G-quadruplex ligand RHPS4 potentiates the antitumor activity of camptothecins in preclinical models of solid tumors

Carlo Leonetti, Marco Scarsella, Giuseppe Riggio, Angela Rizzo, Erica Salvati, Maurizio D'Incalci, Lidia Staszewsky, Roberta Frapolli, Malcolm F. Stevens, Antonella Stoppacciaro, Marcella Mottolese, Barbara Antoniani, Eric Gilson, Gabriella Zupi, Annamaria Biroccio

Research output: Contribution to journalArticlepeer-review


Purpose: The formation of G-quadruplex structures at telomeric DNA sequences blocks telomerase activity, offering an original strategy to design and develop new antitumor agents. The pentacyclic acridinium salt RHPS4 is one of the most effective and selective G4 ligands able to rapidly disrupt telomere architecture, resulting in apoptosis of cancer cells. Here, we studied the therapeutic index of RHPS4 and its integration with chemotherapeutics in preclinical model of solid tumors. Experimental Design: The antitumoral activity of RHPS4 was evaluated on human xenografts of different histotypes and compared with that of standard antineoplastic agents. Moreover, the effect of RHPS4/chemotherapeutics combinations on cell survival was studied and the most favorable combination was evaluated on tumor-bearing mice. Results: RHPS4 was active in vivo as single agent and showed a high therapeutic efficacy when compared with conventional drugs. Moreover, RHPS4 had antitumoral activity in human melanoma xenografts inherently resistant to chemotherapy and exhibited antimetastatic activity. RHPS4 also showed a strong synergistic interaction with camptothecins and this effect was strictly dependent on the drug sequence employed. Treatment of mice with irinotecan followed by RHPS4 was able to inhibit and delay tumor growth and to increase mice survival. Conclusions: Our data show that RHPS4 has a good pharmacodynamic profile and in combination therapy produces a strong antitumoral activity, identifying this drug as promising agent for clinical development.

Original languageEnglish
Pages (from-to)7284-7291
Number of pages8
JournalClinical Cancer Research
Issue number22
Publication statusPublished - Nov 15 2008

ASJC Scopus subject areas

  • Cancer Research
  • Oncology


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