The role of caveolin-1 in prostate cancer: clinical implications.

Caveolin-1 (cav-1) is reportedly overexpressed in prostate cancer cells and is associated with disease progression. Specific oncogenic activities of cav-1 associated with Akt activation also occur in prostate cancer. A membrane-associated protein, cav-1, is nonetheless secreted by prostate cancer cells; results of recent studies showed that secreted cav-1 can stimulate cell survival and angiogenic activities, defining a role for cav-1 in the prostate cancer microenvironment. Serum cav-1 levels were also higher in prostate cancer patients than in control men without prostate cancer, and the preoperative serum cav-1 concentration had prognostic potential in men undergoing radical prostatectomy. Secreted cav-1 is therefore a potential biomarker and therapeutic target for prostate cancer.

Therapeutic effects of gelatin matrix-embedded IL-12 gene-modified macrophages in a mouse model of residual prostate cancer.

We evaluated the potential use of intraoperative gelatin matrix hemostatic sealant (GMHS; FloSeal; Baxter Healthcare) embedded with macrophages (Mphi) transduced with murine interleukin (IL)-12 recombinant adenoviral vector (G/Mphi/AdmIL-12) for prevention of recurrence of prostate cancer following radical prostatectomy. Application of G/Mphi/AdmIL-12 resulted in significant suppression of tumor growth and spontaneous lung metastases, a statistically significant survival advantage of the G/Mphi/AdmIL-12-treated animals, more efficient trafficking of Mphi to lymph nodes draining from the prostate and generation of systemic natural killer cell activity and tumor-specific cytolytic T lymphocyte responses compared to the controls in a preclinical mouse model of residual prostate cancer. Our data recommend this treatment as a novel adjuvant for prevention of local recurrence of prostate cancer following radical prostatectomy.

IL-12 gene-modified bone marrow cell therapy suppresses the development of experimental metastatic prostate cancer.

To investigate the immunomodulatory effects of interleukin-12 (IL-12) for treatment of metastatic prostate cancer, we administered adult bone marrow cells (BMC) that were genetically modified by retroviral vector-mediated IL-12 gene transduction in an experimental mouse model of prostate cancer metastasis. This therapy produced significant anti-metastatic effects in bone and lung and prolonged animal survival. Flow cytometric analysis indicated donor BMC could effectively home to bone and lung after treatment. Intensive infiltration of CD4 and CD8T cells in lung metastases and increased systemic natural killer and cytotoxic T lymphocyte activities indicated induction of a significant anti-metastatic immune response after treatment with IL-12 transduced BMC. Our results demonstrate the therapeutic potential of gene-modified BMC gene therapy.

Virus specific immune responses after human neoadjuvant adenovirus-mediated suicide gene therapy for prostate cancer.

PURPOSE: Neoadjuvant gene therapy potentially improves the outcome of primary treatment of prostate cancer by radical prostatectomy in patients with high risk of recurrence. We conducted a Phase I escalating dose study with a replication-defective adenovirus expressing the herpes simplex virus-thymidine kinase gene (Adv-HSV-tk vector). The primary end point was toxicity, while the evaluation of the patients' cellular and humoral immune responses served as a secondary endpoint. MATERIAL AND METHODS: The Adv-HSV-tk vector was injected into the prostate in two doses (2x10(10) to 2x10(11) viral particles), followed by ganciclovir twice daily for 14 days and retropubic radical prostatectomy on day 21. Adenovirus-specific neutralizing, IgG and IgA antibodies were evaluated. Peripheral blood mononuclear cells (PBMC) were stimulated by Adv-HSV-tk and analysed for IFN-gamma production and 3H-thymidine incorporation. Prostate specimens were immunostained for B (CD20+) and for T (CD3+) lymphocytes. RESULTS: Toxicity was minor in all 8 patients treated. In the prostate, no virus related cytopathic effect could be observed. Dose-dependent infiltration of T and B lymphocytes in the whole prostate and in tumor areas was observed. Boosting of adenovirus-specific antibody responses was observed in 7 patients, and an increased adenovirus-specific PBMC proliferation and IFN-gamma production was seen after Adv-HSV-tk stimulation. CONCLUSION: Neo-adjuvant adenovirus-mediated cytotoxic gene therapy prior to prostatectomy for prostate cancer is feasible and safe in an outpatient setting for intraprostatic vector doses up to 2x10(11) viral particles. Activation of the immune system was observed. Application of higher vector doses may be considered.

