Carboxyamidotriazole Orotate Research Articles

Carboxyamidotriazole Orotate plus TMZ Is Safe and Active in Glioblastoma

Abstract Carboxyamidotriazole orotate (CTO) plus temozolomide (TMZ) was well tolerated in patients with glioma.

Phase IB trial of carboxyamidotriazole orotate (CTO) and radiotherapy (RT) with concurrent and adjuvant temozolomide (TMZ) in newly diagnosed glioblastoma (GBM).

2060Background: CTO is an oral inhibitor of non-voltage-dependent calcium signaling achieving simultaneous modulation of several receptor-mediated signaling pathways. A single-agent phase I trial d...

Multicenter Phase IB trial of carboxyamidotriazole orotate (CTO) combined with temozolomide (TMZ) for recurrent glioblastoma (GBM) and other malignant gliomas (MG).

2064Background: CTO is an oral inhibitor of non-voltage-dependent calcium signaling that results in simultaneous modulation of several receptor-mediated calcium-dependent signaling pathways. This s...

Carboxyamidotriazole orotate (CTO) in combination with bevacizumab (BEV) for adult patients with recurrent malignant glioma post-BEV failure: Phase 1.

2067 Background: BEV is approved for the treatment of recurrent glioblastoma pts, but there is a lack of effective therapies once a tumor recurs on BEV. CTO, an oral inhibitor of non-voltage-depend...

Phase 1 clinical trial of carboxyamidotriazole orotate (CTO) in combination with lomustine (CCNU) for adult patients with recurrent malignant glioma (MG).

e13004 Background: CTO is an oral inhibitor of non-voltage-dependent calcium signaling, which modulates several pathways (EGFR, MEK, RAS, HDAC, HSP90, WNT/B-catenin, Akt, ERK, VEGF, Bcr-Abl). We po...

Phase IB trial of carboxyamidotriazole orotate (CTO) and radiotherapy (RT) with concurrent and adjuvant temozolomide (TMZ) in newly diagnosed glioblastoma (GBM).

Phase IB trial of carboxyamidotriazole orotate (CTO) and radiotherapy (RT) with concurrent and adjuvant temozolomide (TMZ) in newly diagnosed glioblastoma (GBM).

Effect of Carboxyamidotriazole Orotate, a Modulator of Calcium-Dependent Signaling Pathways, on Advanced Solid Tumors

Pre-clinical studies suggest carboxyamidotriazole orotate (CTO) demonstrates anti-tumor activity through modulation of multiple tyrosine kinase signaling pathways and interactions with the tumor microenvironment. We determined the safety and tolerability, pharmacokinetic profile, maximum tolerated dose, and recommended Phase II dose of CTO monotherapy in patients with advanced solid tumors. In this first-in-human Phase I clinical trial, eligible patients with advanced solid tumors were enrolled to receive a once-daily dose of CTO following a standard 3 + 3 Phase I design (starting at 50 mg/m2/day) with dose escalations of 30% - 100%. Dose limiting toxicity (DLT) was defined in the first cycle of treatment. Measurable disease and response were defined by RECIST version 1.1. Forty-four patients were evaluable for safety. CTO-related grade 3 toxicities included diarrhea (2.5%), fatigue (5.0%), lymphopenia (2.5%) and transient creatine phosphokinase (CPK) elevation (2.5%). There were no grade 4 or 5 toxicities. Steady state plasma levels of CAI (CTO metabolite) were achieved by day 12 with a half life estimate of 55 hr. Although no objective response rates were observed, nine patients with rapidly progressive and treatment-refractory tumors achieved stable disease (SD) durable for up to 14 months. The maximum tolerated dose for CTO alone was 427 mg/m2/day. The dose-limiting toxicity was grade 3 fatigue. CTO is orally bioavailable, safe, well tolerated and produces disease stabilization in a broad range of heavily treated refractory tumors. Combination trials of CTO with other antineoplastic agents are ongoing.

Phase IB trial of carboxyamidotriazole orotate (CTO) and temozolomide for recurrent malignant glioma (MG): A novel mechanism for modulation of multiple oncogenic pathways.

