A phase I study of 4'-0-tetrahydropyranyladriamycin. Clinical pharmacology and pharmacokinetics

Selecting ideal drugs for encapsulation in thermosensitive liposomes and other triggered nanoparticles

OBJECTIVE

Thermosensitive liposomes (TSL) and other triggered drug delivery systems (DDS) are promising therapeutic strategies for targeted drug delivery. However, successful designs with candidate drugs depend on many variables, including nanoparticle formulation, drug properties, and cancer cell properties. We developed a computational model based on experimental data to predict the potential efficacies of drugs when used with triggered DDS, such as TSL.

METHODS

A computer model based on the Krogh cylinder was developed to predict uptake and cell survival with four anthracyclines when delivered by intravascular triggered DDS (e.g., TSL): doxorubicin (DOX), idarubicin (IDA), pirarubicin (PIR), and aclarubicin (ACLA). We simulated three tumor types derived from SVR angiosarcoma, LLC lung cancer, or SCC-1 oral carcinoma cells. In vitro cellular drug uptake and cytotoxicity data were obtained experimentally and incorporated into the model.

RESULTS

For all three cell lines, ACLA and IDA had the fastest cell uptake, with slower uptake for DOX and PIR. Cytotoxicity was highest for IDA and lowest for ACLA. The computer model predicted the highest tumor drug uptake for ACLA and IDA, resulting from their rapid cell uptake. Overall, IDA was most effective and produced the lowest tumor survival fraction, with DOX being the second best. Perivascular drug penetration was reduced for drugs with rapid cell uptake, potentially limiting delivery to cancer cells distant from the vasculature.

CONCLUSION

Combining simple in vitro experiments with a computer model could provide a powerful screening tool to evaluate the potential efficacy of candidate investigative drugs preceding TSL encapsulation and in vivo studies.

Extract from Dioscorea bulbifera L. rhizomes aggravate pirarubicin-induced cardiotoxicity by inhibiting the expression of P-glycoprotein and multidrug resistance-associated protein 2 in the mouse liver

Chinese herbal medicine is widely used because it has a good safety profile and few side effects. However, the risk of adverse drug reactions caused by herb-drug interactions (HDIs) is often overlooked. Therefore, the task of identifying possible HDIs and elucidating their mechanisms is of great significance for the prevention and treatment of HDI-related adverse reactions. Since extract from Dioscorea bulbifera L. rhizomes (DB) can cause various degrees of liver damage, it is speculated that HDIs may occur between DB extract and chemicals metabolized or excreted by the liver. Our study revealed that the cardiotoxicity of pirarubicin (THP) was increased by co-administration of DB, and the expression of P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (Mrp2) in the liver was inhibited by DB extract, which led to the accumulation of THP in heart tissue. In conclusion, there are risks of the co-administration of DB extract and THP. The mechanism of HDIs can be better revealed by targeting the efflux transporters.

Pharmacokinetics and metabolism of pirarubicin in humans: correlation with pharmacodynamics

The pharmacokinetic monitoring of anthracycline-containing regimens is warranted because of the important toxicity of these drugs and because pharmacokinetic-pharmacodynamic relationships have been clearly established. We studied the pharmacokinetics of the new anthracycline pirarubicin in 80 courses of treatment performed in 27 patients, using a limited sampling protocol we had previously validated. We observed (for 47 of these courses) a significant correlation between the leucocyte cell kill and the pirarubicin area under the time x concentration curve, but the most significant correlation was obtained using the plasma concentration of doxorubicin, a metabolite of pirarubicin, at the end of the infusion. On the basis of this value, it is possible to predict for pirarubicin haematological toxicity in a way that can help the clinician in identifying patients at risk for toxicity.

Pharmacokinetics of 4'-O-tetrahydropyranyladriamycin given on a weekly schedule in patients with advanced breast cancer

