br ECOG PS European Cooperative Oncology Group performance
ECOG PS = European Cooperative Oncology Group performance status; Hb = haemoglobin; IQR = interquartile range; LDH = lactate dehydrogenase; N = number;
NR = no result; PB = peripheral blood; PSA = prostate-specific antigen.
b Kruskal-Wallis equality-of-populations rank test.
3.4. CTC AR-V7 positivity is associated with higher CellSearch CTC enumeration
Having demonstrated that CTC+/AR-V7+ patients have more advanced disease, we next investigated the association between CTC AR-V7 status and contemporaneous Cell-Search CTC enumeration in 202 samples from 136 mCRPC patients (CTC cohort; Fig. 2A and Supplementary Fig. 1). The median (interquartile range [IQR]) number of days between contemporaneous samples was (0.0–0.0); 174 samples were taken on the same day and 28 samples within 1 month. The CellSearch CTC count (median; IQR) was significantly lower (p < 0.001) in CTC (4; 0–23) compared with CTC+ (26; 5–99) samples by AdnaTest (Fig. 2B and Supplementary Fig. 5). Furthermore, samples that were CTC +/AR-V7 had significantly lower (p < 0.001) CTC counts (9; 2–64) than those that were CTC+/AR-V7+ (60; 19–184; Fig. 2C). Finally, there was a statistically significant
Please cite this article in press as: Sharp A, et al. Clinical Utility of Circulating Tumour Cell Androgen MK0683 Splice Variant-7 Status in Metastatic Castration-resistant Prostate Cancer. Eur Urol (2019), https://doi.org/10.1016/j.eururo.2019.04.006
Fig. 2 – CTC AR-V7 positivity is associated with CellSearch CTC enumeration in mCRPC. (A) A total of 202 peripheral blood (PB) draws from 136 mCRPC patients for AdnaTest analysis with contemporaneous (all within a month) PB draws for CellSearch CTC enumeration. (B) CellSearch enumeration for contemporaneous samples with (grey boxes) and without (white boxes) CTCs detected by AdnaTest are shown. Median CTCs/7.5 ml PB and interquartile range are shown. The p value was calculated using Mann-Whitney test. (C) For 136 AdnaTest CTC-positive samples (B, grey boxes), CellSearch counts for contemporaneous AR-V7 positive (red boxes) and AR-V7 negative (grey boxes) samples detected by AdnaTest are shown. Median (and interquartile range) CTCs/7.5 ml in PB are shown. The p value was calculated using the Mann-Whitney test. (D) For 71 AdnaTest CTC AR-V7 positive samples (C, red boxes), CellSearch enumeration is compared with continuous (mean of technical replicates) AR-V7 mRNA expression (copies/ml). Spearman's rank correlation is shown. * One sample had no CTC by CellSearch enumeration and was not plotted. AR-V7 = androgen receptor splice variant-7; CTC = circulating tumour cell; mCRPC = metastatic castration-resistant prostate cancer.
correlation between mean CTC AR-V7 mRNA expression (copies/ml) and CellSearch CTC count in CTC+/AR-V7+ patients (r = 0.52 [95% confidence interval CI 0.32– 0.68]; p < 0.001; Fig. 2D). These data demonstrate the limitation of CTC detection by AdnaTest. Furthermore, AdnaTest CTC+/AR-V7+ status is associated with higher CellSearch CTC counts.
3.5. Differences are observed between CTC AR-V7 status and matched tumour biopsy AR-V7 protein expression in patients with mCRPC
Next, we determined AR-V7 status in 65 contemporaneous, same-patient PB samples and metastatic biopsies from 58 mCRPC patients (IHC cohort; Fig. 3A and Supplementary Fig. 1) to determine whether the CTC AR-V7 AdnaTest gave a precise estimate of tumour AR-V7 protein expression. The
median (IQR) number of days between contemporaneous samples was 5 (0–9). H-scores (HSs) were determined by IHC for nuclear AR-V7 and AR-FL (Supplementary Fig. 6). Nuclear AR-V7, but not AR-FL, protein expression (median HS; IQR) was significantly (p = 0.004) higher for CTC+/AR-V7
16) AdnaTest CTC patients had detectable AR-V7 protein expression in their matched mCRPC biopsy (Fig. 3B and 3D). All mCRPC biopsies were positive for AR-FL protein expression and all CTC+ samples expressed AR-FL mRNA (Fig. 3C and 3D). Finally, for mCRPC biopsies with next-generation sequencing available, AR amplification was more common in CTC+/AR-V7+ (19/26; 73%) patients compared