Potential unreliability of ALK variant allele frequency in the efficacy prediction of targeted therapy in NSCLC / 医学前沿

Anaplastic lymphoma kinase (ALK) is the most common fusion gene involved in non-small cell lung cancer (NSCLC), and remarkable response has been achieved with the use of ALK tyrosine kinase inhibitors (ALK-TKIs). However, the clinical efficacy is highly variable. Pre-existing intratumoral heterogeneity (ITH) has been proven to contribute to the poor treatment response and the resistance to targeted therapies. In this work, we investigated whether the variant allele frequencies (VAFs) of ALK fusions can help assess ITH and predict targeted therapy efficacy. Through the application of next-generation sequencing (NGS), 7.2% (326/4548) of patients were detected to be ALK positive. On the basis of the adjusted VAF (adjVAF, VAF normalization for tumor purity) of four different threshold values (adjVAF < 50%, 40%, 30%, or 20%), the association of ALK subclonality with crizotinib efficacy was assessed. Nonetheless, no statistical association was observed between median progression-free survival (PFS) and ALK subclonality assessed by adjVAF, and a poor correlation of adjVAF with PFS was found among the 85 patients who received first-line crizotinib. Results suggest that the ALK VAF determined by hybrid capture-based NGS is probably unreliable for ITH assessment and targeted therapy efficacy prediction in NSCLC.

Prognostic Predictive Value of ITPKB Mutation's Variant Allele Frequency in Diffuse Large B-cell Lymphoma / 肿瘤防治研究

Objective To investigate the correlation between ITPKB mutation's variant allele frequency (VAF) and prognosis of diffuse large B-cell lymphoma (DLBCL). Methods This study included 155 patients with DLBCL initially diagnosed in the People's Hospital of Xinjiang Uygur Autonomous Region from June 2014 to December 2020. Paraffin-embedded tumor tissue specimens were obtained, and tumor tissue DNA was extracted. A total of 475 hotspot genes including ITPKB were detected by the next generation sequencing to analyze the relationship of the VAF of high-frequency mutant gene with progression-free survival (PFS) and overall survival (OS). Results The mutation frequency of ITPKB was 18.71%. The PFS was significantly shorter in the patients with ITPKB mutations than in those without mutations (37 months vs. 108 months; HR=1.643, 95%CI: 0.920-2.934, P=0.093). The R-language based web tool was used to find the best VAF cutoff to differentiate prognosis. The patients were divided into two groups (VAF High vs. VAF Low+Wt) according to their VAF values. The optimal VAF threshold for ITPKB was 27.48% (HR=3.480, 95%CI: 1.70-7.13, P=0.00027). Multivariate Cox analysis was conducted using clinical indicators such as age, gender, COO classification, IPI, and LDH, and the results showed that PFS was associated with high ITPKB VAF (≥28%) (HR=3.592, 95%CI: 1.738-7.425, P < 0.001) which was an independent adverse predictor of PFS. Conclusion The high load of ITPKB mutation is an independent risk factor for the PFS of patients with DLBCL, and the VAF of ITPKB mutation has a prognostic predictive value for patients with DLBCL.