Androgen-independent Prostate Cancer Patients Research Articles

Prostate cancer small extracellular vesicles participate in androgen-independent transformation of prostate cancer by transferring let-7a-5p

ObjectivesAndrogen deprivation therapy (ADT) is a standard treatment for advanced prostate cancer (PCa). However, after 2–3 years ADT treatment, prostate cancer inevitably transits from androgen-dependent PCa (ADPC) to androgen-independent PCa (AIPC), which has a poor prognosis owing to its unclear mechanism and lack of effective therapeutic targets. Small extracellular vesicles (sEVs) play a vital role in the development of cancer. However, the role of PCa sEVs in the transformation of AIPC remains poorly understood. Materials and methodsTwo different cell models were employed and compared. sEVs from ADPC cells (LNCaP) and AIPC cells (LNCaP-AI + F cells) were isolated and characterized. After co-culture of LNCaP-AI + F sEVs with LNCaP cells and of LNCaP sEVs with LNCaP-AI + F cells, androgen-independent transformation was determined respectively. Mechanically, small RNA sequencing was performed. Androgen-independent transformation was examined by the upregulation and downregulation of miRNA and downstream pathways were analyzed. ResultsLNCaP-AI + F sEVs promoted the androgen-independent transformation of LNCaP cells. Interestingly, LNCaP sEVs exhibited a capacity to reverse the process.Let-7a-5p transfer was demonstrated. Furthermore, let-7a-5p overexpression promotes the androgen-independent transformation and let-7a-5p down-regulation reverses the process. Androgen receptor (AR) and PI3K/Akt pathways were identified and demonstrated by both let-7a-5p regulation and PCa sEVs coculture. ConclusionsPCa sEVs are intimately involved in the regulation of androgen-independent transformation of prostate cancer by transferring the key sEVs molecular let-7a-5p and then activating the AR and PI3K/Akt signaling pathways. Our results provide new perspectives for the development of sEVs and sEVs molecular targeted treatment approaches for AIPC patients.

Iminoenamine based novel androgen receptor antagonist exhibited anti-prostate cancer activity in androgen independent prostate cancer cells through inhibition of AKT pathway

Treatment by androgen receptor (AR) antagonists is one of the regimens for prostate cancer. The prolonged treatment with AR antagonist leads to the expression of point mutation in the ligand binding domain of the AR. This point mutation causes resistance to AR antagonist by converting them into an agonist. The T887A mutated AR was frequently expressed in androgen independent prostate cancer (AIPC) patients. Through literature survey and molecular modelling, we have identified a novel AR antagonist having a bulky β-iminoenamine BF2 complex scaffold. The tested and standard ligands were screened in AR positive (LNCaP, MCF-7 and MDA-MB-453), AR negative (PC3), and non-cancerous (3T3) cell lines through anti-proliferation assay. The ligand, ARA3 was the most potent molecule among all the tested ligands and was 7.6 folds selective for AR positive cell lines. The mechanism of anti-prostate cancer activity of ARA3 was confirmed by western blot, qPCR, and apoptotic assays in LNCaP (T887A positive AR) cells. Structural activity relationship was derived by correlating the in-vitro and in-silico data. Consequently, we have identified the essential functional groups that could prevent the resistance concerning mutant AR. The ARA3 induces the apoptosis in AIPC cells by preventing the AR mediated activation of AKT pathway. The bicalutamide did not induce the apoptosis because it failed to prevent the AR mediated activation of AKT.

Abstract 1559: CCR5-CCRL2 regulates CCL5-induced organ specific metastasis: the in vitro and in vivo studies

