Christopher Sweeney

Preclinical Development and Clinical Translation of a PSMA-Targeted Docetaxel Nanoparticle with a Differentiated Pharmacological Profile

A targeted nanoparticle containing docetaxel displays antitumor activity in animals and differentiated pharmacological properties in patients with advanced solid tumors. Nanomedicine: From Mice to Men There has been a lot of buzz surrounding nanomedicine. Yet, this word inspires more thoughts of futuristic medicine à la Star Trek than actual visions of the clinic. Indeed, despite the intense research focus on nano-based approaches to everything from cancer to neurodegenerative disease, few nanotechnologies have actually worked in humans. Bridging this obvious translational gap, Hrkach and colleagues have now designed the ideal nanoparticle for targeting and killing cancer cells not only in animals but also in humans. The authors first created a combinatorial library of nanoparticles of varying size, polymer composition and concentration, and processing parameters. The particles contained docetaxel (DTXL), a potent chemotherapeutic, as well as a ligand that selectively targeted prostate-specific membrane antigen, which is present on the surface of prostate cancer cells and on the neovasculature of nonprostate solid tumors. Hrkach et al. showed that the optimized targeted nanoparticle (DTXL-TNP) could release anticancer drug in a controlled manner in vitro as well as in vivo in rats, without any toxicity to the animals. In a mouse model of human prostate cancer, the DTXL-TNPs were also able to slow tumor growth to 26%, whereas the free DTXL could not stop tumors from growing 100% over the 7-week study. Hrkach and coauthors showed that the pharmacokinetic profile of DTXL-TNPs did not differ among mice, rats, and monkeys, which is an important observation when moving new drug delivery platforms from animals to humans. Indeed, their interim results from 12 cancer patients enrolled in a phase 1 clinical trial showed nanoparticle clearance over time similar to the animals. Two of these patients—one with lung metastases, one with tonsillar cancer—even showed signs of tumor shrinkage after being treated with the DTXL-TNPs. After the clinical trial is complete, we will have a better idea of whether these nanoparticles are truly effective at seeking out and killing cancer. In the meantime, we look forward to the day that “nanomedicine” is no longer a buzz word, and is instead routine clinical practice. We describe the development and clinical translation of a targeted polymeric nanoparticle (TNP) containing the chemotherapeutic docetaxel (DTXL) for the treatment of patients with solid tumors. DTXL-TNP is targeted to prostate-specific membrane antigen, a clinically validated tumor antigen expressed on prostate cancer cells and on the neovasculature of most nonprostate solid tumors. DTXL-TNP was developed from a combinatorial library of more than 100 TNP formulations varying with respect to particle size, targeting ligand density, surface hydrophilicity, drug loading, and drug release properties. Pharmacokinetic and tissue distribution studies in rats showed that the NPs had a blood circulation half-life of about 20 hours and minimal liver accumulation. In tumor-bearing mice, DTXL-TNP exhibited markedly enhanced tumor accumulation at 12 hours and prolonged tumor growth suppression compared to a solvent-based DTXL formulation (sb-DTXL). In tumor-bearing mice, rats, and nonhuman primates, DTXL-TNP displayed pharmacokinetic characteristics consistent with prolonged circulation of NPs in the vascular compartment and controlled release of DTXL, with total DTXL plasma concentrations remaining at least 100-fold higher than sb-DTXL for more than 24 hours. Finally, initial clinical data in patients with advanced solid tumors indicated that DTXL-TNP displays a pharmacological profile differentiated from sb-DTXL, including pharmacokinetics characteristics consistent with preclinical data and cases of tumor shrinkage at doses below the sb-DTXL dose typically used in the clinic.

