Acquired resistance of melanoma cells to the antineoplastic agent fotemustine is caused by reactivation of the DNA repair gene MGMT

Acquired resistance to antineoplastic agents is a frequent obstacle in tumor therapy. Malignant melanoma cells are particularly well known for their unresponsiveness to chemotherapy; only about 30% of tumors exhibit a transient clinical response to treatment. In our study, we investigated the molecular mechanism of acquired resistance of melanoma cells (MeWo) to the chloroethylating drug fotemustine. Determination of O(6)-methylguanine-DNA methyltransferase (MGMT) activity showed that MeWo cells that acquired resistance to fotemustine upon repeated treatment with the drug display high MGMT activity, whereas the parental cell line had no detectable MGMT. The resistant cell lines exhibit cross-resistance to other O(6)-alkylating agents, such as N-methyl-N'-nitro-N-nitrosoguanidine. Acquired resistance to fotemustine was alleviated by treatment with the MGMT inhibitor O(6)-benzylguanine demonstrating that reactivation of MGMT is the main underlying cause of acquired alkylating drug resistance. As compared with control cells, both MGMT mRNA and MGMT protein were expressed at a high level in fotemustine resistant cells. Southern blot analysis proved that the MGMT gene was not amplified. There was also only an insignificant difference in the CpG methylation pattern of the MGMT promoter whereas a clear hypermethylation in the body of the gene was observed in fotemustine resistant cells. The conclusion that hypermethylation is responsible for reactivation of the MGMT gene gained support by the finding that MGMT activity significantly declined and cells reverted (partially) to the parental sensitive phenotype upon treatment with 5-azacytidine. This is the first report of acquired resistance to a chloroethylating antineoplastic drug of melanoma cells due to gene hypermethylation.     

B-Raf inhibitor vemurafenib in combination with temozolomide and fotemustine in the killing response of malignant melanoma cells

In the treatment of metastatic melanoma, a highly therapy-refractory cancer, alkylating agents are used and, for the subgroup of BRAF^V600E cancers, the B-Raf inhibitor vemurafenib. Although vemurafenib is initially beneficial, development of drug resistance occurs leading to tumor relapse, which necessitates the requirement for combined or sequential therapy with other drugs, including genotoxic alkylating agents. This leads to the question whether vemurafenib and alkylating agents act synergistically and whether chronic vemurafenib treatment alters the melanoma cell response to alkylating agents. Here we show that a) BRAF^V600E melanoma cells are killed by vemurafenib, driving apoptosis, b) BRAF^V600E melanoma cells are neither more resistant nor sensitive to temozolomide/fotemustine than non-mutant cells, c) combined treatment with vemurafenib plus temozolomide or fotemustine has an additive effect on cell kill, d) acquired vemurafenib resistance of BRAF^V600E melanoma cells does not affect MGMT, MSH2, MSH6, PMS2 and MLH1, nor does it affect the resistance to temozolomide and fotemustine, e) metastatic melanoma biopsies obtained from patients prior to and after vemurafenib treatment did not show a change in the MGMT promoter methylation status and MGMT expression level. The data suggest that consecutive treatment with vemurafenib and alkylating drugs is a reasonable strategy for metastatic melanoma treatment.     

Intra-arterial hepatic fotemustine for the treatment of liver metastases from uveal melanoma: experience in 101 patients.

BACKGROUND: Exclusive liver metastases occur in up to 40% of patients with uveal melanoma associated with a median survival of 2-7 months. Single agent response rates with commonly available chemotherapy are below 10%. We have investigated the use of fotemustine via direct intra-arterial hepatic (i.a.h.) administration in patients with uveal melanoma metastases. PATIENTS AND METHODS: A total of 101 patients from seven centers were treated with i.a.h. fotemustine, administered intra-arterially weekly for a 4-week induction period, and then as a maintenance treatment every 3 weeks until disease progression, unacceptable toxicity or patient refusal. RESULTS: A median of eight fotemustine infusions per patient were delivered (range 1-26). Catheter related complications occurred in 23% of patients; however, this required treatment discontinuation in only 10% of the patients. The overall response rate was 36% with a median overall survival of 15 months and a 2-year survival rate of 29%. LDH, time between diagnosis and treatment start and gender were significant predictors of survival. CONCLUSIONS: Locoregional treatment with fotemustine is well tolerated and seems to improve outcome of this poor prognosis patient population. Median survival rates are among the longest reported and one-third of the patients are still alive at 2 years.     

