Novel ERBB2 Variant Potentially Associated with Resistance against Anti-HER2 Monoclonal Antibody-Based Therapy in ERBB2-Amplified Metastatic Colorectal Cancer.

PURPOSE: HER2-targeted therapies in ERBB2-amplified metastatic colorectal cancer (mCRC) are effective; however, a notable portion of patients do not respond to treatment, and secondary resistance occurs in most patients receiving these treatments. The purpose of this study was to investigate determinants of treatment efficacy and resistance in patients with ERBB2-amplified mCRC who received HER2-targeted therapy by analyzing multiomics data. EXPERIMENTAL DESIGN: We investigated genomic data from a nationwide large cancer genomic screening project, the SCRUM-Japan project. We analyzed paired genome and transcriptome data of tissue and genomic data of ctDNA collected pre- and postprogression in patients enrolled in the related trial, TRIUMPH, in ERBB2-amplified mCRC. RESULTS: In 155 patients with ERBB2-amplified solid tumors who received HER2-targeted therapy based on the SCRUM-Japan project, the objective response rate was 50%, 51%, and 35% in ERBB2 wild-type, variant of unknown significance, and pathogenic variant groups, respectively. In the paired genome and transcriptome data analyses in TRIUMPH, we identified the novel splicing-associated variant c.644-66_-2del in one of the 11 patients with paired whole-exome sequencing and whole-transcriptome sequencing data sets, which lacks the binding domain of pertuzumab, in progressed metastatic tumor as a variant with potential pathogenicity. The time-course ctDNA analysis detected c.644-66_-2del as an acquired variant. CONCLUSIONS: This study highlighted the importance of ERBB2 genomic status when evaluating the efficacy of HER2-targeted therapies in ERBB2-amplified mCRC. The identification of a novel splicing-associated variant may provide insights into potential mechanisms of treatment resistance. Furthermore, we demonstrated the utility of ctDNA to follow the acquired genomic status of mCRC tumors.

The SCRUM-MONSTAR Cancer-Omics Ecosystem: Striving for a Quantum Leap in Precision Medicine.

The SCRUM-Japan MONSTAR-SCREEN consortium is a nationwide molecular profiling project employing artificial intelligence-driven multiomics analyses for patients with advanced malignancies, aiming to develop novel therapeutics and diagnostics and deliver effective drugs to patients. Concurrently, studies assessing molecular residual disease-based precision medicine for resectable solid tumors, including CIRCULATE-Japan, are ongoing. The substantial data generated by these platforms are stored within a state-of-the-art supercomputing infrastructure, VAPOR CONE. Since 2015, our project has registered over 24,000 patients as of December 2023. Among 16,144 patients with advanced solid tumors enrolled in MONSTAR-SCREEN projects, 5.0% have participated in matched clinical trials, demonstrating a 29.2% objective response rate and 14.8-month median survival (95% CI, 13.4-16.3) for patients treated in the matched clinical trials. Notably, patients who received matched therapy demonstrated significantly prolonged overall survival compared with those who did not (hazard ratio 0.77; 95% confidence interval, 0.71-0.83). Significance: Our nationwide molecular profiling initiative played pivotal roles in facilitating the enrollment of patients with advanced solid tumors into matched clinical trials and highlighted the substantial survival benefits of patients treated with matched therapy. We aim to facilitate an industry-academia data-sharing infrastructure ecosystem, fostering new drug discovery paradigms and precision medicine.

Genomic Landscape of Circulating Tumor DNA in Patients With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor-2-Negative Metastatic Breast Cancer Treated With Abemaciclib: Data From the SCRUM-Japan Cancer Genome Screening Project.