2071 Background: A possible mechanism of resistance to targeted therapeutics is the existence of redundant signaling pathways. CTO is an oral inhibitor of non-voltage-dependent calcium signaling re...

Abstract A233: Pharmacodynamic Transcriptional markers of carboxyamidotriazole orotate (CTO) exposure in anagen hair.

Abstract Background: Carboxyamidotriazole Orotate (CTO) is the orotic acid salt of carboxyamodotriazole (CAI)which is an inhibitor of calcium -dependent intracellular and extracellular signal transduction pathways, also possessing antiproliferative, antiangiogenic and anti-invasive properties. The activity of CTO alone and combination with temozolomide or 5-fluorouracil was demonstrated in human glioblastoma, melanoma and colon tumor xenografts. In Phase I (NCT01107522), nine patients pretreated with 2 to 8 targeted and non-targeted drugs and having refractory tumors responded to CTO at doses ranging 75mg/m2/day through 427mg/m2/day, and achieved stable disease for different periods (3 to 14 months). Four pretreated tumors were found to have different genomic mutations (PI3KCA, EGFR multiple, BRAFV600 and NRAS) consistent with CTO's suggested mechanism of action to inhibit multiple tyrosine kinases in addition to modulating calcium signaling pathways and calcium-dependent signal transduction pathways, as yet uncharacterized. Method: Using Epistem's ex vivo plucked anagen hair assay platform global gene expression evaluation by microarray analysis was performed to assess transcriptional response to varying doses of CTO (2, 5 and10 μM). Plucked anagen scalp hairs from five healthy donors were exposed to varying doses of CTO over a 24 hr period. Total RNA was isolated form the hair bulbs post culture and used to assess global transcriptional alterations. Results:Significant biologically relevant alteration of the anagen hair bulb transcriptome, ranging from -100 fold to +25 fold differential expression of some mRNAs was observed at CTO levels shown to be clinically relevant. Importantly, transcriptional signatures associated with inhibition of EGFR, MEK, HDAC and HSP90 were strongly suppressed at all doses of CTO. In addition, genes associated with non-voltage dependent calcium signaling were strongly suppressed, together with those associated with RAS and Growth Factor Signature. Modest suppression of transcription signatures of WNT signaling was evident at longer CTO exposure. In contrast, activation of tumor suppressor signatures associated with P53 was observed. Conclusion: These data provide multiple pharmacodynamics markers associated with the suggested mechanism of action of CTO e.g., inhibition of genes of non-voltage dependent calcium signaling and multiple onco-pathways, and also activation of signatures associated with tumor suppressors. These results in the anagen hair assay may provide the molecular MOA of CTO's observed clinical benefit in a broad spectrum of malignant tumors with different genomic types and a tool to design customized combination therapies of CTO with other agents. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A233. Citation Format: Rashida A. Karmali, Gino Miele. Pharmacodynamic Transcriptional markers of carboxyamidotriazole orotate (CTO) exposure in anagen hair. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A233.

A phase I study of carboxyamidotriazole orotate (CTO) in of advanced solid tumors.

