Guía clínica del carcinoma urotelial de vejiga no músculo-invasivo de la Asociación Europea de Urología. Actualización de 2011 / EAU Guidelines on Non-Muscle-Invasive Urothelial Carcinoma of the Bladder, the 2011 Update

Contexto y objetivo: Presentar la guía clínica de la Asociación Europea de Urología (EAU) de 2011 del carcinoma de vejiga no músculo-invasivo (CVNMI). Adquisición de la evidencia: Se ha realizado una revisión sistemática de la literatura publicada entre 2004 y 2010 acerca del diagnóstico y el tratamiento del CVNMI. Se actualizaron las guías clínicas previas, y se asignó un nivel de evidencia (NE) y un grado de recomendación (GR). Síntesis de la evidencia: Los tumores en estadio Ta, T1 o carcinoma in situ (CIS) se agrupan como CVNMI. El diagnóstico depende de la cistoscopia y de la evaluación histológica del tejido obtenido por resección transuretral (RTU) en los tumores papilares o por biopsias de vejiga múltiples en el CIS. En las lesiones papilares, una completa RTU es esencial para el pronóstico del paciente. Cuando la primera resección es incompleta o cuando se detecta un tumor de alto grado o T1, se debe realizar una segunda RTU a las 2-6 semanas. En los tumores papilares, el riesgo tanto de recurrencia como de progresión se puede calcular de manera individual mediante los sistemas de puntuación y tablas de riesgo. La estratificación de los pacientes en grupos de riesgo bajo, intermedio y alto (separando la recidiva y la progresión) es fundamental para recomendar un tratamiento adyuvante. Para los pacientes con bajo riesgo de recurrencia y progresión se recomienda una instilación inmediata de quimioterapia. Los pacientes con riesgo intermedio o alto de recurrencia y riesgo intermedio de progresión deben recibir una instilación inmediata de quimioterapia seguida de un mínimo de un año con inmunoterapia intravesical con bacilo de Calmette-Guérin (BCG) o más instilaciones de quimioterapia. Los tumores papilares con alto riesgo de progresión y CIS deben recibir BCG intravesical durante un año. Se puede ofrecer una cistectomía a los pacientes de más alto riesgo, y por lo menos se recomienda a los pacientes en los que ha fallado la BCG. Conclusión: La versión reducida de esta guía clínica de la EAU presenta una información actualizada sobre el diagnóstico y el tratamiento del CVNMI para la incorporación a la práctica clínica (AU)

Context and objective: To present the 2011 European Association of Urology (EAU) guidelines on non-muscle-invasive bladder cancer (NMIBC).Evidence acquisition: Literature published between 2004 and 2010 on the diagnosis and treatment of NMIBC was systematically reviewed. Previous guidelines were updated, and the level of evidence and grade of recommendation were assigned. Evidence synthesis: Tumours staged as Ta, T1, or carcinoma in situ (CIS) are grouped as NMIBC. Diagnosis depends on cystoscopy and histologic evaluation of the tissue obtained by transurethral resection (TUR) in papillary tumours or by multiple bladder biopsies in CIS. In papillary lesions, a complete TUR is essential for the patient’s prognosis. Where the initial resection is incomplete or where a high-grade or T1 tumour is detected, a second TUR should be performed within 2-6 wk. In papillary tumours, the risks of both recurrence and progression maybe estimated for individual patients using the scoring system and risk tables. The stratification of patients into low-, intermediate-, and high-risk groups (separately for recurrence and progression) is pivotal to recommending adjuvant treatment. For patients with a low risk of tumour recurrence and progression, one immediate instillation of chemotherapy is recommended. Patients with an intermediate or high risk of recurrence and an intermediate risk of progression should receive one immediate instillation of chemotherapy followed by a minimum of 1 yr of bacillus Calmette-Guérin (BCG) intravesical immunotherapy or further instillations of chemotherapy. Papillary tumours with a high risk of progression and CIS should receive intravesical BCG for 1 yr. Cystectomy may be offered to the highest risk patients, and it is at least recommended in BCG failure patients. Conclusions: These abridged EAU guidelines present updated information on the diagnosis and treatment of NMIBC for incorporation into clinical practice (AU)

[EAU guidelines on non-muscle-invasive urothelial carcinoma of the bladder, the 2011 update]. / Guía clínica del carcinoma urotelial de vejiga no músculo-invasivo de la Asociación Europea de Urología. Actualización de 2011.

