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MINI 27 - Biology and Other Issues in SCLC (ID 152)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Small Cell Lung Cancer
- Presentations: 1
MINI27.11 - Comprehensive Mutation Analysis of Never-Smokers with Small Cell Lung Cancer (SCLC) (ID 3135)
16:45 - 18:15 | Author(s): H. Won
Although most patients with SCLC are current or former smokers, this disease has been reported in never-smokers. In our prospective genomic profiling of SCLC patients, we have identified four never-smokers. Here, we report next generation sequencing (NGS) results for these four SCLC patients and describe how they differ from those of smokers.
We are evaluating pathologically confirmed SCLC tumors in patients undergoing treatment. Formalin-fixed, paraffin-embedded surgical resections, core biopsies, and fine needle aspirates are being evaluated using a targeted, hybrid capture-based, NGS assay, MSK-IMPACT, which identifies single nucleotide variants, indels, and copy number alterations in 341 cancer-associated genes. We determined never-smoking status prospectively: all smoked <100 cigarettes in their lifetime. Clinical data on stage [extensive (ES), limited (LS)], treatment, and response were collected.
Four never-smokers have been identified within the 50 patient samples that have undergone NGS evaluation thus far. The median age at diagnosis of the four never-smokers is 58 (range, 47-75); 50% are male; and one presented with LS-SCLC. None of these four patients developed SCLC as acquired resistance to EGFR tyrosine kinase inhibitors after treatment for EGFR-mutant lung cancers. The tumors from the four never-smokers displayed a median of 3 non-synonymous somatic mutations, while those from moderate (<20 pack years) and heavy (20+ pack years) smokers contained 4.5 and 8 mutations, respectively (P<0.05). None of the four never-smoker samples contained smoking associated G-to-T transversions (see Table). Inactivation of RB1 and TP53 occurred in 75% and 50% of the samples, respectively. Only patient 4 had platinum-refractory disease. The median survival of these patients was 20.7 months (range, 17 to 25).
Sample Gene altered Alteration Present Protein Alteration Base Pair Alteration Patient 1 PHOX2B Missense Mutation P82L G-to-A NOTCH1 Frame-Shift Insertion P2485fs RB1 Splice Site R500_splice G-to-A TP53 Frame-Shift Deletion V218fs TP53 Frame-Shift Deletion V73fs TERT Amplification Patient 2 CBL Missense Mutation C401S G-to-C GNAS Missense Mutation M102V A-to-G MYCL Amplification Patient 3 TP53 Nonsense Mutation R342 G-to-A RB1 Frame-Shift Insertion T197fs CDKN2C Amplification MYCL Amplification Patient 4 RB1 Nonsense Mutation C666 ETV1 Amplification
Using a targeted NGS assay, we have shown that the molecular characteristics differ between never-smokers and smokers, while the majority of the tumors demonstrate RB loss. Whole exome sequencing of the tumors from these never-smokers is underway. Ongoing comprehensive, multiplexed genotyping is needed to fully characterize the molecular diversity of SCLC in this unique population.
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P2.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 234)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
P2.04-050 - Basaloid Squamous Cell Cancers Arising from the Lung: Next Generation Sequencing Reveals PTCH1 Mutations in the Hedgehog Pathway (ID 3211)
09:30 - 17:00 | Author(s): H. Won
Basaloid squamous cell lung cancers are a defined variant of non-small cell lung cancers associated with a high mitotic count and rapid clinical progression. Due to its morphologic similarities with basal cell carcinoma of the skin, distinguishing between the two can be difficult. We sought to define the molecular characteristics of basaloid squamous cell cancers that were clinically defined as possible lung primaries in an effort to aid in the diagnosis of this disease.
We reviewed a total of 179 patients who were diagnosed with squamous cell lung cancers and had undergone tumor next generation sequencing at Memorial Sloan Kettering. Through the MSK-Integrated Mutation Profiling for Actionable Cancer Targets (MSK-IMPACT), the illumina HiSeq platform was used to detect 341 potentially actionable genetic alterations, including single base substitutions, indels, copy number alterations and selected gene fusions. Data on clinicopathologic characteristics, smoking history were reviewed, and their mutational profile described.
A total of 6 of 179 (2%) patients with squamous cell lung cancers were found to have basaloid features. Of the 6 patients with basaloid features, 5 (83%) were men, 2 (33%) were never-smokers, 6 (100%) were white Caucasians, 3 (50%) had resected lung specimens, and 2 (33%) presented with stage IV disease. Three cases (50%) had protein patched homolog 1 (PTCH1) mutations in the hedgehog pathway (H652Y, V1057splice, V579fs), identical to those found in basal cell carcinoma of the skin. Two of these patients had a history of basal cell carcinoma of the skin, raising the possibility of metachronous metastatic basal cell carcinoma of the skin. One patient had no such history of basal cell skin cancer.
Basaloid squamous cell cancers that appear to arise from the lung frequently harbor PTCH1 mutations. Metachronous metastatic basal cell carcinoma of the skin needs to be considered as a possibility in patients with a history of superficial skin lesions. Patients diagnosed with these basaloid cancers that harbor PTCH1 mutations, whether from skin or lung origin, may benefit from hedgehog pathway inhibitors such as vismodegib.