oncology experts and may provide the directions for future developments in modifying the ESCAT framework and the overall applicability of the results of genomic profiling into clinical practice.

Microsatellite instability (MSI) is an important biomarker in cancer. While routine methods can detect MSI in certain tumor types, in other tumor types the results may be incorrect due to differences in the MSI loci pattern. Here, we report the case of a patient with pancreatic adenocarcinoma, with confirmed MSI by two independent next-generation sequencing tests, but not by routine methods, who had progression on pembrolizumab. Comparison of the patient's MSI loci patterns with MSI+ colorectal adenocarcinoma samples showed a lower fraction of unstable loci, low resolution of a second peak in the repeat length spectrum of unstable short tandem repeats in the patient's sample, and a lower length of indels (3.7 vs 4.5 base pairs, p < 0.01).

Molecularly-matched therapy (MMT) is associated with increased response rates and in some cases with improved survival. Next generation sequencing (NGS) - based multigene panels offer a wide range of analyzed markers. There is a need to optimize comprehensive profiling and find the most relevant molecular targets according to tumor type. Retrospective analysis of NGS reports and clinical data of patients with advanced gastrointestinal tumors was performed. The frequency of detected molecular alterations in each cancer type, the frequency of MMT recommendation were assessed. Efficacy was estimated using progression-free survival (PFS) ratio (PFS2/PFS1). Between 2019 and 2023, tumor samples from 107 patients with gastrointestinal tumors were analyzed using NGS-based panels (colorectal cancer (CRC) - 64 patients (59%), pancreatic cancer (PCa) - 21 (20%), cholangiocellular cancer (CCC) - 12 (11%), gastric cancer (GC) - 11 (10%). Median age was 58 years, median number of lines before analysis - 2. MMT after NGS was administered to 17 patients (16%). Of these patients 6 samples were assesed as ESCAT I tier (35%), 2 (12%) - ESCAT IIB, 2 (12%) - ESCAT IIIA, 7 (51%) - ESCAT IIIB. PFS2/1 ratio≥1,3 was reached in 10 patients (59%). In the cohort of patients who have not been prescribed MMT, the PFS ratio was available for 42 patients, among whom 11 patients (26%) achieved PFS1/2 ≥1,3 (p=0,005). MMT was the only favorable predictor of PFS2/1 ≥1.3 (HR 0.13; 95% CI 0.03 - 0.50, p=0.003) in univariate analysis. Median overall survival in the MMT and non-MMT groups was 6 and 5 months, respectively (HR=2.07; 95% CI 1.01 - 4.26).Table: 164PVariablesUnivariate analysisHR (95% CI)p valueAge, years ≥60 <601,00 0,80 (0,21 -2,91)0,72Number of lines before analysis, ≤1 ≥21,00 0,67 (0,16 - 2,86)0,59Sex, m f1,60 (0,45 - 5,70) 1,000,47Molecular tumor board Yes No1,00 0,61 (0,13 - 2,85)0,53RAS RASwt RASmut1,00 (0,28 - 3,61) 1,001,00MMT Yes No1,00 0,13 (0,03 - 0,50)0,003 Open table in a new tab . MMT may potentially have advantages over non-MMT in advanced gastrointestinal cancers when standard therapy options are limited. In order to optimize testing in routine practice, it is necessary to create more limited panels for profiling according to each tumor type.

