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.

Once-daily dasatinib: expansion of phase II study evaluating safety and efficacy of dasatinib in patients with metastatic castration-resistant prostate cancer

OBJECTIVES

To determine the activity and tolerability of 100-mg once-daily (QD) dasatinib in patients with metastatic castration-resistance prostate cancer (CRPC). Dasatinib, an oral Src family kinase inhibitor, has demonstrated both preclinical and clinical activity with twice-daily dosing in patients with metastatic CRPC.

METHODS

Chemotherapy-naive men with metastatic CRPC and increasing prostate-specific antigen levels were treated with dasatinib 100 mg QD. The primary measurement was a composite lack of disease progression, according to the Prostate Cancer Working Group 2 criteria, determined every 12 weeks during the study. The other analyses included changes in the prostate-specific antigen level, bone lesions, soft tissue disease, and bone turnover markers (urine N-telopeptide and bone alkaline phosphatase).

RESULTS

The present trial was designed before the publication of the recent Prostate Cancer Working Group 2 criteria; however, the analyses are presented to conform to the updated guidelines. A total of 48 patients received dasatinib. A lack of disease progression was observed in 21 patients (44%) at week 12 and in 8 (17%) at week 24. Urine N-telopeptide was reduced by ≥40% from baseline in 22 (51%) of 43 patients, and bone alkaline phosphatase was decreased in 26 (59%) of 44 patients. Dasatinib was well-tolerated, with only 6 patients (13%) with drug-related grade 3-4 adverse events and 3 (6%) with grade 3 adverse events. The most common treatment-related adverse events (≥20%) were fatigue, nausea, diarrhea, headache, and anorexia.

CONCLUSIONS

Dasatinib 100 mg QD has a favorable safety profile and maintains a similar degree of activity as the previously reported twice-daily dosing schedules. These data support additional study of dasatinib 100 mg QD for metastatic CRPC.

Once-daily dasatinib: expansion of phase II study evaluating safety and efficacy of dasatinib in patients with metastatic castration-resistant prostate cancer

OBJECTIVES

To determine the activity and tolerability of 100-mg once-daily (QD) dasatinib in patients with metastatic castration-resistance prostate cancer (CRPC). Dasatinib, an oral Src family kinase inhibitor, has demonstrated both preclinical and clinical activity with twice-daily dosing in patients with metastatic CRPC.

METHODS

Chemotherapy-naive men with metastatic CRPC and increasing prostate-specific antigen levels were treated with dasatinib 100 mg QD. The primary measurement was a composite lack of disease progression, according to the Prostate Cancer Working Group 2 criteria, determined every 12 weeks during the study. The other analyses included changes in the prostate-specific antigen level, bone lesions, soft tissue disease, and bone turnover markers (urine N-telopeptide and bone alkaline phosphatase).

RESULTS

The present trial was designed before the publication of the recent Prostate Cancer Working Group 2 criteria; however, the analyses are presented to conform to the updated guidelines. A total of 48 patients received dasatinib. A lack of disease progression was observed in 21 patients (44%) at week 12 and in 8 (17%) at week 24. Urine N-telopeptide was reduced by ≥40% from baseline in 22 (51%) of 43 patients, and bone alkaline phosphatase was decreased in 26 (59%) of 44 patients. Dasatinib was well-tolerated, with only 6 patients (13%) with drug-related grade 3-4 adverse events and 3 (6%) with grade 3 adverse events. The most common treatment-related adverse events (≥20%) were fatigue, nausea, diarrhea, headache, and anorexia.

CONCLUSIONS

Dasatinib 100 mg QD has a favorable safety profile and maintains a similar degree of activity as the previously reported twice-daily dosing schedules. These data support additional study of dasatinib 100 mg QD for metastatic CRPC.

Fyn is downstream of the HGF/MET signaling axis and affects cellular shape and tropism in PC3 cells

PURPOSE

Fyn is a member of the Src family of kinases that we have previously shown to be overexpressed in prostate cancer. This study defines the biological impact of Fyn inhibition in cancer using a PC3 prostate cancer model.

EXPERIMENTAL DESIGN

Fyn expression was suppressed in PC3 cells using an shRNA against Fyn (PC3/FYN-). Knockdown cells were characterized using standard growth curves and time-lapse video microscopy of wound assays and Dunn Chamber assays. Tissue microarray analysis was used to verify the physiologic relevance of the HGF/MET axis in human samples. Flank injections of nude mice were performed to assess in vivo growth characteristics.

