Comprehensive Analysis of R-Spondin Fusions and RNF43 Mutations Implicate Novel Therapeutic Options in Colorectal Cancer

Andreas Seeber, Francesca Battaglin, Kai Zimmer, Florian Kocher, Yasmine Baca, Joanne Xiu, Gilbert Spizzo, Veronica Novotny-Diermayr, Dietmar Rieder, Alberto Puccini, Jeff Swensen, Michelle Ellis, Richard M. Goldberg, Axel Grothey, Anthony F. Shields, John L. Marshall, Benjamin A. Weinberg, Paul E. Sackstein, Kiat Hon Lim, Gek San TanChadi Nabhan, W. Michael Korn, Arno Amann, Zlatko Trajanoski, Martin D. Berger, Emil Lou, Dominik Wolf, Heinz Josef Lenz

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Purpose: Gene fusions involving R-spondin (RSPOfp) and RNF43 mutations have been shown to drive Wnt-dependent tumor initiation in colorectal cancer. Herein, we aimed to characterize the molecular features of RSPOfp/RNF43 mutated (mut) compared with wild-type (WT) colorectal cancers to gain insights into potential rationales for therapeutic strategies. Experimental Design: A discovery cohort was classified for RSPOfp/RNF43 status using DNA/RNA sequencing and IHC. An independent cohort was used to validate our findings. Results: The discovery cohort consisted of 7,245 colorectal cancer samples. RSPOfp and RNF43 mutations were detected in 1.3% (n ¼ 94) and 6.1% (n ¼ 443) of cases. We found 5 RSPO fusion events that had not previously been reported (e.g., IFNGR1–RSPO3). RNF43-mut tumors were associated with right-sided primary tumors. No RSPOfp tumors had RNF43 mutations. In comparison with WT colorectal cancers, RSPOfp tumors were characterized by a higher frequency of BRAF, BMPR1A, and SMAD4 mutations. APC mutations were observed in only a minority of RSPOfp-positive compared with WT cases (4.4% vs. 81.4%). Regarding RNF43 mutations, a higher rate of KMT2D and BRAF mutations were detectable compared with WT samples. Although RNF43 mutations were associated with a microsatellite instability (MSI-H)/mismatch repair deficiency (dMMR) phenotype (64.3%), and a tumor mutation burden ≥10 mt/Mb (65.8%), RSPOfp was not associated with MSI-H/ dMMR. The validation cohort replicated our genetic findings. Conclusions: This is the largest series of RSPOfp/RNF43-mut colorectal cancers reported to date. Comprehensive molecular analyses asserted the unique molecular landscape associated with RSPO/RNF43 and suggested potential alternative strategies to overcome the low clinical impact of Wnt-targeted agents and immunotherapy.

Original languageEnglish (US)
Pages (from-to)1863-1870
Number of pages8
JournalClinical Cancer Research
Issue number9
StatePublished - May 1 2022

Bibliographical note

Funding Information:
This work was supported by the National Cancer Institute (P30CA 014089).

Publisher Copyright:
©2022 The Authors; Published by the American Association for Cancer Research

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural


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