e15163 Background: Comprehensive molecular profiling (CMP) via next generation sequencing (NGS) is currently applied in clinical practice and has enabled the detection of biomarkers of response to targeted treatment. Given the lack of the data about optimal range of analyzed alterations, the clinical usefulness of CMP has not been established. To address the challenges in incorporating genomics in treatment of oncology patients, we conducted a retrospective study. Methods: Preliminary analysis of NGS reports and clinical data of patients with advanced solid tumors was performed. CMP was conducted in 261 cancer patients (non-small cell lung cancer - 30,6%, colorectal cancer - 24,8%, pancreatic cancer - 7,4%, breast cancer- 6,2%; 59,3% were female, median number of prior systemic treatment lines was 2 (0-12)). In the present study, tumor molecular profile analysis was performed using 160 - 400 gene NGS panels, containing the majority of clinically significant genes for cancer treatment selection. We assessed the percentage of patients who were recommended to receive molecularly-matched therapy (MMT) after CMP, immunotherapy (IT) distribution of recommended therapies according to ESCAT tiers, median progression-free survival (PFS) – ratio ( = PFS after CMP / PFS before CMP, PFS2/PFS1), median PFS2. Results: MMT after CMP was recommended for 55 (21,1%) patients. ESCAT tiers could be assessed in 48 MMT patients (87%). For 31% of patients, administered therapy was considered as ESCAT I tier recommendation (data on mPFS2/1, mPFS2 not available). ESCAT tiers II, III, IV and IT administration were considered in 31, 8, 8 and 22% of patients respectively (detailed data is presented in Table 1). Most commonly altered genes were TP53 (53%), RAS (29%), APC (18%), CDKN2A/B (16%), PIK3CA(14%), NF1 (10%), BRCA1/2 (9%). Positive predictive factors for MMT after CMP were MSI-high status (HR 0,13, 95% CI 0,03 - 0,67), presence of EGFR alteration (HR 0,32, 95% CI 0,12 - 0,86). Presence of RAS mutation was considered a negative predictive factor (HR 2,78, 1,07 - 7,26). Conclusions: Available NGS panels offer a wide range of analyzed alterations that are not feasible in clinical practice. Most of the alterations that can cause impact on treatment plan can be detected with other methods than NGS. Further studies are needed to determine optimal range of alterations depending on tumor site. [Table: see text]

Microsatellite instability (MSI) is a powerful predictor for the efficacy of immune checkpoint inhibitor (ICI) therapy across tumor types. Although conventional MSI testing strategies are widely used, NGS represents a promising tool for MSI detection. We have developed and validated the NGS test system for MSI detection in solid tumors. The following sample types were selected for validation of our test system: G1 - archive FFPE tumor samples collected from patients with known MSI status; G2 - archive paired (FFPE/ctDNA) samples collected from patients with tumors where MSI is uncommon (<1%); G3 - paired (FFPE/ctDNA) MSI+ samples. All FFPE samples were tested using the gold standard (5-loci PCR, 4-antibody IHC). Samples were considered MSI+ if PCR or IHC were positive; MSI- when both were negative. Detection of MSI was performed using k-mer distributions of 28 loci. A total of 123 samples for 109 patients were analyzed - 77 (62.6%) FFPE, 46 (37.4%) ctDNA; 6 patients had paired samples. A total of 30 (FFPE, 83% CRC), 72 (41 FFPE, 31 ctDNA; 62.3% NSCLC) and 21 (6 patients; 6 FFPE, 15 ctDNA; 66.7% CRC) were selected for G1, G2 and G3, respectively. Rate of agreement (κ) between NGS and gold standard in G1 was 0.8 (95% CI, 0.58-1) [κ for NGS/PCR 0.93 (95% CI, 0.8-1)], and 1 in G3. In G2, 100% of samples were MSS following NGS. In G3, for all 6 samples there were no disagreements between NGS and gold standard. Across all analyzed FFPE samples, κ between NGS and gold standard was 0.9 (95% CI 0.88-0.92). When comparing results of PCR and IHC (FFPE samples), low concordance was noted (κ=0.5, 95% CI, 0.22-0.78). High concordance was observed between PCR and NGS (κ=0.94, 95% CI, 0.83-1). Concordance of IHC and NGS was low (κ=0.55, 95% CI, 0.28-0.83). Sensitivity / specificity of NGS vs IHC in detecting MSI were 76.2% / 80%. Sensitivity / specificity of NGS vs PCR were 95.5% / 100%. Sensitivity / specificity of NGS in detecting MSI using ctDNA vs FFPE were 100% / 100%. Low concordance was observed between IHC and PCR for MSI detection (κ=0.5, 95% CI, 0.22-0.78). Concordance of PCR and NGS was high (κ=0.94, 95% CI, 0.83-1); concordance between IHC and NGS was lower (κ=0.55, 95% CI, 0.28-0.83). Sensitivity of MSI detection using ctDNA was 100%.

