Background: Despite development of several next-generation tyrosine kinase inhibitors (TKIs), crizotinib remains one of the first-line treatment options for advanced ALK-positive NSCLC and is widely used in situations where next-generation TKIs aren't yet approved or economically inaccessible. However, the pattern of failure and clinical value of radiotherapy in metastatic crizotinib-treated ALK-mutant lung cancer, with or without baseline brain metastases (BBM), are largely unknown.
Methods: Consecutive crizotinib-treated NSCLC patients with adequate imaging and measurable disease were retrospectively enrolled. Disease progression in original sites (primary/metastatic), new sites, or both, are classified as original failure (OF), distant failure (DF) and ODF, respectively. Progression free survival, from crizotinib initiation to the first disease progression, and from that to the second disease progression, were calculated as PFS1 and PFS2.
Results: Ninety-three patients were identified. With a median follow up of 22.0 (range, 2.0-72.0) months, 52 patients had crizotinib-treatment failure. The frequencies of OF, ODF, and DF, were 50.0, 26.9, and 23.1%, respectively. Histology, primary tumor size and presence of BBM, were independently associated with OF, using competing risks analyses. The brain was the most common site of initial disease progression. Patients with BBM had a significant higher possibility developing multiple-progressive lesions in the brain (p = 0.002). Importantly, four of the ten patients who had baseline oligo-metastatic cranial disease but didn't receive upfront brain radiation, developed multiple-progressive disease in the brain. Brain radiation before crizotinib could alter the disease failure patterns and improve PFS1 among patients with BBM (p = 0.006). Extracranial radiation was efficient in controlling symptoms but it was not associated with PFS1 (p = 0.223), and the majority of patients were eligible for salvage radiotherapy upon disease progression to crizotinib. By the time of data cut-off, 28 patients had second disease progression, with a median PFS2 of 7.0 (95% CI 5.4-8.6) months and salvage radiotherapy significantly prolonged PFS2 (p = 0.003). Additionally, patients receiving any radiotherapy during their treatment course had a significant longer overall survival (p = 0.048).
Conclusions: Among patients with baseline oligo-metastatic brain lesions which are suitable for stereotactic radiosurgery, upfront brain radiotherapy provides considerable clinical benefits. While, extracranial radiation may be deferred in asymptomatic patients with multiple-metastatic lesions.
Keywords: ALK; Brain metastases; Non-small cell lung cancer; Pattern of failure; Radiotherapy; Survival.