Abstract Previous studies of soluble factors in the tumor associated stromal cells demonstrated the elevation of CCL5 expression in prostate cancer patient sera that correlated wit malignant cancer progression. To evaluate the expression level of chemokine receptors in response to chemokines released by reactive stroma, quantitative PCR to evaluate the mRNA level of chemokine receptors was performed. We noticed the significant increased of CCRL2 (86-fold) and CXCR4 (45-fold) in androgen independent prostate cancer (AIPC) cells. This increased of CCRL2 expression also confirmed in malignant lung, breast and rental cells. Knockdown of CCRL2 declined 75% of migration activities induced by CCL5, suggests CCRL2 involve in CCL5 induce cancer migratory activities (t-test, p<0.001). IHC analysis of CCRL2 in paired prostate cancer patients was performed and revealed increasing of CCRL2 expression in malignant prostate cancer locus, whereas no CCRL2 can be detected in the benign region of same patient. Proximity ligation assays (PLAs) of benign, high grade tumor and tissues collected from patients less than 5-year survive demonstrated the PLA signals only in the lethal progression on patients. In vivo xenograft mice model studies demonstrated the organ specific cancer metastasis can be enhanced after overexpressed CCRL2 in cancer cells. Molecular analysis of CCRL2 demonstrated that CCRL2 regulated EZH2 expression in prostate cancer cells. In summary, out studies indicated the increased expression of CCRL2 play a central role in cancer cell migration induced by chemokine CCL5. The released of CCL5, secreted by bone stromal cells after interaction with dormancy cancer cell, may induce directional migration and invasion of circulating cancer cells. Clinical analyses demonstrated increased of CCRL2 in malignant prostate cancer. Inhibition of these homing mechanisms might significantly decreased cancer cell metastatic activities of AIPC patients. Citation Format: Chia-Ling Hsieh, Che-Ming Liu, Shian-Ying Sung. CCR5-CCRL2 regulates CCL5-induced organ specific metastasis: the in vitro and in vivo studies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1559.

Baicalein inhibits prostate cancer cell growth and metastasis via the caveolin-1/AKT/mTOR pathway

Prostate cancer (PCa) is lethal type of genitourinary cancer due to its high morbidity and gradual resistance to androgen deprivation therapy. Accumulating evidence has recently suggested that the daily intake of flavonoids is negatively correlated with the risk of cancer. In this study, we aimed to investigate the potential effects of baicalein on androgen-independent PCa cells and the underlying mechanisms through which baicalein exerts its actions. Cell viability and flow cytometric apoptosis assays indicated that baicalein potently suppressed the growth and induced the apoptosis of DU145 and PC-3 cells in a time- and dose-dependent manner. Consistently, the inhibitory effects of baicalein on migration and invasion were also observed in vitro. Mechanistically, we found that baicalein can suppress caveolin-1 and the phosphorylation of AKT and mTOR in a time- and dose-dependent manner. Moreover, the inhibition of the activation of AKT with LY294002 significantly promoted the apoptosis and metastasis induced by baicalein. In conclusion, these findings suggested that baicalein can induce apoptosis and inhibit metastasis of androgen-independent PCa cells through inhibition of the caveolin-1/AKT/mTOR pathway, which implies that baicalein may be a potential therapeutic agent for the treatment of androgen-independent prostate cancer patients.

Abstract CN08-01: Targeting the androgen receptor in castration-resistant prostate cancer.

Abstract CN08-01: Targeting the androgen receptor in castration-resistant prostate cancer.

Phase II Trial of Oxaliplatin and Capecitabine After Progression to First-Line Chemotherapy in Androgen-Independent Prostate Cancer Patients

Docetaxel plus prednisone is the current standard of care in first-line chemotherapy for metastatic hormone-refractory prostate cancer. However, there is no agent proven as effective after progression to standard docetaxel-based therapy. Platins and capecitabine have shown activity in this setting. A total of 14 patients were included in this prospective, single-center trial. All patients had progressed to first-line docetaxel-based treatment. Patients received oxaliplatin 100 mg/sqm on D1 and capecitabine 1000 mg/sqm/bid on days 1 to 14 every 21 days. Median number of cycles was 3. No unexpected toxicity was observed. Only grade 3 toxicity reported was grade 3 anemia. Of the 14 patients, 3 presented grade 2 neuropathy which was spontaneously resolved. Prostate-specific antigenresponse rate was 57%, with a median time to progression of 14.5 weeks, and overall survival of 24 weeks. In the second-line setting, after receiving docetaxel-based chemotherapy, the combination of oxaliplatin and capecitabine offers promising activity with an excellent safety profile.