CONTEXT AND OBJECTIVE: To present the 2011 European Association of Urology (EAU) guidelines on non-muscle-invasive bladder cancer (NMIBC). EVIDENCE ACQUISITION: Literature published between 2004 and 2010 on the diagnosis and treatment of NMIBC was systematically reviewed. Previous guidelines were updated, and the level of evidence and grade of recommendation were assigned. EVIDENCE SYNTHESIS: Tumours staged as Ta, T1, or carcinoma in situ (CIS) are grouped as NMIBC. Diagnosis depends on cystoscopy and histologic evaluation of the tissue obtained by transurethral resection (TUR) in papillary tumours or by multiple bladder biopsies in CIS. In papillary lesions, a complete TUR is essential for the patient's prognosis. Where the initial resection is incomplete or where a high-grade or T1 tumour is detected, a second TUR should be performed within 2-6 wk. In papillary tumours, the risks of both recurrence and progression may be estimated for individual patients using the scoring system and risk tables. The stratification of patients into low-, intermediate-, and high-risk groups (separately for recurrence and progression) is pivotal to recommending adjuvant treatment. For patients with a low risk of tumour recurrence and progression, one immediate instillation of chemotherapy is recommended. Patients with an intermediate or high risk of recurrence and an intermediate risk of progression should receive one immediate instillation of chemotherapy followed by a minimum of 1 yr of bacillus Calmette-Guérin (BCG) intravesical immunotherapy or further instillations of chemotherapy. Papillary tumours with a high risk of progression and CIS should receive intravesical BCG for 1 yr. Cystectomy may be offered to the highest risk patients, and it is at least recommended in BCG failure patients. CONCLUSIONS: These abridged EAU guidelines present updated information on the diagnosis and treatment of NMIBC for incorporation into clinical practice.

[BCG versus photodynamic therapy (PDT) for nonmuscle invasive bladder cancer-a multicentre clinical phase III study]. / BCG versus Photodynamische Therapie (PDT) beim nicht muskelinvasiven Harnblasenkarzinom--eine multizentrische Phase-III-Studie.

PURPOSE: This multicentre phase III study was designed to compare the efficacy of Bacillus Calmette Guérin (BCG) instillations and photodynamic therapy (PDT) in the treatment of patients with intermediate and high-risk nonmuscle invasive bladder cancer. MATERIAL AND METHODS: Inclusion criteria were multifocal pTaG1-G2 tumours, recurrent pTaG1-2 tumours, pTa / 1G3 tumours, and primary or recurrent carcinoma in situ (CIS). All patients were centrally randomised after transurethral resection (TUR) to receive BCG induction and maintenance therapy or a single PDT with Photofrin. The primary endpoint of the trial was recurrence-free survival. Secondary endpoints were the 2-year recurrence rate, the 2-year progression rate, survival, and quality of life. RESULTS: 124 patients (63 PDT group, 61 BCG group) were enrolled at 7 institutions in Germany and Austria. Each patient had a follow-up for 2 years. Of the 124 enrolled patients 105 were eligible for this analysis. Kaplan-Meier curves demonstrated no statistically significant differences between the two therapy arms with respect to recurrence-free survival after randomisation (p = 0.4598). After intention-to-treat analysis and after as-treated analysis, the estimated median recurrence-free survival periods were 24.9 (BCG) versus 16.6 months (PDT) and 25.8 (BCG) versus 14.7 (PDT) months, respectively. CONCLUSIONS: A single PDT with Photofrin(R) in intermediate and high-risk nonmuscle invasive bladder cancer patients could not be shown to be superior to BCG maintenance therapy. Vice versa, the results of this study cannot exclude a superiority of BCG.

[Effect mechanism of intravesical BCG immunotherapy of superficial bladder cancer]. / Wirkmechanismen der intravesikalen BCG-Immuntherapie des oberflächlichen Harnblasenkarzinoms.

Immunotherapy for treatment of solid cancer mostly is an experimental treatment. In contrast, intravesical immunotherapy of superficial bladder cancer with bacille Calmette-Guérin (BCG) is clinically well established and accepted worldwide because of better results compared to topical chemotherapy. BCG is currently regarded as the most successful immunotherapy of cancer. Unfortunately the mechanism of action has not yet been fully clarified. This article gives an overview on the complex research on the mechanisms of actionhighly successful therapy.

