In vitro chemosensitivity testing of the feline large granular lymphocyte cell line (S87)

BACKGROUND

Feline large granular lymphocyte (LGL) lymphoma is an aggressive neoplasia characterised by short survival and poor response to chemotherapy.

OBJECTIVES

In this study, the effect of different chemotherapeutic agents on the growth kinetics of the feline cell line S87, a non-MHC-restricted feline LGL cell line, was investigated. Where possible, IC50 (inhibitory concentration 50) values were determined. The IC50 values of the cell line as lymphoma models can provide clues to the situation in vivo and serve as a basis for studying resistance mechanisms.

METHODS

Cells were incubated with various concentrations of vincristine, doxorubicin, 4-hydroperoxycyclophosphamide, prednisolone, methotrexate and L-asparaginase for 24 and 48 h, respectively.

RESULTS

The IC50 values could be determined as 14.57 (7.49-28.32) μg/mL at 24 h incubation and 5.72 (4.05-8.07) μg/mL at 48 h incubation for doxorubicin and 9.12 (7.72-10.76) μg/mL at 24 h incubation and 4.53 (3.74-5.47) μg/mL at 48 h incubation for 4-hydroperpoxycyclophosphamide. Treatment with vincristine and methotrexate resulted in relatively high cell resistance whereas L-asparaginase and prednisolone treatment led to a reduction in cell number compared to control while cell viability was not affected (cytostatic effect).

CONCLUSION

Overall, the feline LGL cell line S87 proves to be relatively sensitive to doxorubicin and 4-hydroperoxycyclophosphamide and relatively resistant to treatment with vincristine, prednisolone, methotrexate and L-asparaginase. The results of this study can be used for further investigations on resistance mechanisms in feline LGL lymphoma. Doxorubicin and cyclophosphamide can be interpreted as promising candidates for the therapy of feline LGL lymphomas.

Exposure-Toxicity Association of Cyclophosphamide and Its Metabolites in Infants and Young Children with Primary Brain Tumors: Implications for Dosing

PURPOSE

To characterize the population pharmacokinetics of cyclophosphamide, active 4-hydroxy-cyclophosphamide (4OH-CTX), and inactive carboxyethylphosphoramide mustard (CEPM), and their associations with hematologic toxicities in infants and young children with brain tumors. To use this information to provide cyclophosphamide dosing recommendations in this population.

PATIENTS AND METHODS

Patients received four cycles of a 1-hour infusion of 1.5 g/m² cyclophosphamide. Serial samples were collected to measure cyclophosphamide, 4OH-CTX, and CEPM plasma concentrations. Population pharmacokinetic modeling was performed to identify the patient characteristics influencing drug disposition. Associations between drug exposures and metrics reflecting drug-induced neutropenia, erythropenia, and thrombocytopenia were investigated. A Bayesian approach was developed to predict 4OH-CTX exposure using only cyclophosphamide and CEPM plasma concentrations.

RESULTS

Data from 171 patients (0.07-4.9 years) were adequately fitted by a two-compartment (cyclophosphamide) and one-compartment model (metabolites). Young infants (<6 months) exhibited higher mean 4OH-CTX exposure than did young children (138.4 vs. 107.2 μmol/L·h, P < 0.0001). No genotypes exhibited clinically significant influence on drug exposures. Worse toxicity metrics were significantly associated with higher 4OH-CTX exposures. Dosing simulations suggested decreased cyclophosphamide dosage to 1.2 g/m² for young infants versus 1.5 g/m² for children to attain similar 4OH-CTX exposure. Bayesian-modeled 4OH-CTX exposure predictions were precise (mean absolute prediction error 14.8% ± 4.2%) and had low bias (mean prediction error 4.9% ± 5.1%).

CONCLUSIONS

A 4OH-CTX exposure-toxicity association was established, and a decreased cyclophosphamide dosage for young infants was suggested to reduce toxicity in this population. Bayesian modeling to predict 4OH-CTX exposure may reduce clinical processing-related costs and provide insights into further exposure-response associations.

Adaptogens in chemobrain (Part II): Effect of plant extracts on chemotherapy-induced cytotoxicity in neuroglia cells

BACKGROUND

Cancer chemotherapy-induced cognitive impairments are apparently associated with harmful effects on physiological functions of brain cells. Adaptogens, are known to exhibit neuroprotective effects and to increase cognitive functions in clinical studies. In our previous study (Seo et al., 2018), we demonstrated that selected adaptogenic extracts significantly attenuate cytostatic-induced regulation of more than 100 genes involved in the activation of neuronal death and inhibiting neurogenesis. Neuroprotective and cytoprotective activities of adaptogens rise the question about their possible impact on cytostatic effects of a chemotherapeutic combination of 5-fluorouracil, epirubicin and cyclophosphamide (FEC).

AIM

The aim of this study was to assess the effects of selected adaptogenic herbal extracts, namely of andrographolide (AND), Herba Andrographidis (AP), Radix Eleutherococci (ES) genuine extracts, their fixed combination (AE), and the combination of three adaptogenic herbs, Rhodiola Radix, Shisandra Fructus and Eleutherococci Radix (RSE) on the cytotoxicity of a fixed combination of 5-fluorouracil, epirubicin and cyclophosphamide (FEC) on neuroglia cells.

METHODS

Cytotoxicity of FEC, adaptogenic extracts and their combination with FEC was tested on isolated T98G cells in a wide range of concentrations of all tested compounds.

RESULTS

FEC reproducibly inhibited the proliferation of T98G cells by 50% at concentrations of 5 × 10^-1 µg/ml epirubicin, 500 × 10^-1 µg/ml 5-fluorouracil and 20 × 10^-1 µg/ml 4-hydroperoxycyclophosphamide after 24 h incubation of cells. These concentrations were subsequently used for experiments with adaptogenic extracts. The cytotoxic activity of FEC was not significantly changed in the presence of AND, ES and AE. Furthermore, it was potentiated by AP extract and RSE in concentrations of 0.06-6 µg/ml and 17.6-26.4 µg/ml.

CONCLUSION

The neuroprotective effect of adaptogens did not attenuate the cytotoxic activity of FEC. Application of cytostatic drugs in combination with adaptogenic plant extracts likely have no impact in cytotoxic effect of FEC. Furthermore, AP and RSE potentiated the cytotoxic effects of FEC.

Trofosfamide in the treatment of elderly or frail patients with diffuse large B-cell lymphoma

PURPOSE

The introduction of immunochemotherapy has led to a significant improvement in treatment results and prognosis of diffuse large B-cell non-Hodgkins lymphoma (DLBCL) both at initial diagnosis and in relapse. Trofosfamide, an oxazaphosphorine derivative, has been utilized as alternative treatment option for patients with lymphoproliferative diseases unsuitable for conventional chemotherapy agents and protocols because of age, comorbidity, or poor performance score. While data on the activity and safety of single-agent trofosfamide have been published, the potential value of this agent in immunochemotherapy in combination with anti-CD20 antibodies such as rituximab has not been investigated to our knowledge.

METHODS

Safety and therapeutic effectiveness of trofosfamide given orally at a dose of 50 mg twice daily alone, or in combination with standard-dose rituximab, was investigated in a cohort of elderly and/or highly comorbid patients with histologically confirmed primary or secondary DLBCL.

RESULTS

Treatment with trofosfamide in this combination setting was generally well tolerated with no treatment-related deaths and manageable side effects, most of which were WHO class I-II; the most clinically relevant toxicity was cytopenia. 19 of 21 examined patients responded to therapy with 11 of 21 (52.4%) achieving a complete remission (CR). Median overall and progression-free survival (OS and PFS) in the CR-group was 14 and 9 months, respectively. In the subgroup with trofosfamide-based first-line therapy, 7 of 10 (70%) achieved CR and median PFS was not reached.

CONCLUSIONS

Immunochemotherapy with rituximab and trofosfamide (RT) is safe and effective in elderly and poor-performance patients with DLBCL. Response rates are comparable to most commonly used primary and salvage treatment protocols. The potential value of TR regimen in both first-line and relapsed/refractory DLCBL merits further investigation and is probably underestimated.

Cyclophosphamide and Iphosphamide against Lewis Lung Carcinoma: Evaluation of Toxic and Therapeutic Effects

In the present report, investigations have been carried out to evaluate toxic and therapeutic effects of cyclophosphamide vs its isomer iphosphamide. Cytostatic action of the 2 drugs was assayed on the murine Lewis lung carcinoma (3LL). It has been observed that iphosphamide is less toxic as compared to cyclophosphamide [Formula: see text]; on the other hand, to reach the same therapeutic effectiveness on 3LL, an iphosphamide dose 1.6 - 2 times higher than that of its parent compound is necessary.

Pharmacokinetics of cyclophosphamide and 4-hydroxycyclophosphamide in cats after oral, intravenous, and intraperitoneal administration of cyclophosphamide

OBJECTIVE To characterize pharmacokinetics of cyclophosphamide and 4-hydoxycyclophosphamide (4-OHCP) in the plasma of healthy cats after oral, IV, and IP administration of cyclophosphamide. ANIMALS 6 healthy adult cats. PROCEDURES Cats were randomly assigned to receive cyclophosphamide (200 mg/m²) via each of 3 routes of administration (oral, IV, and IP); there was a 30-day washout period between successive treatments. Plasma samples were obtained at various time points for up to 8 hours after administration. Samples were treated with semicarbazide hydrochloride to trap the 4-OHCP in stable form, which allowed for cyclophosphamide and trapped 4-OHCP to be simultaneously measured by use of tandem mass spectrometry. Pharmacokinetic parameters were determined from drug concentration-versus-time data for both cyclophosphamide and 4-OHCP. RESULTS Cyclophosphamide was tolerated well regardless of route of administration. Pharmacokinetic parameters for 4-OHCP were similar after oral, IV, and IP administration. Area under the concentration-time curve for cyclophosphamide was lower after oral administration than after IV or IP administration. CONCLUSIONS AND CLINICAL RELEVANCE Cyclophosphamide can be administered interchangeably to cats as oral, IV, and IP formulations, which should provide benefits with regard to cost and ease of administration to certain feline patients.

