A pharmacokinetic study of high-dose continuous infusion cisplatin in children with solid tumors

A novel alternative method for long-term evaluation of male reproductive toxicity and its recovery using a pre-pubertal mouse testis organ culture system

Successful treatment of pediatric cancers often results in long-term health complications, including potential effects on fertility. Therefore, assessing the male reproductive toxicity of anti-cancer drug treatments and the potential for recovery is of paramount importance. However, in vivo evaluations are time-intensive and require large numbers of animals. To overcome these constraints, we utilized an innovative organ culture system that supports long-term spermatogenesis by placing the testis tissue between a base agarose gel and a polydimethylsiloxane ceiling, effectively mirroring the in vivo testicular environment. The present study aimed to determine the efficacy of this organ culture system for accurately assessing testicular toxicity induced by cisplatin, using acrosin-green fluorescent protein (GFP) transgenic neonatal mouse testes. The testis fragments were treated with different concentrations of cisplatin-containing medium for 24 h and incubated in fresh medium for up to 70 days. The changes in tissue volume and GFP fluorescence over time were evaluated to monitor the progression of spermatogenesis, in addition to the corresponding histopathology. Cisplatin treatment caused tissue volume shrinkage and reduced GFP fluorescence in a concentration-dependent manner. Recovery from testicular toxicity was also dependent on the concentration of cisplatin received. The results demonstrated that this novel in vitro system can be a faithful replacement for animal experiments to assess the testicular toxicity of anti-cancer drugs and their reversibility, providing a useful method for drug development.

Clinical pharmacology of cytotoxic drugs in neonates and infants: Providing evidence-based dosing guidance

Cancer in neonates and infants is a rare but challenging entity. Treatment is complicated by marked physiological changes during the first year of life, excess rates of toxicity, mortality, and late effects. Dose optimisation of chemotherapeutics may be an important step to improving outcomes. Body size-based dosing is used for most anticancer drugs used in infants. However, dose regimens are generally not evidence based, and dosing strategies are frequently inconsistent between tumour types and treatment protocols. In this review, we collate available pharmacological evidence supporting dosing regimens in infants for a wide range of cytotoxic drugs. A systematic review was conducted, and available data ranked by a level of evidence (1-5) and a grade of recommendation (A-D) provided on a consensus basis, with recommended dosing approaches indicated as appropriate. For 9 of 29 drugs (busulfan, carboplatin, cyclophosphamide, daunorubicin, etoposide, fludarabine, isotretinoin, melphalan and vincristine), grade A was scored, indicating sufficient pharmacological evidence to recommend a dosing algorithm for infants. For busulfan and carboplatin, sufficient data were available to recommend therapeutic drug monitoring in infants. For eight drugs (actinomycin D, blinatumomab, dinutuximab, doxorubicin, mercaptopurine, pegaspargase, thioguanine and topotecan), some pharmacological evidence was available to guide dosing (graded as B). For the remaining drugs, including commonly used agents such as cisplatin, cytarabine, ifosfamide, and methotrexate, pharmacological evidence for dosing in infants was limited or non-existent: grades C and D were scored for 10 and 2 drugs, respectively. The review provides clinically relevant evidence-based dosing guidance for cytotoxic drugs in neonates and infants.

Chemotherapy induced damage to spermatogonial stem cells in prepubertal mouse in vitro impairs long-term spermatogenesis

Chemotherapy can affect testis development of young boys with cancer, reducing the chances of fatherhood in adulthood. Studies using experimental models are needed to determine the damage caused by individual chemotherapy drugs in order to predict the risk of infertility and direct patients towards appropriate fertility preservation options. Here, we investigated the individual role of two drugs, cisplatin and doxorubicin, using an in vitro culture model of prepubertal (postnatal day 5) mouse testis that supports induction and maintenance of full spermatogenesis. Twenty-four hour exposure with either drug at clinically-relevant doses (0.25, 0.5 or 0.75 μg/mL for cisplatin, or 0.01, 0.03 or 0.05 μg/mL for doxorubicin), induced an acute significant loss of spermatogonial stem cells (SSCs; PLZF+), proliferating SSCs (PLZF+BrdU+), total germ cells (MVH+), and spermatocytes (SCP3+) one week after chemotherapy exposure. By the time of the first (Week 4) and second (Week 8) waves of spermatogenesis, there was no longer any effect on SSC or proliferating SSC numbers in drug-exposed testis compared to untreated tissue: however, the populations of total germ cells and spermatocytes were still lower in the higher-dose cisplatin treated groups, along with a reduced frequency of round and elongated spermatids in both cisplatin- and doxorubicin-treated testis fragments. Overall, this study details a direct impairment of germ cell development following acute chemotherapy-induced damage during the prepubertal phase, most likely due to an effect on SSCs, using an in vitro culture system that successfully recapitulates key events of mouse spermatogenesis.

Cisplatin and carboplatin pharmacokinetics in a pediatric patient with hepatoblastoma receiving peritoneal dialysis

Purpose

Cisplatin and carboplatin are frequently used drugs in the treatment of pediatric hepatoblastoma. Dosing guidelines for these drugs in children requiring peritoneal dialysis are lacking. Here, we describe the case of a 3-year-old boy with pre-existing end-stage renal disease on peritoneal dialysis, requiring treatment with cisplatin and carboplatin for hepatoblastoma.

