Protein arginine methyltransferase 5 functions as an epigenetic activator of the androgen receptor to promote prostate cancer cell growth

Protein arginine methyltransferase 5 (PRMT5) is an emerging epigenetic enzyme that mainly represses transcription of target genes via symmetric dimethylation of arginine residues on histones H4R3, H3R8 and H2AR3. Accumulating evidence suggests that PRMT5 may function as an oncogene to drive cancer cell growth by epigenetic inactivation of several tumor suppressors. Here, we provide evidence that PRMT5 promotes prostate cancer cell growth by epigenetically activating transcription of the androgen receptor (AR) in prostate cancer cells. Knockdown of PRMT5 or inhibition of PRMT5 by a specific inhibitor reduces the expression of AR and suppresses the growth of multiple AR-positive, but not AR-negative, prostate cancer cells. Significantly, knockdown of PRMT5 in AR-positive LNCaP cells completely suppresses the growth of xenograft tumors in mice. Molecular analysis reveals that PRMT5 binds to the proximal promoter region of the AR gene and contributes mainly to the enriched symmetric dimethylation of H4R3 in the same region. Mechanistically, PRMT5 is recruited to the AR promoter by its interaction with Sp1, the major transcription factor responsible for AR transcription, and forms a complex with Brg1, an ATP-dependent chromatin remodeler, on the proximal promoter region of the AR gene. Furthermore, PRMT5 expression in prostate cancer tissues is significantly higher than that in benign prostatic hyperplasia tissues, and PRMT5 expression correlates positively with AR expression at both the protein and mRNA levels. Taken together, our results identify PRMT5 as a novel epigenetic activator of AR in prostate cancer. Given that inhibiting AR transcriptional activity or androgen synthesis remains the major mechanism of action for most existing anti-androgen agents, our findings also raise an interesting possibility that targeting PRMT5 may represent a novel approach for prostate cancer treatment by eliminating AR expression.

YAP activation protects urothelial cell carcinoma from treatment-induced DNA damage

Current standard of care for muscle-invasive urothelial cell carcinoma (UCC) is surgery along with perioperative platinum-based chemotherapy. UCC is sensitive to cisplatin-based regimens, but acquired resistance eventually occurs, and a subset of tumors is intrinsically resistant. Thus, there is an unmet need for new therapeutic approaches to target chemotherapy-resistant UCC. Yes-associated protein (YAP) is a transcriptional co-activator that has been associated with bladder cancer progression and cisplatin resistance in ovarian cancer. In contrast, YAP has been shown to induce DNA damage associated apoptosis in non-small cell lung carcinoma. However, no data have been reported on the YAP role in UCC chemo-resistance. Thus, we have investigated the potential dichotomous role of YAP in UCC response to chemotherapy utilizing two patient-derived xenograft models recently established. Constitutive expression and activation of YAP inversely correlated with in vitro and in vivo cisplatin sensitivity. YAP overexpression protected while YAP knock-down sensitized UCC cells to chemotherapy and radiation effects via increased accumulation of DNA damage and apoptosis. Furthermore, pharmacological YAP inhibition with verteporfin inhibited tumor cell proliferation and restored sensitivity to cisplatin. In addition, nuclear YAP expression was associated with poor outcome in UCC patients who received perioperative chemotherapy. In conclusion, these results suggest that YAP activation exerts a protective role and represents a pharmacological target to enhance the anti-tumor effects of DNA damaging modalities in the treatment of UCC.

Long-term survival and biomarker correlates of tasquinimod efficacy in a multicenter randomized study of men with minimally symptomatic metastatic castration-resistant prostate cancer

PURPOSE

Tasquinimod (Active Biotech) is an oral immunomodulatory, anti-angiogenic, and anti-metastatic agent that delayed metastatic disease progression in a randomized placebo-controlled phase II trial in men with metastatic castration-resistant prostate cancer (mCRPC). Here, we report long-term survival with biomarker correlates from this trial.

EXPERIMENTAL DESIGN

Two hundred and one (134 tasquinimod and 67 placebo) men with mCRPC were evaluated. Forty-one men randomized to placebo crossed over to tasquinimod. Survival data were collected with a median follow-up time of 37 months. Exploratory biomarker studies at baseline and over time were collected to evaluate potential mechanism-based correlates with tasquinimod efficacy including progression-free survival (PFS) and overall survival (OS).

RESULTS

With 111 mortality events, median OS was 33.4 months for tasquinimod versus 30.4 months for placebo overall, and 34.2 versus 27.1 months in men with bone metastases (n = 136), respectively. Multivariable analysis demonstrated an adjusted HR of 0.52 [95% confidence interval (CI), 0.35-0.78; P = 0.001] for PFS and 0.64 (95% CI, 0.42-0.97; P = 0.034) for OS, favoring tasquinimod. Time-to-symptomatic progression was improved with tasquinimod (P = 0.039, HR = 0.42). Toxicities tended to be mild in nature and improved over time. Biomarker analyses suggested a favorable impact on bone alkaline phosphatase and lactate dehydrogenase (LDH) over time and a transient induction of inflammatory biomarkers, VEGF-A, and thrombospondin-1 levels with tasquinimod. Baseline levels of thrombospondin-1 less than the median were predictive of treatment benefit.

