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C Bokemeyer

Publications and source records attributed to C Bokemeyer.

231 records · Page 13Linked to original sources

Targeting of neoglycoprotein-drug conjugates to cultured human embryonal carcinoma cells.

Fluorescent neoglycoproteins were used to screen for the presence and sugar specificities of cell surface lectins in two human embryonal carcinoma cell lines. Efficient labeling correlated with extent of lectin-mediated uptake of neoglycoproteins, as measured by inhibition of DNA synthesis by drug-neoglycoprotein conjugates. These conjugates contain covalently linked carbohydrate moieties on the carriers to render them accessible to the membrane lectins, most effectively galactosides and alpha-glucosides. They furthermore contain chemically linked cytotoxic drugs (etoposide, cis-diamminedichloroplatinum II and methotrexate) which are intracellularly released after lysosomal breakdown of the carrier, as indicated by the effect of leupeptin. Sugars can confer a greater than 10-fold increase in cytotoxic capacity to the nonglycosylated carrier-drug conjugate, nearly reaching the level of toxicity of the freely diffusible drug. Two different neoglycoproteins, reacting with independently targeted membrane lectins, were shown to be useful in a model for combination chemotherapy. These results therefore suggest potential usefulness of custom-made glycosylated carriers in the targeting of therapeutic agents to human embryonal carcinoma cells.

Antineoplastic Agents↗

Successful treatment of a Trichosporon beigelii septicemia in a granulocytopenic patient with amphotericin B and granulocyte colony-stimulating factor.

Invasive fungal infections have become an increasing problem in severely immunocompromised hosts. We here report a case of septicemia, caused by Trichosporon beigelii, an unusual pathogen of systemic infections. This infection was acquired during a period of severe neutropenia after chemotherapy for relapsed acute myelogenous leukemia following allogeneic bone marrow transplantation. The patient recovered from a life-threatening T. beigelii septicemia due to early intensified treatment with amphotericin B and a rapid neutrophil recovery, enhanced by granulocyte colony-stimulating factor (G-CSF). According to the current literature, amphotericin B is the treatment of choice for systemic T. beigelii infections. In patients with severe granulocytopenia, the rapid recovery of neutrophils remains the most important factor for the outcome of this infection.

Agranulocytosis↗

Current trends in chemotherapy for metastatic nonseminomatous testicular germ cell tumors.

With the introduction of cisplatin-based chemotherapy, metastatic testicular cancer represents a model for a highly curable malignant disease. Approximately 70-80% of patients achieve a durable remission following chemotherapy +/- secondary surgery of residual tumors. With the development of prognostic classifications based on clinically available parameters, the aims of chemotherapy have been twofold: on the one hand, the reduction of toxicity in patients with 'low-risk' metastatic disease without a concomitant reduction in treatment efficacy and, on the other hand, the improvement of treatment results in patients with 'poor-prognosis' criteria who achieve a long-term cure rate of less than 50% with standard chemotherapy regimens. Despite a number of large randomized studies attempting either to avoid the toxicity of bleomycin or to reduce cisplatin-associated side-effects through the substitution with carboplatin, the combination of cisplatin, etoposide and bleomycin (PEB) given at 3-week intervals still remains the standard treatment for metastatic disease. The role of high-dose chemotherapy with autologous stem cell support is currently being investigated in order to improve the outcome of patients with relapse after previous chemotherapy and of patients initially exhibiting advanced metastatic disease. For patients with relapsed disease receiving high-dose chemotherapy, a prognostic score has recently been developed: cisplatin-refractory disease, beta human gonadotropin values > 1,000 U/l or primary mediastinal germ cell tumors are factors characterizing patients which will profit less from high-dose chemotherapy treatment than patients with chemosensitive disease at relapse. Standard dose salvage regimens only result in a 20% long-term survival rate. In contrast, high-dose salvage chemotherapy may yield a cure rate of approximately 40%. However, the only randomized study comparing high-dose versus conventional-dose therapy in patients with relapsed disease is still ongoing. The investigation of dose-intensive approaches as first-line treatment is currently being studied by several institutions. Despite preliminary favorable results, this approach still cannot be considered standard treatment. A randomized study comparing high-dose chemotherapy with 4 cycles of standard PEB was initiated in the USA in 1996. The evaluation of new drugs in testicular cancer patients with absolute cisplatin-refractory disease has demonstrated that paclitaxel is one of the few agents with antitumor activity in these patients. Paclitaxel has therefore been included in combination regimens--such as cisplatin, ifosfamide and paclitaxel--for the treatment of patients with first and second relapse of testicular cancer. These combinations are used as induction therapy prior to high-dose salvage treatment. Due to the large group of patients with metastatic disease being cured nowadays, the long-term side effects of treatment have become even more important. One of the major risk factors for the development of late toxicities such as oto-, neuro-, nephro-, gonadal and cardiovascular toxicity is the cumulative dose of cisplatin applied during therapy. The development of new treatment strategies, such as the use of adjuvant chemotherapy for stage I disease, the widespread application of high-dose chemotherapy with peripheral stem cell rescue and the use of new cytotoxic agents, makes the evaluation of the late effects of treatment for testicular cancer within controlled clinical trials mandatory.

