Synergistic cytotoxic activity of treosulfan and gemcitabine in pancreatic cancer cell lines.

BACKGROUND: Treatment for advanced pancreatic cancer is still very unsatisfactory. Treosulfan is an alkylating agent used for conventional, as well as high-dose chemotherapy regimens, whereby plasma concentrations over 500 µg/ml can be achieved. We investigated the effects of treosulfan on pancreatic cancer cell lines. MATERIALS AND METHODS: Using Panc-1, MIA PaCa-2 and Capan-2 cell lines, we investigated the in vitro cytotoxicity of treosulfan-alone and in combination with gemcitabine, 5-fluorouracil or irradiation. RESULTS: Treosulfan was potently cytotoxic against all pancreatic cancer cell lines at all concentrations (1-100 µg/ml). Combination of treosulfan and gemcitabine revealed strong synergistic effects independent of the sequence of drug administration. Similarly, synergism was observed with irradiation. Combination of treosulfan and 5-fluorouracil revealed antagonism. CONCLUSION: Treosulfan effectively kills pancreatic carcinoma cells in vitro and has synergistic activity in combination with gemcitabine and irradiation. These results warrant further investigation of treosulfan in the treatment of pancreatic cancer.

Preclinical analysis of treosulfan in combination with total body irradiation as conditioning regimen prior to bone marrow transplantation in rats.

Treosulfan (Treo) and total body irradiation (TBI) demonstrate a high therapeutic activity in treatment of acute leukemia and lymphoma. We investigated the combination of Treo and TBI prior to bone marrow transplantation (BMT) in rats. Female Lewis rats were treated with Treo on 3 consecutive days followed by TBI with either 5 Gy (n = 28) or 7.5 Gy (n = 48). After conditioning animals received 4 x 10E7 bone marrow cells (BC) from female Lewis rats. Additional 16 rats were transplanted with 4 x 10E7 BC and 1.5 x 10E7 spleen T-cells from female Brown-Norway (BN) rats. Animals were examined daily for clinical signs and toxicity was investigated by necropsy and histology in all animals. Gastrointestinal toxicity was the dose-limiting factor of Treo in combination with TBI. The highest tolerable dose of Treo in combination with 7.5 Gy TBI was 3 x 0.5 g/kg and the highest tolerable dose of Treo in combination with 5 Gy TBI was 3 x 0.6 g/kg. Allogeneic BMT from BN donors resulted in engraftment and survival of 12 out of 16 animals. Gastrointestinal toxicity is the dose-limiting factor in the treatment with Treo and TBI. Furthermore, Treo possesses certain characteristics of a radiosensitizer.

Myeloablative and immunosuppressive properties of treosulfan in mice.

OBJECTIVE: Treosulfan is a prodrug with a specific clinical activity in ovarian carcinoma and other solid tumors. Due to its myeloablative and immunosuppressive effects, its use in conditioning regimens prior to allogeneic stem cell treatment (SCT) has been proposed. In the present preclinical study, myeloablative as well as immunosuppressive properties of treosulfan were compared with those of busulfan and cyclophosphamide. METHODS: Three groups of BALB/c mice were treated with treosulfan, cyclophosphamide, or busulfan at sublethal doses that maintained survival without bone marrow support. The control group was left untreated. At different intervals, colony-forming unit granulocyte macrophage assay was performed on marrow cells. Additionally, immunological analyses were performed using spleen cells. RESULTS: We found that treosulfan and busulfan induced a high and persisting degree of myeloablation, as compared with cyclophosphamide. Moreover, treosulfan was more effective in depletion of splenic B and T cells in comparison with busulfan and cyclophosphamide. Furthermore, T cells isolated from the spleens of treosulfan- or busulfan-treated mice were not responsive to allogeneic cells compared with that observed in controls and cyclophosphamide-treated mice. Treatment with treosulfan induced only interleukin-2 production in spleen cells for a short time and had no significant effect on synthesis of tumor necrosis factor-alpha and/or interferon-gamma as compared with that observed in splenic T cells isolated from mice treated with either busulfan or cyclophosphamide. CONCLUSION: Our findings suggest that treosulfan possesses both myeloablative and immunosuppressive properties and may be used as a single agent for conditioning prior to bone marrow transplantation.