CONCLUSIONS

The survival observed in this trial of men with minimally symptomatic mCRPC suggests that the prolongation in PFS with tasquinimod may lead to a survival advantage in this setting, particularly among men with skeletal metastases, and has a favorable risk:benefit ratio.

Mechanisms of action of tasquinimod on the tumour microenvironment

Tasquinimod is a small molecule with pleiotropic effects on the tumour microenvironment. Tasquinimod inhibits the growth and metastasis of tumour cells in vitro and in vivo. It targets the tumour microenvironment, enhancing the host immune response and inhibiting the angiogenic response. Tasquinimod influences infiltrating myeloid cells in the tumour milieu shifting the balance towards a less immunosuppressive phenotype. Myeloid-derived suppressor cells and tumour-associated macrophages are major components of the immunosuppressive microenvironment and as a result promote tumour growth and favour angiogenesis and metastasis formation. Growing evidence indicates that tasquinimod targets these myeloid cells and modulates local tumour immunity by blocking the interaction between the multifunctional protein S100A9 and its ligands receptor of advanced glycation end products and Toll-like receptor 4. Its anti-angiogenic effects are achieved at least in part through these effects on regulatory myeloid cells and also potentially through inactivating histone deacetylase-4 and reducing expression of hypoxia-inducible factor 1-controlled genes. The aim is to comprehensively review the mode of action of tasquinimod as a novel oral anti-cancer agent. Based on its unique combination of effects, tasquinimod is a novel agent with clinical therapeutic potential in various solid tumours, both alone and as part of rational combination therapy.

A phase I/IIA study of AGS-PSCA for castration-resistant prostate cancer

BACKGROUND

This first-in-human phase I/IIA study was designed to evaluate the safety and pharmacokinetics (PKs) of AGS-PSCA a fully human monoclonal antibody directed to prostate stem cell antigen (PSCA) in progressive castration-resistant prostate cancer.

PATIENTS AND METHODS

Twenty-nine patients were administered infusions of AGS-PSCA (1-40 mg/kg) every 3 weeks for 12 weeks; 18 final patients received a 40-mg/kg loading dose followed by 20-mg/kg repeat doses. Primary end points were safety and PK. Immunogenicity, antitumor activity and circulating tumor cells were also evaluated.

RESULTS

No drug-related serious adverse events were noted. Dose escalation stopped before reaching the maximum tolerated dose as target concentrations were achieved. Drug levels accumulated linearly with dose and the mean terminal half-life was 2-3 weeks across dose levels. The 40-mg/kg loading dose followed by repeated 20-mg/kg doses yielded serum drug concentrations above the projected minimum therapeutic threshold after two to three doses without excessive drug accumulation or toxicity. Significant antitumor effects were not seen.

CONCLUSIONS

A 40-mg/kg loading dose followed by 20-mg/kg infusions every 3 weeks is the recommended phase II dose of AGS-PSCA. PSCA is a promising drug target and studies in prostate and other relevant solid tumors are planned.

Mental disorders in obese patients with and without metabolic syndrome

OBJECTIVE

The authors sought to evaluate lifetime prevalence of mental disorders in patients affected by metabolic syndrome compared with patients affected by central obesity alone.

METHODS

One hundred eighty-six (63.5%) patients affected by central obesity and 107 (36.5%) affected by metabolic syndrome according to ICF criteria were interviewed by means of SCID I and SCID II.

RESULTS

Axis I and axis II lifetime prevalence were respectively 53.8% and 30.1% among patients with central obesity, 50.5% and 28% among patients with metabolic syndrome, differences which were not significant. No statistically significant differences were found between groups as far as each single axis I and II diagnostic category was considered.

CONCLUSION

Metabolic syndrome is not associated with a higher risk of mental disorders compared to central obesity alone.

Phase I study of the histone deacetylase inhibitor entinostat in combination with 13-cis retinoic acid in patients with solid tumours

BACKGROUND

Preclinical studies suggest that histone deacetylase (HDAC) inhibitors may restore tumour sensitivity to retinoids. The objective of this study was to determine the safety, tolerability, and the pharmacokinetic (PK)/pharmacodynamic (PD) profiles of the HDAC inhibitor entinostat in combination with 13-cis retinoic acid (CRA) in patients with solid tumours.

METHODS

Patients with advanced solid tumours were treated with entinostat orally once weekly and with CRA orally twice daily × 3 weeks every 4 weeks. The starting dose for entinostat was 4 mg m(-2) with a fixed dose of CRA at 1 mg kg(-1) per day. Entinostat dose was escalated by 1 mg m(-2) increments. Pharmacokinetic concentrations of entinostat and CRA were determined by LC/MS/MS. Western blot analysis of peripheral blood mononuclear cells and tumour samples were performed to evaluate target inhibition.

RESULTS

A total of 19 patients were enroled. The maximum tolerated dose (MTD) was exceeded at the entinostat 5 mg m(-2) dose level (G3 hyponatremia, neutropenia, and anaemia). Fatigue (G1 or G2) was a common side effect. Entinostat exhibited substantial variability in clearance (147%) and exposure. CRA trough concentrations were consistent with prior reports. No objective responses were observed, however, prolonged stable disease occurred in patients with prostate, pancreatic, and kidney cancer. Data further showed increased tumour histone acetylation and decreased phosphorylated ERK protein expression.

CONCLUSION

The combination of entinostat with CRA was reasonably well tolerated. The recommended phase II doses are entinostat 4 mg m(-2) once weekly and CRA 1 mg kg(-1) per day. Although no tumour responses were seen, further evaluation of this combination is warranted.

