Prolonged Disease Control Despite ALK Inhibitor Discontinuation in Advanced ALK-Positive NSCLC.

Introduction: Case description: We report three different patients with advanced ALK-positive NSCLC seen at our institute, who had Discussion: Shorter time to progression on TKI, presence of symptoms with disease progression or central nervous system/pleural metastasis have been previously linked with development of flare, although this was not seen in our case series. Tumour response at the time of treatment discontinuation, line of therapy, overall disease burden, fusion variant and co-alteration status can affect the prognosis of these patients after ALK TKI cessation. In particular, variant 1 and wild-type TP53 status may be a suitable patient population for dose optimisation strategies. Intermittent TKI dosing strategies may help to avoid acquiring resistance mutations and prevent long-term treatment toxicities. Conclusion: It is important for clinicians to identify patients at risk for developing disease flare on TKI discontinuation to improve outcomes. Intermittent TKI dosing strategies require further investigation. LEARNING POINTS: Patients who develop disease flare after cessation have poor survival and worse outcomes.Certain phenotypic and molecular characteristics of the tumour may help clinicians identify which patients are likely and which are unlikely to develop disease flare on TKI discontinuation.Advanced ALK-positive NSCLC with variant 1 and wild-type TP53 may be a suitable patient population for intermittent TKI dosing investigations.