In Vitro Pre-Clinical Validation of Suicide Gene Modified Anti-CD33 Redirected Chimeric Antigen Receptor T-Cells for Acute Myeloid Leukemia

Background

Approximately fifty percent of patients with acute myeloid leukemia can be cured with current therapeutic strategies which include, standard dose chemotherapy for patients at standard risk of relapse as assessed by cytogenetic and molecular analysis, or high-dose chemotherapy with allogeneic hematopoietic stem cell transplant for high-risk patients. Despite allogeneic hematopoietic stem cell transplant about 25% of patients still succumb to disease relapse, therefore, novel strategies are needed to improve the outcome of patients with acute myeloid leukemia.

Methods and findings

We developed an immunotherapeutic strategy targeting the CD33 myeloid antigen, expressed in ~ 85–90% of patients with acute myeloid leukemia, using chimeric antigen receptor redirected T-cells. Considering that administration of CAR T-cells has been associated with cytokine release syndrome and other potential off-tumor effects in patients, safety measures were here investigated and reported. We genetically modified human activated T-cells from healthy donors or patients with acute myeloid leukemia with retroviral supernatant encoding the inducible Caspase9 suicide gene, a ΔCD19 selectable marker, and a humanized third generation chimeric antigen receptor recognizing human CD33. ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells had a 75±3.8% (average ± standard error of the mean) chimeric antigen receptor expression, were able to specifically lyse CD33⁺ targets in vitro, including freshly isolated leukemic blasts from patients, produce significant amount of tumor-necrosis-factor-alpha and interferon-gamma, express the CD107a degranulation marker, and proliferate upon antigen specific stimulation. Challenging ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells with programmed-death-ligand-1 enriched leukemia blasts resulted in significant killing like observed for the programmed-death-ligand-1 negative leukemic blasts fraction. Since the administration of 10 nanomolar of a non-therapeutic dimerizer to activate the suicide gene resulted in the elimination of only 76.4±2.0% gene modified cells in vitro, we found that co-administration of the dimerizer with either the BCL-2 inhibitor ABT-199, the pan-BCL inhibitor ABT-737, or mafosfamide, resulted in an additive effect up to complete cell elimination.

Conclusions

This strategy could be investigated for the safety of CAR T-cell applications, and targeting CD33 could be used as a ‘bridge” therapy for patients coming to allogeneic hematopoietic stem cell transplant, as anti-leukemia activity from infusing CAR.CD33 T-cells has been demonstrated in an ongoing clinical trial. Albeit never performed in the clinical setting, our future plan is to investigate the utility of iC9-CAR.CD33 T-cells as part of the conditioning therapy for an allogeneic hematopoietic stem cell transplant for acute myeloid leukemia, together with other myelosuppressive agents, whilst the activation of the inducible Caspase9 suicide gene would grant elimination of the infused gene modified T-cells prior to stem cell infusion to reduce the risk of engraftment failure as the CD33 is also expressed on a proportion of the donor stem cell graft.

In vitro testing of drug combinations employing nilotinib and alkylating agents with regard to pretransplant conditioning treatment of advanced-phase chronic myeloid leukemia

PURPOSE

The prognosis of patients with advanced-phase chronic myeloid leukemia (CML) remains dismal despite the availability of targeted therapies and allogeneic stem cell transplantation (allo-SCT). Increasing the antileukemic efficacy of the pretransplant conditioning regimen may be a strategy to increase remission rates and duration. We therefore investigated the antiproliferative effects of nilotinib in combination with drugs that are usually used for conditioning: the alkylating agents mafosfamide, treosulfan, and busulfan.

METHODS

Drug combinations were tested in vitro in different imatinib-sensitive and imatinib-resistant BCR-ABL-positive cell lines. A tetrazolium-based MTT assay was used for the assessment and quantification of growth inhibition after exposure to alkylating agents alone or to combinations with nilotinib. Drug interaction was analyzed using the median-effect method of Chou and Talalay, and combination index (CI) values were calculated according to the classic isobologram equation.

RESULTS

Treatment of imatinib-sensitive, BCR-ABL-positive K562 and LAMA84 cells with nilotinib in combination with mafosfamide, treosulfan, or busulfan resulted in synergistic (CI < 1), additive (CI ~ 1), and predominantly antagonistic (CI > 1) effects, respectively. In imatinib-resistant K562-R and LAMA84-R cells, all applied drug combinations were synergistic (CI < 1) at higher growth inhibition levels.

CONCLUSIONS

Our in vitro data warrant further investigation and may provide the basis for nilotinib-supplemented conditioning regimens for allo-SCT in advanced-phase CML.

Purine analog-like properties of bendamustine underlie rapid activation of DNA damage response and synergistic effects with pyrimidine analogues in lymphoid malignancies

Bendamustine has shown considerable clinical activity against indolent lymphoid malignancies as a single agent or in combination with rituximab, but combination with additional anti-cancer drugs may be required for refractory and/or relapsed cases as well as other intractable tumors. In this study, we attempted to determine suitable anti-cancer drugs to be combined with bendamustine for the treatment of mantle cell lymphoma, diffuse large B-cell lymphoma, aggressive lymphomas and multiple myeloma, all of which are relatively resistant to this drug, and investigated the mechanisms underlying synergism. Isobologram analysis revealed that bendamustine had synergistic effects with alkylating agents (4-hydroperoxy-cyclophosphamide, chlorambucil and melphalan) and pyrimidine analogues (cytosine arabinoside, gemcitabine and decitabine) in HBL-2, B104, Namalwa and U266 cell lines, which represent the above entities respectively. In cell cycle analysis, bendamustine induced late S-phase arrest, which was enhanced by 4-hydroperoxy-cyclophosphamide, and potentiated early S-phase arrest by cytosine arabinoside (Ara-C), followed by a robust increase in the size of sub-G1 fractions. Bendamustine was able to elicit DNA damage response and subsequent apoptosis faster and with shorter exposure than other alkylating agents due to rapid intracellular incorporation via equilibrative nucleoside transporters (ENTs). Furthermore, bendamustine increased the expression of ENT1 at both mRNA and protein levels and enhanced the uptake of Ara-C and subsequent increase in Ara-C triphosphate (Ara-CTP) in HBL-2 cells to an extent comparable with the purine analog fludarabine. These purine analog-like properties of bendamustine may underlie favorable combinations with other alkylators and pyrimidine analogues. Our findings may provide a theoretical basis for the development of more effective bendamustine-based combination therapies.

Quantitative analysis of the anti-proliferative activity of combinations of selected iron-chelating agents and clinically used anti-neoplastic drugs

Recent studies have demonstrated that several chelators possess marked potential as potent anti-neoplastic drugs and as agents that can ameliorate some of the adverse effects associated with standard chemotherapy. Anti-cancer treatment employs combinations of several drugs that have different mechanisms of action. However, data regarding the potential interactions between iron chelators and established chemotherapeutics are lacking. Using estrogen receptor-positive MCF-7 breast cancer cells, we explored the combined anti-proliferative potential of four iron chelators, namely: desferrioxamine (DFO), salicylaldehyde isonicotinoyl hydrazone (SIH), (E)-N'-[1-(2-hydroxy-5-nitrophenyl)ethyliden] isonicotinoyl hydrazone (NHAPI), and di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), plus six selected anti-neoplastic drugs. These six agents are used for breast cancer treatment and include: paclitaxel, 5-fluorouracil, doxorubicin, methotrexate, tamoxifen and 4-hydroperoxycyclophosphamide (an active metabolite of cyclophosphamide). Our quantitative chelator-drug analyses were designed according to the Chou-Talalay method for drug combination assessment. All combinations of these agents yielded concentration-dependent, anti-proliferative effects. The hydrophilic siderophore, DFO, imposed antagonism when used in combination with all six anti-tumor agents and this antagonistic effect increased with increasing dose. Conversely, synergistic interactions were observed with combinations of the lipophilic chelators, NHAPI or Dp44mT, with doxorubicin and also the combinations of SIH, NHAPI or Dp44mT with tamoxifen. The combination of Dp44mT with anti-neoplastic agents was further enhanced following formation of its redox-active iron and especially copper complexes. The most potent combinations of Dp44mT and NHAPI with tamoxifen were confirmed as synergistic using another estrogen receptor-expressing breast cancer cell line, T47D, but not estrogen receptor-negative MDA-MB-231 cells. Furthermore, the synergy of NHAPI and tamoxifen was confirmed using MCF-7 cells by electrical impedance data, a mitochondrial inner membrane potential assay and cell cycle analyses. This is the first systematic investigation to quantitatively assess interactions between Fe chelators and standard chemotherapies using breast cancer cells. These studies are vital for their future clinical development.

