Abstract CT302: Pharmacokinetics (PK) and safety of ARN-509 with abiraterone acetate (AA) and prednisone (P) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)

Background: ARN-509 and AA target the androgen axis via different mechanisms and may have complementary activity in mCRPC. ARN-509, a potent and selective androgen receptor (AR) antagonist, inhibits AR nuclear translocation and DNA binding without significant AR agonist properties (Clegg et al. Cancer Res. 2012). AA is the prodrug of abiraterone, which directly inhibits androgen biosynthesis. No overlapping toxicities are expected for the combination. This ongoing phase Ib study evaluates the potential PK drug-drug interaction and safety of ARN-509 in combination with AA + P.

Methods: Pts had progressive mCRPC and ECOG score ≤ 2. Pts received AA (1000 mg/d) + P (5 mg BID) beginning on Cycle 1 Day 1 (C1D1) with the addition of ARN-509 (240 mg/d) on C1D8 in 28-day treatment cycles until disease progression or toxicity. Serial blood samples for PK analysis were collected on C1D7 and C2D8 for abiraterone analysis and on C2D8 for ARN-509 analysis. Primary objective: evaluate effect of ARN-509 on abiraterone PK. Secondary objective: evaluate safety of ARN-509 in combination with AA + P.

Results: As of November 21, 2014, 28 pts have been enrolled. At baseline, the median age was 70 years (range: 49-83); median prostate-specific antigen was 56.8 μg/L (range: 4.1-2597.0 μg/L); bone, nodal, and visceral disease were present in 24 (86%), 17 (61%), and 8 (29%) pts; and 13 (46%) pts were pretreated with docetaxel, 11 (39%) with AA, and 12 (43%) with enzalutamide. 9 pts thus far completed 1 cycle, 6 completed 2 cycles, and 4 completed 3 cycles. 26 pts are continuing therapy. 10 pts were evaluable for PK assessment and 28 pts were evaluable for safety assessment. Most drug-related adverse events (AEs) were grade 1-2, and included fatigue (n = 5), diarrhea (n = 3), dysgeusia (n = 3), vomiting (n = 4), abdominal pain (n = 2), anorexia (n = 3), dyspepsia (n = 2), rash (n = 2) and nausea (n = 3). Grade 3 drug-related AEs included hyponatremia (n = 1), fatigue (n = 1), and increased alanine aminotransferase (n = 1), and were managed by drug interruption and supportive measures. Interim data indicate a small reduction in abiraterone PK exposure when AA + P is coadministered with ARN-509. PK of ARN-509 were consistent with historical data when ARN-509 was given as monotherapy.

Conclusions: This ongoing phase Ib study (NCT02123758) indicates no clinically significant PK interaction between ARN-509 and AA + P. The combination is well tolerated in pts with mCRPC; interim AE data were consistent with those seen in the AA + P phase III trials (Fizazi et al. Lancet Oncol. 2012; Ryan et al. NEJM. 2013). These preliminary results justify further evaluation of the safety and efficacy of ARN-509 in combination with AA + P for mCRPC.

Citation Format: Edwin M. Posadas, Kim N. Chi, Ronald de Wit, Maja JA de Jonge, Gerhardt Attard, Terence Friedlander, Margaret Yu, Peter Hellemans, Caly Chien, Charlene Abrams, Martha Gonzalez, Géralyn C. Trudel, Vijay Chauhan, Fred Saad. Pharmacokinetics (PK) and safety of ARN-509 with abiraterone acetate (AA) and prednisone (P) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT302. doi:10.1158/1538-7445.AM2015-CT302

Subclassification of prostate cancer circulating tumor cells by nuclear size reveals very small nuclear circulating tumor cells in patients with visceral metastases

BACKGROUND

Although enumeration of circulating tumor cells (CTCs) has shown some clinical value, the pool of CTCs contains a mixture of cells that contains additional information that can be extracted. The authors subclassified CTCs by shape features focusing on nuclear size and related this with clinical information.

METHODS

A total of 148 blood samples were obtained from 57 patients with prostate cancer across the spectrum of metastatic states: no metastasis, nonvisceral metastasis, and visceral metastasis. CTCs captured and enumerated on NanoVelcro Chips (CytoLumina, Los Angeles, Calif) were subjected to pathologic review including nuclear size. The distribution of nuclear size was analyzed using a Gaussian mixture model. Correlations were made between CTC subpopulations and metastatic status.

