As the correlation between high EGFR L858R levels and reduced response to osimertinib was unexpected, we next assessed whether high levels of mutant EGFR were associated with activation through heterodimerization of other receptor tyrosine kinases (RTKs), which is a known mechanism of resistance to anti-EGFR treatment in lung cancer [35]. The gene discussed is NTRK1; the disease is lung carcinoma.