2518 Background: CTO is an orotate salt of carboxyamidotriazole (CAI), which is an inhibitor of calcium-dependent intracellular and extracellular signal transduction pathways (presumably affecting VEGF and PI3K) and has tumor anti-proliferative and anti-invasive properties. The activity of CTO alone and in combination with temozolomide or 5Efluorouracil was demonstrated in human glioblastoma, melanoma, and colon tumor xenografts. Methods: This study assessed the maximum tolerated dose (MTD), safety, pharmacokinetics and activity of CTO monotherapy in 34 patients (pts) with advanced solid tumors meeting eligibility criteria with adequate organ function. The CTO study NCT01107522 enrolled pts in 8 cohorts receiving continuous daily oral CTO capsules at doses ranging from 50mg- 555mg/m2/day. The MTD has not been determined. Pharmacokinetic (PK) sampling was performed during cycle 1 at each dose level. CT scans were performed at baseline and after 8 weeks to assess anti-tumor effect. Patients remained on study if they achieved stable disease (SD) or tumor response and did not experience dose limiting toxicities (DLT). Results: The most frequently recorded adverse events (Grade 1 and 2) were fatigue, nausea, vomiting, and dizziness. DLTs of grade 3 fatigue (219 mg/m2) and grade 3 creatine kinase elevation (555 mg/m2) occurred in one pt each. No cardiac QTc prolongations have been recorded. PK data demonstrated therapeutically relevant CAI levels beginning at the 219mg/m2 dose. Nine pts continued CTO dosing beyond 2 cycles. Tumor assessments demonstrated SD at different doses of CTO: i) 75mg/m2 renal carcinoma (1, 12 cycles); ii) 219 mg/m2-small cell lung cancer (1, 4 cycles), squamous cell lung cancer with PIK3CA mutation (1, 10 cycles and continuing), and lung adenocarcinoma with EGFR mutation (1, 10 cycles and, continuing); iii) 285 mg/m2-1 colon cancer with BRAFV600E mutation (1, 6 cycles), and squamous cell carcinoma (tonsil) with PI3KCA and NRAS mutations (1, 9 cycles, and continuing). Conclusions: CTO given as monotherapy up to 555mg/m2/day is safe and tolerable and without MTD. Six patients with different malignancies and genomic markers achieved SD; combinatorial investigations in malignant gliomas have started. Clinical trial information: NCT01107522.

Treatment with Paclitaxel Orotate and Carboxyamidotriazole Orotate in SC-Implanted OVCAR-5 Human Ovarian Tumor Xenografts

Background: Paclitaxel (PTX) is approved for the treatment of refractory ovarian cancer and breast cancer, but is problematic due to severe, dose-dependent, potentially irreversible neurotoxicity. Alternative formulations using nanoparticles and liposomes have been developed to avoid solvent-related toxicity. These formulations allow improved delivery; however, toxicity, compensatory signaling, and drug resistance still pose challenges. Conversion of cytotoxic agents to their orotate compounds offers a potentially improved approach by increasing bioavailability and reducing toxicity. Orotate salts are neutral and acquire lipophilic properties, easing diffusion through lipid membranes. The orotate salt of PTX (PTXO) may yield an improved safety profile. Combination therapy with cytotoxic drugs, antiangiogenics and/or signal transduction pathway inhibitors has shown better efficacy than cytotoxic monotherapy. The combination of carboxyamidotriazole orotate (CTO, a calcium signal transduction pathway inhibitor) and PTX may be more effective than PTX alone at non-toxic doses. Materials and Methods: PTXO alone, and combinations of CTO with PTX and PTXO were first tested in female athymic NCr-nu/nu mice to evaluate tolerance of the combinations. The tolerated combinations, PTX monotherapy, and PTXO monotherapy were then tested to evaluate their antitumor activity in female athymic NCr-nu/nu mice with subcutaneously implanted OVCAR-5 human ovarian tumor. Antitumor activity was measured by median time to doubling, median tumor growth delay, and mean percent body weight loss. Results: CTO, PTX, and PTXO showed significant inhibition of growth of the human OVCAR-5 ovarian tumor xenografts. The combination of low PTX and CTO, or high PTXO monotherapy, had significant efficacy and it was less toxic than high PTX as measured by body weight loss. Conclusions: Low-dose CTO is effective and has low toxicity, suggesting the potential for maintenance therapy for ovarian cancer. PTXO offers efficacy and a strategy for minimizing body weight loss, and may improve outcomes for patients who demonstrate toxicity to PTX.

