Synergistic cytotoxicity of different alkylating agents for epithelial ovarian cancer

Alkylating agents have been used individually and in combination to treat epithelial ovarian carcinoma. In this study, the cytotoxicity of 7 alkylating agents has been measured using a serial dilution clonogenic assay. When individual agents were evaluated, markedly different activity was observed against several ovarian cancer cell lines. Among 4 cell lines tested, OVCA 432 was the most sensitive to cisplatin, thiotepa and melphalan. When alkylating agents were used in combination against OVCA 432, synergistic activity was observed with cisplatin and each of several other alkylating agents including thiotepa, melphalan, 4-hydroperoxycyclophosphamide (4HC) and carboplatin. The combination of cisplatin and thiotepa also exerted synergistic activity against the OVCA 420, 429 and 433 cell lines, but had only additive or subadditive activity against the NIH:OVCAR-3 cell line. Sequential treatment of tumor cell lines with the different alkylating agents was as effective as simultaneous treatment. Synergistic anti-tumor activity in cell culture is consistent with clinical observations that alkylating agents in combination appear more effective than single agents for treatment of advanced epithelial ovarian cancer. In addition, our study suggests that cisplatin in combination with thiotepa, 4HC or melphalan might prove useful for high-dose therapy with autologous bone-marrow support.     

High-dose combination alkylating agents with bone marrow support as initial treatment for metastatic breast cancer

To evaluate the effect of high-dose chemotherapy in the treatment of metastatic breast cancer, we performed a phase II trial of a single treatment with high-dose cyclophosphamide (5,625 mg/m2), cisplatin (165 mg/m2), and carmustine (600 mg/m2), or melphalan (40 mg/m2) and bone marrow support as the initial chemotherapy for metastatic breast cancer. Twenty-two premenopausal patients with estrogen receptor negative, measurable metastatic disease were treated. Twelve of 22 patients (54%) obtained a complete response at a median 18 days. The overall response rate is 73% (complete and partial response). Median duration of response in the patients achieving complete response was 9.0 months with a median duration of survival for complete responders that is currently undefined. Relapse occurred predominantly at sites of pretreatment bulk disease or within areas of previous radiation therapy. Toxicity was frequent and five patients died of therapy-related complications. The results indicate that a single treatment with intensive combination alkylating agents with bone marrow support can produce more rapid and frequent complete responses than conventional chemotherapy when used as initial chemotherapy for metastatic breast cancer, although median disease-free and overall survival is not improved. Three patients (14%) remain in unmaintained remission beyond 16 months.     

Cholelithiasis after treatment for childhood cancer

The authors evaluated the risk of development of cholelithiasis in 6050 patients treated at a single hospital for various childhood cancers with different therapeutic modalities, including chemotherapy, surgery, radiation therapy, and bone marrow transplantation, from 1963 to 1989. Patients with underlying chronic hemolytic anemia or preexisting gallstones were excluded. Nine female and seven male patients with a median age of 12.4 years (range, 1.2 to 22.8 years) at diagnosis of primary cancer had gallstones develop 3 months to 17.3 years (median, 3.1 years) after therapy was initiated. Cumulative risks of 0.42% at 10 years and 1.03% at 18 years after diagnosis substantially exceed those reported for the general population of this age group. Treatment-related factors significantly associated with an increased risk of cholelithiasis were ileal conduit, parenteral nutrition, abdominal surgery, and abdominal radiation therapy (relative risks and 95% confidence intervals = 61.6 [27.9-135.9], 23.0 [9.8-54.1], 15.1 [7.1-32.2], and 7.4 [3.2-17.0], respectively). There was no correlation with the type of cancer, nor was the frequency of conventional predisposing features (e.g., family history, obesity, use of oral contraceptives, and pregnancy) any higher among the affected patients in this study than in the general population. Patients with cancer who have risk factors identified here should be monitored for the development of gallstones.     

Chemosensitization by monofunctional alkylating agents

The chemosensitizing ability of model monofunctional alkylating agents with known DNA base alkylating characteristics, that is, methylmethanesulphonate (MMS), ethyl methanesulphonate (EMS) and N-methyl-N-nitrosoguanidine (MNNG) have been investigated. Whereas the alkyl sulphonates chemosensitize V79 cells to cisplatin and melphalan, MNNG does not. The dose response curves show shoulder removal. Drug scheduling and thiourea post-treatment experiments indicate that the effect is likely to be on the initial alkylation rather than completion of crosslink formation from an initial adduct.     