PURPOSE: To understand the mutational landscape of circulating tumor DNA (ctDNA) and tumor tissue of patients with hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) metastatic breast cancer (MBC) treated with abemaciclib + endocrine therapy (ET). METHODS: Blood samples for ctDNA and/or tissue samples were collected from abemaciclib-treated patients with HR+/HER2- MBC enrolled in the SCRUM-Japan MONSTAR-SCREEN project. Blood samples were collected before abemaciclib initiation (baseline) and at disease progression/abemaciclib discontinuation (post abemaciclib treatment). Clinical and genomic characteristics including neoplastic burden (measured by shedding rate and maximum variant allele frequency [VAF]) were assessed at baseline. Genomic alterations in ctDNA were compared in paired baseline and post abemaciclib treatment samples. RESULTS: All patients (N = 97) were female (median age, 57 years [IQR, 50-67]). In baseline ctDNA (n = 77), PIK3CA (37%), TP53 (28%), ESR1 (16%), and GATA3 (11%) were the most frequently mutated genes. Baseline tissue samples (n = 79) showed similar alteration frequencies. Among patients with baseline ctDNA data, 30% had received previous ET. ESR1 alteration frequency (35% v 8%; P < .01), median shedding rate (3 v 2), and maximum somatic VAF (4 v 0.8; both P < .05) were significantly higher in ctDNA from patients with previous ET than those without previous ET. In paired ctDNA samples (n = 33), PIK3CA and ESR1 alteration frequencies were higher after abemaciclib treatment than at baseline, though not statistically significant. Among the post-treatment alterations, those newly acquired were detected most frequently in FGF3/4/19 (18%); PIK3CA, TP53, CCND1, and RB1 (all 15%); and ESR1 (12%). CONCLUSION: We summarized the ctDNA and cancer tissue mutational landscape, including overall neoplastic burden and PIK3CA and ESR1 hotspot mutations in abemaciclib-treated patients with HR+/HER2- MBC. The data provide insights that could help optimize treatment strategies in this population.

Whole-transcriptome sequencing in advanced gastric or gastroesophageal cancer: A deep dive into its clinical potential.

Advanced gastric and gastroesophageal junction cancers (GC/GEJCs) harbor diverse molecular signatures, highlighting the need for intricate evaluations to identify potential therapeutic targets. Although whole-transcriptome sequencing (WTS) has emerged as a useful tool for understanding these molecular intricacies, its clinical implications have yet to be fully elucidated. This study evaluated the correlation between immunohistochemistry (IHC) and WTS, compared their clinical significance, and identified potential therapeutic targets undetectable through IHC alone. We enrolled 140 patients with advanced GC/GEJC and assessed them using IHC for six pivotal biomarkers: claudin-18 (CLDN18), human epidermal growth factor receptor 2 (HER2), multiple receptor tyrosine kinases (RTKs), and programmed death ligand 1 (PD-L1). Concurrently, WTS was employed as part of the analyses in MONSTAR-SCREEN-2, a multicenter multiomics study. IHC analysis revealed 16.4% HER2, 39.3% CLDN18 (2+/3 + ≥75%), and 15.8% PD-L1 (combined positive score ≥ 10) positivity, among other molecular markers. Significant correlations were observed between IHC and WTS for all six pivotal biomarkers. Among nineteen HER2 IHC-positive patients treated with anti-HER2 therapeutics, ERBB2 status in WTS was significantly associated with progression-free survival (ERBB2-high vs. -low: median 9.0 vs. 5.6 months, log-rank p = 0.046). IHC-based molecular profiling revealed significantly high expression of CLDN18 in RTK-negative patients, with 78.4% positive for either CLDN18 or PD-L1. Additionally, WTS revealed elevated expression of pivotal biomarkers in patients displaying negative targetable biomarkers via IHC. Our findings highlighted the significant correlation between IHC and WTS, reinforcing the clinical utility of WTS. A subset with IHC-negative but WTS-positive status may benefit from specific biomarker-targeted therapies.

A Learning Program for Treatment Recommendations by Molecular Tumor Boards and Artificial Intelligence.