Temozolomide- and fotemustine-induced apoptosis in human malignant melanoma cells: response related to MGMT, MMR, DSBs, and p53

Malignant melanomas are highly resistant to chemotherapy. First-line chemotherapeutics used in melanoma therapy are the methylating agents dacarbazine (DTIC) and temozolomide (TMZ) and the chloroethylating agents BCNU and fotemustine. Here, we determined the mode of cell death in 11 melanoma cell lines upon exposure to TMZ and fotemustine. We show for the first time that TMZ induces apoptosis in melanoma cells, using therapeutic doses. For both TMZ and fotemustine apoptosis is the dominant mode of cell death. The contribution of necrosis to total cell death varied between 10 and 40%. The O⁶-methylguanine-DNA methyltransferase (MGMT) activity in the cell lines was between 0 and 1100 fmol mg⁻¹ protein, and there was a correlation between MGMT activity and the level of resistance to TMZ and fotemustine. MGMT inactivation by O⁶-benzylguanine sensitized all melanoma cell lines expressing MGMT to TMZ and fotemustine-induced apoptosis, and MGMT transfection attenuated the apoptotic response. This supports that O⁶-alkylguanines are critical lesions involved in the initiation of programmed melanoma cell death. One of the cell lines (MZ7), derived from a patient subjected to DTIC therapy, exhibited a high level of resistance to TMZ without expressing MGMT. This was related to an impaired expression of MSH2 and MSH6. The cells were not cross-resistant to fotemustine. Although these data indicate that methylating drug resistance of melanoma cells can be acquired by down-regulation of mismatch repair, a correlation between MSH2 and MSH6 expression in the different lines and TMZ sensitivity was not found. Apoptosis in melanoma cells induced by TMZ and fotemustine was accompanied by double-strand break (DSB) formation (as determined by H2AX phosphorylation) and caspase-3 and -7 activation as well as PARP cleavage. For TMZ, DSBs correlated significantly with the apoptotic response, whereas for fotemustine a correlation was not found. Melanoma lines expressing p53 wild-type were more resistant to TMZ and fotemustine than p53 mutant melanoma lines, which is in marked contrast to previous data reported for glioma cells treated with TMZ. Overall, the findings are in line with the model that in melanoma cells TMZ-induced O⁶-methylguanine triggers the apoptotic (and necrotic) pathway through DSBs, whereas for chloroethylating agents apoptosis is triggered in a more complex manner.     

Predictive value of the MGMT promoter methylation status in metastatic melanoma patients receiving first-line temozolomide plus bevacizumab in the trial SAKK 50/07

The O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation status is a predictive parameter for the response of malignant gliomas to alkylating agents such as temozolomide. First clinical trials with temozolomide plus bevacizumab therapy in metastatic melanoma patients are ongoing, although the predictive value of the MGMT promoter methylation status in this setting remains unclear. We assessed MGMT promoter methylation in formalin-fixed, primary tumor tissue of metastatic melanoma patients treated with first-line temozolomide and bevacizumab from the trial SAKK 50/07 by methylation-specific polymerase chain reaction. In addition, the MGMT expression levels were also analyzed by MGMT immunohistochemistry. Eleven of 42 primary melanomas (26%) revealed a methylated MGMT promoter. Promoter methylation was significantly associated with response rates CR + PR versus SD + PD according to RECIST (response evaluation criteria in solid tumors) (p<0.05) with a trend to prolonged median progression-free survival (8.1 versus 3.4 months, p>0.05). Immunohistochemically different protein expression patterns with heterogeneous and homogeneous nuclear MGMT expression were identified. Negative MGMT expression levels were associated with overall disease stabilization CR+PR+SD versus PD (p=0.05). There was only a poor correlation between MGMT methylation and lack of MGMT expression. A significant proportion of melanomas have a methylated MGMT promoter. The MGMT promoter methylation status may be a promising predictive marker for temozolomide therapy in metastatic melanoma patients. Larger sample sizes may help to validate significant differences in survival type endpoints.     

