Therapeutic potential of combined BRAF/MEK blockade in BRAF-wild type preclinical tumor models

Anais Del Curatolo, Fabiana Conciatori, Ursula Cesta Incani, Chiara Bazzichetto, Italia Falcone, Vincenzo Corbo, Sabrina D'Agosto, Adriana Eramo, Giovanni Sette, Isabella Sperduti, Teresa De Luca, Mirko Marabese, Senji Shirasawa, Ruggero De Maria, Aldo Scarpa, Massimo Broggini, Donatella Del Bufalo, Francesco Cognetti, Michele Milella, Ludovica Ciuffreda

Research output: Contribution to journalArticle

Abstract

Background: Mounting evidence suggests that RAF-mediated MEK activation plays a crucial role in paradox MAPK (re)activation, leading to resistance and therapeutic failure with agents hitting a single step along the MAPK cascade. Methods: We examined the molecular and functional effects of single and combined BRAF (dabrafenib), pan-RAF (RAF265), MEK (trametinib) and EGFR/HER2 (lapatinib) inhibition, using Western Blot and conservative isobologram analysis to assess functional synergism, and explored genetic determinants of synergistic interactions. Immunoprecipitation based assays were used to detect the interaction between BRAF and CRAF. The Mann-Whitney U test was used for comparing quantitative variables. Results: Here we demonstrated that a combination of MEK and BRAF inhibitors overcomes paradoxical MAPK activation (induced by BRAF inhibitors) in BRAF-wt/RAS-mut NSCLC and PDAC in vitro. This results in growth inhibitory synergism, both in vitro and in vivo, in the majority (65%) of the cellular models analyzed, encompassing cell lines and patient-derived cancer stem cells and organoids. However, RAS mutational status is not the sole determinant of functional synergism between RAF and MEK inhibitors, as demonstrated in KRAS isogenic tumor cell line models. Moreover, in EGFR-driven contexts, paradoxical MAPK (re)activation in response to selective BRAF inhibition was dependent on EGFR family signaling and could be offset by simultaneous EGFR/HER-2 blockade. Conclusions: Overall, our data indicate that RAF inhibition-induced paradoxical MAPK activation could be exploited for therapeutic purposes by simultaneously targeting both RAF and MEK (and potentially EGFR family members) in appropriate molecular contexts. KRAS mutation per se does not effectively predict therapeutic synergism and other biomarkers need to be developed to identify patients potentially deriving benefit from combined BRAF/MEK targeting.

Original languageEnglish
Article number140
JournalJournal of Experimental and Clinical Cancer Research
Volume37
Issue number1
DOIs
Publication statusPublished - Jul 9 2018

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Mitogen-Activated Protein Kinase Kinases
Neoplasms
Therapeutics
Organoids
Neoplastic Stem Cells
Nonparametric Statistics
Tumor Cell Line
Immunoprecipitation
Biomarkers
Western Blotting
Cell Line
Mutation
Growth
Inhibition (Psychology)

Keywords

  • BRAF
  • Combination therapy
  • MAPK
  • MEK
  • Paradoxical effect

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Del Curatolo, A., Conciatori, F., Cesta Incani, U., Bazzichetto, C., Falcone, I., Corbo, V., ... Ciuffreda, L. (2018). Therapeutic potential of combined BRAF/MEK blockade in BRAF-wild type preclinical tumor models. Journal of Experimental and Clinical Cancer Research, 37(1), [140]. https://doi.org/10.1186/s13046-018-0820-5

Therapeutic potential of combined BRAF/MEK blockade in BRAF-wild type preclinical tumor models. / Del Curatolo, Anais; Conciatori, Fabiana; Cesta Incani, Ursula; Bazzichetto, Chiara; Falcone, Italia; Corbo, Vincenzo; D'Agosto, Sabrina; Eramo, Adriana; Sette, Giovanni; Sperduti, Isabella; De Luca, Teresa; Marabese, Mirko; Shirasawa, Senji; De Maria, Ruggero; Scarpa, Aldo; Broggini, Massimo; Del Bufalo, Donatella; Cognetti, Francesco; Milella, Michele; Ciuffreda, Ludovica.

In: Journal of Experimental and Clinical Cancer Research, Vol. 37, No. 1, 140, 09.07.2018.

Research output: Contribution to journalArticle

Del Curatolo, A, Conciatori, F, Cesta Incani, U, Bazzichetto, C, Falcone, I, Corbo, V, D'Agosto, S, Eramo, A, Sette, G, Sperduti, I, De Luca, T, Marabese, M, Shirasawa, S, De Maria, R, Scarpa, A, Broggini, M, Del Bufalo, D, Cognetti, F, Milella, M & Ciuffreda, L 2018, 'Therapeutic potential of combined BRAF/MEK blockade in BRAF-wild type preclinical tumor models', Journal of Experimental and Clinical Cancer Research, vol. 37, no. 1, 140. https://doi.org/10.1186/s13046-018-0820-5
Del Curatolo, Anais ; Conciatori, Fabiana ; Cesta Incani, Ursula ; Bazzichetto, Chiara ; Falcone, Italia ; Corbo, Vincenzo ; D'Agosto, Sabrina ; Eramo, Adriana ; Sette, Giovanni ; Sperduti, Isabella ; De Luca, Teresa ; Marabese, Mirko ; Shirasawa, Senji ; De Maria, Ruggero ; Scarpa, Aldo ; Broggini, Massimo ; Del Bufalo, Donatella ; Cognetti, Francesco ; Milella, Michele ; Ciuffreda, Ludovica. / Therapeutic potential of combined BRAF/MEK blockade in BRAF-wild type preclinical tumor models. In: Journal of Experimental and Clinical Cancer Research. 2018 ; Vol. 37, No. 1.
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T1 - Therapeutic potential of combined BRAF/MEK blockade in BRAF-wild type preclinical tumor models

