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Robin Guo
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MA12 - New Frontiers from Pathology to Genomics (ID 138)
- Event: WCLC 2019
- Type: Mini Oral Session
- Track: Mesothelioma
- Presentations: 1
- Now Available
- Moderators:Prasad S Adusumilli, Francisco Perez Ochoa
- Coordinates: 9/09/2019, 14:00 - 15:30, Melbourne (1991)
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MA12.10 - Novel Germline Mutations in DNA-Damage Repair and DNA Replication Identified in Patients with Malignant Pleural Mesothelioma (MPM) (Now Available) (ID 1419)
14:00 - 15:30 | Presenting Author(s): Robin Guo
- Abstract
- Presentation
Background
Recent efforts to characterize the germline genetic landscape of MPM have uncovered a surprising prevalence of pathogenic variants in DNA-damage sensing and repair genes. Increasingly, next-generation sequencing has helped bring new insight into critical mutations or pathways involved in the development of MPM. Additionally, observations from these studies could direct new screening, prevention, and therapeutic approaches for patients and families.
Method
With IRB approval, we performed deidentified analysis on 87 additional cancer-predisposing genes on our NGS platform among patients with MPM previously consented to a BAP1 germline testing protocol. Additionally, germline variants in an additional 380 genes associated with somatic alterations in cancer, but not associated with hereditary cancer predisposition, were screened for loss of function variant or pathogenic entries in ClinVar. All variants were reviewed according to the American College of Medical Genetics and Genomics and Association for Molecular Pathology consensus guidelines. Founder mutations were excluded. Clinicopathologic information was also collected. Comparisons were done using Fisher’s exact test. P values <0.05 were considered significant.
Result
Of 88 patients with MPM analyzed, 11% (10/88) had pathogenic variants. Clinical characteristics such as age, sex, histology, and self-reported asbestos exposure, were similar between patients with and without pathogenic variants (Table 1). Pathogenic variants previously unreported in mesothelioma were identified: MSH3 1/88 (1%; 95% CI: 0-7%), BARD1 1/88 (1%; 95% CI: 0-7%), and RECQL4 2/88 (2%; 95% CI: 0-8%). We also identified pathogenic variants previously associated with mesothelioma: BAP1 in 3/88 (3%; 95% CI: 1-10%), BRCA2 1/88 (1%; 95% CI: 0-7%), and MRE11A 1/88 (1%; 95% CI: 0-7%). One patient had a potentially pathogenic alteration in SHQ1, which has not been associated with a heightened susceptibility to cancer. Patients with germline pathogenic variants were more likely to have more than 2 first-degree family members with cancer compared to those without germline mutations (40% vs 13%; p = 0.049).
Conclusion
While the overall incidence of germline mutations identified is similar to prior reports, we identified germline pathogenic alterations in three DNA damage repair and replication genes not previously reported in mesothelioma. Furthermore, we describe a novel germline alteration in SHQ1, which has not been reported with hereditary cancer predisposition. Whether these variants increase the risk of mesothelioma is still under investigation, but given the high rate of germline pathogenic variant in individuals with pleural mesothelioma, germline testing for hereditary cancer susceptibility should be considered in all patients with MPM.
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P1.14 - Targeted Therapy (ID 182)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Targeted Therapy
- Presentations: 1
- Now Available
- Moderators:
- Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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P1.14-50 - A Phase 2 Trial of Cabozantinib in ROS1-Rearranged Lung Adenocarcinoma (Now Available) (ID 2753)
09:45 - 18:00 | Presenting Author(s): Robin Guo
- Abstract
Background
To date, no ROS1 inhibitor is approved for the treatment of ROS1-rearranged lung cancers after progression on crizotinib. Progression on crizotinib can be mediated by the acquisition of ROS1 kinase domain mutations (e.g. ROS1G2032R or ROS1D2033N). Cabozantinib is a highly potent ROS1 tyrosine kinase inhibitor that has superior activity over lorlatinib against these mutations. We evaluated the activity of cabozantinib in patients with ROS1-rearranged lung cancers on a phase 2 trial.
Method
In this single-center, open-label, Simon two-stage, phase 2 study, eligible patients had ROS1-rearranged unresectable/metastatic non-small cell lung cancer, a Karnofsky performance status >70%, and measurable disease. ROS1 fusion was identified by local testing in a CLIA-compliant environment. Cabozantinib was dosed at 60 mg once daily. The primary endpoint was objective response (RECIST v1.1). In the first stage of this trial, 1 response was required to move to the second stage. Secondary endpoints included safety.
Result
Six patients received cabozantinib in the ongoing first stage of this study. All patients had >1 prior ROS1 inhibitor. The median age was 59 years; all were never smokers. The best response to therapy was: 1 partial response (-92%, confirmed), 1 unconfirmed partial response (-31%), and 4 stable disease. All patients had disease regression (-7 % to -92%); no patients had primary progressive disease. The only patient with a confirmed partial response was a patient whose cancer acquired a ROS1D2033N solvent front mutation after crizotinib. None of the other five ROS1 inhibitor pre-treated patients (who did not have a confirmed response) had a known on-target acquired resistance mutation in their cancer. After progression on cabozantinib (9.1 months after therapy initiation), the patient whose cancer harbored the ROS1D2033N mutation acquired a METD1228N kinase domain mutation on paired sequencing of pre-cabozantinib and post-progression tumor. The most common grade 3 treatment-related adverse events were hypertension (50%), and mucositis, palmar-plantar erythrodysesthesia, and hypophosphatemia (each in 17%). Most patients (83%) required a dose reduction.
Conclusion
Cabozantinib can re-establish disease control in ROS1-rearranged lung cancers after progression on a prior ROS1 inhibitor. The first stage of this ongoing trial met its prespecified endpoint for efficacy to move into the second stage. Response was only observed in the setting of a known ROS1 kinase domain resistance mutation.