Methods

Pharmacokinetic data were generated to support clinical dosing decisions, with the aim of adequate exposure and minimal toxicity. In the first chemotherapy cycle, 25% of the standard cisplatin dose and 75% of the carboplatin dose, calculated using the pediatric Calvert formula, were administered. Free platinum concentrations were determined in plasma ultrafiltrate and dialysate samples drawn after administration of cis- and carboplatin.

Results

Cisplatin was well tolerated and the observed AUC of cisplatin were 15.3 and 14.3 mg/L h in cycles 1 and 3, respectively. The calculated AUC of carboplatin in cycle 1 (9.8 mg/mL min) exceeded target AUC of 6.5 mg/mL min and toxicity was observed; therefore, the dose was reduced in cycles 2 and 3. The observed AUC in cycles 2 and 3 was 5.4 and 5.7 mg/mL min respectively. Platinum concentrations in the dialysate showed that 3–4% of the total dose of cisplatin and 10–12% of the total dose of carboplatin were excreted via peritoneal dialysis. Chemotherapy enabled extended hemihepatectomy and complete remission was achieved.

Conclusion

This report shows that it is feasible to measure AUCs for both drugs and to individualize the dose of these drugs according to the PK results and clinical parameters. Our advice for future cases would be to calculate the starting dose of carboplatin using the (pediatric) Calvert formula, assuming a dialytic clearance of zero, and to adjust the dose if required, based on therapeutic drug monitoring.

Comparative gonadotoxicity of the chemotherapy drugs cisplatin and carboplatin on prepubertal mouse gonads

The treatment of childhood cancer with chemotherapy drugs can result in infertility in adulthood. Newer generations of drugs are developed to replace parent drugs, with the potential benefits of less toxic side effects. For platinum alkylating-like drugs, in contrast to the parent compound cisplatin, the newer-generation drug carboplatin is reported to have reduced toxicity in some respects, despite being administered at 5-15 times higher than the cisplatin dose. Whether carboplatin is also less toxic than cisplatin to the reproductive system is unknown. Here we compare the gonadotoxic impact of cisplatin and carboplatin on female and male mouse prepubertal gonads. In vitro cultured CD1 mouse ovaries or testis fragments were exposed to either cisplatin or carboplatin for 24 h on Day 2 of culture and analysed by Day 6. A dose response for each drug was determined for the ovary (0.5, 1 & 5 μg/ml cisplatin and 1, 5 & 10 μg/ml carboplatin) and the testis (0.01, 0.05 & 0.1 μg/ml cisplatin and 0.1, 0.5 & 1 μg/ml carboplatin). For the ovary, unhealthy follicles were evident from 1 μg/ml cisplatin (73% unhealthy, P = 0.001) and 5 μg/ml carboplatin (84% unhealthy, P = 0.001), with a concomitant reduction in follicle number (P = 0.001). For the testis, the proliferating germ cell population was significantly reduced from 0.05 μg/ml cisplatin (73% reduction, P = 0.001) and 0.5 μg/ml carboplatin (75% reduction, P = 0.001), with no significant impact on the Sertoli cell population. Overall, results from this in vitro animal model study indicate that, at patient equivalent concentrations, carboplatin is no less gonadotoxic than cisplatin.

First determination of the levels of platinum group metals in Manta birostris (manta ray) caught along the Ghanaian coastline

Tissues from Manta birostris caught by fishermen from Dixcove in the western part of Ghana were analyzed for their Platinum, palladium and rhodium concentrations (PGM). The use of chondrichthyan fish has permitted the study of trace levels of Platinum group metals (PGMs) which have travelled very far into the sea. The analysis showed that Ghana's coastline is fairly polluted with these platinum group metals (PGMs). PGM concentration in manta ray recorded a range of (0.15-0.85) microg/g for Pt, (0.033-0.67) microg/g for Pd and (0.007-0.145) microg/g for Rh. Comparing these values to the UK dietary intake of 0.2 microg/day for Pt and Rh and 1.0 microg/day for Pd, its indicates that the values obtained from the analysis for Pt was above the required level. This is the first study to show the accumulation of PGM in chondrichthyan fish, although the sources of this pollution are not clear as manta birostris is migratory and therefore need to be investigated further. The presence of the PGM is very significant, since manta ray meat is consumed in Ghana. This may presents a health risk, due to a possible accumulation of PGMs in humans.