Antineoplastic Combined Chemotherapy Protocols↗

Is continuous 24-hour infusion of 5-fluorouracil plus high-dose folinic acid effective in patients with progressive or recurrent colorectal cancer? A phase II study.

BACKGROUND: To evaluate the therapeutic activity of 24-hour continuously infused 5-fluorouracil (5-FU) modulated by high-dose folinic acid in patients with metastatic colorectal cancer who had recurred or progressed following mainly bolus 5-FU/folinic acid chemotherapy. PATIENTS AND METHODS: Forty-two patients with a median age of 59 years (45-76) were enrolled. Karnofsky status was 90% (80-100), previous chemotherapy regimen bolus 5-FU/folinic acid (n=33, 79%) or 24-hour continuous 5-FU+/-interferon alpha2 (n=9, 21 %). Chemotherapy was given as a weekly infusion of 500 mg/m2 folinic acid over 2 h followed by a 24-hour continuous infusion of 2,600 mg/m2 5-FU for 6 consecutive weeks followed by a 2-week rest period. RESULTS: No complete but 6 partial responses were observed (ORR: 14%, CI95%: 3.5-25.1%) with a median response duration of 7.3 months (range: 1.4-10.6). The median survival from the start of continuous infusion of 5-FU was 11.6 months (range: 2-27, CI95%: 9.4-13.8) and the 1-year survival rate was 46%. Disease stabilization and minor responses were achieved in another 25 patients (61%). WHO grade III/IV diarrhea occurred in 26% of patients, mucositis, nausea/vomiting and hand-foot syndrome in 5% each. Two cases of WHO grade III anemia and leukocytopenia were observed (5% each). Dose reductions had to be performed in 11 patients because of unacceptable diarrhea with subsequent stop of treatment in 2 patients. Progressive disease while receiving previous bolus 5-FU chemotherapy was associated with a lower response rate, shorter progression-free interval and overall survival compared to response and survival of patients who had achieved temporary disease stabilization during previous bolus 5-FU therapy. CONCLUSIONS: Continuous infusion of 5-FU/folinic acid displays activity in pretreated and refractory colorectal cancer with acceptable toxicity. Patients who had achieved disease stabilization or objective remission with previous 5-FU bolus therapy appear to be more likely to benefit from second-line treatment. Questions remaining to be addressed include the optimal starting dose of continuously infused 5-FU and whether the dose of folinic acid can be reduced or completely eliminated with respect to toxicity and health economics.

Adult↗

Evaluation of late nephrotoxicity in long-term survivors of Hodgkin's disease.

