The influence of information on drug resistance on protocol design

Targeted radionuclide therapy

Targeted radiotherapy is an evolving and promising modality of cancer treatment. The killing of cancer cells is achieved with the use of biological vectors and appropriate radionuclides. Among the many advantages of this approach are its selectiveness in delivering the radiation to the target, relatively less severe and infrequent side effects, and the possibility of assessing the uptake by the tumor prior to the therapy. Several different radiopharmaceuticals are currently being used by various administration routes and targeting mechanisms. This article aims to briefly review the current status of targeted radiotherapy as well as to outline the advantages and disadvantages of radionuclides used for this purpose.

Evaluation of oxaliplatin dose intensity in bimonthly leucovorin and 48-hour 5-fluorouracil continuous infusion regimens (FOLFOX) in pretreated metastatic colorectal cancer. Oncology Multidisciplinary Research Group (GERCOR)

BACKGROUND

Studies of bimonthly 48-hour regimens of high-dose leucovorin (LV) (FOLinic acid), 5-fluorouracil (5-FU) by continuous infusion combined with OXaliplatin (FOLFOX) in pretreated patients with metastatic colorectal cancer suggest that oxaliplatin dose intensity is an important prognostic factor for response rate and progression-free survival (PFS). To help define the optimal dose schedule for oxaliplatin in pretreated metastatic colorectal cancer, we retrospectively analyzed data from three phase II studies using different FOLFOX regimens (FOLFOX2, 3 and 6).

PATIENTS AND METHODS

Data on 126/161 patients were analyzed. FOLFOX2 included oxaliplatin 100 mg/m2; FOLFOX3, 85 mg/m2; and FOLFOX6, 100 mg/m2 (added to a simplified LV-5-FU regimen), all as two-hour infusions. A total of 47 patients received low dose intensity oxaliplatin (LDI: < or = 85 mg/m2/2 weeks) and 79 patients high dose intensity oxaliplatin (HDI: > 85 mg/m2/2 weeks).

RESULTS

Objective responses occurred in 31 (39%) HDI patients and 9 (19%) LDI patients (P = 0.03). Median PFS was 28 weeks, with 52% of HDI patients progression free at 6 months, and 26 weeks with 36% of LDI patients progression free at six months (P = 0.02). Increased oxaliplatin dose intensity was not associated with increased neurotoxicity or other toxicities. FOLFOX are among the most effective regimens for treating LV-5-FU-resistant metastatic colorectal cancer.

CONCLUSIONS

This study shows that oxaliplatin dose intensification significantly improves response rate and PFS in pretreated metastatic disease without increasing severe toxicity.

A phase I dose escalation study of multicyclic, dose-intensive chemotherapy with peripheral blood stem cell support for small cell lung cancer

A phase I dose-escalation study of multicyclic, ifosfamide, carboplatin, and etoposide (ICE) with sequential reinfusion of peripheral blood stem cells (PBSCs) was conducted to determine the maximum-tolerated dose (MTD) of ICE. Twenty-four patients with SCLC (LD: 6, ED: 18) were treated with ifosfamide (3000-9000 mg/m2, 24-h infusion), carboplatin (300-400 mg/m2), and etoposide (300 mg/m2) followed by subcutaneous filgrastim (75 microg/day) from day 4 to the day of PBSC collection. PBSC were harvested when the WBC count reached >/=5 x 109/l. The leukapheresis product was cryopreserved and reinfused on day 4 of the next cycle, which was started 48 h after the last PBSC collection. The ifosfamide dose was escalated as follows: 3000 mg/m2 (level 1), 5000 mg/m2 (level 2), 7000 mg/m2 (level 3), 9000 mg/m2 (level 4). Patients with LD were treated with concurrent radiotherapy at 1.5 Gy twice daily for the initial 3 weeks to a total dose of 45 Gy and MTD, defined separately. Patients were evaluated for hematologic and non-hematologic toxicity, actual dose intensities, as well as response to therapy. The maximum-tolerated dose (MTD) was defined as the dose level at which more than 5 days of grade 4 myelo- suppression or non-hematologic toxicity greater than grade 3 developed in two thirds of the patients. For ED cases, MTD was level 4 and the recommended dose of ifosfamide was 7000 mg/m2. For LD cases, the recommended dose of ifosfamide was 5000 mg/m2. The dose limiting toxicity of multicyclic ICE was hemato- logic toxicity and CNS toxicity which manifested as ataxia. Tumor responses were seen in all patients, with 14 patients showing a complete response. The actual total dose-intensity at the recommended dose level was 2.2 and 1.74, for ED and LD, respectively, compared with previously reported ICE regimens. PBSC support for dose-intensive ICE regimen permitted dose escalation of ifosfamide with a mean interval of 16-17 days. We conclude that this regimen is well tolerated, with acceptable hematological and non-hematological toxicity. Bone Marrow Transplantation (2000) 25, 5-11.

