Sandra Strychor

Changes in Brain Energy and Phospholipid Metabolism During Development and Aging in the Fischer 344 Rat

The effects of brain development and aging on high-energy phosphate and membrane phospholipid metabolism were studied from birth to senescence in the Fischer 344 rat using 31P nuclear magnetic resonance spectroscopy. Marked developmental and smaller aging-related changes were observed in brain high-energy phosphates, phospholipid precursors and phospholipid breakdown products. The biochemical changes correlate with known histological and electrophysiological changes occurring in the brain during development (neuritic sprouting and onset of brain electrical activity) and aging (loss of dendritic processes). These findings provide a framework for interpreting the effects of physiological insults during different developmental and aging periods.

Plasma, Tumor, and Tissue Disposition of STEALTH Liposomal CKD-602 (S-CKD602) and Nonliposomal CKD-602 in Mice Bearing A375 Human Melanoma Xenografts

Purpose: S-CKD602 is a STEALTH liposomal formulation of CKD-602, a camptothecin analogue. The cytotoxicity of camptothecin analogues is related to the duration of exposure in the tumor. STEALTH liposomal formulations contain lipid conjugated to methoxypolyethylene glycol and have been designed to prolong drug circulation time, increase tumor delivery, and improve the therapeutic index. For STEALTH liposomal formulations of anticancer agents to achieve antitumor effects, the active drug must be released into the tumor extracellular fluid (ECF). Experimental Design: S-CKD602 at 1 mg/kg or nonliposomal CKD-602 at 30 mg/kg was administered once via tail vein to mice bearing A375 human melanoma xenografts. Mice (n = 3 per time point) were euthanized at 0.083 to 24 h, 48 h, and 72 h after S-CKD02 and from 0.083 to 24 h after nonliposomal CKD-602. Plasma samples were processed to measure encapsulated, released, and sum total (encapsulated plus released) CKD-602, and tumor and tissue samples were processed to measure sum total CKD-602. Microdialysis samples of tumor ECF were obtained from 0 to 2 h, 4 to 7 h, and 20 to 24 h after nonliposomal CKD-602 and from 0 to 2 h, 24 to 27 h, 48 to 51 h, and 72 to 75 h after S-CKD602. A liquid chromatography-mass spectrometry assay was used to measure the total (sum of lactone and hydroxyl acid) CKD-602. The area under the concentration-versus-time curves (AUC) from 0 to infinity and time >1 ng/mL in tumor were estimated. Results: For S-CKD602, the CKD-602 sum total AUC in plasma and tumor and the CKD-602 AUC in tumor ECF were 201,929, 13,194, and 187 ng/mL h, respectively. For S-CKD602, 82% of CKD-602 remains encapsulated in plasma. For nonliposomal CKD-602, the CKD-602 AUC in plasma and tumor and the CKD-602 AUC in tumor ECF were 9,117, 11,661, and 639 ng/mL·h, respectively. The duration of time the CKD-602 concentration was >1 ng/mL in tumor ECF after S-CKD602 and nonliposomal CKD-602 was >72 and ∼20 h, respectively. For S-CKD602, the CKD-602 sum total exposure was 1.3-fold higher in fat as compared with muscle. The ratio of CKD-602 sum total exposure in fat to muscle was 3.8-fold higher after administration of S-CKD602 compared with nonliposomal CKD-602. Conclusion: S-CKD602 provides pharmacokinetic advantages in plasma, tumor, and tumor ECF compared with nonliposomal CKD-602 at 1/30th of the dose, which is consistent with the improved antitumor efficacy of S-CKD602 in preclinical studies. The distribution of S-CKD602 is greater in fat compared with muscle whereas the distribution of nonliposomal CKD-602 is greater in muscle compared with fat. These results suggest that the body composition of a patient may affect the disposition of S-CKD602 and released CKD-602.

