EGFR activity addiction facilitates anti-ERBB based combination treatment of squamous bladder cancer

Michael Rose,Thorsten Ecke,Nadine Rüchel,Marieta Toma,Ruth Knuechel,Elke Eltze,Julia Wirtz,Marie Eyll,Tobias Grimm,Tanja Waldmann,Andreas Bleilevens,Maximilian Wenz,David Horst,Melanie Gereitzig,Stefan Denzinger,Angela Maurer,Bernd Denecke,Edwin Herrmann,Mirja Geelvink,Jochen Maurer,Thomas-Alexander Vögeli ,Nadine T Gaisa

doi:10.1038/s41388-020-01465-y

Abstract

Recent findings suggested a benefit of anti-EGFR therapy for basal-like muscle-invasive bladder cancer (MIBC). However, the impact on bladder cancer with substantial squamous differentiation (Sq-BLCA) and especially pure squamous cell carcinoma (SCC) remains unknown. Therefore, we comprehensively characterized pure and mixed Sq-BLCA (n = 125) on genetic and protein expression level, and performed functional pathway and drug-response analyses with cell line models and isolated primary SCC (p-SCC) cells of the human urinary bladder. We identified abundant EGFR expression in 95% of Sq-BLCA without evidence for activating EGFR mutations. Both SCaBER and p-SCC cells were sensitive to EGFR tyrosine kinase inhibitors (TKIs: erlotinib and gefitinib). Combined treatment with anti-EGFR TKIs and varying chemotherapeutics led to a concentration-dependent synergism in SCC cells according to the Chou-Talalay method. In addition, the siRNA knockdown of EGFR impaired SCaBER viability suggesting a putative “Achilles heel” of Sq-BLCA. The observed effects seem Sq-BLCA-specific since non-basal urothelial cancer cells were characterized by poor TKI sensitivity associated with a short-term feedback response potentially attenuating anti-tumor activity. Hence, our findings give further insights into a crucial, Sq-BLCA-specific role of the ERBB signaling pathway proposing improved effectiveness of anti-EGFR based regimens in combination with chemotherapeutics in squamous bladder cancers with wild-type EGFR-overexpression.

Highlights

Bladder cancer is the 9th common cancer worldwide [1] comprising a wide spectrum of tumors including cancers with squamous differentiation (Sq-BLCA), i.e., urothelial cancers with substantial squamous-differentiationRegensburg, Germany Department of Urology, Helios Hospital Bad Saarow, Bad Saarow, Germany Department of Urology, RWTH Aachen University, Aachen, Germany Present address: Institute of Pathology, University Hospital Bonn, Bonn, Germany (MIX-SCC) and pure squamous cell carcinoma (SCC) [2]
EGFR inhibition by monoclonal antibodies or small molecule tyrosine kinase inhibitors (TKIs) has been approved for the treatment of tumor entities like RAS wild-type colorectal cancers [28], HNSCC [29], and EGFR-mutated NSCLC [16, 30]
We provide a rationale for combining EGFR inhibitors with standard chemotherapy as treatment strategy for pure and mixed squamous bladder cancers, characterized by a strong dependency on wild-type EGFR signaling

Summary

Introduction

Bladder cancer is the 9th common cancer worldwide [1] comprising a wide spectrum of tumors including cancers with squamous differentiation (Sq-BLCA), i.e., urothelial cancers with substantial squamous-differentiation. Sq-BLCA shows shorter overall survival compared with pure urothelial cancer [3]. Accumulating evidence suggests poor response of muscle-invasive bladder cancer (MIBC) with squamous features to standard chemotherapy (MVAC—methotrexate, vinblastine, doxorubicin, and cisplatin or GC—gemcitabine and cisplatin) [4]. Basal tumors with squamous features may benefit from (neoadjuvant) chemotherapeutic regimens [8]. In 2014, Rebouissou and colleagues suggested the basal-like bladder cancer subgroup to be sensitive for anti-EGFR treatment. Increased activation of the EGFR signaling pathway was shown to correlate with enhanced antiEGFR drug sensitivity in vitro and in vivo [9]

Methods

Results

Conclusion