Ventricular arrhythmia and torsade de pointe: dose limiting toxicities of the MDR-modulator S9788 in a phase I trial

BACKGROUND

S9788 is a triazineaminopiperidine derivative capable of reversing multidrug resistance (MDR) in vitro. In preclinical models S9788 was several fold more potent MDR inhibitor than verapamil or cyclosporine. At P-glycoprotein (Pgp) blocking concentrations, S9788 appeared to have only very little toxicity.

PATIENTS AND METHODS

In a two step phase I trial we treated 39 patients with refractory cancer with S9788 and bolus doxorubicin. The steps differed mainly in the S9788 infusion duration; in the first part 23 patients received the MDR-reversing drug S9788 over 30 minutes, in the second step of the study 16 patients were administered S9788 over 150 minutes. The doses of S9788 were escalated in cohorts of three patients up to a dose level (DL) of 96 mg/m2 on the 30 minutes infusion, and to 144 mg/m2 on the 150 minutes infusion. The pharmacokinetics of S9788 were determined.

RESULTS

With the 30-minute infusion schedule symptomatic cardiac arrhythmia were found to be dose limiting. In all patients at the highest DL transient cardiac repolarization prolongation with a long QT-interval on ECG was demonstrated. With the 150-minute administration schedule, S9788 could be escalated up to 144 mg/m2 without subjective toxicity. However, transient QT prolongation was present in all patients. A third degree AV-block and a QT increase of about 40% occurred at the highest DL. Asymptomatic torsade de pointe (DL 96 mg/m2) was demonstrated on Holter recording in one patient. Theses repolarization disturbances with QT increase were considered dose limiting toxicity and the trial was closed. No arrhythmia related death was noted. Pharmacokinetics were similar with both infusion schedules with a mean alpha half life of 11.3 and 13.2 minutes, for the 30-minute and 150-minute infusion, and a terminal half life of 13.5 and 15 hours, respectively. QTc prolongation duration appeared to be dose-dependent.

CONCLUSIONS

With the tested infusion schedules, cardiac toxicity, in particular AV-blocks and QT prolongation, leading to ventricular arrhythmia and torsade de pointe, are the dose limiting toxicities of S9788. Our experience together with the observation of asymptomatic torsade de pointe in two other phase 1 trials of S9788 infused over six hours precluded the further clinical development of S9788.

Modern treatment of malignant lymphomas: a multidisciplinary approach? The Kaplan Memorial Lecture

The aim of this review is to examine critically, in Hodgkin's disease and in non-Hodgkin's lymphomas, (a) whether combined modality treatment is superior to optimal radiotherapy or chemotherapy alone in most stages of the disease; (b) whether its indications could be further expanded by the use of new drug regimens and newer radiation techniques that can now substantially reduce the risk of long-term iatrogenic morbidity; and (c) whether it may become a necessary approach in the future because staging laparotomy and even lymphangiography are progressively falling into disuse. In conclusion, for the next decade or so, I do not foresee a departure from complex treatment programs. Although fewer patients are being referred to major research centers, the treatment of malignant lymphomas is not ready as yet to be relegated to the care of the single physician in a private office or local hospital.

Age does not influence taxol dose intensity in recurrent carcinoma of the ovary

BACKGROUND

In the treatment of advanced-stage ovarian cancer, it is common practice to treat elderly patients in a less aggressive fashion than young patients. This approach is based on the notion that age is associated with poor patient tolerance to aggressive chemotherapy. Relatively little data exist to support this contention. The most exciting new chemotherapy agent to be developed in the last 10 years is taxol, a diterpeniod derivative of the Northwestern yew Taxus brevifolia.