The emerging role of the PI3-K-Akt pathway in prostate cancer progression.

The PI3-K-Akt pathway plays a central role in the development and progression of prostate cancer and other malignancies. We review original studies and summarize relevant sections of previous reviews concerning the relationships between abnormalities in the PI3-K-Akt pathway and prostate cancer progression. We discuss laboratory and clinical data that indicate gene perturbation and dysregulation of PI3-K-Akt pathway is common in prostate cancer and other malignancies. We further discuss the critical role of the PI3-K-Akt pathway in the oncogenic signaling network and provide examples that establish the PI3-K-Akt pathway as a focal point for the future development of informative biomarkers and effective therapies for prostate cancer.

In situ gene therapy for prostate cancer: immunomodulatory approaches.

The development of effective treatments for prostate cancer is thwarted by the natural history of the disease. The biological and clinical potential of most individual cancers is uncertain. In many cases the disease will not progress to clinical significance but experimental and clinical studies indicate that prostate cancer can and may metastasis early in the course of the disease from relatively small foci (i.e., not necessarily the largest or index cancer). Localised prostate cancer is potentially curable with localised therapies (radical prostatectomy or irradiation therapy). However, there are no curative therapies for metastatic prostate cancer. Gene therapy, especially those approaches with an immunomodulatory component, may provide additional therapeutic options with the potential to affect both localised and systemic disease. We have pioneered the development and application of in situ gene therapy protocols using adenoviral vectors to transduce specific genes that generate cytotoxic activity and/or a systemic antitumour immune response. In addition we have completed initial studies that demonstrate the therapeutic potential of adenoviral vector-mediated gene modified cell-based vaccines. Our review discusses preclinical studies focused on the development of immunostimulatory in situ gene therapy approaches that hopefully will provide novel and effective treatments for localised and metastatic prostate cancer.

Bilateral nerve grafting during radical retropubic prostatectomy: extended follow-up.

OBJECTIVES: To confirm the benefit of using an interposition sural nerve graft at the time of radical retropubic prostatectomy in an extended series of men with at least 1 year of follow-up. We previously reported the return of erectile function after resection of both cavernous nerves. METHODS: Twenty-eight potent men with clinically localized prostate cancer underwent radical retropubic prostatectomy with deliberate wide bilateral neurovascular bundle resection and the placement of bilateral nerve grafts. Erectile dysfunction questionnaires and patient interviews were completed at 6-month intervals. A minimum of 12 months of follow-up (mean 23 +/- 10 months) was obtained for 23 men (mean age 58 +/- 6 years). A control group of 12 men who underwent bilateral nerve resections, but declined nerve graft placement, was also followed up. RESULTS: Of the 23 men, 6 (26%) had spontaneous, medically unassisted erections sufficient for sexual intercourse with vaginal penetration. An additional 6 men (26%) described "40% to 60%" spontaneous erections (fullness, no rigidity, not able to penetrate). Ten men (43%) had intercourse with sildenafil. No demonstrable erections occurred before 5 months postoperatively. The greatest return of function thus far was observed at 18 months after surgery. CONCLUSIONS: This surgical technique continues to show promise as an advance in prostate cancer surgery. The results of this study demonstrated recovery of erectile function in men who underwent bilateral nerve graft placement during radical retropubic prostatectomy when both cavernous nerves were deliberately resected.

Prostate-specific antigen response and systemic T cell activation after in situ gene therapy in prostate cancer patients failing radiotherapy.

