Abiraterone acetate (AA) plus prednisone (P) 5 mg QD in metastatic castration-naïve prostate cancer (mCNPC): Detailed safety analyses from the LATITUDE phase 3 trial

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Background: AA + P added to androgen deprivation therapy (ADT) improves overall survival (OS) in newly diagnosed mCNPC patients (pts). AA has been previously coadministered with P (10 mg QD). As a lower dose of P (5 mg QD) was used in LATITUDE, we conducted additional safety analyses. Methods: 1199 pts with newly diagnosed, high-risk mCNPC (≥ 2 of 3 risk factors: Gleason ≥ 8, ≥ 3 bone lesions, visceral metastases) were randomized 1:1 to AA (1 gm QD) + P (5 mg QD) + ADT or placebos (PBOs) of AA and P + ADT: median treatment duration 24 and 14 mo, respectively. Safety analyses focused on key mineralocorticoid excess (ME)-related adverse events (AEs): hypertension (HTN) and hypokalemia. Results: Increased HTN with 5 mg/d P with AA + ADT (relative risk, 1.6 [95% CI, 1.4-1.9]) was similar to prior studies using 10 mg/d P (COU-AA-301: 1.4 [0.9-2.0]; COU-AA-302: 1.6 [1.2-2.1]). Of Gr 3/4 HTN events, 87% (109/126 [AA + P + ADT]) and 83% (52/63 [PBOs + ADT]) resolved to Gr ≤ 2. There were few cerebrovascular events: AA + P + ADT, 5; PBOs + ADT, 9. The protocol allowed increasing dose of P to 10 mg for ME-related AEs, but most Gr 3/4 HTN events were managed only by supplemental antihypertensives. Prior use of antihypertensives at study entry was predictive of Gr 3/4 HTN in both treatment arms (RR: 1.85; 95% CI, 1.14-3.01). Gr 3/4 hypokalemia increased with AA + P + ADT (10.4% [62/597]) vs PBOs + ADT (1.3% [8/602]); 89% (55/62) and 100% (8/8) of these events improved to Gr ≤ 2. Less than 1% of pts in either arm discontinued therapy for ME-related AEs. Conclusions: In-depth analysis of LATITUDE data confirms the safety of 5 mg/d P with AA + ADT and helps provide practical treatment guidance for managing mCNPC. Clinical trial information: NCT01715285. [Table: see text]

Indirect treatment comparison (ITC) of abiraterone acetate (AA) plus prednisone (P) and docetaxel (DOC) on patient-reported outcomes (PROs) in metastatic castration-naïve prostate cancer (mCNPC)

200

Background: AA + P added to androgen deprivation therapy (ADT) improved overall survival among newly diagnosed mCNPC patients (pts) with high-risk disease (HRD) vs placebos (PBOs) + ADT in the phase 3 LATITUDE study. Although ADT with or without chemotherapy is recommended in clinical guidelines as the mainstay of management for mCNPC, adding DOC to ADT does not consistently improve health-related quality of life (HRQoL). We performed an ITC to understand the relative impact of AA + P vs DOC on PROs in mCNPC pts. Methods: PROs were assessed using the Functional Assessment of Cancer Therapy-Prostate (FACT-P) and Brief Pain Inventory (BPI). Mean change from baseline (BL) was based on differences in FACT-P and BPI scores between active vs control arms in LATITUDE (intention-to-treat [ITT] population) and CHAARTED (available data included mCNPC pts with high-volume disease [HVD] and low-volume disease [LVD]). Higher FACT-P score indicates better outcome/function; lower BPI score indicates better outcome/less pain. The probability of AA + P being better than DOC at 3, 6, 9, and 12 mos after treatment was based on fixed-effects Bayesian network meta-analysis. Results: Benefits in PROs with AA + P vs DOC were observed from 3 mos and sustained at least 1 year after treatment. Bayesian probability of AA + P being the better treatment for PROs ranged from 92.3% to 100%. Conclusions: Results from a Bayesian ITC suggest that AA + P was superior to DOC in improving PROs for at least 1 year after initiating treatment in men with mCNPC. In the absence of head-to-head trials, these analyses can provide useful insights on the relative impact of treatment options on HRQoL in mCNPC pts. Clinical trial information: NCT01715285. [Table: see text]

Abiraterone plus Prednisone in Metastatic, Castration-Sensitive Prostate Cancer

BACKGROUND

Abiraterone acetate, a drug that blocks endogenous androgen synthesis, plus prednisone is indicated for metastatic castration-resistant prostate cancer. We evaluated the clinical benefit of abiraterone acetate plus prednisone with androgen-deprivation therapy in patients with newly diagnosed, metastatic, castration-sensitive prostate cancer.