Inhibition of Epidermal Growth Factor Receptor Signaling by Saussurea involucrata, a Rare Traditional Chinese Medicinal Herb, in Human Hormone-Resistant Prostate Cancer PC-3 Cells

Prostate carcinoma is the most frequently diagnosed malignancy and the second leading cause of death of men in the United States. To date, no effective therapeutic treatment allows abrogation of the progression of prostate cancer to more invasive forms. In this study, we identified Saussurea involucrata Kar. et Kir., a rare traditional Chinese medicinal herb, as a potential agent for androgen-independent prostate cancer patients and investigated its biological mechanism as an antineoplastic agent. S. involucrata caused a concentration- and time-dependent inhibition of cell proliferation in human hormone-resistant prostate cancer PC-3 cells. Moreover, in vitro studies in a panel of several types of human cancer cell lines revealed that S. involucrata inhibited cell proliferation with high potency. To evaluate the bioactive compounds, we successively extracted the S. involucrata with fractions of methanol (SI-1), ethyl acetate (SI-2), n-butanol (SI-3), and water (SI-4). Among these extracts, SI-2 contains the most effective bioactivity. SI-2 treatment resulted in significant time-dependent growth inhibition together with G1 phase cell cycle arrest and apoptosis in PC3 cells. In addition, SI-2 treatment strongly induced p21WAF1/CIP and p27KIP1 expression, independent of the p53 pathway, and downregulated expression of cyclin D1 and cyclin-dependent kinase 4 (CDK4). SI-2 treatment increased levels of Bax, cytochrome c, activated caspase-3, and active caspase-9 and decreased Bcl-2 expression level. One of the major targets for the therapy in prostate cancer can be epidermal growth factor receptor (EGFR). SI-2 markedly reduced phosphorylation of EGFR and inhibited activation of AKT and STAT3. Moreover, p.o. administration of SI-2 induced a dose-dependent inhibition of PC-3 tumor growth in vivo. In summary, our study identifies S. involucrata as an effective inhibitor of EGFR signaling in human hormone-resistant prostate cancer PC-3 cells. We suggest that S. involucrata could be developed as an agent for the management of EGFR-positive human cancers.

Oral low-dose dexamethasone for androgen-independent prostate cancer patients

We retrospectively evaluated the outcome of oral low-dose dexamethasone (DXM) therapy for androgen-independent prostate cancer (AIPC). Between January 1999 and April 2006, 99 consecutive patients with AIPC were enrolled in this study. The median patient age was 70 years (range 46-86), and the median pretreatment prostate-specific antigen (PSA) level was 243 ng/ml (range 8.2-29600). Median follow-up was 41.9 months (range 11.4-170.4). Upon biochemical failure, patients were treated with oral low-dose DXM. A total of 40 of the 99 cases (40.4%) showed a ≥50% decrease in serum PSA levels (PSA responders). Twenty-five cases (25.2%) showed a <50% decrease in PSA, and the remaining 34 cases (34.3%) had increased PSA levels (PSA non-responders). The median PSA progression-free survival was 3.0 (range 0-27) and 8.0 months (range 2-27) for the entire cohort and PSA responders, respectively. The PSA responders had a significantly increased survival (median 30.1 months) compared to the non-responders (median 8.8 months, P<0.001). Of the 34 patients who were under pain control for bone metastases before the administration of DXM, 23 (67.6%) were able to discontinue the regular use of analgesics. The PSA responders also showed an increase in hemoglobin levels. The change in serum interleukin-6 levels was significantly associated with a response to DXM (P=0.0065). Severe adverse events of DXM were rare. Clinicopathological factors predicting the PSA response to DXM were age, time from initial androgen deprivation therapy to DXM and PSA velocity prior to DXM. In conclusion, oral low-dose DXM led to an acceptable PSA response in patients with AIPC. Thus, this therapy may be an effective and safe alternative for the treatment of AIPC, particularly for patients who are not favourable candidates for chemotherapy.