Liver metastases from melanoma: hepatic intra-arterial chemotherapy. A retrospective study

The liver is the primary site of metastases in most uveal melanoma patients. We retrospectively investigated intraarterial chemotherapy (IAC) as treatment for patients with hepatic melanoma metastases.Twenty-three patients (18 with uveal melanoma) received fotemustine (14 patients, 61.9%) or carboplatin (9 patients, 31.1%) via hepatic IAC delivery. The catheter was introduced through percutaneous access to the femoral artery with drugs delivered directly to the hepatic artery, and was removed at the end of each treatment cycle. A total of 3 cycles was planned, repeated every 21 days. However, patients with a clinical response could receive more than 3 cycles, provided that the toxic effects were acceptable.IAC was well tolerated and no catheter-related complications or grade 4 toxicities were reported. Considering only uveal melanoma patients, the overall response rate and disease control rate was 16.7% and 38.9%, respectively. Median time to progression was 6.2 months (95% CI 3.7-10.5) and median overall survival was 21 months (95% CI 8-39).IAC is well tolerated and is a valid choice for patients with a poor prognosis since median survival rates are among the longest reported.     

Pilot study of hepatic intraarterial fotemustine chemotherapy for liver metastases from uveal melanoma: a single-center experience with seven patients

Background. Uveal melanoma is characterized by a high frequency of hepatic metastases. For patients with liver metastases, who have a median survival of 5 to 7 months, surgery and systemic conventional chemotherapy have little to offer. Methods. Between February 1995 and July 1999, seven patients with isolated hepatic metastases from uveal melanoma were enrolled into a pilot trial of intraarterial fotemustine therapy. An implantable Port-A-Cath catheter was inserted into the hepatic artery for regional chemotherapy via the gastroduodenal artery. Fotemustine 100 mg/m² was administered intraarterially over a 4-h period. The induction phase consisted of one administration per week for 4 weeks, followed by a 5-week rest period. Maintenance therapy with administration of fotemustine every 3 weeks continued until progression or toxicity. Results. Ten patients were evaluated for the trial. One patient was not eligible because of impaired liver function, and in two patients implantation of the port system was not possible for anatomic reasons. Seven patients received a median of 16 treatment cycles (range, 4–28) and all were evaluable for response. Two patients achieved a partial response (PR), three had stable disease (SD), and tumor progressed in two patients (PD). The median survival time from diagnosis of liver metastasis was 24 months (range, 4 to 50+ months). Two patients survived for more than 2 years and two patients are still alive. The toxicity was low and the treatment could be administered on an outpatient basis. Conclusion. Intraarterial fotemustine treatment of uveal melanoma metastatic to the liver is well tolerated, and in some patients is associated with prolonged survival. Received: May 22, 2000 / Accpted: October 13, 2000     

Treatment of disseminated ocular melanoma with sequential fotemustine,interferon alpha,and interleukin 2

Malignant melanoma of the uvea is remarkable for purely haematogenous dissemination and its tendency to metastasise to the liver. Although the liver is involved in up to 95% of patients, 50% of these also develop extrahepatic metastases, most often in the lungs, bone, skin, and brain. The only effective treatments reported to date relied on hepatic arterial chemoembolisation or -perfusion. The objective of this study was to establish a therapy protocol addressing patients with both sole liver involvement and systemic disease. Forty-eight patients with metastatic ocular melanoma received fotemustine 100 mg m(-2) either as 60-min infusion into the hepatic artery or as 15-min infusion via a peripheral vein, depending on the metastatic sites involved, i.e., restriction to the liver or hepatic together with extrahepatic disease. For the first treatment cycle this infusion was repeated after one week. For all cycles, subsequent to a three week resting period, patients received an immunotherapy consisting of subcutaneous interleukin 2 and interferon alpha(2). Although objective responses were more frequent within the cohort receiving intraarterial fotemustine (21.7 vs 8%), this difference did not translate into a significant benefit in overall survival, i.e., 369 and 349 days, respectively. Of note, this overall survival is much longer than that repeatedly reported for stage IV uveal melanoma not treated with fotemustine, suggesting a therapeutic activity of this cytostatic drug even after systemic administration.     