In an extended phase I/II study we evaluated 36 prostate cancer patients with local recurrence after radiotherapy who received single or repeated cycles of replication-deficient adenoviral vector (ADV)-mediated herpes simplex virus-thymidine kinase (HSV-tk) plus ganciclovir (GCV) in situ gene therapy with respect to serum PSA levels, alterations in immune cells, and numbers of apoptotic cells in needle biopsies. An initial cycle of HSV-tk plus GCV gene therapy caused a significant prolongation of the mean serum PSA-doubling time (PSADT) from 15.9 to 42.5 months (p = 0.0271) and in 28 of the injected patients (77.8%) there was a mean PSA reduction (PSAR) of 28%. It took a mean of 8.5 months for the PSA to return to the initial PSA (TR-PSA) value. A repeated cycle of gene therapy failed to significantly extend PSADT but did result in significant increases in PSAR (29.4%) and TR-PSA (10.5 months). Moderately increased serum adenovirus antibody titers were generally observed 2 weeks after initial vector injection. Also at this time there was a statistically significant increase in the mean percent of CD8(+) T cells positive for the HLA-DR marker of activation in peripheral blood (p = 0.0088). Studies using prostate biopsies obtained at the same time point demonstrated that vector DNA was detectable by PCR in most samples yet all patients remained positive for prostate cancer in at least one biopsy core. Further analysis demonstrated a correlation between the level of CD8(+) cells and the number of apoptotic cells in biopsies containing cancer cells (p = 0.042). We conclude that repeated cycles of in situ HSV-tk plus GCV gene therapy can be administered to prostate cancer patients who failed radiotherapy and have a localized recurrence. Biological responses to this experimental therapy including increases in PSADT, PSAR, and TR-PSA, and activated CD8(+) T cells present in the peripheral blood, were demonstrated. Interestingly, the density of CD8(+) cells in posttreatment biopsies correlated with the number of apoptotic cells.

Phase I/II trial evaluating combined radiotherapy and in situ gene therapy with or without hormonal therapy in the treatment of prostate cancer--a preliminary report.

PURPOSE: To report the preliminary results of a Phase I/II study combining radiotherapy and in situ gene therapy (adenovirus/herpes simplex virus thymidine kinase gene/valacyclovir) with or without hormonal therapy in the treatment of prostate cancer. METHODS AND MATERIALS: Arm A: low-risk patients (T1-T2a, Gleason score <7, pretreatment PSA <10) were treated with combined radio-gene therapy. A mean dose of 76 Gy was delivered to the prostate with intensity-modulated radiotherapy. Arm B: high-risk patients (T2b-T3, Gleason score >or=7, pretreatment PSA >or=10) were treated with combined radio-gene therapy and hormonal therapy. Hormonal therapy was comprised of a 4-month leuprolide injection and 2-week use of flutamide. Arm C: Stage D1 (positive pelvic lymph node) patients received the same regimen as Arm B, with the additional 45 Gy to the pelvic lymphatics. Treatment-related toxicity was assessed using Cancer Therapy Evaluation Program common toxicity score and Radiation Therapy Oncology Group (RTOG) toxicity score. RESULTS: Thirty patients (13 in Arm A, 14 in Arm B, and 3 in Arm C) completed the trial. Median follow-up was 5.5 months. Eleven patients (37%) developed flu-like symptoms (Cancer Therapy Evaluation Program Grade 1) of fatigue and chills/rigors after gene therapy injection but recovered within 24 h. Four patients (13%) and 2 patients (7%) developed Grade 1 and 2 fever, respectively. There was no patient with weight loss. One patient in Arm B developed Grade 3 elevation in liver enzyme, whereas 11 and 2 patients developed Grade 1 and 2 abnormal liver function tests. There was no Grade 2 or above hematologic toxicity. Three patients had transient rise in creatinine. There was no RTOG Grade 3 or above lower gastrointestinal toxicity. Toxicity levels were as follows: 4 patients (13%), Grade 2; 6 patients (20%), Grade 1; and 20 patients (67%), no toxicity. There was 1 patient with RTOG Grade 3 genitourinary toxicity, 12 patients (40%) with Grade 2, 8 patients (27%) with Grade 1, and 9 patients (30%) with no toxicity. No patient dropped out from the trial or had to withhold treatment because of severe toxicity. CONCLUSIONS: This is the first trial of its kind in the field of prostate cancer that aims to expand the therapeutic index of radiotherapy by combining in situ gene therapy. Initial experience has demonstrated the safety of this approach. There is no added toxicity to each therapy used alone. Long-term follow-up and larger cohort studies are warranted to evaluate long-term toxicity and efficacy.

Optimal combinations of systematic sextant and laterally directed biopsies for the detection of prostate cancer.

