Satraplatin, an Oral Platinum, Administered on a Five-day Every-Five-Week Schedule: a Pharmacokinetic and Food Effect Study

Platinum Drug-Incorporating Polymeric Nanosystems for Precise Cancer Therapy

Platinum (Pt) drugs are widely used in clinic for cancer therapy, but their therapeutic outcomes are significantly compromised by severe side effects and acquired drug resistance. With the emerging immunotherapy and imaging-guided cancer therapy, precise delivery and release of Pt drugs have drawn great attention these days. The targeting delivery of Pt drugs can greatly increase the accumulation at tumor sites, which ultimately enhances antitumor efficacy. Further, with the combination of Pt drugs and other theranostic agents into one nanosystem, it not only possesses excellent synergistic efficacy but also achieves real-time monitoring. In this review, after the introduction of Pt drugs and their characteristics, the recent progress of polymeric nanosystems for efficient delivery of Pt drugs is summarized with an emphasis on multi-modal synergistic therapy and imaging-guided Pt-based cancer treatment. In the end, the conclusions and future perspectives of Pt-encapsulated nanosystems are given.

Platinum(IV) Complexes of the 1,3,5-Triamino Analogue of the Biomolecule Cis-Inositol Designed as Innovative Antineoplastic Drug Candidates

Metal complexes occupy a special place in the field of treatment and diagnostics. Their main advantages stem from the possibility of fine-tuning their thermodynamic properties and kinetic behavior in the biological milieu by applying different approaches such as properly constructed inner coordination sphere, appropriate choice of ligands, metal oxidation state, redox potential, etc., which are specific to these compounds. Here we discuss the design and synthesis of two octahedral cationic Pt(IV) complexes of the tridentate ligand all-cis-2,4,6-triaminocyclohexane-1,3,5-triol (taci) with composition, fac-[Pt(taci)I₃]⁺, 1 and bis-[Pt(taci)₂]⁴⁺, 2 as well as the potential for their application as antineoplastic agents. The complexes have been isolated in a solid state as: fac-[Pt(taci)I₃]I·3H₂O (1A), fac-[Pt(taci)I₃]I (1B), fac-[Pt(taci)I₃]I·2DMF (1C), bis-[Pt(taci)₂](CO₃)₂·6H₂O (2A) by changing the acidity of the reaction systems, the molar ratios of the reagents and the counterions, and by re-crystallization. The ligand taci is coordinated through the NH₂-groups, each molecule occupying three coordination places in the inner coordination sphere of Pt(IV). Monitoring of the hydrolysis processes of 1A and 2A at different acidity showed that while 2A remained stable over the study period, the I⁻-ions in 1A were successively substituted, with the main product under physiologically mimetic conditions being fac,cis-[Pt(taci)I(OH)₂]⁺ (h2). The antiproliferative tests involved eight cancer cell models, among which chemosensitive (derived from leukemias and solid tumors) and chemoresistant human Acute myeloid leukemia lines (HL-60/Dox, HL-60/CDDP), as well as the non-malignant kidney’ cells HEK-293T showed that the complexes 1A and 2A are characterized by a fundamentally different profile of chemosensitivity and spectrum of cytotoxic activity compared to cisplatin. The new Pt(IV) complexes were shown to be more effective in selectively inhibiting the proliferation of human malignant cells compared to cisplatin. Remarkable activity was recorded for 1A, which showed an effect (IC₅₀ = 8.9 ± 2.4) at more than 16-fold lower concentration than cisplatin (IC₅₀ = 144.4 ± 9.8) against the resistant cell line HL-60/CDDP. In parallel, 1A exhibited virtually the same cytotoxic effect against the parental HL-60 cells (IC₅₀ = 9.0 ± 1.2), where cisplatin displays comparable chemosensitivity (IC₅₀ = 8.3 ± 0.8). The determined resistance indices (RI~1) show unequivocally that the resistant lines are sensitive to both compounds tested; therefore, they are capable of overcoming the mechanisms of cisplatin resistance. The structural features of these compounds and their promising pharmacological properties justify their inclusion in the group of “non-classical metal-based antitumor compounds” and are a prerequisite for the admission of alternative mechanisms of action.