RESULTS

Statistical modeling of nuclear size distribution revealed 3 distinct subpopulations: large nuclear CTCs, small nuclear CTCs, and very small nuclear CTCs (vsnCTCs). Small nuclear CTCs and vsnCTC identified those patients with metastatic disease. However, vsnCTC counts alone were found to be elevated in patients with visceral metastases when compared with those without (0.36 ± 0.69 vs 1.95 ± 3.77 cells/mL blood; P<.001). Serial enumeration studies suggested the emergence of vsnCTCs occurred before the detection of visceral metastases.

CONCLUSIONS

There are morphologic subsets of CTCs that can be identified by fundamental pathologic approaches, such as nuclear size measurement. The results of this observational study strongly suggest that CTCs contain relevant information regarding disease status. In particular, the detection of vsnCTCs was found to be correlated with the presence of visceral metastases and should be formally explored as a putative blood-borne biomarker to identify patients at risk of developing this clinical evolution of prostate cancer.

A phase Ib dose-escalation study of TRC105 (anti-endoglin antibody) in combination with axitinib in patients with metastatic renal cell carcinoma

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Background: Resistance to VEGF-targeted therapy is a major challenge in contemporary treatment of metastatic renal cell carcinoma (mRCC), and endoglin (CD105) activation may be an important mechanism leading to resistance. Endoglin is an essential angiogenic receptor expressed on proliferating tumor vessels and mRCC cancer stem cells that is upregulated following VEGF inhibition. TRC105 is an anti-endoglin monoclonal antibody that potentiates bevacizumab (Bev) and VEGF receptor tyrosine kinase inhibitors (VEGFR TKI) in preclinical models. Methods: Heavily-pretreated mRCC pts with ECOG PS 0-1, and acceptable organ function were treated with TRC105 weekly (8 mg/kg and then 10 mg/kg) in combination with axitinib (initially at 5 mg PO BID and then escalated per patient tolerance to a maximum of 10 mg PO BID). Results: Eighteen mRCC pts (median age=61.5; M:F 16:2; median number of prior therapies=3, including >1 VEGFR TKI, clear cell=13, prior axitinib allowed) were treated. TRC105 dose escalation proceeded from 8 mg/kg (n=3) to 10 mg/kg (n=15) without dose limiting toxicity. Low grade AEs characteristic of each drug were not increased in frequency or severity at the recommended phase 2 doses of the two drugs. Three pts (18%) were PR by RECIST and 8 of 17 pts (47%) exhibited >10% tumor reduction. Median PFS is not mature and is at least 5.8 months in the overall population and at least 5.9 months in ccRCC pts. The single patient who progressed on axitinib immediately prior to study entry remains progression free at month 5 with minor tumor regression. Conclusions: TRC105 at 8 and 10 mg/kg was well tolerated with axitinib in mRCC pts with signs of activity. A multicenter randomized phase II trial of axitinib +/- TRC105 is accruing at this time. Clinical trial information: NCT01806064.

A phase II study of ixabepilone (BMS-247550) in metastatic renal-cell carcinoma

INTRODUCTION

Ixabepilone (BMS-247550) is a semi-synthetic analog of epothilone B that has been characterized as a microtubule stabilizing agent with a mechanism of action distinct from taxanes. Suggestion of activity in renal cell carcinoma (RCC) has been seen in early clinical studies.

METHODS

Eligible patients had metastatic RCC as well as ECOG performance status 0-2 and normal organ function. Patients received ixabepilone at a dose of 40 mg/m2 intravenously over three hours every 21 days. There was no restriction on RCC histology or prior treatment type, but prior treatment with tubule inhibitors was not allowed. The primary endpoint was RECIST defined response and radiographic evaluations were performed every three cycles. Toxicity evaluations utilized CTCAE v3.0 and were performed every cycle. Using a Simon two-stage optimal design with alpha = 0.1, beta = 0.1, a null hypothesized response rate of 0.05 and an alternative response rate of 0.2, an initial 12 patients were to be accrued with full accrual of 37 patients if at least one response were observed.