MC0553: A phase II safety and efficacy study with the VEGF receptor tyrosine kinase inhibitor pazopanib in patients with metastatic urothelial cancer

259

Background: Vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) are produced by bladder cancer cell lines in vitro and expressed in human tumor tissues. Preclinical studies have also shown that bladder cancer cell lines express VEGF receptor 1 and 2 on their surface membrane. Pazopanib is a vascular endothelial receptor tyrosine kinase inhibitor with anti-angiogenesis and antitumor activity in several preclinical models. A two-stage phase II study was conducted to assess the activity and toxicity profile of pazopanib administered to patients with metastatic, urothelial carcinoma.

Methods: Patients with one prior systemic therapy for recurrent, metastatic urothelial carcinoma were eligible. Patients received pazopanib at a dose of 800 mg orally daily for 4 week cycle.

Results: Nineteen patients were enrolled. Median age was 66 years, with > 89% of patients presenting poorly differentiated bladder cancer. Adverse event data is available on 18 patients. No grade 4 or 5 events have been experienced. Nine patients have experienced 11 grade 3 adverse events of which 7 were deemed at least possibly related to treatment. Most common toxicities were anemia, thrombocytopenia, leucopenia and fatigue. For stage 1, none of the first 16 evaluable patients were deemed success (CR or PR) by the RECIST criteria during the first four 4-week cycles of treatment. Median progression- free survival was 1.9 months. This met the futility stopping rule of interim analysis, and therefore, the trial was recommended to be permanently closed. Correlative studies including measurement of VEGF levels in archived tissues and blood are pending.

Conclusions: Pazopanib did not show activity in urothelial carcinoma patients. The role of anti-VEGF therapies in urothelial carcinoma may need further evaluation in rational combination strategies.

[Table: see text]

Phase II study of tasquinimod in chemotherapy-naive patients with metastatic castrate-resistant prostate cancer (CRPC): Safety and efficacy analysis including subgroups

126

Background: Tasquinimod (TASQ) is an oral quinoline-3-carboxamide derivative that binds to S100A9 and displays anti-angiogenic and anti-tumor activity in prostate cancer (PC) models. In a randomized blinded phase II study, 206 (136 TASQ, 70 placebo [P]) men with metastatic castrate resistant (CRPC) were assigned to TASQ/P once-daily at an initial dose level of 0.25 mg/day escalating to 1.0 mg/day over 4 weeks. The primary endpoint to demonstrate an improvement in PCWG2 criteria-defined progression at 6 months was met and presented at ASCO 2010. This abstract provides an update on safety and efficacy including CRPC subgroups.

Methods: Subgroups of patients based on baseline criteria were investigated for safety using NCI CTC v 3.0 criteria, PK and efficacy.

Results: 201 (134 TASQ, 67 P) pts with a median age of 72.6 years received treatment and were evaluable for efficacy and safety. The updated analysis based on 5 additional PFS events confirmed an improved PFS of 7.6 vs. 3.3 months for pts on TASQ vs. P. Most progression events in both arms were radiological, but more pts progressed on bone scan in the P group. Radiographic PFS was 8.8 vs 4.4 months. Significant PFS improvements were observed in the PCWG2 risk groups with bone metastatic and visceral disease. TASQ treatment led to a transient increase in inflammatory lab markers such as CRP and fibrinogen, as well as asymptomatic increases in amylase/lipase. CRP increase was associated with adverse events (AEs) such as muscle and joint pain, while increased amylase was associated with a lower risk for gastrointestinal AEs. TASQ treatment was associated with anaemia, but did not affect CV risk factors such as hypertension or QTc prolongation, and the rate of composite cardiac events was acceptably low. Clearance of TASQ is decreased with age (1.4 % per year) and patients over 80 often required dose reduction due to increased exposure and toxicities.

Conclusions: TASQ improved PFS in men with metastatic CRPC. Side effects are manageable and seem to correlate with laboratory markers. Individualized dosing based on tolerability is recommended and a phase III placebo-controlled study is being initiated.

[Table: see text]

Effect of angiotenstin system inhibitors (ASIs) on the outcome of sunitinib treatment (tx) in patients (pts) with metastatic renal cell carcinoma (mRCC)

317

Background: The VEGFR inhibitor sunitinib is a standard tx for mRCC. ASIs include angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs). ASIs are used in the tx of hypertension (HTN), kidney disease, and heart failure. Preclinical and clinical studies in several cancer types have shown that they may inhibit tumor growth. Their effect on the outcome of sunitinib in mRCC is poorly defined. Aims: to study the effect of ASIs on the outcome sunitinib tx for mRCC.

Methods: We performed a retrospective study of an unselected cohort of pts with mRCC, who were treated with 50 mg of oral sunitinib in cycles of 4 weeks followed by 2 weeks of rest. Pts were divided into 2 groups: (1) ASIs users and (2) ASIs naive. The effect of ASIs use on objective response, time to progression (TTP), and overall survival (OS), was tested with adjustment of other known confounding risk factors using a chisquare test and partial likelihood test from cox model.