METHODS

In this double-blind, placebo-controlled, phase 3 trial, we randomly assigned 1199 patients to receive either androgen-deprivation therapy plus abiraterone acetate (1000 mg daily, given once daily as four 250-mg tablets) plus prednisone (5 mg daily) (the abiraterone group) or androgen-deprivation therapy plus dual placebos (the placebo group). The two primary end points were overall survival and radiographic progression-free survival.

RESULTS

After a median follow-up of 30.4 months at a planned interim analysis (after 406 patients had died), the median overall survival was significantly longer in the abiraterone group than in the placebo group (not reached vs. 34.7 months) (hazard ratio for death, 0.62; 95% confidence interval [CI], 0.51 to 0.76; P<0.001). The median length of radiographic progression-free survival was 33.0 months in the abiraterone group and 14.8 months in the placebo group (hazard ratio for disease progression or death, 0.47; 95% CI, 0.39 to 0.55; P<0.001). Significantly better outcomes in all secondary end points were observed in the abiraterone group, including the time until pain progression, next subsequent therapy for prostate cancer, initiation of chemotherapy, and prostate-specific antigen progression (P<0.001 for all comparisons), along with next symptomatic skeletal events (P=0.009). These findings led to the unanimous recommendation by the independent data and safety monitoring committee that the trial be unblinded and crossover be allowed for patients in the placebo group to receive abiraterone. Rates of grade 3 hypertension and hypokalemia were higher in the abiraterone group.

CONCLUSIONS

The addition of abiraterone acetate and prednisone to androgen-deprivation therapy significantly increased overall survival and radiographic progression-free survival in men with newly diagnosed, metastatic, castration-sensitive prostate cancer. (Funded by Janssen Research and Development; LATITUDE ClinicalTrials.gov number, NCT01715285 .).

Prognostic Index Model for Progression-Free Survival in Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer Treated With Abiraterone Acetate Plus Prednisone

BACKGROUND

Radiographic progression-free survival (rPFS) is associated with overall survival (OS) in chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC) patients. Using readily assessable baseline clinical and laboratory parameters, we developed a prognostic index model for rPFS in chemotherapy-naïve mCRPC patients without visceral disease who were treated with abiraterone acetate plus prednisone.

METHODS

Data from the abiraterone acetate plus prednisone arm of COU-AA-302 were used. rPFS was defined based on modified Prostate Cancer Working Group 2 criteria. Baseline variables were assessed for association with rPFS through univariate Cox modeling. The lower (LLN) and upper (ULN) limits of laboratory normal were used to dichotomize most laboratory parameters; baseline median was used to dichotomize prostate-specific antigen (PSA). Prognostic factors for rPFS were identified by multivariate Cox modeling. Model accuracy was estimated by the C-index.

RESULTS

Presence of lymph node metastasis (hazard ratio [HR] = 1.76, P < .0001), lactate dehydrogenase > ULN (234 IU/L) (HR = 1.71, P = .0001), ≥ 10 bone metastases (HR = 1.71, P = .0015), hemoglobin ≤ LLN (12.7 g/dL) (HR = 1.47, P = .0030) and PSA > 39.5 ng/mL (HR = 1.42, P = .0078) were associated with poor outcome. Patients were categorized into 3 prognostic groups (good, n = 230; intermediate, n = 152; poor, n = 164) based on number of risk factors. Median rPFS was calculated (27.6, 16.6, and 8.3 months for good, intermediate, and poor, respectively). The C-index was 0.83 (95% confidence interval = 0.73-0.91).

CONCLUSIONS

The prognostic index model for rPFS reveals differential outcomes based on factors readily available in clinical practice. If validated, this model can be integrated into clinical practice and design of risk-stratified trials.