RESULTS

A median of five cycles were administered. No objective responses were observed in the first 12 evaluable patients, and six patients showed stable disease for more than 18 weeks on therapy. Median time to progression among those with objective progression was nine weeks. One patient experienced grade 4 anemia and lymphopenia. Grade 3 adverse events included lymphopenia, neutropenia, leukopenia, diarrhea, and infection. Common grade 2 toxicities included alopecia, fatigue and anemia.

CONCLUSION

Ixabepilone administered at a dose of 40 mg/m2 every 21 days should not be advanced for further study in metastatic RCC. Given previous results, however, other dosing schedules may be worthy of further investigation.

miR-154* and miR-379 in the DLK1-DIO3 microRNA mega-cluster regulate epithelial to mesenchymal transition and bone metastasis of prostate cancer

PURPOSE

MicroRNAs in the delta-like 1 homolog-deiodinase, iodothyronine 3 (DLK1-DIO3) cluster have been shown to be critical for embryonic development and epithelial to mesenchymal transition (EMT). DLK1-DIO3 cluster miRNAs are elevated in the serum of patients with metastatic cancer. However, the biologic functions of these miRNAs in the EMT and metastasis of cancer cells are poorly understood. We previously demonstrated the oncogenic and metastatic role of miR-409-3p/5p, a member of this cluster, in prostate cancer. In this study, we defined the role of miR-154* and miR-379, two key members of this cluster, in prostate cancer progression and bone metastasis in both cell line models and clinical specimens.

EXPERIMENTAL DESIGN

Genetic manipulation of miR-154* and miR-379 was performed to determine their role in tumor growth, EMT, and bone metastasis in mouse models. We determined the expression of miR-154* in prostate cancer clinical samples and bone metastasis samples using in situ hybridization and quantum dot labeling.

RESULTS

Elevated expression of miR-154* and miR-379 was observed in bone metastatic prostate cancer cell lines and tissues, and miR-379 expression correlated with progression-free survival of patients with prostate cancer. Intracardiac inoculation (to mimic systemic dissemination) of miR-154* inhibitor-treated bone metastatic ARCaPM prostate cancer cells in mice led to decreased bone metastasis and increased survival.

CONCLUSION

miR-154* and miR-379 play important roles in prostate cancer biology by facilitating tumor growth, EMT, and bone metastasis. This finding has particular translational importance because miRNAs in the DLK1-DIO3 cluster can be attractive biomarkers and possible therapeutic targets to treat bone metastatic prostate cancer.

Abstract 3459: SRC family kinase FYN promotes MET tyrosine kinase activation, epithelial to mesenchymal transition and metastasis in human prostate cancer

Introduction: FYN is a Src family kinase (SFK) member that has been shown to be upregulated in human prostate cancer tissues and cell lines (PCa). The majority of the studies on SRC kinases have focused on the classical c-SRC. We demonstrated previously that knockdown of FYN in PCa cell lines leads to reduced tumor growth in vitro and in vivo. We hypothesized that MET, an oncogenic tyrosine kinase receptor implicated in metastasis and therapeutic resistance of a variety of solid tumors is regulated by FYN expression in prostate cancer.

Methods: We performed in vitro growth assays, migration and invasion assays and studied PCa cell response to HGF in wildtype, FYN-depleted and FYN-reconstituted cells. Additionally, we studied the role of FYN in promoting metastasis in vivo in xenograft mouse models.

Summary: In this study, we demonstrate that knockdown of FYN leads to reduced migration, invasion and metastatic dissemination of PCa cells in vitro and in vivo. Conversely, ectopic expression of FYN promotes enhanced tumor growth and invasion. Hepatocyte growth factor (HGF) induced activation of MET is perturbed in FYN knockdown cells and overexpression of FYN leads to excessive MET activation suggesting a possible feedback loop between FYN and MET in prostate cancer. Consistent these findings, PC3 prostate cancer cells overexpressing FYN are resistant to treatment with a MET inhibitor upon ligand stimulation. More importantly, we show that FYN promotes epithelial to mesenchymal transition (EMT) of PCa cells and knockdown of FYN leads to reversal of EMT and alters radiation sensitivity of PCa cells. To further identify the molecular mechanism of FYN mediated regulation of tumor growth, we performed integrated RNA sequencing analysis of FYN knockdown cells and found MET and a network of molecular targets that appear to regulate FYN mediated tumor progression and metastasis.

