Previous studies found patients with POLE exonuclease domain mutations (EDMs) in targeted exons were related to significant better outcomes in stage II-III colorectal cancer (CRC). The detailed mutational profile of the entire POLE exonuclease domain, tumor mutation burden (TMB) and immune cell infiltration in POLE EDMs tumors, and the prognostic value of such mutations in stage II CRCs were largely unknown to us. This study was to clarify the characteristics, immune response and prognostic value of somatic POLE EDMs in stage II CRC. A total of 295 patients with stage II CRC were sequenced by next-generation sequencing with a targeted genetic panel. Simultaneous detection of the immune cells was conducted using a five-color immunohistochemical multiplex technique. The detailed molecular characteristics, tumor-infiltrating lymphocyte (TIL) and prognostic effect of POLE EDMs in stage II CRC were analyzed. For stage II CRCs, the POLE EDMs were detected in 3.1% of patients. Patients with POLE EDMs were more prone to be microsatellite instability-high (MSI-H) (33.3% vs 11.2%, p=0.043), younger at diagnosis (median 46 years vs 62 years, p<0.001) and more common at right-sided location (66.7% vs 23.1%; p=0.003). All patients with POLE EMDs were assessed as extremely high TMB, with a mean TMB of 200.8. Compared with other stage II CRCs, POLE EDMs displayed an enhanced intratumoral cytotoxic T cell response, evidenced by increased numbers of CD8+TILs and CD8A expression. Patients with stage II CRCs could be classified into three risk subsets, with significant different 5 years disease-free survival rates of 100% for POLE EDMs, 82.0% for MSI-H and 63.0% for MSS, p=0.013. In conclusion, characterized by a robust intratumoral T cell response, ultramutated POLE EDMs could be detected in a small subset of stage II CRCs with extremely high TMB. Patients with POLE EDMs had excellent outcomes in stage II CRCs, regardless of MSI status. Sequencing of all the exonuclease domain of POLE gene is recommended in clinical practice.

Exposure to spaceflight and microgravity causes physiologic and psychologic changes including bone loss, cardiovascular dysfunction, and immune dysfunction. Anemia and hematopoietic disorders are observed in astronauts after spaceflight. Hematopoietic stem and progenitor cells (HSPCs), which can self‐renew and give rise to all blood cells, play vital roles in hematopoiesis and homeostasis; however, the molecular mechanisms responsible for the impacts of microgravity on the proliferation of HSPCs remain unclear. We maintained mouse bone marrow HSPCs in the presence of stem cell factor for 12 d under spaceflight and simulated microgravity conditions, respectively, and analyzed cell proliferation and gene expression. Both spaceflight and simulated microgravity significantly decreased the number of HSPCs, mainly by blocking cell cycle at G1/S transition, but did not affect their differentiation abilities. RNA‐sequencing data indicated that genes related to cell proliferation were down‐regulated, whereas the genes related to cell death were up‐regulated under microgravity. Among the gene signatures, we identified that the Kit‐Ras/cAMP–cAMP response element‐binding protein pathway might be one of the major microgravity‐regulated pathways during HSPC proliferation. Furthermore, the quantification of notable genes was validated at the mRNA levels under simulated microgravity condition. Overall, these results would help us to understand the intracellular molecular mechanisms regulating microgravity‐inhibited proliferation of HSPCs.—Wang, P., Tian, H., Zhang, J., Qian, J., Li, L., Shi, L., Zhao, Y. Spaceflight/microgravity inhibits the proliferation of hematopoietic stem cells by decreasing Kit‐Ras/cAMP‐CREB pathway networks as evidenced by RNA‐Seq assays. FASEB J. 33, 5903–5913 (2019). http://www.fasebj.org