A randomised comparison of treosulfan and carboplatin in patients with ovarian cancer: a study by the Scottish Gynaecological Cancer Trials Group (SGCTG).

The management of older and unfit women with advanced ovarian cancer requires post-operative chemotherapy but many of these patients are not suitable for high-dose cisplatin-based regimes. Carboplatin has been an easier alternative and can be given in the ambulatory setting. Historical data suggests that oral alkylating agents to be just effective with similar efficacy. In this study we have compared platinum-based carboplatin to the alkylating agent treosulfan in a population unfit to receive high-dose cisplatin. The trial randomised patients to either intravenous carboplatin or treosulfan as single agent. The trial was stopped prematurely after the interim analysis showed improved survival and response rates in the carboplatin arm. We conclude that carboplatin is a safe and effective drug in a population that is unfit for high-dose cisplatin. Treosulfan showed limited activity but may be considered along with other oral drugs in limited circumstances. With the exception of myelosuppression, toxicity was mild in both arms. Carboplatin remains the gold standard in this older and less fit group of patients.

In vitro evaluation of dimethane sulfonate analogues with potential alkylating activity and selective renal cell carcinoma cytotoxicity.

We identified five structurally related dimethane sulfonates with putative selective cytotoxicity in renal cancer cell lines. These compounds have a hydrophobic moiety linked to a predicted alkylating group. A COMPARE analysis with the National Cancer Institute Anticancer Drug Screen standard agent database found significant correlations between the IC50 of the test compounds and the IC50 of alkylating agents (e.g., r = 0.68, P < 0.00001 for chlorambucil). In this report, we examined whether these compounds had activities similar to those of conventional alkylating agents. In cytotoxicity studies, chlorambucil-resistant Walker rat carcinoma cells were 4- to 11-fold cross-resistant to the test compounds compared with 14-fold resistant to chlorambucil. To determine effects on cell cycle progression, renal cell carcinoma (RCC) line 109 was labeled with bromodeoxyuridine prior to drug treatment. Complete cell cycle arrest occurred in cells treated with an IC90 dose of NSC 268965. p53 protein levels increased as much as 5.7-fold in RCC line 109 and as much as 20.4-fold in breast cancer line MCF-7 following an 18-hour drug exposure. Finally, DNA-protein cross-links were found following a 6-hour pretreatment with all compounds. Thus, the dimethane sulfonate analogues have properties expected of some alkylating agents but, unlike conventional alkylating agents, appear to possess activity against RCC.

Towards a myeloablative regimen with clinical potential: I. Treosulfan conditioning and bone marrow transplantation allow induction of donor-specific tolerance for skin grafts across full MHC barriers.

To investigate whether we could create a radiation-free conditioning regimen to induce permanent mixed and multilineage chimerism and donor-specific tolerance, we treated recipient mice with anti-T-cell antibodies, varying and fractionated doses of Treosulfan and fully MHC disparate bone marrow cells. Treosulfan is mainly used in the treatment of ovarian cancer. It is a structural analog of busulfan, but it does not induce severe hepatotoxicity or veno-occlusive disease at or above the maximum tolerated dose, lacks significant nonhematological toxicity and has limited organ toxicity. We report here the successful induction of permanent mixed multilineage chimerism and donor-specific tolerance as was proven by skin transplantation and IFN-gamma ELISPOT. In conclusion, because of its lower nonhematological toxicity, compared with other myeloablative regimens (eg irradiation or busulfan admin- istration), Treosulfan could be a better candidate for conditioning to induce donor-specific allograft tolerance.

Antileukaemic activity of treosulfan in xenografted human acute lymphoblastic leukaemias (ALL).

