Published papers

Circulating tumor DNA (ctDNA) is the fraction of cell-free DNA in patient blood that originates from a tumor. Advances in DNA sequencing technologies and our understanding of the molecular biology of tumors have increased interest in exploiting ctDNA to facilitate detection of molecular residual disease (MRD). Analysis of ctDNA as a promising MRD biomarker of solid malignancies has a central role in precision medicine initiatives exemplified by our CIRCULATE-Japan project involving patients with resectable colorectal cancer. Notably, the project underscores the prognostic significance of the ctDNA status at 4 weeks post-surgery and its correlation to adjuvant therapy efficacy at interim analysis. This substantiates the hypothesis that MRD is a critical prognostic indicator of relapse in patients with colorectal cancer. Despite remarkable advancements, challenges endure, primarily attributable to the exceedingly low ctDNA concentration in peripheral blood, particularly in scenarios involving low tumor shedding and the intrinsic error rates of current sequencing technologies. These complications necessitate more sensitive and sophisticated assays to verify the clinical utility of MRD across all solid tumors. Whole genome sequencing (WGS)-based tumor-informed MRD assays have recently demonstrated the ability to detect ctDNA in the parts-per-million range. This review delineates the current landscape of MRD assays, highlighting WGS-based approaches as the forefront technique in ctDNA analysis. Additionally, it introduces our upcoming endeavor, WGS-based pan-cancer MRD detection via ctDNA, in our forthcoming project, SCRUM-Japan MONSTAR-SCREEN-3.

Renal cell carcinoma unclassified with medullary phenotype (RCCU-MP) is an extremely rare variant of kidney cancer with poor prognosis. Recently, immune checkpoint inhibitors (ICIs) have been the mainstay of treatment for advanced clear cell renal cell carcinoma (RCC). However, the efficacy of ICI in the treatment of RCCU-MP remains unclear. Here, we report about a 63-year-old Japanese man who was referred to our hospital with a diagnosis of RCC of the left kidney with multiple-lymph node involvement (cT3aN1M1). The patient underwent nephrectomy with lymph node biopsy, which was histopathologically diagnosed as RCCU-MP. Thereafter, he received combined immune checkpoint blockade with nivolumab and ipilimumab. After induction therapy, follow-up computed tomography revealed shrinkage of the metastatic lymph nodes. Moreover, the patient was relieved of his subjective symptoms and his performance status improved. However, after 15 months, maintenance ICI therapy was discontinued because of disease progression, and the patient died 28 months after diagnosis. Longitudinal analysis of peripheral blood mononuclear cells revealed increased stem cell memory and central memory CD8+ T-cell subsets during response to therapy and enhanced expression of exhaustion markers on CD8+ T cells upon treatment resistance. Combined immune checkpoint blockade could be effective in the treatment of metastatic RCCU-MP.

We report the case of a 75-year-old woman with a pancreatic body mass. Pathological findings from endoscopic ultrasonography-guided fine-needle aspiration revealed medullary carcinoma of the pancreas (MCP). Deficient mismatch repair (dMMR) and high microsatellite instability (MSI-H) were identified through immunohistochemistry and next generation sequencing, respectively. While immunohistochemistry suggested MLH1 abnormality, no MLH1 mutation was; hypermethylation of the MLH1 promoter was later confirmed via bisulfite sequencing. The patient initially received nab-paclitaxel plus gemcitabine, achieving tumor shrinkage. Upon tumor regrowth, she was treated with the anti-programmed cell death-1 immune checkpoint inhibitor (ICI) pembrolizumab, which resulted in significant tumor reduction. This is the first case report of MCP with dMMR/MSI-H due to MLH1 promoter hypermethylation, effectively treated with an ICI.

Cetuximab every 2 weeks (Q2W) dosing schedule is approved by the US FDA and by the Japanese Pharmaceuticals and Medical Devices Agency in patients with metastatic colorectal cancer and squamous cell carcinoma of the head and neck. Phase II trials have found comparable efficacy and safety for the weekly (Q1W) and Q2W schedules, and real-world studies have shown noninferiority of the Q2W compared with the Q1W schedule. Several guidelines recommend cetuximab Q2W administration as an alternative to the Q1W dosing schedule. Cetuximab Q2W can be administered with a Q2W dose of chemotherapy, making it a more convenient option to the Q1W schedule, potentially resulting in reduced costs for administration, increased flexibility for clinical staff and improved patient adherence.

BACKGROUND: Although several randomized trials (RCTs) showed survival benefits of immune checkpoint inhibitor (ICI) plus first-line chemotherapy for advanced gastric or gastroesophageal cancer (AGC), these trials could enroll patients who fulfilled the strict eligibility criteria or waited for certain screening period for central assessment of PD-L1 status. METHODS: We retrospectively compared characteristics and clinical outcomes of the patients with AGC who received first-line chemotherapy in control arm of RCTs with ICIs (control group) or clinical practice (practice group) at our institution from February 2016 to April 2019. RESULTS: The control group had a better baseline Eastern Cooperative Oncology Group performance status (PS0, 81.2% vs. 51.4%, p < 0.001) and a longer interval from first visit to first-line chemotherapy initiation (19 days vs. 9 days, p < 0.001) than the practice group. Median overall survival (OS) was 20.3 months in control group and 15.7 months in practice group, with a trend of longer OS in control group than that in practice group (hazard ratio, 0.71; p = 0.062). More patients in control group were treated with subsequent chemotherapy including ICIs. CONCLUSION: Patients with AGC in RCTs of ICIs had a better PS or a higher chance to receive subsequent chemotherapy, resulting in a better prognosis than those treated in clinical practice. This information should be considered when interpreting RCT results and applying new treatments into clinical practice.