Importance: Substantial heterogeneity exists in treatment recommendations across molecular tumor boards (MTBs), especially for biomarkers with low evidence levels; therefore, the learning program is essential. Objective: To determine whether a learning program sharing treatment recommendations for biomarkers with low evidence levels contributes to the standardization of MTBs and to investigate the efficacy of an artificial intelligence (AI)-based annotation system. Design, Setting, and Participants: This prospective quality improvement study used 50 simulated cases to assess concordance of treatment recommendations between a central committee and participants. Forty-seven participants applied from April 7 to May 13, 2021. Fifty simulated cases were randomly divided into prelearning and postlearning evaluation groups to assess similar concordance based on previous investigations. Participants included MTBs at hub hospitals, treating physicians at core hospitals, and AI systems. Each participant made treatment recommendations for each prelearning case from registration to June 30, 2021; participated in the learning program on July 18, 2021; and made treatment recommendations for each postlearning case from August 3 to September 30, 2021. Data were analyzed from September 2 to December 10, 2021. Exposures: The learning program shared the methodology of making appropriate treatment recommendations, especially for biomarkers with low evidence levels. Main Outcomes and Measures: The primary end point was the proportion of MTBs that met prespecified accreditation criteria for postlearning evaluations (approximately 90% concordance with high evidence levels and approximately 40% with low evidence levels). Key secondary end points were chronological enhancements in the concordance of treatment recommendations on postlearning evaluations from prelearning evaluations. Concordance of treatment recommendations by an AI system was an exploratory end point. Results: Of the 47 participants who applied, 42 were eligible. The accreditation rate of the MTBs was 55.6% (95% CI, 35.3%-74.5%; P < .001). Concordance in MTBs increased from 58.7% (95% CI, 52.8%-64.4%) to 67.9% (95% CI, 61.0%-74.1%) (odds ratio, 1.40 [95% CI, 1.06-1.86]; P = .02). In postlearning evaluations, the concordance of treatment recommendations by the AI system was significantly higher than that of MTBs (88.0% [95% CI, 68.7%-96.1%]; P = .03). Conclusions and Relevance: The findings of this quality improvement study suggest that use of a learning program improved the concordance of treatment recommendations provided by MTBs to central ones. Treatment recommendations made by an AI system showed higher concordance than that for MTBs, indicating the potential clinical utility of the AI system.

Concordance Between Recommendations From Multidisciplinary Molecular Tumor Boards and Central Consensus for Cancer Treatment in Japan.

Importance: Quality assurance of molecular tumor boards (MTBs) is crucial in cancer genome medicine. Objective: To evaluate the concordance of recommendations by MTBs and centrally developed consensus treatment recommendations at all 12 leading institutions for cancer genomic medicine in Japan using 50 simulated cases. Design, Setting, and Participants: This was a prospective quality improvement study of 50 simulated cancer cases. Molecular tumor boards from 12 core hospitals independently recommended treatment for 50 cases blinded to the centrally developed consensus treatment recommendations. The study's central committee consisted of representatives from all 12 core hospitals in Japan who selected the 50 simulated cases from The Cancer Genome Atlas database, including frequently observed genomic alterations. The central committee recommended centrally developed consensus treatment. The concordance rate for genomically matched treatments between MTBs and centrally developed consensus treatment recommendations was evaluated. Data analysis was conducted from January 22 to March 3, 2021. Exposures: Simulated cases of cancer. Main Outcomes and Measures: The primary outcome was concordance, defined as the proportion of recommendations by MTBs concordant with centrally developed consensus treatment recommendations. A mixed-effects logistic regression model, adjusted for institutes as a random intercept, was applied. High evidence levels were defined as established biomarkers for which the treatment was ready for routine use in clinical practice, and low evidence levels were defined as biomarkers for genomically matched treatment that were under investigation. Results: The Clinical Practice Guidance for Next-Generation Sequencing in Cancer Diagnosis and Treatment (edition 2.1) was used for evidence-level definition. The mean concordance between MTBs and centrally developed consensus treatment recommendations was 62% (95% CI, 57%-65%). Each MTB concordance varied from 48% to 86%. The concordance rate was higher in the subset of patients with colorectal cancer (100%; 95% CI, 94.0%-100%), ROS1 fusion (100%; 95% CI, 85.5%-100%), and high evidence level A/R (A: 88%; 95% CI, 81.8%-93.0%; R:100%; 95% CI, 92.6%-100%). Conversely, the concordance rate was lower in cases of cervical cancer (11%; 95% CI, 3.1%-26.1%), TP53 mutation (16%; 95% CI, 12.5%-19.9%), and low evidence level C/D/E (C: 30%; 95% CI, 24.7%-35.9%; D: 25%; 95% CI, 5.5%-57.2%; and E: 18%; 95% CI, 13.8%-23.0%). Multivariate analysis showed that evidence level (high [A/R] vs low [C/D/E]: odds ratio, 4.4; 95% CI, 1.8-10.8) and TP53 alteration (yes vs no: odds ratio, 0.06; 95% CI, 0.03-0.10) were significantly associated with concordance. Conclusions and Relevance: The findings of this study suggest that genomically matched treatment recommendations differ among MTBs, particularly in genomic alterations with low evidence levels wherein treatment is being investigated. Sharing information on matched therapy for low evidence levels may be needed to improve the quality of MTBs.