Chemohormonal Therapy in Metastatic Hormone-Sensitive Prostate Cancer

BACKGROUND Androgen-deprivation therapy (ADT) has been the backbone of treatment for metastatic prostate cancer since the 1940s. We assessed whether concomitant treatment with ADT plus docetaxel would result in longer overall survival than that with ADT alone. METHODS We assigned men with metastatic, hormone-sensitive prostate cancer to receive either ADT plus docetaxel (at a dose of 75 mg per square meter of body-surface area every 3 weeks for six cycles) or ADT alone. The primary objective was to test the hypothesis that the median overall survival would be 33.3% longer among patients receiving docetaxel added to ADT early during therapy than among patients receiving ADT alone. RESULTS A total of 790 patients (median age, 63 years) underwent randomization. After a median follow-up of 28.9 months, the median overall survival was 13.6 months longer with ADT plus docetaxel (combination therapy) than with ADT alone (57.6 months vs. 44.0 months; hazard ratio for death in the combination group, 0.61; 95% confidence interval [CI], 0.47 to 0.80; P<0.001). The median time to biochemical, symptomatic, or radiographic progression was 20.2 months in the combination group, as compared with 11.7 months in the ADT-alone group (hazard ratio, 0.61; 95% CI, 0.51 to 0.72; P<0.001). The rate of a prostate-specific antigen level of less than 0.2 ng per milliliter at 12 months was 27.7% in the combination group versus 16.8% in the ADT-alone group (P<0.001). In the combination group, the rate of grade 3 or 4 febrile neutropenia was 6.2%, the rate of grade 3 or 4 infection with neutropenia was 2.3%, and the rate of grade 3 sensory neuropathy and of grade 3 motor neuropathy was 0.5%. CONCLUSIONS Six cycles of docetaxel at the beginning of ADT for metastatic prostate cancer resulted in significantly longer overall survival than that with ADT alone. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00309985.).

Redefining the Target: Chemotherapeutics as Antiangiogenics

Angiogenesis, or new blood vessel formation, is now known to play an important role in both growth and metastasis of many cancers. The central importance of angiogenesis and the understanding of how new blood vessels are formed, has led to novel therapies designed to interrupt this process. Though specific antiangiogenic compounds have only recently entered the clinic, they herald a new era, one in which biology is the basis for therapy. The intense interest in angiogenesis has also lead to a re-examination of the activity of many established cytotoxic agents. Claims of antiangiogenic activity abound, unfortunately, with no common criteria and often little evidence of clinical relevance. What are we to think? Have oncologists unknowingly been administering antiangiogenic therapy all these years? If chemotherapeutics are really antiangiogenics in disguise, why have they failed to cure most solid tumors? Might the hard-learned lessons of chemotherapy resistance pertain to the novel antiangiogenics as well? Though we can offer no certain answers to these important questions, we do offer a framework on which to order the rapidly burgeoning literature. We suggest criteria by which a cytotoxic agent might reasonably be considered to have meaningful antiangiogenic activity. Finally, we describe potential mechanisms of resistance to antiangiogenic chemotherapies-some of which may apply to the pure antiangiogenics currently in development.

Cabozantinib in Patients With Advanced Prostate Cancer: Results of a Phase II Randomized Discontinuation Trial

PURPOSE Cabozantinib (XL184) is an orally bioavailable tyrosine kinase inhibitor with activity against MET and vascular endothelial growth factor receptor 2. We evaluated the activity of cabozantinib in patients with castration-resistant prostate cancer (CRPC) in a phase II randomized discontinuation trial with an expansion cohort. PATIENTS AND METHODS Patients received 100 mg of cabozantinib daily. Those with stable disease per RECIST at 12 weeks were randomly assigned to cabozantinib or placebo. Primary end points were objective response rate at 12 weeks and progression-free survival (PFS) after random assignment. RESULTS One hundred seventy-one men with CRPC were enrolled. Random assignment was halted early based on the observed activity of cabozantinib. Seventy-two percent of patients had regression in soft tissue lesions, whereas 68% of evaluable patients had improvement on bone scan, including complete resolution in 12%. The objective response rate at 12 weeks was 5%, with stable disease in 75% of patients. Thirty-one patients with stable disease at week 12 were randomly assigned. Median PFS was 23.9 weeks (95% CI, 10.7 to 62.4 weeks) with cabozantinib and 5.9 weeks (95% CI, 5.4 to 6.6 weeks) with placebo (hazard ratio, 0.12; P < .001). Serum total alkaline phosphatase and plasma cross-linked C-terminal telopeptide of type I collagen were reduced by ≥ 50% in 57% of evaluable patients. On retrospective review, bone pain improved in 67% of evaluable patients, with a decrease in narcotic use in 56%. The most common grade 3 adverse events were fatigue (16%), hypertension (12%), and hand-foot syndrome (8%). CONCLUSION Cabozantinib has clinical activity in men with CRPC, including reduction of soft tissue lesions, improvement in PFS, resolution of bone scans, and reductions in bone turnover markers, pain, and narcotic use.