Chemotherapy (Ctx) and/or radiotherapy (Rtx) are effective in the treatment of Hodgkin's disease (HD) but potentially involve late toxicities, including nephrotoxic side effects. Therefore a follow-up study has been performed to screen patients for late signs of an impaired tubular or glomerular function and to correlate data of renal function with type of therapy and cumulative doses of cytotoxic agents applied. 81 patients in complete remission for at least 2 years and a median follow-up of 96 (39-304) months, and 53 controls were examined. Clinical routine parameters such as creatinine and electrolytes were determined. A differentiation of proteinuria into the albumin, high molecular weight (HMW) and low molecular weight (LMW) fractions made it possible to assess glomerular and tubular function based on the LMW/HMW ratio. The structural protein fibronectin served as an additional, sensitive marker of glomerular integrity. Routine parameters of kidney function did not show any signs of late nephrotoxicity. However, patients treated for HD had a higher ratio of LMW/HMW in comparison to the group of healthy volunteers (p < 0.01), indicating subclinical tubular renal damage. When the cutoff for tubular damage was defined as LMW/HMW > 1.5, 50% of the patients treated with combined modality, and 42 and 37% of the patients with Ctx or Rtx alone had subclinical tubular alterations, respectively. A tendency towards a higher prevalence of subclinical tubular changes was observed in patients with higher cumulative doses of methotrexate or ifosfamide and in patients with combined Ctx and Rtx with radiation fields involving the renal area. Changes in glomerular function were not observed. It is concluded that treatment of HD is not associated with clinically apparent long-term impairment of renal function but can lead to subclinical alterations. Further clinical implications of these subclinical tubular alterations cannot be assessed at present. A differentiation of proteinuria does not have to be performed routinely but might be useful in the follow-up of selected patients with an increased risk.

Adult↗

Phase II evaluation of 5-fluourouracil plus folinic acid and alpha 2b-interferon in metastatic colorectal cancer.

Biochemical modulation of 5-fluorouracil (5-FU) by folinic acid (FA) increases the response rate in patients with metastatic colorectal cancer compared to 5-FU alone. Phase II trials also demonstrated increased efficacy when interferon was added to 5-FU. In two consecutive trials, 76 patients were treated on days 1-5 with FA 200 mg/m2 plus interferon 5 x 10(6) U/m2 and 5-FU 350 mg/m2 as intravenous bolus injection (n = 33, regimen A) or 5-FU 500 mg/m2 as 2-hour infusion (n = 43, regimen B), repeated every 3 weeks with individual 5-FU dose escalation in steps of 50 (regimen A) or 100 mg/m2 (regimen B). In regimen A 5-FU dose reduction to 300 mg/m2 due to toxicity was necessary in 49% of the patients; in regimen B a 5-FU dose of 600 mg/m2 or above was tolerated by 70% of the patients. Dose-limiting toxicity was severe mucositis and/or diarrhea. Objective responses were observed in 5 of 33 patients (15%) in regimen A (3-28%, 95% confidence interval) and 7 of 41 patients (17%) in regimen B (5-29%, 95% confidence interval). Median time to progression was 4.7 and 4.8 months, and median survival 9.9 and 11.4 months for regimens A and B, respectively. Prolonged 5-FU administration over 2 h allows the administration of a higher 5-FU dose compared to bolus injection with no apparent improvement in antineoplastic efficacy. The addition of interferon to the combination of 5-FU plus FA in this dose and schedule does not seem to improve the response rate but appears to increase treatment toxicity.

Adult↗

Analysis of the cyclin-dependent kinase inhibitor p27Kip1 in muscle invasive bladder cancer.