Phase I and Pharmacokinetic Study of Pegylated Liposomal CKD-602 in Patients with Advanced Malignancies

Purpose: S-CKD602 is a pegylated liposomal formulation of CKD602, a semisynthetic camptothecin analogue. Pegylated (STEALTH) liposomes can achieve extended drug exposure in plasma and tumor. Based on promising preclinical data, the first phase I study of S-CKD602 was done in patients with refractory solid tumors. Experimental Design: S-CKD602 was administered i.v. every 3 weeks. Modified Fibonacci escalation was used (three to six patients/cohort), and dose levels ranged from 0.1 to 2.5 mg/m2. Serial plasma samples were obtained over 2 weeks and total (lactone + hydroxyl acid) concentrations of encapsulated, released, and sum total (encapsulated + released) CKD602 measured by liquid chromatography-tandem mass spectrometry. Results: Forty-five patients (21 males) were treated. Median age, 62 years (range, 33-79 years) and Eastern Cooperative Oncology Group status, 0 to 1 (43 patients) and 2 (2 patients). Dose-limiting toxicities of grade 3 mucositis occurred in one of six patients at 0.3 mg/m2, grade 3 and 4 bone marrow suppression in two of three patients at 2.5 mg/m2, and grade 3 febrile neutropenia and anemia in one of six patients at 2.1 mg/m2. The maximum tolerated dose was 2.1 mg/m2. Partial responses occurred in two patients with refractory ovarian cancer (1.7 and 2.1 mg/m2). High interpatient variability occurred in the pharmacokinetic disposition of encapsulated and released CKD602. Conclusions: S-CKD602 represents a promising new liposomal camptothecin analogue with manageable toxicity and promising antitumor activity. Phase II studies of S-CKD602 at 2.1 mg/m2 i.v. once every 3 weeks are planned. Prolonged plasma exposure over 1 to 2 weeks is consistent with STEALTH liposomes and provides extended exposure compared with single doses of nonliposomal camptothecins.

Bidirectional pharmacodynamic interaction between pegylated liposomal CKD-602 (S-CKD602) and monocytes in patients with refractory solid tumors.

Background: STEALTH® liposomal CKD-602 (S-CKD602), a camptothecin analog, is eliminated by the reticuloendothelial system (RES), which consists of cells, including monocytes. We evaluated the relationship between monocyte and absolute neutrophil counts (ANCs) in the blood and pharmacokinetic disposition of S-CKD602 and nonliposomal CKD-602 (NL-CKD602) in patients. Methods: As part of a phase I study of S-CKD602 and phase I and II studies of NL-CKD602, the percent decreases in ANC and monocytes at their nadir were calculated. After S-CKD602, the amount of CKD-602 recovered in urine was measured. Results: For S-CKD602 in patients <60 years, the percent decrease in ANC and monocytes were 43 ± 31 and 58 ± 26%, respectively (P = 0.001). For S-CKD602 in patients ≥60, the percent decrease in ANC and monocytes were 41 ± 31 and 45 ± 36%, respectively (P = 0.50). For NL-CKD602 (n = 42), the percent decrease in ANC and monocytes were similar (P > 0.05). For S-CKD602, the relationship between the percent decrease in monocytes and CKD-602 recovered in urine was stronger in patients <60 (R2 = 0.82), compared with patients ≥60 (R2 = 0.30). Conclusions: Monocytes are more sensitive to S-CKD602, compared with neutrophils, and the increased sensitivity is related to the liposomal formulation, not CKD-602. These results suggest that monocytes engulf S-CKD602, which causes the release of CKD-602 from the liposome and toxicity to the monocytes, and that the effects are more prominent in patients <60.