Uveal melanoma: natural history and treatment options for metastatic disease

In order to evaluate the natural history, prognostic parameters and treatment modalities for metastatic uveal melanoma, a review of the clinical data from the current literature was performed based on a Medline database search. Uveal melanoma represents approximately 5% of all melanomas. It is a distinct clinico-pathological entity, differing in many aspects from cutaneous melanoma. The clinical course is unpredictable and metastatic disease can develop very late after a long disease-free interval. Uveal melanoma metastasizes haematogenously, predominantly to the liver. The most Important prognostic parameters for primary uveal melanoma are tumour diameter, the patient's age and gender, histological features and tumour location. Systemic chemotherapy that is effective in cutaneous melanoma has failed to show activity in uveal melanoma. So far only the BOLD chemotherapy regimen (dacarbazine, lomustine, vincristine and bleomycin) combined with interferon-alpha has been shown to produce an objective tumour response in approximately 20% of previously untreated patients. For metastatic disease localized to the liver, intra-arterial application of fotemustine or carboplatin or chemoembolization with cisplatin have shown useful activity, resulting in a response in up to 40% of patients. Selected patients may benefit from palliative surgery. Immunotherapy with interleukin-2 or interferon-alpha has not shown consistent activity in metastatic uveal melanoma. In conclusion, patients with uveal melanoma metastatic to the liver should undergo one of the local treatment options. Carefully selected patients with extrahepatic disease or patients failing local treatment may benefit from systemic therapy using the BOLD regimen combined with interferon.     

O6-methylguanine-DNA-methyltransferase expression and gene polymorphisms in relation to chemotherapeutic response in metastatic melanoma

In a retrospective study, O(6)-methylguanine-DNA-methyltransferase (MGMT) expression was analysed by immunohistochemistry using monoclonal human anti-MGMT antibody in melanoma metastases in patients receiving dacarbazine (DTIC) as single-drug therapy or as part of combination chemotherapy with DTIC-vindesine or DTIC-vindesine-cisplatin. The correlation of MGMT expression levels with clinical response to chemotherapy was investigated in 79 patients with metastatic melanoma. There was an inverse relationship between MGMT expression and clinical response to DTIC-based chemotherapy (P=0.05). Polymorphisms in the coding region of the MGMT gene were also investigated in tumours from 52 melanoma patients by PCR/SSCP and nucleotide sequence analyses. Single-nucleotide polymorphisms (SNPs) in exon 3 (L53L and L84F) and in exon 5 (I143V/K178R) were identified. There were no differences in the frequencies of these polymorphisms between these melanoma patients and patients with familial melanoma or healthy Swedish individuals. Functional analysis of variants MGMT-I143V and -I143V/K178R was performed by in vitro mutagenesis in Escherichia coli. There was no evidence that these variants decreased the MGMT DNA repair activity compared to the wild-type protein. All melanoma patients with the MGMT 53/84 polymorphism except one had tumours with high MGMT expression. There was no significant correlation between any of the MGMT polymorphisms and clinical response to chemotherapy, although an indication of a lower response rate in patients with SNPs in exon 5 was obtained. Thus, MGMT expression appears to be more related to response to chemotherapy than MGMT polymorphisms in patients with metastatic melanoma.     

A phase II study of the sequential administration of dacarbazine and fotemustine in the treatment of cerebral metastases from malignant melanoma

34 patients with cerebral metastases from malignant melanoma received sequential dacarbazine at 250 mg/m² followed 2 h later by foteraustine at 100 mg/m²; this was repeated on day 8. Maintenance therapy was given every 4 weeks to patients with radiological evidence of response or stable disease until a maximum response was achieved plus two more cycles. A 12% response rate was obtained for cerebral metastases, with 2 complete responses lasting 12 and 36+ months, and 2 partial responses lasting 2.5 and 3.75 months. Toxicity was mainly haematological with grade 3–4 leucopenia and thrombocytopenia in 23.5% of patients. No pulmonary toxicity was seen. This schedule of sequential dacarbazine and fotemustine has low activity against metastatic melanoma, and the response rate for cerebral metastases is not superior to that shown in other studies with single agent fotemustine, but the treatment was well tolerated and can be delivered on an outpatient basis.     