[Anti-tumor effects of a novel cyclophosphamide derivate 9b in vivo and in vitro]

This study is to investigate the anti-tumor activities of a novel cyclophosphamide derivate 4, 6-diphenyl cyclophosphamide (9b) in vivo and in vitro, and its possible mechanism of action. The inhibitory effects of 9b on human hepatoma cell line HepG2, human breast carcinoma cell line MCF-7 and human myeloid leukemia cell line K562 were measured by MTT assay in vitro. Cell cycle distribution and apoptotic rate were evaluated by flow cytometry. To evaluate the anti-tumor effect of 9b in vivo, mouse model bearing inoculated H22 tumor was established. The results indicated that 9b could inhibit the proliferation of HepG2, MCF-7 and K562 cells in a dose and time dependent manner. The ICo50 values of 9b were 32.34 micromol.L-1 to HepG2 cells, 87.07 micromol.L-1 to MCF-7 cells and 149.10 micromol.L-1 to K562 cells after incubation for 48 h. The results of flow cytometry indicated that after being treated for 48 h with different concentrations of 9b, the ratios of HepG2, MCF-7 cells at the Go/G1 phase and K562 cells at the G0/Gl phase and G2/M phase increased significantly compared with control group, and the apoptotic rate increased with the increase of the concentration of 9b. 9b could significantly reduce tumor weight of H22 solid tumor mouse model in vivo. To summarize, 9b showed significantly anti-tumor activity in vivo and in vitro, of which the mechanism might be associated with the change of cell cycle distribution and induction of tumor cell apoptosis.

Human CD4+CD25+ regulatory T cells are sensitive to low dose cyclophosphamide: implications for the immune response

Regulatory T cells (Treg) play a pivotal role in the immune system since they inhibit the T cell response. It is well known that cyclophosphamide applied at low dose is able to stimulate the immune response while high dose cyclophosphamide exerts inhibitory activity. Data obtained in mice indicate that cyclophosphamide provokes a reduction in the number of Treg and impairs their suppressive activity, resulting in immune stimulation. Here, we addressed the question of the sensitivity of human Treg to cyclophosphamide, comparing Treg with cytotoxic T cells (CTL) and T helper cells (Th). We show that Treg are more sensitive than CTL and Th to mafosfamide, which is an active derivative of cyclophosphamide, which does not need metabolic activation. The high sensitivity of Treg was due to the induction of apoptosis. Treg compared to CTL and Th were not more sensitive to the alkylating drugs temozolomide and nimustine and also not to mitomycin C, indicating a specific Treg response to mafosfamide. The high sensitivity of Treg to mafosfamide resulted not only in enhanced cell death, but also in impaired Treg function as demonstrated by a decline in the suppressor activity of Treg in a co-culture model with Th and Helios positive Treg. Treatment of Treg with mafosfamide gave rise to a high level of DNA crosslinks, which were not repaired to the same extent as observed in Th and CTL. Also, Treg showed a low level of γH2AX foci up to 6 h and a high level 24 h after treatment, indicating alterations in the DNA damage response. Overall, this is the first demonstration that human Treg are, in comparison with Th and CTL, hypersensitive to cyclophosphamide, which is presumably due to a DNA repair defect.

In vitro cytotoxicity testing of new generation oxazaphosphorines against human histiocytic lymphoma cells

Oxazaphosphorines belong to a group of alkylating agents. Mafosfamide cyclohexylamine salt (D-17272), 4-hydro-peroxy-cyclophosphamide (D-18864) and glufosfamide (D-19575, beta-D-glucose-isophosphoramide mustard) are new generation oxazaphosphorines. The objective of the present study was to compare the cytotoxic action of these oxazaphosphorine compounds against human histiocytic lymphoma U937 cells. The chemical structures of the oxazaphosphorines were responsible for the different responses of U937 cells. The cytotoxic effects of D-17272, D-18864, and D-19575 on U937 cells depended on the agent tested, its dose, and the time intervals after the oxazaphosphorine application. Among the oxazaphosphorine agents, D-18864 appeared to be the most cytotoxic, and D-19575 was characterized by the lowest cytotoxicity. The in vitro cytotoxic activities of the oxazaphosphorines were strongly associated with their cell death inducing potential.

Using rituximab plus fludarabine and cyclophosphamide as a treatment for refractory mixed cryoglobulinemia associated with lymphoma

OBJECTIVE

Treatment of refractory mixed cryoglobulinemia (MC) with severe organ involvement remains challenging. Fludarabine, cyclophosphamide, and rituximab (FCR) treatment is highly effective for patients with chronic lymphocytic leukemia and marginal-zone lymphoma. We first report the safety and efficacy of FCR treatment in severe and refractory MC vasculitis associated with lymphoma.

METHODS

We report the safety and efficacy of fludarabine (40 mg/m(2) orally on days 2-4), cyclophosphamide (250 mg/m(2) orally on days 2-4), and rituximab (375 mg/m(2) on day 1), every 4 weeks, for 3 to 6 cycles in 7 consecutive patients with severe and refractory MC.

RESULTS

Clinical features of MC included purpura (n = 7), polyneuropathy (n = 6), and kidney (n = 4) and cardiac involvement (n = 2). Previous treatment included rituximab (n = 5), corticosteroids (n = 5), antiviral therapy (n = 5), cyclophosphamide (n = 3), and plasmapheresis (n = 2). All patients achieved clinical response, with 3 patients (42.9%) achieving a complete remission and 4 patients (57.1%) a partial remission. Cryoglobulin decreased from 0.94 to 0.41 gm/liter (P = 0.015). After a followup of 27 months, 2 patients experienced a relapse of MC. Five patients (71.4%) experienced side effects, including cytopenia (n = 5), pneumopathy (n = 2), and serum sickness (n = 1).

CONCLUSION

The FCR regimen represents an effective treatment in severe and refractory MC.

Pilot study of systemic and intrathecal mafosfamide followed by conformal radiation for infants with intracranial central nervous system tumors: a pediatric brain tumor consortium study (PBTC-001)

A pilot study to investigate the feasibility of the addition of intrathecal (IT) mafosfamide to a regimen of concomitant multi-agent systemic chemotherapy followed by conformal radiation therapy (RT) for children <3 years with newly diagnosed embryonal CNS tumors was performed. Ninety-three newly diagnosed infants and children (<3 years) with embryonal CNS tumors were enrolled. Twenty weeks of systemic multi-agent chemotherapy commenced within 35 days of surgery. Patients without CSF flow obstruction (n = 71) received IT mafosfamide (14 mg) with chemotherapy. Localized (M(0)) patients with SD or better subsequently received RT followed by 20 additional weeks of chemotherapy. Second look surgery was encouraged prior to RT if there was an incomplete surgical resection at diagnosis. 71 evaluable patients with normal CSF flow received IT Mafosfamide with systemic chemotherapy; patients with M + disease were removed from protocol therapy at 20 weeks and those with PD at the time of progression. One and 5-year progression free survival (PFS) and overall survival (OS) for the cohort of 71 evaluable patients were 52 ± 6.5 % and 33 ± 13 %, and 67 ± 6.2 % and 51 ± 11 %, respectively. The 1-year Progression Free Survival (PFS) for M0 patients with medulloblastoma (MB, n = 20), supratentorial primitive neuroectodermal tumor (PNET, n = 9), and atypical teratoid rhabdoid tumor (ATRT, n = 12) was 80 ± 7 %, 67 ± 15 % and 27 ± 13 % and 5-year PFS was 65 ± 19 %, 37 ± 29 %, and 0 ± 0 %, respectively. The addition of IT mafosfamide to systemic chemotherapy in infants with embryonal CNS tumors was feasible. The PFS for M0 patients appears comparable to or better than most prior historical comparisons and was excellent for those receiving conformal radiotherapy.

Mafosfamide as a new anticancer agent: preclinical investigations and clinical trials

Mafosfamide (4-thioethane sulfonic acid salt of 4-hydroxy-cyclophosphamide, MAF) belongs to a new generation of the oxazaphosphorine agents. MAF is a cyclophosphamide analog which spontaneously degrades to 4-hydroxy-cyclophosphamide. The effects of MAF on various types of cancer cells were determined during preclinical investigations and clinical trials. The positive results from in vitro and in vivo anticancer studies promoted MAF to a good candidate for phase I trials. Clinical experience with intrathecal MAF, used for patients with neoplastic meningitis due to leukemia, lymphoma, and solid tumors, indicated good tolerability and efficacy. The recommended phase II doses of intrathecally administered MAF were determined. Clinical trials using intrathecal MAF are now underway. To obtain a better therapeutic index, a strategy to alternate dosing between the intraventricular and intralumbar routes is also being tested. MAF is an attractive agent for regional cancer therapy. The current available knowledge on MAF as a new anticancer agent is based on a collection of the original published studies, conference abstracts and relevant articles.

TRAIL and taurolidine enhance the anticancer activity of doxorubicin, trabectedin and mafosfamide in HT1080 human fibrosarcoma cells

BACKGROUND

Disseminated fibrosarcoma still represents a therapeutic dilemma because of lack of effective cytostatics. Therefore we tested tumor necrosis factor related apoptosis-inducing ligand (TRAIL) and taurolidine, in combination with established and new chemotherapeutic agents on human fibrosarcoma (HT1080).

MATERIALS AND METHODS

Human fibrosarcoma cells (HT1080) were incubated with doxorubicin, mafosfamide and trabectedin both alone and in combination with taurolidine and TRAIL. Vital, apoptotic and necrotic cells were quantified using flow cytometric analysis. Cell proliferation was analysed using a bromodeoxyuridine (BrdU) ELISA assay.