Введение: Появление в клинической практике возможности комплексного молекулярного профилирование (КМП) и регистрация новых таргетных препаратов привело к развитию прецизионного подхода в онкологии. Задачей работы являлась оценка опыта применения КМП у пациентов с распространенными опухолями желудочно-кишечного тракта (ЖКТ) в Российской Федерации. Материалы и методы: Проведен ретроспективный анализ клинических данных и отчетов КМП пациентов с опухолями ЖКТ. Цель исследования — оценка доли пациентов, которые получают молекулярно-направленную терапию (МНТ) после КМП, а также определение клинической пользы, которая оценивалась как длительность ответа на МНТ ≥ 6 месяцев. Также проведена оценка распределения альтераций по шкале ESCAT в зависимости от нозологии, частота объективных ответов и ОВ при назначении МНТ или стандарта терапии. Результаты: С марта 2018 по июнь 2023 гг. КМП было проведено 147 пациентам с опухолями ЖКТ (КРР — 64 %, РПЖ — 14,3 %, РЖ- 12,2 %, ХЦР — 9,5 %). Средний возраст составил 58 лет, лица мужского и женского пола были представлены в равной степени, среднее число линий до КМП — 2. МНТ проведена 19 (13 %) пациентам, клиническая польза зафиксирована у 6 больных (4 %). Одногодичная ОВ: 47,4 % против 29,5 % в группе МНТ и стандарта терапии (ОР = 2,147, 95 % ДИ 1,075–4,289, p = 0,020). КМП позволило выявить 12,1 % пациентов с максимальным уровнем ESCAT — I, 1,3 % — ESCAT II, 31,5 % — ESCAT III и 16,8 % — ESCAT IV. У 38,2 % пациентов обнаруженные при КМП альтерации не являлись предиктивными. За пределами ESCAT I, II клиническая польза была достигнута лишь у двух пациентов (1,3 %). Выводы: Несмотря на увеличение частоты объективных ответов и выявленные различия в ОВ, проведение доступных вариантов КМП приводит к смене тактики лечения у небольшой доли пациентов. Лишь 4 % пациентов в нашем исследовании получили клиническую пользу от МНТ, что соответствует данным литературы.