AU - Del Curatolo, Anais

AU - Conciatori, Fabiana

AU - Cesta Incani, Ursula

AU - Bazzichetto, Chiara

AU - Falcone, Italia

AU - Corbo, Vincenzo

AU - D'Agosto, Sabrina

AU - Eramo, Adriana

AU - Sette, Giovanni

AU - Sperduti, Isabella

AU - De Luca, Teresa

AU - Marabese, Mirko

AU - Shirasawa, Senji

AU - De Maria, Ruggero

AU - Scarpa, Aldo

AU - Broggini, Massimo

AU - Del Bufalo, Donatella

AU - Cognetti, Francesco

AU - Milella, Michele

AU - Ciuffreda, Ludovica

PY - 2018/7/9

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N2 - Background: Mounting evidence suggests that RAF-mediated MEK activation plays a crucial role in paradox MAPK (re)activation, leading to resistance and therapeutic failure with agents hitting a single step along the MAPK cascade. Methods: We examined the molecular and functional effects of single and combined BRAF (dabrafenib), pan-RAF (RAF265), MEK (trametinib) and EGFR/HER2 (lapatinib) inhibition, using Western Blot and conservative isobologram analysis to assess functional synergism, and explored genetic determinants of synergistic interactions. Immunoprecipitation based assays were used to detect the interaction between BRAF and CRAF. The Mann-Whitney U test was used for comparing quantitative variables. Results: Here we demonstrated that a combination of MEK and BRAF inhibitors overcomes paradoxical MAPK activation (induced by BRAF inhibitors) in BRAF-wt/RAS-mut NSCLC and PDAC in vitro. This results in growth inhibitory synergism, both in vitro and in vivo, in the majority (65%) of the cellular models analyzed, encompassing cell lines and patient-derived cancer stem cells and organoids. However, RAS mutational status is not the sole determinant of functional synergism between RAF and MEK inhibitors, as demonstrated in KRAS isogenic tumor cell line models. Moreover, in EGFR-driven contexts, paradoxical MAPK (re)activation in response to selective BRAF inhibition was dependent on EGFR family signaling and could be offset by simultaneous EGFR/HER-2 blockade. Conclusions: Overall, our data indicate that RAF inhibition-induced paradoxical MAPK activation could be exploited for therapeutic purposes by simultaneously targeting both RAF and MEK (and potentially EGFR family members) in appropriate molecular contexts. KRAS mutation per se does not effectively predict therapeutic synergism and other biomarkers need to be developed to identify patients potentially deriving benefit from combined BRAF/MEK targeting.

AB - Background: Mounting evidence suggests that RAF-mediated MEK activation plays a crucial role in paradox MAPK (re)activation, leading to resistance and therapeutic failure with agents hitting a single step along the MAPK cascade. Methods: We examined the molecular and functional effects of single and combined BRAF (dabrafenib), pan-RAF (RAF265), MEK (trametinib) and EGFR/HER2 (lapatinib) inhibition, using Western Blot and conservative isobologram analysis to assess functional synergism, and explored genetic determinants of synergistic interactions. Immunoprecipitation based assays were used to detect the interaction between BRAF and CRAF. The Mann-Whitney U test was used for comparing quantitative variables. Results: Here we demonstrated that a combination of MEK and BRAF inhibitors overcomes paradoxical MAPK activation (induced by BRAF inhibitors) in BRAF-wt/RAS-mut NSCLC and PDAC in vitro. This results in growth inhibitory synergism, both in vitro and in vivo, in the majority (65%) of the cellular models analyzed, encompassing cell lines and patient-derived cancer stem cells and organoids. However, RAS mutational status is not the sole determinant of functional synergism between RAF and MEK inhibitors, as demonstrated in KRAS isogenic tumor cell line models. Moreover, in EGFR-driven contexts, paradoxical MAPK (re)activation in response to selective BRAF inhibition was dependent on EGFR family signaling and could be offset by simultaneous EGFR/HER-2 blockade. Conclusions: Overall, our data indicate that RAF inhibition-induced paradoxical MAPK activation could be exploited for therapeutic purposes by simultaneously targeting both RAF and MEK (and potentially EGFR family members) in appropriate molecular contexts. KRAS mutation per se does not effectively predict therapeutic synergism and other biomarkers need to be developed to identify patients potentially deriving benefit from combined BRAF/MEK targeting.

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KW - Paradoxical effect

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