RESULTS

Single application of doxorubicin and trabectedin induced apoptotic cell death and significantly reduced the proliferation of HT1080 cells. In combination treatment, the addition of taurolidine and TRAIL resulted in a stronger reduction in the degree of cell viability when compared to single treatment. Trabectedin and taurolidine displayed a greater potential for inhibiting proliferation than did doxorubicin alone.

CONCLUSION

When combined with TRAIL and taurolidine, treatment with doxorubicin and trabectedin demonstrated stronger apoptosis-inducing and antiproliferative effects.

The enzymatic activity of human aldehyde dehydrogenases 1A2 and 2 (ALDH1A2 and ALDH2) is detected by Aldefluor, inhibited by diethylaminobenzaldehyde and has significant effects on cell proliferation and drug resistance

There has been a new interest in using aldehyde dehydrogenase (ALDH) activity as one marker for stem cells since the Aldefluor flow cytometry-based assay has become available. Diethylaminobenzaldehyde (DEAB), used in the Aldeflour assay, has been considered a specific inhibitor for ALDH1A1 isoform. In this study, we explore the effects of human ALDH isoenzymes, ALDH1A2 and ALDH2, on drug resistance and proliferation, and the specificity of DEAB as an inhibitor. We also screened for the expression of 19 ALDH isoenzymes in K562 cells using TaqMan Low Density Array (TLDA). We used lentiviral vectors containing the full cDNA length of either ALDH2 or ALDH1A2 to over express the enzymes in K562 leukemia and H1299 lung cancer cell lines. Successful expression was measured by activity assay, Western blot, RT-PCR, and Aldefluor assay. Both cell lines, with either ALDH1A2 or ALDH2, exhibited higher cell proliferation rates, higher clonal efficiency, and increased drug resistance to 4-hydroperoxycyclophosphamide and doxorubicin. In order to study the specificity of known ALDH activity inhibitors, DEAB and disulfiram, we incubated each cell line with either inhibitor and measured the remaining ALDH enzymatic activity. Both inhibitors reduced ALDH activity of both isoenzymes by 65-90%. Furthermore, our TLDA results revealed that ALDH1, ALDH7, ALDH3 and ALDH8 are expressed in K562 cells. We conclude that DEAB is not a specific inhibitor for ALDH1A1 and that Aldefluor assay is not specific for ALDH1A1 activity. In addition, other ALDH isoenzymes seem to play a major role in the biology and drug resistance of various malignant cells.

Antiangiogenesis enhances intratumoral drug retention

The tumor vasculature delivers nutrients, oxygen, and therapeutic agents to tumor cells. Unfortunately, the delivery of anticancer drugs through tumor blood vessels is often inefficient and can constitute an important barrier for cancer treatment. This barrier can sometimes be circumvented by antiangiogenesis-induced normalization of tumor vasculature. However, such normalizing effects are transient; moreover, they are not always achieved, as shown here, when 9L gliosarcoma xenografts were treated over a range of doses with the VEGF receptor-selective tyrosine kinase inhibitors axitinib and AG-028262. The suppression of tumor blood perfusion by antiangiogenesis agents can be turned to therapeutic advantage, however, through their effects on tumor drug retention. In 9L tumors expressing the cyclophosphamide-activating enzyme P450 2B11, neoadjuvant axitinib treatment combined with intratumoral cyclophosphamide administration significantly increased tumor retention of cyclophosphamide and its active metabolite, 4-hydroxycyclophosphamide. Similar increases were achieved using other angiogenesis inhibitors, indicating that increased drug retention is a general response to antiangiogenesis. This approach can be extended to include systemic delivery of an anticancer prodrug that is activated intratumorally, where antiangiogenesis-enhanced retention of the therapeutic metabolite counterbalances the decrease in drug uptake from systemic circulation, as exemplified for cyclophosphamide. Importantly, the increase in intratumoral drug retention induced by neoadjuvant antiangiogenic drug treatment is shown to increase tumor cell killing and substantially enhance therapeutic activity in vivo. Thus, antiangiogenic agents can be used to increase tumor drug exposure and improve therapeutic activity following intratumoral drug administration, or following systemic drug administration in the case of a therapeutic agent that is activated intratumorally.

In vitro investigation into the potential of a mistletoe extract to alleviate adverse effects of cyclophosphamide

OBJECTIVES

Mistletoe extracts have been shown to provide deoxyribonucleic acid (DNA)-stabilizing effects in human peripheral blood mononuclear cells (PBMC) in vitro. We investigated the effect of a mistletoe extract on PBMC with and without concomitant treatment with cyclophosphamide and compared mitochondrial activity and replication of normal PBMC with that of a T-cell leukemia cell line.

DESIGN

The experiments were performed with PBMC of healthy blood donors and the T-cell leukemia Jurkat cell line. Cells were pre-incubated with mistletoe extract for 60 to 65 hours. 4-hydroperoxycyclophosphamide (4-hpc, precursor of 4-hydroxycyclophosphamide) was added for 2 hours, after which mitochondrial activity and replication were measured. All experiments were randomized and blinded.

MAIN OUTCOME MEASURES

Cell mitochondrial activity and replication were assessed with spectrophotometric analysis of WST-1 reduction and BrdU incorporation.

RESULTS

The application of 4-hpc consistently reduced mitochondrial activity and replication of PBMC and Jurkat cells. Mistletoe extract strongly enhanced PBMC mitochondrial activity and replication (with or without 4-hpc) and partially inhibited Jurkat cell replication (with 4-hpc only). Compared to mistletoe untreated cells, enhancement ofPBMC mitochondrial activity by mistletoe extract was independent of treatment with 4-hpc, but enhancement of PBMC replication by mistletoe extract was stronger when treated with 4-hpc.

CONCLUSIONS

Mistletoe extract strongly stimulated healthy PBMC but not malignant Jurkat cells. In addition, mistletoe extract seemed to partially protect healthy PBMC-but not malignant Jurkat cells-from the cytostatic effect of 4-hpc. The results motivate further preclinical and clinical investigations of mistletoe extracts as an adjuvant medication in cancer therapy to alleviate side effects of conventional therapy.

Gas-fragmentation study of the novel synthetic zwitterionic drug 3-methyl-9-(2-oxa-2lambda5-2H-1,3,2-oxazaphosphorine-2-cyclohexyl)-3,6,9-triazaspiro[5,5]undecane chloride (SLXM-2) by electrospray ionization tandem mass spectrometry

The zwitterionic drug 3-methyl-9-(2-oxa-2lambda5-2H-1,3,2-oxazaphosphorine-2-cyclohexyl)-3,6,9-triazaspiro[5,5]undecane chloride (SLXM-2) is a novel synthetic compound which has shown anticancer activity and low toxicity in vivo. In this study, the various gas-phase fragmentation routes were analyzed by electrospray ionization mass spectrometry (positive ion mode) in conjunction with tandem mass spectrometry (ESI-MS(n)) for the first time. In ESI-MS the fragment ion at m/z 289 (base peak) was formed by loss of the chlorine anion from the zwitterionic precursor SLXM-2. The fragment ion at m/z 232 was formed from the ion at m/z 289 by loss of 1-methylaziridine. The detailed gas-phase collision-induced dissociation (CID) fragmentation mechanisms obtained from the various precursor ions extracted from the zwitterionic SLXM-2 drug was obtained by tandem mass spectrometry analyses.

Herpesvirus type 7 infection may play an important role in individuals with a genetic profile of susceptibility to Graves' disease

OBJECTIVE

An inherited profile of genes related to the response to aggressive environmental factors such as viruses and chemicals may be related to an increased susceptibility to Graves' disease (GD).

DESIGN AND METHODS

This prospective case-control study was designed to examine the relationship between human herpesviruses (HHV) infection, determined by circulating DNA; tumour protein p53 (TP53) apoptotic ability; and detoxification system genes, and GD. We studied 280 confirmed GD patients paired to 284 controls with respect to environmental exposure. Exclusion criteria included medications that could interfere with thyroid function evaluation and a recent history of viral and bacterial infections.

RESULTS

A stepwise regression analysis adjusted for age, gender, and ethnicity established the inheritance of glutathione S-transferase pi 1 (GSTP1) (odds ratio (OR)=3.423; 95% confidence interval (CI)=2.120-5.527; P<0.001) and cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) variants (OR=1.649; 95% CI=1.012-2.686; P=0.0445) as significant risk factors for the disease. HHV-7 infection was much more common in GD patients (64.64%) than in controls (38.73%; chi(2), P<0.0001), and it increased the risk for GD more than three times (OR=3.133; 95% CI=1.959-5.011; P<0.0001). The inheritance of less efficient Pro/Pro TP53 gene variants significantly increased the risk of GD development (OR=5.196; 95% CI=2.112-12.783; P<0.0001) and also favored HHV-7 infection (OR=2.835; 95% CI=1.100-7.310; P=0.0275). In addition, 72TP53 variants augmented the risk of GD relapse (OR=1.860; 95% CI=1.015-3.410; P=0.0446).

CONCLUSIONS

We suggest that an inherited genetic profile involving TP53 may favor HHV-7 infection and maintenance, which, in turn, may initiate and perpetuate GD autoimmune process.

SRD5A2 V89L polymorphism and prostate cancer risk: a meta-analysis

BACKGROUND

Increasing studies investigating the association between steroid 5-alpha reductase type II gene polymorphism at codon 89 (SRD5A2 V89L) and susceptibility to prostate cancer (PCa) confer inconsistent results. To precisely estimate the relationship with more statistical power, a meta-analysis was performed.