RESULTS

HGF was found to be sufficient to drive Fyn-mediated events. Compared to control transductants (PC3/Ctrl), PC3/FYN- showed a 21% decrease in growth at 4 days (P = 0.05). PC3/FYN- cells were 34% longer than control cells (P = 0.018) with 50% increase in overall surface area (P < 0.001). Furthermore, when placed in a gradient of HGF, PC3/FYN- cells showed impaired directed chemotaxis down an HGF gradient in comparison to PC3/Ctrl (P = 0.001) despite a 41% increase in cellular movement speed. In vivo studies showed 66% difference of PC3/FYN- cell growth at 8 weeks using bidimensional measurements (P = 0.002).

CONCLUSIONS

Fyn plays an important role in prostate cancer biology by facilitating cellular growth and by regulating directed chemotaxis-a key component of metastasis. This finding bears particular translational importance when studying the effect of Fyn inhibition in human subjects.

Kinase inhibitors in prostate cancer

Prostate cancer is a significant public health problem around the world. Once a patient has disease that is no longer addressable by local means, the cancer is considered incurable. Therapeutic goals at this point include not only extension of survival but also alteration of the natural history which may otherwise lead to significant pain and morbidity from the disease process- all related to metastases. While effective systemic therapies do currently exist, their roles are considered limited for many patients. Given the overwhelming incidence and annual mortality figures related to prostate cancer, there continues to be an urgent need for therapeutic advances. Protein kinases have emerged as "druggable" therapeutic targets as they control a multitude of basic cellular activities, including growth, survival, proliferation, differentiation and apoptosis. Several of these kinases have oncogenic properties as in the setting of malignancy they may be overactive and/or dysregulated leading to the excessive proliferation and motility typical of cancer cells. Small molecule inhibitors have shown efficacy in several tumor models and are actively being studied in prostate cancer. This review summarizes historical and contemporary studies evaluating kinase inhibitors in the treatment of prostate cancer.

Fyn: a novel molecular target in cancer

Fyn is 59-kDa member of the Src family of kinases that is historically associated with T-cell and neuronal signaling in development and normal cellular physiology. Whereas Src has been heavily studied in cancer, less attention has been traditionally awarded to the other Src kinases such as Fyn. Our group has shown that Fyn is particularly upregulated in prostate cancer in contrast to the alternative members of the Src family. This suggests that it may mediate several important processes attributed to Src kinases in prostate cancer and other malignancies. These functions include not only cellular growth and proliferation but also morphogenesis and cellular motility. Together, these suggest a role for Fyn in both progression and metastasis. As several agents in clinical development affect Fyn activation, understanding the role that Fyn plays in cancer is of great importance in oncology. Cancer 2010. (c) 2010 American Cancer Society.

FYN is overexpressed in human prostate cancer

OBJECTIVE

To test the hypothesis that FYN, a member of the SRC family of kinases (SFKs), is up-regulated in prostate cancer, as FYN is functionally distinct from other SFKs, and interacts with FAK and paxillin (PXN), regulators of cell morphology and motility.

MATERIALS AND METHODS

Through data-mining in Oncomine (http://www.oncomine.org), cell-line profiling with immunoblotting, quantitative reverse transcription and polymerase chain reaction (RT-PCR) and immunohistochemical analysis, we described FYN expression in prostate cancer. The analysis included 32 cases of prostate cancer, nine of prostatic intraepithelial neoplasia (PIN) and 19 normal prostates. Samples were scored for the percentage of stained glands and intensity of staining (from 0 to 3). Each sample was assigned a composite score generated by multiplying percentage and intensity.

RESULTS

Data-mining showed an eight times greater FYN expression in prostate cancer than in normal tissue; this was specific to FYN and not present for other SFKs. Expression of FYN in prostate cancer cell lines (LNCaP, 22Rv1, PC3, DuPro) was detected using quantitative RT-PCR and immunoblotting. Expression of FYN and its signalling partners FAK and PXN was detected in human tissue. Comparing normal with cancer samples, there was a 2.1-fold increase in median composite score for FYN (P < 0.001) 1.7-fold increase in FAK (P < 0.001), and a doubling in PXN (P < 0.05). There was a 1.7-fold increase in FYN (P < 0.05) and a 1.6-fold increase in FAK (P < 0.01) in cancer compared with PIN.

