Definition of a fluorescence in-situ hybridization score identifies high- and low-level FGFR1 amplification types in squamous cell lung cancer.
We recently reported fibroblast growth factor receptor-type 1 (FGFR1) amplification to be associated with therapeutically tractable FGFR1 dependency in squamous cell lung cancer. This makes FGFR1 a novel target for directed therapy in these tumors. To reproducibly identify patients for clinical studies, we developed a standardized reading and evaluation strategy for FGFR1 fluorescence in-situ hybridization (FISH) and propose evaluation criteria, describe different patterns of low- and high-level amplifications and report on the prevalence of FGFR1 amplifications in pulmonary carcinomas. A total of 420 lung cancer patients including 307 squamous carcinomas, 100 adenocarcinomas of the lung and 13 carcinomas of other types were analyzed for FGFR1 amplification using a dual color FISH. We found heterogeneous and different patterns of gene copy numbers. FGFR1 amplifications were observed in 20% of pulmonary squamous carcinomas but not in adenocarcinomas. High-level amplification (as defined by an FGFR1/centromer 8 (CEN8) ratio ≥2.0, or average number of FGFR1 signals per tumor cell nucleus ≥6, or the percentage of tumor cells containing ≥15 FGFR1 signals or large clusters ≥10%) was detected at a frequency of 16% and low-level amplification (as defined by ≥5 FGFR1 signals in ≥50% of tumor cells) at a frequency of 4%. We conclude that FGFR1 amplification is one of the most frequent therapeutically tractable genetic lesions in pulmonary carcinomas. Standardized reporting of FGFR1 amplification in squamous carcinomas of the lung will become increasingly important to correlate therapeutic responses with FGFR1 inhibitors in clinical studies. Thus, our reading and evaluation strategy might serve as a basis for identifying patients for ongoing and upcoming clinical trials.
Centre of Integrated Oncology Köln-Bonn, Institute of Pathology, University Hospital Cologne, Cologne, Germany.
Hans-Ulrich
HU
Schildhaus
Lukas C
LC
Heukamp
Sabine
S
Merkelbach-Bruse
Katharina
K
Riesner
Katja
K
Schmitz
Elke
E
Binot
Ellen
E
Paggen
Kerstin
K
Albus
Wolfgang
W
Schulte
Yon-Dschun
YD
Ko
Andreas
A
Schlesinger
Sascha
S
Ansén
Walburga
W
Engel-Riedel
Michael
M
Brockmann
Monika
M
Serke
Ulrich
U
Gerigk
Sebastian
S
Huss
Friederike
F
Göke
Sven
S
Perner
Khosro
K
Hekmat
Konrad F
KF
Frank
Marcel
M
Reiser
Roland
R
Schnell
Marc
M
Bos
Christian
C
Mattonet
Martin
M
Sos
Erich
E
Stoelben
Jürgen
J
Wolf
Thomas
T
Zander
Reinhard
R
Buettner
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D005404:Fixatives; D005557:Formaldehyde; D005784:Gene Amplification; D018628:Gene Dosage; D020022:Genetic Predisposition to Disease; D005858:Germany; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D016612:Paraffin Embedding; D010641:Phenotype; D011237:Predictive Value of Tests; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000235:genetics*; D015203:Reproducibility of Results; D016707:Tissue Fixation
D005404:Fixatives; D005557:Formaldehyde; C496348:FGFR1 protein, human; D051496:Receptor, Fibroblast Growth Factor, Type 1