It has been suggested that a deregulated cell cycle control contributes to the development of human malignancies due to the loss of critical antiproliferative mechanisms. The cell cycle is controlled at two checkpoints, one at the G1-S and another at the G2-M transition. Several genes including the structurally related p21WAF/CIP1 gene, the downstream mediator of the p53 tumor suppressor gene, and the p27Kip1 gene have been identified as inducers of cell cycle arrest at the G1 checkpoint when substantial DNA damage has occurred to avoid further replication of the altered genome. Recently, a heat stable 27 kDa protein, the transcript of the p27Kip1 gene, has been identified and was suggested to substantially participate in cell cycle control at the G1 checkpoint. Previous investigations have correlated decreased expression of the p27Kip1 protein with an increased biological aggressiveness of breast and small cell lung cancer. However, the molecular-genetic analysis of a variety of human malignancies including prostate cancer failed to identify any alteration at the p27Kip1 gene locus, therefore suggesting a loss of p27Kip1 protein expression to result from post-transcriptional/post-translational events or from so far unknown regulatory mechanisms. So far, bladder cancer specimens have neither been investigated for p27Kip1 alterations on the DNA level, nor has the result of molecular genetic analysis been correlated with an immunohistochemically detected expression of the gene product, the p27Kip1 protein. The present study is the first to describe p27Kip1 gene alterations on the DNA level in 3 of 42 muscle invasive bladder cancer specimens. In contrast, loss of p27Kip1 protein expression was observed in 14 of 42 (33%) tumors. According to the previously reported observation in a variety of human malignancies, in bladder cancer loss of p27Kip1 protein expression seems to result from post-transcriptional or post-translational events.

Adult↗

Prognostic value of p27Kip1 and p21WAF/Cip protein expression in muscle invasive bladder cancer.

Two genes, namely p27Kip1 and p21WAF/Cip1 that reveal distinct structural homology, have been identified as inductors of cell cycle arrest at the G1-checkpoint to prevent entry of somatic cells into the S phase of the cell cycle when substantial DNA damage has occurred. It was demonstrated that the p21WAF/Cip1 gene is induced by pathways dependent and independent from a functionally intact p53 tumour suppressor protein. It has been suggested that decreased expression both of the p21WAF/Cip1 and p27Kip1 protein may contribute to the development of human malignancies due to loss of critical antiproliferative mechanisms. So far, the role of altered p21WAF/Cip1 and mainly of a decreased p27Kip1 protein expression in patients with muscle invasive bladder cancer has not been investigated. In the present study, 50 tumour specimens from 50 patients undergoing radical cystectomy (T2-T4) were investigated for different biological and clinical characteristics as possible prognostic factors: age, depth of tumour infiltration (T-stage), histological grading (G), lymph node status as well as immunohistochemical staining for the p21WAF/Cip1 and p27Kip1 proteins. The median recurrence-free survival for patients with and without retained p21WAF/Cip1 protein expression was 54 months (3-86 months) and 13 months (1-40 months), respectively (p=0.07). During univariate analysis, loss of p21WAF/Cip1 protein expression (p=0.02), T-stage (p=0.02) and histological grading (p=0.03) were significant prognostic factors for survival, among which a negative reaction for the p21WAF/Cip1 protein (p=0.02) as well as T-stage (p=0.005) remained independent significant predictors during multivariate analysis. Loss of p27Kip1 protein expression was not correlated with the recurrence-free or the overall survival of the patients. Prospective studies are needed to confirm the independent prognostic potential of cell-cycle associated proteins such as p21WAF/Cip1 in patients with muscle invasive bladder cancer. The availability of more refined prognostic factors should assist decision making regarding the value of more aggressive treatment options, such as adjuvant or neoadjuvant chemotherapy, for defined subgroups of patients.

Adult↗

Comparison of 18FDG-PET with CT scans in the evaluation of patients with residual and recurrent Hodgkin's lymphoma.

