[Preclinical study of T cell receptor specifically reactive with KRAS G12V mutation in the treatment of malignant tumors].

OBJECTIVE: KRAS gene is one of the most common mutations of proto-oncogenes in human tumors, G12V is one of the most common mutation types for KRAS. It's challenging to chemically acquire the targeted drug for this mutation. Recent studies reported that this mutation peptides can form a neoepitope for T cell recognition. Our study aims to clone the T cell receptor (TCR) which specifically recognizes the neoepitope for KRAS G12V mutation and constructs TCR engineered T cells (TCR-T), and to investigate if TCR-Ts have strong antitumor response ability. METHODS: In this study, tumor infiltrating lymphocytes were obtained from one colorectal cancer patient carrying KRAS G12V mutation. Tumor-reactive TCR was obtained by single-cell RT-5' rapid-amplification of cDNA ends PCR analysis and introduced into peripheral blood lymphocytes to generate TCR-Ts. RESULTS: We obtained a high-affinity TCR sequence that specifically recognized the HLA-A*11:01-restricted KRAS G12V8-16 epitope: KVA11-01. KVA11-01 TCR-T could significantly kill various tumor cells such as PANC-1, SW480 and HeLa (overexpressing HLA-A*11:01 and KRAS G12V), and secreting high levels of interferon-γ (IFN-γ). Non-specific killing experiments suggested KVA11-01 specifically recognized tumor cells expressing both mutant KRAS G12V and HLA-A*11:01. In vivo assay, tumor inhibition experiments demonstrated that infusion of approximately 1E7 KVA11-01 TCR-T could significantly inhibit the growth of subcuta-neously transplanted tumors of PANC-1 and HeLa (overexpressing HLA-A*11:01 and KRAS G12V) cells in nude mice. No destruction of the morphologies of the liver, spleen and brain were observed. We also found that KVA11-01 TCR-T could significantly infiltrate into tumor tissue and had a better homing ability. CONCLUSION: KVA11-01 TCR-T cells can effectively target a variety of malignant tumor cells carrying KRAS G12V mutation through in vitro and in vivo assay. KVA11-01 TCR-T cells have excellent biological activity, high specificity of target antigen and homing ability into solid tumor tissue. KVA11-01 TCR-T is expected to be an effective treatment for patients with KRAS G12V mutant solid malignancies.

Hypomethylating agents for elderly patients with acute myeloid leukemia: a PRISMA systematic review and meta-analysis.

OBJECTIVE: Abnormal DNA methylation plays a critical role in acute myeloid leukemia (AML) pathogenesis and hypomethylating agents (HMAs) such as decitabine (5-aza-29-deoxycytidine) and azacitidine (5-azacytidine) are considered efficacious for treating AML. This study aimed to identify if HMAs have therapeutic advantages compared with conventional care regimens (CCR) or placebo in elderly AML patients. MATERIALS AND METHODS: We systematically searched PubMed, Embase, and Cochrane Central Register of Controlled Trials from inception to November July 15, 2020. Randomized controlled trials that compared the efficacy and adverse events associated with HMAs, CCR, or placebo were searched. RevMan 5.3 software was used to calculate the hazard ratio (HR) and risk ratio (RR) with a 95% confidence interval (CI). RESULTS: Seven trials with a total of 1966 participants were included. Meta-analyses showed that the overall survival of HMAs was better than that of CCR [HR=0.76, 95% CI (0.69-0.85), (p<0.01)], and the complete remission rate of elderly AML patients was increased by HMAs compared with CCR [RR=1.46, 95%CI (1.08-1.99), p=0.01)]. HMA treatment showed higher incidence of neutropenia [RR=1.30 (95%CI 1.07-1.59, p=0.008)], thrombocytopenia [RR=1.14 (95%CI 1.01-1.59, p=0.04)], and pneumonia [RR=1.37 (95%CI 1.06-1.76, p=0.02)] compared with CCR. CONCLUSIONS: Although HMAs cause a higher incidence of adverse events such as neutropenia, thrombocytopenia, and pneumonia, demethylation drugs are well-tolerated and effective for treating AML in the elderly.