Cisplatin pharmacokinetics in a child receiving peritoneal dialysis

Cisplatin is a highly effective and frequently used drug in the chemotherapy of solid tumors in children, but there is currently no information to guide dosing in children requiring dialysis. Here, we present the case of a 2-year-old boy with end-stage renal disease managed with peritoneal dialysis and requiring cisplatin for a newly diagnosed hepatoblastoma. A pharmacokinetic study was performed to personalize the cisplatin dose with the goal of providing adequate cisplatin exposure and avoiding excessive exposure and toxicity. Accordingly, 25% of the standard cisplatin dose was infused intravenously over 4 h. Serial blood and peritoneal fluid samples were obtained, and free cisplatin levels were subjected to noncompartmental pharmacokinetic analysis. The disposition of free cisplatin was significantly altered as compared to that of normal children. Despite a 75% dose reduction, our patient showed a fourfold increase in free cisplatin exposure (AUC = 64.1 h mcg/mL) compared with the AUC observed in children with normal kidney (15 + or - 9 h mcg/mL) function. When a subsequent dose was decreased to 8.7% of the standard dose, the free cisplatin AUC measured 29.7 h mcg/mL and more closely approximated the exposure observed in children with normal kidney function.

The impact of vehicular fallout on the Pra estuary of Ghana (a case study of the impact of platinum group metals (PGMs) on the marine ecosystem)

It is increasingly being recognised and environmental measurements have demonstrated that Platinum (Pt) (and potentially Rhodium (Rh) and Palladium (Pd)) is released with the ageing of catalytic converters. Platinum is a particular concern as it has a known mutagenic and toxic effect, even at exceedingly low concentrations, in urban air (affecting human health) and urban water (affecting ecosystem health). In the context given above and given the still keen lack of reliable experimental data on the levels of Pd, Pt and Rh in water and sediment, this study determined the concentration of such elements in water and sediment of the Pra estuary in the Western Region of Ghana where it is estimated that more than two thousand cars pass over the bridge under which the river flows to join the sea each day. Elevated concentrations of platinum (Pt), palladium (Pd) and Rhodium (Rh) were found to be associated with water and soils from areas of high traffic densities (Beposo) suggesting that vehicles also contribute heavy metals (PGMs) to the environment. The result showed elevated levels of these metals in river bank, waterbed and in the water. There is therefore the tendency of possible accumulation of these metals in plant and animals along these areas.

Pharmacokinetic studies in children with cancer

We reviewed the current status of our knowledge of pharmacokinetics and pharmacodynamics of some anti-neoplastic drugs, used in the treatment of childhood cancer. Extrapolation of data from pharmacokinetic studies in adults to the paediatric population is often not feasible. Specific studies in children are needed. Of all reviewed anti-neoplastic drugs methotrexate appears to be most extensively studied. Methotrexate pharmacokinetics is correlated with toxicity and response to therapy, and it has been shown that individualized adaptive dosing of methotrexate is correlated with a better response to therapy without increasing toxicity in children with ALL and osteosarcoma. Of most of the other reviewed anti-neoplastic drugs it is demonstrated that pharmacokinetics is correlated with toxicity, and of some drugs a relationship of pharmacokinetics with response to therapy is demonstrated as well. In case of cytarabine, etoposide, and teniposide, individualized dosing also appears to be feasible. However, there is no evidence that this strategy improves response to therapy. Specifically data on pharmacokinetic and pharmacodynamic correlations and effect of pharmacokinetically guided, individualized dosing are important for the design of optimal cancer chemotherapy for individual patients. Unfortunately for a considerable number of anti-neoplastic drugs these specific data are lacking in children and future research is needed.

Hyperthermic isolated regional perfusion with CDDP for bone and soft-tissue sarcoma of the lower limb: pharmacokinetics, thermal dose, toxicity, and feasibility

The objectives of this study were to investigate the pharmacokinetics of cisplatin (CDDP) and the thermal dose, toxicity, and feasibility of hyperthermic isolated regional perfusion (HIRP) with CDDP for bone and soft-tissue sarcomas of the lower limb. A total of 43 patients were treated with HIRP using CDDP. The dose of CDDP administered was 62.9+/-11.8 mg/limb (20 mg/m(2) +20 approximately 30 mg). The mean highest CDDP concentration was 56.9 microg/ml as total platinum (tPt) and 49.0 microg/ml as free platinum (fPt). The tPt concentration remained higher than 10 microg/ml. The highest temperature within tumor was 42.3+/-1.4 degrees C on average. The complications of HIRP were grade II toxicity in 30 patients, grade III in 9, and grade IV in 4. The mean necrotic ratio in the resected specimen was 84.5%, and the effect was grade IV (no viable tumor cells) in 13 patients, grade III(>90% necrosis) in 12, grade II (50 to <90%) in 9, and grade I (<50%) in 4. We obtained favorable levels of platinum concentration of the perfusate using a lower CDDP dosage compared with previous studies of HIRP. Considering our results of the pharmacokinetics of CDDP and clinical efficacy, we propose a lower dosage of CDDP for HIRP in the treatment of osteosarcoma. Multimodality treatment of HIRP with preoperative chemotherapy and surgery is a relatively safe and reliable therapeutic option for patients with limb sarcomas, and our method offers excellent local control.

Platinum Compound-Related Ototoxicity in Children: Long-Term Follow-Up Reveals Continuous Worsening of Hearing Loss

OBJECTIVES

The purpose of this study was to evaluate the severity of hearing loss after cisplatin and/or carboplatin treatment in young children and to analyze its evolution and its relation to different therapy schedules.