Pharmacokinetic study of pegylated liposomal CKD-602 (S-CKD602) in patients with advanced malignancies

S‐CKD602 is a pegylated liposomal formulation of CKD‐602. This study is the first to evaluate the factors affecting the high interpatient variability in the pharmacokinetic disposition of S‐CKD602. S‐CKD602 was administered intravenously (i.v.) every 3 weeks as part of a phase I study. Pharmacokinetics studies of the liposomal encapsulated and released CKD‐602 in plasma were performed. The pharmacokinetic variability of S‐CKD602 is associated with both linear and nonlinear clearances. Patients ≥60 years of age have a 2.7‐fold higher exposure of S‐CKD602 as compared with patients <60 years of age (P = 0.02). Patients with a lean body composition have a higher plasma exposure of S‐CKD602 (P = 0.02). Patients who have received prior therapy with pegylated liposomal doxorubicin (PLD) have a 2.2‐fold higher exposure of S‐CKD602 as compared with patients who have not received PLD (P = 0.045). Prolonged exposure of the encapsulated drug in plasma over 1–2 weeks provides significant pharmacologic advantages. The high interpatient variability in the pharmacokinetic disposition of S‐CKD602 was associated with age, body composition, saturable clearance, and prior PLD therapy.

Phase 1 and pharmacokinetic study of everolimus, a mammalian target of rapamycin inhibitor, in combination with docetaxel for recurrent/refractory nonsmall cell lung cancer.

Everolimus is a novel inhibitor of the mammalian target of rapamycin pathway, which is aberrantly activated in nonsmall cell lung cancer (NSCLC). The authors conducted a phase 1 and pharmacokinetic study of everolimus and docetaxel for recurrent NSCLC.

Phase I Study of Veliparib (ABT-888) Combined with Cisplatin and Vinorelbine in Advanced Triple-Negative Breast Cancer and/or BRCA Mutation–Associated Breast Cancer

Purpose: Cisplatin is synergistic with vinorelbine and the PARP inhibitor veliparib, and has antineoplastic activity in triple-negative breast cancer (TNBC) and BRCA mutation–associated breast cancer. This phase I study assessed veliparib with cisplatin and vinorelbine. Experimental Design: A 3+3 dose-escalation design evaluated veliparib administered twice daily for 14 days with cisplatin (75 mg/m2 day 1) and vinorelbine (25 mg/m2 days 1, 8) every 21 days, for 6 to 10 cycles, followed by veliparib monotherapy. Pharmacokinetics, measurement of poly(ADP-ribose) in peripheral blood mononuclear cells, and preliminary efficacy were assessed. IHC and gene-expression profiling were evaluated as potential predictors of response. Results: Forty-five patients enrolled in nine dose cohorts plus five in an expansion cohort at the highest dose level and recommended phase II dose, 300 mg twice daily. The MTD of veliparib was not reached. Neutropenia (36%), anemia (30%), and thrombocytopenia (12%) were the most common grade 3/4 adverse events. Best overall response for 48 patients was radiologic response with 9-week confirmation for 17 (35%; 2 complete, 15 partial), and stable disease for 21 (44%). Germline BRCA mutation presence versus absence was associated with 6-month progression-free survival [PFS; 10 of 14 (71%) vs. 8 of 27 (30%), mid-P = 0.01]. Median PFS for all 50 patients was 5.5 months (95% confidence interval, 4.1–6.7). Conclusions: Veliparib at 300 mg twice daily combined with cisplatin and vinorelbine is well tolerated with encouraging response rates. A phase II randomized trial is planned to assess veliparibs contribution to cisplatin chemotherapy in metastatic TNBC and BRCA mutation–associated breast cancer. Clin Cancer Res; 22(12); 2855–64. ©2016 AACR.

Clove extract inhibits tumor growth and promotes cell cycle arrest and apoptosis.

