BACKGROUNDApalutamide, a competitive inhibitor of the androgen receptor, is under development for the treatment of prostate cancer. We evaluated the efficacy of apalutamide in men with nonmetastatic castration-resistant prostate cancer who were at high risk for the development of metastasis. METHODSWe conducted a double-blind, placebo-controlled, phase 3 trial involving men with nonmetastatic castration-resistant prostate cancer and a prostate-specific antigen doubling time of 10 months or less. Patients were randomly assigned, in a 2:1 ratio, to receive apalutamide (240 mg per day) or placebo. All the patients continued to receive androgen-deprivation therapy. The primary end point was metastasis-free survival, which was defined as the time from randomization to the first detection of distant metastasis on imaging or death. RESULTSA total of 1207 men underwent randomization (806 to the apalutamide group and 401 to the placebo group). In the planned primary analysis, which was performed after 378 events had occurred, median metastasis-free survival was 40.5 months in the apalutamide group as compared with 16.2 months in the placebo group (hazard ratio for metastasis or death, 0.28; 95% confidence interval [CI], 0.23 to 0.35; P<0.001). Time to symptomatic progression was significantly longer with apalutamide than with placebo (hazard ratio, 0.45; 95% CI, 0.32 to 0.63; P<0.001). The rate of adverse events leading to discontinuation of the trial regimen was 10.6% in the apalutamide group and 7.0% in the placebo group. The following adverse events occurred at a higher rate with apalutamide than with placebo: rash (23.8% vs. 5.5%), hypothyroidism (8.1% vs. 2.0%), and fracture (11.7% vs. 6.5%). CONCLUSIONSAmong men with nonmetastatic castration-resistant prostate cancer, metastasisfree survival and time to symptomatic progression were significantly longer with apalutamide than with placebo. (Funded by Janssen Research and Development; SPARTAN ClinicalTrials.gov number, NCT01946204.)

Purpose Antiproliferative and antiosteoclastic activity from preclinical models show potential for dasatinib, an oral SRC and SRC family kinase inhibitor, as a targeted therapy for patients with prostate cancer. This phase II study investigated the activity of dasatinib in patients with metastatic castration-resistant prostate cancer (CRPC). Experimental Design Chemotherapy-naive men with CRPC and increasing prostate-specific antigen were treated with dasatinib 100 or 70 mg twice daily. Endpoints included changes in prostate-specific antigen, bone scans, measurable disease (Response Evaluation Criteria in Solid Tumor), and markers of bone metabolism. Following Prostate Cancer Working Group 2 guidelines, lack of progression according to Response Evaluation Criteria in Solid Tumor and bone scan was determined and reported at 12 and 24 weeks. Results Forty-seven patients were enrolled and received dasatinib (initial dose 100 mg twice daily, n = 25; 70 mg twice daily, n = 22), of whom 41 (87%) had bone disease. Lack of progression was achieved in 20 (43%) patients at week 12 and in 9 (19%) patients at week 24. Of 41 evaluable patients, 21 (51%) patients achieved ≥40% reduction in urinary N-telopeptide by week 12, with 33 (80%) achieving some level of reduction anytime on study. Of 15 patients with elevated urinary N-telopeptide at baseline, 8 (53%) normalized on study. Of 40 evaluable patients, 24 (60%) had reduction in bone alkaline phosphatase at week 12 and 25 (63%) achieved some reduction on study. Dasatinib was generally well tolerated and treatment-related adverse events were moderate. Conclusions This study provides encouraging evidence of dasatinib activity in bone and reasonable tolerability in chemotherapy-naive patients with metastatic CRPC.

