Person:

Suk Heist, Rebecca

Background: To study the association between functional single nucleotide polymorphisms (SNPs) in candidate genes from oxidative stress pathways, and risk of radiation pneumonitis (RP) in patients treated with thoracic radiation therapy (RT) for locally advanced lung cancer (LC).

Methods: We reviewed 136 patients treated with RT for LC between 2001 and 2007, and had prior genotyping of functional SNPs in oxidative stress genes including superoxide dismutase 2 (SOD2; rs4880) and methylenetetrahydrofolate reductase (MTHFR; rs1801131, rs1801133). RP events were retrospectively scored using the Common Terminology Criteria for Adverse Events, version 4.0. Cox proportional hazard regression was performed to identify clinical variables and genotypes associated with risk of grade ≥2 and grade ≥3 RP on univariate and multivariate analysis. P-values were corrected for multiple hypothesis testing.

Results: With a median follow-up of 21.4 months, the incidence of ≥grade 2 RP was 29% and ≥grade 3 RP was 14%. On multivariate analysis, after adjusting for clinical factors such as concurrent chemotherapy, and consolidation docetaxel, and lung dosimetric parameters such as V20 and mean lung dose, MTHFR genotype (rs1801131; AA versus AC/CC) was significantly associated with risk of ≥grade 2 RP (Hazard ratio [HR]: 0.37; 95% confidence interval [CI]: 0.18-0.76; p=0.006, corrected p=0.018) and ≥grade 3 RP (HR: 0.21; 95% CI: 0.06-0.70; p=0.01; corrected p=0.03). SOD2 genotype was not associated with RP.

Conclusions: Our study showed an association between MTHFR genotype and risk of clinically significant RP. Further study of MTHFR-related pathways may provide insight into the mechanisms behind RP.

MET exon 14 alterations are oncogenic drivers of non-small cell lung cancers (NSCLCs).1 These alterations are associated with increased MET activity and preclinical sensitivity to MET inhibition.2 Crizotinib is a multikinase inhibitor with potent activity against MET.3 The antitumor activity and safety of crizotinib were assessed in 69 patients with advanced NSCLCs harboring MET exon 14 alterations in an expansion cohort of a phase 1 study of crizotinib (NCT00585195). The confirmed objective response rate was 32% (95% confidence interval [CI], 21–45) among 65 response-evaluable patients. Objective responses were observed independent of the molecular heterogeneity that characterizes these cancers and did not vary by MET exon 14 alteration splice site region and mutation type, concurrent increased MET copy number, or the detection of a MET exon 14 alteration in ctDNA. The median duration of response was 9.1 months (95% CI, 6.4–12.7). The median progression-free survival was 7.3 months (95% CI, 5.4–9.1). MET exon 14 alteration defines a molecular subgroup of NSCLCs for which MET inhibition with crizotinib is active. These results address an unmet need for targeted therapy in patients with MET exon 14-altered lung cancers and adds to an expanding list of genomically-driven therapies for oncogenic subsets of NSCLC.

Purpose Lung cancer, of which 85% is non–small-cell (NSCLC), is the leading cause of cancer-related death in the United States. We used genome-wide analysis of tumor tissue to investigate whether single nucleotide polymorphisms (SNPs) in tumors are prognostic factors in early-stage NSCLC.

Patients and Methods One hundred early-stage NSCLC patients from Massachusetts General Hospital (MGH) were used as a discovery set and 89 NSCLC patients collected by the National Institute of Occupational Health, Norway, were used as a validation set. DNA was extracted from flash-frozen lung tissue with at least 70% tumor cellularity. Genome-wide genotyping was done using the high-density SNP chip. Copy numbers were inferred using median smoothing after intensity normalization. Cox models were used to screen and validate significant SNPs associated with the overall survival.

Results Copy number gains in chromosomes 3q, 5p, and 8q were observed in both MGH and Norwegian cohorts. The top 50 SNPs associated with overall survival in the MGH cohort (P ≤ 2.5 × 10−4) were selected and examined using the Norwegian cohort. Five of the top 50 SNPs were validated in the Norwegian cohort with false discovery rate lower than 0.05 (P < .016) and all five were located in known genes: STK39, PCDH7, A2BP1, and EYA2. The numbers of risk alleles of the five SNPs showed a cumulative effect on overall survival (Ptrend = 3.80 × 10−12 and 2.48 × 10−7 for MGH and Norwegian cohorts, respectively).

Conclusion Five SNPs were identified that may be prognostic of overall survival in early-stage NSCLC.