The reliable assessment of residual masses after treatment as well as of new lesions suspected for relapse remains a diagnostic problem in patients with Hodgkin's disease (HD). The current study compares the results obtained by CT scan to FDG-PET imaging in a blind analysis with respect to the viability of residual masses and in case of suspected relapse. Between 1/94 and 10/99, 47 comparisons of PET and corresponding CT scans - 26 comparisons in 24 patients with residual tumors and 21 comparisons in 20 patients with suspected relapse of HD - were evaluated by independent reviewers blinded to he results of each other. Patients with primary diagnosis had been treated within trials of the German HD Trial study group. Relapsed patients received intensified salvage chemotherapy regimens. PET was assessed visually and by quantifying glucose uptake (SUV). Changes in size of tumor lesions as well as contrast medium enhancement served as criteria for assessment by CT scans. Results were validated either by histologic examination of a resected mass or biopsy (n=17) or by a clinical follow-up over 6 months following treatment (n=30). In 26 cases with residual lesions FDG-PET showed an increased tracer uptake in 8, 7 of which were true positive (TP) and 1 false positive (FP). Eighteen cases were classified as being negative (no viable HD), 17 true negative (TN) and 1 FN. In the blinded reading of the corresponding CT scans, 10 cases with residual lesions were considered to contain vital lymphoma (2 TP, 8 FP). Sixteen CT scans were classified as negative (10 TP, 6 FN). The resulting sensitivity and specificity of PET were 87.5% and 94.4% in contrast to only 25% and 56% for CT scans. The positive and negative predictive values of PET and CT scans were 87.5% and 94.4% and 20% and 62.5%, respectively. In patients with suspected relapse, sensitivity and positive predictive value for the diagnosis of the relapse were 100% and 86%, respectively, yielding the same results for both methods. FDG-PET performed in HD patients with residual masses appears to offer important additional information regarding the presence of viable HD in these residual lesions. In patients with suspected relapse of HD, FDG-PET seems not to offer any information over CT scans. Using SUVs is not superior to visual assessment of PET alone.

Adult↗

Predictive value of altered p27Kip1 and p21WAF/Cip1 protein expression for the clinical prognosis of patients with localized prostate cancer.

The p21WAF/Cip and the p27Kip1 genes have been identified as inductors of cell cycle arrest at the G1-checkpoint. Alterations of both genes have been suggested to be involved in the development of a variety of human malignancies due to a loss of critical antiproliferative mechanisms. To evaluate the prognostic importance of these alterations for patients with clinically localized prostate cancer, in 86 specimens (T1-T4) from 86 patients undergoing radical prostatectomy at the Department of Urology at Hannover University Medical School, were investigated. The immunohistochemical expression of the p27Kip1 and p21WAF/Cip protein was correlated to recurrence-free and long-term survival, age, depth of tumour infiltration, histological grade and lymph node status in these patients. After a median follow-up of 71 months (1-198 months), 14 of 20 (70%) patients (Group 1) with loss of p27Kip1 protein expression or a relative amount of < 10% of positively stained tumour cells developed recurrent disease in contrast to 18 of 66 (27%) patients (Group 2) with retained p27Kip1 protein expression (> or = 10% of positively stained tumour cells). The median recurrence-free survival times were 39 (4-134) months and 67 (4-198) months for patients in Groups 1 and 2 (p < 0.01), respectively. In multivariate analysis, loss of p27Kip1 protein expression was identified as the only independent prognostic parameter for recurrence-free survival. Univariate analysis (log-rank test) identified histological grading (p < 0.01) and reactivity for p27Kip1 (p = 0.046) (> or = 10% positivity) as prognostic factors for disease-specific long-term survival. However, during multivariate analysis none of the biological variables investigated retained independent prognostic importance regarding overall survival. Neither a low or a high expression of p21Waf/Cip could be correlated with the clinical prognosis of the patients following radical prostatectomy. This study confirms the independent prognostic value of decreased p27Kip1 protein expression in patients with localized prostate cancer, while a prognostic importance of p21Waf/Cip in addition to established patients' and tumour characteristics like tumour stage and histological grading appears rather unlikely.

Adenocarcinoma↗

Chemotherapy for renal cell carcinoma.

