Abstract 364P
Background
TRK inhibitors are a treatment option for patients with NTRK fusions positive tumors, including metastatic colorectal cancer (mCRC). However, the clinical behavior, including response to standard therapy and overall survival, in NTRK fusion positive mCRC is unknown which complicates the interpretation of tumor agnostic basket trials studying TRK inhibitors. We aim to estimate the prevalence of NTRK fusions in microsatellite instable (MSI) mCRC and to determine patient characteristics and clinical behavior of this NTRK fusion subtype.
Methods
FFPE tissue was requested from all MSI mCRC patients diagnosed between 2015 and 2020 in the Netherlands. Pan-Trk immunohistochemistry was used as screening method. Positive cases were analyzed by RNA-based NGS with Archer or FFPE-targeted locus capture to assess NTRK1, 2, and 3 rearrangements. Clinical data were retrieved from the Netherlands Cancer Registry.
Results
In total, 8 out of 203 tumors (3,9%) harbored an NTRK fusion: 7 rearrangements were found in the NTRK1 gene and 1 NTRK3-ETV6 fusion was detected. All NTRK-fusion positive tumors were RAS and BRAF wild-type. In the subgroup (n = 26) of RAS and BRAF wild-type MSI patients, prevalence of NTRK fusions was 23%. All NTRK-fusion positive tumors showed loss of MLH1 and PMS2 and MLH1 promotor hypermethylation was found in 7 out of 8 tumors. Benefit from chemotherapy (1/6) or anti-EGFR therapy (0/2) in NTRK-fusion positive patients was limited, but all four immunotherapy-treated patients had ongoing responses and a minimum overall survival of 470 days. The four patients who did not receive immunotherapy had a short overall survival (range 11-282 days).
Conclusions
In this population wide cohort study, NTRK fusions are most prevalent (23%) in RAS and BRAF wild-type MSI mCRC patients. This is the first study to suggest resistance to chemotherapy and anti-EGFR therapy in NTRK-fusion positive tumors leading to impaired overall survival. In contrast, immunotherapy seems to be effective in NTRK-fusion positive patients. The clinical condition of the patient probably dictates the choice of upfront immunotherapy versus TRK inhibitors in this subgroup. We recommend early testing for NTRK fusions in RAS and BRAF wild-type MSI patients.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Bayer.
Disclosure
S. Schraa: Financial Interests, Institutional, Research Grant: Personal Genome Diagnostics. M. Koopman: Financial Interests, Institutional, Advisory Board, advisory board and speaker: Pierre Fabre; Financial Interests, Institutional, Advisory Board: MSD, Bayer; Financial Interests, Institutional, Advisory Board, Advisory Board, speaker: Servier; Financial Interests, Institutional, Invited Speaker: Merck, BMS, Servier; Financial Interests, Institutional, Research Grant: Servier, Roche, Bayer, Bristol Myers Squibb, Merck, Personal Genomics Diagnostics, Sirtex, Pierre Fabre; Financial Interests, Institutional, Funding: Pierre Fabre, Amgen, Nordic Farma, Novartis, Merck, Servier, BMS; Non-Financial Interests, Leadership Role, vice-chair of DCCG: Dutch Colorectal Cancer Group; Non-Financial Interests, Advisory Role, Member of KWF scientific board: KWF; Non-Financial Interests, Other, ESMO faculty member for the Gastro-Intestinal Tumours – colorectal cancer: ESMO; Non-Financial Interests, Advisory Role, expert member of committee “regie op registers dure geneesmiddelen” ZINNL: ZiNNL; Non-Financial Interests, Advisory Role, CRC expert on Kanker.nl platform for answering online CRC questions of CRC (non) patients: Patient representative organisation (Kanker.nl); Non-Financial Interests, Leadership Role, chair of RWD & DH working group: ESMO; Other, Other, PI of the Dutch Prospective Colorectal Cancer Cohort study: PLCRC project. W. de Leng: Financial Interests, Institutional, Research Grant: Roche, BMS, Pfizer; Financial Interests, Institutional, Advisory Role: BMS, Janssen, Novartis. G. Vink: Financial Interests, Institutional, Research Grant: BMS, Merck, Servier, Personal Genome Diagnostics, Bayer, Sirtex, Pierre Fabre, Lilly. G.M. Bol: Financial Interests, Institutional, Advisory Role: Bayer, Terumo; Financial Interests, Institutional, Research Grant: Bayer. All other authors have declared no conflicts of interest.