7050 Evidence of psa decrease with fulvestrant acetate in androgen independent prostate cancer (AIPC) patients

7050 Evidence of psa decrease with fulvestrant acetate in androgen independent prostate cancer (AIPC) patients

Fluorescence in situ hybridization study shows association of PTEN deletion with ERG rearrangement during prostate cancer progression

The link between ERG rearrangement and PTEN (phosphatase and tensin homolog deleted on chromosome 10) deletion is unclear in prostate cancer progression. Using fluorescence in situ hybridization, we systematically validated the frequency and distribution of ERG and PTEN aberrations in a cohort of 73 benign prostate tissues, 59 high-grade prostatic intraepithelial neoplasia (HGPIN) foci, 281 localized prostate cancer and 47 androgen-independent metastatic prostate cancer patients. Overall, ERG rearrangement was present in 15% (5/33) of HGPIN, 45% (121/267) of localized cancers and 35% (15/43) of metastases. By contrast, PTEN deletion was identified in 9% (3/33) of HGPIN, 17% (42/251) of localized cancers and 54% (22/41) of metastases, of which 0%, 40% (17/42) and 45% (10/22) were homozygous, respectively. Concomitance of ERG rearrangement and PTEN deletion was observed in a subset of HGPIN. Significantly, association between PTEN deletion and ERG rearrangement was present both in localized cancers (P=0.0008) and metastases (P=0.02). Further, immunohistochemistry revealed significant correlation of decreased PTEN protein expression with PTEN genomic deletion both in localized and metastatic cancer. Of note, ERG aberration, but not PTEN deletion, was consistently identical both in localized cancer and adjacent HGPIN. Similarly, whereas all metastases (41/41, 100%) shared the same ERG status across multiple sites from the same patient, 5% (2/41) of cases showed discordance for PTEN deletion status across multiple sites. Collectively, our data support PTEN deletion as a late genetic event in human prostate cancer, presumably a ‘second hit’ after ERG rearrangement. PTEN deletion and ERG rearrangement may cooperate, but contribute at different stages, in prostate cancer progression.

D-Limonene sensitizes docetaxel-induced cytotoxicity in human prostate cancer cells: Generation of reactive oxygen species and induction of apoptosis

Background:Clinical trials have shown that docetaxel combined with other novel agents can improve the survival of androgen-independent prostate cancer patients. d-Limonene, a non-nutrient dietary component, has been found to inhibit various cancer cell growths without toxicity. We sought to characterize whether a non-toxic dose of d-limonene may enhance tumor response to docetaxel in an in vitro model of metastatic prostate cancer.Materials and Methods:Human prostate carcinoma DU-145 and normal prostate epithelial PZ-HPV-7 cells were treated with various concentrations of d-limonene, docetaxel or a combination of both, and cell viability was determined by MTT assay. Intracellular reactive oxygen species (ROS), reduced glutathione (GSH) and caspase activity were measured. Apoptosis and apoptosis-related proteins were studied by enzyme-linked immunosorbent assay and Western blotting, respectively.Results:d-Limonene and docetaxel in combination significantly enhanced the cytotoxicity to DU-145 cells than PZ-HPV-7 cells. Exposure of DU-145 cells to a combined d-limonene and docetaxel resulted in higher ROS generation, depletion of GSH, accompanied by increased caspase activity than docetaxel alone. It also triggered a series of effects involving cytochrome c, cleavages of caspase-9, 3 and poly (ADP-ribose) polymerase, and a shift in Bad:Bcl-xL ratio in favor of apoptosis. Apoptotic effect was significantly blocked on pretreatment with N-acetylcystein, indicating that antitumor effect is initiated by ROS generation, and caspase cascades contribute to the cell death.Conclusion:Our results show, for the first time, that d-limonene enhanced the antitumor effect of docetaxel against prostate cancer cells without being toxic to normal prostate epithelial cells. The combined beneficial effect could be through the modulation of proteins involved in mitochondrial pathway of apoptosis. d-Limonene could be used as a potent non-toxic agent to improve the treatment outcome of hormone-refractory prostate cancer with docetaxel.

Low dose combinations of 2-methoxyestradiol and docetaxel block prostate cancer cells in mitosis and increase apoptosis