Conclusions: We demonstrate that FYN mediated MET activation promotes PCa invasion, EMT and metastasis. None of the SFK inhibitors currently in clinical trials are specific for SFKs alone. Therefore, it is imperative to develop and test novel inhibitors that selectively target FYN and other SFKs. Our findings have therapeutic implications since clinical trials are being performed for both SFK inhibitors and MET inhibitors in castration resistant PCa patients. Our studies reveal that FYN and MET interact in PCa cells and this interaction is clinically relevant given the success of XL-184 (a MET inhibitor) in phase III clinical trials in human prostate cancer. Clinical studies with translational endpoints are the need of the hour with agents that effectively inhibit FYN and MET in a variety of settings.

Citation Format: Murali Gururajan, Margarit Sievert, Sheldon Mink, Chia-Yi (Gina) Chu, Matteo Morello, Jake Lichterman, Michael R. Freeman, Edwin M. Posadas. SRC family kinase FYN promotes MET tyrosine kinase activation, epithelial to mesenchymal transition and metastasis in human prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3459. doi:10.1158/1538-7445.AM2014-3459

Stromal fibroblast-derived miR-409 promotes epithelial-to-mesenchymal transition and prostate tumorigenesis

Tumor-stromal interaction is a dynamic process that promotes tumor growth and metastasis via cell-cell interaction and extracellular vesicles. Recent studies demonstrate that stromal fibroblast-derived molecular signatures can be used to predict disease progression and drug resistance. To identify the epigenetic role of stromal noncoding RNAs in tumor-stromal interactions in the tumor microenvironment, we performed microRNA profiling of patient cancer-associated prostate stromal fibroblasts isolated by laser capture dissection microscopy and in bone-associated stromal models. We found specific upregulation of miR-409-3p and miR-409-5p located within the embryonically and developmentally regulated DLK1-DIO3 (delta-like 1 homolog-deiodinase, iodothyronine 3) cluster on human chromosome 14. The findings in cell lines were further validated in human prostate cancer tissues. Strikingly, ectopic expression of miR-409 in normal prostate fibroblasts conferred a cancer-associated stroma-like phenotype and led to the release of miR-409 via extracellular vesicles to promote tumor induction and epithelial-to-mesenchymal transition in vitro and in vivo. miR-409 promoted tumorigenesis through repression of tumor suppressor genes such as Ras suppressor 1 and stromal antigen 2. Thus, stromal fibroblasts derived miR-409-induced tumorigenesis, epithelial-to-mesenchymal transition and stemness of the epithelial cancer cells in vivo. Therefore, miR-409 appears to be an attractive therapeutic target to block the vicious cycle of tumor-stromal interactions that plagues prostate cancer patients.

miR-409-3p/-5p promotes tumorigenesis, epithelial-to-mesenchymal transition, and bone metastasis of human prostate cancer

PURPOSE

miR-409-3p/-5p is a miRNA expressed by embryonic stem cells, and its role in cancer biology and metastasis is unknown. Our pilot studies demonstrated elevated miR-409-3p/-5p expression in human prostate cancer bone metastatic cell lines; therefore, we defined the biologic impact of manipulation of miR-409-3p/-5p on prostate cancer progression and correlated the levels of its expression with clinical human prostate cancer bone metastatic specimens.

EXPERIMENTAL DESIGN

miRNA profiling of a prostate cancer bone metastatic epithelial-to-mesenchymal transition (EMT) cell line model was performed. A Gleason score human tissue array was probed for validation of specific miRNAs. In addition, genetic manipulation of miR-409-3p/-5p was performed to determine its role in tumor growth, EMT, and bone metastasis in mouse models.

RESULTS

Elevated expression of miR-409-3p/-5p was observed in bone metastatic prostate cancer cell lines and human prostate cancer tissues with higher Gleason scores. Elevated miR-409-3p expression levels correlated with progression-free survival of patients with prostate cancer. Orthotopic delivery of miR-409-3p/-5p in the murine prostate gland induced tumors where the tumors expressed EMT and stemness markers. Intracardiac inoculation (to mimic systemic dissemination) of miR-409-5p inhibitor-treated bone metastatic ARCaPM prostate cancer cells in mice led to decreased bone metastasis and increased survival compared with control vehicle-treated cells.