Phase II Randomized Study of Vaccine Treatment of Advanced Prostate Cancer (E7897): A Trial of the Eastern Cooperative Oncology Group

PURPOSE A phase II clinical trial was conducted to evaluate the feasibility and tolerability of a prime/boost vaccine strategy using vaccinia virus and fowlpox virus expressing human prostate-specific antigen (PSA) in patients with biochemical progression after local therapy for prostate cancer. The induction of PSA-specific immunity was also evaluated. PATIENTS AND METHODS A randomized clinical trial was conducted by the Eastern Cooperative Oncology group and 64 eligible patients were randomly assigned to receive four vaccinations with fowlpox-PSA (rF-PSA), three rF-PSA vaccines followed by one vaccinia-PSA (rV-PSA) vaccine, or one rV-PSA vaccine followed by three rF-PSA vaccines. The major end point was PSA response at 6 months, and immune monitoring included measurements of anti-PSA and anti-vaccinia antibody titers and PSA-specific T-cell responses. RESULTS The prime/boost schedule was well tolerated with few adverse events. Of the eligible patients, 45.3% of men remained free of PSA progression at 19.1 months and 78.1% demonstrated clinical progression-free survival. There was a trend favoring the treatment group that received a priming dose of rV-PSA. Although no significant increases in anti-PSA antibody titers were detected, 46% of patients demonstrated an increase in PSA-reactive T-cells. CONCLUSION Therapy with poxviruses expressing PSA and delivered in a prime/boost regimen was feasible and associated with minimal toxicity in the cooperative group setting. A significant proportion of men remained free of PSA and clinical progression after 19 months follow-up, and nearly half demonstrated an increase in PSA-specific T-cell responses. Phase III studies are needed to define the role of vaccination in men with prostate cancer or those who are at risk for the disease.

Active Surveillance Compared With Initial Treatment for Men With Low-Risk Prostate Cancer: A Decision Analysis

CONTEXT In the United States, 192,000 men were diagnosed as having prostate cancer in 2009, the majority with low-risk, clinically localized disease. Treatment of these cancers is associated with substantial morbidity. Active surveillance is an alternative to initial treatment, but long-term outcomes and effect on quality of life have not been well characterized. OBJECTIVE To examine the quality-of-life benefits and risks of active surveillance compared with initial treatment for men with low-risk, clinically localized prostate cancer. DESIGN AND SETTING Decision analysis using a simulation model was performed: men were treated at diagnosis with brachytherapy, intensity-modulated radiation therapy (IMRT), or radical prostatectomy or followed up by active surveillance (a strategy of close monitoring of newly diagnosed patients with serial prostate-specific antigen measurements, digital rectal examinations, and biopsies, with treatment at disease progression or patient choice). Probabilities and utilities were derived from previous studies and literature review. In the base case, the relative risk of prostate cancer-specific death for initial treatment vs active surveillance was assumed to be 0.83. Men incurred short- and long-term adverse effects of treatment. PATIENTS Hypothetical cohorts of 65-year-old men newly diagnosed as having clinically localized, low-risk prostate cancer (prostate-specific antigen level <10 ng/mL, stage ≤T2a disease, and Gleason score ≤6). MAIN OUTCOME MEASURE Quality-adjusted life expectancy (QALE). RESULTS Active surveillance was associated with the greatest QALE (11.07 quality-adjusted life-years [QALYs]), followed by brachytherapy (10.57 QALYs), IMRT (10.51 QALYs), and radical prostatectomy (10.23 QALYs). Active surveillance remained associated with the highest QALE even if the relative risk of prostate cancer-specific death for initial treatment vs active surveillance was as low as 0.6. However, the QALE gains and the optimal strategy were highly dependent on individual preferences for living under active surveillance and for having been treated. CONCLUSIONS Under a wide range of assumptions, for a 65-year-old man, active surveillance is a reasonable approach to low-risk prostate cancer based on QALE compared with initial treatment. However, individual preferences play a central role in the decision whether to treat or to pursue active surveillance.

Outcome of patients with a performance status of 2 in Eastern Cooperative Oncology Group Study E1594: A phase III trial in patients with metastatic nonsmall cell lung carcinoma

Eastern Cooperative Oncology Group (ECOG) Study E1594 compared paclitaxel and cisplatin with three newer chemotherapy doublets in the treatment of patients with advanced nonsmall cell lung carcinoma (NSCLC). The accrual of patients with an ECOG performance status (PS) of 2 was discontinued due to a perceived rate of unacceptable toxicity.