METHODS

A comprehensive search was conducted to identify all case-control studies investigating such an association. Odds ratio (OR) and its 95% confidence interval (CI) were used to evaluate the size effect.

RESULTS

Twenty-five eligible reports were identified including 8,615 cases/9,089 controls in 33 comparisons. In overall analysis, no significant associations were found in all genetic models. Subgroup analyses by ethnicity revealed that small excess PCa risks were observed in dominant model (OR, 1.11; 95% CI, 1.03-1.19 for (LL + VL) vs. VV; P < 0.01; P(heterogeneity) = 0.49) and L allele frequency comparison (OR, 1.09; 1.03-1.15 for L allele frequency; P < 0.01; P(heterogeneity) = 0.07) in Europeans. Meanwhile, SRD5A2 V89L polymorphism was significantly associated with an increased PCa risk in men aged < or =65 under the co-dominant (OR, 1.70; 95% CI, 1.09-2.66 for LL vs. VV; P = 0.02; P(heterogeneity) = 0.31) and recessive (OR, 1.75; 95% CI, 1.14-2.68 for LL vs. (VV + VL); P = 0.01; P(heterogeneity) = 0.12) models. However, no significant associations were found in Asians and Africans.

CONCLUSIONS

Our study suggests SRD5A2 V89L polymorphism could play a low-penetrant role in PCa risk among Europeans and individuals younger than 65 years. Additional well-designed studies are warranted to validate these findings.

Ex vivo treatment of myeloma cells by 4-HC, VP-16, LAK cells and antibodies

To assess the usefulness of 4-hydroperoxycyclophosphamide (4-HC) and Etoposide (VP-16) as a purging agent for myeloma cells in bone marrow ex-vivo, myeloma cell lines (SK-RCS-1, RPMI-8226), lymphoma cell line (SK-DHL-2) and normal bone marrow (BM) cells were treated at different concentrations of 4-HC, VP-16. In separate experiments, LAK cells or antibodies were also used to treat the above cell lines. Clonogenic tumor cells from all three cell lines could be reduced by more than 4 logs, when treated alone or as a mixture with irradiated normal bone marrow cells at a 4-HC concentration of 60 mumol/l. Under similar conditions, approximately 1% of normal BM myeloid progenitor granulocyte-macrophage colony forming cells (CFU-GM) survived. The results with LAK cells and antibodies were also encouraging. These observations support the use of various purging methods for myeloma cells for autologous bone marrow transplantation.

Low-dose oral metronomic chemotherapy prevents mobilization of endothelial progenitor cells into the blood of cancer patients

Circulating endothelial progenitor cells (EPCs) actively supply cells that may participate in tumor angiogenesis. The differing effects of low-dose metronomic trofosfamide as opposed to conventional dose-dense chemotherapy on plasma levels of vascular endothelial growth factor (VEGF) and the numbers of circulating EPC are reported.

PATIENTS AND METHODS

Blood samples were obtained from cancer patients, 18 receiving oral metronomic chemotherapy of trofosfamide with or without celecoxib, and 24 receiving conventional dose-dense chemotherapy, eight of them in adjuvant intention. Mononuclear cells were analyzed by flow cytometry for CD34, CD45 and vascular endothelial growth factor-receptor 2 (VEGF-R2) coexpression, defining EPCs, and for plasma levels of VEGF by ELISA at day 0, 10 and 21 of therapy.

RESULTS

After conventional dose-dense chemotherapy, the numbers of circulating EPCs and the VEGF plasma concentrations increased sharply, doubling pretherapeutic levels at day 21. In contrast, under low-dose metronomic chemotherapy, the numbers of circulating EPCs decreased significantly and VEGF plasma concentrations remained unchanged.

CONCLUSION

These observations provide evidence that conventional dose-dense chemotherapy leads to rebound EPC mobilization even when given with adjuvant intention, while low-dose metronomic scheduling of cytotoxic substances such as trofosfamide may sharply reduce EPC release into the circulation.

Modulation of the antitumor activity of metronomic cyclophosphamide by the angiogenesis inhibitor axitinib

The promising but still limited efficacy of angiogenesis inhibitors as monotherapies for cancer treatment indicates a need to integrate these agents into existing therapeutic regimens. Presently, we investigate the antitumor activity of the small-molecule angiogenesis inhibitor axitinib (AG-013736) and its potential for combination with metronomic cyclophosphamide. Axitinib significantly inhibited angiogenesis in rat 9L tumors grown s.c. in scid mice but only moderately delayed tumor growth. Combination of axitinib with metronomic cyclophosphamide fully blocked 9L tumor growth on initiation of drug treatment. In contrast, metronomic cyclophosphamide alone required multiple treatment cycles to halt tumor growth. However, in contrast to the substantial tumor regression that is ultimately induced by metronomic cyclophosphamide, the axitinib/cyclophosphamide combination was tumor growth static. Axitinib did not inhibit hepatic activation of cyclophosphamide or export of its activated metabolite, 4-hydroxy-cyclophosphamide (4-OH-CPA), to extrahepatic tissues; rather, axitinib selectively decreased 9L tumor uptake of 4-OH-CPA by 30% to 40%. The reduced tumor penetration of 4-OH-CPA was associated with a decrease in cyclophosphamide-induced tumor cell apoptosis and a block in the induction of the endogenous angiogenesis inhibitor thrombospondin-1 in tumor-associated host cells, which may contribute to the absence of tumor regression with the axitinib/cyclophosphamide combination. Finally, axitinib transiently increased 9L tumor cell apoptosis, indicating that its effects are not limited to the endothelial cell population. These findings highlight the multiple effects that may characterize antiangiogenic agent/metronomic chemotherapy combinations and suggest that careful optimization of drug scheduling and dosages will be required to maximize antitumor responses.

Synergy of karenitecin and mafosfamide in pediatric leukemia, medulloblastoma, and neuroblastoma cell lines

BACKGROUND

A major barrier to treatment of leptomeningeal disease is the lack of proven combination chemotherapy regimens for intrathecal administration. The purpose of this study was to determine the cytotoxic effects of karenitecin and mafosfamide in vitro against leukemia, medulloblastoma, and neuroblastoma cell lines.

PROCEDURE

A modified methyl tetrazolium (MTT) assay was used to determine the sensitivity of the cells to karenitecin and mafosfamide. Cells were exposed to drug for 72 hr, after which the number of surviving cells was quantitated. For drug combination experiments, cells were exposed to medium alone (controls), single drugs alone (mafosfamide only, karenitecin only) or to different concentrations of the combination of the two drugs (karenitecin + mafosfamide), for a total of 36 concentration pairs per plate. The universal response surface approach (URSA) was used to analyze the cytotoxic effects of the combination of karenitecin and mafosfamide.

RESULTS

The IC(50)s of karenitecin and mafosfamide for the various cell lines were similar. For both drugs nearly complete inhibition of cell growth was demonstrated at higher concentrations in all cell lines. In the neuroblastoma cell lines (SK-N-DZ; SK-N-SH) and the DAOY medulloblastoma cell line, the combination of karenitecin and mafosfamide were synergistic. In the D283 medulloblastoma and both the leukemia cell lines (JM1 and Molt-4), the drug interaction was additive. Antagonism was not seen in any cell line.

CONCLUSIONS

Karenitecin and mafosfamide are additive or synergistic in vitro against tumor types that disseminate to the leptomeninges. These results provide guidance for the choice of potential combination intrathecal regimens.

5jährige Erfahrungen mit adjuvanter Chemotherapie beim primären Mammakarzinom

In 515 patients with primary carcinoma of the breast T1a-3aN1a-bM0, the authors conducted simple mastectomy with radical lymphonodectomy of the axilla from 1976 onwards to the time of reporting. In 190 patients with affected lymph nodes, assisting chemotherapy was effected with a combination of three drugs, namely, trofosfamide, methotrexate and 5-fluoro-uracil for a period of 12 months postoperatively. Patients whose lymph nodes remained free were not subjected to follow-up treatment. For both groups of patients, the rates of relapses and survival times were established for an average follow-up time of 41 months (15-75). No significant differences in the rates of relapses and localisation were seen on comparing both groups (P = 0.27). In the patients with affected lymph nodes, local relapses were somewhat more frequent than with patients whose lymph nodes were not affected (11.1% vs. 9.8%); the same also applied to the occurrence of metastases distant from the primary tumour (12.1% vs. 7.4%). Significant differences in survival rates in patients with affected lymph nodes were seen only in the tumour stages T1/T2 (P = 0.001) and for the stages T2/T3 (P = 0.009). The menopausal status of the patients did not show any significant differences in respect of probability of survival for both groups (N-:P = 0.75; N+:P = 0.79).

Heterogeneity of aldehyde dehydrogenase expression in lung cancer cell lines is revealed by Aldefluor flow cytometry-based assay

BACKGROUND

We have been interested in studying the roles of two aldehyde dehydrogenases in the biology of lung cancer. In this study, we seek to apply Aldefluor flow cytometry-based assay for the measurement of aldehyde dehydrogenase (ALDH) activity in lung cancer cell lines, which may become a new tool that will facilitate our continued research in this field.