CONCLUSION

miR-409-3p/-5p plays an important role in prostate cancer biology by facilitating tumor growth, EMT, and bone metastasis. This finding bears particular translational importance as miR-409-3p/-5p appears to be an attractive biomarker and/or possibly a therapeutic target to treat bone metastatic prostate cancer.

Detection of live circulating tumor cells by a class of near-infrared heptamethine carbocyanine dyes in patients with localized and metastatic prostate cancer

Tumor cells are inherently heterogeneous and often exhibit diminished adhesion, resulting in the shedding of tumor cells into the circulation to form circulating tumor cells (CTCs). A fraction of these are live CTCs with potential of metastatic colonization whereas others are at various stages of apoptosis making them likely to be less relevant to understanding the disease. Isolation and characterization of live CTCs may augment information yielded by standard enumeration to help physicians to more accurately establish diagnosis, choose therapy, monitor response, and provide prognosis. We previously reported on a group of near-infrared (NIR) heptamethine carbocyanine dyes that are specifically and actively transported into live cancer cells. In this study, this viable tumor cell-specific behavior was utilized to detect live CTCs in prostate cancer patients. Peripheral blood mononuclear cells (PBMCs) from 40 patients with localized prostate cancer together with 5 patients with metastatic disease were stained with IR-783, the prototype heptamethine cyanine dye. Stained cells were subjected to flow cytometric analysis to identify live (NIR(+)) CTCs from the pool of total CTCs, which were identified by EpCAM staining. In patients with localized tumor, live CTC counts corresponded with total CTC numbers. Higher live CTC counts were seen in patients with larger tumors and those with more aggressive pathologic features including positive margins and/or lymph node invasion. Even higher CTC numbers (live and total) were detected in patients with metastatic disease. Live CTC counts declined when patients were receiving effective treatments, and conversely the counts tended to rise at the time of disease progression. Our study demonstrates the feasibility of applying of this staining technique to identify live CTCs, creating an opportunity for further molecular interrogation of a more biologically relevant CTC population.

Biologic activity of dasatinib administered as neoadjuvant therapy preceding radical cystectomy (RC) for muscle-invasive bladder cancer (MIBC)

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Background: Dasatinib (D) is an oral tyrosine kinase inhibitor of Src mediated signaling, and has demonstrated promising preclinical anti-tumor activity in bladder cancer with activated Src (Sonpavde G, Mol Cancer Ther, 2010). We previously reported the feasibilty of neoadjuvant D before RC for MIBC in a phase II trial (Hahn NM, ASCO, 2012). Here, we report correlative tumor tissue studies. Methods: A phase II trial (N=25) was conducted to assess the safety and biologic activity of neoadjuvant D in cT2-T4a, N0, M0 bladder cancer patients (pts) unsuitable for or willing to forego platinum-based neoadjuvant therapy. Patients received D 100 mg po once daily for 28 +/- 7 days followed by RC 8-24 hours after the last dose. Correlative studies evaluated tissues from baseline biopsy and RC for expression of phosphorylated (p) SRC family kinases (SFK) by immunohistochemistry (IHC). pSFK expression was scored on a scale from 0 - 3 by 2 pathologists. Results: The study completed accrual with enrollment of 25 patients. Both baseline and RC tumor were available and adequate for correlative studies in 14 cases. In 5 additional cases, carcinoma was available for baseline or RC tumor only. All pre- and post-treatment tissue samples demonstrated positive staining by IHC in inflammatory cells, which were used as the internal positive control. In all cases, the cancer cells were positive before treatment and the staining decreased after treatment. In 6 cases there was no detectable staining after treatment. In 9 cases (66%), pSFK levels decreased by 2 units from 2.5-3 pre-treatment to 0.5-1 post-treatment. In 5 cases, levels declined <2 units and of these, 2 demonstrated weak staining before treatment (0.5 and 1).In a separate tissue microarray from 20 RC specimens, 15 (75%) bladder cancers demonstrated pSFK expression, while all 40 control kidney and prostate cancers were negative. Conclusions: Neoadjuvant D demonstrated biologic activity in MIBC with marked decrease of pSFK in 66% of cases, while the remaining showed smaller decreases. This study also demonstrates frequent and high expression of pSFK at baseline in MIBC, suggesting that evaluation of D may be justified in a broad population.

