A Phase II study of paclitaxel by 24-hour infusion and ifosfamide in anthracycline-resistant metastatic breast carcinoma

Relevant pharmacological interactions between alkylating agents and antiepileptic drugs: Preclinical and clinical data

Seizures are relatively common in cancer patients, and co-administration of chemotherapeutic and antiepileptic drugs (AEDs) is highly probable and necessary in many cases. Nonetheless, clinically relevant interactions between chemotherapeutic drugs and AEDs are rarely summarized and pharmacologically described. These interactions can cause insufficient tumor and seizure control or lead to unforeseen toxicity. This review focused on pharmacokinetic and pharmacodynamic interactions between alkylating agents and AEDs, helping readers to make a rational choice of treatment optimization, and thus improving patients' quality of life. As an example, phenobarbital, phenytoin, and carbamazepine, by increasing the hepatic metabolism of cyclophosphamide, ifosfamide and busulfan, yield smaller peak concentrations and a reduced area under the plasma concentration-time curve (AUC) of the prodrugs; alongside, the maximum concentration and AUC of their active products were increased with the possible onset of severe adverse drug reactions. On the other side, valproic acid, acting as histone deacetylase inhibitor, showed synergistic effects with temozolomide when tested in glioblastoma. The present review is aimed at providing evidence that may offer useful suggestions for rational pharmacological strategies in patients with seizures symptoms undertaking alkylating agents. Firstly, clinicians should avoid the use of enzyme-inducing AEDs in combination with alkylating agents and prefer the use of AEDs, such as levetiracetam, that have a low or no impact on hepatic metabolism. Secondly, a careful therapeutic drug monitoring of both alkylating agents and AEDs (and their active metabolites) is necessary to maintain therapeutic ranges and to avoid serious adverse reactions.

Chemotherapy for Late-Stage Cancer Patients: Meta-Analysis of Complete Response Rates

Complete response (CR) rates reported for cytotoxic chemotherapy for late-stage cancer patients are generally low, with few exceptions, regardless of the solid cancer type or drug regimen. We investigated CR rates reported in the literature for clinical trials using chemotherapy alone, across a wide range of tumour types and chemotherapeutic regimens, to determine an overall CR rate for late-stage cancers. A total of 141 reports were located using the PubMed database. A meta-analysis was performed of reported CR from 68 chemotherapy trials (total 2732 patients) using standard agents across late-stage solid cancers—a binomial model with random effects was adopted. Mean CR rates were compared for different cancer types, and for chemotherapeutic agents with different mechanisms of action, using a logistic regression. Our results showed that the CR rates for chemotherapy treatment of late-stage cancer were generally low at 7.4%, regardless of the cancer type or drug regimen used. We found no evidence that CR rates differed between different chemotherapy drug types, but amongst different cancer types small CR differences were evident, although none exceeded a mean CR rate of 11%. This remarkable concordance of CR rates regardless of cancer or therapy type remains currently unexplained, and motivates further investigation.

Paclitaxel combined with ifosfamide in anthracycline- and docetaxel-pretreated metastatic breast cancer: activity independence of prior docetaxel resistance

BACKGROUND

We evaluated the efficacy and tolerability of combined paclitaxel and ifosfamide in anthracycline- and docetaxel-pretreated metastatic breast cancer (MBC).

METHODS

Patients received paclitaxel (175 mg/m(2) i.v. in a 3-h infusion) on day 1 and ifosfamide (1.5 g/m(2) i.v. in a 15-min infusion) on days 1-3, every 3 weeks for a maximum of nine cycles. The tumor response was assessed every two cycles.

RESULTS

We enrolled 34 patients with a median age of 50 years. Thirty patients had visceral metastases. Anthracycline- and docetaxel-based chemotherapy had previously been administered to 18/13 and 13/21 patients, respectively, in (neo)adjuvant/metastatic settings. Three patients had not previously received anthracycline due to abnormal cardiac functions. A total of 174 cycles of chemotherapy were delivered with a median of six cycles. The response rate under the intent-to-treat analysis was 23.5% (all partial responses) with a median response duration of 14 months. The disease control rate was 70.6%. The median progression-free and overall survival were 5.9 and 8.5 months, respectively. There was no apparent relationship between activity and prior docetaxel resistance. The incidence of grade III/IV neutropenia was 46.6% (81 of 174 cycles) with febrile neutropenia of only 1.7%. Major grade III/IV non-hematological toxicities included peripheral neuropathy (6 of 34 patients) and infection (4 of 34 patients). There were no treatment-related deaths.

CONCLUSION

Paclitaxel combined with ifosfamide was effective and tolerable in anthracycline-/docetaxel-pretreated MBC. Overcoming docetaxel resistance by using paclitaxel in combination with ifosfamide needs to be addressed through further investigation.

