Introduction. The assessment of PD-L1 expression by immunohistochemistry is mandatoryfor the administration as first-line therapy of the anti PD-1 check-point inhibitor Pembrolizumab in patients with advanced non-small-cell lung cancer (NSCLC). Currently, only formalin-fixed paraffin-embedded samples are acceptable for PD-L1 immunostaining with the anti-PD-L1 antibodies 22-C3 and SP263. We investigated retrospectively the accuracy of the anti PD-L1 antibodies 22-C3, 28-28, SP263 in 50 paired histological samples and cytological smears of NSCLC patients. Results. The accuracy of the three antibodies for the detection of PD-L1 in histological samples was higher for the antibody SP263 (AUC/ROC =1) compared to the clones 28-8 (AUC/ROC =,991) and 22-C3 (AUC/ROC =,942). The overall concordance between histological samples and cytological smears using the SP263 clone was moderate (kappa =0,364). However when the cyto-histological concordance was calculated using just the <50% vs ≥50% cut-off the agreement (kappa =0.626) was good. The accuracy of the antibody SP263 in cytological smears was good (AUC/ROC =,921). A fluorescent in situ hybridization analysis on 10 histological cases positive for PD-L1 at immunohistochemistry showed amplification of the CD274 gene only in one case. Conclusions. Immunocytochemical staining for PD-L1 in diagnostic cytological smears of NSCLC is feasible and applicable at least using the >50% cancer cell cut-off. The three antibodies SP263, 22-C3 and 28-8 are all suitable for the diagnostic detection of PD-L1 on tissue sections with a superiority of the SP263 clone. The implementation of PD-L1 immunocytochemistry on cytological smears will likely expand the pool of NSCLC patients candidate to first-line immunotherapy.

The organic anion transporter peptides (OATP) 1B1 and 1B3 are hepatocytic-specific transporters determinant for the uptake of the contrast media Gd-EOB-DTPA during magnetic resonance, but variably lost in hepatocellular carcinoma (HCC). Here, we studied a series of HCCs from livers that underwent liver transplantation (OLT) and correlated the expression of OATP 1B1/1B3 with HCC morphological features and the expression of the biliary-type keratins K7 and K19, the latter previously correlated with a worse prognosis after OLT. Seventy-five HCCs from 69 OLT patients were evaluated by histology and immunohistochemistry with monoclonal antibodies against OATP 1B1/1B3, K7, and K19. Histopathological and immunohistochemical features were therefore compared to recipient follow-up data. Thirty-four (45%) HCCs were completely OATP-, and 18 (24%) showed positivity for K7 and/or K19. We observed a significant inverse correlation between OATP and K7/19 expression (P < 0.001): all OATP+ cases were K7/19-, while all K7+ and/or K19+ cases were OATP-. Sixteen cases were negative for all antibodies. No correlation was found between histopathological features and immunohistochemistry. Twenty-five recipients experienced HCC recurrence, and ten died from neoplastic recurrence. Neither OATP nor keratin expressions were correlated with HCC recurrence, while OATP negativity significantly correlated with HCC-related death after recurrence (P = 0.036). In conclusion, HCCs show a progressive loss in OATP immunoreactivity that correlates with the gain of a biliary phenotype. Although further studies are required to define these findings better, our results support the idea that OATP could be used together with K7/19 to identify a phenotypical "spectrum" in HCC progression.

Detection of KRAS mutations in archival pathology samples is critical for therapeutic appropriateness of anti-EGFR monoclonal antibodies in colorectal cancer. We compared the sensitivity, specificity, and accuracy of Sanger sequencing, ARMS-Scorpion (TheraScreen®) real-time polymerase chain reaction (PCR), pyrosequencing, chip array hybridization, and 454 next-generation sequencing to assess KRAS codon 12 and 13 mutations in 60 nonconsecutive selected cases of colorectal cancer. Twenty of the 60 cases were detected as wild-type KRAS by all methods with 100% specificity. Among the 40 mutated cases, 13 were discrepant with at least one method. The sensitivity was 85%, 90%, 93%, and 92%, and the accuracy was 90%, 93%, 95%, and 95% for Sanger sequencing, TheraScreen real-time PCR, pyrosequencing, and chip array hybridization, respectively. The main limitation of Sanger sequencing was its low analytical sensitivity, whereas TheraScreen real-time PCR, pyrosequencing, and chip array hybridization showed higher sensitivity but suffered from the limitations of predesigned assays. Concordance between the methods was k = 0.79 for Sanger sequencing and k > 0.85 for the other techniques. Tumor cell enrichment correlated significantly with the abundance of KRAS-mutated deoxyribonucleic acid (DNA), evaluated as ΔCt for TheraScreen real-time PCR (P = 0.03), percentage of mutation for pyrosequencing (P = 0.001), ratio for chip array hybridization (P = 0.003), and percentage of mutation for 454 next-generation sequencing (P = 0.004). Also, 454 next-generation sequencing showed the best cross correlation for quantification of mutation abundance compared with all the other methods (P < 0.001). Our comparison showed the superiority of next-generation sequencing over the other techniques in terms of sensitivity and specificity. Next-generation sequencing will replace Sanger sequencing as the reference technique for diagnostic detection of KRAS mutation in archival tumor tissues.

No abstract