Evaluating the safety of abiraterone acetate (AA) and docetaxel (D) administered in combination in patients (Pts) with metastatic castration-resistant prostate cancer (mCRPC)

205

Background: D and AA may have complementary mechanisms of action; coadministration may be beneficial. A phase Ib study assesses the safety of escalating doses of D + AA. Methods: Up to4 cohorts (C) of chemo-naïve mCRPC pts would receive D + AA. Data for C1 and C2 are presented. Primary end point: proportion of pts with dose-limiting toxicity (DLT) between Wks 2 and 7, defined as grade (Gr) ≥ 3 non-heme toxicity, Gr 4 neutropenia (absolute neutrophil count < 500/mm3) > 7 days (or febrile neutropenia), Gr 4 thrombocytopenia, or other intolerable toxicity. D + AA was deemed safe if ≤ 33% of pts experienced DLT. Pharmacokinetic (PK) parameters were evaluated for D and AA alone and in combination. Results: 15 pts were treated and 6 pts/C were evaluable for DLT assessment. 2 DLTs were observed in C1, and 1 in C2. 73% and 87% of pts had confirmed ≥ 90% and ≥ 50% prostate-specific antigen (PSA) decline, respectively. Median time to PSA progression has not yet been reached. Systemic exposure, based on maximum plasma concentration (Cmax) and area under the concentration–time curve [(AUC)∞ for D, AUC24 for abiraterone (ABI)], was comparable for both D and AA alone and for D + AA. 3 pts in C3 (D 75 mg/m2+ AA 1000 mg) have been treated past Wk 7 without DLT. Conclusions: D + AA was well tolerated in the cohorts tested. Preliminary results justify further evaluation of safety and efficacy in additional Cs. Clinical trial information: NCT01400555. [Table: see text]

NanoVelcro Chip for CTC enumeration in prostate cancer patients

Circulating tumor cells (CTCs) are one of the most crucial topics in rare cell biology and have become the focus of a significant and emerging area of cancer research. While CTC enumeration is a valid biomarker in prostate cancer, the current FDA-approved CTC technology is unable to detect CTCs in a large portion of late stage prostate cancer patients. Here we introduce the NanoVelcro CTC Chip, a device composed of a patterned silicon nanowire substrate (SiNW) and an overlaid polydimethylsiloxane (PDMS) chaotic mixer. Validated by two institutions participating in the study, the NanoVelcro Chip assay exhibits very consistent efficiency in CTC-capture from patient samples. The utilized protocol can be easily replicated at different facilities. We demonstrate the clinical utility of the NanoVelcro Chip by performing serial enumerations of CTCs in prostate cancer patients after undergoing systemic therapy. Changes in CTC numbers after 4-10 weeks of therapy were compared with their clinical responses. We observed a statistically significant reduction in CTCs counts in the clinical responders. We performed long-term follow up with serial CTC collection and enumeration in one patient observing variations in counts correlating with treatment response. This study demonstrates the consistency of the NanoVelcro Chip assay over time for CTC enumeration and also shows that continuous monitoring of CTC numbers can be employed to follow responses to different treatments and monitor disease progression.

High-purity prostate circulating tumor cell isolation by a polymer nanofiber-embedded microchip for whole exome sequencing

Handpick single cancer cells: a modified NanoVelcro Chip is coupled with ArcturusXT laser capture microdissection (LCM) technology to enable the detection and isolation of single circulating tumor cells (CTCs) from patients with prostate cancer (PC). This new approach paves the way for conducting next-generation sequencing (NGS) on single CTCs.

A phase II trial of neoadjuvant dasatinib (Neo-D) in muscle-invasive urothelial carcinoma of the bladder (miUCB): Hoosier Oncology Group GU07-122 trial