Improved quality of life has gained importance over shortly lasting remissions in yet incurable metastatic breast cancer. Fractionation of drug administration is one of the possible approaches to reduce the concentration-dependent toxicity of anthracyclines. We evaluated the pharmacokinetics of 4'-O-tetrahydropyranyladriamycin (THP-ADM) under weekly administration in patients with advanced breast cancer (dose escalation, from 20 to 27 mg/m2 THP-ADM). The concentration-time curves of THP-ADM in plasma were best described by an open three-compartment model [half-life of the first disposition phase (t1/2 alpha), 3.15 min; terminal elimination half-life (t1/2 gamma), 13.9 h] with a mean area under the curve (AUC) of 12.2 ng h ml-1mg-1 m-2, resulting in a mean plasma clearance of 86.9 1h-1 m-2. Metabolism included the formation of Adriamycin (ADM), Adriamycinol (ADM-OH), 13-dihydro-4'-O-tetrahydropyranyladriamycin (THP-OH), 7-deoxyadriamycinone (7H-ADn), and 7-deoxy-13-dihydroadriamycinone (7H-ADn-OH), with maximal plasma concentrations ranging from 2.8 to 5.5 ng/ml. The mean total amount of cytotoxic anthracyclines excreted into urine, mainly as the parent drug, was 5% of the delivered dose. ADM and ADM-OH, but not the parent drug, were observed in urine at up to 4 weeks after the last therapeutic cycle. There was a significant correlation between the leukocyte nadir under therapy and the AUC of ADM-OH (r = 0.800, P < 0.05). Since no shift in the plasma kinetics was observed from the first to the sixth cycle, the favorable ratio of the AUCs of THP-ADM and ADM after fractionation of THP-ADM suggests lower toxic side effects attributable to ADM. This hypothesis was confirmed in a clinical study, where no severe cardiotoxicity and only mild alopecia were observed in 19 patients. Thus, pharmacokinetics studies might be helpful in both individualization of therapy with THP-ADM and optimization of the administration schedule.

A limited sampling strategy for the study of pirarubicin pharmacokinetics in humans

Pirarubicin (4'-O-tetrahydropyranyldoxorubicin, THP-Adriamycin) is a new anthracycline antibiotic that has recently been developed because its reduced cardiac toxicity is associated with an antitumour efficacy similar to that of doxorubicin. Pirarubicin is characterised by strong haematological toxicity, which has been shown to be correlated with pharmacokinetic parameters, especially the area under the time-concentration curve. To obtain routine pharmacokinetic evaluations of pirarubicin for dose monitoring we developed a limited sampling strategy relying on three blood samples taken at the end of the infusion and at 12 and 24 h post-infusion. The characteristics of interindividual variability were assessed on the first courses of treatment performed in 18 patients; the model was then validated on 10 independent first courses of treatment performed in 10 other patients. The main pharmacokinetic parameters (half-lives, total volume of distribution, total plasma clearance) were estimated in the test group by maximum-likelihood estimation using all samples and by Bayesian estimation using three samples. The concordance between the two estimates was correct (the bias and precision for clearance were 2.3% and 12.1%, respectively), which shows that this limited sampling strategy can be used in routine drug monitoring.

Phase II study of pirarubicin combined with cisplatin in recurrent ovarian cancer

Although 50%-80% of patients with advanced ovarian cancer demonstrate an objective response after platinum-based chemotherapy, a majority of these patients will ultimately experience a relapse of their disease. Effective second-line treatment for these patients is of the most importance. We performed a phase II study with cisplatin and pirarubicin (each drug 50 mg/m2 i.v. every 28 days) in 17 patients with relapsed or persistent ovarian carcinoma. All patients had received platinum-containing primary chemotherapy. Overall survival from the time of diagnosis was 38.3 months (45.3 months in relapsed ovarian carcinoma and 28.3 months in ovarian carcinoma persisting after primary chemotherapy). Survival from entrance into the study was 13.0 months (14.2 months in relapsed disease and 11.2 months in refractory disease). Time to progression was 10.3 months. An objective response was observed in 4 patients and another 3 patients had stable disease. Major toxicity consisted of emesis (grade III/IV in 60/64 courses) and myelosuppression WHO grade III/IV in 15 courses. Neurotoxicity occurred in 3 patients and nephrotoxicity in 1 patient. Alopecia occurred in 12 patients. Tachycardia and other low-grade heart toxicities were observed after 5 courses. Dose reduction was necessary because of severe myelosuppression in 4 courses and because of nephrotoxicity in 1 course. Delay of subsequent chemotherapy courses for more than 7 days was necessary after 13 courses and was always due to myelosuppression. The dose-limiting toxicity of combination chemotherapy with cisplatin and pirarubicin is myelosuppression. Response and survival rates are superior in patients with relapsed disease compared to patients with resistant ovarian carcinoma.

Phase I and pharmacokinetics studies of prochlorperazine 2-h i.v. infusion as a doxorubicin-efflux blocker