Chronological improvement in precision oncology implementation in Japan.

In Japan, comprehensive genomic profiling (CGP) tests for refractory cancer patients have been approved since June 2019, under the requirement that all cases undergoing CGP tests are annotated by the molecular tumor board (MTB) at each government-designated hospital. To investigate improvement in precision oncology, we evaluated and compared the proportion of cases receiving matched treatments according to CGP results and those recommended to receive genetic counseling at all core hospitals between the first period (11 hospitals, June 2019 to January 2020) and second period (12 hospitals, February 2020 to January 2021). A total of 754 and 2294 cases underwent CGP tests at core hospitals in the first and second periods, respectively; 28 (3.7%) and 176 (7.7%) patients received matched treatments (p < 0.001). Additionally, 25 (3.3%) and 237 (10.3%) cases were recommended to receive genetic counseling in the first and second periods, respectively (p < 0.001). The proportion was associated with the type of CGP test: tumor-only (N = 2391) vs. tumor-normal paired (N = 657) analysis (10.0% vs. 3.5%). These results suggest that recommendations regarding available clinical trials in networked MTBs might contribute to increasing the numbers of matched treatments, and that tumor-normal paired rather than tumor-only tests can increase the efficiency of patient referrals for genetic counseling.

Expert panel consensus recommendations on the use of circulating tumor DNA assays for patients with advanced solid tumors.

Comprehensive genomic profiling is increasingly used to facilitate precision oncology based on molecular stratification. In addition to conventional tissue comprehensive genomic profiling, comprehensive genomic profiling of circulating tumor DNA has become widely utilized in cancer care owing on its advantages, including less invasiveness, rapid turnaround time, and capturing heterogeneity. However, circulating tumor DNA comprehensive genomic profiling has some limitations, mainly false negatives due to low levels of plasma circulating tumor deoxyribonucleic acid and false positives caused by clonal hematopoiesis. Nevertheless, no guidelines and recommendations fully address these issues. Here, an expert panel committee involving representatives from 12 Designated Core Hospitals for Cancer Genomic Medicine in Japan was organized to develop expert consensus recommendations for the use of circulating tumor deoxyribonucleic acid-based comprehensive genomic profiling. The aim was to generate guidelines for clinicians and allied healthcare professionals on the optimal use of the circulating tumor DNA assays in advanced solid tumors and to aid the design of future clinical trials that utilize and develop circulating tumor DNA assays to refine precision oncology. Fourteen clinical questions regarding circulating tumor deoxyribonucleic acid comprehensive genomic profiling including the timing of testing and considerations for interpreting results were established by searching and curating associated literatures, and corresponding recommendations were prepared based on the literature for each clinical question. Final consensus recommendations were developed by voting to determine the level of each recommendation by the Committee members.

