Dynamic changes of phenotypically different circulating tumor cells sub-populations in patients with recurrent/refractory small cell lung cancer treated with pazopanib

Ippokratis Messaritakis,Fillipos Koinis,Eleftheria-Kleio Dermitzaki,Maria Plataki,Vassilis Georgoulias,Stella Apostolaki,Eleni Politaki,Dimitris Stoltidis,Athanasios Kotsakis

doi:10.1038/s41598-018-20502-1

Ippokratis Messaritakis, Fillipos Koinis + Show 7 more

Open Access

https://doi.org/10.1038/s41598-018-20502-1

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Abstract

The aim of the study was to investigate the effect of 2nd-line pazopanib on the different CTCs subpopulations in SCLC patients and evaluate the clinical relevance of their changes. Different CTCs subpopulations were evaluated before pazopanib initiation (n = 56 patients), after one-cycle (n = 35) and on disease progression (n = 45) by CellSearch and double immunofluorescence using anti-CKs and anti-Ki67, anti-M30 or anti-Vimentin antibodies. Before treatment, CTCs were detected in 50% of patients by CellSearch whereas 53.4%, 15.5% and 74.1% patients had CK+/Ki67+, CK+/M30+ and CK+/Vim+ CTCs, respectively. One pazopanib cycle significantly decreased the number of CTCs as detected by CellSearch (p = 0.043) as well as the number of CK+/Ki67+ (p < 0.001), CK+/M30+ (p = 0.015) and CK+/Vim+ (p < 0.001) cells. On disease progression, both the incidence and CTC numbers were significantly increased (CellSearch, p = 0.027; CK+/Ki67+, p < 0.001; CK+/M30+, p = 0.001 and CK+/Vim+, p < 0.001). In multivariate analysis, the detection of CK+/Vim+ CTCs after one treatment cycle (HR: 7.9, 95% CI: 2.9–21.8; p < 0.001) and CTCs number on disease progression, as assessed by CellSearch, (HR: 2.0, 95% CI: 1.0–6.0; p = 0.005) were emerged as independent factors associated with decreased OS. In conclusion, pazopanib can eliminate different CTC subpopulations in patients with relapsed SCLC. The analysis of CTCs could be used as a dynamic biomarker of treatment efficacy.

Highlights

SCLC accounts for about 13% of all lung cancer cases in the USA and at the time of presentation, about two thirds of the patients present extensive-stage disease[5]
The main outcomes of the clinical trial were: (a) pazopanib showed a promising activity as second-line treatment in patients with platinum-sensitive SCLC, and (b) circulating tumor cells (CTCs) monitoring and enumaration could contribute to the early detection of the patients who most likely will benefit from pazopanib and might serve as an early reliable surrogate biomarker that predict for response according to radiographic criteria
In multivariate analysis adjusting for these factors, lactate dehydrogenase (LDH), decreased sensitivity to platinum, increased number of CTCs on disease progression and detection of CK+/Vim+ CTCs after one treatment cycle emerged as independent prognostic factors associated with a decreased overall survival (OS) (HR: 4.7, p = 0.003; hazard ratios (HR): 2.0, p = 0.001; HR: 2.0, p = 0.005 and HR: 7.9, p < 0.001, respectively) (Table 4). To our knowledge this is the first study evaluating the dynamic role of different subpopulations of CTCs in patients with SCLC treated with an anti-angiogenic agent in the context of a phase II study which enrolled patients with recurrent and resistant/refractory disease

Summary

Introduction

SCLC accounts for about 13% of all lung cancer cases in the USA and at the time of presentation, about two thirds of the patients present extensive-stage disease[5]. It is interesting to note that both apoptotic (CK+/M30+) and proliferating (CK+/Ki67+) CTCs were never observed in circulating tumor microemboli (CTM) in contrast to bcl-2+ CTCs which could be detected in CTMs13 These data clearly suggest that the different subpopulations of CTCs in patients with SCLC may have a differential biologic behavior which could characterize the aggressive potential of the disease and its resistance to treatment[20,21]. It has been shown that CTCs from patients with early and metastatic breast cancer express VEGF and VEGFR222, suggesting the existence of an autocrine mechanism which could be involved in the metastatic process Based on these data, a correlative translational research study was undertaken in order to investigate the effect of 2nd line pazopanib on the different subpopulations of CTCs in patients with SCLC and, more especially, to evaluate the proliferative, apoptotic and EMT status of these cells

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