PURPOSE: The standard sextant protocol for obtaining transrectal ultrasound guided biopsy of the prostate has been shown to underestimate the presence of prostate cancer. Studies have demonstrated an increased cancer detection rate with additional laterally directed biopsies. We compared the sensitivity of individual biopsy cores and evaluated combinations of these cores to identify an optimal biopsy strategy. MATERIALS AND METHODS: A total of 396 consecutive patients underwent biopsy of the lateral peripheral zone in addition to standard sextant biopsy. The cancer detection rate for each biopsy core was calculated. The sensitivity of different combinations of biopsy cores was compared with those of standard sextant biopsies and with a 12 core biopsy protocol that combined the standard sextant biopsy with a complete set of laterally directed cores. RESULTS: Cancer was detected in 160 of 396 (40.3%) patients. Of the possible combinations of biopsy cores a strategy that included laterally directed cores at the base, mid gland and apex of the prostate with mid lobar base and apical cores detected 98.5% of cancers. The detection rate of this 10 core biopsy regimen was significantly better than that of the standard sextant protocol (p < or =0.001), and was equivalent to that of the 12 core regional biopsy (p > or =0.302). CONCLUSIONS: The standard sextant protocol failed to detect a large proportion of cancers located laterally in the peripheral zone. A 10 core biopsy regimen that combined laterally directed cores at the base, mid gland and apex of the prostate with mid lobar biopsy cores at the base and apex maximizes the sensitivity of transrectal ultrasound guided systematic biopsy.

Bilateral nerve graft during radical retropubic prostatectomy: 1-year followup.

PURPOSE: With the interposition of a sural nerve graft to replace resected cavernous nerves at radical retropubic prostatectomy, we have previously reported the return of effective erectile function. We determine the efficacy of this procedure in a series of men with at least 1-year followup. MATERIALS AND METHODS: A total of 12 potent men (mean age plus or minus standard deviation 57 +/- 6 years) with clinically localized prostate cancer underwent radical retropubic prostatectomy, with deliberate wide bilateral neurovascular bundle resection and placement of bilateral nerve grafts. A series of patient and partner erectile dysfunction questionnaires, and patient interviews were performed at 3, 6, 12 and 18 months postoperatively. Only results for those men with a followup of 12 months or greater (mean 16 +/- 4) are presented. A control group of 12 men who had undergone bilateral nerve resection but declined nerve graft placement, was also followed. RESULTS: Of the 12 men 4 (33%) had spontaneous medically unassisted erections sufficient for sexual intercourse with vaginal penetration. An additional 5 (42%) men describe "40 to 60%" spontaneous erections, with fullness, no rigidity and not able to penetrate. Overall, 9 (75%) men had return of erectile activity. No demonstrable erections occurred before 5 months postoperatively. The greatest return of function was observed at 14 to 18 months after surgery. CONCLUSIONS: This surgical technique has minimal morbidity and represents a significant advance in prostate cancer surgery in men requiring bilateral nerve resection. Our study clearly demonstrates recovery of erectile function in men who underwent bilateral nerve graft placement during radical retropubic prostatectomy when both cavernous nerves were deliberately resected.

In vivo surgical resection plus adjuvant gene therapy in the treatment of mammary and prostate cancer.

Adenoviral-mediated gene therapy delivery, combining the herpes simplex virus thymidine kinase gene (Ad-tk) with gancyclovir, has been evaluated as a treatment modality for numerous tumors in the laboratory and in the clinics. As a single modality, gene therapy has shown some promising local and systemic results but no curative success. Surgery is the standard of care for many solid tumors. However, minor residual tumor following surgical resection can lead to local recurrence, and surgery is neither efficient nor plausible for metastatic disease. In this study, two tumor models were used to evaluate the effects of Ad-tk gene therapy as an adjuvant to surgery. Subcutaneous mammary- and prostate-derived tumors were produced in syngeneic mice. To evaluate systemic effects, tumor cells were injected intravenously, with subsequent formation of lung nodules. The subcutaneous tumors were surgically resected and the tumor bed was bathed with saline or Ad-tk. The animals were evaluated for toxicity, local tumor recurrence, survival, and lung nodule formation. No evidence of additional toxicity was observed. In the less aggressive mammary model, the time to recurrence was increased from 11.7 (+/-1.0) days to 22.7 (+/-5.5) days. In the prostate model, recurrence went from a mean of 17.3 (+/-5.6) to 22.6 (+/-6.8) days. Survival was also improved from a mean of 19.7 (+/-1.1) to 32.3 (+/-4.8) and 26.1 (+/-5.0) to 34.1 (+/-6.1) days in the mammary and prostate models, respectively. Evidence of systemic benefits from the use of adjuvant Ad-tk therapy was demonstrated by a significant reduction in lung nodules from a mean of 17 to 3.5. These results suggest that Ad-tk gene therapy may be a useful adjuvant for patients undergoing surgery for treatment of cancer.