Cloves (Syzygium aromaticum) have been used as a traditional Chinese medicinal herb for thousands of years. Cloves possess antiseptic, antibacterial, antifungal, and antiviral properties, but their potential anticancer activity remains unknown. In this study, we investigated the in vitro and in vivo antitumor effects and biological mechanisms of ethyl acetate extract of cloves (EAEC) and the potential bioactive components responsible for its antitumor activity. The effects of EAEC on cell growth, cell cycle distribution, and apoptosis were investigated using human cancer cell lines. The molecular changes associated with the effects of EAEC were analyzed by Western blot and (qRT)-PCR analysis. The in vivo effect of EAEC and its bioactive component was investigated using the HT-29 tumor xenograft model. We identified oleanolic acid (OA) as one of the components of EAEC responsible for its antitumor activity. Both EAEC and OA display cytotoxicity against several human cancer cell lines. Interestingly, EAEC was superior to OA and the chemotherapeutic agent 5-fluorouracil at suppressing growth of colon tumor xenografts. EAEC promoted G0/G1 cell cycle arrest and induced apoptosis in a dose-dependent manner. Treatment with EAEC and OA selectively increased protein expression of p21(WAF1/Cip1) and γ-H2AX and downregulated expression of cell cycle-regulated proteins. Moreover, many of these changes were at the mRNA level, suggesting transcriptional regulation by EAEC treatment. Our results demonstrate that clove extract may represent a novel therapeutic herb for the treatment of colorectal cancer, and OA appears to be one of the bioactive components.

Population Pharmacokinetics of Pegylated Liposomal CKD‐602 (S‐CKD602) in Patients With Advanced Malignancies

S‐CKD602 is a pegylated long‐circulating liposomal formulation of CKD‐602, a potent topoisomerase I inhibitor. A population pharmacokinetic (PK) model for encapsulated and released CKD‐602 following administration of S‐CKD602 was developed to assess factors that may influence S‐CKD602 PK. Plasma samples from 45 patients with solid tumors were collected in a phase 1 study. S‐CKD602 was administered as a 1‐hour intravenous infusion with doses ranging from 0.1 to 2.5 mg/m2. Plasma concentrations of encapsulated and released CKD‐602 were used to develop a population PK model using NONMEM. PK of encapsulated CKD‐602 was described by a 1‐compartment model with nonlinear clearance, and PK of released CKD‐602 was described by a 2‐compartment model with linear clearance for all patients. Covariate analysis revealed that tumor in the liver was a significant covariate for clearance of encapsulated CKD‐602 and that age significantly influenced the release rate of CKD‐602 from S‐CKD602. Maximum elimination rate in patients with liver tumor is 1.5‐fold higher compared with patients without liver tumor. Release rate of CKD‐602 from S‐CKD602 in patients less than 60 years old was 2.7‐fold higher compared with patients 60 years old or older. These observations have potential implications in the optimal dosing of liposomal agents.

Tumor disposition of pegylated liposomal CKD-602 and the reticuloendothelial system in preclinical tumor models

Liposomes, such as pegylated-liposomal CKD-602 (S-CKD602), undergo catabolism by macrophages and dendritic cells (DCs) of the reticuloendothelial system (RES). The relationship between plasma and tumor disposition of S-CKD602 and RES was evaluated in mice bearing A375 melanoma or SKOV-3 ovarian xenografts. Area under the concentration-time curves (AUCs) of liposomal encapsulated, released, and sum total (encapsulated + released) CKD-602 in plasma, tumor, and tumor extracellular fluid (ECF) were estimated. A375 and SKOV-3 tumors were stained with cd11b and cd11c antibodies as measures of macrophages and DC. The plasma disposition of S-CKD602 was similar in both xenograft models. The ratio of tumor sum total AUC to plasma sum total AUC was 1.7-fold higher in mice bearing human SKOV-3 xenografts, compared with A375. The ratio of tumor ECF AUC to tumor sum total AUC was 2-fold higher in mice bearing human SKOV-3 xenografts, compared with A375. The staining of cd11c was 4.5-fold higher in SKOV-3, compared with A375 (P < 0.0001). The increased tumor delivery and release of CKD-602 from S-CKD602 in the ovarian xenografts, compared with the melanoma xenografts, was consistent with increased cd11c staining, suggesting that variability in the RES may affect the tumor disposition of liposomal agents.