CONCLUSIONS

These studies support the hypothesis that FYN and its related signalling partners are up-regulated in prostate cancer, and support further investigation into the role of the FYN as a therapeutic target.

Combination targeted therapy with sorafenib and bevacizumab results in enhanced toxicity and antitumor activity

PURPOSE

Sorafenib inhibits Raf kinase and vascular endothelial growth factor (VEGF) receptor. Bevacizumab is a monoclonal antibody targeted against VEGF. We hypothesized that the complementary inhibition of VEGF signaling would have synergistic therapeutic effects.

PATIENTS AND METHODS

Patients had advanced solid tumors, Eastern Cooperative Oncology Group performance status of 0 to 1, and good end-organ function. A phase I dose-escalation trial of sorafenib and bevacizumab was initiated at below-recommended single-agent doses because of possible overlapping toxicity: sorafenib 200 mg orally twice daily and bevacizumab intravenously at 5 mg/kg (dose level [DL] 1) or 10 mg/kg (DL2) every 2 weeks. Additional patients were enrolled at the maximum-tolerated dose (MTD).

RESULTS

Thirty-nine patients were treated. DL1 was the MTD and administered in cohort 2 (N = 27). Dose-limiting toxicity in DL2 was grade 3 proteinuria and thrombocytopenia. Adverse events included hypertension, hand-foot syndrome, diarrhea, transaminitis, and fatigue. Partial responses (PRs) were seen in six (43%) of 13 patients with ovarian cancer (response duration range, 4 to 22+ months) and one of three patients with renal cell cancer (response duration, 14 months). PR or disease stabilization >or= 4 months (median, 6 months; range, 4 to 22+ months) was seen in 22 (59%) of 37 assessable patients. The majority (74%) required sorafenib dose reduction to 200 mg/d at a median of four cycles (range, one to 12 cycles).

CONCLUSION

Combination therapy with sorafenib and bevacizumab has promising clinical activity, especially in patients with ovarian cancer. The rapidity and frequency of sorafenib dose reductions indicates that sorafenib at 200 mg twice daily with bevacizumab 5 mg/kg every 2 weeks may not be tolerable long term, and alternate sorafenib dosing schedules should be explored.

A prospective analysis of imatinib-induced c-KIT modulation in ovarian cancer: a phase II clinical study with proteomic profiling

BACKGROUND

c-Kit and platelet-derived growth factor receptor (PDGFR) are potential molecular targets in epithelial ovarian cancer (EOC). Imatinib inhibits the kinase domain and subsequent downstream signaling of these receptor tyrosine kinases. The objective of this study was to investigate biochemical and biologic effects of imatinib on EOC.

METHODS

Patients with recurrent EOC who had received no more than 4 prior regimens and who had good end-organ function were eligible. Imatinib was administered orally at a dose of 400 mg twice daily in continuous, 28-day cycles with reassessment imaging studies obtained every other cycle. Tumor core biopsies were obtained prior to and at 4 weeks into therapy; microdissected tumor and stroma were subjected to protein lysate array analysis. Blood samples were obtained monthly for cytokine measurements.

RESULTS

Twenty-three patients were enrolled, including 16 patients who received imatinib 600 mg daily because of gastrointestinal (GI) toxicity and fluid accumulation at the starting dose. The median time to disease progression was 2 months (range, 2-14 months). Common grade 3 toxicities included edema/ascites/pleural effusions in 11 patients (48%), GI complaints in 8 patients (35%), fatigue in 3 patients (13%), and grade 2 and 3 cytopenias in 10 patients and 3 patients (43% and 13%), respectively. Increased circulating levels of interleukin 6 were associated with grade >/=2 fluid collection (P = .02). A statistically significant trend was observed between pretreatment phosphorylated-kit levels in microdissected tumor and stroma and GI toxicity (P < .01), between tumor levels of epidermal growth factor receptor (EGFR) and PDGFR with grade of fatigue (P </= .005), and EGFR and phosphorylated-AKT levels with grade of ascites and edema (P </= .01).

CONCLUSIONS

The results of this study indicated imatinib had minimal activity as a single agent in EOC. Its ability to modulate its molecular targets suggests that it may be considered in combinatorial therapy.

