Defining the boundaries and expanding the utility of head and neck cancer patient derived xenografts

Abstract

Background Patient derived xenografts (PDXs) represent an essential tool in oncologic research, and we sought to further expand our repertoire of head and neck squamous cell carcinoma (HNSCC) while determining potential boundaries for this system. Methods We consented new patients for PDX development and determined if a 24-hour time delay from tumor excision to xenograft implantation affected PDX establishment. We developed a tissue microarray (TMA) from formalin fixed, paraffin embedded PDXs and their subsequent passages and carried out quantitative immunohistochemistry for EGFR, pEGFR, pAkt, pERK and ERCC1. First and last passaged PDXs were compared via a paired t-test to examine for the stability of protein expression across passages. We performed a similar comparison of the mutational profile of the patient tumor and resulting xenografts using a targeted sequencing approach. Results No patient/tumor characteristics influenced PDX take rate and the 24-hour time delay from tumor excision to xenograft implantation did not affect PDX establishment, growth or histology. There was no significant difference in biomarker expression between the first and last passaged PDXs for EGFR, pEGFR, pAkt, and ERCC1. For pERK there was a significant difference (p=0.002), but further analysis demonstrated this only arose in three of 15 PDXs. Targeted sequencing revealed striking stability of passenger and likely driver mutations from patient to xenograft. Conclusions The stability of protein expression across PDX passages will hopefully allow greater investigation of predictive biomarkers in order to identify ones for further pre-clinical and clinical investigation.

Cotargeting mTORC and EGFR Signaling as a Therapeutic Strategy in HNSCC

“…We have previously described the establishment and other characteristics of our cohort of PDX models(31–33); here we show hotspot mutational profiling using an Illumina cancer targeted sequencing panel, with key genes and patient demographic data highlighted in Figure 1A. We identified two PDXs in our cohort containing PIK3CA helical-domain activating mutations, as well as a range of PTEN expression levels as analyzed by IHC (Figure 1A and S1).…”

“…Total genomic DNA was isolated from PDX FFPE tissue and HNSCC cell lines and sequenced using the Illumina TruSeq Cancer Amplicon panel and analyzed as described previously(31). Sequencing data has been deposited with the sequence read archive under BioProject ID: PRJNA381909.…”

Radiosensitization of Adenoid Cystic Carcinoma with MDM2 Inhibition

“…As part of the standard characterization of our PDXs, tumor tissue was isolated, gDNA was prepared, and Illumina HotSpot sequencing was performed as previously described (38) to determine the TP53 status of this tumor. With over 50× coverage over the most common sites of TP53 mutation, no oncogenic TP53 SNPs or INDELs were observed in either the patient tumor or any subsequent passage (Figure 1B).…”

“…Additional slides were processed by the UW Translational Research in Pathology lab to assess for expression of p63, CD117, and CK5/6 by immunohistochemistry (IHC). Staining for expression of p53, p-p53, and Ki-67 was performed by standard IHC techniques as described previously(12,38). See Table S1 for reagent details.…”

Anti‐oral cancer effects of triptolide by downregulation of DcR3 in vitro, in vivo, and in preclinical patient‐derived tumor xenograft model

“…Appropriate preclinical models could advance cancer drug research. A patient‐derived tumor xenograft (PDTX) model has numerous advantages over standard xenograft models in preclinical trials of novel anticancer drugs because PDTXs are more capable of retaining the genetic, molecular, and histological heterogeneity of patient tumors through serial passage in a mouse model …”