METHODS

One hundred twenty patients treated in the Pediatrics Department at the Institut Gustave-Roussy from 1987 to 1997 for neuroblastoma, osteosarcoma, hepatoblastoma, or germ cell tumors were analyzed. Median age at diagnosis was 2.6 (range 0-17) years. Median follow-up was 7 (1-13) years. Chemotherapy regimens contained cisplatin and/or carboplatin. Three patients also received high-dose carboplatin. Cisplatin was administered at a dose of 200 mg/m/course in 72% of cases. The median cumulative dose was 400 mg/m for cisplatin and 1,600 mg/m for carboplatin. Hearing loss of grade 2 or above, according to Brock's grading scale, was revealed with pure tone audiometry and behavioral techniques.

RESULTS

Carboplatin alone was not ototoxic. Deterioration of hearing of grade 2 or above was observed in 37% of patients treated with cisplatin and 43% of patients treated with cisplatin plus carboplatin (P = NS). Fifteen percent of patients experienced grade 3 or 4 ototoxicity. Ototoxicity was most often observed after a total cisplatin dose of at least 400 mg/m. No improvement was observed with time; on the contrary, worsening or progression of hearing loss at lower frequencies was detected during follow-up. Only 5% of audiograms showed toxicity of at least grade 2 before the end of therapy; in contrast, this level was observed in 11% of early post-therapy evaluations and in 44% after more than 2 years of follow-up.

CONCLUSIONS

Children treated with cisplatin at cumulative doses approaching 400 mg/m require long-term surveillance to avoid overlooking hearing deficits. Carboplatin, at a standard dose, does not appear to be a significant risk factor for ototoxicity even in patients who have already been treated with cisplatin.

Clinical and cellular pharmacology in relation to solid tumours of childhood

Our understanding of the clinical and cellular pharmacology of drugs commonly used in the treatment of childhood cancer have increased greatly over the past two decades. However, with the exception of childhood acute lymphoblastic leukaemia (ALL), our current knowledge of factors such as inter-patient pharmacokinetic variability and cellular determinants of chemosensitivity has not been utilized in the design of integrated clinical studies. Recent pre-clinical and clinical evaluation of the topoisomerase I inhibitors topotecan and irinotecan has highlighted the potential importance of pharmacological factors in their effectiveness as cytotoxics. In this review, the clinical and cellular pharmacology of vincristine, actinomycin D, doxorubicin, cyclophosphamide, ifosfamide, cisplatin, carboplatin and etoposide will be discussed in relation to the major paediatric solid tumours. For each disease type, knowledge of the clinical and cellular pharmacology of a candidate drug will be related to pharmacodynamic responses such as response, toxicity and prognosis. For diseases such as Wilms' tumour, osteogenic sarcoma and Ewing's tumour, histological response to initial induction chemotherapy is of prognostic significance, and the depth of response is increasingly recognised as an important determinant of prognosis for high-risk neuroblastoma. For several of these tumour types, the dose-intensity of chemotherapy may be an important variable in determining prognosis. However the relationship between pharmacokinetic variability, cellular pharmacology and the major determinants of chemosensitivity to those drugs employed in first line therapy is unknown. The study of these relationships, by means of up front window studies in children who present with high-risk disease, may be as important as the introduction of new agents. Indeed, the optimisation of current therapies may be required to allow a fully informed selection of those children for whom novel therapies are truly needed. Funding and international collaboration at the clinical and scientific level would be required to achieve these aims.

A phase I study in paediatric patients to evaluate the safety and pharmacokinetics of SPI-77, a liposome encapsulated formulation of cisplatin

Pre-clinical studies indicate that cisplatin encapsulated in STEALTH((R))liposomes (SPI-77) retains anti-tumour activity, but has a much reduced toxicity, compared to native cisplatin. A phase I study was conducted to determine the toxicity and pharmacokinetics of SPI-77 administered to children with advanced cancer not amenable to other treatment. Paediatric patients were treated at doses ranging from 40 to 320 mg m(-2)by intravenous infusion every 4 weeks. Blood samples taken during, and up to 3 weeks after, administration and plasma and ultrafiltrate were prepared immediately. Urine was collected, when possible, for 3 days after administration. SPI-77 administration was well tolerated with the major toxicity being an infusion reaction which responded to modification of the initial infusion rate of SPI-77. Limited haematological toxicity and no nephrotoxicity were observed. No responses to treatment were seen during the course of this phase I study. Measurement of total plasma platinum showed that cisplatin was retained in the circulation with a half life of up to 134 h, with maximum plasma concentrations approximately 100-fold higher than those reported following comparable doses of cisplatin. Comparison of plasma and whole blood indicated that cisplatin was retained in the liposomes and there was no free platinum measurable in the ultrafiltrate. Urine recovery was less than 4% of the dose administered over 72 h. Results from this phase I study indicate that high doses of liposomal cisplatin can safely be given to patients, but further studies are required to address the issue of reformulation of liposomally bound cisplatin.