Heterogeneity of O(6)-alkylguanine-DNA alkyltransferase activity in colorectal cancer: implications for treatment

OBJECTIVES: MGMT (O(6)-alkylguanine-DNA alkyltransferase) reverses the carcinogenic, mutagenic and cytotoxic effects of alkylating agents. Measurement of MGMT activity in tumours might thus be of use in selecting those patients with colorectal cancer who may be sensitive to adjuvant alkylating agent therapy. The aim of this study was to assess whether measurement of MGMT activity in a single tumour biopsy is representative of the whole tumour. METHODS: Multiple symmetrically spaced biopsies were taken from colorectal cancers obtained from 9 patients. MGMT activity was then measured in cell-free extracts by quantifying the transfer of [(3)H]methyl group from calf thymus DNA methylated in vitro with N-nitroso-N-[(3)H]-methylurea to the MGMT protein. RESULTS: MGMT activity was detected in all tumour samples with the activity ranging between 3.6 and 36.2 fmol/microg DNA and 202-1,986 fmol/mg protein. Heterogeneity in MGMT activity (ratio of maximum/minimum MGMT levels per tumour) varied between 1.3 and 5.4. CONCLUSIONS: Measurement of MGMT activity in a single biopsy is not necessarily indicative of the level throughout the tumour. The response of colorectal cancers to alkylating agent treatment is likely to be non-uniform both within the tumour and between patients.     

Analysis of O(6)-methylguanine-DNA methyltransferase in melanoma tumours in patients treated with dacarbazine-based chemotherapy

In a retrospective study we analysed the levels of the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) in melanoma metastases in patients receiving dacarbazine (DTIC) either as a single drug or as part of combination chemotherapy regimens, and related the expression levels to the clinical response to treatment. Biopsies of subcutaneous and lymph node metastases obtained before chemotherapy in 65 patients with disseminated malignant melanoma were examined for MGMT protein levels by immunohistochemistry using a monoclonal anti-human MGMT antibody. All patients received chemotherapy with DTIC, given either as a single drug or in combination with vindesine and in some cases cisplatin. DTIC as single agent was given to 44 patients, while 21 received combination chemotherapy. Objective responses to chemotherapy were seen in 12 patients, while 53 patients failed to respond to treatment. The expression of MGMT was determined according to the proportion of antibody-stained tumour cells, using a cut-off level of 50%. In 12 of the patients more than one metastasis was analysed, and in seven of these cases the MGMT expression differed between tumours in the same individual. Among the responders a larger proportion (six out of 12, 50%) had tumours containing less than 50% MGMT-positive tumour cells than among the non-responders (12 out of 53, 23%). These data are consistent with the hypothesis that MGMT contributes to resistance to DTIC-based treatment, although the difference between responders and non-responders with respect to the proportion of MGMT-positive tumour cells was not statistically significant (P = 0.077).     

MGMT基因启动子甲基化检测在脑胶质瘤化疗中的意义

背景与目的：如何预测和克服肿瘤细胞对化疗药物的耐药性,实施个体化治疗是肿瘤化疗急需解决的问题。与基因启动子甲基化密切相关的DNA损伤修复基因O^6-甲基鸟嘌呤-DNA甲基转移酶（O^6-methylguanine-DNA methyhransferase,MGMT）表观沉默与肿瘤对烷化剂药物化疗敏感性密切相关。本研究探讨检测MGMT基因启动子CpG岛甲基化在判断脑胶质瘤患者预后及预测肿瘤对烷化剂药物耐药性中的意义。方法：甲基化特异性PCR（MSP）法检测脑胶质瘤组织及肿瘤细胞株MGMT基因启动子甲基化状态,蛋白印迹和免疫组化法测定蛋白表达。MTF法检测肿瘤细胞株对烷化剂药物敏感性,将患者随访资料针对MGMT甲基化状态绘制Kaplan-Meier生存曲线,并进行log—rank检验分析。结果：39例脑胶质瘤患者组织MGMT基因启动子甲基化发生率为46．2％,蛋白表达阳性率为61．5％,且肿瘤组织中MGMT基因甲基化状态与蛋白表达显著相关（P〈0．05）：6例正常组织均未检测出基因甲基化。MGMT基因过甲基化的脑胶质瘤SHG44细胞株用5-Aza-CdR处理后完全脱甲基化．MGMT蛋白恢复了表达,同时细胞株对烷化剂药物敏感性也发生逆转．由敏感转变为耐受。在采用手术、放疗和烷化剂尼莫司汀化疗等综合治疗的39例脑胶质瘤患者中,MGMT基因甲基化的患者生存率显著高于MGMT基因未甲基化患者（P〈0．05）。结论：MGMT基因甲基化状态与蛋白表达及肿瘤细胞对烷化剂药物敏感性密切相关,有可能替代MGMT蛋白检测成为判断脑胶质瘤患者预后和预测肿瘤对烷化剂化疗耐药性的标志分子。     