[Clinical trials for bladder cancer in Germany]. / Studienlandschaft Blasenkarzinom.

The urothelial cancer section of the Association of Urogenital Oncology (AUO) of the German Cancer Society has successfully performed and published clinical trials on treatment of urothelial neoplasia. During the last decade, around 770 patients have been recruited for several phase I, II and III trials. The majority of trials had been conceived for advanced inoperable stages, but the AUO has also been particularly successful in recruiting large trials on adjuvant chemotherapy after radical cystectomy for locally advanced bladder cancer. Future goals address extending the number of active centers in Germany as well as seeking international collaborations in order to enable timely recruitment of trials that demand an extensive sample size.

[Study participation in urological specialty practices]. / Studienteilnahme in der urologischen Facharztpraxis.

In the past, participation of practicing urologists in clinical trials has been very rare. The reasons for this have been influenced in different ways over the last 10 years, so that the situation has now changed. In this paper, the current motivation for the participation of practicing urologists in research studies is discussed. Moreover, we discuss the ways in which the Association of Urological Oncology (AUO) of the German Cancer Association promotes the participation of colleagues in AUO studies and how the AUO meets the needs of urologists in practice.

[Experimental investigations of the optimal therapy of systemic BCG infection in vivo]. / Experimentelle Untersuchungen zur optimalen Therapie der systemischen BCG-Infektion in vivo.

PURPOSE: Hematogenous spread of BCG after intravesical instillation against bladder cancer is rare, but may result in systemic infection and hypersensitivity reaction. We investigated fluoroquinolones and steroids in an animal model to improve the therapeutic options in local and systemic BCG infection. Furthermore, we tested the antitumor effectiveness of intravesical BCG with simultaneous application of fluoroquinolones and/or steroids. METHODS: After systemic BCG infection, experiments were performed with quinolones as antimicrobial agent. Trimethoprim/sulfamethoxazole (TMS) was also tested in comparison to quinolones as a non-specific antimicrobial agent. To evaluate the hyperergic reaction after repeated BCG infection (hypersensitivity model), re-infection was performed seven days after primary infection with accompanying oral antimicrobial therapy with and without steroids. Intravesical tumor therapy was carried out with BCG in orthotopic murine bladder tumor model MB 49 together with simultaneous antimicrobial therapy. RESULTS: After primary infection, quinolones led to a significant prolonged survival independent of steroid administration. Steroids alone after primary BCG infection reduced the survival. In contrast to these experiments, only steroid-treated mice had a significant improvement in survival after a second challenge with BCG. Therapeutic efficacy of BCG was not affected by antibacterial therapy with quinolones. Steroids alone induced a significantly increased death rate during intravesical BCG therapy. CONCLUSION: Quinolones have a positive effect on survival in acute systemic BCG infection in mice. Re-infection with BCG led to severe hyperergic reaction that can only be influenced by steroids. Thus, quinolones can be used in primary systemic BCG infection after topical application as a sufficient alternative to common tuberculostatics. Repeated BCG instillation may lead to hyperergic reaction, making additional administration of steroids essential. In this animal model, therapeutic efficacy of BCG obviously was not affected by additional administration of antimicrobials.

EAU guidelines on diagnosis and treatment of upper urinary tract transitional cell carcinoma.

OBJECTIVES: On behalf of the European Association of Urology (EAU) guidelines for diagnosis, therapy and follow-up of upper urinary tract transitional cell carcinoma (UUTT) patients were established. Criteria for recommendations are based of level 2 only, as large randomised clinical trials have not been performed in this type of disease. METHOD: A systematic literature research using Medline Services was conducted. References were weighted by a panel of experts. RESULTS: TNM classification 2002 is recommended. Recommendations are developed for diagnosis, radical and conservative treatment and for local chemo-immunotherapy. Prognostic factors are defined. Recommendations for follow-up after different types of treatment are given.

Ki-67-directed antisense therapy in an orthotopic renal cell carcinoma model.