Clinical trials have shown that chemotherapy with docetaxel (Doc) combined with prednisone can improve survival of patients with androgen-independent prostate cancer (AI-PC). It is likely that the combination of Doc with other novel agents would also improve the survival of AI-PC patients. We investigated whether the combination of Doc and 2-methoxyestradiol (2ME2), an endogenous metabolite of estradiol promising for cancer therapy, can increase apoptotic cell death in prostate cancer cells. Low concentration 2ME2 (0.5−1 μM) + Doc (0.05−0.1 nM) combinations inhibit cell growth, increase G2/M cell cycle arrest, and increase apoptosis more effectively than the single concentrations in a variety of human AI-PC cells. Effects on apoptosis were associated with an increase in p53 protein and a decrease in cyclin A-dependent kinase activity. We then investigated whether the combination of 2ME2 + Doc can increase apoptotic cell death and inhibit the growth of prostate tumors in the FG/Tag transgenic mouse model of AI-PC. Doses of 2ME2 and Doc that increase mitotic cell cycle arrest result in an increase in apoptosis and lower primary prostate tumor weights in FG/Tag mice. High dose 2ME2 + Doc combinations did not increase G2/M cell cycle arrest or apoptosis in AI-PC cell lines and in the FG/Tag mice more than the single drugs. Overall, our data indicate that low dose 2ME2 + Doc combinations may provide a treatment strategy that can improve therapeutic efficacy against AI-PC while reducing toxicity often seen in patients treated with Doc.

A phase II study with single agent erlotinib in chemotherapy-naïve androgen independent prostate cancer (AIPC)

16104 Background: Mechanisms of hormone resistance in AIPC are variable. One mechanism is the epidermal growth factor receptor (EGFR) stimulating cell proliferation. We investigated an oral anti-EGFR inhibitor (Erlotinib) in chemotherapy-naïve AIPC patients (pts). The primary endpoint was the overall clinical benefit defined as the sum of complete response (CR), partial response (PR), and stable disease (SD). Secondary endpoints were time to disease progression (TTP) and toxicities. Methods: Between January 2006 and December 2007, 29 pts were enrolled onto this phase II study. Median age was 78 years (61–96). Median PSA at enrollment was 64.1 ng/dl (9.2- 914.2). Median time from initial diagnosis to starting Erlotinib was 8 years (1–14). Erlotinib was given at 150 mg daily during 4-week cycles until disease progression or intolerability. Response assessment occurred every 2 cycles, including computed tomography of measurable disease areas, bone scans, and serum PSAs. Pts who progressed radiographically but maintained a PSA response or those who progressed biochemically but maintained a radiographic response were considered stable and continued on study. Results: The study has completed accrual. Nineteen pts are currently evaluable. 4 are early in their therapy, 4 withdrew consent, and 2 progressed before completing 2 cycles. Erlotinib was well-tolerated and most toxicities were grade 1 or 2. Hematuria occurred in 3 pts but was deemed unrelated to erlotinib. Grade 3 diarrhea and dehydration occurred in 2 pts (8%). One patient (3.4%) developed grade 3 rash. One pt developed a venothromboemblic event and another developed cord compression early in his therapy. One pt (3.4%) required a dose reduction secondary to grade 3 hand/foot syndrome. One pt (3.4%) was unable to tolerate therapy even at the reduced dose because of grade 3 fatigue. With a median follow up of 10 months (1–23), 20 pts (72%) remain alive. Two pts achieved PR and 3 pts demonstrated SD. The calculated overall clinical benefit was 26% (5 responses out of 19 patients). Although median TTP was 2 months (2–20), the 2 PR patients responded for 20 and 13 months respectively. Conclusions: Erlotinib is safe and has modest single-agent activity in AIPC. Further studies are warranted. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Genentech™ BioOncology Genentech™ BioOncology

Phase II study of sagopilone (ZK-EPO) plus prednisone as first-line chemotherapy in patients with metastatic androgen-independent prostate cancer (AIPC)