Results: Between 2004–2010, 124 pts with mRCC were treated with sunitinib. There were 44 ASIs users (group 1) and 80 nonusers (group 2). With regard to sunitinib tx initiation time, 39 users started ASIs before, 3 within 1 month, and 2 after 5 months. The groups were balanced regarding the following known clinical prognostic factors: past nephrectomy, RCC histology, time from diagnosis to tx, ≥ 2 metastatic sites, lung/liver/bone metastasis, ECOG performance status, Hb level, corrected ca > 10 mg/dL, platelets count, prior cytokines/ targeted tx, sunitinib induced HTN, % pts that had dose reduction/tx interruption, and mean dose/cycle. Objective response in group 1 vs. 2 was partial response (PR) 48% vs 38% (p=0.24), stable disease (SD) 38% both, and progressive disease (PD) 14% vs. 24% (p=0.19). Median TTP was 12 vs. 6 ms (HR 0.635 in ASIs users, p=0.034). Median OS was 25 vs. 22 ms (p=0.3).

Conclusions: ASIs may improve the outcome of pts with mRCC that are treated with sunitinib. This should be investigated prospectively, and if validated, applied in clinical practice and clinical trials.

No significant financial relationships to disclose.

A randomized double blind phase I-II study to determine the tolerability/efficacy of two different doses of lenalidomide (L), CC- 5013, in biochemically relapsed (BR) prostate cancer (PC) patients (pts) (M0) after local treatment (LT)

5130

Background: BR following LT is common in PC with no defined standard treatment. Lenalidomide (L) is an immunomodulatory agent with anti-angiogenic and direct antitumor effects. Methods: This trial was designed to evaluate a dose-effect relationship of L in BR PC. Pts were randomized to either 5 or 25 mg/day(d), PO, d 1–21 (28-d cycles); then stratified by PSADT (< 3, 3–8.9, ≥ 9 mos), LT and prior ADT. Eligible pts had: rising PSA (≥1 ng/mL), M0 disease, testosterone > 150 ng/mL, adequate bone marrow, renal, and hepatic function. Baseline and Q 2 mos PSA's were processed after Q 6 mos of L, along with CT and bone scan. Toxicity exams were Q mo. Primary endpoints are safety and progression after 6 mo of L (defined by a confirmed ↑ in PSA > 25% over the baseline value or mets). Secondary endpoints are changes of slopes in PSA related to pharmacokinetics (pk). A sample size of 30 pts/arm provides an 85% power to detect a PSA progression rate of 40% (compared to 80% predicted ) with a Type I error = 0.05 (Fishers exact test). Results: 59 pts were entered July 20, 2006-December 31, 2008. Pooled data from the 2 arms: median: age 64 (50–81), ECOG PS 0, baseline PSA 9.3 ng/ml (1.3–92.8 ng/ml). 16 pts had PSADT <3 mos, 26 from 3–8.9 mos, and 17 ≥ 9 mos. Median: F/U on all 59 pts is 351 + d (9 +-887+d); # cycles = 6 (1–30). Thus far, 44/59 pts completed 6 cycles of L (1 had PD, 6 stopped L due to toxicity, 8 too early). 22 /44 who completed 6 mos of L remained on L > 6 mos ( 7+-30+ mos); including 7 pts ≥ 24 mos. Of 44 pts, blinded evaluation of PSA's at 6 mos: 4 pts had ≥ 50% ↓, 22 had stable PSA,17 had PD, 1 too early . Rash was DLT. Other Gr toxicities: appendicitis, abd pain, neck pain, venous thrombolic disease, fatigue, pruritus. Conclusions: Preliminary data prior to unblinding the study treatment arms, from pooled data, suggest that L may be administered > 6 mos with acceptable toxicity, and is associated with PSA declines and long term stabilization in pts with BR. Supported by a grant from Celgene Corporation. Data coordination infrastructure is supported by the Prostate Cancer Foundation and The James Stine research fund.

[Table: see text]

Phase II study of 2-methoxyestradiol NanoCrystal dispersion (2ME2) alone and in combination with sunitinib (SU) in patients with metastatic renal cell carcinoma (mRCC) progressing on SU

e16116

Background: Panzem NCD (2ME2) is a non-estrogenic derivative of estradiol with antiproliferative and antiangiogenic activity that downregulates HIF-1α. One mechanism of VEGFR TKI failure may be upregulation of HIF-1α. We hypothesized that 2ME2 may have single-agent activity in pts who previously progressed on SU and that addition of 2ME2 may restore response in pts progressing on SU. Methods: Pts with clear cell mRCC who had previously received or were currently receiving SU with disease progression were eligible. Pts who had previously received SU were treated with 2ME2 alone (arm A). Pts currently on SU continued on the 4:2 schedule, with the addition of 2ME2 (arm B). All pts received 2ME2 at 1,500 mg PO TID, repeated in 6 wk cycles. The primary endpoint was objective response (OR) rate by RECIST. An exploratory endpoint was metabolic response on FDG-PET. Simon optimal 2-stage design was used with plans to enroll 21 pts/arm, and if activity was seen to continue enrollment for a total of 41 pts/arm. Results: 17 pts were enrolled (A: 10; B: 7). Median number of cycles on study was 1 (range <1 to 5). A pt remains on study in cycle 8. Adverse events (AE) of grade 3 or greater occurred in 4 pts (29%). Most frequent AE were: fatigue (71%), diarrhea (50%), dysgeusia (29%), anemia or decreased hemoglobin (29%), and anorexia (21%). Reasons for treatment discontinuation include: disease progression (7), pt/doctor discretion (3), AE (3), and noncompliance (1). No ORs by RECIST were seen. Conclusions: 2ME2 appears to have some single-agent activity, with an MR in a pt removed from study due to AE and a metabolic PR (ΔSUVmax -84%) in a pt with SD by RECIST. With 6/17 pts discontinuing therapy before meeting any OR endpoint, 2ME2 was not tolerable in this population. The study was closed to accrual knowing that a more promising 2ME2 analog is currently under development for oncologic use. The rationale to target HIF-1α after (and during) SU therapy remains of interest. This study design provides a unique way to assess both single-agent and rational combination strategies in pts with mRCC and should be utilized with other agents to seek evidence for clinical activity.