Summary Background Src kinase-mediated interactions between prostate cancer cells and osteoclasts might promote bone metastasis. Dasatinib inhibits tyrosine kinases, including Src kinases. Data suggests that dasatinib kinase inhibition leads to antitumour activity, affects osteoclasts, and has synergy with docetaxel, a first-line chemotherapy for metastatic castration-resistant prostate cancer. We assessed whether dasatinib plus docetaxel in chemotherapy-naive men with metastatic castration-resistant prostate cancer led to greater efficacy than with docetaxel alone. Methods In this double-blind, randomised, placebo-controlled phase 3 study, we enrolled men of 18 years or older with chemotherapy-naive, metastatic, castration-resistant prostate cancer, and adequate organ function from 186 centres across 25 countries. Eligible patients were randomly assigned (1:1) via an interactive voice response system to receive docetaxel (75 mg/m2 intravenously every 3 weeks, plus oral prednisone 5 mg twice daily), plus either dasatinib (100 mg orally once daily) or placebo until disease progression or unacceptable toxicity. Randomisation was stratified by Eastern Cooperative Oncology Group performance status (0–1 vs 2), bisphosphonate use (yes vs no), and urinary N-telopeptide (uNTx) value (<60 μmol/mol creatinine vs ≥60 μmol/mol creatinine). All patients, investigators, and personnel involved in study conduct and data analyses were blinded to treatment allocation. The primary endpoint was overall survival, analysed by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00744497. Findings Between Oct 30, 2008, and April 11, 2011, 1522 eligible patients were randomly assigned to treatment; 762 patients were assigned to dasatinib and 760 to placebo. At final analysis, median follow-up was 19.0 months (IQR 11.2–25.1) and 914 patients had died. Median overall survival was 21.5 months (95% CI 20.3–22.8) in the dasatinib group and 21.2 months (20.0–23.4) in the placebo group (stratified hazard ratio [HR] 0.99, 95.5% CI 0.87–1.13; p=0.90). The most common grade 3–4 adverse events included diarrhoea (58 [8%] patients in the dasatinib group vs 27 [4%] patients in the placebo group), fatigue (62 [8%] vs 42 [6%]), and asthenia (40 [5%] vs 23 [3%]); grade 3–4 pleural effusions were uncommon (ten [1%] vs three [<1%]). Interpretation The addition of dasatinib to docetaxel did not improve overall survival for chemotherapy-naive men with metastatic castration-resistant prostate cancer. This study does not support the combination of dasatinib and docetaxel in this population of patients. Funding Bristol-Myers Squibb.

We have developed a series of immortal human-human hybrid cell lines that express phenotypic characteristics of primary oligodendrocytes, by fusing a 6-thioguanine-resistant mutant of the human rhabdomyosarcoma RD with adult human oligodendrocytes by a lectin-enhanced polyethylene glycol procedure. Hybrids were selected in an aminopterin-containing media. In contrast to the tumor parent cells, a hybrid clone M03.13 expressed surface immunoreactivity for galactosyl cerebroside and intracellular immunoreactivity for myelin basic protein (MBP), proteolipid protein (PLP), and glial fibrillary acidic protein (GFAP). Serum deprivation or chronic treatment with a protein kinase C activator 4-beta-phorbol 12-myristate 13-acetate (PMA), but not dibutyl cyclic adenosine monophosphate induced coordinate up-regulation or de novo induction of oligodendrocyte phenotypic markers with concomitant down-regulation of GFAP expression. Consistent with immunohistochemical studies, northern blot analysis demonstrated that both MBP and PLP mRNA were up-regulated in MO3.13 cells by PMA treatment. M03.13 cells provide an immortalized clonal model system suitable for study of gene expression subserving oligodendrocyte and astrocyte phenotypes.

BACKGROUND To determine the potential efficacy of targeting both the tumor and bone microenvironment in patients with castration-resistant prostate cancer (CRPC), we conducted a phase 1/2 trial combining docetaxel with dasatinib, an oral SRC inhibitor. METHODS In phase 1, 16 men received dasatinib 50–120 mg once daily (QD) and docetaxel 60–75 mg/m2 every 21 days (Q21D). In phase 2, 30 additional men received dasatinib 100 mg QD/docetaxel 75 mg/m2 Q21D. Efficacy endpoints included changes in prostate-specific antigen (PSA), measurable disease, bone scans, and markers of bone metabolism. Safety and pharmacokinetics were also studied. RESULTS Combination dasatinib and docetaxel therapy was generally well tolerated. Thirteen of 46 patients (28%) had a grade 3/4 toxicity. Drug–drug interactions and a maximum tolerated dose were not identified. Durable 50% PSA declines occurred in 26/46 patients (57%). Of 30 patients with measurable disease, 18 (60%) had a partial response. Fourteen patients (30%) had disappearance of a lesion on bone scan. In bone-marker assessments, 33/38 (87%) and 26/34 (76%) had decreases in urinary N-telopeptide or bone-specific alkaline phosphatase levels, respectively. Twenty-eight patients (61%) received single-agent dasatinib following docetaxel discontinuation and had stabilization of disease for an additional 1–12 months. CONCLUSIONS The high objective response rate and favorable toxicity profile are promising and justify randomized studies of docetaxel and dasatinib in CRPC. Parallel declines in levels of PSA and bone markers are consistent with co-targeting of epithelial and bone compartments of the cancer. Treatment with single-agent dasatinib following docetaxel cessation warrants further study.

