19P - Immunomodulation and inhibition of tumor growth by a new class of TLR9 agonists – EnanDIM

Date 05 November 2016
Event ESMO Symposium on Immuno-Oncology 2016
Session Lunch and general poster viewing
Presenter Barbara Volz
Citation Annals of Oncology (2016) 27 (suppl_8): viii4-viii17. 10.1093/annonc/mdw527
Authors B. Volz1, K. Kapp2, D. Oswald2, B. Wittig3, M. Schmidt1
  • 1Translational Research, Mologen AG, 14195 - Berlin/DE
  • 2R&d Department, Mologen AG, Berlin/DE
  • 3Foundation Institute Molecular Biology And Bioinformatics, Freie Universitaet Berlin, 14195 - Berlin/DE

Abstract

Aim/Background

Preclinical and clinical studies support the use of Toll like receptor 9 (TLR9) agonists in anti-tumor therapies based on their broad activation of the immune system. Two different families of TLR9 agonists, exhibiting non-methylated CG-motifs, are established: Covalently closed dumbbell-shaped DNA molecules with natural phosphodiester (PO) backbone which are protected from degradation by their conformation (dSLIM®) and single-stranded, oligodeoxynucleotides (CpG-ODN) commonly stabilized by phosphorothioates (PTO). However, chemical PTO modifications have resulted in an unfavorable risk-to-benefit ratio in clinical trials.

Methods

To combine the advantages of both families, a third family of TLR9 agonists (EnanDIM®), consisting of linear single-stranded ODN was developed. Protection against exonucleases is achieved by use of L-deoxyribose instead of the naturally occurring enantiomeric D-deoxyribose at their 3’-ends. EnanDIM® with varying sequences were screened for their activation of human peripheral blood mononuclear cells (PBMC) based on secretion of IFN-alpha and IP-10 as well as activation of immune cells. Selected molecules were applied to mice in a maximum feasible dose (MFD) study: After a single subcutaneous injection of 10 to 50 mg (300 to 1700 mg/kg) the acute toxicity was evaluated for 15 days. Anti-tumor efficacy of EnanDIM® was analyzed in CT26 syngeneic murine tumor studies.

Results

EnanDIM581, EnanDIM744 and EnanDIM532 were selected due to their pronounced activation of immune cells in vitro. No signs of toxicity were observed throughout the MFD study. Increase of IP-10 concentration in serum was dose-dependent, reaching a maximum 6 h post-injection and declining thereafter. First data from a murine CT26 tumor model showed that EnanDIM532 reduces tumor growth and prolongs survival of the mice. Mean tumor growth inhibition was 63.3%.

Conclusions

The new family of TLR9 agonists, EnanDIM®, broadly activates the immune system in vitro and in vivo. Even high doses of EnanDIM® resulted in no signs of toxicity in mice, whereas a reduction of tumor growth was observed in a murine CT26 tumor model in vivo. Thus EnanDIM® has the potential for clinical development in cancer treatment.

Clinical trial identification

Legal entity responsible for the study

Mologen AG

Funding

Mologen AG

Disclosure

B. Volz, K. Kapp, D. Oswald, M. Schmidt: Employee of Mologen. B. Wittig: Consultancy and shareholder of Mologen.