The Platin-X series: activation, targeting, and delivery

Anticancer platinum (Pt) complexes have long been considered to be one of the biggest success stories in the history of medicinal inorganic chemistry. Yet there remains the hunt for the "magic bullet" which can satisfy the requirements of an effective chemotherapeutic drug formulation. Pt(iv) complexes are kinetically more inert than the Pt(ii) congeners and offer the opportunity to append additional functional groups/ligands for prodrug activation, tumor targeting, or drug delivery. The ultimate aim of functionalization is to enhance the tumor selective action and attenuate systemic toxicity of the drugs. Moreover, an increase in cellular accumulation to surmount the resistance of the tumor against the drugs is also of paramount importance in drug development and discovery. In this review, we will address the attempts made in our lab to develop Pt(iv) prodrugs that can be activated and delivered using targeted nanotechnology-based delivery platforms.

Conjugation of platinum(IV) complexes with chlorambucil to overcome cisplatin resistance via a "joint action" mode toward DNA

Two platinum(IV) complexes were designed and prepared by conjugation of cisplatin and oxaliplatin units with a DNA-damaging agent, chlorambucil, respectively. By taking a joint action to enhance the damage of DNA, the conjugates displayed potent antitumor activity against all the tested cancer cell lines comparable to cisplatin and oxaliplatin, and notably could overcome cisplatin resistance at certain degree. Complex 4, a hybrid of cisplatin and chlorambucil, arrested the cell cycle at the S and G2 phases, distinctive from those of cisplatin and oxaliplatin. Apoptosis studies revealed that complex 4 could induce cell apoptosis significantly in both SGC7901 and SGC7901/CDDP cells. Moreover, further investigation indicated that complex 4 suppressed the drug resistance by the improvement of the platinum uptake and the inhibition of PRAP-1 protein. These results show that the "joint action" on DNA is an effective strategy to overcome cisplatin resistance.

Electrochemical Detection of Platinum(IV) Prodrug Satraplatin in Serum

We report the design and fabrication of a reagentless and reusable electrochemical sensor for detection of satraplatin (SAT), a platinum(IV) prodrug. The detection strategy is based on the electrocatalytic reaction between the Pt(IV) center of SAT and surface-immobilized methylene blue. We systematically evaluated the effect of passivating diluent chain length on the overall sensor performance. Our results show that the use of a shorter diluent like 2-mercaptoethanol is more advantageous than using a longer and more passivating diluent such as 6-mercapto-1-hexanol. Independent of the use of cyclic voltammetry or chronoamperometry as the sensor interrogation technique, all three sensors, each passivated with a different alkanethiol diluent, have been demonstrated to be sensitive; the limit of detection is in the range of 1-10 μM. They are also highly specific and do not respond to Pt(II) drugs such as cisplatin and carboplatin. More importantly, they are selective enough to be employed directly in 50% serum. This sensing strategy has potential applications in clinical pharmacokinetics studies.

Phase 1 trial and pharmacokinetic study of the oral platinum analog satraplatin in children and young adults with refractory solid tumors including brain tumors

BACKGROUND

Based on pre-clinical and clinical activity in adult refractory tumors, and absence of significant neuro-, nephro-, or oto-toxicity, we conducted a pediatric phase 1 trial to determine the toxicities, maximum tolerated dose (MTD), and pharmacokinetics of satraplatin, an oral platinum analogue, in children and young adults with refractory solid tumors.

PROCEDURE

Satraplatin was administered orally once daily on days 1-5 of a 28-day cycle at dose level (DL) 1 (60 mg/m(2) /dose), and DL2 (80 mg/m(2) /dose). Toxicities, responses, satraplatin pharmacokinetics, and pharmacogenomic expression of specific DNA repair genes were evaluated.

RESULTS

Nine patients received 1-15 cycles (median = 2). The MTD was exceeded at DL2 with delayed prolonged myelosuppression as dose-limiting toxicity (DLT) in 2/4 patients. At DL1, 0/5 patients had DLTs. Common non-DLTs included myelosuppression, gastrointestinal toxicities, fatigue, headache, liver enzyme elevation, and electrolyte abnormalities. No significant neuro-, nephro-, or oto-toxicity was observed. No objective responses were observed but 2 patients experienced prolonged disease stabilization (---6-15 cycles). Satraplatin exposure (day 1 plasma ultrafiltrate area under the curve) was similar at DL1 and DL2. A strong correlation between estimated creatinine clearance and satraplatin pharmacokinetic parameters (clearance, area under the curve, and peak concentration) was observed.