4586

Background: Neoadjuvant chemotherapy (NC) preceding radical cystectomy (RC) is an accepted standard for miUCB patients (pts). Dasatinib (D) is an oral tyrosine kinase inhibitor of Src mediated signaling, and has demonstrated promising preclinical anti-tumor activity, providing a rationale to evaluate Neo-D in human miUCB. Methods: A phase II trial was conducted to assess the safety and biologic activity of Neo-D in miUCB. Key eligibility criteria included: miUCB (T2-T4a, N0, M0), unsuitable or willing to forego platinum-based NC, adequate TURBT tissue available, ECOG PS 0-1, creatinine < 2 x ULN. Pts received D 100 mg po once daily for 28 +/- 7 days followed by RC 8-24 hours after the last dose. The primary endpoint was feasibility defined as > 60% of pts completing therapy without treatment-related dose limiting toxicity (DLT) specified as grade 4 hematologic toxicity, grade 3 non-hematologic toxicity, or any grade 2 toxicity > 14 days. Secondary endpoints included the assessment of biologic activity as assessed by pre- and post-treatment tumor tissue immunohistochemistry analysis of Src, pSrc, EPHA2, pEPHA2, FAK, pFAK, AKT, pAKT, CD31, Ki67, TUNEL. Results: The study completed accrual with enrollment of 25pts. 22 and 24 pts were respectively evaluable for feasibility and toxicity endpoints. Patient demographics included: median age – 62, M/F – 20/5, ECOG PS 0/1 – 19/6. Baseline tumor staging included: T2 – 17, T3 – 7. The study achieved its primary endpoint with 15 pts (68%) completing therapy without treatment related DLT’s. DLT’s included: fatigue (2 pts), DVT/PE, abdominal pain, supraventricular tachycardia, enteric fistula, and hematuria (1 pt each). Frequency of highest observed toxicity on study included: Grade 1 – 13%, Grade 2 – 38%, Grade 3 – 46%, Grade 4 – 4%. Among 22 patients, pathologic stage at RC was T1/Tis in 3 pts (14%), ≥T2 in 19 pts (86%), and node positive in 6 pts (27%). Correlative analyses of pre- and post-treatment tumor Src signaling are ongoing and will be updated at the meeting. Conclusions: Neoadjuvant dasatinib preceding RC is feasible in miUCB patients. Tumor tissue correlative studies may provide directions for further development.

A phase II study of KX2-391, an oral inhibitor of Src kinase and tubulin polymerization, in men with bone-metastatic castration-resistant prostate cancer (CRPC): A PCCTC trial

4654

Background: KX2-391 is an oral small molecule inhibitor of Src kinase and tubulin polymerization. In phase 1 trials, PSA declines were seen in men with advanced prostate cancer. Methods: A single-arm phase 2 study of KX2-391 in 31 men with chemo-naïve bone-metastatic CRPC was conducted at 5 PCCTC sites. Men received oral KX2-391 (40 mg BID) until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS) at 24 wk (progression = clinical/radiographic progression or death, but not rising PSA; PCWG2 criteria); a 50% success rate was predefined as clinically significant. Secondary endpoints were PSA progression-free survival (PPFS) at 24 wk (PSA progression = 25% PSA rise above nadir; PCWG2 criteria); median PFS; median PPFS; and max PSA decline. Exploratory outcomes included PK studies, CTC enumeration, and analysis of markers of bone resorption (urinary N-telopeptide [uNTx]; C-telopeptide [CTx]) and formation (bone alk phos [BAP]; osteocalcin). Results: The trial closed early after accrual of 31 men, due to a prespecified futility rule. In all, 26/31 men were evaluable for the primary endpoint; efficacy results are shown below. Also, 2/11 men (18%) with unfavorable (≥5) CTCs at baseline converted to favorable (<5) CTC counts on study, and 18/19 men (95%) with baseline favorable CTC counts maintained them. The proportion of men with declines in bone turnover markers was 32% (8/25) for uNTx, 21% (6/29) for CTx, 10% (3/29) for BAP, and 25% (7/28) for osteocalcin. In PK studies, median Cmax was 61 (range 16–129) ng/mL, and AUC was 156 (35–348) ng*hr/mL. Common toxicities (≥10%) included LFT elevations, leukopenia, thrombocytopenia, fatigue, nausea and constipation. Conclusions: KX2-391 dosed at 40 mg BID lacks antitumor activity in men with CRPC, but modulates bone turnover markers in some men. Because a Cmax of >142 ng/mL is required for tubulin polymerization inhibition, higher once-daily dosing will be used in future trials. [Table: see text]

