The primary purpose of the ALKTERNATE clinical trial was to evaluate the efficacy, safety and feasibility of alternating lorlatinib and crizotinib for the treatment of ALK-rearranged advanced NSCLC, and to provide information on the potential to delay the emergence of drug resistance as compared to continuous lorlatinib therapy alone. The study found that alternating crizotinib and lorlatinib could be done safely and did not compromise the control of cancer compared to usual care. However, since the trial commenced, lorlatinib has become first line standard of care therapy for ALK+ NSCLC. Blood samples collected from patients during treatment on the ALKTERNATE clinical trial revealed that every ALK+ NSCLC patient is different, with no one clear mechanism identified for resistance to treatment.