[Table: see text]

A phase II trial of rapid androgen cycling and docetaxel (Doc) in prostate cancer patients with a rising prostate-specific antigen (PSA) in the noncastrate state

5004

Introduction: Prostate cancer patients in the noncastrate state with a rapidly rising PSA are at high-risk for cancer-specific mortality. Since hormonal therapy alone is not curative, we have explored the use of rapid androgen cycling with Doc to recruit proliferating cells into successive waves of apoptosis, thereby shifting the treatment outcome for these patients from palliation to cure. Methods: Patients with noncastrate levels of testosterone (T), a rising PSA ± metastases, and = 6 months of prior hormones were eligible. Cohort 1: Six 4- week cycles of monthly leuprolide and Doc (75 mg/m2), with 7 days of topical T repletion (AndroGel 1% 5G) prior to each treatment. Cohort 2: Nine 3-week cycles of Doc (70 mg/m2), with 3 days of T repletion per cycle and 3-month depot leuprolide on day 1 of cycles 1, 5, and 9. The primary endpoint was the proportion of patients with a treatment-specific undetectable PSA at 6 and 18 months defined as: = 0.05 after surgery, = 0.5 after radiation, or = 2.0ng/ml with untreated disease. This is based on the premise that an undetectable PSA is a prerequisite to, but no guarantee of cure. Results: There were no increases in sequential PSA peaks or troughs and 100 out of 102 patients completed the planned 6 months of chemohormonal treatment. Twenty three of 62 (37%) patients in cohort 1, and 25 of 38 (66%) patients in cohort 2 achieved the primary endpoint of a treatment-specific undetectable PSA at 6 months. At 12 months, no patient in cohort 1 had maintained an undetectable PSA in the setting of a noncastrate T level; whereas, 8 of 15 (53%) patients in cohort 2 have achieved the endpoint at 12 months. Toxicities were similar to those observed with Doc and hormonal therapy administered separately. Conclusions: Rapid androgen cycling with docetaxel is feasible, and can induce successive declines in PSA peaks and troughs. The more dose-dense cohort 2 schedule of 21-day Doc administration for 9 cycles, along with reduced exposure to androgen repletion from 7 to 3 days, has resulted in a higher proportion of undetectable PSA outcomes at both 6 (66% vs. 37%) and 12 (53% vs. 0%) months. Complete PSA outcomes for cohort 2 at 12 and 18 months are still pending. Supported by Sanofi-Aventis, CA-05816, and PepsiCo.

No significant financial relationships to disclose.

Phase I trial of docetaxel (D) plus samarium153 (Sm 153) in patients (pts) with hormone refractory prostate cancer (HRPC)

15547

Background: Bone targeted approaches hold great promise for improving outcomes in HRPC. Docetaxel (D) and samarium 153 (Sm153 ) have individually demonstrated a clinical benefit and preclinical data strongly support biological synergism in HRPC. Preclinical data suggests that 24 hour after a dose of D, there is maximum G2M arrest. This results in the accumulation of cells in the most radiosensitive phase of the cell cycle. This phase I trial was designed to evaluate toxicity and preliminary efficacy of combined D and Sm153 administered sequentially in advanced HRPC. Methods: HRPC pts progressing after anti-androgen withdrawal; = 2 prior chemotherapy regimens; acceptable bone marrow, renal and hepatic function were eligible. Planned D treatment in 4 cohorts (N=3/cohort) includes: Cohort 1: D 50mg/m2 IV on days 1, 22, 91, and 112; cohort 2: D 75mg/m2 IV on days 1 and 22 followed by 50mg/m2 IV on days 91 and 112; cohort 3: D 75mg/m2 IV on days 1 and 22 followed by 75mg/m2 IV on days 91 and 112; cohort 4: D 75 mg/m2 IV on days 1, 22, 42, 91, 112, and 133. Sm 153 (1.0 mi/Kg) is administered IV days 2 and 92 of each cycle. Cycles are repeated Q 12 wks (max 2 cycles). The endpoint for this trial is dose limiting toxicity and maximal tolerated dose. Results: From 5/11/05 - 1/7/07 ten pts were enrolled. Median: age 69.5 yrs (range 58–76), ECOG performance status 1 (range 0–1), baseline PSA 76.65 ng/ml (range 9.6–1064 ng/ml ), prior hormonal manipulations 3 (range1–6). Three pts had prior taxotere and 3 pts had prior palliative RT. All had bone metastases and 2 also had soft tissue disease. Five pts completed 2 cycles of treatment as planned. Five pts had 1 cycle (one pt is on treatment, 3 pts had PD and 1 had prolonged grade 1 thrombocytopenia =3 wks). Nine of 10 pts had reversible grade 3 / 4 neutropenia (1 pt had reversible episode of neutropenia with fever). Seven of 7 symptomatic pts had improvement in pain. Four of 10 of pts had a 50 % decline in PSA level lasting = 4 weeks; no soft tissue disease responses. Conclusions: Our preliminary data suggest that Q 3 wk D and Q 3 month Sm153 may be administered simultaneously at full doses in extensively pretreated HRPC pts, with acceptable toxicity and significant activity. This study is supported by a grant from sanofi- aventis and Sm153 is provided by Cytogen.

