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MINI 30 - New Kinase Targets (ID 157)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
MINI30.09 - Clinical Response to Entrectinib in a Patient with NTRK1-Rearranged Non-Small Cell Lung Cancer (NSCLC) (ID 2913)
18:30 - 20:00 | Author(s): A.J. Iafrate
Chromosomal rearrangements involving neurotrophic tyrosine kinase 1 (NTRK1) occur in less than 1% of NSCLCs. Cell-based assays have demonstrated that NTRK1 rearrangement leads to expression of an oncogenic TrkA fusion protein. While inhibition of TrkA in preclinical models reduces TrkA auto-phosphorylation and cell proliferation, the clinical activity of TrkA inhibitors in NSCLCs harboring an NTRK1 fusion is not known. Entrectinib (RXDX-101) is an orally available tyrosine kinase inhibitor of TrkA, TrkB, TrkC, ROS1, and ALK, with IC50 values for kinase inhibition ≤ 2 nM.
We used an anchored multiplex polymerase chain reaction (AMP) assay to screen for NTRK1 rearrangements (Zheng et al., Nature Medicine 2014). Among over 663 NSCLC cases screened, we identified one positive case in which the 3’ end of SQSTM1 exon 6 was fused to the 5’ end of NTRK1 exon 10, leading to an SQSTM1-NTRK1 fusion transcript. We enrolled the patient onto the Phase 1 dose escalation study of entrectinib in adult patients with locally advanced or metastatic tumors (NCT02097810). The dose of entrectinib was 400 mg/m (750 mg) once daily. We assessed safety of entrectinib and response to treatment using RECIST 1.1.
The patient is a 46 yo male with a 30 pack year smoking history who was first diagnosed with metastatic NSCLC in November 2013. Prior therapies included carboplatin/pemetrexed, pembrolizumab, docetaxel, and vinorelbine. At the time of study enrollment, the patient had an ECOG performance status of 2 and required supplemental oxygen at a rate of 3 liters per minute by nasal cannula. He reported significant pain and dyspnea due to widely metastatic disease, including a large left hilar mass narrowing the left upper lobe bronchus and obstructing the left lower lobe bronchus, extensive and palpable neck and chest lymphadenopathy, and a palpable expansile left chest wall mass. Staging head CT also revealed numerous (15 to 20) asymptomatic brain metastases measuring up to 1.7 cm that had not been previously treated. The patient was started on entrectinib and tolerated the study medication well, with one adverse event of grade 1 dysgeusia, which resolved after two weeks. Within three weeks of starting treatment, the patient reported resolution of dyspnea and pain, and improvement in energy and appetite. He no longer required supplemental oxygen and all sites of palpable disease had improved or resolved. At four weeks of treatment, restaging CT scans demonstrated a partial response by RECIST of -47%, with significant regression or resolution of lymphadenopathy, reduction in size of the chest wall mass, and marked reexpansion of the left lung. Restaging of the CNS by head CT demonstrated near complete resolution of previously visualized brain metastases.
In a heavily pre-treated patient with NSCLC harboring an NTRK1 gene fusion, entrectinib therapy resulted in rapid clinical improvement and a radiologic partial response at 4 weeks with minimal toxicity. This preliminary report suggests that entrectinib may be an effective therapy for patients with NTRK1-rearranged NSCLC.
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