METHODS

The ability to administer dose-intensive taxol to adult patients with recurrent ovarian cancer was assessed retrospectively, and the question was asked whether the administered dose intensity of taxol was unfavorably influenced by age. Forty-eight patients with recurrent ovarian carcinoma received taxol at an initial dose of 250 mg/m2 every 3 weeks. Age in this cohort ranged from 26 to 74 years, with a median of 55. Twenty-nine percent (14 of 48) of the patients treated were 61 years of age or greater. Criteria for administration of taxol included a creatinine clearance of > 45 ml/minute, minimal abnormalities in liver function tests, good performance status, and the absence of substantial comorbid disease.

RESULTS

Elderly patients in this cohort (age > 60 years) did not differ from younger patients with respect to administered dose intensity, number of cycles of therapy administered, or the occurrence of serious or mild toxicities.

Doxorubicin sensitivity pattern in a panel of small-cell lung-cancer cell lines: correlation to etoposide and vincristine sensitivity and inverse correlation to carmustine sensitivity

The aim of our investigations is to evaluate whether the sensitivity patterns of small-cell lung-cancer (SCLC) cell lines in vitro can be used in evaluating new drugs and in selecting drugs for the optimization of combination therapy. In our attempts to obtain a panel of cell lines demonstrating differential patterns in sensitivity, we have developed three SCLC lines exhibiting different types of multidrug resistance (MDR). In the present investigations we compared the sensitivity patterns shown by five wild-type SCLC lines and three MDR lines in response to six different types of drugs: doxorubicin, cytarabine, carmustine, cisplatin, vincristine, and etoposide. In the wild-type SCLC cell lines, the range of variation in sensitivity to all drugs was within a factor of 10. Cell lines showing low sensitivity to doxorubicin also exhibited low sensitivity to etoposide and vincristine, and vice versa. In contrast, the pattern of sensitivity to carmustine was almost the opposite of that to doxorubicin. A tendency to an inverse relationship between doxorubicin and carmustine sensitivity was also observed when doxorubicin sensitivity was reduced in near stationary cells and in cells exposed to the metabolic inhibitor 2-deoxy-D-glucose. In agreement with the pattern observed for the wild-type lines, all of the MDR sublines demonstrated collateral sensitivity to carmustine. As to cytarabine, the wild-type lines expressed a sensitivity pattern similar to that shown in response to doxorubicin. Interestingly, the opposite pattern was found in the MDR lines, as all three demonstrated cytarabine hypersensitivity. The combination of alkylating agents and "MDR" drugs are of proven clinical benefit in the treatment of solid tumors, as is the combination of anthracycline and cytarabine in acute myeloid leukemia. The experimentally derived sensitivity data on cytarabine, alkylating agents, and MDR drugs (i.e., etoposide, doxorubicin, vincristine) thus resemble the clinical experience with these drugs, and we conclude that the use of a clonogenic assay on the described panel of SCLC cell lines can give valuable information for the selection of agents for combination therapy.

Metabolic response of AH13r rat tumours to cyclophosphamide as monitored by pO2 and pH semi-microelectrodes

The composition of the microenvironment has an important influence on the cellular response to cytotoxic agents. Using pH and pO2 semi-microelectrodes, we have monitored metabolic changes in AH13r rat tumours as a function of time after subcurative chemotherapy. Prior to therapy, tumours contained large areas considered hypoxic (mean pO2 approximately 4 mmHg) and are characterised by a marked accumulation of acidic metabolites (mean pH 6.65). Administration of cyclophosphamide (40 mg/kg body weight) resulted in tumour regression to 15% of pretreatment volumes and a growth delay of 12 days. Concomitant with volume reduction, tumours became reoxygenated (mean pO2 approximately 7 mmHg), with maximum values being reached within 2-4 days, paralleled by a shift of pH to more alkaline values (0.17 U on average). These changes coincided with the development of subtotal necrosis. During early tumour regrowth, the pH and pO2 histograms returned to control values. These data corroborate and extend the results of previous studies in which noninvasive techniques had been applied for the monitoring of treatment-induced metabolic changes in malignant tumours in vivo. In addition, these results support the notion that the effectiveness of anticancer therapy might be improved by selecting and scheduling therapeutic agents in consideration of physiological changes caused by preceding courses of treatment.