Purpose: We investigated the value of circulating tumor DNA (ctDNA) in predicting tumor response to neoadjuvant chemoradiotherapy (nCRT), monitoring tumor burden, and prognosing survival in patients with locally advanced rectal cancer (LARC). Experimental Design: This prospective multicenter trial recruited 106 LARC patients for treatment of nCRT followed by surgery. Serial ctDNA were analyzed by NGS at four time points: at baseline, during nCRT, pre-surgery and post-surgery. Results: In total, 1098 mutations were identified in tumor tissues of the 104 patients being analyzed (median, 7 mutations per patient). ctDNA was detected in 75%, 15.6%, 10.5%, and 6.7% of cases at the four time points, respectively. None of the 29 patients with pathological complete response (ypCR) had preoperative ctDNA detected. Preoperative ctDNA positive rate was significantly lower in the well responded patients with pathological tumor regression grade of ypCAP 0-1 than ypCAP 2-3 group (P < 0.001), lower in ypCR than non-ypCR group (P = 0.02), and lower in ypT 0-2 than ypT 3-4 group (P = 0.002). With a median follow-up of 18.8 months, thirteen patients (12.5%) experienced distant metastasis. ctDNA positivity at all four time points was associated with a shorter metastasis-free survival (MFS) (P < 0.05). Multivariate analyses showed that the median VAF of mutations in baseline ctDNA was a strong independent predictor of MFS (HR=1.27, P < 0.001). Conclusions: We show that ctDNA is a real-time monitoring indicator that can accurately reflect the tumor burden. The median VAF of baseline ctDNA is a strong independent predictor of MFS.

Colorectal signet ring cell carcinoma (SRCC) is a rare subtype of colorectal cancer (CRC) with unique characteristics. Due to the limited researches on it, a comprehensive and in-depth understanding of this subtype is still lacking. In this article, we summarize the clinicopathological features and molecular characteristics of colorectal SRCC based on a literature review. Clinically, SRCC has been associated with young age, proximal site preference, advanced tumor stage, high histological grade, high rate of lymph node involvement, frequent peritoneal metastasis, and a significantly poor prognosis. Regarding molecular characteristics, in SRCC, the mutation burden of the classic signaling pathways that include WNT/β-catenin, RAS/RAF/MAPK, and PI3K/AKT/mTOR signaling pathways are generally reduced. In contrast, some genes related to the “epithelial-mesenchymal transition (EMT) process” and the “stem cell properties”, including RNF43, CDH1, and SMAD4, as well as the related TGF-β signaling pathway have been observed more frequently altered in SRCC than in conventional adenocarcinoma (AC). In many studies but not in others, SRCC showed a higher frequency of BRAF mutation, microsatellite instability-high (MSI-H) and CpG island methylator phenotype (CIMP) positive status compared to AC. It has been proposed that colorectal SRCC consists of two subtypes, in which the MSI⁺/CIMP⁺/BRAF⁺/CD3⁺/PD-L1⁺ hypermethylated genotype is more common in the proximal colon, and may represent the potential candidate for immunotherapy. Understanding the special molecular mechanisms related to the aggressive biology of SRCC is of great importance, which may provide a theoretical basis for the development of more targeted and effective treatments for this refractory disease.

Liquid biopsy has been proposed to be a promising noninvasive tool to obtain information on tumor progression. Through a clinical observation of a case series of 6 consecutive patients, we aim to determine the value of circulating tumor DNA (ctDNA) for monitoring the tumor burden during the treatment of colorectal cancer (CRC). We used capture sequencing of 545 genes to identify somatic alternations in primary tumor tissues of the six CRC patients who underwent radical surgery and in 23 plasma samples collected at serial time points. We compared the mutation patterns and variant allele frequencies (VAFs) between the matched tissue and the plasma samples and evaluated the potential advantage of using ctDNA as a better tumor load indicator to detect disease relapse over carcinoembryonic antigen (CEA), cancer antigen (CA) 19–9 and imaging studies. We identified low-frequency mutations with a mean VAF of 0.88% (corresponding to a mean tumor burden of 0.20ng/mL) in the preoperative plasmas of four patients with locally advanced CRC and a subset of mutations shared by their primary tumors. The tumor loads appeared a sudden decrease upon surgery or other adjuvant treatments and then generally maintained at low levels (0.092ng/mL) until disease recurred. ctDNA increased by 13-fold when disease relapsed in one patient while the CEA and CA 19–9 levels remained normal. In this patient, all six somatic mutations identified in the preoperative plasma were detected in the recrudescent plasma again, with five mutations showing allele fraction increase. We described a multi-time-point profile of ctDNA of CRC patients during the course of comprehensive treatment and observed a correlation of ctDNA level with the clinically evaluated tumor progression. This demonstrated a new strategy by analyzing the heterogeneous ctDNA to evaluate and monitor the tumor burden in the treatment and follow-up of CRC patients, with potentially better potency than conventional biomarkers.