PURPOSE: The Ki-67 antigen is only present in proliferating cells. We have shown previously that phosphorothioate-modified antisense oligonucleotides (ON) against this antigen are potent antitumoral agents in bladder and prostate cancer-derived cells. Since ON are known to accumulate in vivo in the kidney, high local effectivity may be expected. Here, we evaluated and characterized antitumoral effects in an orthotopic renal cell cancer (RENCA) model. MATERIAL AND METHODS: RENCA cells were incubated with antisense and control ON in the presence of a cationic lipid. Uptake studies were performed with FITC-labeled ON. Ki-67 protein analysis after ON treatment was performed by immunohistochemical staining. For animal studies, 1 x 10(5) RENCA cells were implanted under the renal capsule of Balb/c mice. Antisense and control ON were injected intraperitoneally daily for 14 days. Tumor weights and status of metastasis were documented after sacrifice. Furthermore, vessel density in tumor tissues was determined by CD31 immunolabeling. RESULTS: Antisense treatment of RENCA cells resulted in specific reduction of the Ki-67 protein and inhibition of cell growth. A substantial cellular uptake of labeled ON was noted in vitro and in vivo. The growth of orthotopically implantated syngeneic kidney tumors in immunocompetent mice was significantly inhibited in antisense-treated animals (p < 0.05). Furthermore, lung metastases were noted in 10% of antisense-treated animals compared to 30-40% in control groups. Immunohistochemical staining of the vessel density showed no significant difference among treatment groups. CONCLUSIONS: The results demonstrate that Ki-67-directed antisense oligonucleotides are potent inhibitors of target protein expression and proliferation of tumor cells in vitro, and of tumor growth and lung metastasis formation in murine renal cell carcinoma whereas tumor vascularization is not significantly affected.

Intravesical bacille Calmette-Guérin versus mitomycin C in superficial bladder cancer: formal meta-analysis of comparative studies on tumor progression.

OBJECTIVES: To compare the therapeutic efficacy of intravesical bacille Calmette-Guérin (BCG) with mitomycin C (MMC) on progression of Stage Ta and T1 bladder carcinoma. METHODS: Combined published and unpublished data from comparative studies on BCG versus MMC in superficial bladder carcinoma were analyzed, considering possible confounding factors. Odds ratios (ORs) and 95% confidence intervals (CIs) were used as the primary effect size estimate. Tumor progression was defined as progression to a higher tumor stage or the development of metastatic disease. RESULTS: In nine eligible clinical trials, 1277 patients were treated with BCG and 1133 with MMC. Within the overall median follow-up of 26 months, 7.67% of the patients in the BCG group and 9.44% of the patients in the MMC group developed tumor progression. In all nine individual studies and in the combined results, no statistically significant difference in the ORs for progression between the BCG and MMC-treated groups was found (combined OR = 0.77; 95% CI 0.57 to 1.03; P = 0.081). In the subgroup with BCG maintenance, the combined result of the five individual studies showed a statistically significant superiority of BCG over MMC (OR = 0.66; 95% CI 0.47 to 0.94; P = 0.02). In the four studies without BCG maintenance, the combined result indicated no statistically significant difference between the two treatments (OR = 1.16; 95% CI 0.65 to 2.07; P = 0.612). Potential confounders, such as tumor risk status, duration of follow-up, BCG strain, BCG and MMC treatment regimen, and year of publication did not significantly influence these results. CONCLUSIONS: The results demonstrated statistically significant superiority for BCG compared with MMC for the prevention of tumor progression only if BCG maintenance therapy was provided.

Elevation of CA 19-9 in giant hydronephrosis induced by a renal calculus.

CA 19-9 is a tumor marker of pancreatic and gastrointestinal cancer. Elevation in nonmalignant disease is rare. The case of a patient with a partial staghorn calculus, giant hydronephrosis, and elevated CA 19-9 serum levels is presented. Open transperitoneal right-sided nephrectomy was performed. In immunohistochemical analysis, CA 19-9 was expressed in the renal tubular epithelium and the renal pelvis. During postoperative follow-up, the CA 19-9 levels returned to normal. Hydronephrosis might cause false-positive results when CA 19-9 measurement is used to screen for malignant disease. Posttreatment CA 19-9 levels of patients with hydronephrosis have to be monitored closely to safely exclude malignant disease.

[Basics of antisense oligonucleotide therapy and current therapeutical strategies in urology]. / Grundlagen der Antisense-Oligonukleotid-Therapie und derzeitige Therapiestrategien in der Urologie.

