Radiographic parameters in predicting outcome of patients with nonsquamous non-small cell lung cancer (NSCLC) treated with bevacizumab.

Abstract

e19009 Background: Bevacizumab has increased survival in NSCLC patients (pts) when added to standard chemotherapy. However, whether radiographic features at baseline and/or post-treatment can predict benefit from addition of anti-angiogenic therapy to standard chemotherapy remains unknown. In addition, the impact of VEGF-targeted therapy on CT parameters is not fully characterized. Methods: A retrospective review was performed using CT scans of pts enrolled into a prospective phase II clinical trial of pemetrexed, gemcitabine and bevacizumab in stage IV chemo-naïve, non-squamous, NSCLC pts (Wozniak A, et al. IASLC2011). Treatments were repeated every 2 wks (1 cycle). CT scans were obtained at baseline and at the end of every 4 cycles. The radiographic CT features of the primary tumors were retrospectively reviewed at baseline and after first 4 cycles. RECIST 1.1 and Morphology, Attenuation, Size, and Structure (MASS) criteria were used to assess tumor radiographic response. Results: Twenty-four pts (43% males; median age, 62 y [range: 41-82]), were evaluable for this analysis. On baseline CT, median tumor size was 2.9 cm (range: 1.6. to 6.3 cm), median attenuation was 56 HU (range: 31 to 87 HU), 81% of tumors had heterogeneous enhancement, and 50% of tumors demonstrated invasion of adjacent structures. Well-defined margins were noted in 43% of tumors and 81% had < 30% necrosis. On post-4 cycle CT, 63% of tumors had decreased long diameter (median 15% decrease), 81% had decreased attenuation (median 21% HU reduction) and 50% had increased necrosis. RECIST-defined PR was seen in 37%, SD in 56%; and PD in 1 (4%) based on size despite > 75% necrosis. MASS criteria response was favorable in 25% and non-favorable in 75% of tumors. Pts with tumors that demonstrated FR response by MASS after 4 cycles were more likely to have prolonged progression free survival (HR 2.94; p= 0.175). Conclusions: In tumors treated with anti-angiogenic therapy, imaging response criteria that include changes in tumor morphology, attenuation, and size may capture anti-tumor effect more accurately than size-based RECIST criteria alone. These results support the need for prospective investigation of the efficacy of MASS criteria.