Immune checkpoint inhibitors of programmed cell death 1 (PD-1) and its ligand (PD-L1) have led to a paradigm shift in cancer treatment. Understanding the clinical efficacy and safety profile of these drugs is necessary for treatment strategy in clinical practice.OBJECTIVE To assess the differences between anti-PD-1 and anti-PD-L1 regarding efficacy and safety shown in randomized clinical trials across various tumor types.

Background: There is currently a lack of effective biomarkers to evaluate efficacy of neoadjuvant therapy (NAT) for resectable non-small cell lung cancer (NSCLC) patients. Circulating tumor DNA (ctDNA) has been investigated as a non-invasive tool for the assessment of tumor burden and minimal residual disease (MRD). The utility of ctDNA profiling in reflecting NAT efficacy, however, has not been confirmed. This study explored the association of ctDNA change with treatment response to NAT and recurrence-free survival (RFS) after surgery.Methods: Eligible patients with stage IB-IIIA NSCLC were retrospectively included if they had received neoadjuvant immunotherapy combined with chemotherapy (IO+Chemo), dual immunotherapy (IO+IO), or chemotherapy alone (Chemo). We conducted ctDNA profiling before and after NAT, after surgery, and during follow-ups using an ultra-deep lung cancer-specific MRD (LC-MRD) sequencing panel.Results: A total of 22 patients who received NAT followed by surgery between August 2018 and July 2019 were included in this study. The major pathological response (MPR) rates were 58.33% (7/12) in the IO+Chemo group, 25.00% (1/4) in the IO+IO group, and 16.67% (1/6) in the Chemo group. The ctDNA dynamics during NAT were highly concordant with pathologic response, demonstrating 100% sensitivity and 83.33% specificity, for an overall accuracy of 91.67%. Pre-surgery detectable ctDNA (after NAT) trended to correlate with inferior RFS [hazard ratio (HR), 7.41; 95% confidence interval (CI): 0.91-60.22, log-rank P=0.03]. At 3-8 days after surgery, ctDNA was detectable in 31.8% of patients and was an independent risk factor for recurrence (HR, 5.37; 95% CI: 1.27-22.67; log-rank P=0.01). The presence of ctDNA at 3 months after surgery showed 83% sensitivity and 90% specificity for predicting relapse (C-index, 0.79; 95% CI: 0.62-0.95). During disease monitoring after surgery, molecular recurrence by means of ctDNA preceded radiographic relapse, with a median time of 6.83 months.Conclusions: This study investigated the potential of ctDNA in evaluating NAT efficacy in NSCLC, implying the high concordance between ctDNA and pathological response. We also set out the prognostic value of perioperative ctDNA in predicting recurrence.

Background: Immunotherapy combined with platinum-based chemotherapy is now the standard first-line treatment for non-small cell lung cancer (NSCLC) patients. However, limited evidence exists to show the efficacy of immunotherapy plus taxanes for patients who have progressed after platinum-based chemotherapy. Methods: The immunotherapy naïve patients with metastatic NSCLC who received anti-PD-1/PD-L1 monotherapy or combined with nab-paclitaxel after prior platinum-based chemotherapy from 2015 to 2018 in PLA General Hospital were identified. The progression-free survival, overall survival (OS), objective response rate (ORR), disease control rate (DCR) and safety were assessed. Results: Of 57 patients, 40 were treated with anti-PD-1/PD-L1 monotherapy and 17 were treated with anti-PD-1/PD-L1 plus nab-paclitaxel. With a median OS follow-up of 16.3 months, the nab-paclitaxel group showed significantly longer OS compared with the immune monotherapy group (median, 28.6 months versus 15.9 months, log-rank p = 0.020). When adjusted by covariates in COX proportional regression model, both the treatment group [ p = 0.009, hazard ratio (HR) 0.361; 95% confidence interval (CI) 0.168–0.773] and performance status ( p = 0.003, HR 0.372; 95% CI 0.192–0.721) demonstrated independent association with the longer OS from combination therapy. In addition, ORR was 23.5% (4/17) in the immune checkpoints inhibitors (ICIs) plus nab-paclitaxel group versus 13.5% (5/37) in immune monotherapy group ( p = 0.439), with a DCR of 88.2% (15/17) and 59.5% (22/37) ( p = 0.034), respectively. The incidence of grade 3/4 adverse events was 23.5% (4/17) in the combination group and 2.5% (1/40) in the immune monotherapy group. Conclusion: PD-1/PD-L1 inhibitor plus nab-paclitaxel resulted in significantly longer OS and higher response versus ICI single agent in metastatic NSCLC patients who have progressed after platinum-based chemotherapy. These findings need to be further explored by prospective studies.