Fenretinide therapy in prostate cancer: effects on tissue and serum retinoid concentration.

PURPOSE: To examine the feasibility of using fenretinide (4-HPR) for the prevention and treatment of prostate cancer. MATERIALS AND METHODS: We measured the impact of 4-HPR therapy on retinoid concentrations in vivo, in a mouse model of prostate cancer and clinically, in patients with prostate cancer who were given oral 4-HPR (200 mg/d) or placebo for 4 weeks before undergoing a radical prostatectomy. RESULTS: Prostate tumors in mice treated with 4-HPR contained high levels of 4-HPR and of all-trans-retinoic acid (RA) and reduced levels of retinol (ROH). Patients given 4-HPR were found to have significantly higher concentrations of 4-HPR in the cancerous prostate as compared with the serum levels (463 nmol/L v 326 nmol/L; P =.049), but they were only 1/10 the levels found in mice and were far below the concentrations reported in human breast tissue. Serum and tissue ROH levels were reduced to less than half the concentrations found in untreated controls. RA concentrations in human serum and in cancerous prostates were not significantly affected by 4-HPR treatment, in contrast with the findings in mice. CONCLUSION: The standard oral dose of 4-HPR proposed for breast cancer (200 mg/d) achieved only modest drug levels in the prostate and is unlikely to be effective for prostate cancer prevention or treatment. Higher doses need to be explored.

Effect of 13-cis-retinoic acid on serum prostate-specific antigen levels in patients with recurrent prostate cancer after radical prostatectomy.

The objective of this study was to determine whether there is any beneficial effect of oral 13-cis-retinoic acid (isotretinoin) on prostate cancer, using serum prostate-specific antigen (PSA) levels as a surrogate end point in patients with a rising serum PSA after radical prostatectomy. In the first phase, the effect of the drug on the serum PSA level was tested in 14 control patients with normal prostates. Our goal was to exclude any effect of isotretinoin on PSA secretion and metabolism and thus to validate any observed effect on PSA as indicative of anticancer activity. In the second phase, patients with rising PSA levels after radical prostatectomy and no evidence of metastatic disease were treated with oral isotretinoin at a daily dose of 1.0 mg/kg. Serum PSA levels were checked monthly for the first 4 months after initiation of treatment and every 3 months thereafter. No significant changes in serum PSA levels after 3 months of isotretinoin treatment were recorded in the control group (P = 1.000). Three of 11 postprostatectomy patients (27%) had a PSA reduction of 28%, 15%, and 6.6% after initiation of treatment that lasted for a period of 2-3 months. In two of these three patients, the PSA levels subsequently rose exponentially. Another patient displayed a stabilization of the serum PSA curve for 3 months after an initial sharp rise. No grade 3 or 4 toxicity was recorded in this group of patients. Isotretinoin had a modest, transient effect on the serum PSA level in 4 of 11 (36%) patients with a rising serum PSA after radical prostatectomy. We conclude that this drug is unlikely to be of major therapeutic benefit in prostate cancer patients when used as a single agent. However, its modest effect argues for the exploration of other, more potent retinoids for prostate cancer therapy.

Cytopathic effect of in situ gene therapy in prostate cancer.

