A phase I study of carboplatin and etoposide administered in conjunction with dipyridamole, prochlorperazine and cyclosporine A

Cancer Metabolism as a Therapeutic Target and Review of Interventions

Cancer is amenable to low-cost treatments, given that it has a significant metabolic component, which can be affected through diet and lifestyle change at minimal cost. The Warburg hypothesis states that cancer cells have an altered cell metabolism towards anaerobic glycolysis. Given this metabolic reprogramming in cancer cells, it is possible to target cancers metabolically by depriving them of glucose. In addition to dietary and lifestyle modifications which work on tumors metabolically, there are a panoply of nutritional supplements and repurposed drugs associated with cancer prevention and better treatment outcomes. These interventions and their evidentiary basis are covered in the latter half of this review to guide future cancer treatment.

The phenothiazine-class antipsychotic drugs prochlorperazine and trifluoperazine are potent allosteric modulators of the human P2X7 receptor

P2X7, an ATP-gated cation channel, is involved in immune cell activation, hyperalgesia and neuropathic pain. By regulating cytokine release in the brain, P2X7 has been linked to the pathophysiology of mood disorders and schizophrenia. We here assess the impact of 123 drugs that act in the central nervous system on human P2X7. Most prominently, the tricyclic antipsychotics prochlorperazine (PCP) and trifluoperazine (TFP) potently inhibited P2X7-mediated Ca2+ entry, dye permeation and ionic currents. In divalent cation-containing bath solutions or after prolonged incubation, ATP-evoked P2X7 currents were inhibited by 10 μM PCP. This effect was not related to dopamine receptor antagonism. Surprisingly, PCP co-applied with ATP enhanced inward currents in bath solutions with low divalent cation concentrations. Intracellular perfusion with PCP did not substitute for the extracellularly applied drug, indicating that its binding sites are accessible from the extracellular space. Since P2X7 current potentiation by PCP was voltage-dependent, at least one site may be located within the electrical field of the membrane. While the channel opening and closure kinetic was altered by PCP, the apparent affinity of ATP remained unchanged (potentiation) or changed slightly (inhibition). Measurements in human monocyte-derived macrophages confirmed the PCP-induced inhibition of ATP-evoked Ca2+ influx, Yo-Pro-1 permeability, and whole cell currents. Interestingly, neither heterologously expressed rat or mouse P2X7 nor native P2X7 in rat astrocyte cultures or in mouse bone marrow-derived macrophages were inhibited by perazines with a similar potency. We conclude that perazine-type neuroleptics are potent, but species-selective allosteric modulators of human but not murine P2X7 receptors.

Dipyridamole prevents triple-negative breast-cancer progression

Dipyridamole is a widely prescribed drug in ischemic disorders, and it is here investigated for potential clinical use as a new treatment for breast cancer. Xenograft mice bearing triple-negative breast cancer 4T1-Luc or MDA-MB-231T cells were generated. In these in vivo models, dipyridamole effects were investigated for primary tumor growth, metastasis formation, cell cycle, apoptosis, signaling pathways, immune cell infiltration, and serum inflammatory cytokines levels. Dipyridamole significantly reduced primary tumor growth and metastasis formation by intraperitoneal administration. Treatment with 15 mg/kg/day dipyridamole reduced mean primary tumor size by 67.5 % (p = 0.0433), while treatment with 30 mg/kg/day dipyridamole resulted in an almost a total reduction in primary tumors (p = 0.0182). Experimental metastasis assays show dipyridamole reduces metastasis formation by 47.5 % in the MDA-MB-231T xenograft model (p = 0.0122), and by 50.26 % in the 4T1-Luc xenograft model (p = 0.0292). In vivo dipyridamole decreased activated β-catenin by 38.64 % (p < 0.0001), phospho-ERK1/2 by 25.05 % (p = 0.0129), phospho-p65 by 67.82 % (p < 0.0001) and doubled the expression of IkBα (p = 0.0019), thus revealing significant effects on Wnt, ERK1/2-MAPK and NF-kB pathways in both animal models. Moreover dipyridamole significantly decreased the infiltration of tumor-associated macrophages and myeloid-derived suppressor cells in primary tumors (p < 0.005), and the inflammatory cytokines levels in the sera of the treated mice. We suggest that when used at appropriate doses and with the correct mode of administration, dipyridamole is a promising agent for breast-cancer treatment, thus also implying its potential use in other cancers that show those highly activated pathways.

