A subset of esophageal squamous cell carcinoma patient-derived xenografts respond to cetuximab, which is predicted by high EGFR expression and amplification.

BACKGROUND: Epidermal growth factor receptor (EGFR) is reportedly overexpressed in most esophageal tumors, but most targeted therapies showed no efficacy in non-selected patients. This study aims at investigating the adaptive cetuximab subset in a cohort of esophageal squamous cell carcinoma (ESCC) patient-derived xenografts (PDXs). METHODS: A large panel of ESCC PDXs has been established. The copy number, mRNA expression and immunohistochemistry (IHC) of key EGFR pathways have been examined along with cetuximab response. A preclinical trial on a randomly selected cohort of 16 ESCC PDXs was conducted, and the genomic annotations of these models were compared against the efficacy readout of the mouse trial. RESULTS: The trial identified that 7 of 16 (43.8%) responded to cetuximab (ΔT/ΔC <0 as responders). The gene amplification and expression analysis indicated that EGFR copy number ≥5 (P=0.035), high EGFR mRNA expression (P=0.001) and IHC score of 2-3 (P=0.034) are associated with tumor growth inhibition by cetuximab, suggesting EGFR may function as a single predictive biomarker for cetuximab response in ESCC. CONCLUSIONS: Overall, our results suggest that an ESCC subtype with EGFR amplification and overexpression benefits from cetuximab treatment, which warrants further clinical confirmation.

A subset of gastric cancers with EGFR amplification and overexpression respond to cetuximab therapy.

A preclinical trial identified 4 of 20 (20%) gastric cancer (GC) patient-derived xenografts responded to cetuximab. Genome-wide profiling and additional investigations revealed that high EGFR mRNA expression and immunohistochemistry score (3+) are associated with tumor growth inhibition. Furthermore, EGFR amplification were observed in 2/4 (50%) responders with average copy number 5.8 and >15 respectively. Our data suggest that a GC subtype with EGFR amplification and overexpression benefit from cetuximab treatment.

Overcoming erlotinib resistance with tailored treatment regimen in patient-derived xenografts from naïve Asian NSCLC patients.

Overall benefits of EGFR-TKIs are limited because these treatments are largely only for adenocarcinoma (ADC) with EGFR activating mutation. The treatments also usually lead to development of resistances. We have established a panel of patient-derived xenografts (PDXs) from treatment naïve Asian NSCLC patients, including those containing "classic" EGFR activating mutations. Some of these EGFR-mutated PDXs do not respond to erlotinib: LU1868 containing L858R/T790M mutations, and LU0858 having L858R mutation as well as c-MET gene amplification, both squamous cell carcinoma (SCC). Treatment of LU0858 with crizotinib, a small molecule inhibitor for ALK and c-MET, inhibited tumor growth and c-MET activity. Combination of erlotinib and crizotinib caused complete response, indicating the activation of both EGFR and c-MET promote its growth/survival. LU2503 and LU1901, both with wild-type EGFR and c-MET gene amplification, showed complete response to crizotinib alone, suggesting that c-MET gene amplification, not EGFR signaling, is the main oncogenic driver. Interestingly, LU1868 with the EGFR L858R/T790M, but without c-met amplification, had a complete response to cetuximab. Our data offer novel practical approaches to overcome the two most common resistances to EGFR-TKIs seen in the clinic using marketed target therapies.

Radiographic findings of Wistar rats fed with T-2 toxin and Kashin-Beck disease-affected diet.

OBJECTIVE: To characterize the features of radiographic abnormalities of the tibial bone in Wistar rats which have been fed T-2 toxin and Kashin-Beck disease (KBD) epidemic district food. METHODS: Ninety Wistar rats were divided into five groups. Group A was fed with a normal diet as control; group B was fed with a normal diet and T-2 toxin; group C was fed with a low-nutrition diet and T-2 toxin; group D was fed with a low-nutrition diet; and group E was fed with a KBD-affected diet. At 4, 8 and 12 weeks, six rats from each group were radiographed. After radiographic examination, samples of left knees were harvested and stained with hematoxylin and eosin. RESULTS: At 8 and 12 weeks, there were radiological changes in the epiphyseal plate. Abnormal radiological signs of blurring, thinning and irregularity were seen in groups C and E rats, and the length of tibial bones showed significant difference in the KBD-fed rats and low-nutrition diet combined T-2 toxin rats, compared to the control group rats (P < 0.05). The epiphyseal plates showed more obvious necrosis of chondrocytes in groups C and E. CONCLUSIONS: A rat model of KBD can be established by a KBD-affected diet; proximal epiphyseal plate and metaphyseal bone of the tibia abnormalities on radiographs and histopathology were present in KBD model rats. A low nutrition diet may be involved the aetiology of KBD, and determination of this should be studied in the future.