Combinatorial treatment with carboxyamidotriazole- orotate and temozolomide in sc-implanted human LOX IMVI melanoma xenografts

Background: Carboxyamidotriazole orotate (CTO) is the orotic acid salt of 5-amino-1(4-(4-chlorobenzoyl)-3, 5-dichlorobenzyl)-1, 2, 3-triazole-4-carboxamide (CAI). CTO possesses increased solubility as compared to CAI as the free base. The antiproliferative and antimetastatic effects of CTO are related to inhibition of receptor-operated, calcium-channel-mediated calcium influx. CTO can inhibit calcium-sensitive signal transduction in the VEGF and the PI3K pathways, inhibition of FGF-2-induced tyrosine kinase, VEGF-mediated activation of phospholipase Cy, generation of IP3 and nitric oxide synthase activation, and induction of apoptosis in imatinib mesylate resistant CML cells by downregulating bcr-abl. Methods: Different combinations of CTO and temozolomide were first tested in female athymic NCr- nu/nu mice to evaluate tolerance of the combination. The tolerated combinations were then tested to evaluate the antitumor activity against subcutaneously implanted human LOX IMVI melanoma xenografts. Results: Oral CTO at doses of 513 or 342 mg/kg/dose Q1D × 14 resulted in inhibition of tumor growth ( p <0.001 and p =0.004). Oral TEM at doses of 90 and 60 mg/kg/dose Q4D × 3 resulted in dose-dependent inhibition of tumor growth ( p <0.001 and p <0.001). Oral CTO at 513 or 342 mg/kg/dose in combination with temozolomide 90 mg/kg/dose resulted in comparable tumor inhibition to temozolomide alone. However, oral CTO at 513 mg/kg/dose in combination with temozolomide 60mg/kg/dose resulted in additive antitumor activity compared to each drug alone. Also, CTO at 342 mg/kg/dose in combination with temozolomide 60mg/kg/dose had more than additive antitumor activity and was statistically different from the group treated with temozolomide 60 mg/kg/dose alone ( p =0.001). Conclusions: These results suggest that this combination of previously configured therapeutic doses of temozolomide with CTO enhances the sensitivity of temozolomide and may permit use of lower temozolomide doses to obtain an optimum antitumor effect in combination therapy. This dose-dilution combinatorial strategy fulfills the need for increased tumor sensitivity and efficacy. Additionally, this strategy reduces drug resistance and toxicity associated with dose dense strategy of temozolomide treatment in this melanoma model.

Carboxyamidotriazole-Orotate Inhibits the Growth of Imatinib-Resistant Chronic Myeloid Leukaemia Cells and Modulates Exosomes-Stimulated Angiogenesis

The Bcr/Abl kinase has been targeted for the treatment of chronic myelogenous leukaemia (CML) by imatinib mesylate. While imatinib has been extremely effective for chronic phase CML, blast crisis CML are often resistant. New therapeutic options are therefore needed for this fatal disease. Although more common in solid tumors, increased microvessel density was also reported in chronic myelogenous leukaemia and was associated with a significant increase of angiogenic factors, suggesting that vascularity in hematologic malignancies is a controlled process and may play a role in the leukaemogenic process thus representing an alternative therapeutic target. Carboxyamidotriazole-orotate (CTO) is the orotate salt form of carboxyamidotriazole (CAI), an orally bioavailable signal transduction inhibitor that in vitro has been shown to possess antileukaemic activities. CTO, which has a reduced toxicity, increased oral bioavailability and stronger efficacy when compared to the parental compound, was tested in this study for its ability to affect imatinib-resistant CML tumor growth in a xenograft model. The active cross talk between endothelial cells and leukemic cells in the bone marrow involving exosomes plays an important role in modulating the process of neovascularization in CML. We have thus investigated the effects of CTO on exosome-stimulated angiogenesis. Our results indicate that CTO may be effective in targeting both cancer cell growth and the tumor microenvironment, thus suggesting a potential therapeutic utility for CTO in leukaemia patients.

Combinatorial treatment using CTO with paclitaxel or paclitaxel orotate in sc-implanted human OVCAR-5 ovarian tumor model.