Treosulfan (L-threitol-1,4-bis-methanesulphonate; Ovastat(R)) is a bifunctional alkylating drug indicated for the treatment of advanced ovarian carcinoma. Recent data revealed immunosuppressive characteristics and substantial haematopoietic stem cell toxicity after repeated dosing of mice. Therefore, treosulfan is considered to be an alternative conditioning agent to busulfan (for example) administered prior to allogeneic/autologous stem cell transplantation of patients with haematological malignancies. An antineoplastic activity for treosulfan has been previously shown in preclinical models of melanoma, breast, lung and renal-cell carcinomas. Here, in vivo antileukaemic activity of treosulfan is compared with the activity of equitoxic doses of cyclophosphamide or busulfan for the first time using human acute lymphoblastic leukaemia (ALL)-models of paediatric origin xenotransplanted into non-obese diabetic (NOD)/severe combined immunodeficient (SCID) mice. Treosulfan treatment achieved an optimum treated to control (T/C) value of 159% (survival time) against B-ALL-SCID 7 and a T/C value of 0% (tumour growth) against T-ALL-SCID 4 and proB-ALL-SCID 19, respectively. Complete regression of established subcutaneously (s.c.) growing nodules of ALL-SCID 4 and 19 was obvious and long-term survivors without tumour re-growth were observed. Equitoxic doses of busulfan (ALL-SCID 4, 7, 19) or cyclophosphamide (ALL-SCID 19) were less effective with regard to the numbers of complete regressions and the number of cured animals. Side-effects included myelotoxicity and a small reduction in body weight, but these were tolerable. Treosulfan can be considered a highly active antileukaemic drug whose corresponding clinical value is to be tested in appropriate protocols with leukaemic patients.

Antitumor activity of treosulfan against human breast carcinomas.

Treosulfan (L-threitol-1,4-bismethanesulfonate, Ovastat) is a bifunctional alkylating agent that shows a formal structural similarity to busulfan and is applied clinically to patients suffering from ovarian cancer. The present study demonstrated the pronounced antitumor activity of this drug against three of five human breast carcinomas xenografted to athymic mice. It was shown that treosulfan is capable of inducing irreversible and complete remission of the heterotransplanted human breast carcinomas MDA-MB-436 and MX-1 within 14 days after drug application and of effecting growth inhibition by more than 90% in the MDA-MB-435S xenograft. In all three carcinomas, treosulfan caused more pronounced growth reduction than did equitoxic doses of the alkylator cyclophosphamide. Adriamycin, an intercalating cytostatic agent that is an important component of clinical nonhormonal chemotherapy of breast carcinomas, induced only partial remission of these three xenografts and inhibited the tumor growth by 80%-90% (MDA-MB-436, MX-1) and by 70%-80% (MDA-MB-435S), respectively. In the M 3 xenograft, treosulfan just led to a retardation and stagnation of tumor growth; it was again more effective than Adriamycin but was clearly less active than cyclophosphamide. The FM 2 breast carcinoma, finally, was the only xenograft whose growth was not influenced by treosulfan at doses up to that which was lethal to 50% of the treated mice (LD50 value). These results confirm that treosulfan is effective against human breast carcinomas. Because of this activity as well as the known low toxicity and good clinical compatibility of treosulfan, it should be considered for introduction into nonendocrine chemotherapeutic regimens against human breast carcinomas and investigation in clinical trials.

Comparative effects of Yoshi-864 and busulfan on certain transplantable murine tumors.

Yoshi-864 extends markedly the survival times of mice bearing L1210 leukemia or Ehrlich ascites carcinoma. Busulfan, with methanesulfonate leaving groups identical with those of Yoshi-864, is without effect. Tumor cells from mice bearing the Ehrlich tumor and treated with Yoshi-864 have a persistent reduction in ability to synthesize DNA. Synthesis of DNA in cells from mice treated with busulfan is moderately suppresed at 48 hr after treatment, but returns virtually to the control value at 72 hr.