New soft alkylating agents with enhanced cytotoxicity against cancer cells resistant to chemotherapeutics and hypoxia

Chloroethylureas (CEU) are soft alkylating agents that covalently bind to beta-tubulin (betaTAC) and affect microtubule polymerization dynamics. Herein, we report the identification of a CEU subset and its corresponding oxazolines, which induce cell growth inhibition, apoptosis, and microtubule disruption without alkylating beta-tubulin (N-betaTAC). Both betaTAC and N-betaTAC trigger the collapse of mitochondrial potential (DeltaPsi(m)) and modulate reactive oxygen species levels, following activation of intrinsic caspase-8 and caspase-9. Experiments using human fibrosarcoma HT1080 respiratory-deficient cells (rho(0)) and uncoupler of the mitochondrial respiratory chain (MRC) showed that betaTAC and N-betaTAC impaired the MRC. rho(0) cells displayed an increased sensitivity toward N-betaTAC as compared with rho(+) cells but, in contrast, were resistant to betaTAC or classic chemotherapeutics, such as paclitaxel. Oxazoline-195 (OXA-195), an N-betaTAC derivative, triggered massive swelling of isolated mitochondria. This effect was insensitive to cyclosporin A and to Bcl-2 addition. In contrast, adenine nucleotide translocator (ANT) antagonists, bongkrekic acid or atractyloside, diminished swelling induced by OXA-195. The antiproliferative activities of the N-betaTACs CEU-025 and OXA-152 were markedly decreased in the presence of atractyloside. Conversely, pretreatment with cyclosporin A enhanced growth inhibition induced by betaTAC and N-betaTAC. One of the proteins alkylated by N-betaTAC was identified as the voltage-dependent anion channel isoform-1, an ANT partner. Our results suggest that betaTAC and N-betaTAC, despite their common ability to affect the microtubule network, trigger different cytotoxic mechanisms in cancer cells. The role of mitochondria in these mechanisms and the potential of N-betaTAC as a new therapeutic approach for targeting hypoxia-resistant cells are discussed.     

Retinoid therapy of childhood cancer

In vitro studies that showed RA could cause growth arrest and differentiation of myelogenous leukemia and neuroblastoma led to clinical trials of retinoids in APL and neuroblastoma that increased survival for both of those diseases. In the case of APL, ATRA has been the drug of choice, and preclinical and clinical data support direct combinations of ATRA with cytotoxic chemotherapy. For neuroblastoma, a phase I study defined a dose of 13-cis-RA, which was tolerable in patients after myeloablative therapy, and a phase III trial that showed postconsolidation therapy with 13-cis-RA improved EFS for patients with high-risk neuroblastoma. Preclinical studies in neuroblastoma indicate that ATRA or 13-cis-RA can antagonize cytotoxic chemotherapy and radiation, so use of 13-cis-RA in neuroblastoma is limited to maintenance after completion of cytotoxic chemotherapy and radiation. A limitation on the antitumor benefit of ATRA in APL is the marked decrease in drug levels that occurs during therapy as a result of induction of drug metabolism, resulting in a shorter drug half-life and decreased plasma levels. Although early studies sought to overcome the pharmacologic limitations of ATRA therapy in APL, the demonstration that ATO is active against APL in RA-refractory patients has led to a focus on studies employing ATO. Use of 13-cis-RA in neuroblastoma has avoided the decreased plasma levels seen with ATRA. It is likely that recurrent disease seen during or after 13-cis-RA therapy in neuroblastoma is due to tumor cell resistance to retinoid-mediated differentiation induction. Studies in neuroblastoma cell lines resistant to 13-cis-RA and ATRA have shown that they can be sensitive, and in some cases collaterally hypersensitive, to the cytotoxic retinoid fenretinide. Fenretinide induces tumor cell cytotoxicity rather than differentiation, acts independently from RA receptors, and in initial phase I trials has been well tolerated. Clinical trials of fenretinide, alone and in combination with ceramide modulators, are in development.     

Rationale for combination therapy of chronic myelogenous leukaemia with imatinib and irradiation or alkylating agents: implications for pretransplant conditioning

The tyrosine kinase activity of the BCR-ABL oncoprotein results in reduced apoptosis and thus prolongs survival of chronic myelogenous leukaemia cells. The tyrosine kinase inhibitor imatinib (formerly STI571) was reported to selectively suppress the proliferation of BCR-ABL-positive cells. Assuming that imatinib could be included in pretransplantation conditioning therapies, we tested whether combinations of imatinib and gamma-irradiation or alkylating agents such as busulfan or treosulfan would display synergistic activity in BCR-ABL-positive chronic myelogenous leukaemia BV173 and EM-3 cell lines. Further, primary cells of untreated chronic myelogenous leukaemia patients were assayed for colony forming ability under combination therapy with imatinib. Additionally, the cytotoxic effect of these combinations on BCR-ABL-negative cells was investigated. In the cell lines a tetrazolium based MTT assay was used to quantify growth inhibition after exposure to cytotoxic drugs alone or to combinations with imatinib. Irradiation was applied prior to exposure to imatinib. Interaction of drugs was analysed using the median-effect method of Chou and Talalay. The combination index was calculated according to the classic isobologram equation. The combination imatinib + gamma-irradiation proved to be significantly synergistic over a broad range of cell growth inhibition levels in both BCR-ABL-positive cell lines and produced the strongest reduction in primary chronic myelogenous leukaemia colony-forming progenitor cells. Combinations of imatinib + busulfan and imatinib + treosulfan showed merely additive to antagonistic effects. Imatinib did not potentiate the effects of irradiation or cytotoxic agents in BCR-ABL-negative cells. Our data provide the basis to further develop imatinib-containing conditioning therapies for stem cell transplantation in chronic myelogenous leukaemia.     