Article Tools REVIEW ARTICLES Diagnostics Article Tools OPTIONS & TOOLS Export Citation Track Citation Add To Favorites Rights & Permissions COMPANION ARTICLES No companion articles ARTICLE CITATION DOI: 10.1200/PO.23.00010 JCO Precision Oncology no. 7 (2023) e2300010. Published online June 14, 2023. PMID: 37315263 Microsatellite Instability Detection: The Current Standards, Limitations, and Misinterpretations Valentina Yakushina , PhD1,2xValentina YakushinaSearch for articles by this author; Alexandra Kavun , MSc1xAlexandra KavunSearch for articles by this author; Egor Veselovsky, MSc1,3xEgor VeselovskySearch for articles by this author; Tatiana Grigoreva , MSc1,4xTatiana GrigorevaSearch for articles by this author; Ekaterina Belova , PhD1,5xEkaterina BelovaSearch for articles by this author; Alexandra Lebedeva , MSc1xAlexandra LebedevaSearch for articles by this author; Vladislav Mileyko , MSc1xVladislav MileykoSearch for articles by this author; and Maxim Ivanov , PhD1,6xMaxim IvanovSearch for articles by this author Show More 1OncoAtlas LLC, Moscow, Russian Federation2Laboratory of Epigenetics, Research Centre for Medical Genetics, Moscow, Russian Federation3Department of Evolutionary Genetics of Development, Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, Moscow, Russian Federation4Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation5Lomonosov Moscow State University, Moscow, Russian Federation6Moscow Institute of Physics and Technology, Moscow, Russian Federation https://doi.org/10.1200/PO.23.00010 First Page Full Text PDF Figures and Tables © 2023 by American Society of Clinical OncologyCONTEXTKey ObjectiveAccurate microsatellite instability (MSI) assessment is critical for Lynch syndrome diagnostics, prognosis of disease progression, and success of chemotherapy and immunotherapy. In immunotherapy, false-positive MSI testing prevents putative responding patients from receiving effective treatment, and false-negative MSI testing leads to the prescription of ineffective therapy with its adverse effects.Knowledge GeneratedThis article provides the main advantages and limitations of the standard MSI testing methods and novel approaches in clinical practice, assesses possible sources of errors, discusses best practices and guidelines, and highlights the unsolved questions that remain sources of incorrect interpretation.RelevanceAmong novel approaches, next-generation sequencing (NGS) is considered one of the most promising; its advantages include high accuracy, an expanded spectrum of microsatellites analyzed, and simultaneous assessment of a comprehensive spectrum of clinically significant markers. In liquid biopsy, NGS-based approaches demonstrate outstanding results.SUPPORTSupported by the Russian Science Foundation (project No. 22-75-10154; https://rscf.ru/project/22-75-10154/).AUTHOR CONTRIBUTIONSConception and design: Valentina Yakushina, Vladislav Mileyko, Maxim IvanovData analysis and interpretation: Alexandra Kavun, Egor Veselovsky, Tatiana Grigoreva, Ekaterina Belova, Alexandra LebedevaManuscript writing: All authorsFinal approval of manuscript: All authorsAccountable for all aspects of the work: All authorsAUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTERESTThe following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated unless otherwise noted. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/po/author-center.Open Payments is a public database containing information reported by companies about payments made to US-licensed physicians (Open Payments).Valentina YakushinaEmployment: Atlas OncodiagnosticsAlexandra KavunEmployment: OncoAtlas LLCEgor VeselovskyEmployment: OncoAtlas LLCTatiana GrigorevaEmployment: OncoAtlas LLCEkaterina BelovaEmployment: OncoAtlas LLCAlexandra LebedevaEmployment: OncoAtlas LLCVladislav MileykoEmployment: OncoAtlas LLCLeadership: OncoAtlas LLCStock and Other Ownership Interests: OncoAtlasResearch Funding: I-pharmMaxim IvanovEmployment: OncoAtlas LLCNo other potential conflicts of interest were reported.

Colorectal cancer (CRC) is currently one of the most common tumor types diagnosed worldwide. In the early stages, the disease responds well to surgical and chemotherapeutic treatment, but in the later stages when therapeutic options are exhausted, comprehensive genomic profiling can guide further treatment decisions. We present the case of a 46-year-old man of Ashkenazi Jewish ancestry who was diagnosed with KRAS-mutated metastatic colorectal cancer. After surgery and progression on standard FOLFOX/FOLFIRI + bevacizumab therapy, as well as on Trifluridine/Tipiracil, comprehensive genomic profiling was performed with the hope of expanding therapeutic options. Following comprehensive tumor molecular profiling via NGS, a discussion of the case was discussed at the local molecular tumor board in order to determine further treatment strategy. An activating variant of KRAS and PIK3CA, FLT3 and SRC amplification and damaging TP53 and APC variants were discarded by MTB as potential targetable biomarkers. The BRCA2 p.S1415fs*4 founder frameshift variant was of interest and the patient was included in the clinical trial investigating the efficacy of a PARP inhibitor talazoparib. Unfortunately, the disease progression was detected within one month of talazoparib treatment and the patient died during the 8th cycle of FOLFIRI + bevacizumab therapy rechallenge.