PURPOSESeveral lines of treatment can be used sequentially in patients with metastatic colorectal cancer. We investigated the evolution of patient/tumor characteristics and their prognostic impact across treatment lines to develop an overall prognostic score (OPS).PATIENTS AND METHODSIndividual patient data from 48 randomized trials were analyzed. The end point was overall survival (from random assignment to death). Missing data were imputed. The complete data set was then separated into construction (80%) and validation sets (20%). The Cox's model was used to define risk groups for survival using the OPS. The discrimination capability was assessed in each treatment-line via bootstrapping to obtain optimism-corrected calibration and discrimination C-indices. Internal validation was done in the validation set.RESULTSA total of 37,560 patients (26,974 in first-line [1L], 7,693 in second-line [2L], and 2,893 in third-line [3L]) were analyzed. Some clinical, biological, and molecular characteristics of patients/tumors included in therapeutic trials evolve over the lines. Seven independent prognostic variables were retained in the final multivariate model common to all lines: Eastern Cooperative Oncology Group performance status, hemoglobin, platelet count, WBC/absolute neutrophil count ratio, lactate dehydrogenase, alkaline phosphatase, and the number of metastatic sites. The OPS was used to define four patient subgroups with significantly different prognoses in 1L, 2L, and 3L, separately, with adequate C-indices: 0.65, 0.66, and 0.69 in the construction set and 0.65, 0.66, and 0.68 in the validation set, respectively. The OPS was not predictive, with 3L drugs (v placebo) or subsequent line (2L/1L or 3L/2L) extending survival in all prognostic groups.CONCLUSIONThe same prognostic model using practical variables can be used before all treatment lines. The OPS could better stratify patients in future clinical trials and help to therapeutic decision in routine practice.

Background: Zolbetuximab, a monoclonal antibody targeting claudin 18.2 (CLDN18.2), plus chemotherapy has become a standard treatment for CLDN18.2-positive advanced gastric cancer and is frequently associated with early-onset gastrointestinal (GI) toxicities. While zolbetuximab-induced gastritis has been observed in preclinical studies, it has not been previously reported in patients. Patients and methods: We retrospectively analyzed patients with human epidermal growth factor receptor 2 (HER2)-negative, CLDN18.2-positive, advanced gastric or gastroesophageal junction cancer who underwent endoscopy during first-line zolbetuximab-containing chemotherapy. Patients who had undergone prior total gastrectomy were excluded. We evaluated associations between gastritis and clinical outcomes including GI toxicities and serum albumin level. Results: Among 58 eligible patients, gastritis was observed in 52 (89.7%) at a median of 7.8 weeks after treatment initiation. Characteristic endoscopic findings included mucosal erythema (100%), white exudate (63.4%), edema (28.8%), and erosions or ulcerations (26.9%). The distribution of gastritis was predominantly diffuse (76.9%) rather than scattered (23.1%), commonly involving multiple gastric regions (90.4%). Patients with diffuse gastritis experienced significantly higher rates of any-grade anorexia compared with those without gastritis (97.5% versus 50.0%, P = 0.005) and more profound serum albumin decline [median decrease –1.2 g/dl, interquartile range (IQR) –1.525 to –0.9 g/dl versus –0.7 g/dl, IQR –0.8 to –0.6 g/dl; P = 0.012]. No patients discontinued treatment due to gastritis. Among 32 patients who underwent follow-up endoscopy during ongoing treatment, improvement was confirmed in 25 patients, and no cases exhibited unresolved gastritis beyond 18 weeks. Conclusions: Early-onset transient gastritis frequently occurred following zolbetuximab-containing therapy and was significantly associated with anorexia and hypoalbuminemia. A deeper understanding of gastritis underlying unique GI toxicities may provide insight into effective management.

We propose CASPER (ChAt, Shift and PERform), a novel dialog system consisting of three types of dialog models: chatter, shifter, and performer. Shifter, which is designed for topic switching, enables a seamless flow of dialog from open-domain chat- to task-oriented dialog. In a user study, CASPER gave a better impression in terms of naturalness of response, lack of forced topic switching, and satisfaction compared with a baseline dialog system trained in an end-to-end manner. In an ablation study, we found that naturalness of response, dialog satisfaction, and task-elicitation rate improved compared with when shifter was removed from CASPER, indicating that topic shift with shifter supports the introduction of natural task-oriented dialog.

Colorectal cancer(CRC)is one of the most commonly diagnosed cancers worldwide. Unresectable advanced, metastatic or recurrent CRC(mCRC)remains incurable for most patients. Systemic chemotherapy is standard treatment for patients with mCRC. The goals of systemic chemotherapy include prolonging survival by stopping cancer progression and palliation. In recent years, advances in the treatment of mCRC have enabled personalized care based on the tumor's molecular profile with improved outcomes for some subtypes. Targeted biologic therapies and immune checkpoint inhibitors have changed the approach to management of uncommon molecularly defined subsets of mCRC. The development of chemotherapy using cytotoxic drugs, biologic monoclonal antibodies, and immune checkpoint inhibitors has prolonged median overall survival up to approximately 30 months. In this report, we describe the evolution of systemic chemotherapy for mCRC, recent advances in standard treatment, and future prospects for the treatment of mCRC.