[Role of the Sonic Hedgehog pathway in thoracic cancers]

A Sonic Hedgehog Pathway Score to Predict the Outcome of Resected Non-Small Cell Lung Cancer Patients

BACKGROUND

Mutations and deregulations in components of the Hedgehog (Hh) pathway have been associated with cancer onset and tumor growth in different malignancies, but their role in non-small cell lung cancer (NSCLC) remains unclear. This study aims to investigate the expression pattern of the main components of the Hh pathway in tumor and adjacent normal tissue biopsies of resected NSCLC patients.

METHODS

The relative expression of GLI1, PTCH1, SHH, and SMO was analyzed by quantitative polymerase chain reaction (PCR) in a cohort of 245 NSCLC patients. Results were validated in an independent cohort of NSCLC patients from The Cancer Genome Atlas (TCGA).

RESULTS

We found that SMO and GLI1 were overexpressed in the tumor compared with normal-paired tissue, whereas PTCH1 and SHH were underexpressed. In addition, patients with higher expression levels of PTCH1 presented better outcomes. A gene expression score, called the Hedgehog Score, was calculated using a multivariable model including analyzed components of the Hh signaling pathway. NSCLC patients with a high Hedgehog Score had significantly shorter relapse-free survival (RFS) and overall survival (OS) than patients with a low score, especially at stage I of the disease. Similarly, patients in the adenocarcinoma (ADC) subcohort had shorter RFS and OS. Multivariate Cox analysis exhibited that the Hedgehog Score is an independent prognostic biomarker for OS in both the entire training cohort and the ADC subcohort. The Hedgehog Score was validated in an independent cohort of NSCLC patients from TCGA, which confirmed its prognostic value.

CONCLUSIONS

Our results provide relevant prognostic data for NSCLC patients and support further studies on the Hh pathway.

Sonic Hedgehog Pathway as the Prognostic Marker in Patients with Extensive Stage Small Cell Lung Cancer

PURPOSE

Sonic hedgehog (Shh) signaling pathway is known to play a crucial role in carcinogenesis in various malignancies, including lung cancer regarding tumorigenesis, angiogenesis, and cellular differentiation. The aim of this study was to investigate the value of components of Shh pathway as a prognostic marker in extensive stage small cell lung cancer (ES-SCLC) patients.

MATERIALS AND METHODS

We retrospectively analyzed data of 36 patients who were diagnosed with ES-SCLC between 2008 and 2012 at a single center. We performed immuo-histochemistry for glioma-associated oncogene homolog zinc finger protein 1 (Gli1), patched, Shh, and Ptch-mediated repression of smoothened (Smo) proteins using formalin-fixed, paraffin-embedded tissue derived from primary tumors. We then conducted survival analysis to evaluate the prognostic impact of these markers.

RESULTS

All 36 patients received platinum-based doublet chemotherapy. The median progression free survival and median overall survival were 6.9 months [95% confidence interval (CI), 6.5-7.3] and 11.7 months (95% CI, 9.1-14.3), respectively. The overall response rate was 84%. Of the 36 tissue specimens examined, over-expression of Gli1, Patched, Shh, and Smo was found in 12 (33.3%), five (13.9%), five (13.9%), and six (16.7%) cases, respectively. We found that high expression of Shh was associated with worse progression free survival (6.3 vs. 7.6 months, p=0.005) and overall survival (9.2 vs. 12.0 months, p=0.039) by both univariate and multivariate analyses, whereas other markers were not related to patient prognosis.

CONCLUSION

A high proportion of small cell lung cancer tumors express proteins related to Shh pathway, and over-expression of Shh is correlated with poor prognosis.

Vismodegib or cixutumumab in combination with standard chemotherapy for patients with extensive-stage small cell lung cancer: A trial of the ECOG-ACRIN Cancer Research Group (E1508)

BACKGROUND

Preclinical targeting of the hedgehog pathway by vismodegib and of insulin-like growth factor 1 receptor by cixutumumab enhances the efficacy of chemotherapy and also demonstrates activity against the tumor cell fraction responsible for disease recurrence in small cell lung cancer.

METHODS

Patients with newly diagnosed extensive-stage small cell lung cancer (SCLC-ED) were randomized to receive four 21-day cycles of cisplatin and etoposide alone (cisplatin at 75 mg/m(2) on day 1 and etoposide at 100 mg/m(2) on days 1-3; arm A) or in combination with either vismodegib (150 mg/d by mouth; arm B) or cixutumumab (6 mg/kg/wk intravenously on day 1; arm C). The primary endpoint was progression-free survival (PFS). Circulating tumor cells (CTCs) were isolated/enumerated with the Veridex CellSearch platform at the baseline.

RESULTS

One hundred fifty-two eligible patients were treated. Patient demographics and disease characteristics were well balanced between the 3 arms except for the higher rate with a performance status of 0 in arm B (P = .03). The median PFS times in arms A, B, and C were 4.4, 4.4, and 4.6 months, respectively; the median overall survival (OS) times were 8.8, 9.8, and 10.1 months, respectively; and the response rates were 48%, 56%, and 50%, respectively. None of the comparisons of these outcomes were statistically significant. The median OS was 10.5 months for those with low CTC counts (≤100/7.5 mL) at baseline and 7.2 months for those with high CTC counts (hazard ratio, 1.74; P = .006).

CONCLUSIONS

There was no significant improvement in PFS or OS with the addition of either vismodegib or cixutumumab to chemotherapy in patients with SCLC-ED. A low baseline CTC count was associated with a favorable prognosis. Cancer 2016;122:2371-2378. © 2016 American Cancer Society.