Antisense oligonucleotides are short DNA sequences designed to modulate the information transfer from gene to protein. Sequence-related hybridisation with the mRNA of a specific protein results in selective inhibition of gene expression and downregulation of protein expression. This allows the study of gene function and therapy on a molecular level. Antisense oligonucleotide inhibitors can be designed directly from genomic sequence information by simply making the reversed complement of the desired sequence. In this review, we focus on the mechanisms of action of antisense oligonucleotides and summarize the progress in urological antisense therapy. The ability to inhibit individual gene expression with antisense oligonucleotides has been promising in preclinical cancer models. Current clinical studies test antisense compounds targeted against various cancer related genes. Although some of these studies comprise patients with urological tumors, such as advanced prostate cancer, experimental antisense therapy in urology is still in its infancy.

[Non-invasive urinary diagnosis of bladder cancer. What do we know?]. / Nichtinvasive Urindiagnostik des Harnblasenkarzinoms. Was ist gesichert?

Although the current system of classifying bladder cancer by stage and histological grade is very useful, it is still difficult to predict the natural progression of the disease either with or without therapy. Cystoscopy and urine cytology are currently the gold standards in the monitoring and diagnosis of bladder cancer. Classical urine cytology is, however, at least in the diagnosis of G1-tumors, characterized by a relatively low sensitivity. In the last few years, the molecular biological investigation of the basic mechanisms involved in carcinogenesis has provided a host of markers which are of potential diagnostic value for bladder cancer. We provide a current, comprehensive review of the literature on bladder tumor markers and summarize their diagnostic and prognostic potential. At present, no diagnostic marker with a comparable sensitivity and specificity to cystoscopy exists, given that cystoscopy has never been evaluated. The combined analysis of several tumor markers seems to be the most promising approach as an adjunct to cystoscopy. Moreover, the increasing simplification of test systems will increase their acceptance by clinicians.

Intravesical bacillus Calmette-Guerin versus mitomycin C for superficial bladder cancer: a formal meta-analysis of comparative studies on recurrence and toxicity.

PURPOSE: We compare the therapeutic efficacy and toxicity of intravesical bacillus Calmette-Guerin (BCG) with mitomycin C on recurrence of stages Ta and T1 bladder carcinoma. MATERIALS AND METHODS: Combined published and unpublished data from comparative studies on BCG versus mitomycin C for superficial bladder carcinoma considering possible confounding factors were analyzed. Odds ratio (OR) and its 95% CI were used as primary effect size estimate. Toxicity data were evaluated descriptively. RESULTS: In 11 eligible clinical trials 1,421 patients were treated with BCG and 1,328 were treated with mitomycin C. Within the overall median followup time of 26 months 38.6% of the patients in the BCG group and 46.4% of those in the mitomycin C group had tumor recurrence. In 7 of 11 studies BCG was significantly superior to mitomycin C, in 3 studies no significant difference was found, while in 1 study mitomycin C was significantly superior to BCG. An overall statistically significant superiority of BCG versus mitomycin C efficacy in reducing tumor recurrence was detected (OR 0.56, 95% CI 0.38 to 0.84, p = 0.005). In the subgroup treated with BCG maintenance all 6 individual studies showed a significant superiority of BCG over mitomycin C (OR 0.43, 95% CI 0.35 to 0.53, p <0.001). In 4 of the 5 studies with reported data on toxicity BCG associated cystitis was significantly more frequent than in the mitomycin C group (53.8% versus 39.2%). The combined cystitis OR was 1.81 (95% CI 1.48 to 2.23, p <0.001). The OR for cystitis in the BCG maintenance group did not significantly differ from that in the nonmaintenance therapy group. CONCLUSIONS: The results suggest superiority of BCG over mitomycin C for prevention of tumor recurrences in the combined data and particularly in the BCG maintenance treatment subgroup, irrespective of the actual (intermediate or high) tumor risk status. The toxicity with BCG is higher but does not differ between BCG maintenance and nonmaintenance groups.

Prognostic significance of a grading system considering tumor heterogeneity in muscle-invasive urothelial carcinoma of the urinary bladder.