EXPERIMENTAL DESIGN

Several established lung cancer cell lines were used, including A549 cell line expressing siRNA against aldehyde dehydrogenase class-1A1 (ALDH1A1). Western blot analysis, spectrophotometry assay, and Aldefluor staining were used to measure protein or enzyme activity in these cell lines. For the purpose of measurement of ALDH activity by Aldefluor in cells with known high ALDH levels, cells were mixed 1:10 with immortalized lung epithelial cell line (Beas-2B), which is known to lack ALDH activity. To delineate dead cells, double staining using Aldefluor and propidium iodide (PI) was done. Double staining was also used to detect changes in ALDH activity in two different cell lines after treatment with 4-hydroperoxycyclophosphamide (4-HC).

RESULTS

Our results show a very good correlation between Aldefluor, Western blot, and spectrophotometry assays. Mixing experiments with Beas-2B cells allowed accurate assessment of ALDH activity in A549 cells at baseline and after siRNA expression, thus establishing an approach that facilitates the measurement of very high ALDH using the Aldefluor assay. Aldefluor staining was able to detect heterogeneity in ALDH expression among as well as within the same cell lines and better assess viability after 4-HC treatment when combined with PI.

CONCLUSIONS

Aldefluor assay can be adapted successfully to measure ALDH activity in lung cancer cells and may have the advantage of providing real time changes in ALDH activity in viable cells treated with siRNA or chemotherapy.

Dissecting the impact of chemotherapy on the human hair follicle: a pragmatic in vitro assay for studying the pathogenesis and potential management of hair follicle dystrophy

Chemotherapy-induced alopecia represents one of the major unresolved problems of clinical oncology. The underlying molecular pathogenesis in humans is virtually unknown because of the lack of adequate research models. Therefore, we have explored whether microdissected, organ-cultured, human scalp hair follicles (HFs) in anagen VI can be exploited for dissecting and manipulating the impact of chemotherapy on human HFs. Here, we show that these organ-cultured HFs respond to a key cyclophosphamide metabolite, 4-hydroperoxycyclophosphamide (4-HC), in a manner that resembles chemotherapy-induced HF dystrophy as it occurs in vivo: namely, 4-HC induced melanin clumping and melanin incontinence, down-regulated keratinocyte proliferation, massively up-regulated apoptosis of hair matrix keratinocytes, prematurely induced catagen, and up-regulated p53. In addition, 4-HC induced DNA oxidation and the mitochondrial DNA common deletion. The organ culture system facilitated the identification of new molecular targets for chemotherapy-induced HF damage by microarray technology (eg, interleukin-8, fibroblast growth factor-18, and glypican 6). It was also used to explore candidate chemotherapy protectants, for which we used the cytoprotective cytokine keratinocyte growth factor as exemplary pilot agent. Thus, this novel system serves as a powerful yet pragmatic tool for dissecting and manipulating the impact of chemotherapy on the human HF.

Population pharmacokinetics of the BEACOPP polychemotherapy regimen in Hodgkin's lymphoma and its effect on myelotoxicity

BACKGROUND AND OBJECTIVE

The BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine and prednisone) chemotherapy regimen for the treatment of advanced Hodgkin's lymphoma has a superior outcome, but its toxicity (mainly haematotoxicity) is pronounced and highly variable. The present study was conducted to address the role of pharmacokinetics in individual toxicity.

STUDY DESIGN

Three plasma samples and a 24-hour urine collection for day 1 of the first three cycles of chemotherapy were analysed in 30 patients, and the pharmacokinetic parameters of the respective drugs were estimated by population pharmacokinetic methods (nonlinear mixed-effects model [NONMEM] software). Demographic data, doses and durations of infusion were also recorded. The effect of these parameters on platelet counts was estimated by analysis of covariance using a general linear model.

RESULTS

The pharmacokinetic parameters and respective covariates were similar to the published data. The body surface area, peak concentrations of etoposide, urinary recovery of dechloroethylcyclophosphamide (formed by cytochrome P450 [CYP] 3A4) relative to the cyclophosphamide dose and number of cycles had a significant effect on toxicity. These factors explained 37% of the interindividual variability in the change in platelet counts from day 1 to day 8 of each cycle.

CONCLUSION

The results show that the individual pharmacokinetics of BEACOPP drugs are an important link between dosage and toxicity. Accordingly, individualisation of treatment based on pharmacokinetics may result in more uniform toxicity. Individualisation may also allow escalation of the mean dose, which is probably related to better efficacy. As a consequence of the present study, infusion rates should be standardised, and the potential of a dose reduction in the first cycle and of CYP3A4 phenotyping should be addressed in clinical studies.

Genetic polymorphisms of CYP2B6 affect the pharmacokinetics/pharmacodynamics of cyclophosphamide in Japanese cancer patients

OBJECTIVE

To evaluate the effects of genetic polymorphisms of drug metabolizing enzymes on the pharmacokinetics of cyclophosphamide and its active metabolite, 4-hydroxycyclophosphamide, and on the pharmacodynamics.

EXPERIMENTAL DESIGN

One hundred and three Japanese patients with malignant lymphoma or breast cancer treated with cyclophosphamide (500-750 mg/m) participated in this study. The plasma concentrations of cyclophosphamide and 4-hydroxycyclophosphamide were determined by high-performance liquid chromatography, and pharmacokinetic parameters were calculated. The genotypes of CYP2B6, CYP2C19, CYP3A4, CYP3A5, ALDH1A1, GST genes were determined by allele-specific polymerase chain reaction or polymerase chain reaction-restriction-fragment length polymorphism.

RESULTS

A large interindividual difference (54-fold) was observed in the area under the curve ratio of 4-hydroxycyclophosphamide/cyclophosphamide calculated as the metabolic index. We first proved that leukocytopenia and neutropenia were significantly (P<0.01) related to the area under the curve of 4-hydroxycyclophosphamide. We found that the homozygotes of CYP2B6*6 (Q172H and K262R) showed significantly (P<0.05) higher clearance and shorter half-life of cyclophosphamide than heterozygotes and homozygotes of CYP2B6*1. The small sample size, however, limited the impact. On the other hand, it was clearly demonstrated that the patients possessing the single nucleotide polymorphisms of the CYP2B6 gene, g.-2320T>C, g.-750T>C (5'-flanking region), g.15582C>T (intron 3), or g.18492T>C (intron 5), had significantly lower area under the curve ratios of 4-hydroxycyclophosphamide/cyclophosphamide, indicating a decreased cyclophosphamide 4-hydroxylation. Of particular importance was the finding that leukocytopenia was significantly related to the single nucleotide polymorphisms g.-2320T>C, g.-750T>C, and g.18492T>C in CYP2B6 gene, which are highly linked. No relationship was observed between the pharmacokinetics of cyclophosphamide or 4-hydroxycyclophosphamide and genetic polymorphisms of the other enzymes.

CONCLUSIONS

We clarified that the single nucleotide polymorphisms in the promoter region or introns in the CYP2B6 affect the potency of cyclophosphamide activation to 4-hydroxycyclophosphamide. This information would be valuable for predicting adverse reactions and the clinical efficacy of cyclophosphamide.

Thyroid function in paediatric and young adult patients after sarcoma therapy: a report from the Late Effects Surveillance System

OBJECTIVE

The role of chemotherapy in thyroid sequelae after cancer treatment has not been studied systematically, especially in sarcoma patients. The aim of this study was to determine the incidence of post-therapeutic thyroid disorders and their contributing factors in a cohort of paediatric sarcoma patients.

DESIGN

Late effects of sarcoma treatment have been collected prospectively within the Late Effects Surveillance System (LESS) in Germany, Austria and Switzerland since 1998.

PATIENTS

We studied 340 relapse-free paediatric patients (median age at diagnosis 12.2 [interquartile range (IQR) = 7.3-15.6 years] treated for osteosarcoma, soft tissue sarcoma or Ewing's sarcoma within the COSS-96, CWS-96/CWS-2002P or EICESS-92/EURO-E.W.I.N.G.-99 therapy trials. In addition to polychemotherapy, 127 patients were irradiated (mean cumulative dose 47 +/- 9.7 Gy), including 51 patients with irradiation to the head/neck region. Median follow-up was 24.6 (IQR = 11.9-44.9) months.

MEASUREMENTS

We reviewed the results of yearly examinations of serum TSH and fT4 levels and thyroid ultrasound examinations.

RESULTS

The incidence of thyroid disorders was 37% (19/51, 95% CI 24-52%) in patients with head/neck irradiation, and 11% (32/289, 95% CI 8-15%) in patients without irradiation to the head/neck. Thyroid disorders were more frequent in patients treated with idarubicin (P = 0.027) and trofosfamide (P = 0.016). We also found a significant association between raised TSH levels and treatment with trofosfamide (P = 0.008) or idarubicin (P = 0.037) (n = 250).

CONCLUSIONS

The incidence of thyroid disorders in the head/neck-irradiated group was high. Even without head/neck irradiation, we found an increased proportion of patients with thyroid disorders, possibly as a result of chemotherapy.

ANCA-associated vasculitis: new options beyond steroids and cytotoxic drugs

Small vessel vasculitic syndromes--Wegener's granulomatosis, microscopic polyangiitis and renal limited vasculitis (which are associated with circulating antineutrophil cytoplasmic autoantibodies)--are an important cause of renal failure. Present immunosuppressive regimens that are based on cyclophosphamide have significantly increased survival rates. However, these treatments are toxic, increase the risk of infection and do not cure disease. Therefore, newer approaches are required. Understanding disease pathogenesis has allowed rational use for newer therapies such as rituximab, which depletes B cells. Unfortunately, blockade of promising targets such as TNF-alpha, which was thought to be a pivotal cytokine in inflammation, has not shown benefit in a randomised controlled trial. Better understanding of the pathogenesis of the disease is the key to the development of novel targeted therapies, which are urgently required to improve patient prognosis. Gene therapy with targeted delivery of specific proteins is an exciting future prospect.

