Intercalated Treatment Following Rebiopsy Is Associated with a Shorter Progression-Free Survival of Osimertinib Treatment

Real-world osimertinib pretreatment experience in patients with epidermal growth factor receptor T790M mutation-positive locally advanced or metastatic non-small cell lung cancer

Osimertinib has demonstrated efficacy in patients with epidermal growth factor receptor (EGFR) T790M-positive non-small cell lung cancer (NSCLC) in clinical trials. However, real-world data on its effectiveness remain scarce. Taiwanese patients with T790M-positive locally advanced or metastatic NSCLC and progressive disease following treatment with at least one EGFR tyrosine kinase inhibitor (TKI) were enrolled from the osimertinib early access program. Of the 419 patients (mean age, 63 years; female, 67%), 53% were heavily pretreated (≥ third-line [3L]), making osimertinib a fourth-line (4L) intervention. The median progression-free survival (PFS) was 10.5 months (95% confidence interval [CI]: 8.95-11.41); the 18-month PFS rate was 26.5%. The median overall survival (OS) was 19.0 months (95% CI: 16.30-20.95); the 24-month OS rate was 40.9%. The objective response rate was 32.46%, and the disease control rate was 86.38%. The median time to treatment discontinuation of osimertinib monotherapy was 11.9 months (95% CI: 10.49-13.11). Subgroup analyses of median PFS and OS in the chemotherapy combination group vs. the osimertinib monotherapy group yielded no difference. Central nervous system (CNS) metastasis, number of prior lines of therapy, and types of initial EGFR-TKIs did not significantly impact outcomes. The median PFS values were 9.0 (95% CI: 5.18-11.34) and 10.9 (95% CI: 9.18-11.90) months with and without CNS metastasis, respectively, and 10.8 (95% CI: 8.59-12.69), 13.6 (95% CI: 10.89-16.3), and 9.2 (95% CI: 7.8-10.62) months for second-line (2L), 3L, and ≥4L therapy, respectively. In patients who received osimertinib as 2L therapy, the median PFS values in response to prior afatinib, erlotinib and gefitinib treatment were 11.2 (95% CI: 4.85-4.79), 10.5 (95% CI: 8.59-20.26) and 8.7 (95% CI: 7.21-16.79) months, respectively. Overall, real-world data from Taiwan support the clinical benefits of osimertinib in EGFR T790M -positive NSCLC.

Primary Tumor Resection Is Associated with a Better Outcome among Advanced EGFR-Mutant Lung Adenocarcinoma Patients Receiving EGFR-TKI Treatment

OBJECTIVES

The characteristics and efficacy of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) in advanced EGFR-mutant lung adenocarcinoma patients with primary tumor resection (PTR) is not yet clear.

METHODS

We enrolled advanced EGFR-mutant lung adenocarcinoma patients with EGFR-TKI as first-line therapy to access the impact of PTR on the outcomes.

RESULTS

A total of 466 patients were enrolled with 76 patients (16.3%) undergoing PTR; 59 patients recurred after curative surgery, while 17 patients underwent surgery as diagnostic purposes. PTR patients displayed a better performance status, a lower metastatic burden, and much less measurable diseases (30.3 vs. 97.4%, p < 0.001). PTR patients experienced a significantly longer progression-free survival (25.1 [95% CI 16.6-33.7] vs. 9.4 [95% CI 8.4-10.4] months; aHR 0.40 [95% CI 0.30-0.54], p < 0.001) and overall survival (56.8 [95% CI 36.3-77.2] vs. 31.8 [95% CI 28.2-35.4] months; aHR 0.57 [95% CI 0.39-0.84], p = 0.004). Survival advantage was still observed while comparing PTR patients with the better performance and lower metastatic burden subgroup found within the non-resection group. Moreover, the progression-free survival and overall survival of 11 patients who were found having pleural metastases during surgery and underwent PTR plus pleural biopsy, were also longer than those with pure N0--1/M1a-malignant pleural effusion disease in the non-resection group (n = 19) (p < 0.001 and p = 0.002, respectively).