5141 Background: The microtubule stabilizer docetaxel, in combination with prednisone, prolongs life in patients with metastatic AIPC. Epothilones are a new class of microtubule stabilizers. The activity and safety of the fully synthetic epothilone B analogue sagopilone (ZK-EPO) was evaluated in chemotherapy-naïve AIPC patients. Methods: Patients with metastatic AIPC received sagopilone, 16 mg/m2 IV over 3 hours every 21 days and prednisone 5 mg PO BID continuously. Treatment was repeated every 21 days for up to 6 cycles. Extended treatment was allowed for patients felt to benefit from treatment at the end of 6 cycles. Among the first 13 patients, 3 responders (consensus PSA criteria) were required for enrollment to continue to a total goal of 46. Results: 29 patients were enrolled between August 2006 and October 2007 and accrual continues. All patients are evaluable for safety and 24 of 29 patients are evaluable for response. Patients who were not evaluable for response include 4 on treatment and 1 who was ineligible. The median number of cycles therapy was 4 (range 1 to 11). Toxicity ≥Grade 3 included: neuropathy 24%, fatigue 8%, diarrhea 4%, dizziness 4%. Of the 24 patients evaluable for response, 5 (21%; 95%CI: 7–42%) met the criteria for PSA response (confirmed ≥50% reduction in PSA) and 14 (58%; 95%CI: 37–78%) had a 30% reduction in PSA within 3 months of enrollment, a measure recently shown to most strongly correlate with subsequent survival in studies of docetaxel. Of 12 patients with radiographic measurable disease, 1 had a confirmed complete response and 1 a confirmed partial response (PR) by RECIST criteria. An additional 4 patients had an unconfirmed PR. Conclusions: Sagopilone is active in AIPC. Further follow-up is required to verify the level of activity and tolerability and to set this in the context of other agents, such as docetaxel combined with prednisone. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Oncology Bayer HealthCare Pharmaceuticals Bayer HealthCare

Cilengitide in asymptomatic metastatic androgen independent prostate cancer (AIPC) patients (pts): A randomized phase II trial

5144 Background: Integrins αvβ3 and αvβ5 are involved in PC metastasis by regulating cell adhesion, migration, invasion, motility and angiogenesis. αvβ3 integrin is important in bone metabolism and may play a role in PC growth in bone. Cilengitide is a selective, competitive inhibitor of αvβ3 and αvβ5 integrins. Methods: Chemo-naïve pts with asymptomatic progressive metastatic AIPCa were randomized to cilengitide 500 mg or 2,000 mg IV 2X/week (wk) in 6-wk cycles using Simon 2-stage optimal design. Disease was assessed q 12 wks. The primary end point was 6 month (m) objective progression rate (PgR) (excluding PSA). Historically a 75% PgR is expected. We hypothesized cilengitide would lower the 6 m PgR to 55%. > 6 pts/arm with no Pg were needed to move to 2nd stage. Pts with asymptomatic Pg at 1st assessment were permitted to receive 1 more cycle followed by reassessment. Secondary end points include safety, response rate, changes in circulating tumor cells (CTCs) and bone markers. Results: 44 pts were accrued to 1st stage. Arms were balanced at baseline except for younger age (median 68yrs vs 74yrs) and lower PSA (median 66ng/ml vs 141ng/ml) in the 2,000mg arm. Median number of cycles was 3/arm (500mg arm: 1–8; 2,000 mg arm: 1- 15). At 6 m, 3 pts (14%) on the 500mg arm and 6 pts (27%) on the 2,000mg arm had not progressed. Best objective response was stable disease (SD); 27% on the 500 mg arm, 36% on 2000mg arm. 50% of the 24 pts who had Pg at 1st assessment stayed on study for an additional cycle. There were 3 grade (G) 3 and no G4 toxicities. At 12 weeks, analysis of bone markers did not reveal significant biologic trends. At Pg, bone specific alkaline phosphatase and N-telopeptide increased in all pts, less so in pts on the 2000mg arm and in pts who obtained SD at 6m. CTCs increased over time in both arms. Conclusions: Cilengitide was well tolerated. The 2,000 mg arm had a modest but not clinically significant effect so 2nd stage was not pursued. Neither dose level decreased the 6 m PgR. Decreased level of bone markers correlated with a trend towards decreased PgR. The unique study design using a non-Pg endpoint, not acting on PSA changes, and confirming Pg after 1st assessment was feasible. Supported by CTEP, Prostate SPORE Grant P50 CA069568–09, PC051375, Merck KGaA, PC051382, Immunicon. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Johnson & Johnson Merck KGaA

A pilot study investigating maintenance sargramostim in patients with androgen-independent prostate cancer (AIPC) who have maximized their response to chemotherapy: preliminary results

16111 Background: There is no standard of care for AIPC patients (pts) who completed chemotherapy. Most studies report time to progression (TTP) ranging from 3 to 6 months. GM-CSF is an immune-base...