A phase II and pharmacodynamic study of gefitinib in patients with refractory or recurrent epithelial ovarian cancer

BACKGROUND

The primary objective of this study was to evaluate the biochemical effects of gefitinib on its target signal-transduction pathways in patients with recurrent epithelial ovarian cancer (EOC). The secondary objectives included assessing clinical activity and toxicity and determining the association between biochemical and clinical outcomes.

METHODS

Twenty-four heavily pretreated patients with EOC who had good end-organ function and performance status and who had measurable disease received gefitinib 500 mg daily. Prospectively planned core-needle tumor biopsies were obtained before treatment and after 4 weeks. Protein expression of total and phosphorylated (p) epidermal growth factor receptor (EGFR), protein kinase B (AKT), and extracellular regulated kinase (ERK) was quantified in microdissected tumor cells using tissue lysate array proteomics.

RESULTS

All tumor samples had detectable levels of EGFR and p-EGFR. A decrease in the quantity of both EGFR and p-EGFR was observed with gefitinib therapy in >50% of patients. This was not associated with clinical benefit, nor were responses observed. However, trends for increased gastrointestinal and skin toxicity were observed with greater phosphorylation or quantities of EGFR, ERK, and AKT in tumor samples (P </= .05). Gefitinib had limited clinical activity as monotherapy despite documented target inhibition.

CONCLUSIONS

The results from this study demonstrated that gefitinib inhibited the phosphorylation of EGFR in EOC tumor cells, providing proof of target in a clinical setting. Combinatorial therapy with molecular therapeutics against complementary targets may prove successful.

A phase II study of perifosine in androgen independent prostate cancer

OBJECTIVES

Perifosine is an alkylphospholipid that has exhibited broad antineoplastic activity in preclinical studies. The primary objective of this study was to determine the clinical efficacy of this agent in the treatment of androgen-independent prostate cancer (AIPC) using PSA and clinical criteria.

PATIENTS AND METHODS

Nineteen patients with progressive, metastatic AIPC were treated with oral perifosine. Cycles were 28 days in length. A loading dose of 900 mg was given on day 1 of cycle 1 followed by a maintenance dose of 150 mg daily for the next 20 days. A loading dose of 600 mg was administered on the first day of subsequent cycles by the maintenance dose of 150 mg daily for the next 20 days. Pharmacokinetic measurements were made throughout the course of the study. Circulating epithelial cells were collected via leukapheresis on day 0, 3, and 28.

RESULTS

Median patient age was 67 years and median PSA was 180 ng/mL (range: 19-904 ng/ml). Grade 1-2 fatigue and gastrointestinal toxicities were common. Pharmacokinetic studies showed an average minimum concentration at steady-state of approximately 4059 ng/ml which correlated well with previous studies. Median time to progression was four weeks. There were no radiographic responses or PSA declines of 50% or greater related to perifosine.

CONCLUSIONS

Treatment with perifosine was complicated by fatigue and gastrointestinal toxicity. No significant clinical activity against prostate cancer was observed. This agent does not merit further study in the setting of monotherapy in this population.

Proteomic analysis for the early detection and rational treatment of cancer--realistic hope?

Proteomics is an emerging field in medical science focused on the library of proteins specific to a given biosystem, the proteome, and understanding relationships therein. This field incorporates technologies that can be applied to serum and tissue in order to extract important biological information to aid clinicians and scientists in understanding the dynamic biology of their system of interest, such as a patient with cancer. These tools include laser capture microdissection, tissue lysate arrays and mass spectrometry approaches. These new technologies are more potent coupled with advanced bioinformatics analysis. They are used to characterize the content of, and changes in, the proteome induced by physiological changes, benign and pathologic. The application of these tools has assisted in the discovery of new biomarkers and may lead to new diagnostic tests and improvements in therapeutics. These tools additionally can provide a molecular characterization of cancers, which may allow for individualized molecular therapy. Understanding the basic concepts and tools used will illustrate how best to apply these technologies for patient benefit for the early detection of cancer and improved patient care.

Proteomics and ovarian cancer: implications for diagnosis and treatment: a critical review of the recent literature

PURPOSE OF REVIEW

Epithelial ovarian cancer is the leading cause of death from gynecologic malignancies amongst American women. Emerging proteomic technologies have promise for early diagnosis and in advancing treatment directions. Application of these technologies has produced new biomarkers, diagnostic approaches, and understanding of disease biology.