CONCLUSION

PTR was associated with significantly better outcomes in advanced lung adenocarcinoma patients treated with EGFR-TKI. Further studies are needed to evaluate the biological role of PTR among these patients.

Post-Progression Survival in Secondary EGFR T790M-Mutated Non-Small-Cell Lung Cancer Patients With and Without Osimertinib After Failure of a Previous EGFR TKI

BACKGROUND

Osimertinib is effective in non-small-cell lung cancer (NSCLC) with an acquired epidermal growth factor receptor (EGFR) T790M mutation, the most common resistance mechanism to first- and second-generation EGFR tyrosine kinase inhibitors (TKIs).

OBJECTIVES

We aimed to evaluate survival outcome of patients with EGFR-mutant NSCLC who have progressed on previous EGFR TKI therapy.

PATIENTS AND METHODS

Advanced NSCLC patients with EGFR mutation after acquired resistance to first- or second-generation EGFR TKI who received tumor rebiopsy after EGFR TKI failure from 1 January 2012 to 31 December 2017 were reviewed. Patient clinical characteristics, T790M mutation status, and post-progression survival (PPS) were recorded by chart review.

RESULTS

We included 240 patients and the percentage of secondary T790M mutations in first time tissue rebiopsy was 52.9%. 38 of the initial T790M-negative patients received second rebiopsies and 14 (36.8%) of these were T790M positive. The duration between first and second rebiopsy tended to be longer in patients who had T790M mutation in the second biopsy (11.5 vs. 6.9 months, p = 0.043). After EGFR TKI failure, the median PPS of patients who had the T790M mutation and history of osimertinib use was 42.6 months (95% CI 34.6-50.5), compared to 18.0 (95% CI 9.6-26.4) months in T790M-positive patients without a history of osimertinib use, and 18.8 (95% CI 9.3-28.4) months in patients with no T790M mutation (p < 0.0001). Multivariate analysis showed that history of osimertinib use was correlated with improved survival.

CONCLUSIONS

These data further emphasize that osimertinib should be a standard of care in patients with pretreated EGFR T790M-positive NSCLC.

Prior EGFR-TKI Treatment in EGFR-Mutated NSCLC Affects the Allele Frequency Fraction of Acquired T790M and the Subsequent Efficacy of Osimertinib

BACKGROUND

The first (1G) and second (2G) generations of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) show differential inhibitory capacities towards EGFR T790M-mutated non-small-cell lung cancer (NSCLC) cells.

OBJECTIVE

To assess the ratio of the allele fractions of T790M (AF_T790M) to EGFR-activating mutations (AF_mEGFR) in patients treated with 1G and 2G EGFR TKIs who acquired T790M-mediated resistance and to determine the relationship between AF and the later efficacy of osimertinib.

PATIENTS AND METHODS

The efficacy of osimertinib was reviewed for 54 T790M-positive EGFR-mutated NSCLC patients grouped by the generation of prior EGFR TKI use (1G vs. 2G). AF_mEGFR and AF_T790M were determined by QuantStudio digital PCR using tissues obtained upon acquired resistance.

RESULTS

The progression-free survival (PFS; 20.3 vs. 11.6 months, p = 0.031) and the 1-year PFS rate (63.2 vs. 37.5%, p = 0.029) for osimertinib were significantly better for group 1G compared to group 2G. The ratio of AF_T790M to AF_mEGFR in group 1G was significantly higher than in group 2G (46.16 ± 5.40% vs. 25.86 ± 4.25%, p = 0.009). An unbiased analysis revealed three AF-associated clusters (ARCs) suggesting the ratio of AF_T790M to AF_mEGFR correlates with the efficacy of osimertinib. We found all patients in ARC2 having the highest ratio of AF_T790M to AF_mEGFR to have previously been treated with a 1G EGFR TKI and to show the longest osimertinib PFS compared to ARC3 (NR vs. 11.9 months, p = 0.060) and ARC1 (NR vs. 12.4 month, p = 0.045).

CONCLUSIONS

Acquired T790M fraction of EGFR-mutated NSCLC is linked to different generations of prior EGFR TKI use and the later efficacy of osimertinib.