A Novel Inhibitor of Topoisomerase I Is Selectively Toxic for a Subset of Non-Small Cell Lung Cancer Cell Lines

The Novel Anti-cMet Antibody seeMet 12 Potentiates Sorafenib Therapy and Radiotherapy in a Colorectal Cancer Model

Rational

cMet is abnormally regulated in gastrointestinal cancer, and is associated with increased invasiveness of the disease and poor overall survival. There are indications that targeted therapy against cMet, alone or in combination with additional cancer therapies, can help improve treatment outcome. Thus, in the present study we investigated the therapeutic efficacy of a novel cMet-targeting antibody therapy in gastrointestinal cancer models, and assessed potential augmenting effects in combination with tyrosine kinase inhibitor (TKI) targeted therapy or radiotherapy.

Methods

Three different cMet-targeting antibodies were first characterized with respect to antigen binding and effects on cell viability in vitro. The best performing candidate seeMet 12 was then further assessed for effects on colorectal cancer cell growth, proliferation and migration. Combinations with the TKI-inhibitor sorafenib or external beam radiotherapy were then evaluated for potential additive or synergistic effects in vitro using monolayer- and multicellular tumor spheroid assays. Finally, the combination of seeMet 12 and radiotherapy was evaluated in vivo in a proof-of-concept colorectal cancer xenograft study.

Results

Dose-dependent therapeutic effects were demonstrated for all three cMet-targeting antibodies. Monotherapy using seeMet 12 resulted in impaired cellular migration/proliferation and reduced tumor spheroid growth. Moreover, seeMet 12 was able to potentiate therapeutic effects in vitro for both sorafenib and radiotherapy treatments. Finally, the in vivo therapy study demonstrated promising results, where a combination of seeMet 12 and fractionated radiotherapy increased median survival by 79% compared to radiotherapy alone, and tripled maximum survival.

Conclusion

The novel anti-cMet antibody seeMet 12 demonstrated therapeutic effects in cMet positive gastrointestinal cancer cells in vitro. Moreover, the addition of seeMet 12 augmented the effects of sorafenib and radiotherapy. An in vivo proof-of-concept study of seeMet 12 and radiotherapy further validated the results. Thus, cMet-targeted therapy should be further explored as a promising approach to increase therapeutic effects, circumvent treatment resistance, and reduce side effects.

Assessment of the chemotherapeutic potential of a new camptothecin derivative, ZBH-1205

CPT-11 (irinotecan) is a derivative of camptothecin which is a natural product derived from the Chinese tree Camptotheca acuminta and widely used in antitumor therapy. Here, the in vitro anti-tumor activity and associated mechanisms of a novel derivative of camptothecin, ZBH-1205, were investigated in a panel of 9 human tumor cell lines, as well as in HEK 293 and SK-OV-3/DPP, a multi-drug resistant (MDR) cell line, and compared to CPT-11 and 7-ethyl-10-hydroxy-camptothecin (SN38). Comparisons between the different compounds were made on the basis of IC50 values as determined by the MTT assay, and flow cytometry was used to evaluate cell cycle progression, apoptosis, and the levels of pro- and active caspase-3 among different treatment groups. Interaction between the molecules and topoisomerase-1 (Topo-1)-DNA complexes was detected by a DNA relaxation assay. Our results demonstrated that IC50 values for ZBH-1205 ranged from 0.0009 μmol/L to 2.5671 μmol/L, which were consistently lower than IC50 values of CPT-11 or SN38 in the panel of cell lines, including SK-OV-3/DPP. Furthermore, ZBH-1205 was more effective than CPT-11 or SN38 at stabilizing Topo-1-DNA complexes and inducing tumor cell apoptosis. Therefore, ZBH-1205 is a promising chemotherapeutic agent to be further assessed in large-scale clinical trials.