RECENT FINDINGS

Mass spectral blood and tissue analysis has yielded new putative biomarkers that require further validation and assessment of diagnostic specificity and sensitivity. Protein signature patterns derived from mass spectrometry datastreams have been modeled and are moving into validation. Tissue-based protein analysis has led to identification of tumor and stromal protein and signal activation events in ovarian cancer. Clinical trials are now ascertaining tissue samples prior to and during therapy with molecularly targeted agents to evaluate modulation of targeted signaling pathways. Finally, proteomic analysis of tissues and metastases will outline biochemical events underlying the metastatic phenotype of ovarian cancer.

SUMMARY

Proteomic approaches are experimental technologies applied to ovarian and other cancers. Proper validation and use of findings may advance our understanding of biochemical events that have complicated successful detection and intervention. This knowledge is the first step in fulfilling the promise of personalized molecular medicine.

The Emerging Role of Bisphosphonates in Prostate Cancer

Bisphosphonates are a class of therapeutic agents originally designed to treat loss of bone density. It has been shown that the primary mechanism of action is inhibition of osteoclastic activity. Accumulating data show that these drugs are useful in diseases with propensities toward osseous metastases. In particular, they are effective in diseases in which there is clear upregulation of osteoclastic or osteolytic activity such as breast cancer and multiple myeloma. Despite the fact that osseous metastases in prostate cancer manifest as osteosclerosis rather than osteolysis, studies now show that bisphosphonates are useful in the management of this disease. In particular, they have demonstrated an impact on osteoporosis associated with hormonal therapy, bone pain from metastases, and skeleton-related events from prostatic adenocarcinoma. This review briefly summarizes the available clinical data on the utilization of bisphosphonates in the disease of prostate cancer.

Chaotic oscillations in cultured cells: rat prostate cancer

Normal prostate epithelial cells exhibit uniformity of structure, function, and DNA content. This uniformity is dramatically perturbed in cancer with the development of variance associated with tumor cell heterogeneity. The development of this kind of diversity is paralleled in models of chaotic oscillators that produce multiple pseudosteady states. We have tested prostatic cancer cells in culture for the presence of chaos by comparing the micromotion of two related rat prostate cancer cell lines that exhibited large differences in motility and metastatic potential. In these extremes of cancer cell types, our data suggest that the three criteria which characterize a chaotic oscillation are fulfilled by their cellular micromotions: (a) absence of defined regularity in the time series as evidenced using Fourier analysis and visual inspection; (b) determinism as evidenced by attractor reconstruction; and (c) sensitive dependence on initial conditions as evidenced by a positive Lyapunov exponent. Cellular motion was studied by using an electronic cell impedance sensor which records, in real time, the fluctuations in the resistive and capacitive properties of cells cultured on recording electrodes. Our data and a preliminary screen of other cell types support a model of established cell lines in culture as chaotic oscillators.

Synthesis and characterization of putrescine-based poly(phosphoester-urethanes)

A novel set of putrescine-based segmented polyurethanes was synthesized using 1,4-butane-diisocyanate and phosphoester diols, and was characterized for its potential as a degradable biomaterial. These poly(phosphoester-urethanes) (PPU) were flexible polymers with ultimate tensile strength (UTS) from 2 to 3 MPa, elongations up to 80% and tan delta near 0.15. The incorporation of phosphoester bonds in the backbone of the polymer by using bis(2-hydroxyethyl)phosphite (BGP) and bis(6-hydroxyhexyl)phosphite (BHP) as chain extenders resulted in hydrolytic degradation which was evaluated in vitro. By varying the content of the phosphoester diol BGP, degradation rate, as followed by mass loss and GPC, could be modulated. Polymers based on the more hydrophobic monomer, BHP, showed slower degradation than corresponding BGP based polymers. Tensile properties of PPU-B2 after 22 days in vitro degradation show more than a 50% drop in UTS and ultimate elongation, likely caused by void spaces left behind in the polymer after mass loss and swelling. The attachment of a drug, PAS, pendant to the phosphoester group of the PPU was demonstrated. PAS was linked via the spacer 4-hydroxybenzaldehyde, and free, intact drug was released in about 5 h from a thin film.