Renal cell carcinoma is a chemotherapy-resistant tumor, which, with commonly used cytotoxic agents, exhibit a only marginal response rate when modern objective response criteria are applied. No clear survival benefit for patients treated with chemotherapy has yet been demonstrated, although most trials indicate that responding patients survive longer. Among the more commonly available cytotoxic agents, vinblastine has been repeatedly reported to achieve a 6-9% objective response rate irrespective of the mode of application. 5-fluorouracil- and Floxuridin (FUDR)-based chemotherapy appear to achieve response rates in the range of 5-8%, with slightly better results when applied by chronomodulation schedules. Trials evaluating the recently licensed newer cytotoxic agents have shown no major improvement for the treatment of metastatic renal cell cancer. Studies including the topoisomerase I inhibitors irinotecan and topotecan are ongoing. The taxanes (paclitaxel, docetaxel) have demonstrated no significant activity and gemcitabine has been reported with responses in single patients. Recent treatment approaches based on the biology of renal cell carcinoma with an increased expression of the multiple drug resistance (MDR) phenotype (pgp 170) have used chemotherapy in combination with verapamil or cyclosporine derivates as inhibitors of the MDR-mechanism. The disappointing results of these trials indicate that MDR is not the only mechanism of chemotherapy-resistance in renal cell carcinoma. In conclusion, chemotherapy has a limited role in metastatic renal cell carcinoma and vinblastine is considered the standard treatment. Strict evaluation of new agents acting independently from the MDR-mechanism is necessary in order to identify drugs with an impact in the palliative treatment of advanced renal cell carcinoma.

Antineoplastic Agents↗

Phase II study of continuous 120-hour-infusion of mitomycin C as salvage chemotherapy in patients with progressive or rapidly recurrent gastrointestinal adenocarcinoma.

The aim of the study was to evaluate the therapeutic activity and safety of continuously infused (c.i.) mitomycin C in patients with metastatic gastrointestinal adenocarcinomas recurring after or progressing during chemotherapy. The patients were treated with mitomycin C 20 mg/m2 intravenously over a time period of 120 hours, followed by a 3-week rest. Seventy-eight patients were entered into the study. All the patients were assessable for toxicity and 72 for response evaluation, having completed at least one full course of chemotherapy. Among 52 colorectal cancer patients one single objective response (2%) was observed. Disease stabilisation was achieved in 11 patients (23%). Median survival time was 4.7 months (CI95%, 1.9 to 8.6). In 20 evaluable patients with gastric cancer, one complete and 5 partial remissions were observed [ORR: 30% (CI95%, 9.1-50.9%)]. The median response duration was 2.1 months (range, 2 to 6), and the median survival time 3.6 months (CI95%, 2.1 to 6.0). WHO degree III/IV mucositis, diarrhea and fever/infection each occurred in 6% of the patients. Thrombo- and leukocytopenia (WHO degree III/IV) occurred in 19% and 6% of the patients, respectively. Mitomycin C has some single-agent activity in advanced gastric cancer but no substantial efficacy was seen as in heavily pretreated colorectal carcinoma.

Adenocarcinoma↗

Comparative study of the acute nephrotoxicity from standard dose cisplatin +/- ifosfamide and high-dose chemotherapy with carboplatin and ifosfamide.