Nasopharyngeal lymphoid hyperplasia after therapy for childhood lymphomas

Although diffuse thymic hyperplasia after therapy has been reported in lymphomas, no report is found in the medical literature about hyperplasia of other lymphoid tissues following chemotherapy in malignancies as far as we could reach. So, we planned to investigate the nasopharyngeal region of the lymphoma cases during their follow-up while at remission. Children who were in follow-up after cessation of oncological therapy with the diagnosis of lymphoma were evaluated for their nasopharyngeal lymphoid tissues by means of computed tomography. When a mass lesion was diagnosed, biopsies were taken. Among 23 lymphoma cases in follow-up, at a median of eight months (range 1-13 months), eight patients (six Hodgkin's and two Non-Hodgkin's malignant lymphoma) developed nasopharyngeal lymphoid hyperplasia (34.78%) that were proven to be benign by means of biopsies. Two of the patients also developed thymic hyperplasia. Nasopharyngeal hyperplasia regressed in four patients at a median of four months. Nasopharyngeal lymphoid hyperplasia may be diagnosed after the cessation of therapy in lymphomas and whatever the cause, it seems to be a benign process.     

Adriamycin plus alkylating agents in the treatment of metastatic breast cancer.

A randomized trial of Adriamycin (A) in combination with melphalan (M), (MA therapy), and in combination with M plus cyclophosphamide (C) (MAC therapy), was initiated in 40 evaluable patients with metastatic breast cancer. Twenty-two patients demonstrated an objective response to therapy: 9/20 to the MA regimen, and 13/20 to the MAC regimen. For the 22 responders, median duration of response is not yet achieved for either complete or partial responders, at 10 and 9 months, respectively. The addition of the two alkylating agents to Adriamycin was superior to the single alkylating agent addition, both in total response rate and in completeness of response. Maintenance therapy, after achieving the maximum cumulative dose of Adriamycin, was provided by cyclophosphamide plus methotrexate and 5-fluorouracil (CMF). In 19 patients completing induction and entering maintenance therapy, only one relapse has developed with maximun follow-up at 15 months.     

Delivery of antiangiogenic agents for cancer gene therapy

The understanding that tumor growth and metastasis are angiogenesis dependent processes has led to interest in targeting tumor vasculature in anticancer therapy. Furthermore, recent insights into the molecular interactions that orchestrate physiologic and pathologic angiogenesis have resulted in a variety of antiangiogenic strategies. A gene therapy-mediated approach for the delivery of antiangiogenic agents has several advantages, including the potential for sustained expression. However, the choice of angiogenesis inhibitor, method of gene delivery, and target/site for transgene expression are important variables to be considered when designing this approach. Here we review the major alternatives within each of these categories and provide illustrative examples of their use in preclinical models.     

Targeted agents for adjuvant therapy of colon cancer

Among patients with colorectal cancer (CRC) diagnosed in the United States, 37.2% are diagnosed with stage III and 27.9% with stage II disease. In locoregionally advanced CRC, surgery is the primary treatment modality and has a curative intent. The survival depends on the pathologic stage and varies from 30%-60% for stage III to 60%-80% for stage II. However, as much as 40%-50% of patients will relapse and require additional treatment of the disease. Clinical failure after resection of CRC is predominantly secondary to the clinical progression of previously undetected distant metastatic disease. Until very recently, the absolute benefit for survival obtained with adjuvant therapy compared with control was about 6%. Introduction of oxaliplatin in the adjuvant setting has shown a reduction of 23% in the risk of relapse when compared with 5-fluorouracil alone (MOSAIC). Recent phase III studies have shown that targeted agents improved survival in patients with advanced-stage CRC. Bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor, is the first antiangiogenic drug to show improved efficacy when used in combination with irinotecan and oxaliplatin for first- and second-line treatment of CRC. Cetuximab, another monoclonal antibody targeting epidermal growth factor receptor, has shown efficacy in third-line therapy and promising results in first-line phase II studies. There is great interest in whether the biologic agents bevacizumab and cetuximab can improve survival in the adjuvant-therapy setting. This article reviews the adjuvant therapy for colon cancer and discusses the potential role and current trials involving the targeted agents.