Efficacy and Safety of nab-Paclitaxel vs Paclitaxel on Survival in Patients With Platinum-Refractory Metastatic Urothelial Cancer: The Canadian Cancer Trials Group BL.12 Randomized Clinical Trial.

IMPORTANCE: Treatment options for platinum-refractory metastatic urothelial cancer (mUC) are limited, and outcomes remain poor. Nab-paclitaxel is an albumin-bound formulation of paclitaxel showing promising activity and tolerability in a prior single-arm trial. OBJECTIVES: To evaluate the efficacy and safety of nab-paclitaxel vs paclitaxel in platinum-refractory mUC. DESIGN, SETTING, AND PARTICIPANTS: In this investigator-initiated, open-label, phase 2 randomized clinical trial conducted across Canada and Australia from January 2014 to April 2017, eligible patients had histologically confirmed, radiologically evident mUC of the urinary tract. Mixed histologic findings, except small cell, were permitted provided UC was the predominant histologic finding. All patients had received platinum-based chemotherapy either in the metastatic setting or were within 12 months of perioperative chemotherapy. Patients with prior taxane chemotherapy were not included. Patients had an Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0 to 2 and adequate organ function. INTERVENTIONS: Patients were randomized to nab-paclitaxel, 260 mg/m2, or paclitaxel, 175 mg/m2, every 3 weeks. MAIN OUTCOMES AND MEASURES: The primary end point was progression-free survival (PFS). RESULTS: Among 199 patients, median age was 67 (range, 24-88) years; 144 (72%) were men; 167 (84%) were ECOG PS 0-1; 59 (30%) had liver metastases; and 110 (55%) were within 6 months of prior platinum-based chemotherapy. At a median follow-up of 16.4 months, there was no significant difference between nab-paclitaxel vs paclitaxel for median PFS (3.4 months vs 3.0 months; hazard ratio [HR], 0.92; 90% CI, 0.68-1.23; 1-sided P = .31). Median overall survival was 7.5 months for nab-paclitaxel vs 8.8 months for paclitaxel (HR, 0.95; 90% CI, 0.70-1.30; 1-sided P = .40); and objective response rate (ORR) was 22% for nab-paclitaxel vs 25% for paclitaxel (P = .97). Grade 3/4 adverse events were more frequent with nab-paclitaxel (64/97 [66%]) compared with paclitaxel (45/97 [46%]), P = .009; but peripheral sensory neuropathy was similar (all grades, 72/97 [74%] vs 64/97 [66%]; grade 3/4, 7/97 [7%] vs 3/97 [3%]; P = .27). There were no apparent differences in scores for health-related quality of life. CONCLUSIONS AND RELEVANCE: In this open-label, phase 2 randomized clinical trial of patients with platinum-refractory mUC, nab-paclitaxel had similar efficacy to paclitaxel; but worse toxic effects. The ORR with either taxane, however, was higher than previously reported and similar to those reported for the immune checkpoint inhibitors, suggesting that the taxanes remain a reasonable option in this setting. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02033993.

Correlation of single arm versus randomised phase 2 oncology trial characteristics with phase 3 outcome.

BACKGROUND AND AIM: The primary aim of this study was to determine whether randomised phase 2 (RP2) trials predict phase 3 trial outcome better than single arm phase 2 (SAP2) studies. Although theoretical superiority of RP2 trials has been postulated, no empiric studies have been conducted. METHODS: Published phase 3 trials testing systemic cancer therapy were identified through a Medline search. Those of superiority design, which cited phase 2 trials supporting the experimental arm, were included. Trial design and outcome details were extracted. Statistical analysis was performed using the Generalized Estimating Equation method correlating phase 2 features with phase 3 outcome, accounting for any phase 3 duplication. RESULTS: Of 189 eligible phase 3 trials, 18.5% were in haematological malignancies and 81.5% in solid tumors. The primary outcome was positive in 79 (41.8%). These were supported by 336 phase 2 trials (range 1-9 per phase 3 trial) including 66 RP2 trials. Positive phase 2 outcome, randomised or not, correlated with positive phase 3 outcome (p=0.03). RP2 studies were not superior to SAP2 studies at predicting phase 3 study success. Phase 2 trial features not predictive of phase 3 outcome included primary endpoint, sponsorship, sample size, similarity in patient population and therapy. CONCLUSIONS: RP2 studies were not superior to SAP2 trials at predicting phase 3 study success. Further research into phase 2 trial design is required given the added resources required to conduct RP2 studies and the lack of empiric evidence supporting superiority over single arm studies.