No significant financial relationships to disclose.

Randomized phase II study of docetaxel with or without DMXAA (AS1404) in hormone-refractory metastatic prostate cancer (HRMPC)

5115

Background: DMXAA (AS1404) is a small-molecule agent that disrupts tumor vasculature. Combination of DMXAA with taxanes produces synergistic inhibition of tumor growth in animal models. A randomized phase II study in non-small cell lung cancer reported a substantial survival benefit when DMXAA was added to paclitaxel-based chemotherapy. This randomized phase II study examined the effect of adding DMXAA to docetaxel in HRMPC. Methods: Patients had progressive metastatic, androgen-independent, histologically confirmed prostate adenocarcinoma previously untreated with cytotoxics. Patients were randomized 1:1 to receive docetaxel (75 mg/m2) ± DMXAA (1,200 mg/m2) every 21 days for up to 10 cycles. Efficacy endpoints were prostate-specific antigen (PSA) response rate, objective response rate, time to tumor progression, duration of response and disease stabilization, time to PSA progression, and median and 1-year survival. Results: 74 patients were randomized: 34 to DMXAA plus docetaxel (DMXAA arm) and 40 to docetaxel alone (control arm). Median baseline PSA values were 83 ng/ml (range 6–3574 ng/ml) in the DMXAA arm and 87 ng/ml (range 1–570 ng/ml) in the control arm. PSA response data are available from 64 patients (see table ). Latest safety data show a similar number of serious adverse events reported across the treatment groups with 15 and 19 in the DMXAA and control arms, respectively. Conclusions: Addition of DMXAA to standard-dose docetaxel was well tolerated and the combination produced a substantially higher PSA response rate than docetaxel alone. DMXAA demonstrates promising activity in this patient population.

[Table: see text]

[Table: see text]

A phase II trial of 17-allylamino-17-demethoxygeldanamycin (17-AAG) in patients with hormone-refractory metastatic prostate cancer

15553

Background: 17-Allylamino-17-Demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin antibiotic with anti- proliferative activity in several mouse xenograft models including prostate cancer models. Serum IL-6, IL-8, and maspin are potentially important markers of prostate cancer biology. Methods: Patients (pts) with metastatic, hormone-refractory prostate cancer progressing on at least one prior systemic therapy with rising PSA were eligible. All pts received 17-AAG at a dose of 300 mg/m2 IV weekly for three out of four weeks. Primary objective was to assess the PSA response (50% decrease in PSA). Secondary objectives included Adverse Events (AEs) and correlative serum markers including IL-6, IL-8 and maspin levels. A Simon two-stage design required a total of 25 pts with early termination if < 2 responses occurred among the 1st 16 eligible patients. Results: Seventeen pts were enrolled of which 15 were deemed eligible. Median age was 68 and median PSA was 252 ng/mL. Pts received 17-AAG for a median number of 2 cycles. No pt had a PSA response. No grade 4/5 AEs occurred. Grade 3 AEs included fatigue (4 pts), lymphopenia (2 pts) and back pain (2 pts). The median PSA progression free survival was 1.8 months (95% CI: 1.3–3.4 months). The six-month overall survival was 61% (95% CI: 37%-100%). Due to the lack of PSA response, accrual was stopped per study design. At day 15, the median IL-6 and IL-8 increase from baseline was 0.4 pg/ml (p=0.57) and 3 pg/ml (p=0.73), respectively. Maspin levels had day 15 increase of 6-fold (p=0.44). At treatment failure (TF), the median IL-6 increase from baseline was 4.47 pg/ml (p=0.03) and IL-8 decrease was 1.8 pg/ml (p=0.31). Maspin levels had a 29-fold increase at TF (p=0.09). Conclusions: 17-AAG did not show any activity with regards to PSA response. Serum IL-6 was significantly increased at the time of TF. Further evaluation of 17-AAG at a dose of 300 mg/m2 IV weekly in this patient population is not warranted.

No significant financial relationships to disclose.

Phase II study of single-agent vinflunine in platinum-refractory transitional cell carcinoma of the urothelium (TCCU)