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.

LBA8 Background: SRC kinases may contribute to androgen independence of mCRPC.Dasatinib (DAS) inhibits tyrosine kinases including SRC kinases with preclinical evidence for antimetastatic activity, inhibition of osteoclast function in tumor microenvironment, and synergistic activity with docetaxel (D). In phase I/II trials of mCRPC patients (pts), DAS in combination with D had an acceptable safety profile with objective response rates (ORR) improved over historical data and decreased levels of bone turnover markers. Methods: READY was a multinational, randomized, double-blinded, placebo-controlled, phase III study. Pts with mCRPC (n = 1,522) were randomized (1:1) to receive either D 75 mg/m2q3wk + prednisone with double-blinded DAS 100 mg qd (DAS/D, n = 762) or placebo (PBO/D, n = 760). Primary endpoint was overall survival (OS). Secondary endpoints were ORR, time to first skeletal-related event (TFSRE), time to prostate-specific antigen progression (TPSAP), urinary N-telopeptide (uNTX) reduction, pain reduction, progression-free survival (PFS), and safety. Results: No OS difference between DAS/D and PBO/D (median, 21.5 vs. 21.2 mos; hazard ratio [HR], 0.99; log-rank P = 0.90) was observed. Results of secondary endpoints for DAS/D vs. PBO/D were: ORR (30.5 vs. 31.9%); TFSRE (median, not reached vs. 31.1 mos; HR, 0.81 [95% CI, 0.64-1.02]); uNTX reduction (66.0 vs. 60.6%); PFS (median, 11.8 vs. 11.1 mos; HR, 0.92); TPSAP (median, 8.0 vs. 7.6 mos; HR, 0.91), and pain reduction (66.6 vs. 71.5%). Twenty-three percent of DAS/D and 14% of PBO/D pts received therapy for <3 mos. Most common AEs in DAS/D arm included diarrhea, fatigue, alopecia, and nausea. Grade 3-4 AEs of interest for DAS/D vs. PBO/D included anemia (8.0 vs.5.9%), neutropenia (6.2 vs. 5.5%), hypocalcemia (3.5 vs.3.1%), GI bleeding (2.6 vs.1.3%), and pleural effusion (1.3 vs. 0.4%). Conclusions: The addition of DAS to standard-of-care chemotherapy in mCRPC pts did not improve OS. There was a modest reduction in the risk of TFSRE with DAS/D vs. PBO/D. With a median follow-up of 19 mos of 761 DAS/D-treated pts, no unexpected toxicities for DAS were observed. Clinical trial information: NCT00744497.

Dasatinib is a potent oral tyrosine kinase inhibitor which targets several kinases, including the SRC family kinases. SRC family kinases have been implicated in androgen therapy resistance that often develops in metastatic castration-resistant prostate cancer (mCRPC), which drives the need for non-androgen targeting therapies. This article describes the preclinical rationale for the use of combination dasatinib and docetaxel therapy in mCRPC, and highlights the results of a phase I–II trial in which 46 patients with mCRPC, treated with a regimen of dasatinib and docetaxel, demonstrated improvements in bone scans, high rates of soft tissue responses, and modulation of markers of bone turnover. This brief report discusses in detail follow-up data on two patients who remain alive after >2.5 years on dasatinib single-agent therapy after discontinuing docetaxel treatment.