Isolated hepatic perfusion with high-dose melphalan for the treatment of uveal melanoma metastases confined to the liver

Uveal melanoma is the most common primary intraocular tumour in adults. After treatment of the primary tumour, up to 50% of patients will ultimately develop metastases. Treatment options for metastases are limited. When uveal melanoma metastases are confined to the liver, isolated hepatic perfusion (IHP) could be a treatment option. Herein, we report the results of a small group of patients with uveal melanoma metastases of the liver treated with IHP. Eight patients with uveal melanoma metastases confined to the liver underwent IHP with high-dose melphalan (200 mg) for 1 h. Toxicity was graded according to the National Cancer Institute Common Toxicity Criteria and tumour response was assessed according to World Health Organization criteria. The tumour response rate (complete or partial remission) was 50%. The median time to progression was 6.7 months (range, 1.7-16.9 months). The overall median survival was 9.9 months (range, 4.7-34.6 months), with a 1 year survival of 50% and a 2 year survival of 37.5%. Three patients experienced grade 3-4 hepatotoxicity which was transient within 3 months. Although only a small group of patients has been treated and evaluated so far, IHP is a treatment option for uveal melanoma metastases confined to the liver which can result in tumour responses and may lead to survival benefits in a selective group of patients.     

Adenovirus-based strategies enhance antitumor capability through p53-mediated downregulation of MGMT in uveal melanoma

Uveal melanoma (UM) is an intractable disease with a low survival rates, despite adequate local treatment, as a result of its metastatic characteristics. Thus, new therapeutic strategies, including combinations of novel gene therapy and traditional chemotherapy, are under investigation to improve long-term prognosis. Dacarbazine or DTIC, an alkylating agent which results in DNA methylation, is most commonly used to treat melanoma but the response is very limited. The O6-methylguanine DNA methyl transferase (MGMT), a DNA repair protein, is involved in chemoresistance in DTIC treatment. We previously investigated a combination of oncolytic adenovirus H101 and the alkylating agent DTIC in the treatment of UM cells in vitro and observed a synergistic antitumor effect. In this study, we validated this result and report an enhanced therapeutic effect in vivo. Our findings also demonstrated that the oncolytic adenovirus H101 decreased MGMT levels via accumulation of p53 overcoming DTIC chemoresistance. Therefore, the clinical therapeutic efficacy of DTIC in the treatment of UM might be improved using this adenovirus-based combination therapy.     

Lack of BRAF mutations in uveal melanoma

RAF proteins are serine/threonine kinases that mediate cellular responses to growth signals by activating the mitogen-activated protein kinase pathway. Mutations in the BRAF gene causing a V599E amino acid substitution that enhance the kinase activity have been described in >60% of cutaneous melanomas and premalignant melanocytic lesions. We have investigated the frequency of BRAF mutations at the expression level in melanomas of the uveal tract. None of the 30 metastases and 10 primary uveal melanomas tested expressed the V599E mutation. In contrast, this mutation was expressed by 65% of cutaneous melanoma samples, confirming previous results. In addition, a double mutation resulting in V599K substitution was detected in two suspect ocular metastases of cutaneous melanoma. Analysis of exon 11, the second common site of BRAF mutations, revealed only wild-type sequences in uveal melanomas. Analysis of tumor lysates showed the presence of phosphorylated mitogen-activated protein kinase, kinase, and mitogen-activated protein kinase in 50% of uveal and 100% of cutaneous melanoma metastases. Taken together, these results suggest that although the common BRAF mutations found in cutaneous melanoma do not play a role in tumorigenesis of uveal tract melanocytes, activation of the RAF/mitogen-activated protein kinase pathway may nevertheless play an important role in uveal melanoma.     