[Learning from My Experience: Outpatient Care for Cancer Multigene Genomic Testing].

We established an outpatient service in November 2017 to provide cancer gene profiling test services to cancer patients. To date, we have seen approximately 100 patients. Our staff includes genetic counselors and nurses specialized in genetic medicine. Our experience highlights the importance of healthcare professionals having in-depth knowledge of cancer therapeutic drugs and/or investigational drugs based on cancer genome medicine. Recently, poly(ADP-ribose) polymerase (PARP) inhibitors have been approved for treating breast cancer patients with germline BRCA mutation; thus, in-depth knowledge of genetics and skills for genetic counseling are often considered indispensable in working with cancer patients. However, because the prompt treatment of clear and present cancer is the top priority in clinical settings, providing genetic information at that time, including that of unaffected family members, is of low priority for most patients who are dealing with the severe side effects of anti-cancer therapies. Pharmacists have an essential role to play in cancer therapeutics, talking with patients in order to assess their condition and to clarify the status of their treatment with anticancer agents. Genetic pharmacists should therefore work closely with genetics nurses and genetic counselors in the clinical practice of cancer genomic medicine. In this symposium, I would like to describe our experience caring for patients through our outpatient service, and to discuss the ideal framework for multidisciplinary cooperation to promote cancer genomic medicine.

Genetic profiling of patients with adenoid cystic carcinoma of the Bartholin's glands reveals potential new routes for targeted therapies: a case report.

BACKGROUND: Bartholin gland carcinomas (BGCs) are rare tumor types, for which no molecular analyses including genomic sequencing have been reported to date. Adenoid cystic carcinomas (ACCs) of the Bartholin's glands are an atypical histological type of BGC, and currently nothing is known regarding their genetic profiles or similarity to ACC carcinogenesis in other organs including the salivary glands, thereby limiting possible therapeutic options using precision medicine. CASE PRESENTATION: We used targeted gene sequencing to analyze the occurrence of 160 cancer-related genes in two patients with BG-ACC. KRAS and KDM6A mutations were detected in tumor samples collected from each patient. No KRAS mutations have been previously reported in salivary gland ACCs, indicating that the carcinogenesis of BG-ACC differs from that of the salivary gland ACCs. KDM6A mutations are often reported in salivary gland ACCs and facilitate novel gene-targeted therapy, including the use of BET and HDAC inhibitors. CONCLUSIONS: A better understanding of the underlying genetic mechanisms will help to clarify the carcinogenesis of BG-ACC. In turn, this will enable treatment with novel targeting agents, as well as the initial exploration of gene-based precision oncological therapies, which aim to improve treatment outcomes for patients with this disease.

Intratumoral Genomic Heterogeneity May Hinder Precision Medicine Strategies in Patients with Serous Ovarian Carcinoma.

Precision medicine, which includes comprehensive genome sequencing, is a potential therapeutic option for treating high-grade serous carcinoma (HGSC). However, HGSC is a heterogeneous tumor at the architectural, cellular, and molecular levels. Intratumoral molecular heterogeneity currently limits the precision of medical strategies based on the gene mutation status. This study was carried out to analyze the presence of 160 cancer-related genetic alterations in three tissue regions with different pathological features in a patient with HGSC. The patient exhibited histological heterogeneous features with different degrees of large atypical cells and desmoplastic reactions. TP53 mutation, ERBB2 and KRAS amplification, and WT1, CDH1, and KDM6A loss were detected as actionable gene alterations. Interestingly, the ERBB2 and KRAS amplification status gradually changed according to the region examined. The difference was consistent with the differences in pathological features. Our results demonstrate the need for sampling of the appropriate tissue region showing progression of pathological features for molecular analysis to solve issues related to tumor heterogeneity prior to developing precision oncology strategies.

Gastric cancer cell line Hs746T harbors a splice site mutation of c-Met causing juxtamembrane domain deletion.

