Laura Vroling

Sunitinib-Induced Myeloid Lineage Redistribution in Renal Cell Cancer Patients: CD1c+ Dendritic Cell Frequency Predicts Progression-Free Survival

Purpose: A disturbed myeloid lineage development with abnormally abundant neutrophils and impaired dendritic cell (DC) differentiation may contribute to tumor immune escape. We investigated the effect of sunitinib, a tyrosine kinase inhibitor of fms-like tyrosine kinase-3, KIT, and vascular endothelial growth factor receptors, on myeloid differentiation in renal cell cancer (RCC) patients. Experimental Design: Twenty-six advanced RCC patients were treated with sunitinib in a 4-week on/2-week off schedule. Enumeration and extensive phenotyping of myeloid subsets in the blood was done at baseline and at weeks 4 and 6 of the first treatment cycle. Baseline patient data were compared with sex- and age-matched healthy donor data. Results: Baseline frequencies of DC subsets were lower in RCC patients than in healthy donors. After 4 weeks of sunitinib treatment, a generalized decrease in myeloid frequencies was observed. Whereas neutrophils and monocytes, which were both abnormally high at baseline, remained low during the 2-week off period, DC rates recovered, resulting in a normalized myeloid lineage distribution. Subsequent to sunitinib treatment, an increase to high levels of myeloid DC (MDC) subset frequencies relative to other myeloid subsets, was specifically observed in patients experiencing tumor regression. Moreover, high CD1c/BDCA-1+ MDC frequencies were predictive for tumor regression and improved progression-free survival. Conclusion: The sunitinib-induced myeloid lineage redistribution observed in advanced RCC patients is consistent with an improved immune status. Immunologic recovery may contribute to clinical efficacy as suggested by the finding of highly increased MDC frequencies relative to other myeloid subsets in patients with tumor regression.

CD133 + circulating haematopoietic progenitor cells predict for response to sorafenib plus erlotinib in non-small cell lung cancer patients

Background:Blood-based biomarkers may be particularly useful for patient selection and prediction of treatment response for angiogenesis inhibitors. Circulating endothelial cells (CECs) and haematopoietic progenitor cells (HPCs) might have a role in tumour angiogenesis and in tumour growth. Measurement of CECs and HPCs in the blood of patients could be a simple, non-invasive way to monitor or predict responses to treatment.Methods:(VEGFR2+) CECs, (CD133+) HPCs, plasma vascular endothelial growth factor (VEGF) and erythropoietin were measured in blood from 25 non-small cell lung cancer (NSCLC) patients before and during treatment with sorafenib plus erlotinib (SO/ER). In order to assess the drug specificity of changes in CECs and HPCs, 18 patients treated with bevacizumab plus erlotinib (BV/ER) and 10 patients with erlotinib (ER) monotherapy were studied. Response was measured in all patient groups by Response Evaluation Criteria in Solid Tumors (RECIST).Results:At day 7, SO/ER-treated patients showed a three-fold increase in CECs (P<0.0001) comparable to BV/ER-treated patients (P<0.01), and the CECs did not change with erlotinib treatment (P=0.8). At day 7, CD133+/HPCs decreased with SO/ER treatment (P<0.0001). HPC numbers did not change with either BV/ER or erlotinib. In SO/ER-treated patients pre-treatment CD133+/HPCs were significantly lower in responders (P=0.01) and pre-treatment CD133+/HPC numbers lower than the median correlated with a longer time-to-progression (TTP) (P=0.037).Conclusion:Pre-treatment CD133+/HPCs are a promising candidate biomarker to further explore for use in selecting NSCLC patients who might benefit from SO/ER treatment.

VEGFR2 expressing circulating (progenitor) cell populations in volunteers and cancer patients

Circulating cells of several lineages are thought to participate in angiogenesis and tumor growth. Experimental studies in tumor-bearing mice have pointed to the potential importance of VEGF-responding circulating (endothelial) progenitor cells in tumor growth. We have studied circulating CD31- and/or CD34-positive cell populations with a low to moderate VEGFR2 expression in human volunteers and cancer patients. We recognized four cell populations, which were further characterized by their content of major hematopoietic progenitor, monocytic, endothelial and platelet markers. After establishing the test-retest stability of the measurements in nine patients, we determined the frequencies of the various cell populations in a group of 20 volunteers and 14 cancer patients. Two populations were markedly increased in cancer patients. Small CD45(neg)/CD34(bright)/VEGFR2+ cells amounted to 12 and 64 cells/ml (P < 0.0001), respectively, and 246/ml and 578/ml VEGFR2+/CD45(bright) (/CD14+) monocytic cells were present in controls and cancer patients, respectively (P = 0.017). A third population of CD45(dim)/CD34(bright)/VEGFR2(low) cells amounted to 25 and 30 cells/ml (P = 0.38). Unexpectedly, a population of mainly anucleated CD45(low)/CD31(bright)/CD41(bright) cells was present in numbers of 9,076 and 16,697/ml (P = 0.04) in volunteers and cancer patients, which contained a VEGFR2(low) (compared to IgG isotype control) expressing population amounting to 1,142 and 1,642 cells/ml (P = 0.12). This fourth population probably reflects large platelets. The role of the herein identified VEGFR2+ circulating cell populations deserve further investigation in cancer patients treated with VEGF(R)-targeted therapies. Quantification of such cell populations in the blood of tumor patients may be valuable to monitor the efficacy of anti-angiogenic treatment.

Sunitinib-induced hemoglobin changes are related to the dosing schedule.

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Sunitinib‐induced changes in circulating endothelial cell‐related proteins in patients with metastatic renal cell cancer

Vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors are effective agents in the treatment of metastatic renal cell cancer (mRCC). We here investigated whether inhibition of VEGFR signalin by sunitinib causes changes in plasma proteins associated with tumor endothelium. Forty‐three patients with mRCC received sunitinib 50 mg/day in a 4‐weeks on 2‐weeks off schedule. Sequential plasma samples were obtained before treatment (C1D1), on C1D14, on C1D28, and on C2D1 before start of cycle 2. Plasma levels were assessed for VEGF, soluble vascular cell adhesion molecule‐1 (sVCAM‐1), soluble intercellular cell adhesion molecule‐1 (sICAM‐1), von Willebrand factor (vWF), circulating angiopoietin‐2 (Ang‐2) and soluble Tie‐2 (sTie‐2). Total tumor burden was calculated at baseline and at first evaluation. Progression‐free survival (PFS) and overall survival (OS) were determined. Tumor burden was positively associated with baseline circulating Ang‐2 [Spearmans rho (ρ) = 0.378, p = 0.028] and vWF (ρ = 0.417, p = 0.008). During sunitinib treatment, circulating Ang‐2 and sTie‐2 significantly decreased (p < 0.001 for both), plasma levels of sVCAM‐1 and VEGF significantly increased (p = 0.022 and p < 0.001), whereas those of sICAM‐1 and vWF remained stable. These protein changes had recovered on C2D1. The reduction in circulating Ang‐2 levels on C1D28 was positively correlated with the percentage decrease in tumor burden (ρ = 0.605; p = 0.002). Baseline protein levels and subsequent changes were not associated with PFS or OS. In conclusion, sunitinib‐induced changes in Ang‐2, sTie‐2, sVCAM‐1 and VEGF are related to the administration schedule, while reduction in Ang‐2 is also associated with decrease in tumor burden.