PMC4773904_01
Acquired Resistance to Lorlatinib and Resensitization to Crizotinib. Panel A shows the various treatments the patient received for metastatic anaplastic lymphoma kinase (ALK)-rearranged non-small-cell lung cancer as well as the duration of each treatment. Panel B shows computed tomographic (CT) images of the patient's metastatic liver disease before she received lorlatinib, during the time she had a response to lorlatinib, when the disease subsequently relapsed at 9 months, and during the patient's second response to crizotinib therapy. A radiologic second response to crizotinib was noted on the first restaging CT obtained after 8 weeks of treatment. Shown is the patient's second response after she had received crizotinib for 12 weeks. Panel C shows serial monitoring of total bilirubin levels and alkaline phosphatase levels before and after retreatment with crizotinib. To convert values for bilirubin to micromoles per liter, multiply by 17.1. The starting dose of crizotinib was 250 mg once daily, which was increased to 250 mg twice daily once the patient's liver-function tests showed improvement. Crizotinib treatment was initiated on day 1. Arrowheads indicate intermittent administration of low-dose vinorelbine, which was eventually discontinued because of neutropenia. The relative dose intensity (the proportion of administered doses relative to planned doses) of vinorelbine was 0.54. Panel D shows the results of fluorescence in situ hybridization (FISH) assays of tumor cells for ALK (left) and MET (right). The standard break-apart ALK FISH assay was used to screen the lorlatinib-resistant sample for ALK rearrangement and gene amplification. Split signals (white arrows) were observed in 30% of the cells, a finding consistent with ALK rearrangement; no amplification of ALK was detected. A dual-color FISH assay with a C-MET probe (Repeat-Free Poseidon C-MET [7q31] probe, Kreatech) and a copy-number control probe (centromere 7 [CEP7], Abbott-Vysis) were used to screen for MET amplification. The MET-to-CEP7 ratio (i.e., the ratio of red signals to cyan signals) was 1.0, indicating no amplification. Amplification of C-MET would appear as more red signals than cyan signals. Panel E shows clonal evolution of resistance to ALK inhibitors in the patient. This model is based on an analysis of whole-exome sequencing of pretreatment and resistant biopsy samples. A founder ALK C1156Y subclone was detectable at low frequency in the pretreatment tumor specimen. With crizotinib therapy, this subclone expanded to 50% of the tumorcell population and led to the patient's relapse. Lorlatinib was effective against the crizotinib-resistant tumor, but the C1156Y subclone acquired a second ALK mutation, L1198F. The double-mutant subclone (C1156Y-L1198F) was insensitive to lorlatinib and became the dominant subclone in the relapsed tumor. Selected mutations identifying each subclone are shown. Biopsies were performed where indicated. No biopsy was performed when the patient received intervening therapies between crizotinib and lorlatinib, so the proportion of subclones shown during this time period are extrapolated from the post-crizotinib sample.
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The first restaging CT after 5 weeks of treatment showed a 41% reduction in tumor burden (Fig. 1B). CT showed markedly worsening disease with nearly confluent metastatic lesions in the liver, splenomegaly, and ascites (Fig. 1B). Over the next 5 days, she had further clinical deterioration and impending liver failure, with a total bilirubin level increasing to 4.8 mg per deciliter (82 mumol per liter) (Fig. 1C). The patient had a rapid and dramatic clinical improvement, with resolution of her liver failure (Fig. 1C). Serial restaging CT showed a clinically significant radiologic response that lasted almost 6 months (Fig. 1B).