Simultaneous quantification of cyclophosphamide and its active metabolite 4-hydroxycyclophosphamide in human plasma by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS)

Cyclophosphamide is a cytotoxic prodrug with a very narrow therapeutic index. To study the clinical pharmacology of cyclophosphamide in a large cohort of patients a previously published method for the simultaneous quantitative determination of cyclophosphamide and 4-hydroxycyclophosphamide in human plasma using liquid chromatography tandem mass spectrometry (LC-MS/MS) was optimized. Addition of an isotopically labelled internal standard and adaptation of the gradient resulted in a fast, robust and sensitive assay. Because 4-hydroxycyclophosphamide is not stable in plasma, the compound is derivatized with semicarbazide immediately after sample collection. Sample preparation was carried out by protein precipitation with methanol-acetonitrile (1:1, v/v), containing isotopically labelled cyclophosphamide and hexamethylphosphoramide as internal standards. The LC separation was performed on a Zorbax Extend C18 column (150 mm x 2.1 mm ID, particle size 5 microm) with 1 mM ammonium hydroxide in water-acetonitrile (90:10, v/v) as the starting gradient, at a flow-rate of 0.40 mL/min with a total run time of 6 min. The lower limit of quantification (LLQ, using a 100 microL sample volume) was 200 ng/mL and the linear dynamic range extended to 40,000 ng/mL for cyclophosphamide and 50-5000 ng/mL for 4-hydroxycyclophosphamide. Accuracies as well as precisions were lower than 20% at the LLQ concentration and lower than 15% for all other concentrations. This method has been successfully applied in our institute to support ongoing studies into the pharmacokinetics and pharmacogenetics of cyclophosphamide.

Recurrent Low- to Intermediate-Grade Chondrosarcoma of the Thumb with Lung Metastases: An Objective Response to Trofosfamide

BACKGROUND

Low- to intermediate-grade chondrosarcoma is usually a slow-growing and highly chemotherapyresistant tumor type.

CASE REPORT

The 76-year-old female patient presented with low- to intermediate-grade chondrosarcoma of the distal phalanx of the right thumb in 1993 and was treated with an excision of the carpometacarpal joint. Approximately 10 years later, the patient presented with recurrent local disease at the trapezoid bone, which was resected. Eight months later she presented with local recurrence at the carpal joint and lung metastases. Subsequently she was treated chemotherapeutically with pegylated liposomal doxorubicin as part of a clinical trial. Due to tumor progression after 2 cycles, she was switched to oral trofosfamide (150 mg daily). A follow-up CT scan after 8 months demonstrated a partial remission that was confirmed by a second scan after 9 months of treatment. The treatment was well tolerated. After 18 months of continued treatment, she was still in remission and on trofosfamide.

CONCLUSION

Trofosfamide at a daily dose of 150 mg may be effective in low- to intermediate-grade chondrosarcoma.

Cytotoxic effects of histone deacetylase inhibitor FK228 (depsipeptide, formally named FR901228) in combination with conventional anti-leukemia/lymphoma agents against human leukemia/lymphoma cell lines

FK228 is a novel antitumor depsipeptide that inhibits histone deacetylases and restores the expression of genes aberrantly suppressed in cancer cells. This agent was shown to have broad antitumor activity in preclinical studies, and is currently under phase I/II evaluations. Because of its wide spectrum of actions, it is reasonable to consider the combination with other anticancer drugs in clinical application. We studied the cytotoxic interaction of FK228 in combination with conventional antileukemic agents using human promyelocytic leukemia HL60, Philadelphia chromosome-positive (Ph(+)) chronic myelogenous leukemia KU-812, T-cell lymphoblastic leukemia MOLT3 and Burkitt's lymphoma Raji cell lines. For the combination of FK228 and imatinib, Ph(+) leukemia KU812, K562 and TCC-S cell lines were used. The cells were exposed simultaneously to FK228 and other agents for 4 days. Cell growth inhibition was determined by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. We used the isobologram method of Steel and Peckham to evaluate the cytotoxic interaction at the concentration of drugs that produced 80% cell growth inhibition (IC(80)). FK228 showed an additive effect with cytarabine, carboplatin, doxorubicin, etoposide, 4-hydroperoxy-cyclophosphamide, 6-mercaptopurine and SN-38 (active metabolite of irinotecan) in all cell lines studied. FK228 with methotrexate and vincristine showed an antagonistic effect in three and one of the four cell lines, respectively. FK228 was additive with imatinib in all three Ph(+) leukemia cells. Our findings suggest that FK228 is a promising candidate for combining with most anticancer agents except for methotrexate and vincristine, which produce suboptimal effects.

Complete remission of relapsing high-grade angiosarcoma with single-agent metronomic trofosfamide

A limited repertoire of chemotherapeutics is available for the therapy of metastasizing angiosarcoma. Moreover, response rates are typically low and outcomes are unfavorable. Metronomically, dosed oral chemotherapy provides a convenient treatment option and surprisingly high response rates have been published for small patient groups. We report on a case from our clinic, in which a complete response with oral trofosfamide was achieved in a patient suffering from relapsed high-grade angiosarcoma metastasizing to the liver and lung. The patient experienced minimal side-effects from her trofosfamide treatment. Responses like this are encouraging and should make us rethink treatment approaches for metastasizing soft-tissue sarcoma. The mechanism of action of metronomic chemotherapy, although thought to be antiangiogenic in nature, is still unclear, as is the additive effect of angiogenic inhibitors like cyclooxygenase II inhibitors or peroxisome proliferator-activated receptor-gamma agonists. Prospective studies that include the examination of patient samples during treatment are ongoing in order to optimize further development of this novel therapeutic approach.

Real-time dose adjustment of cyclophosphamide in a preparative regimen for hematopoietic cell transplant: a Bayesian pharmacokinetic approach

PURPOSE

Dose-related toxicity of cyclophosphamide may be reduced and therapeutic efficacy may be improved by pharmacokinetic sampling and dose adjustment to achieve a target area under the curve (AUC) for two of its metabolites, hydroxycyclophosphamide (HCY) and carboxyethylphosphoramide mustard (CEPM). To facilitate real-time dose adjustment, we developed open-source code within the statistical software R that incorporates individual data into a population pharmacokinetic model.

EXPERIMENTAL DESIGN

Dosage prediction performance was compared to that obtained with nonlinear mixed-effects modeling using NONMEM in 20 cancer patients receiving cyclophosphamide. Bayesian estimation of individual pharmacokinetic parameters was accomplished from limited (i.e., five samples over 0-16 hours) sampling of plasma HCY and CEPM after the initial cyclophosphamide dose. Conditional on individual pharmacokinetics, simulations of the AUC of both HCY and CEPM were provided for a range of second doses (i.e., 0-100 mg/kg cyclophosphamide).

RESULTS

The results compared favorably with NONMEM and returned accurate predictions for AUCs of HCY and CEPM with comparable mean absolute prediction error and root mean square prediction error. With our method, the mean absolute prediction error and root mean square prediction error of AUC CEPM were 11.0% and 12.8% and AUC HCY were 31.7% and 44.8%, respectively.

CONCLUSIONS

We developed dose adjustment software that potentially can be used to adjust cyclophosphamide dosing in a clinical setting, thus expanding the opportunity for pharmacokinetic individualization of cyclophosphamide. The software is simple to use (requiring no programming experience), reads individual patient data directly from an Excel spreadsheet, and runs in less than 5 minutes on a desktop PC.

In vitro sensitivity of B-cell chronic lymphocytic leukemia to cladribine and its combinations with mafosfamide and/or mitoxantrone

We examined in vitro sensitivity of B-CLL cells exposed to cladribine, mafosfamide, mitoxantrone and combinations ofcladribine with mafosfamide and/or mitoxantrone. The results revealed that each applied treatment of leukemic cells, besides having a cytotoxic effect, affected the events associated with apoptosis. All drugs used alone, and cladribine combinations with mafosfamide and/or mitoxantrone induced DNA fragmentation and the changes in expression/proteolysis level of caspase-3, caspase-9 precursors, PARP-1, lamin B, Bax and Bcl-2; however, each to a different degree. The exposure of leukemic cells to both cladribine combinations induced stronger effects. Moreover, the data showed that the expression of regulatory antiapoptotic protein Bcl-2 generally decreased in drug-treated B-CLL cells, whereas proapoptotic polypeptide Bax increased, resulting in enhancement of Bax-Bcl-2 ratios in comparison with untreated cells. Drug-treatment of the studied cells induced the translocation of Bax protein from the cytosol to the cellular pellet, containing mitochondria, where this polypeptide indicated the capacity for oligomerization. These observations suggest that the examined drugs are able to induce apoptosis of B-CLL cells via the mitochondria pathway.

New agents for intrathecal administration

Intrathecal administration of chemotherapy, with or without radiation therapy, is the primary treatment modality for the prevention and treatment of central nervous system (CNS) metastases in patients with leukemia or lymphoma. Although this treatment strategy has been very effective for patients with hematological malignancies, currently available intrathecal agents are relatively ineffective for patients with neoplastic meningitis resulting from an underlying solid or CNS tumor effective. This article provides an overview of some of the practical considerations and limitations associated with intrathecal chemotherapy, and is followed by a comprehensive review of some of the preclinical and early phase clinical trials of novel anticancer agents and treatment strategies using the intrathecal route.

