ALK-positive disease is characterized by the presence of ALK gene rearrangements that encode driver fusion
oncoproteins. EML4-ALK fusion is regarded as the most common type in advanced nonsmall cell
lung cancers. STRN-ALK is a novel ALK fusion partner in NSCLC and is considered sensitive to targeted
therapy. However, there was no study regarding effective
therapy for EML4-ALK and STRN-ALK double fusion variants in EGFR-resistant mutant
lung cancer. TP53, RB1, and EGFR exon 21 L858R were found in
tumor tissues and plasma from patients with capture-based NGS. After 3 months of
gefitinib treatment, an NGS of plasma
circulating tumor DNA showed that all variants disappeared significantly, and the
tumor mass regressed on CT. However, after 10 months, the patient developed drug resistance and the disease progressed with the appearance of new metastatic lesions in the liver and bones. A repeated NGS test revealed EGFR exon20 T790M and the appearance of a novel double-fusion EML4-ALK and STRN-ALK. A combined therapeutic regimen of
crizotinib plus
osimertinib showed a promising prognosis confirmed with lung CT scans showing stable lesions without any new
metastasis. Moreover, a subsequent genotype by NGS also showed the disappearance of STRN-ALK and EGFR exon20 T790M. The therapeutic efficacy of
crizotinib plus
osimertinib on EML4-ALK and STRN-ALK double-fusion variant in patients with EGFR-resistant mutant
lung cancer may provide a supportive reference for the patients with such genetic alteration.