The nephrotoxic effects of different platinum compounds based combination chemotherapies were compared. Chemotherapy consisted of either cisplatin fractionated over 5 days (5 x 20 mg/m2) or given as a single-day infusion (1 x 50 mg/m2) plus ifosfamide (4 g/m2) or high-dose chemotherapy was applied including carboplatin (3 x 500 mg/m2) and ifosfamide (3 x 4 g/m2) fractionated over three consecutive days. Conventional parameters such as serum creatinine and glomerular filtration rate (GFR), as well as urinary protein excretion of N-acetyl-beta-D-glucosaminidase (NAG)) and alpha 1-micro-globulin were assessed in 52 patients. Fractionation over 5 days without adding other nephrotoxic agents, i.e. ifosfamide, prevented decreases in GFR following cisplatin, whereas the combination of conventional dose cisplatin and ifosfamide, given as a single-day infusion, and high-dose carboplatin/ifosfamide yielded a pronounced fall of GFR. All groups showed increases in the urinary excretion levels of serum derived proteins and NAG, but with significant differences; about 2 to 3-fold for 5-days cisplatin, 3 to 5-fold for single-day cisplatin/ifosfamide, and 20 to 35-fold for high-dose chemotherapy. Thus, conventional approaches can reduce but not prevent the nephrotoxicity of cisplatin-based chemotherapy. In particular, high-dose chemotherapy regimens including carboplatin and ifosfamide are associated with comparable or even higher nephrotoxicity to single-day cisplatin/ifosfamide. In the light of the long-term consequences of persistent renal damage prevention of nephrotoxicity should be further improved.

Acetylglucosaminidase↗

Phase II trial of trofosfamide in patients with advanced pretreated soft tissue sarcomas.

BACKGROUND: The number of cytostatic agents effective in patients with advanced soft tissue sarcoma is limited. Trofosfamide, an alkylating agent, has been shown to be effective in several solid and haematological tumors. PATIENTS AND METHODS: Eighteen patients with a median age of 57 years (range, 27-78) were treated with oral trofosfamide 300 mg/d for 1 week followed by 150 mg/d given continuously to analyze the efficacy and toxicity of continuous low-dose oral trofosfamide. All had received at least one anthracycline-based chemotherapeutic regimen prior to trofosfamide. RESULTS: Nine patients (50%) achieved stable disease lasting for a median of 5.5+ months (range, 1-9+). The median time to progression was 10+ weeks (range, 4-37+) and the median survival 7+ months (range, 2-13+). Toxicity was mild, grade III degree toxicity was seen in 5 patients (28%): 3/2 patients with anemia/neutropenia and 2 patients with fatigue syndrome. CONCLUSION: No objective remission was observed with oral low-dose trofosfamide in heavily pretreated soft tissue sarcoma patients, but almost half of the patients achieved disease stabilisation for half a year. The moderate toxicity profile observed in this study allows the consideration of trofosfamide as a reasonable palliative treatment option for patients with soft tissue sarcoma.

Administration, Oral↗

The MXI1 tumor suppressor gene is not mutated in primary prostate cancer.

For prostate cancer, allelic deletions from the long arm of chromosome 10 (#10q23-25), the locus of the putative tumor suppressor gene MXI1 (#10q24-25), have been identified as a frequently occurring genetic event. During the development of several human malignancies, the c-myc proto-oncogene has been identified to enhance cellular transformation, mitogenesis and cell proliferation. The MXI1 gene, belonging to the helix-loop-helix (bHLH) gene family, was demonstrated to display tumor suppressor function by antagonizing c-myc induced transcriptional activities. Due to the detection of point mutations in the retained alleles of four primary adenocarcinomas of the prostate, MXI1 gene alterations have been suggested to be involved in the development and/or the progression of prostate cancer. To evaluate the role of MXI1 gene alterations for the development of adenocarcinoma of the prostate, 42 primary prostate cancers of different stage (T1-4) and histological grade (G1-3) were investigated for alterations within exons 4 and 5 of the MXI1 gene (spanning 6 exons in total), encoding for the functional HLH-Zip domain, by RNA-SSCP analysis and direct PCR-DNA-sequencing following the microscopically guided tumor cell dissection from 5 microm fresh-frozen buffer-soaked tissue sections. Even by application of this highly elaborated technical approach, MXI1 gene alterations could not be deleted in any of the tumor specimens investigated. Therefore, a substantial involvement of MXI1 gene alterations in the development of prostate cancer appears unlikely. The newly identified putative tumor suppressor gene PTEN, located at #10q23, might be responsible for the frequently observed allelic deletions from #10q23-25 in prostate cancer.

Adenocarcinoma↗