Fotemustine in the Treatment of Brain Primary Tumors and Metastases

Fotemustine is a new chloroethylnitrosourea characterized by the grafting of a phosphonoalanine group onto a nitrosourea radical. Clinical studies using fotemustine have been conducted in malignant glioma, brain metastasis of non-small cell lung cancer, and disseminated malignant melanoma.

In recurrent malignant glioma, fotemustine has been used as a single agent: assessed by computed tomography scan, after 8 weeks, the objective response rate was 26.3% among 38 evaluable patients. Median duration of response was 33 weeks. The main toxicity was hematological (thrombocytopenia and leucopenia). A trial with high-dose fotemustine and autologous bone marrow rescue in newly diagnosed glioma was conducted in 26 patients, and 6 showed a partial response. The median overall survival was approximately 11 months. Myelosuppression was noted in all patients except 1, and other toxicity reported was central nervous system toxicity and epigastric pain. Combined with radiotherapy in 55 patients, a 29% response rate was observed, and this combination was well tolerated and easily manageable on an outpatient basis. Finally, fotemustine has been used intra-arterially, with 10 objective responses observed among 26 evaluable patients.

In brain metastases of non-small cell lung cancer, fotemustine proved to be active with a response rate of 16.7%. Combined with cisplatinum, fotemustine is still under study, but preliminary results are promising.

In cerebral metastases of disseminated malignant melanoma, fotemustine has been evaluated in a total of 140 patients in the various studies: median response rate is 24.3%, ranging from 8.3% to 60.0%.

Fotemustine appears to be a good candidate in the treatment of primary brain tumors and metastases.     

MGMT in primary and recurrent human glioblastomas after radiation and chemotherapy and comparison with p53 status and clinical outcome

The DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) plays a pivotal role in alkylating drug resistance. Here, we determined MGMT activity in primary and recurrent glioblastomas (GBM, WHO grade IV) of patients who received radiation therapy (RT) or RT plus chemotherapy with alkylating agents (temozolomide, chloroethylnitrosoureas). The mean MGMT activity of untreated GBM was 37 +/- 45 (range 0-205) fmol/mg proteins. In the 1st, 2nd and 3rd recurrences, MGMT activity increased from 66 +/- 50 (13-194) to 68 +/- 44 (14-143) and 182 +/- 163 (64-423) fmol/mg protein, respectively. Comparing patients who received RT only with RT plus chemotherapy, a significant increase of MGMT in 1st recurrences was only found after treatment with RT plus chemotherapy, indicating either selection of MGMT expressing cells or induction of the MGMT gene by alkylating agents. The p53 status was not significantly related to the MGMT expression level, although a trend for lower MGMT activity in p53 positively stained tumors was observed. Patients expressing MGMT activity of 相似文献   

Final report of the French multicenter phase II study of the nitrosourea fotemustine in 153 evaluable patients with disseminated malignant melanoma including patients with cerebral metastases

One hundred sixty-nine patients with histologic evidence of disseminated malignant melanoma, including patients with cerebral metastases, were entered into a Phase II study of the nitrosourea fotemustine. The treatment regimen consisted of a 100 mg/m2 1 hour IV infusion every week for 3 consecutive weeks, followed by a 4- to 5-week rest period (induction therapy). In responding or stabilized patients, maintenance therapy consisted of 100 mg/m2 every 3 weeks until the disease progressed. One hundred fifty-three patients were evaluable for response. Three complete responses and 34 partial responses were observed (according to the World Health Organization criteria), leading to an objective response rate of 24.2% (95% confidence interval: 17.4% to 31.0%). Responses were also documented on cerebral (25.0%), visceral (19.2%), or nonvisceral (31.8%) metastatic sites. The median duration of response was 22 weeks (range, 7 to 80 weeks). The objective response rate in previously untreated patients was 30.7% (19 of 62 patients). The main toxicity was hematologic with delayed and reversible leukopenia and/or thrombopenia. The objective response rate observed (especially in untreated patients), the activity on cerebral metastases, and the small amount of extra-hematologic toxicity encountered suggest that fotemustine is an effective drug in disseminated malignant melanoma.