Chemosensitivity of solid tumor cells in vitro is related to activation of the CD95 system

We have identified the CD95 system as a key mediator of chemotherapy-induced apoptosis in leukemia and neuroblastoma cells. Here, we report that sensitivity of various solid tumor cell lines for drug-induced cell death corresponds to activation of the CD95 system. Upon drug treatment, strong induction of CD95 ligand (CD95-L) and caspase activity were found in chemosensitive tumor cells (Hodgkin, Ewing's sarcoma, colon carcinoma and small cell lung carcinoma) but not in tumor cells which responded poorly to drug treatment (breast carcinoma and renal cell carcinoma). Blockade of CD95 using F(ab')2 anti-CD95 antibody fragments markedly reduced drug-induced apoptosis, suggesting that drug-triggered apoptosis depended on CD95-L/receptor interaction. Moreover, drug treatment induced CD95 expression, thereby increasing sensitivity for CD95-induced apoptosis. Drug-induced apoptosis critically depended on activation of caspases (ICE/Ced-3-like proteases) since the broad-spectrum inhibitor of caspases zVAD-fmk strongly reduced drug-mediated apoptosis. The prototype substrate of caspases, poly(ADP-ribose) polymerase, was cleaved upon drug treatment, suggesting that CD95-L triggered autocrine/paracrine death via activation of caspases. Our data suggest that chemosensitivity of solid tumor cells depends on intact apoptosis pathways involving activation of the CD95 system and processing of caspases. Our findings may have important implications for new treatment approaches to increase sensitivity and to overcome resistance of solid tumors.

Cisplatin pharmacokinetics in children with cancer

Cisplatin is an important drug in the treatment of a number of paediatric cancers yet, despite widespread use, there are only very limited data on the pharmacokinetics of the drug in children. Cisplatin pharmacokinetics were studied in 21 patients following a 24 h infusion of 50-120 mg/m2 cisplatin. Total and free platinum (Pt) levels in plasma and Pt in urine, were measured by atomic absorption spectrophotometry. Pharmacokinetic parameters were determined by non-compartmental and compartmental analyses. There was 3-fold interpatient variability in free drug exposure (area under the plasma concentration versus time curve--AUC) for a given surface area-based dose of cisplatin. The mean (+/- SD) pharmacokinetic parameters for free Pt were: AUC 0.47 +/- 0.13 mg/ml.min/100 mg/m2, Vdss 12.5 +/- 2.7 l/m2, t1/2 39 +/- 9 min, Ke 0.019 +/- 0.006 min-1, Clrenal 62 ml/min/m2, Cltotal 233 +/- 455 ml/min/m2, Cpss 0.31 +/- 0.09 microgram/ml. The total free Pt clearance was 1.5-5.8-fold higher (3.4 +/- 1.0) than the glomerular filtration rate (GFR). The renal clearance of cisplatin was not related to GFR and cisplatin was subject to only limited urinary excretion (27% administered dose 0-48 h), indicating that there are other important pathways of clearance beside renal elimination. Patient and treatment heterogeneity precluded the investigation of pharmacokinetic-pharmacodynamic relationships; however, the degree of interpatient pharmacokinetic variability observed suggests that body surface area-based dosing of cisplatin in children is not satisfactory.

Radiotherapy with concomitant continuous cisplatin infusion for unresectable tumors of the upper aerodigestive tract: results of a phase I study

A phase I-II study was initiated in February 1991 of concomitant radiation and cisplatin (CDDP) in the treatment of unresectable head and neck squamous cell carcinomas (n = 12). The first patient was treated palliatively for a cervical recurrence of laryngeal cancer. The 11 other patients had locally advanced (stage IV) previously untreated carcinomas of the oropharynx (n = 9), hypopharynx (n = 1), or cervical node with unknown primary site (n = 1). Standard external radiation was carried out up to a total dose of 60 Gy/6 weeks (7 MeV electron beam) for the first patient and 72 Gy/8 weeks (Co60 beam) for the other 11 patients. CDDP was infused continuously during the entire radiation treatment, 5 days/week. The starting dose was 4 mg/m2/day and was escalated by increments of 1 mg/m2/day; dose-limiting toxicity was observed at 7 mg/m2/day. Neutropenia (grade 4, one patient; grade 3, three patients) and thrombocytopenia (grade 3, one patient; grade 2, one patient) were the limiting factors. Therefore, the recommended dose of CDDP is 6 mg/m2/day. All patients but one completed the scheduled radiation. For the entire group, mucositis was not more severe than that observed with radiotherapy alone. There was no nephro-, oto-, or neurotoxicity. A complete response was obtained in eight (66%) patients. Of these, four were free of disease 12-34 months after completion of treatment and one had a total glossectomy for a tongue necrosis. For the whole series, the mean overall survival was 16 months posttreatment. Pharmacokinetic analysis indicated the total cisplatin accumulation at the end of treatment to be 743-1551 ng/ml. Accumulation of ultrafilterable platin was noted in only one patient (137 ng/ml at the end of treatment).