Inhibition of androgen-independent prostate cancer cell growth is enhanced by combination therapy targeting Hedgehog and ErbB signalling

BackgroundProstate cancer is a leading cause of male cancer specific mortality. When cure by radical prostatectomy is not possible the next line of prostate cancer treatment is androgen deprivation. However prolonged androgen deprivation often results in relapse and androgen-independent prostate cancer that is inevitably fatal despite optimal chemotherapy. The Hedgehog signalling pathway has recently been implicated in prostate cancer development and metastasis. EGFR or ErbB2 expression has been also correlated with androgen independence, shorter survival and metastasis.ResultsWe determined that the Hedgehog and ErbB signalling pathways are active in circulating tumour cells isolated from androgen-independent prostate cancer patients and in the androgen-independent prostate cancer cell line LNCaP C4-2B. As a basis for synergistic chemotherapy protocols combinations of the Hedgehog specific inhibitor cyclopamine and the ErbB signalling inhibitors gefitinib or lapatinib were tested in this study. Androgen-independent prostate cancer cell growth was inhibited by a SMO inhibitor (cyclopamine) which blocks Hedgehog signalling and by ErbB inhibitors (gefitinib and lapatinib). The isobologram and combination index method of Chou and Talalay was used to evaluate drug interactions. Synergistic antiproliferation effects were observed when the Hedgehog and ErbB inhibitors were combined.ConclusionAndrogen-independent prostate cancer cell proliferation was associated with activity of the Hedgehog and ErbB signalling pathways. Cyclopamine, gefitinib or lapatinib treatment significantly decreased the proliferation of androgen-independent prostate cancer cells. The Hedgehog pathway therefore represents a promising new therapeutic target in androgen-independent prostate cancer. Synergistic effects were observed when Hedgehog and ErbB inhibitors were used together. This study may have clinical implications for improving the treatment of advanced prostate cancer.

Phase II Study of Ketoconazole Plus Granulocyte-Macrophage Colony-Stimulating Factor for Prostate Cancer: Effect of Extent of Disease on Outcome

The efficacy of ketoconazole plus the immunostimulatory cytokine granulocyte-macrophage colony-stimulating factor was prospectively evaluated in patients with castration resistant prostate cancer with and without metastases. Eligible patients had progressive castration resistant prostate cancer by consensus criteria and had received no prior immunotherapy, chemotherapy or ketoconazole. Patients received 400 mg ketoconazole orally 3 times daily, and 20 mg hydrocortisone orally each morning and 10 mg hydrocortisone orally each evening. Granulocyte-macrophage colony-stimulating factor (250 microg/m2) was administered subcutaneously on days 15 to 28 of each 28-day cycle. Progression was defined as disease progression or toxicity. A total of 49 patients were enrolled, including 37 with radiographically evident metastases and 12 with prostate specific antigen only disease. Median patient age was 68 years (range 52 to 84) and median prostate specific antigen was 23.1 ng/ml (range 5.4 to 306.5). Time to progression, which was the primary study end point, was 9.7 months for all patients. Ten of the 30 treatment failures showed radiographic progression and 6 were due to toxicity, while treatment failure in 14 of 30 patients (47%) consisted only of increasing prostate specific antigen. Median time to progression was 6.9 and 15.4 months in patients with and without metastases, respectively (p = 0.01). Of 48 patients 36 (75%, 95% CI 60-86) experienced a 50% or greater decrease in prostate specific antigen. Four grade 4 events occurred that were unrelated to the study drug. Grade 3 events related to study therapy in more than 1 patient consisted of fatigue in 7 (14%). Combined ketoconazole and granulocyte-macrophage colony-stimulating factor yields a high response rate and it is an option for patients with castration resistant prostate cancer. Time to progression in patients without metastases is significantly longer than in those without metastases.

C-reactive protein as a prognostic marker for men with androgen-independent prostate cancer (AIPC): Results from the ASCENT trial