15543

Background: Vinflunine (VFL) is a new microtubule inhibitor of the vinca alkaloid class with clinical activity in TCCU (S. Culine, BJC 2006). This trial was conducted to define VFL activity in platinum-refractory TCCU patients (pts). Methods: Multicenter, single-arm study. Primary endpoint: Objective response rate (Independent Review; WHO criteria). Planned sample size: 150 pts. Main pt eligibility: at least one measurable lesion; documented progression within 12 months of last dose of platinum-containing regimen; calculated creatinine clearance (Cr Cl) = 20 mL/min. VFL 320 mg/m2 IV infusion over 20 minutes was administered every 3 weeks. In pts with poor performance status, prior pelvic irradiation, or renal impairment (Cr Cl 20–60 mL/min), initial dose (ID) was 280 mg/m2, escalated to 320 mg/m2 if well tolerated. Results: Enrollment of 150 pts complete. Baseline pt characteristics (first 118 pts treated): Gender: male 78%, female 22%. Median age: 66 years (range 40–83). Renal impairment: 32%. Prior chemotherapy: cisplatin: 69%; carboplatin: 47%, gemcitabine: 94%. Total of 402 VFL cycles administered (range: 1–12). 320 mg/m2 ID: 35 pts; 280 mg/m2 ID: 83 pts. Main toxicity was hematologic (Grade (G) 3/4): neutropenia: 19%/37%; thrombocytopenia: 3%/0%; anemia: 13%/0%; febrile neutropenia: 320 mg/m2 ID: 5 pts; 280 mg/m2 ID: 3 pts. Main non-hematologic toxicities: constipation: 320 mg/m2 ID: 63% (G3/4: 14%/3%); 280 mg/m2 ID: 59% (G3/4: 12%/1%); fatigue: 320 mg/m2 ID: 43% (G3/4: 6%/0%); 280 mg/m2 ID: 35% (G3/4: 7%/0%). Severe diarrhea or vomiting was infrequent. No G3/4 peripheral neuropathy was noted. Responses have been observed by the investigators, but independent review is on-going. Conclusions: VFL has a manageable toxicity profile in pts with platinum-refractory TCCU. Independently reviewed response rate and other efficacy endpoints of the entire cohort will be presented.

No significant financial relationships to disclose.

A phase II evaluation of imatinib mesylate (G) in stage M0 prostate cancer (PC) patients (pts) on hormonal therapy (HT) with evidence of biochemical relapse

14612

Background: Imatinib mesylate (Gleevec, G) is a potent inhibitor of the tyrosine kinases and other signaling mediated events. Preclinical models suggest that G inhibits platelet derived growth factor (PDGF) and stem cell factor (SCF) which are important for prostate cancer growth. This trial was designed to evaluate the safety and efficacy of G in PCA pts on HT with stage M0 disease. Methods: Eligible PCA pts included: stage M0 disease with rising PSA levels while on hormonal therapy, no prior chemotherapy. Planned treatment included G 400 mg PO BID given up to a maximum of 12 months. The statistical endpoint for this trial was the% of pts with a ↓ in prostate specific antigen (PSA) ≥ 50% lasting ≥ 4 wks. A 2 stage trial was designed where the study would terminate if the% of pts meeting the endpoint was not convincingly > 30% with 5% chance for error. Pts with a > 50% rise in PSA from baseline were removed from study. Follow-up included monthly toxicities and PSA (specimens frozen/stored until completion of each 3 months of therapy). Results: From 10/1/02–10/11/04, nine pts were enrolled. Pt characteristics included median: age of 67 years (range 52–80), ECOG performance status of 0 (range 0–1), baseline PSA of 29.6 ng/ml (range 2.69–39.52), # prior hormonal manipulations of 3 (1–5). Prior local therapies included: 1 status post (s/p) RP alone, 2 s/p RT alone, 2 s/p neoadjuvant HT plus RP, 2 s/p neoadjuvant HT plus RT. Two pts had no prior local therapy. Two pts had prior salvage RT, 1 had prior palliative RT. Eight of 9 pts evaluable for response and toxicity. One patient never received treatment. None of the pts had a decline 50% decline in PSA level lasting ≥ 4 weeks. Three of 8 pts (38%) had rapid increases in PSA and 4/8 pts (50%) developed metastatic disease after 3 months of therapy. Only one pt completed 12 months of planned therapy. Grade 3/4 toxicities included: fatigue (25%), rash (25%), arthralgias (12.5%), peripheral edema (25%), depression (12.5%), necessitating dose delays and/or discontinuation of G in 4/8 pts (50%). Conclusions: These data suggest significant toxicity and low clinical benefit. Further evaluation of Gleevec in this pt population is not warranted.

No significant financial relationships to disclose.

Phase 1 pharmacokinetic and pharmacodynamic study of the histone deacetylase inhibitor MS-275 in combination with 13-cis retinoic acid in patients with advanced solid tumors

3055

Background: Preclinical studies suggest that histone deacetylase (HDAC) inhibitors may restore tumor sensitivity to retinoids. The objective of this study was to determine the maximum-tolerated dose (MTD), the dose-limiting toxicity (DLT), and the pharmacokinetic (PK)/pharmacodynamic (PD) profiles of the HDAC inhibitor MS-275 in combination with 13-cis retinoic acid (CRA). Methods: Patients (pts) with advanced solid tumors were treated with MS-275 orally once weekly and CRA orally twice daily x 3 weeks every 4 weeks. The starting dose for MS-275 was 4 mg/m2 and the dose was escalated based on toxicity assessments. The fixed dose for CRA was 1 mg/kg/day. PK concentrations of MS-275 and CRA were determined by LC/MS/MS. Western Blot analysis on peripheral-blood mononuclear cells (PBMCs) and tumor samples (when feasible) were performed to evaluate target inhibition. Results: To date thirteen pts have been enrolled. Tumor types include prostate (4 pts), bladder and renal cell (2 pts), and others. The MTD was exceeded at the 5 mg/m2 dose level (G3 hyponatremia, neutropenia and anemia). Fatigue (G1 or G2) is a common side effect. MS-275 peak concentrations were 141.6±75.7ng/mL at 4mg/m2 and 139.5±30.9 ng/mL at 5mg/m2. MS-275 half-life and clearance were 108.2±47.9h and 9.4±6.0L/h/m2, which is consistent with prior reports for MS-275 as single agent. Median CRA steady-state trough levels were 182.4 ng/mL. The MTD was 4 mg/m2 MS-275 and 1 mg/kg CRA. Five pts remained on treatment for ≥ 4 months including pts with prostate cancer (3), pancreatic cancer (6 months) and a pt with renal cell carcinoma (12 months) who presented a partial response in the lungs. Histones isolated from PBMCs showed transient but consistent protein acetylation post-therapy. Tumor biopsy of a liver lesion from prostate carcinoma revealed post-therapy induced histone acetylation and decreased phosphorylated ERK and STAT3 protein expression consistent with HDAC inhibitory activity. Conclusions: Combination of MS-275 with CRA is reasonably well tolerated and 4 mg/m2 is the Phase II recommended dose for MS-275 in combination with CRA. Tumor response and PD data suggest clinical and biological activity for this combination strategy.