High-dose ifosfamide, carboplatin, and etoposide pharmacokinetics: correlation of plasma drug levels with renal toxicity

An autologous bone marrow transplant regimen of ifosfamide, carboplatin, and etoposide (ICE) has been developed as treatment for certain malignancies. At maximum tolerated doses renal insufficiency precludes dose escalation. The objective was to examine whether measurement of plasma drug levels early during treatment would provide warning of renal failure. Nine patients received a 96-h continuous infusion of ifosfamide 16,000 mg/m2, carboplatin 1600 mg/m2, and etoposide 1200 mg/m2. Pharmacokinetics, including drug levels and plasma concentration-time curves, of ifosfamide, ultrafiltrable platinum (uPt) and etoposide were analyzed and correlated with renal function. One of the nine patients developed anuric renal failure requiring hemodialysis. By 17 h from the start of infusion, this patient showed substantially higher drug levels of ifosfamide (200 vs mean 217 microM) and uPt (19 vs mean 10 microM) than those patients with preserved renal function. The 95% confidence intervals suggested that a 16-22 h ifosfamide level > 153 microM and an uPt level > microM predict the development of significant renal dysfunction. Although drug levels were substantially higher at 56 h, the serum creatinine did not yet reflect kidney injury. This study suggests that high plasma ifosfamide and uPt levels, analyzed early in the course of a 96-h infusion of high-dose ICE, provide warning of severe and potentially fatal renal injury. Since ICE has substantial activity in a number of malignancies, but significant renal morbidity, real-time pharmacokinetic-guided dosing may reduce treatment-related toxicity.

Antiproliferative potential of cytostatic drugs on neuroblastoma cells in vitro

The role of single drugs in the treatment of neuroblastoma is poorly defined. We, therefore, tested neuroblastoma cell survival after a 72 h exposure to one of 19 cytostatic drugs by monolayer proliferation assay. 6 cell lines (IMR-5, Kelly, SK-N-SH, GI-CA-N, CHP-100, CHP-134) were selected on the basis of MYCN amplification and PGY1 overexpression. ED50 drug concentrations were related to plasma levels achievable in patients during chemotherapy. More effective substances were mitoxantrone, doxorubicin, hydroxyurea, bleomycin, dactinomycin, cisplatinum, thiotepa, melphalan, carboplatinum, etoposide, vincristine, cytarabine, 6-thioguanine, cyclophosphamide, ifosfamide and zilascorb. Parental drugs (cyclophosphamide, cisplatinum) appeared more cytotoxic on a molar basis than derived drugs (ifosfamide, carboplatinum). Less effective drugs included 5-fluorouracil, 6-mercaptopurine, CCNU and procarbazine. Fractional application of a given dose was more efficient than a single dose of cyclophosphamide, ifosfamide and cisplatinum. The tested neuroblastoma cell lines showed distinct sensitivities to cytostatic drugs. Cell lines with MYCN amplification appeared more sensitive than PGY1 overexpressing cells. In conclusion, comparative in vitro testing of cytostatic drugs may provide a rationale for their clinical evaluation. Investigation of drug combinations and application of the monolayer proliferation assay to tumour biopsy material for preclinical chemosensitivity testing are clearly warranted.

Determination of platinum in plasma of patients affected by inoperable lung carcinoma treated with radiotherapy and concurrent low-dose continuous infusion of cis-dichlorodiammine platinum(II)

Platinum microquantities were determined in plasma of patients affected by lung carcinoma during treatment with radiotherapy (RT) and concurrent low-dose continuous infusion of cis-dichlorodiammineplatinum(II) (CDDP). RT was given at 50 Gy in continuous course; CDDP was continuously infused at 4 mg/m2 daily for 100 h/week for 5 weeks, and the infusions were separated by 68 h of rest. The percentage of free drug versus total drug in plasma was about 3%. It did not vary with therapy duration and was not significantly different from that found in 5-day continuous infusions at much higher daily doses. Nevertheless, maximal values of free Pt in plasma were very low and agreed with the low level of CDDP toxicity encountered on the present administration schedule.

Long-term pharmacokinetic behavior of platinum after cisplatin administration

PURPOSE

The platinum concentration in plasma was studied in 19 patients treated by 3 or 4 successive courses of chemotherapy including cisplatin for head and neck cancers.

METHODS

Cisplatin was given i.v. daily at 25 mg/m2 by 1-h infusions for 4 days every 3 weeks. Total and ultrafiltrable platinum were measured in plasma using an inductively coupled plasma mass spectrometry (ICPMS) technique.

RESULTS

A progressive accumulation of total platinum in plasma was observed with consecutive infusions. The mean (+/- SD) total plasma platinum level detected at the end of cisplatin infusion was 1134 +/- 234, 1407 +/- 268, and 1618 +/- 282 micrograms/l at the end of the first, second, and third courses, respectively. The minimal platinum concentration measured before the second and third courses also increased to 221 +/- 59 and 309 +/- 76 micrograms/l, respectively. The steady state was not reached before the third course. However, differences in the evolution of platinum plasma levels were found among the 19 patients. In 14 patients the pharmacokinetics of platinum was characterized by low initial levels, a progressive accumulation, and a long terminal half-life with a very late steady state. In 5 patients, the pharmacokinetic behavior of platinum was different: platinum levels were directly high, without progressive accumulation, the steady state being reached as early as the first course. Significant levels of ultrafiltrable platinum were found throughout the treatment, even during the intervals between courses with this very sensitive analytical method. A close equilibrium between ultrafiltrable and total platinum (ratio, 6%) persisted for as long as 3 weeks after cisplatin administration.