INTRODUCTION: Blue rubber bleb nevus syndrome (BRBNS) is a rare systemic venous malformation (VM) disease. The characteristic gastrointestinal (GI) bleeding from multiple VM lesions causes severe chronic anemia which renders most patients depend on lifelong blood transfusion and frequent endoscopic treatment with dismayed outcomes. Although recent case reports suggest that oral sirolimus (rapamycin) is effective, a comprehensive evaluation of its efficacy and safety is in need. METHODS: A prospective study was conducted for both pediatric and adult BRBNS patients with administration of sirolimus at the dose of 1.0 mg/m² to maintain a trough concentration of 3–10 ng/mL. Laboratory tests including complete blood count, biochemical profile, D-dimer, and whole-body magnetic resonance imaging were performed at baseline and 3, 6, and 12 months after treatment. Clinical indicators such as hemoglobin level, lesion size, and transfusion need were evaluated. Adverse effects were recorded regularly. RESULTS: A total of 11 patients (4 males and 7 females) with median age of 14 (range, 5–49) years were recruited. The average lesion size was reduced by 7.4% (P < 0.001), 9.3% (P < 0.001), and 13.0% (P < 0.05) at 3, 6, and 12 months of sirolimus treatment, respectively. Hemoglobin increased significantly after 6- and 12-month treatment (P = 0.006 and 0.019, respectively). Only 1 patient received blood transfusion once during the study. Patients' quality of life and coagulation function were improved. Grade 1–2 adverse effects including oral ulcers (81.8%), acne (27.3%), transient elevation of liver enzymes (18.2%), and hair loss (9.1%) were observed. DISCUSSION: Sirolimus reduces the size of VMs, alleviates GI bleeding, and eliminates transfusion dependence of patients with BRBNS. The drug-related adverse effects are mild and mostly self-limited. These findings support sirolimus as a first-line treatment for GI and cutaneous VMs of BRBNS (see Visual abstract, Supplementary Digital Content, http://links.lww.com/AJG/B819).

Neoadjuvant chemoradiotherapy (nCRT) is the standard for locally advanced rectal cancer (LARC). However, distant metastasis remains the primary cause of treatment failure. Early identification of high-risk individuals for personalized treatment may offer a solution. Circulating tumour DNA (ctDNA) could assist in this process. From September 2017 to June 2019, the study prospectively recruited 113 patients with LARC (cT3-4N0M0 or cTanyN + M0) who underwent nCRT followed by radical surgery across 8 tertiary centers. ctDNA was analysed using large-panel targeted sequencing at baseline, during nCRT, pre-surgery, post-surgery, post-adjuvant chemotherapy (ACT), and during annual follow-ups for 3 years. We analysed 103 tissue and 669 plasma samples from 103 patients. With a median 53-month follow-up, significantly worse progression-free survival (PFS) and overall survival (OS) were observed if median variant allele frequency (mVAF) of baseline ctDNA per patient was ≥0.5% (PFS, HR 4.39, p < 0.001; OS, HR 5.61, p = 0.004) or ctDNA was still detectable two weeks into nCRT (PFS, HR 7.63, p < 0.001; OS, HR 5.08, p < 0.001). Furthermore, when compared to the low-risk (C1) group (characterized by "ctDNA undetected during nCRT with baseline mVAF <0.5%" or "ctDNA undetected during nCRT with TMB (tumour mutational burden) ≥20/Mb"), the high-risk (C2) group (characterized by "ctDNA detected during nCRT" or "baseline mVAF ≥0.5% with TMB <20/Mb") showed significantly worse long-term outcomes (3 y-PFS, 55.9% vs. 94.2%; 3 y-OS, 79.4% vs. 100%). The ctDNA clearance during nCRT, baseline mVAF, and TMB may be effective prognostic indicators. Our findings reaffirm the clinical monitoring value of ctDNA and demonstrate the strong prognostic value of baseline ctDNA and its early clearance status in patients with LARC undergoing nCRT. This highlights the potential of dynamic ctDNA monitoring as actionable stratified indicators to guide personalized neoadjuvant treatment strategies. This work was supported by the Major Grants Program of Beijing Science and Technology Commission (No. D171100002617003) and the National High Level Hospital Clinical Research Funding (2022-PUMCH-C-005).