Metabolism and transport of oxazaphosphorines and the clinical implications

The oxazaphosphorines including cyclophosphamide (CPA), ifosfamide (IFO), and trofosfamide represent an important group of therapeutic agents due to their substantial antitumor and immuno-modulating activity. CPA is widely used as an anticancer drug, an immunosuppressant, and for the mobilization of hematopoetic progenitor cells from the bone marrow into peripheral blood prior to bone marrow transplantation for aplastic anemia, leukemia, and other malignancies. New oxazaphosphorines derivatives have been developed in an attempt to improve selectivity and response with reduced toxicity. These derivatives include mafosfamide (NSC 345842), glufosfamide (D19575, beta-D-glucosylisophosphoramide mustard), NSC 612567 (aldophosphamide perhydrothiazine), and NSC 613060 (aldophosphamide thiazolidine). This review highlights the metabolism and transport of these oxazaphosphorines (mainly CPA and IFO, as these two oxazaphosphorine drugs are the most widely used alkylating agents) and the clinical implications. Both CPA and IFO are prodrugs that require activation by hepatic cytochrome P450 (CYP)-catalyzed 4-hydroxylation, yielding cytotoxic nitrogen mustards capable of reacting with DNA molecules to form crosslinks and lead to cell apoptosis and/or necrosis. Such prodrug activation can be enhanced within tumor cells by the CYP-based gene directed-enzyme prodrug therapy (GDEPT) approach. However, those newly synthesized oxazaphosphorine derivatives such as glufosfamide, NSC 612567 and NSC 613060, do not need hepatic activation. They are activated through other enzymatic and/or non-enzymatic pathways. For example, both NSC 612567 and NSC 613060 can be activated by plain phosphodiesterase (PDEs) in plasma and other tissues or by the high-affinity nuclear 3'-5' exonucleases associated with DNA polymerases, such as DNA polymerases and epsilon. The alternative CYP-catalyzed inactivation pathway by N-dechloroethylation generates the neurotoxic and nephrotoxic byproduct chloroacetaldehyde (CAA). Various aldehyde dehydrogenases (ALDHs) and glutathione S-transferases (GSTs) are involved in the detoxification of oxazaphosphorine metabolites. The metabolism of oxazaphosphorines is auto-inducible, with the activation of the orphan nuclear receptor pregnane X receptor (PXR) being the major mechanism. Oxazaphosphorine metabolism is affected by a number of factors associated with the drugs (e.g., dosage, route of administration, chirality, and drug combination) and patients (e.g., age, gender, renal and hepatic function). Several drug transporters, such as breast cancer resistance protein (BCRP), multidrug resistance associated proteins (MRP1, MRP2, and MRP4) are involved in the active uptake and efflux of parental oxazaphosphorines, their cytotoxic mustards and conjugates in hepatocytes and tumor cells. Oxazaphosphorine metabolism and transport have a major impact on pharmacokinetic variability, pharmacokinetic-pharmacodynamic relationship, toxicity, resistance, and drug interactions since the drug-metabolizing enzymes and drug transporters involved are key determinants of the pharmacokinetics and pharmacodynamics of oxazaphosphorines. A better understanding of the factors that affect the metabolism and transport of oxazaphosphorines is important for their optional use in cancer chemotherapy.

Ifosfamide in Advanced/Disseminated Breast Cancer

Ifosfamide is an alkylating agent active in various tumor types including breast cancer. The availability of mesna (sodium 2-mercaptoethanesulfonate) has increased its safety, avoiding the main dose-limiting side effect, urotoxicity. Interesting activity as a single agent, with response rates ranging from 7 to 30%, is reported in pretreated patients; more attractive data derived from phase II studies on ifosfamide combined with drugs known to be active in advanced breast cancer show response rates always over 35%. This review has taken in consideration papers published after 1995 and available on PubMed medline: the data indicate a potential usefulness of ifosfamide in the clinical management of advanced breast cancer, even if the exact therapeutic role of the drug in this setting should be derived from randomized studies not yet available.

Antiblastic Drug Combinations with Ifosfamide: An Update

Ifosfamide is an alkylating agent that is widely used in the treatment of various neoplasms, such as sarcomas, lymphomas, pediatric malignancies, germ cell tumors, lung, breast and ovarian cancer. The clinical toxicity of ifosfamide depends on the dose and administration schedules. The pharmacologic features of this drug enable its combination with other antiblastic agents, such as vinorelbine, gemcitabine, paclitaxel and docetaxel. Moreover, the pharmacologic profile of ifosfamide allows the use of this antiblastic drug in patients who have previously failed many other treatments, and a large percentage of responses has already been obtained. There is some concern about the optimal scheduling of the drug with other novel chemotherapeutics. Clinical trials that include pharmacokinetic and pharmacodynamic studies may be the most efficient way to optimize the therapeutic efficacy of ifosfamide and define the dosing and scheduling.