DISCUSSION

These results underline the importance of individual differences in platinum metabolism. The relationship between total and ultrafiltrable platinum are discussed.

Protracted drug infusions in cancer treatment: an appraisal of 5-fluorouracil, doxorubicin, and platinums

The feasibility to deliver chemotherapeutic agents by protracted i.v. infusion has greatly increased in the recent past. Indwelling ports, longer lasting central venous catheters requiring less than daily maintenance 'flushing', surgical expertise in placement, use in analgesia and nutrition, and 'smart' pump technology have all contributed to their increasing popularity. Justification for use of infusions in cancer chemotherapy has been slow in appearing with few studies proceeding to the comparative stage. This review will focus on three drugs in common use in cancer treatment, with the purpose of appraising the role of such infusions in cancer therapeutics and of deriving some lessons that might be applicable to other drugs or to drug development in general. For fluorouracil and doxorubicin the rationale and clinical findings favoring further development of infusion regimens is particularly strong. In the case of platinum compounds, some toxicologic advantages have emerged, but other measures designed to protect against the toxicities of cisplatin compete with infusion regimens in this regard. The therapeutic potential for this form of drug delivery, therefore, appears still confined to a subset of patients. Stronger rationales for the use of protracted infusions may be forthcoming from pharmacodynamic findings as in the case of etoposide, combined modality therapy with radiation for FU and cisplatin, biochemical modulation for FU, and reversal of multidrug resistance and its modulation for doxorubicin. While awaiting research into these areas of clinical and pre-clinical investigations, the role of infusion appears most evident in the cardiotoxicity protection of anthracyclines, and in further efficacy exploration (through dose or modulation) of FU. Both mechanistic and pharmacologic considerations could also provide additional stimulus for development of new formulations such as long circulating liposomes, and drugs more suitable for oral administration.

EPIC: an effective low toxicity regimen for relapsing lymphoma

We have treated 40 patients was relapsed or resistant lymphoma with the combination of Etoposide, Prednisolone, Ifosfamide and Cisplatin (EPIC). Complete response was obtained in 11 patients (28%) with an overall response of 58%. The presence of bulky disease (P < 0.005), elevated LDH serum levels (P < 0.005), response to prior chemotherapy (P < 0.01) and B symptoms (P < 0.005) were significantly associated with response. However on multivariate analysis only the presence of bulky disease and of B symptoms were independent adverse factors for response and for survival. The regimen was well tolerated with myelosuppression being the most common toxicity. Leucopenia < or 1,000 microliters-1 and thrombocytopenia < or = 25,000 microliters-1 developed in 27% and 4% of cycles respectively. There were no treatment related deaths. The EPIC regimen has equivalent activity to other reported cisplatin based regimens used in the treatment of recurrent lymphoma, but is associated with lower treatment related morbidity and mortality.

Pilot study of a rapid etoposide-cisplatin regimen in paediatric soft tissue sarcomas

10 patients with refractory or relapsed soft tissue sarcoma were treated with weekly etoposide (150 mg/m2 on days 1, 2 and 3) and cisplatin (60 mg/m2 on day 2). Toxicity was mainly myelosuppression which resulted in deviation from planned weekly chemotherapy scheduling. With this rapid dose-delivery schedule the tolerated median dose intensities were 161 mg/m2 per week for etoposide and 49 mg/m2 per week for cisplatin. In 9 evaluable patients there were 7 responses, 2 complete and 5 partial, giving a response rate of 78% (confidence interval 51-100%). The combination of etoposide and cisplatin in this schedule produced a higher response rate than reported with previous schedules and is worthy of further evaluation.

Effects of prolonged exposure to cisplatin on cytotoxicity and intracellular drug concentration

The present study was designed to analyse the cytotoxic effect of cisplatin in vitro as a function of various exposure times (up to 120 h), keeping constant the parameter C x T (product of the drug concentration per time). Intracellular drug concentrations were measured in parallel following analysis of cisplatin influx and efflux characteristics. A head and neck cancer cell line was selected to represent the spectrum of cisplatin antitumour activity. The IC50 values (micrograms/ml) for 1, 2, 11 and 121 h were, respectively 4.51, 2.73, 0.27 and 0.151. Reduction of the IC50 was clearly not linearly related to prolongation of the cisplatin exposure time. The kinetics of cisplatin incorporation into CAL 27 cells was investigated as a function of different cisplatin concentrations. A plateau was reached after 16 h of contact. For the extracellular cisplatin concentrations of 1, 2.5, 5 and 10 micrograms/ml, the average intracellular Pt concentrations at the plateau were, respectively (ng/10(6) cells): [mean (S.D.)] 12.8 (0.98), 31.11 (5.12), 71.38 (6.03) and 136.7 (16.5). Intracellular Pt concentrations were linearly related to the extracellular drug concentration (r = 0.99). The drug left the cells following a two-slope kinetics pattern with an alpha half-life of 1.29 h and a beta half-life of 94.4 h. The cytotoxic effect for a given C x T clearly differed for the different cisplatin exposure times. The longest exposure time (121 h) gave the least pronounced cytotoxicity. The intracellular Pt concentrations were linearly related to the C x T values. Cisplatin levels were much lower after the 121 h exposure. These data may prove valuable in establishing a rationale which can aid in selection of optimal modes of clinical cisplatin administration.