5074 Background: Concentrations of blood proteins such as PSA, hemoglobin (HGB), and LDH are associated with survival in men with AIPC. We sought to identify additional blood proteins associated with prognosis in chemotherapy-treated AIPC patients. Methods: Baseline plasma samples were stored (-80°C) from 160 patients enrolled in the ASCENT trial, a randomized placebo-controlled phase 2 trial comparing weekly docetaxel plus DN-101, an oral high-dose formulation of calcitriol, to weekly docetaxel. Multiplex immunoassays measured 16 cytokine/chemokine or cardiovascular/inflammation markers including IL-1a, IL-1β, IL-2, IL-6, IL-8, IL-10, TNFa, MCP-1, EGF, VEGF, PAI-1, MMP-9, sE-Selectin, sICAM-1, sVCAM-1 and C-reactive protein (CRP). Cox’s proportional hazard model was used to assess association between baseline biomarkers and survival or skeletal-related event (SRE)-free survival, and logistic regression for PSA Working Group Criteria response. Results: Baseline characteristics were similar to those of the 90 patients without samples, except for age (mean 68.0 vs. 70.6 yrs) and HGB (12.8 vs. 12.2 g/dL). CRP was the only biomarker that significantly predicted shorter overall survival (HR 1.41, 95% CI 1.20–1.65, p &lt; 0.0001). When CRP (continuous) was entered into a multivariate model using 13 baseline variables (including PSA, LDH, alkaline phosphatase, HGB, ECOG Performance Status, age) only elevated CRP remained a significant predictor (p&lt;0.0001) of shorter survival. When categorized as normal (= 8 mg/L) or abnormal (&gt; 8 mg/L), elevated CRP was a significant predictor of shorter survival (HR 2.96 95% CI 1.52–5.77, p = 0.001) as was HGB (p=0.007). Elevated CRP was also associated with a lower probability of PSA response (OR 0.74, 95% CI 0.60–0.92, p = 0.007) and a shorter SRE-free survival (HR 1.30, 95% CI 1.15–1.48, p &lt; 0.0001). Conclusions: Elevated levels of plasma CRP appear to be a strong predictor of poor survival and development of SREs in AIPC patients receiving docetaxel-based therapy. The use of CRP as a risk marker and its potential as a surrogate marker of treatment effect should be prospectively evaluated in future clinical trials in advanced prostate cancer. [Table: see text]

EMD121974 (NSC 707544, cilengitide) in asymptomatic metastatic androgen independent prostate cancer (AIPCa) patients (pts): A randomized trial by the Prostate Cancer Clinical Trials Consortium (NCI 6372)

5137 Background: Integrins avβ3 and avβ5 are essential to PCa metastasis by regulating cell adhesion, migration, invasion and motility. Cilengitide is a potent and selective avβ3 and avβ5 integrin receptor antagonist that in phase I studies has shown clinical activity. Methods: Pts with asymptomatic, metastatic chemo-naive AIPCa with PSA or objective progression, no visceral disease, minimum PSA of 5ng/ml, and adequate organ function were randomized to cilengitide 500 mg or 2,000 mg IV 2X weekly in 6-week cycles, using modified randomized selection design. Disease status was assessed every 12 weeks. The primary end point is objective progression rate (not including PSA) at 6 months. The Simon 2-stage optimal design is used to accrue 53 pts/arm. After first stage (20 pts/arm), accrual continues if ≥ 6 pts have not progressed. If second stage accrual is initiated, at end of study, the better performing arm will be chosen for further study provided at least 18/53 pts in that arm have not progressed. Secondary end points include safety, response rates and correlative measures of cilengitide effect on circulating and bone marrow tumor and endothelial cells and on bone remodeling markers. Results: First stage accrual is complete with 42 pts registered. Median performance status is 0, median age is 71 years (range 52–85), and median PSA is 44ng/ml (range 5–870). Disease progression at registration was defined by PSA in 90%, soft tissue in 36% and bone in 31% of pts. Median number of cilengitide cycles is 3 (range 1–8). To date, 32/42 pts have received ≥ 2 cycles. The most common (&gt;5%) treatment related adverse events (AE): fatigue (38%), constipation (13%), anorexia (10%), leucopenia (8%) and nausea (8%). There were only 3 grade (G) 3 AEs (neutropenia, lymph node pain, lymph NOS) and no G4 AEs. Only 3 pts required dose modification. 25/42 pts were removed from protocol on or before 6 months, 6 pts received therapy for more than 6 months, and 11 are too early to assess. Conclusions: Cilengitide is well tolerated. Final results (efficacy, safety, correlative studies) of the first stage of accrual will be reported. Supported by CTEP, Prostate SPORE Grant P50 CA069568- 09, PC051375, Merck KGaA, PC051382. [Table: see text]