Targeting driver mutations in lung cancer with interstitial pneumonia: A nationwide study in Japan.

[INTRODUCTION] Non-small cell lung cancer (NSCLC) patients with comorbid interstitial pneumonia (IP) are at high risk for drug-induced pneumonitis, and previous reports suggest a lower frequency of common driver mutations such as EGFR. This may discourage genetic testing, potentially overlooking prevalent, targetable mutations like KRAS, BRAF, and MET. This study aimed to elucidate the real-world status of genetic testing, the frequency of oncogenic drivers, and the safety and efficacy of targeted therapies in patients with NSCLC and comorbid IP.

[METHODS] This multicenter, retrospective study analyzed 1256 patients with advanced or recurrent NSCLC and comorbid chronic fibrosing IP from 37 Japanese institutions (Registry number: UMIN000055609).

[RESULTS] The rate of any genetic testing was 59.2 % (95 % confidence interval [CI], 56.5-62.0), with multigene testing performed in only 41.0 % (95 %CI, 38.3-43.8). Among patients with NSCLC undergoing multigene testing (N = 515), the most frequent mutations were KRAS (4.7 %; G12C, 1.9 %), followed by EGFR (2.9 %), BRAF V600E (1.6 %), and MET exon 14 skipping (1.6 %). The incidence of drug-induced pneumonitis was 0 % (0/6) for sotorasib, 50 % (4/8) for osimertinib, 33 % (1/3) for alectinib, and 25 % (1/4) for both dabrafenib plus trametinib and tepotinib. Patients with actionable oncogenic drivers receiving targeted therapy had the longest overall survival, followed by those not receiving it, and then driver-negative/unknown patients (median: 39.2, 24.0, and 13.8 months, respectively).

[CONCLUSIONS] Multigene testing is underutilized in this population. While many targeted therapies carry a high risk of pneumonitis, sotorasib appeared relatively safe. Despite the risks, identifying and treating actionable oncogenic drivers may improve survival.