Systemic therapy in renal cell carcinoma: advancing paradigms

The 21st century has seen an explosion in the development of agents for renal-cell carcinoma (RCC), a malignancy previously considered refractory to systemic therapy beyond cytokine therapy. At this time, there are six US Food and Drug Administration (FDA)-approved agents available. In addition, there was a recent favorable review by the FDA's Oncologic Drugs Advisory Committee of a next-generation vascular endothelial growth factor receptor (VEGFR) inhibitor, axitinib (Inlyta); other agents are in advanced testing. Moreover, while VEGF- and mammalian target of rapamycin (mTOR)-targeted therapies have become the mainstay of RCC treatment, other new molecular targets and therapeutic approaches are being developed. The availability of active agents also brings opportunities for additional clinical maneuvers, such as neoadjuvant and adjuvant therapy, as well as a need for decisions on combinatorial therapeutics in the advanced disease setting. Together, these developments and the issues they raise pose important challenges for oncologists and cancer biologists, given the limited number of patients and resources available for studies and the urgent clinical needs of the patients and families affected by RCC.

A randomized, phase II study of pazopanib in castrate-sensitive prostate cancer: a University of Chicago Phase II Consortium/Department of Defense Prostate Cancer Clinical Trials Consortium study

BACKGROUND

Intermittent androgen suppression (IAS) is an increasingly popular treatment option for castrate-sensitive prostate cancer. On the basis of previous data with anti-angiogenic strategies, we hypothesized that pan-inhibition of the vascular endothelial growth factor receptor using pazopanib during the IAS off period would result in prolonged time to PSA failure.

METHODS

Men with biochemically recurrent prostate cancer, whose PSA was <0.5 ng ml(-1) after 6 months of androgen deprivation therapy were randomized to pazopanib 800 mg daily or observation. The planned primary outcome was time to PSA progression >4.0 ng ml(-1).

RESULTS

Thirty-seven patients were randomized. Of 18 patients randomized to pazopanib, at the time of study closure, 4 had progressive disease, 1 remained on treatment and 13 (72%) electively disenrolled, the most common reason being patient request due to grade 1/2 toxicity (8 patients). Two additional patients were removed from treatment due to adverse events. Of 19 patients randomized to observation, at the time of study closure, 4 had progressive disease, 7 remained under protocol-defined observation and 8 (42%) had disenrolled, most commonly due to non-compliance with protocol visits (3 patients). Because of high dropout rates in both arms, the study was halted.

CONCLUSIONS

IAS is a treatment approach that may facilitate investigation of novel agents in the hormone-sensitive state. This trial attempted to investigate the role of antiangiogenic therapy in this setting, but encountered several barriers, including toxicities and patient non-compliance, which can make implementation of such a study difficult. Future investigative efforts in this arena should carefully consider drug toxicity and employ a design that maximizes patient convenience to reduce the dropout rate.

Phase 2 trial of linifanib (ABT-869) in patients with advanced renal cell cancer after sunitinib failure

PURPOSE

This study assessed the efficacy and safety of linifanib in patients with advanced renal cell carcinoma (RCC) who were previously treated with sunitinib.

MATERIALS AND METHODS

This open-label, multicentre, phase 2 trial of oral linifanib 0.25 mg/kg/day enrolled patients who had prior nephrectomy and adequate organ function. The primary end-point was objective response rate (ORR) per response evaluation criteria in solid tumors (RECIST) by central imaging. Secondary end-points were progression-free survival (PFS), overall survival (OS) and time to progression (TTP). Safety was also assessed.

RESULTS

Fifty-three patients, median age 61 years (range 40-80) were enrolled (August 2007 to October 2008) across 12 North-American centres. Median number of prior therapies was 2 (range 1-4); 43 patients (81%) had clear-cell histology. ORR was 13.2%, median PFS was 5.4 months (95% Confidence Interval (CI): 3.6, 6.0) and TTP was the same; median OS was 14.5 months (95% CI: 10.8, 24.1). The most common treatment-related adverse events (AEs) were diarrhoea (74%), fatigue (74%) and hypertension (66%), and the most common treatment-related Grade 3/4 AE was hypertension (40%).

CONCLUSIONS

Linifanib demonstrated clinically meaningful activity in patients with advanced RCC after sunitinib failure. At 0.25 mg/kg/day, significant dose modifications were required. An alternative, fixed-dosing strategy is being evaluated in other trials.