In an earlier phase I study, we reported that the maximal tolerated dose (MTD) of prochlorperazine (PCZ) given as a 15-min i.v. infusion was 75 mg/m2. The highest peak plasma PCZ concentration achieved was 1100 ng/ml. The present study was conducted to determine if PCZ levels high enough to block doxorubicin (DOX) efflux in vitro could be achieved and sustained in vivo by increasing the duration of i.v. infusion from 15 min to 2 h. The treatment schedule consisted of i.v. prehydration with at least 500 ml normal saline (NS) and administration of a fixed standard dose of 60 mg/m2 DOX as an i.v. bolus over 15 min followed by i.v. doses of 75, 105, 135, or 180 mg/m2 PCZ in 250 ml NS over 2 h. The hematologic toxicities attributable to DOX were as expected and independent of the PCZ dose. Toxicities attributable to PCZ were sedation, dryness of mouth, anxiety, akathisia, hypotension, cramps, and confusion. The MTD of PCZ was 180 mg/m2. Large interpatient variation in peak PCZ plasma levels (91-3215 ng/ml) was seen, with the plasma half-life (t1/2 alpha) being approximately 57 min in patients given 135-180 mg/m2 PCZ. The volume of distribution (Vd), total clearance (ClT), and area under the curve (AUC) were 350.1 +/- 183.8 1/m2, 260.7 +/- 142.7 l m2 h-1 and 1539 +/- 922 ng ml h-1, respectively, in patients given 180 mg/m2 PCZ and the respective values for patients receiving 135 mg/m2 were 48.9 +/- 23.76 l/m2, 33.2 +/- 2.62 l m2 h-1, and 4117 +/- 302 ng ml h-1. High PCZ plasma levels (> 600 ng/ml) were sustained in all patients treated with 135 mg/m2 PCZ for up to 24 h. DOX plasma elimination was biphasic at 135 and 180 mg/m2 PCZ, and a > 10-ng/ml DOX plasma level was maintained for 24 h. Partial responses were seen in three of six patients with malignant mesothelioma, in two of ten patients with non-small-cell lung carcinoma, and in the single patient with hepatoma. Our data show that PCZ can be safely given as a 2-h infusion at 135 mg/m2 with clinically manageable toxicities. The antitumor activity of the combination of DOX and PCZ needs to be confirmed in phase II trials.

Prochlorperazine as a doxorubicin-efflux blocker: phase I clinical and pharmacokinetics studies

Doxorubicin (DOX) efflux in drug-resistant cells is blocked by phenothiazines such as trifluoperazine (TFP) and prochlorperazine (PCZ) in vitro. The present phase I study was conducted in 13 patients with advanced, incurable, nonhematologic tumors to determine whether PCZ plasma levels high enough to block DOX efflux could be achieved in vivo. The treatment schedule consisted of prehydration and i.v. administration of 15, 30, 50, and 75 mg/m2 PCZ followed by a standard dose of 60 mg/m2 DOX. The hematologic toxicities attributable to DOX were as expected and independent of the PCZ dose used. Toxicities attributable to PCZ were sedation, dryness of the mouth, cramps, chills, and restlessness. The maximal tolerated dose (MTD) of PCZ in this schedule was 75 mg/m2. Pharmacokinetic analysis indicated a large interpatient variation in peak plasma PCZ levels that ranged from 95 to 1100 ng/ml. The three plasma half-lives of PCZ were: t1/2 alpha (+/- SE), 20.9 +/- 5.3 min; t1/2 beta, 1.8 +/- 0.3 h; and t1/2 gamma, 21.9 +/- 5.3 h. The volume of distribution (Vd), total clearance (ClT), and area under the curve (AUC) for PCZ were 2254 +/- 886 l/m2, 60.2 +/- 13.5 l m-2 h-1, and 1624 +/- 686 ng ml-1 h, respectively. DOX retention in tumor cells retrieved from patients during the course of therapy indicated the appearance of cells with enhanced DOX retention. The combination of DOX and high-dose i.v. PCZ appeared to be safe, well tolerated, and active in non-small-cell lung carcinoma.

Phase II trial of 4'-0-tetrahydropyranyladriamycin (pirarubicin) in head and neck carcinoma

BACKGROUND

4'-0-tetrahydropyranyladriamycin (Pirarubicin, Meiji Seika (USA) Inc., New York, NY) may be less toxic than doxorubicin.

METHODS

A Phase II trial of Pirarubicin was done in 26 patients who had not previously had chemotherapy and who had measurable and incurable head and neck carcinoma. All patients received an intravenous bolus dose of 60 mg/m2 Pirarubicin in the first cycle without any prophylactic antiemetic. The cycles were repeated every 3 weeks. Based on tumor response, nadir counts, or complications of myelosuppression, the doses were escalated or de-escalated by 10 mg/m2, if necessary, in the second cycle to achieve mild leukopenia (3000-4000 leukocytes/microliters).