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Phase I study of isotype-selective histone deacetylase (HDAC) inhibitor MGCD0103 given as three-times weekly oral dose in patients (pts) with advanced solid tumors

3007

Background: MGCD0103 is a novel isotype-selective inhibitor of human HDACs. Deacetylation of histones by HDACs is postulated to inactivate tumor suppressor genes leading to neoplastic transformation. Inhibition of these enzymes might restore normal growth control. Methods: A phase I trial of MGCD0103, given as a three-times weekly oral dose 2 out of every 3 weeks, has been performed in pts with advanced solid tumors. Main endpoints are safety, tolerability, pharmacokinetics (PK), pharmacodynamic (PD) assessments of HDAC activity and histone acetylation status in buffy coat white cells. Results: Five dose levels have been evaluated (mg/m2): 12.5, 20, 27, 36, and 45. As of January, 2006, 28 pts have been enrolled with the following demographics: M:F = 18:10; median age (range) = 60 (29–75); ECOG 0:1:2 = 9:13:1 (n = 23); primary tumor sites: colorectal (8), renal (5), lung (4), others (11); prior chemotherapy, radiotherapy, immunotherapy were given to 22, 12 and 2 pts, respectively (n=23). A total of 62 cycles have been administered, with median = 2 and range=1–7 cycles. MGCD0103 has been well tolerated; most common AEs (23 pts): grade 1–3 fatigue (91% of pts), grade 1–2 nausea and vomiting (70 and 48%), anorexia (26%), constipation (39%). Disease stabilization > 2 cycles has been observed in 3 renal cell cancer pts (4, 6, and 7 cycles) and 1 colorectal cancer pt (4 cycles). Preliminary PK analyses demonstrated intra-pt PK variability, however co-administration of acidic carbonated beverage (protocol amendment) appears to reduce variability without altering average Cmax or AUC (0–24) comparing Day 1 with Day 14. There was little accumulation or decrease in concentrations with extended dosing, and t1/2 was dose-independent at 7.7–11.3 hr. (±0.6–1.6). PD data reveal dose-dependent maximal inhibition of HDAC activity in patients co-administered an acidic beverage. Conclusions: At doses evaluated MGCD0103 appears tolerated and exhibits favourable PK and PD.

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Population pharmacokinetics (PK) of the vascular-disrupting agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in cancer patients

13076

Background: DMXAA (AS1404) is a small-molecule vascular-disrupting agent that selectively disrupts established tumor blood vessels. It is being evaluated in phase II trials in combination with cytotoxics. DMXAA is extensively metabolized, predominantly by UDP-glucuronosyltransferase (UGT) 2B7 and 1A9, and exhibits concentration-dependent protein binding. The study aim was to develop a population PK model for DMXAA and to examine covariates influencing drug disposition. Methods: 3,050 DMXAA total plasma concentrations were measured in 124 cancer patients receiving DMXAA monotherapy as a 20-min iv infusion weekly or every three weeks at doses from 6 to 4900 mg/m2 in 3 phase I trials. PK models were fitted to the data from all patients simultaneously using the program NONMEM. Potential covariates including age, body weight, height, body surface area (BSA), sex, and liver and kidney function tests were screened with general additive model analysis and tested in the PK model. Results: DMXAA concentration-time profiles after multiple-dose administration were well described by a 3-compartment model with saturable elimination (Michaelis-Menten kinetic) from the central compartment. BSA and sex were significant covariates on the volume of distribution of the central compartment (V1) and the maximum elimination capacity (Vm), respectively, accounting for 10 and 12% of interindividual variation (IIV) in these parameters. Population estimates for Vm, Km (concentration at which half-maximal elimination rate is achieved), and V1 were 122 × (1 + 0.502 × (2-SEX)) (μM/h) [females had lower Vm than males; SEX = 1 for males, 2 for females], 103 μM, and 8.15 × (BSA/1.8)0.69 (L), respectively. In the final model, IIV in Vm was 52%. Conclusions: DMXAA plasma disposition is characterized by a saturable elimination process. BSA-guided dosing for DMXAA is important. Evaluation of other covariates that reflect drug glucuronidation (e.g., UGT polymorphisms) may account for a greater fraction of the substantial unexplained PK variability. The population PK model will aid development of limited PK sampling strategies and investigation of PK-pharmacodynamic relationships in further trials.

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