Background: The aim of this study was to evaluate the clinical value of plasma cell-free DNA (cfDNA) mutation profiles in patients with oesophageal squamous cell carcinoma (OSCC) who received neoadjuvant chemotherapy. Methods: Twenty-two OSCC patients received neoadjuvant chemotherapy and were divided into two groups according to their response to the therapy. Fifteen patients were in the responsive group, and seven patients were in the non-responsive group. The blood samples were collected, and the plasma cfDNA mutation profiles were sequenced by a cancer gene-targeted next-generation sequencing (NGS) panel. Results:The driver gene molecular mutation burden (MMB) was significantly higher in the non-responsive group compared with the responsive group. Furthermore, we found that the differential MMB included the DNA damage response, Wnt, PI3K, Hippo, RTK/RAS, p53, and AHR pathway. The MMB yielded an area under the receiver operation characteristic (ROC) curve of 0.89 for predicting the response to neoadjuvant chemotherapy. The cfDNA copy number variations (CNVs) yielded an area under ROC curve of 1.0 for predicting the response to neoadjuvant chemotherapy. Conclusions: The driver gene MMB and CNVs in plasma cfDNA may be potential biomarkers for predicting the response to neoadjuvant chemotherapy in patients with OSCC.

This study aimed to validate the prognostic value of Immunoscore (IS) in stage II colorectal cancer (CRC), and explore the roles of IS and circulating tumor DNA (ctDNA) in the adjuvant treatment for early-stage CRC. Resected tumor samples from stage II CRC patients were collected from the Sun Yat-sen University Cancer Center. The densities of CD3+ and CD8+ lymphocytes were quantified and converted to IS and classified into Low, Intermediate (Int), and High groups according to predefined cutoffs. A total of 113 patients were included in the study. Patients with IS-High, Int, and Low were 43 (38%), 62 (55%), and 8 (7%), respectively. Patients with IS-High had an excellent clinical outcome, with none recurring during a median follow-up of 3 years, including 15 (35%) clinical high-risk patients. The 3-year disease-free survival (DFS) was 100% for IS-High, 76% for IS-Int, and 47% for IS-Low ( P < .001). In the multivariate Cox analysis, IS was the only significant parameter associated with DFS. IS-Int and IS-Low patients with adjuvant chemotherapy had improved DFS compared to those who did not receive adjuvant chemotherapy (HR = 0.3; 95% CI 0.1–0.92; P = .026). Among the 49 patients with postoperative ctDNA data, IS-High patients had the lowest ctDNA positivity rate, suggesting that they were most eligible for chemotherapy-free treatment. IS had a strong prognostic value in Chinese patients with stage II CRC and demonstrates its clinical utility. IS and ctDNA will jointly optimize the adjuvant treatment strategies for early-stage CRC.

Patients with ROS1-rearranged non-small cell lung cancer (NSCLC) inevitably relapse after first-line targeted therapy with tyrosine kinase inhibitors. Efficacy of checkpoint inhibitor-based therapy on ROS1-positive NSCLC in second-line setting and change of immune factors during treatment are rarely studied. We report a ROS1-rearranged stage ⅢB lung adenocarcinoma patient who was resistant to ceritinib after developing a secondary ROS1 F2004L mutation. He received eight cycles of nivolumab plus chemotherapy and had an initial partial response, but brain metastases appeared in the seventh cycle. Lorlatinib was confirmed to have activity against CD74–ROS1 with F2004L in vitro, and was administered to this patient as the third-line therapy. The patient responded well to lorlatinib and had no relapse. We explored the tumor immune microenvironment (TIME) during immune-chemotherapy by multiplex immunohistochemistry, RNA sequencing, and multiplex plasma protein immunoassay. The results show that the TIME was active and plasma inflammatory factors were increased when the patient responded to immune-chemotherapy, while the plasma inhibitory checkpoint proteins, lymphocyte-activation gene 3, B and T lymphocyte attenuator, programmed cell death ligand 1 (PD-L1), and PD-1, were increased when the disease progressed. Moreover, the PD-L1 expression on tumor tissue was upregulated during treatment, predicting the limited benefit from immune-chemotherapy. This case report suggests that lorlatinib is a better choice than immune-chemotherapy in second-line setting for patients with similar genomic characteristics, and that monitoring the immune components during immunotherapy may help to predict disease response.