CONCLUSIONS

The MTD of oral satraplatin in children with solid tumors was 60 mg/m(2) /dose daily ×5 days every 28 days, which is lower than the adult recommended dose of 80-120 mg/m(2) /dose. The toxicity profile was similar to adults and delayed myelosuppression was the DLT. No significant neuro-, nephro- or oto-toxicities were observed.

Drug interactions and the pharmacist: focus on everolimus

OBJECTIVE

To evaluate everolimus drug-drug and drug-food interactions, with an emphasis on patients with cancer.

DATA SOURCES

Literature was accessed through PubMed (1990-March 2013) using Boolean combinations of the terms drug interactions, herb-drug interactions, food-drug interactions, everolimus, antineoplastic agents, hormonal, and breast neoplasms. In addition, reference citations from publications and the prescribing information for everolimus were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All articles published in English, including human, animal, and in vitro studies, identified from the data sources were included.

DATA SYNTHESIS

Patients with cancer are at increased risk for drug interactions because of the multiple medications they are prescribed to treat their disease and comorbid conditions. Everolimus, an oral mammalian target of rapamycin (mTOR) inhibitor, is indicated for the treatment in adults with progressive neuroendocrine tumors of pancreatic origin that are unresectable, locally advanced, or metastatic; adults with advanced renal cell carcinoma after failure of treatment with sunitinib or sorafenib; and, recently, postmenopausal women with advanced hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer in combination with exemestane after failure of treatment with letrozole or anastrozole. As its use increases among patients with cancer, clinicians must be knowledgeable about potential drug and/or food/nutrient interactions and the mechanisms by which these interactions occur, to mitigate and prevent unwanted reactions and ensure patient safety.

CONCLUSIONS

Everolimus is a widely used oral mTOR inhibitor that has the potential for drug interactions that may affect therapeutic outcomes, produce toxicities, or both. This article provides a review of evidence-based literature, along with the prescribing information, to educate clinicians on the significance of these drug interactions and their impact on management with everolimus.

An open-label, dose-finding study of the combination of satraplatin and gemcitabine in patients with advanced solid tumors

Purpose: Satraplatin is a third generation oral platinum, which has demonstrated antitumor activity. The aim of this phase I study was to determine the maximum tolerated dose (MTD) of the combination of satraplatin and gemcitabine in patients previously treated with chemotherapy and in patients without prior chemotherapy. Patients and Methods: Two separate MTDs were planned in two different patient groups (those with and without prior chemotherapy treatment). Dose escalations were planned in cohorts of three patients. Tumor measurements were obtained every two cycles. Assessment of response was performed according to Response Evaluation Criteria in Solid Tumors (RECIST criteria v.1.0). Results: Thirty subjects were enrolled. A MTD of gemcitabine 1000 mg/m² days 1 and 8 plus satraplatin 60 mg/m² days 1–3, every 21 days was determined in the prior chemotherapy group. No MTD could be determined for the no prior chemotherapy group treated with this schedule. Five patients completed 12 treatment cycles; 22 serious adverse events (SAE) were observed. Although not an entry criteria, overall confirmed response was observed in 17 (24%) evaluable patients (complete response, CR = 1 and partial response, PR = 3) and in 3/7 (43%) patients with measure prostate cancer lesions. Conclusions: In this phase Ib study, the combination of satraplatin and gemcitabine demonstrated to be safe and efficacious in particular in patients with prostate cancer.

Novel oral anticancer drugs: a review of adverse drug reactions, interactions and patient adherence

Each aspect of oncological care is widely affected by the spread of oral anticancer agents, which raises several questions in terms of safe medication use and patient adherence. Over the past decade targeted therapies have appeared in clinical practice and revolutionized the pharmacological treatment of malignancies. Regular patient – doctor visits and proper patient education is crucial in order to comply with the therapy previously agreed upon with the oncologist, to increase patient adherence, to detect and to treat adverse effects in early stages. Since the information on the new medicines in Hungarian language is sparse it is the intention of the authors to give an overview of the basic knowledge, patient safety issues, adverse effects and interactions. Official drug information summaries and data on pharmacokinetics, interactions and adverse effects from the literature are reviewed as the basis for this overview. Orv. Hetil., 2012, 153, 66–78.