Seizures and cortical dysfunction following high-dose cisplatin administration in children

Four of eight children with advanced neuroblastoma treated with a rapid delivery high dose intensity cisplatin based regimen developed acute neurological toxicity. Three had seizures and one developed transient blindness. In the absence of other causes it seems probable that high dose cisplatin (200 mg/m2) as a continuous infusion over five days followed 10 days later by 80 mg/m2 infused over 48 hours was responsible. Other risk factors included an associated deterioration in renal function and neutropenia related fever.

Effectiveness and toxicity of cisplatin and doxorubicin (PLADO) in childhood hepatoblastoma and hepatocellular carcinoma: a SIOP pilot study

Sixteen children, aged 16 days to 13 years with hepatoblastoma (HB) (13 patients) or hepatocellular carcinoma (HCC) (3 patients), were given a total of 89 courses of cisplatin and doxorubicin (PLADO) as IV continuous infusion. All tumors were confined to the liver except for 1 hepatoblastoma patient with pulmonary metastases at presentation. Tumor response to PLADO was evaluable in 10 children (8 HB, 2 HCC) treated with preoperative chemotherapy and in another 2 HB patients treated when they developed pulmonary metastases after initial treatment with surgery alone. There were 2 complete responses (2 HB with pulmonary recurrences), 7 very good partial responses (6 HB and 1 HCC), 2 partial responses (1 HB, 1 HCC), and 1 stable disease (HB). The last patient underwent orthotopic liver transplantation whereas all the other patients had their tumor completely excised at delayed surgery. Documented toxicity was BM depression (16 patients), infection (11), vomiting (11), mucositis (3), hearing loss (1), and cardiotoxicity (1). These data indicate that PLADO in continuous infusion is effective in the treatment of malignant epithelial liver tumors with acceptable toxicity.

Pharmacokinetics of cisplatin given at a daily low dose as a radiosensitiser

A total of 25 patients with inoperable cervical cancer were treated by daily radiotherapy (2 Gy); sensitisation was obtained by administration of 5 mg cisplatin 30 min before each irradiation session. The total cumulative dose of cisplatin varied between 50 and 150 mg. A complete kinetic profile (0-24 h) of platinum (Pt) was established after the first dose and at the end of treatment for 22 patients. Pt was quantified by atomic absorption spectrophotometry using Zeeman-effect background correction for trace analysis. The total Pt AUC0-24h increased from 1.53 +/- 0.77 to 7 +/- 3.55 micrograms.h.ml-1 between the start and the end of treatment (P less than 0.001). Ultrafilterable Pt (Pt UF) rose from 0.079 +/- 0.038 to 0.138 +/- 0.095 microgram.h.ml-1 (P less than 0.01). Elimination half-lives were unchanged for total Pt but rose for Pt UF; these kinetic modifications in Pt UF did not correlate with any significant change in individual serum creatinine levels. No clear correlation was found between the cumulative cisplatin dose and tumor levels measured in 13 patients, and the tumor cisplatin dose did not correlate with response to treatment. Patients with hematological toxicity were characterised by an increase in their residual Pt UF level during treatment. Overall, our findings strengthen the notion of Pt UF kinetic variability during repeated treatment.

Studies on age-dependent plasma platinum pharmacokinetics and ototoxicity of cisplatin

The age-related difference of cisplatin (CDDP) pharmacokinetics and ototoxicity were studied in 6 children with solid tumors who received CDDP infusion. CDDP was administered intravenously for 6 hours at a dosage of 30-120 mg/m2 and plasma-free platinum concentrations were determined by atomic absorption spectrophotometry. Plasma-free platinum concentrations ranged from 1.0 to 2.1 micrograms/ml at the end of infusions and declined rapidly with T1/2 of 0.6-1.5 hours. Pharmacokinetic parameters of plasma-free platinum were analyzed in 13 CDDP infusions by the one-compartment open model method. Parameters (Ke, Cl, T1/2 and Vd) of free platinum pharmacokinetics were 0.66 hr-1, 7.71l/hr, 1.35 hr and 15.71l in the younger group (age: 1.7-6.5 years old) and 1.44 hr-1, 11.41l/hr, 0.61 hr and 8.99l in the older group (age: 12.2-15.7 years old), respectively. Up to 600 mg/m2 of the cumulative dosage of CDDP caused minimal ototoxicity in the older group; however, in the younger group, hearing loss at a high frequency zone (6000 and 8000 Hz) began to appear at a cumulative dosage of 200 mg/m2 and progressed to middle zone (3000 Hz) when dosages surpassed 400 mg/m2. These data indicate that the pharmacokinetic difference in age possesses a large distribution volume (Vd) and that slower elimination of the drug in a younger age group is an important factor for age-dependent ototoxicity.