Doxycycline and its quaternary ammonium derivative for adjuvant therapies of chondrosarcoma.

PURPOSE: This study was conducted during the development of innovative treatment targeting the microenvironment of chondrosarcoma. In this context, MMP inhibitors were conjugated with a quaternary ammonium (QA) function as a targeting ligand to proteoglycans of chondrosarcoma extracellular matrix. Here we report the proof of concept of this strategy applied to the MMP13 inhibitor, doxycycline (Dox). METHODS: A quaternary ammonium derivative of the MMP13 inhibitor doxycycline (QA-Dox) was synthesized, and its anticancer activity was evaluated in the Swarm rat chondrosarcoma (SRC) model compared with the parent drug doxycycline, in vitro and in vivo. In vivo, dox and QA-Dox efficiency was assessed at equimolar doses according to a q4dx4 schedule by monitoring tumour volume by MRI and PG-targeted scintigraphy. Molecular mechanism (MMP13 expression, proteoglycan level) and histology studies were performed on tumours. RESULTS: The link of QA targeting function to Dox maintained the MMP13 inhibitory activity in vitro. Interestingly, the bacteriostatic activity was lost. SRC cells incubated with both drugs were blocked in S and G2 M phases. Tumour growth inhibition (confirmed by histology) was observed for both Dox and QA-Dox. Undesirable blood effects (leukocyte decrease) were reduced when Dox was targeted to tumour tissue using the QA function. CONCLUSIONS: In the SRC model, the MMP13 inhibitor Dox and its QA derivative are promising as adjuvant therapies for chondrosarcoma management.

Proteoglycans as Target for an Innovative Therapeutic Approach in Chondrosarcoma: Preclinical Proof of Concept.

To date, surgery remains the only option for the treatment of chondrosarcoma, which is radio- and chemoresistant due in part to its large extracellular matrix (ECM) and poor vascularity. In case of unresectable locally advanced or metastatic diseases with a poor prognosis, improving the management of chondrosarcoma still remains a challenge. Our team developed an attractive approach of improvement of the therapeutic index of chemotherapy by targeting proteoglycan (PG)-rich tissues using a quaternary ammonium (QA) function conjugated to melphalan (Mel). First of all, we demonstrated the crucial role of the QA carrier for binding to aggrecan by surface plasmon resonance. In the orthotopic model of Swarm rat chondrosarcoma, an in vivo biodistribution study of Mel and its QA derivative (Mel-QA), radiolabeled with tritium, showed rapid radioactivity accumulation in healthy cartilaginous tissues and tumor after [3H]-Mel-QA injection. The higher T/M ratio of the QA derivative suggests some advantage of QA-active targeting of chondrosarcoma. The antitumoral effects were characterized by tumor volume assessment, in vivo 99mTc-NTP 15-5 scintigraphic imaging of PGs, 1H-HRMAS NMR spectroscopy, and histology. The conjugation of a QA function to Mel did not hamper its in vivo efficiency and strongly improved the tolerability of Mel leading to a significant decrease of side effects (hematologic analyses and body weight monitoring). Thus, QA conjugation leads to a significant improvement of the therapeutic index, which is essential in oncology and enable repeated cycles of chemotherapy in patients with chondrosarcoma. Mol Cancer Ther; 15(11); 2575-85. ©2016 AACR.

Stable tumor vessel normalization with pO2 increase and endothelial PTEN activation by inositol trispyrophosphate brings novel tumor treatment.

Tumor hypoxia is a characteristic of cancer cell growth and invasion, promoting angiogenesis, which facilitates metastasis. Oxygen delivery remains impaired because tumor vessels are anarchic and leaky, contributing to tumor cell dissemination. Counteracting hypoxia by normalizing tumor vessels in order to improve drug and radio therapy efficacy and avoid cancer stem-like cell selection is a highly challenging issue. We show here that inositol trispyrophosphate (ITPP) treatment stably increases oxygen tension and blood flow in melanoma and breast cancer syngeneic models. It suppresses hypoxia-inducible factors (HIFs) and proangiogenic/glycolysis genes and proteins cascade. It selectively activates the tumor suppressor phosphatase and tensin homolog (PTEN) in vitro and in vivo at the endothelial cell (EC) level thus inhibiting PI3K and reducing tumor AKT phosphorylation. These mechanisms normalize tumor vessels by EC reorganization, maturation, pericytes attraction, and lowering progenitor cells recruitment in the tumor. It strongly reduces vascular leakage, tumor growth, drug resistance, and metastasis. ITPP treatment avoids cancer stem-like cell selection, multidrug resistance (MDR) activation and efficiently enhances chemotherapeutic drugs activity. These data show that counteracting tumor hypoxia by stably restoring healthy vasculature is achieved by ITPP treatment, which opens new therapeutic options overcoming hypoxia-related limitations of antiangiogenesis-restricted therapies. By achieving long-term vessels normalization, ITPP should provide the adjuvant treatment required in order to overcome the subtle definition of therapeutic windows for in vivo treatments aimed by the current strategies against angiogenesis-dependent tumors.

First preclinical imaging of primary cartilage neoplasm and its local recurrence using 99mTc-NTP 15-5 radiotracer.

UNLABELLED: This study on a rat model of grade II chondrosarcoma aimed to determine whether the radiotracer N-(triethylammonium)-3-propyl-[15]ane-N5 radiolabeled with (99m)Tc ((99m)Tc-NTP 15-5), which binds to cartilage proteoglycans, has pathophysiologic validity for in vivo imaging of cartilage tumoral tissue. METHODS: We used 2 experimental approaches with the Swarm chondrosarcoma rat model: that is, a primary paratibial location and local recurrence after intralesional curettage. (99m)Tc-NTP 15-5 scintigraphy and (99m)Tc-hydroxymethylenediphosphonate ((99m)Tc-HMDP) scanning were performed at regular intervals during 50 d after tumor implantation in a paratibial location (primary model; n = 12 animals) and after intralesional curettage in a femoral condyle location (recurrence model; n = 9 animals). For each animal, positive scans were analyzed at each time point using the target-to-background ratio (TBR), with the target region of interest delineated over the tumor and the background region of interest over muscle. In each model, the TBR time course was followed against primary tumoral growth or recurrence. Tumor volume was monitored for 2 mo by measuring the 2 perpendicular diameters. At study end, animals were sacrificed for histopathologic analysis. RESULTS: For both models, (99m)Tc-NTP 15-5 scans showed tracer accumulation at the site of implantation or curettage. For the primary tumor model, the mean TBR was 1.6 +/- 0.14 by day 4 after implantation and increased over time as the disease progressed, with a mean TBR of 4.25 +/- 0.25 on day 45. For the recurrence model, mean TBR was 3.27 +/- 0.24 by day 4 after curettage and increased with recurrence, with a mean value of 5.25 +/- 0.49 on day 50. (99m)Tc-HMDP bone scans were negative for both models throughout the study; at a later stage of the study, an area of (99m)Tc-HMDP accumulation was seen in the diaphysis of the bone adjacent to the tumor and was attributed to remodeling. CONCLUSION: These experimental results in 2 preclinical models of grade II chondrosarcoma bring forward data in favor of (99m)Tc-NTP 15-5 radiotracer for imaging primary growth of chondrosarcoma and its local recurrence after surgery.