Clinical and pharmacokinetic evaluation of satraplatin

INTRODUCTION

The toxicities of cisplatin, that is, nephrotoxicity, neurotoxicity and emesis, provided the impetus for the development of more tolerable platinum analogs. Satraplatin is an investigational third-generation orally available lipophilic platinum, which has demonstrated safety and antitumor activity in multiple settings.

AREAS COVERED

The clinical activity of satraplatin in metastatic castrate-resistant prostate cancer (mCRPC), breast, lung and other advanced solid tumors is discussed with a focus on its pharmacokinetic properties. The article was formulated using publications found through PubMed search in addition to presentations given at major conferences.

EXPERT OPINION

Satraplatin was associated with dose-limiting myelosuppression, but no significant ototoxicity, neurotoxicity or nephrotoxicity. Despite the activity of satraplatin in mCRPC, survival was not extended in an unselected population included in a Phase III trial. While further development of satraplatin in large Phase III trials is not planned at this time, efforts are ongoing to develop tailored therapy in mCRPC based on excision repair cross-complementing group 1 expression or BRCAness. Moreover, based on potentially better central nervous system penetration due to lipophilicity, evaluation in patients with brain tumors is ongoing. Given the favorable toxicity profile and convenient oral administration, satraplatin may warrant development in settings that preclude cisplatin, for example, underlying renal dysfunction, elderly age and poor performance status.

Phase I study of the effects of renal impairment on the pharmacokinetics and safety of satraplatin in patients with refractory solid tumors

BACKGROUND

Satraplatin is an oral platinum analog with demonstrated activity in a range of malignancies. The current study was designed to evaluate the effect of varying degrees of renal impairment on the safety and pharmacokinetics (PKs) of satraplatin.

PATIENTS AND METHODS

Patients with advanced solid tumors, refractory to standard therapies, were eligible. The study included four cohorts of patients with varying levels of renal function, and eight patients per cohort: Group 1 (G1) = normal renal function; G2 = mild renal impairment [creatinine clearance (CrCl) 50-80 ml/min]; G3 = moderate impairment (CrCl 30 to <50 ml/min); G4 = severe impairment (CrCl <30 ml/min). Satraplatin was administered orally at 80 mg/m(2)/day on days 1-5 every 35 days.

RESULTS

A total of 32 patients were enrolled, 8 patients in each renal function group. Each group tolerated the dose of 80 mg/m(2)/day on days 1-5 every 35 days without the need for dose deescalation. The most common adverse events were fatigue (63%), nausea (56%), diarrhea (53%), anorexia (47%), constipation (38%), vomiting (28%), anemia, dyspnea, and thrombocytopenia (25%). There were no dose-limiting toxic effects in any study group. There was increased exposure to plasma platinum and plasma ultrafiltrate platinum in patients with moderate to severe renal impairment.

CONCLUSIONS

Satraplatin PKs was altered in patients with renal impairment. However, a corresponding increase in satraplatin-related toxic effects was not observed.

Organic Anion Transporting Polypeptide 5A1 (OATP5A1) in Small Cell Lung Cancer (SCLC) Cells: Possible Involvement in Chemoresistance to Satraplatin

BACKGROUND

The role of organic anion transporting polypeptide 5A1 (OATP5A1) a member of a family of drug transporters that mediate cellular uptake of drugs has not been characterized so far.

METHODS

Gene expression levels of OATP5A1 in small cell lung cancer (SCLC) cell lines were determined by real-time qPCR and chemosensitivity of HEK-293-SLCO5A1-transfected cells to satraplatin in MTT assays.

RESULTS

Significant expression of this transporter was found at the mRNA level, primarily in drug-resistant SCLC cells, and SLCO5A1-transfected HEK-293 cells showed higher resistance to satraplatin. OATP5A1 is found preferentially in cytoplasmic membranes of tumor cells, including SCLC.

CONCLUSIONS

OATP5A1 seems to effect intracellular transport of drugs and may participate in chemoresistance of SCLC by sequestration, rather than mediating cellular uptake. Since satraplatin failed to improve survival in SCLC patients, the relation of OATP5A1 expression to clinical drug resistance and its use as marker of chemoresistance should be further investigated.