The fact that urothelial carcinomas (UC) often contain areas with different histologic grades has been recently shown to bear some prognostic relevance. Here we examined the prognostic significance of a grading system considering tumor heterogeneity in muscle-invasive bladder carcinomas. 151 UC treated by radical cystectomy were included. According to the World Health Organization/International Society of Urological Pathology (WHO/ISUP) classification, histologic grade was low-grade (LG) in 8 and high-grade (HG) in 143 cases. 65 HG tumors which focally harbored LG areas were assigned to mixed-type (MT) carcinomas. Mean follow-up was 50 months. While the WHO/ISUP classification showed no significant correlation with disease-specific survival (p = 0.3995 by log-rank test), stratification into LG/MT and HG tumors had a significant prognostic relevance (p = 0.0404). Nodal status was identified as the only independent prognostic factor (p = 0.0001 by multivariate analysis). In this respect, stratification into LG/MT and HG tumors missed the level of statistical significance by a norrow margin (p = 0.07 by multivariate analysis), but it turned out better than tumor category (p = 0.08). In conclusion, a grading system considering tumor heterogeneity may improve the predictive power of the WHO/ISUP classification in muscle-invasive UC of the urinary bladder. Although the two-tired grading system proposed in this study was not identified as an independent prognostic factor, it may help to obtain additional prognostic information on patients with advanced bladder cancer treated by radical cystectomy.

Optimal treatment of systemic bacillus Calmette-Guérin infection: investigations in an animal model.

PURPOSE: Hematogenous spread of bacillus Calmette-Guerin (BCG) after intravesical instillation for bladder cancer is rare but it may result in systemic infection and hypersensitivity reaction. We investigated fluoroquinolones and steroids in an animal model to improve the therapeutic options in local and systemic BCG infection. Furthermore, the antitumor effectiveness of intravesical BCG with simultaneous application of fluoroquinolones and/or steroids was tested. MATERIALS AND METHODS: Oral antimicrobial therapy with and without steroids was started immediately after intraperitoneal injection using fluoroquinolones or trimethoprim-sulfamethoxazole. To evaluate the therapeutic options against a hyperergic reaction after repeat systemic BCG infection re-challenge was performed with intraperitoneal BCG 7 days after primary infection and oral therapy was given with fluoroquinolones or trimethoprim-sulfamethoxazole with and without steroids. The influence of continuous oral fluoroquinolone therapy on the antitumor effect of BCG was also tested in the MB 49 orthotopic murine bladder tumor model. RESULTS: After primary systemic infection fluoroquinolone therapy alone led to significantly prolonged survival in mice (log rank test p = 0.041), whereas trimethoprim-sulfamethoxazole was ineffective. There was no additional effect of steroid administration. Steroids alone led to premature death (log rank test p = 0.022). After secondary BCG infection only steroid treated animals had prolonged survival (log rank test p = 0.032), whereas antimicrobials alone had no effect. The therapeutic efficacy of BCG in the orthotopic bladder tumor model was not affected by continuous oral fluoroquinolones in terms of survival (log rank test p = 0.001) or bladder weight (Wilcoxon test p = 0.001) compared with untreated controls. CONCLUSIONS: In a mouse model fluoroquinolones had a beneficial effect for primary systemic BCG infections, whereas the hyperergic reaction after repeat BCG infection was susceptible only to steroids. Administering fluoroquinolones during an intravesical treatment course does not affect the antitumor efficacy of BCG.

Antisense oligonucleotide therapy in urology.

PURPOSE: Antisense oligonucleotides are short modified DNA or RNA molecules designed to bind selectively messenger RNA and inhibit synthesis of the encoded protein. In the last 20 years antisense technology has emerged as an exciting and promising strategy, especially for treating cancer. We provide urologists with a contemporary review of relevant background information and outline current treatment strategies and clinical trials of antisense oligonucleotide therapy for urological tumors. MATERIALS AND METHODS: We comprehensively reviewed the literature, including PubMed and recent abstract proceedings from international meetings, on preclinical and clinical studies of antisense oligonucleotide therapy in urology. RESULTS: Current preclinical antisense strategies in urological cancer research include the inhibition of proliferation and induction of tumor cell differentiation, reversal of immunosuppression by tumor secreted molecules and induction of apoptosis. The use of phosphorothioate oligonucleotides as antisense agents has shown promising results in various preclinical cancer models. In recent and current clinical trials in patients with urological tumors antisense agents targeted against c-raf kinase, protein kinase C-alpha, protein kinase A and bcl-2 are being evaluated. CONCLUSIONS: Many compounds have achieved convincing in vitro reduction of target messengerRNA and protein expression. Early clinical trials show safety and mild toxicity at the given doses. Overall the current state of antisense oligonucleotide research described promises a highly productive future for this technology. However, for most medical applications of antisense compounds many obstacles related to nuclease stability, affinity, cellular delivery and specificity remain to be clarified.