Background Isocitrate dehydrogenase (IDH) is an enzyme family involved in cell aerobic metabolism of tricarboxylic acid cycle. However, the landscape of IDH mutations in pan‐cancer has not been fully characterized. Methods Tissue or blood samples were subjected to next‐generation sequencing (NGS) for detection the IDH mutation. Results A total of 28.868 patients from more than 20 solid tumor species were analyzed. A total of 374 cases (1.30%) with IDH mutations were identified. Among all the IDH mutations cases, 80 (21.4%) were biliary tract cancer (BTC), 80 (21.4%) were lung cancer, 57 (15.2%) were liver cancer, and 42 (11.2%) were colorectal cancer. The most common IDH variant were IDH1 and IDH2 which were discovered in 0.81% cases and 0.47% cases, respectively. However, there were significant differences in IDH1 and IDH2 mutation frequency among different tumor species (p = 0.0003). Of the patients with IDH1 mutations, about 53.0% of these mutations occur in codons 132. Codons 172 (25.4%) was high‐frequency mutation subtypes in IDH2 mutation. TP53, PBRM1, and BAP1 were the most significantly mutated genes in BTC which were different from others cancer. Moreover, TMB were significantly higher in lung cancer, colorectal cancer, and gastric cancer than BTC (p = 0.0164, p < 0.0001, p = 0.0067, respectively) and BTC patients with IDH mutation had lower TMB compared with wild‐type IDH. Conclusion Somatic IDH mutation was found in multiple solid tumors and IDH would be a driver gene in BTC.

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ObjectiveEmerging evidence showed that immune checkpoint inhibitors (ICIs) lead to hyperprogressive disease (HPD) in a small proportion of patients. There is no well-recognized standard for the evaluation of HPD. Comprehensive exploration of HPD definition system in gastrointestinal cancer treated with ICI is lacking to date.MethodsA total of 126 patients with advanced or metastatic gastrointestinal cancer treated with ICI monotherapy were analyzed. Seven definitions of HPD were defined with tumor growth kinetics (TGK) or tumor growth rate (TGR) by including new lesions or not, and with different cutoffs. Incidence and performance of different criteria were compared. Clinicopathologic characteristics and baseline genomic variations associated with HPD were also explored.ResultsTumor growth kinetics ratio of more than two fold that incorporated new lesions into calculation of HPD outperformed other definitions by successfully stratifying 14 patients (11.1%) with both accelerated disease progression (median PFS, 1.62 versus 1.93 months; hazard ratio, 1.85; 95% CI, 0.98 to 3.48; P = 0.059) and worse overall survival (median OS, 3.97 versus 10.23 months; hazard ratio, 2.30; 95% CI, 1.11 to 4.78; P = 0.021). Baseline genomic alterations in circulating tumor DNA, including SMARCA2, MSH6, APC signaling pathway, and Wnt signaling pathway, might be associated with the risk of HPD.ConclusionIncorporating new lesions emerging during the treatment was shown to be reliable for the assessment of TGK. TGK serves as a more convenient way to reflect tumor growth acceleration compared with TGR. Genomic alterations were suggested to be associated with the occurrence of HPD.

Background: Gastric cancer (GC) is one of the leading causes of cancer death in China, while the nature of genetic factors related to GC has not been well-studied. Objectives: To assess the inherited genetic factors regarding pathogenic germline mutations in Chinese GC population. Methods: Genomic profiling of DNA was performed through next-generation sequencing with 381 cancer-related genes on tissue from patients with GC between January 1, 2017, and May 7, 2019. Results: 470 GC patients were included for analysis. A total of 28 (6.0%) patients were identified to harbor 25 different pathogenic or very likely pathogenic germline mutations in 15 genes. The variants fell most frequently in BRCA2 (n = 6, 1.28%), CHEK2 (n = 5, 1.06%), MUTYH (n = 3, 0.64%), CDH1 (n = 2, 0.43%), and ATM (n = 2, 0.43%). Of all the germline-mutated genes, 66.7% (n = 10) lay in the DNA damage repair pathways. Seven patients were identified to have a high TMB status, among whom two were also identified as MSI-H. Overall, 20 out of the 28 patients (71.4%) carried clinically actionable mutations. Conclusions: Our study has depicted the spectrum of pathogenic germline mutations in Chinese GC patients, which may provide valuable clues for the assessment of the genetic susceptibility and clinical management in GC.

e13638 Background: Isocitrate dehydrogenase (IDH) is an enzyme family involved in cell aerobic metabolism of tricarboxylic acid cycle, including IDH1-3. Mutations in IDH family are common in glioma and hematologic malignancies. IDH inhibitors have shown promising efficacy not only in hematologic malignancies but also cholangiocarcinoma patients harboring IDH1 mutations. However, the landscape of IDH mutations in pan-cancer has not been fully characterized. Methods: Tissue or blood samples were subjected to NGS in a College of American Pathologists-certified and Clinical Laboratory Improvement Amendments-accredited lab for detection the IDH mutation. Results: A total of 12,372 patients from more than 20 solid tumor species were analyzed, including biliary carcinoma (960 cases), liver cancer (1433 cases), lung cancer (3557 cases) and colorectal cancer (1310 cases). 105 cases (0.8%) with IDH mutations were identified. The average age for patients harboring IDH mutations was 59 years (range, 29-80 years). Among all the IDH mutations cases, 49 (47%) were biliary tract cancer, 25 (24%) were liver cancer, 16 (15%) were lung cancer and 7 (7%) were colorectal cancer. The most common IDH variant were IDH1 and IDH2 which were discovered in 84 cases and 21 cases, respectively. IDH1 R132C mutation represents 45.7% (n = 48) of all IDH mutations. Other mutations found affecting either IDH1 at Arg132 included R132L (n = 24), R132G (n = 5), R132H (n = 5) and R132S (n = 2) or IDH2 at Arg172 (R172K most frequently). In addition, IDH1/2 gene was most frequently co-mutated with TP53 and ARID1A. Conclusions: Somatic IDH1/2 mutations are found in multiple solid tumors and patients with IDH1/2 mutations may benefit from IDH1/2 inhibitors in the future.