A total of 291 patients diagnosed with lung cancer and were analyzed by both NGS and FISH methods. Among them, 63 (21.6%) patients were treated according to the molecular testing and followed up all the time. The clinical and pathological features of patients with Lung Cancer were summarized in Table 1. There were 23 males (36.5%) and 40 females (63.5%), 20.6% (13/63) had a smoking history, and 22.2% (14/63) were over 65 years old. The median age was 57 years (ranged from 31 to 76 years). There were 60 patients with Adenocarcinoma (94%), 1 with Squamous (1%), and 2 patients with NSCLC (5%).
PFS correlated with EGFR mutation abundance after EGFR-TKI therapy
The median PFS was 10.0 months (range, 1.0-33.0 months), with an overall disease control rate of 42.4%. In order to establish the accurate cutoff value for distinguishing EGFR mutation abundance and thus providing useful evidence for clinical practice, combining the median PFS data of patients given EGFR-TKI orally were analyzed by stratification.
stratified analyses were conducted by combining the median PFS data of patients given EGFR-TKI orally. We respectively tried to use 10%, 20%, 30%, 40%, or 50% as the cutoff values to analyze the medium PFS of the high and low abundance groups. The results revealed that when 10%, 20%, or 30% were used as the cutoff values, the medium PFS achieved a statistically significant therapeutic effect in > 10%, 20%, 30% compared to < 10%, 20% and 30% mutation abundances, respectively (Supplementary Table 1). The medium PFS was most significant (11.0 months vs 8.0 months) when EGFR mutation abundance value of 25% was used as the cutoff value. Although the median PFS was increased initially with an increase in the abundance of EGFR mutation, the median PFS did not continue to increase when the mutation abundance increased more than 30%. Further, we estimated the accurate cut-off value of EGFR mutation abundance by ROC analysis in 63 patients. We found that the cut-off value for it was 28.86% and the area under the curve (AUC) were 0.571 (0.426-0.716) for EGFR mutation abundance (Figure 1A). When the cut-off value of the abundance of EGFR mutations was ≥ 28.86%, the median of mutation abundance was about 40% (Figure 1B), and Kaplan-Meier analysis showed that cut-off value of 28.86% was no significant difference between PFS duration and EGFR mutation abundance (Figure 1C). Simultaneously, we investigated the difference in clinical efficacy between patients with EGFR mutation abundance < 28.86% and ≥ 28.86%, and found that patients with EGFR mutation abundance ≥ 28.86% had slightly higher ORR and similar DCR (Figure 1D-E).
PFS correlated with aneuploidy status after EGFR-TKI therapy
Simultaneously, all 63 cases also received FISH assessment for Aneuploidy status. The mPFS of euploid patients was 9.0 months (40 cases), and that of patients with aneuploidy was 10.0 months (23 cases) (Figure 2A). To further investigate whether euploidy and aneuploidy affected patient’s PFS, Kaplan-Meier analysis showed no significant difference between euploid and aneuploid patients (Fig. 2B). Furthermore, we explored the dissimilitude of clinical efficacy between euploid and aneuploid patients, and found a higher ORR and DCR displayed in euploid patients. The ORR of euploid and aneuploid patients were 7.7% and 0%, and the DCR were respectively 51.3%, 25.0% (Figure 2C-D). The results showed that the PFS of patients diagnosed as euploidy was actually higher than that of patients diagnosed with aneuploidy, and was related to both ORR and DCR, giving a clue that patients diagnosed with euploidy had a better clinical efficacy.
Association among aneuploidy status, EGFR mutation abundance and clinical efficacy
To further elucidate whether tumor aneuploidy status and the abundance of EGFR mutations together affect PFS, there are significant differences both aneuploidy status and EGFR mutation abundance in 63 patients. The median of the abundance of EGFR mutations in patients with euploidy was 25.51%, while that in aneuploid patients was 28.59% (Figure 3A). Two-way analysis of variance was also used to assess the effects of EGFR mutation abundance and tumor aneuploidy status on patients’ PFS. In patients with EGFR mutation abundance less than 28.86%, euploid patients was slightly more significant than aneuploid patients. However, in patients with EGFR mutation abundance more than 28.86%, there was not significant difference between euploid and aneuploid patients (Figure 3B). When the EGFR mutation abundance was less than 28.86%, the mPFS of patients with euploidy and aneuploidy were 9 and 11 months, respectively. when patients with the EGFR mutation abundance was more than 28.86%, the mPFS of patients were 11 and 10 months. We also assessed the dissimilitude of clinical efficacy between both EGFR mutation abundance and aneuploidy status. Euploid patients had higher ORR and DCR than aneuploid patients, regardless of EGFR mutation abundance (Figure 3C-D). Next, we also conducted univariate analysis for the general characteristic of age, gender, smoking history by Kaplan-Meier survival analyses. The results showed that these factors were not associated with the median PFS after EGFR-TKI (Supplementary Table 2).