e15515 Background: Paclitaxel (PXL) was converted to paclitaxel orotate (PXLO). Different combinations of Carboxyamidotriazole orotate (CTO) and PXL or PXLO were first evaluated in female non-tumored athymic NCr-nu/nu mice to determine the tolerance of the combinations. The antiproliferative and antimetastatic effects of CTO are related to inhibition of receptor-operated calcium channel-mediated calcium influx. CTO can inhibit calcium sensitive signal transduction in the VEGF and the PI3K pathways, and inhibit FGF-2-induced tyrosine kinase. Methods: The antitumor effect of combinations was tested for: i) PXLO compared to PXL, ii) combinatorial effect of low (342mg/kg/dose) and high (513mg/kg/dose) doses of CTO (Q1Dx14, PO) with low (11.6 and 10mg/kg/inj, Q2Dx3/2 weeks, IV) and high (23.2 and 20mg/kg/inj, Q2Dx3/2 weeks, IV) respectively, doses of PXLO or PXL, against sc-implanted human OVCAR-5 ovarian tumor xenografts. Results: Results obtained in non-tumored mice show high PXLO plus CTO was better tolerated than high PXL plus CTO. In tumor bearing mice, oral CTO at doses of 513 or 342mg/kg/dose Q1Dx14 given alone resulted in slight inhibition of tumor growth, reaching statistical significance only when administered at a low dose (two tumor mass doubling: p=0.036 for 342mg/kg/dose). PXLO at 23.2 and 11.6mg/kg/inj. given alone inhibited tumor growth (p&lt;0.001, 0.029, respectively). PXL at 20 and 10mg/kg/inj inhibited tumor growth (p&lt;0.001 and 0.011, respectively). Since body weight loss was less with the orotate form of PXL, PXLO should be the preferred drug over PXL. Addition of oral CTO 513 or 342mg/kg/dose to PXLO 23.2 or PXL 20mg/kg/inj resulted in comparable tumor inhibition to PXLO or PXL alone. However, combination of PXLO 11.6 and PXL 10mg/kg/inj with CTO 513 or 342mg/kg/dose resulted in tumor inhibition suggesting that a low dose of PXL or PXLO may be combined with CTO to achieve tumor inhibition and to allow the use of the lower doses of PXL to reduce toxicity. Conclusions: Results suggest that PXLO is less toxic than PXL and CTO influences the sensitivity of PXL suggesting a role for combinatorial therapy with low doses of PXL and CTO in this ovarian tumor model.

Combinatorial treatment with CTO and temozolomide in sc-implanted human LOX 1MVI melanoma.

e19006 Background: Carboxyamidotriazole orotate (CTO) is the orotic acid salt of 5-amino-1.(4-(4-chlorobenzoyl)-3,5-dichlorobenzyl)-1, 2, 3-triazole-4-carboxamide. CTO possesses increased solubility. The antiproliferative and antimetastatic effects of CTO are related to inhibition of receptor –opertated calcium channel- mediated calcium influx. CTO can inhibit calcium sensitive signal transduction in the VEGF and the PI3K pathways, inhibition of FGF-2-induced tyrosine kinase, VEGF-mediated activation of phospholipase Cγ, generation of IP3 and nitric oxide synthase activation, and induction of apoptosis in imatinib mesylate resistant CML cells by downregulating bcr-abl. Methods: Different combinations of CTO and temozolomide (TEM) were first tested in female athymic NCr-nu/nu mice to evaluate tolerance of the combination. The tolerated combinations were then tested to evaluate the antitumor activity against subcutaneously –implanted human LOX 1MVI melanoma xenografts. Results: Oral CTO at doses of 513 or 342 mg/kg/dose Q1Dx14 resulted in inhibition of tumor growth (p&lt;0.001 and p=0.004). Oral TEM at doses of 90 and 60mg/kg/dose Q4Dx3 resulted in dose-dependent inhibition of tumor growth (p&lt;0.001 and p&lt;0.001). Oral CTO at 513 or 342 mg/kg/dose in combination with TEM 90mg/kg/dose resulted in comparable tumor inhibition to TEM alone. However, oral CTO at 513mg/kg/dose in combination with TEM 60mg/kg/dose resulted in additive antitumor activity compared to each drug alone. Also, CTO at 342mg/kg/dose in combination with TEM 60mg/kg/dose had more than additive antitumor activity and was statistically different from the group treated with TEM 60mg/kg/dose alone (p=0.001). Conclusions: These results suggest that CTO enhances the sensitivity of TEM and may permit use of lower doses of TEM to obtain an optimum antitumor effect in combination therapy thus reducing toxicity of high TEM doses in this melanoma model.