Chemotherapy disrupts activity of translational regulatory proteins in bone marrow stromal cells

OBJECTIVE

Bone marrow stromal cell function is a critical influence on hematopoietic reconstitution following progenitor or stem cell transplantation. Stromal cells support hematopoietic cell migration, survival, and proliferation. We have previously reported that stromal cell matrix metalloproteinase-2 (MMP-2) is necessary for optimal support of pro-B-cell chemotaxis through its regulation of stromal cell-derived factor-1 (CXCL12) release. Following exposure to the topoisomerase II inhibitor, etoposide (VP-16), stromal cell MMP-2 protein expression is reduced. The current study investigated the mechanism by which VP-16 may alter translation of MMP-2 in bone marrow stromal cells.

MATERIALS AND METHODS

Bone marrow stromal cells were exposed to chemotherapeutic agents etoposide, melphalan, and 4-hydroperoxycyclophosphamide (4HC) and evaluated for MMP-2 expression by enzyme-linked immunosorbent assay and support of pro-B-cell chemotaxis by chemotaxis assay. Western blot analyses were completed to evaluate phosphorylation of stromal cell translational regulatory proteins 4E binding protein-1 (4EBP-1), P70(S6K), and S6 or MMP-2 in the presence of chemotherapy, or the chemical inhibitors rapamycin or LY294002.

RESULTS

Rapid dephosphorylation of 4EBP-1, P70(S6K), and S6 following VP-16 exposure was observed, consistent with blunted translational efficiency. We also observed that inhibition of stromal cell mammalian target of rapamycin with rapamycin, or phosphatidylinositol 3 kinase with LY294002, resulted in inhibition of stromal cell MMP-2 protein. In addition we found that the chemotherapeutic agents melphalan and 4HC disrupt bone marrow stromal cell MMP-2 protein expression and support of chemotaxis.

CONCLUSIONS

These data suggest that one mechanism by which chemotherapy may alter stromal cells of the bone marrow microenvironment is through disrupted translation of proteins.

Teratogen-Induced Activation of p53 in Early Postimplantation Mouse Embryos

Hyperthermia (HS) and 4-hydroperoxycyclophosphamide (4CP) activate the mitochondrial apoptotic pathway in day 9 mouse embryos. Previous microarray analyses Microarray analyses revealed that several p53 target genes are upregulated after exposure to HS or 4CP, suggesting a role for p53 in teratogen-induced apoptosis. To explore the role of p53, we assessed the activation of p53 in day 9 mouse embryos exposed to HS or 4CP in vitro. Both teratogens induced the accumulation of p53 and phosphorylation of p53 at ser-15, two hallmarks of p53 activation. HS and 4CP also induced an increase in Noxa and Puma mRNAs, transcripts of two known proapoptotic p53 target genes; however, these two teratogens did not induce significant increases in NOXA and PUMA proteins, suggesting that p53 does not activate the mitochondrial apoptotic pathway by transcriptionally upregulating the expression of NOXA and PUMA proteins. HS and 4CP also induced the expression of p21 mRNA and protein, suggesting a role for p53 in teratogen-induced cell cycle arrest. Previously, we also showed that HS and 4CP activate the apoptotic pathway in the embryo proper (head and trunk) but not in the heart. We now show that HS and 4CP induce a robust activation of p53 in the embryo proper but an attenuated induction in the heart. HS and 4CP induce the expression of p21 protein in majority of the cells in the embryo; however, expression of NOXA and PUMA proteins were not significantly induced in heads, hearts, or trunks of day 9 embryos. Overall, our results suggest that p53 may play a transcription-dependent role in teratogen-induced cell cycle arrest but a transcription-independent role in teratogen-induced apoptosis in day 9 mouse embryos exposed to HS or 4CP.

Ex vivo expansion of mafosfamide-purged PBPC products

BACKGROUND

Multiple studies have demonstrated that 'purging' of autografts with 4-hydroperoxycyclophosphamide (4HC) or the related compound mafosfamide (Mf), to eradicate residual leukemia, produces the best results associated with autologous blood and marrow transplantation for AML. However, 4HC purging results in prolonged aplasia. Therefore, we evaluated the potential of ex vivo expansion of Mf-treated CD34+ cells from mobilized PBPC.

METHODS

CD34+ cells were isolated from PBPC products and treated with 30 microg/mL Mf. The Mf-treated CD34+ cells were washed and cultured for 14 days in StemLine II-defined media containing recombinant human (rh) SCF, G-CSF and thrombopoietin (Tpo).

RESULTS

Treatment with Mf resulted in 90% killing of progenitor cells (GM-CFC) but maintenance of SCID-repopulating cells (SRC). Ex vivo culture of the Mf-treated CD34+ cells resulted in decreased cell numbers (10-20% of the starting cell dose) during the first week. Nevertheless, in the second week of culture the total cell numbers expanded to approximately 20-fold above starting cell numbers and progenitor cells returned to approximately pre-treatment levels.

DISCUSSION

These studies demonstrate the potential of ex vivo culture to expand both total cell numbers and progenitor cells following treatment of PBPC CD34+ cells with Mf. Clinical studies are currently being initiated to evaluate the engraftment potential of these purged and expanded products.

Secondary dissemination in children with high-grade malignant gliomas and diffuse intrinsic pontine gliomas

In children, treatment regimen for high-grade gliomas (HGG) and diffuse intrinsic pontine gliomas (DIPG) are generally not stratified according to disease stage. The hypothesis was that secondary disseminating disease (SDD) in children with HGG is related to an even worse outcome. Description of SDD pattern was performed. In total, 270 children with newly diagnosed HGG or DIPG were eligible for retrospective analysis of SDD. Medical and computer records of these patients were reviewed for demographic characteristics, sites of dissemination, prognostic variables. Forty-six (17%) of the 270 patients had developed SDD. The median time to SDD was 8.2 months. The median overall survival (OS) after dissemination was 3.2 months. The SDD was located parenchymal in the supratentorial (34.8%), infratentorial (6.5%), supratentorial and infratentorial (19.6%), spinal (10.9%), spinal and cerebral (6.5%) regions of the CNS, or leptomeningeal (21.7%). For HGG patients, the median OS was shorter among patients with SDD than among patients without SDD (1.02 vs 1.41 years, P=0.0495). In the group of patients with SDD, patients with cerebrospinal fluid dissemination had a worse outcome compared with patients with parenchymal metastases. Summarising, SDD is a negative prognostic factor for patients with HGG outside the pons. Treatment stratification should be considered.

Xrcc2 deficiency sensitizes cells to apoptosis by MNNG and the alkylating anticancer drugs temozolomide, fotemustine and mafosfamide

DNA double-strand breaks (DSBs) are potent killing lesions, and inefficient repair of DSBs does not only lead to cell death but also to genomic instability and tumorigenesis. DSBs are repaired by non-homologous end-joining and homologous recombination (HR). A key player in HR is Xrcc2, a Rad51-like protein. Cells deficient in Xrcc2 are hypersensitive to X-rays and mitomycin C and display increased chromosomal aberration frequencies. In order to elucidate the role of Xrcc2 in resistance to anticancer drugs, we compared Xrcc2 knockout (Xrcc2-/-) mouse embryonic fibroblasts with the corresponding isogenic wild-type and Xrcc2 complemented knockout cells. We show that Xrcc2-/- cells are hypersensitive to the killing effect of the simple methylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). They undergo apoptosis after MNNG treatment while necrosis is only marginally enhanced. Complementation of Xrcc2 deficient cells by Xrcc2 cDNA transfection conferred resistance to the cytotoxic and apoptosis-inducing effect of MNNG. The hypersensitivity of Xrcc2-/- cells to MNNG prompted us to investigate their killing and apoptotic response to various methylating, chloroethylating and crosslinking drugs used in anticancer therapy. Xrcc2 deficient cells were found to be hypersensitive to temozolomide, fotemustine and mafosfamide. They were also hypersensitive to cisplatin but not to taxol. The data reveal that Xrcc2 plays a role in the protection against a wide range of anticancer drugs and, therefore, suggest Xrcc2 to be a determinant of anticancer drug resistance. They also indicate that HR is involved in the processing of DNA damage induced by simple alkylating agents.

Novel gene-directed enzyme prodrug therapies against prostate cancer

There is no effective cure for late-stage hormone (androgen) refractory prostate cancer. Although chemotherapy offers palliation to these late-stage patients, it also leads to systemic toxicities leading to poor quality of life. Clearly, the focus is on the development and evaluation of novel biologically relevant alternatives such as cytoreductive gene-directed enzyme prodrug therapy (GDEPT). With the current limitations of effective gene delivery in vivo, the in situ amplification of cytotoxicity due to bystander effects of GDEPT has special attraction for patients with prostate cancer, the prostate being dispensable. This review focuses on the development, application and potential of various GDEPTs for treating prostate cancer. The current status of research related to the issues of enhancement of in situ GDEPT delivery and prostate cancer-specific targeting of vectors (especially viral vectors) is assessed. Finally, the scope and progress of synergies between GDEPT and other treatment modalities, both traditional and alternate, are discussed.

Novel class of cyclophosphamide prodrug: Cyclophosphamide spiropiperaziniums (CPSP)

A novel class of cyclophosphamide spiropiperaziniums was synthesized and evaluated for their in vivo anti-cancer activities against S180 and H22. Most of them exhibited definite activities. Especially, compounds 8b and 8k showed good anti-cancer activities, meanwhile, 8k also showed much lower toxicity than CP. Several interesting structure-activity relationships were revealed.