Phase II Study of Pemetrexed for Second-Line Treatment of Transitional Cell Cancer of the Urothelium

PURPOSE To assess the antitumor activity and toxicity of pemetrexed as second-line chemotherapy in patients with locally advanced or metastatic transitional cell carcinoma (TCC) of the urothelium. PATIENTS AND METHODS Eligible patients had a performance status of 0 or 1, adequate organ function, previous treatment with one prior chemotherapy regimen for locally advanced or metastatic TCC of the urothelium or relapsed within 1 year of adjuvant or neoadjuvant treatment. Patients received pemetrexed 500 mg/m2 intravenously on day 1 every 21 days, with vitamin B12, folic acid, and dexamethasone prophylaxis. RESULTS Forty-seven patients were enrolled and included in the intent-to-treat efficacy analysis. Responses: 3 (6.4%) complete responses and 10 (21.3%) partial responses produced an overall response rate of 27.7%. Ten patients (21.3%) had stable disease and 22 patients (46.8%) progressed. The median time to progressive disease was 2.9 months (95% CI, 1.7 months to 4.6 months) and median overall survival was 9.6 months (95% CI, 5.1 months to 14.6 months). Median duration of response was 5.0 months (95% CI, 3.9 months to 13.8 months). Of the 47 patients assessable for safety, grade 3 or 4 hematologic events were thrombocytopenia (8.5%; 0.0%), neutropenia (4.3%; 4.3%) and anemia (2.1%; 2.1%), respectively. Nonlaboratory toxicities included grade 4 stomatitis/pharyngitis, sepsis syndrome (one patient each), and grade 3 fatigue (three patients) and diarrhea (two patients). CONCLUSION Single-agent pemetrexed is safe and active as second-line treatment of patients with advanced TCC of the urothelium. Additional evaluation in the first- or second-line setting in TCC of the urothelium is warranted.

Management of patients with advanced prostate cancer: recommendations of the St Gallen Advanced Prostate Cancer Consensus Conference (APCCC) 2015

The first St Gallen Advanced Prostate Cancer Consensus Conference (APCCC) Expert Panel identified and reviewed available evidence for the ten most important areas of controversy in advanced prostate cancer management. Recommendations based on expert opinion are presented. Detailed decisions on treatment will involve clinical consideration of disease extent and location, prior treatments, host factors, patient preferences and logistical and economic constraints.

Nuclear Factor-κB Is Constitutively Activated in Prostate Cancer In vitro and Is Overexpressed in Prostatic Intraepithelial Neoplasia and Adenocarcinoma of the Prostate

Purpose: The transcription factor nuclear factor-κB (NF-κB) promotes the production of angiogenic, antiapoptotic, and prometastatic factors that are involved in carcinogenesis. Experimental Design: Electromobility gel shift assays were used to evaluate NF-κB DNA binding in vitro. The functional relevance of NF-κB DNA binding was assessed by both cDNA array analyses and proliferation assays of prostate cancer cells with and without exposure to an NF-κB inhibitor, parthenolide. Immunohistochemistry staining for the p65 NF-κB subunit was used to determine the frequency and location of NF-κB in 97 prostatectomy specimens. The amount of staining was quantified on a 0–3+ scale. Results: An electromobility gel shift assay confirmed the presence of NFκB DNA binding in all four prostate cancer cell lines tested. The binding was inhibited by parthenolide, and this agent also decreased multiple gene transcripts under the control of NF-κB and inhibited proliferation of prostate cancer cells. The staining results revealed overexpression of p65 in the prostatic intraepithelial neoplasia and cancer compared with the benign epithelium. Specifically, there was a predominance of 1+ and 2+ with no 3+ staining in benign epithelium, whereas there was only 2+ and 3+ staining (30 and 70%, respectively) in the cancerous areas. These differences were statistically different. There was no correlation with tumor grade or stage. Conclusions: NF-κB is constitutively activated in prostate cancer and functionally relevant in vitro. Immunohistochemistry of human prostatectomy specimens demonstrated overexpression of the active subunit of NF-κB, p65, and that this occurs at an early stage in the genesis of prostate cancer. This work supports the rationale for targeting NF-κB for the prevention and/or treatment of prostate cancer.