MEK plus PI3K/mTORC1/2 Therapeutic Efficacy Is Impacted by TP53 Mutation in Preclinical Models of Colorectal Cancer

Celina García-García, Martín A. Rivas, Yasir H. Ibrahim, María Teresa Calvo, Albert Gris-Oliver, Olga Rodríguez, Judit Grueso, Pilar Antón, Marta Guzmán, Claudia Aura, Paolo Nuciforo, Katti Jessen, Guillem Argilés, Rodrigo Dienstmann, Andrea Bertotti, Livio Trusolino, Judit Matito, Ana Vivancos, Irene Chicote, Héctor G. PalmerJosep Tabernero, Maurizio Scaltriti, José Baselga, Violeta Serra

Research output: Contribution to journalArticlepeer-review


Purpose: PI3K pathway activation occurs in concomitance with RAS/BRAF mutations in colorectal cancer, limiting the sensitivity to targeted therapies. Several clinical studies are being conducted to test the tolerability and clinical activity of dual MEK and PI3K pathway blockade in solid tumors. Experimental Design: In the present study, we explored the efficacy of dual pathway blockade in colorectal cancer preclinical models harboring concomitant activation of the ERK and PI3K pathways. Moreover, we investigated if TP53 mutation affects the response to this therapy. Results: Dual MEK and mTORC1/2 blockade resulted in synergistic antiproliferative effects in cell lines bearing alterations in KRAS/BRAF and PIK3CA/PTEN. Although the on-treatment cellcycle effects were not affected by the TP53 status, a marked proapoptotic response to therapy was observed exclusively in wild-type TP53 colorectal cancer models. We further interrogated two independent panels of KRAS/BRAF- and PIK3CA/PTENaltered cell line- and patient-derived tumor xenografts for the antitumor response toward this combination of agents. A combination response that resulted in substantial antitumor activity was exclusively observed among the wild-type TP53 models (two out of five, 40%), but there was no such response across the eight mutant TP53 models (0%). Interestingly, within a cohort of 14 patients with colorectal cancer treated with these agents for their metastatic disease, two patients with long-lasting responses (32 weeks) had TP53 wild-type tumors. Conclusions: Our data support that, in wild-type TP53 colorectal cancer cells with ERK and PI3K pathway alterations, MEK blockade results in potent p21 induction, preventing apoptosis to occur. In turn, mTORC1/2 inhibition blocks MEK inhibitor- mediated p21 induction, unleashing apoptosis.

Original languageEnglish
Pages (from-to)5499-5510
Number of pages12
JournalClinical Cancer Research
Issue number24
Publication statusPublished - Dec 15 2015

ASJC Scopus subject areas

  • Cancer Research
  • Oncology


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