Adenosine and adenosine uptake inhibitors potentiate the neuromuscular blocking action of rocuronium mediated by adenosine A(1) receptors in isolated rat diaphragms

BACKGROUND

Adenosine, which pre-junctionally modulates neuromuscular transmission, and adenosine uptake inhibitors, which increase extracellular adenosine, have been used clinically. We investigated the effects of adenosine, dipyridamole and midazolam on the neuromuscular blocking action of rocuronium.

METHODS

Isometric twitch tensions of rat nerve-hemidiaphragm preparations elicited by indirect (phrenic nerve) supra-maximal stimulation at 0.1 Hz were evaluated (n=6 in all data).

RESULTS

Pre-treatments with adenosine (0.1 and 1 microM) and CCPA (1 microM, adenosine A(1) receptor agonist), but not that with CGS21680 (0.5 microM, A(2) receptor agonist), shifted the rocuronium concentration-twitch tension curves to the left and decreased the rocuronium concentration for 50% twitch depression (IC(50)) compared with the control (P<0.01). The leftward shift induced by 1 microM adenosine was inhibited by pre-treatments with theophylline (50 microM, non-selective adenosine receptor antagonist) and DPCPX (0.2 microM, A(1) receptor antagonist) but not by that with DPMA (5 microM, A(2) receptor antagonist). Pre-treatments with dipyridamole and midazolam, adenosine uptake inhibitors, shifted the curve to the left and decreased IC(50) at supra-therapeutic concentrations (10 and 2.5 microM, respectively) but not at clinical concentrations (2 and 0.5 microM, respectively), and the leftward shifts were inhibited by pre-treatment with DPCPX (0.2 microM).

CONCLUSION

The results indicate that adenosine potentiates the neuromuscular blocking action of rocuronium mediated by adenosine A(1) receptors and that supra-therapeutic concentrations of dipyridamole and midazolam also potentiate the action of rocuronium by increasing endogenous adenosine concentration.

Determination of carboplatin in plasma and tumor by high-performance liquid chromatography-mass spectrometry

Carboplatin is a platinum analogue that is used in a number of chemotherapeutic regimens for solid tumors, such as lung and ovarian carcinomas. Most often characterization of carboplatin's pharmacokinetic properties is based on measurement of platinum, rather than intact carboplatin. We have developed a sensitive LC-MS method for the determination of intact carboplatin in plasma ultrafiltrate and in tumor tissue. Carboplatin was extracted from rat plasma ultrafiltrate and tumor samples using solid-phase extraction cartridges and analyzed using reversed-phase chromatography with positive electrospray ionization followed by mass spectrometric detection. Using 50 microliter of plasma ultrafiltrate or 140 microliter of tumor homogenate supernatant, the extraction afforded a recovery of 58.7 and 45.8% for plasma and tumor, respectively. The mobile phase was 5% acetonitrile in 0.5% acetic acid at 0.2 ml/min that yielded a retention time of carboplatin of 2.2 min. The method has been validated at carboplatin plasma ultrafiltrate concentrations from 0.07 to 2.5 microgram/ml, and from 0.03 to 1.3 microgram/ml in tumor homogenates. The main advantages of this method compared with earlier methods are the ability to measure intact carboplatin in a sensitive and specific manner.

Population pharmacokinetics of high-dose etoposide in children receiving different conditioning regimens

Pharmacokinetics after high-dose (HD) etoposide (Eto) (40 mg/kg i.v. once as 4-h infusion, one patient 20 mg/kg i.v. as 4-h infusion, for 3 consecutive days) were studied in 31 children and young adults (age 0.8-23.7 years, median: 8.0 years) undergoing bone marrow transplantation after different conditioning regimens. Blood samples were collected until 97 h after the end of infusion. The population analysis of the first part of data (112 samples/21 patients, well documented) served to establish the pharmacokinetic model. The same data combined with the second part of data (50 samples/10 patients, 'intention to treat') then served to calculate the final population model. Data were best described by a three-compartment model with t1/2alpha = 0.28 h +/- 3.2%, t1/2beta = 3.6 h +/- 16.9% and t1/2gamma = 44.2 h +/- 56.5%, respectively (mean(geom) +/- CV(geom)). Clearance (CL) was 15.5 ml/min/m2 +/- 30.6% (mean(geom) +/- CV(geom)) and thus at the lower range of data reported in the literature. The fraction of unbound Eto (fu) was 7.0% (4.3-11.9%) [median (range)], with high intra-individual variability. An increase in f(u) with increasing total Eto was observed. The question of a principally lower Eto CL in children, as compared to adults, after HD treatment remains open.