Receptor tyrosine kinases (RTKs) are involved in oncogenesis and disease progression for many cancers. Inhibitors targeting them are vigorously developed and some of them are tested in the clinical setting. Amplifications of certain RTKs (c-Met, FGFR2 and ErbB2) have been associated with human gastric cancer progression. According to our genome-wide scans of genetic lesions in 34 gastric cancer cell lines using high-density single-nucleotide polymorphism genotyping microarrays, we confirmed that the c-met locus was amplified in four gastric cancer cell lines (Hs746T, MKN45, NUGC4 and SNU5). It was reported that somatic mutation is occasionally detected in tumor samples of a certain type of cancer with gene amplification. Previous reports showed gastric cancers harbored mutations of FGFR2 and ErbB2, but c-Met oncogenic mutation had not yet been reported. We performed mutational analysis of the cytoplasmic domains of c-Met using the genome DNA of the gastric cancer cell lines, and found that Hs746T cells had a splice site mutation of exon 14. By cDNA sequencing and Western blotting, we showed that the mutation caused juxtamembrane domain deletion. Previously, this mutation had been detected only in lung cancer specimens and this deletion resulted in the loss of Cbl E3-ligase binding causing decreased ubiquitination and delayed down-regulation. In conclusion, four gastric cancer cell lines harbored amplification of c-met locus, and among them, Hs746T had a putative oncogenic mutation with amplification. This information will be useful for screening of inhibitors targeting gastric cancer with c-Met aberration.

Strategy for differentiating autoimmune pancreatitis from pancreatic cancer.

OBJECTIVES: It is of utmost importance that autoimmune pancreatitis (AIP) be differentiated from pancreatic cancer (PC) because some AIP cases undergo unnecessary laparotomy or pancreatic resection on suspicion of PC. This study aimed to develop an appropriate strategy for differentiating between AIP and PC. METHODS: Clinical, serological, and radiological features of 17 AIP patients forming a masslike lesion on pancreas head and 70 patients with pancreatic head cancer were compared. RESULTS: Numerous findings can be used to distinguish between AIP and PC, and the following are more likely in AIP: fluctuating jaundice; elevated serum IgG4 levels; delayed enhancement of the enlarged pancreas and a capsule-like low-density rim on computed tomography; long or skipped narrowed portion with side branches of the main pancreatic duct without upstream dilatation on endoscopic retrograde pancreatography, extrapancreatic lesions, such as stenosis of the intrahepatic bile duct, salivary gland swelling, and retroperitoneal mass; and responsiveness to steroid therapy. CONCLUSIONS: In elderly male patients presenting with obstructive jaundice and a pancreatic mass, AIP should be considered in the differential diagnosis. Based on a combination of clinical, serological, and radiological findings, AIP can be differentiated from PC. An algorithm for management of patients with a masslike lesion on pancreas head is presented.

Infrequent somatic mutations of the ICAT gene in various human cancers with frequent 1p-LOH and/or abnormal nuclear accumulation of beta-catenin.

Abnormal nuclear accumulation of beta-catenin (CTNNB1) plays one of the key roles in the upregulation of the Wnt signalling pathway that can cause acceleration of cell proliferation. ICAT, inhibitor of beta-catenin and TCF4/beta-catenin-interacting protein, was isolated and mapped to 1p36, a frequent target for LOH in many human cancers. We have previously observed that a number of tumors showing abnormal accumulation of the CTNNB1 protein do not harbor a mutation of the CTNNB1 gene. We studied the precise localization and genomic structure of the ICAT gene and analyzed its mutations in 178 human tumors developed in organs with frequent nuclear accumulation of the CTNNB1 protein and/or frequent LOHs of 1p36, but no genetic alterations were observed. Our results imply that i) genetic alteration of the ICAT gene does not play an important role in abnormal accumulation of CTNNB1 that would cause up-regulation of the Wnt signalling pathway, ii) mechanisms other than genetic alteration may have inactivated ICAT function, or iii) gene(s) on 1p36 other than ICAT may be the responsible tumor suppressor gene for tumors that show frequent 1p36-LOH.