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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
MINI27.13 - Progastrin-Releasing Peptide (ProGRP) as a Biomarker for Clinical Response in Small-Cell Lung Carcinoma (SCLC) (ID 1390)
16:45 - 18:15 | Author(s): X. Zhi
Most cases of small-cell lung cancer (SCLC) are detected at extensive stage, where current guidelines recommend 4-6 cycles of chemotherapy. Although upfront progression to doublet platinum based chemotherapy in SCLC is <20%, current clinical practice often includes treatment monitoring with imaging, mainly with computed tomography, every two cycles. Since the purpose of imaging during treatment is identification of progression (to avoid further exposure to an ineffective but still potentially toxic regimen), we sought to evaluate whether monitoring SCLC patients during treatment with a blood-based biomarker (ProGRP) would correlate with response.
Patients with SCLC treated with mainly standard chemotherapy at six centers worldwide (Europe and China) were included. ProGRP levels from serum or plasma were measured with a fully automated ProGRP assay in a prospective fashion prior to treatment start and repeatedly during treatment. Imaging was done and interpreted according to local guidelines at each institution. Percent change of ProGRP from baseline to the time of maximum response (‘best response’) was correlated with imaging findings, and patients were divided into two groups: Responders (= stable disease [SD] or better) vs. Non-Responders (= progression on scan). The ability of ProGRP to discriminate between Responders and Non-Responders was assessed by sensitivity and specificity.
215 patients with available CT result were included, of whom 145 had received first-line treatment (131 received platinum+VP-16 doublet). Clinical characteristics were as follows: 60.5% male, median age was 62 years, 72.1% were (ex)smokers, 93.5% with Stage IIIB or IV SCLC, and the majority of patients were either Caucasian (59.6%) or Asian (32.6%). Across all lines of treatment, 186/215 (86.5%) had SD or better as best response to treatment. There was a positive trend for higher ProGRP levels with clinical stage at presentation, and in general higher pre-treatment levels in 1[st] line compared to later lines of treatment. A decline in ProGRP levels was strongly correlated with response, whereby higher baseline levels were associated with subsequent higher relative declines of ProGRP during treatment. Using different cut-off levels for ProGRP decline during treatment (-50%, -70%, or -90%), we detected patients with no response to treatment based on ProGRP levels alone, with a sensitivity of 82.8%, 89.7% and 96.6%, and a specificity of 65.6%, 55.4%, and 39.8%, respectively. Specificity was increased by approximately 10% when only patients with baseline ProGRP levels exceeding 100 pg/ml were included.
To our knowledge, this is the largest SCLC cohort to date with available ProGRP data for therapy monitoring. The data showed that ProGRP levels at baseline were positively correlated with advanced disease stage, and decline in ProGRP levels during treatment was associated with tumor control in SCLC. The ProGRP assay used in this study is currently not cleared or approved for use in the USA.
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