This is a morphologic study of in situ gene therapy effects in patients with prostate cancer using the Herpes Simplex VirusThymidine Kinase gene (HSV-tk) followed by ganciclovir. Prostatectomy specimens from the first 4 patients showed the following morphologic changes: (1) various degrees of necrosis were seen in cancer foci; (2) cytopathic changes were seen across the whole spectrum of Gleason grades; (3) the normal prostate was rarely affected by necrosis, but contained an intense mononuclear infiltrate; (4) loss of nuclear detail was a common finding. Volumetric studies showed that only portions of the tumor show morphologic effects as well as an inverse relationship between percentage of affected tumor and prostate and tumor size. An inflammatory response was observed, with predominance of CD20-positive cells in normal prostate tissue, CD8 (cytotoxic T cells) in the tumor, and macrophages in all areas of the treated prostates. We believe that these changes represent the cytopathic effect of our in situ gene therapy on prostate cancer, and that they trigger a local immune response.

Suicide gene therapy for prostate cancer using a replication-deficient adenovirus containing the herpesvirus thymidine kinase gene.

Current therapies for localized prostate cancer include radical prostatectomy, local radiation therapy, and cryoablation and are associated with a high rate of cure and acceptable morbidity. However, for men who have failed primary curative attempts or have metastatic disease, no effective therapy associated with acceptable morbidity exists. "Suicide" gene therapy delivered alone or in combination with other forms of treatment could potentially provide simultaneous efficacy against localized and systemic disease via the generation of cytotoxic activity and/or systemic immunity to the cancer. In this article we discuss our preclinical and clinical experience with a herpes-simplex-virus thymidine kinase/ganciclovir gene-therapy protocol for prostate cancer.

Suicide gene therapy toxicity after multiple and repeat injections in patients with localized prostate cancer.

PURPOSE: We assess risks, toxicity and side effects of multiple and repeat in situ suicide gene therapy in patients with localized prostate cancer. MATERIALS AND METHODS: The study population comprised patients with localized prostate cancer receiving multiple and/or repeat intraprostatic injections of a replication deficient adenovirus containing the herpes simplex virus thymidine kinase (HSV-tk) gene. Intravenous ganciclovir or oral valaciclovir was given for 14 days after injection. Patients were recruited from 4 different clinical protocols in studies of toxicity and efficacy of suicide gene therapy, and closely monitored for toxicity and side effects during and after treatment. Toxicity was graded according to the Cancer Therapy Evaluation Program common toxicity criteria published by the National Cancer Institute. RESULTS: A total of 52 patients were treated under these clinical protocols with a total of 76 gene therapy cycles. Toxic events were recorded in 16 of 29 patients (55.2%) who were given multiple viral injections into the prostate, 7 of 20 (35%) who received 2 cycles of "suicide" gene therapy and 3 of 4 (75%) who received a third course of gene therapy. All toxic events after multiple or repeat injections were mild (grades 1 to 2) and resolved completely once the therapy course was terminated. No additive toxicity was noted in patients receiving repeat gene therapy cycles. Mean followup was 12.8 months (range 3 to 34). Preliminary results for 28 patients in 2 clinical protocols indicated a mean decrease of 44% in PSA in 43%. CONCLUSIONS: Direct injection into the prostate of a replication defective adenovirus containing the HSV-tk gene followed by intravenous ganciclovir is safe even in repeat cycles.

Unilocular retroperitoneal cyst of mesothelial origin presenting as a renal mass.

We report the first 2 cases, to our knowledge, of retroperitoneal cysts with features of mesothelial differentiation that clinically mimic renal masses. The first lesion occurred in a 71-year-old man who presented with flank pain. Ultrasound and magnetic resonance imaging studies showed a unilocular cystic structure arising from the upper pole of the left kidney. The second lesion was in a 44-year-old woman who presented with left flank pain. Imaging studies revealed an 8-cm hemorrhagic cyst at the lower pole of the left kidney. Histologic examination of the nephrectomy specimens in each case revealed a unilocular cyst with intracystic and pericystic hemorrhage. In each case, the cyst was lined by a single layer of cells with ample eosinophilic cytoplasm and benign nuclear features without mucinous or müllerian differentiation. Histochemical staining showed Alcian blue positivity on the cell surface, which was sensitive to hyaluronidase digestion. Intracytoplasmic mucin, however, was not detected. Immunostaining showed that the cyst lining cells were positive for keratin, vimentin, HBME-1, WT1, and thrombomodulin but negative for carcinoembryonic antigen, B72.3, Leu-M1, and BerEP4. The first case was positive for calretinin, whereas the second was negative. These findings support the mesothelial nature of the cysts.