Inhibition of phosphatidylinositol 3-kinase promotes tumor cell resistance to chemotherapeutic agents via a mechanism involving delay in cell cycle progression.

Approaches to overcome chemoresistance in cancer cells have involved targeting specific signaling pathways such as the phosphatidylinositol 3-kinase (PI3K) pathway, a stress response pathway known to be involved in the regulation of cell survival, apoptosis and growth. The present study determined the effect of PI3K inhibition on the clonogenic survival of human cancer cells following exposure to various chemotherapeutic agents. Treatment with the PI3K inhibitors LY294002 or Compound 15e resulted in increased survival of MDA-MB-231 breast carcinoma cells after exposure to doxorubicin, etoposide, 5-fluorouracil, and vincristine. Increased survival following PI3K inhibition was also observed in DU-145 prostate, HCT-116 colon and A-549 lung carcinoma cell lines exposed to doxorubicin. Increased cell survival mediated by LY294002 was correlated with a decrease in cell proliferation, which was linked to an increase in the proportion of cells in the G(1) phase of the cell cycle. Inhibition of PI3K signaling also resulted in higher levels of the cyclin-dependent kinase inhibitors p21(Waf1/Cip1) and p27(Kip1); and knockdown of p27(kip1) with siRNA attenuated resistance to doxorubicin in cells treated with LY294002. Incubation in the presence of LY294002 after exposure to doxorubicin resulted in decreased cell survival. These findings provide evidence that PI3K inhibition leads to chemoresistance in human cancer cells by causing a delay in cell cycle; however, the timing of PI3K inhibition (either before or after exposure to anti-cancer agents) may be a critical determinant of chemosensitivity.

Activated macrophages inhibit human cytotrophoblast invasiveness in vitro.

Pre-eclampsia is associated with inadequate cytotrophoblast invasion and remodeling of the uterine spiral arterioles, as well as by an aberrant maternal immune response. This study determined the effect of activated macrophages and one of its products, tumor necrosis factor (TNF)-alpha, on cytotrophoblast invasiveness. Coculture with human lipopolysaccharide-activated macrophages decreased the ability of immortalized HTR-8/ SVneo human trophoblast cells to invade through reconstituted extracellular matrix (P < 0.05). This effect of activated macrophages on trophoblast invasiveness was paralleled by abrogation of a 55-kDa caseinolytic activity corresponding to prourokinase plasminogen activator (pro-uPA) and an increased secretion of plasminogen activator inhibitor 1 (PAI1), as determined by gel zymography and ELISA, respectively. Coculture with nonactivated macrophages did not significantly affect trophoblast invasiveness or pro-uPA and PAI1 secretion. Activated macrophages secreted detectable levels of TNF, and administration of exogenous TNF significantly decreased trophoblast invasiveness (P < 0.05), increased the secretion of PAI1 (P < 0.01), and completely inhibited the pro-uPA-associated caseinolytic activity by binding to the TNF receptor 1. Moreover, addition of up to 10 ng/ml of TNF did not increase the rate of apoptosis in HTR-8/SVneo cells. Finally, the increased secretion of PAI1 by trophoblast cells cocultured with activated macrophages was significantly inhibited when a neutralizing anti-TNF antibody was added to the cocultures. These results suggest that the aberrant presence of activated macrophages around uterine vessels may contribute to inadequate trophoblast invasion and remodeling of the uterine spiral arterioles. Thus, the presence of activated macrophages may be important in the etiology of pre-eclampsia.