RESULTS

Leukopenia was mild, moderate (2000-2999 leukocytes/microliters), severe (1000-1999 leukocytes/microliters), and life threatening (less than 1000 leukocytes/microliters) in 13%, 31%, 27%, and 9% of the first two courses, respectively. The median interval to nadir leukopenia was 13 days (range, 7-21 days), with a median of 8 days (range, 5-13 days) to recover to normal. One patient with a leukocyte count of 800/microliters and an absolute granulocyte count (AGC) of 488/microliters died of sepsis 15 days after the first course. All patients had at least one course that resulted in leukopenia. One episode each of mild (100,000-150,000 platelets/microliters) and severe (25,000-49,999 platelets/microliters) thrombocytopenia occurred in the first two courses. Leukocyte, granulocyte, and platelet counts were not done routinely after the second cycle. Six patients who received four or more courses with cumulative doses of 310, 610, 340, 260, 660, and 550 mg/m2 had decrements of 0%, 1%, 7%, 10%, 12%, and 13%, respectively, in radionuclide left ventricular ejection fraction (LVEF). All other toxic effects were mild.

CONCLUSIONS

In the 24 patients with disease evaluable for response to Pirarubicin therapy, 1 had a complete response that lasted 5 months and 4 had a partial response of 2, 3, 6, and 8 months. The median survival time in patients with disease that responded to Pirarubicin therapy was 27 months; in patients with disease that did not respond to Pirarubicin therapy, the median survival time was 4 months, and in the total cohort, it was 5 months. Pirarubicin was well tolerated and was an active agent in head and neck squamous cell carcinoma.

Phase II clinical study of pirarubicin in hormone resistant prostate cancer

Twenty one patients with hormone resistant prostate cancer were entered in a phase II study of pirarubicin 70 mg/m2, as a single intravenous injection given at 21 day intervals. All patients had leukopenia (9 severe or life threatening) and 2 died of septicemia. Thrombocytopenia occurred in 5 patients (one life threatening) and anemia in 12 patients. One partial response of 3 months duration was documented. Pirarubicin 70 mg/m2 given intravenously at 21 day intervals causes severe hematological toxicity and has minimal therapeutic activity in patients with hormone resistant prostate cancer.

Comparative evaluation of pirarubicin and adriamycin in gynecologic cancer cell lines

Pirarubicin (PIRA) has been shown to have improved potency with less cardiac toxicity in several phase I and II clinical trials in Japan and Europe. Since Adriamycin (DXR) remains one of the most potent drugs in treatment of gynecologic cancers, this derivative has the potential to become an important chemotherapeutic agent. In this study, we compared the performance of these two drugs against a panel of 10 gynecologic cancer cell lines. The ATP chemosensitivity assays were used to determine dose-response curves. Flow cytometry was used to study cell kinetic response to both drugs. Using an IC50 value of 0.2 micrograms/ml as a cutoff for drug sensitivity, 4 cell lines, ECC1, HEC1B, BG1, and SKOV3, were considered resistant to DXR. By comparing IC50s, PIRA was 3.4 +/- 0.4 times more potent than DXR (P = 0.05). The other 6 cell lines, AN3, AE7, HEC1A, CAOV3, SKUT1B, and ME180, were considered sensitive to DXR. In this group of cell lines, PIRA was 1.6 +/- 0.3 times more potent than DXR (P = 0.5). Both PIRA and DXR elicited a spectrum of cell kinetics. By comparing the magnitude of G2 blocks at 0.1 micrograms/ml, PIRA was approximately 2-5 times more potent than DXR in SKUT1B, HEC1A, and BG1 cell lines. PIRA also displayed a reverse dose-response pattern of G2 block so that at high dose, cell cycle kinetics would mirror those of untreated controls. This observation supports the presence of a resistant tumor subpopulation and the concept of tumor heterogeneity.

A pharmacokinetic and pharmacodynamic study of the new anthracycline pirarubicin in breast cancer patients

We evaluated the pharmacokinetics of pirarubicin during 16 courses of therapy in 4 patients suffering from breast cancer who were treated with an association of pirarubicin (30-60 mg/m2 according to the hematologic tolerance to the previous course, the first course being given at a dose of 40 mg/m2) and continuous infusions of 5-fluorouracil (750 mg/m2 daily for 5 days). Pirarubicin's pharmacokinetics and metabolism were linear within this dose range; the metabolites identified were pirarubicinol, doxorubicin and doxorubicinol (AUC ratios of metabolite/pirarubicin were 0.6, 0.64 and 0.57 respectively). Pirarubicin's decay from plasma followed a two-compartmental pattern, showing half-lives of 15.6 min and 16.6 h; the total plasma clearance of the drug was 140 l/h-1/m-2, and the total volume of distribution was 2,830 l/m2. A relationship was observed between some pharmacokinetic parameters and the toxic effects of the drug: the percentage of survival of granulocytes was significantly correlated with the AUC values for doxorubicin and doxorubicinol, whereas that of platelets was significantly correlated with the AUC values for pirarubicin and pirarubicinol. This is the first study to demonstrate a pharmacokinetic/pharmacodynamic relationship for pirarubicin.