LATITUDE: A phase III, double-blind, randomized trial of androgen deprivation therapy with abiraterone acetate plus prednisone or placebos in newly diagnosed high-risk metastatic hormone-naive prostate cancer

LBA3

Background: Pts with newly diagnosed mHNPC, particularly with high-risk characteristics, have a poor prognosis. ADT+docetaxel showed improved outcomes in mHNPC, but many pts are not candidates for docetaxel and may benefit from alternative therapy. AA+P is indicated for metastatic castration-resistant prostate cancer pts. LATITUDE evaluates clinical benefit of early intervention with AA+P added to ADT in newly diagnosed, high-risk mHNPC pts. Methods: 1199 pts with newly diagnosed (≤ 3 mos prior to randomization) mHNPC (ECOG PS 0-2) with ≥ 2 of 3 risk factors (Gleason ≥ 8, ≥ 3 bone lesions, measurable visceral metastases) were randomized 1:1 to ADT+AA (1 g QD) + P (5 mg QD) or ADT+PBOs of AA and P. Co-primary end points were overall survival (OS) and radiographic progression-free survival (rPFS). One rPFS (~565 events), 2 interim, and 1 final OS analyses (~426, ~554, and ~852 events) were planned. Results: At this first interim analysis (median follow-up of 30.4 mos; 406 deaths [48%]; 593 rPFS events), OS, rPFS, and all secondary end points significantly favored ADT+AA+P (Table). The IDMC unanimously recommended unblinding the study and crossing pts to ADT+AA+P. Grade 3/4 adverse events (ADT+AA+P vs ADT+PBOs) (%): hypertension (20.3 vs 10.0); hypokalemia (10.4 vs 1.3); increased ALT (5.5 vs 1.3) or AST (4.4 vs 1.5). Conclusions: Early use of AA+P added to ADT in pts with high-risk mHNPC yielded significantly improved OS, rPFS, and all secondary end points vs ADT+PBOs alone. ADT+AA+P had a favorable risk/benefit ratio and supports early intervention with AA+P in newly diagnosed, high-risk mHNPC. Clinical trial information: NCT01715285. [Table: see text]

LATITUDE: A phase III, double-blind, randomized trial of androgen deprivation therapy with abiraterone acetate plus prednisone or placebos in newly diagnosed high-risk metastatic hormone-naive prostate cancer

LBA3

The full, final text of this abstract will be available at abstracts.asco.org at 7:30 AM (EDT) on Saturday, June 3, 2017, and in the Annual Meeting Proceedings online supplement to the June 20, 2017, issue of the Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Sunday edition of ASCO Daily News.

Clinical Outcomes from Androgen Signaling-directed Therapy after Treatment with Abiraterone Acetate and Prednisone in Patients with Metastatic Castration-resistant Prostate Cancer: Post Hoc Analysis of COU-AA-302

In the COU-AA-302 trial, abiraterone acetate plus prednisone significantly increased overall survival for patients with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC). Limited information exists regarding response to subsequent androgen signaling-directed therapies following abiraterone acetate plus prednisone in patients with mCRPC. We investigated clinical outcomes associated with subsequent abiraterone acetate plus prednisone (55 patients) and enzalutamide (33 patients) in a post hoc analysis of COU-AA-302. Prostate-specific antigen (PSA) response was assessed. Median time to PSA progression was estimated using the Kaplan-Meier method. The PSA response rate (≥50% PSA decline, unconfirmed) was 44% and 67%, respectively. The median time to PSA progression was 3.9 mo (range 2.6-not estimable) for subsequent abiraterone acetate plus prednisone and 2.8 mo (range 1.8-not estimable) for subsequent enzalutamide. The majority of patients (68%) received intervening chemotherapy before subsequent abiraterone acetate plus prednisone or enzalutamide. While acknowledging the limitations of post hoc analyses and high censoring (>75%) in both treatment groups, these results suggest that subsequent therapy with abiraterone acetate plus prednisone or enzalutamide for patients who progressed on abiraterone acetate is associated with limited clinical benefit.

PATIENT SUMMARY

This analysis showed limited clinical benefit for subsequent abiraterone acetate plus prednisone or enzalutamide in patients with metastatic castration-resistant prostate cancer following initial treatment with abiraterone acetate plus prednisone. This analysis does not support prioritization of subsequent abiraterone acetate plus prednisone or enzalutamide following initial therapy with abiraterone acetate plus prednisone.

Clinical versus radiographic progression and overall survival for patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) from COU-AA-302

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Background: COU-AA-302 evaluated abiraterone acetate plus prednisone (AA) vs prednisone (P) in chemotherapy-naïve mCRPC pts, with overall survival (OS) and radiographic progression-free survival (rPFS) as co-primary end points. Per study criteria, pts with radiographic progression (RAD) only were allowed to continue treatment, while those with unequivocal clinical progression (UCP) only were not, and were censored for rPFS. We evaluated the clinical significance of survival outcomes for pts with UCP only vs RAD only from the prospective COU-AA-302 trial. Methods: UCP was defined per protocol as ≥ 1 of the following: initiation of chronic opiates, ECOG performance status (PS) decline to ≥ 3, or initiation of chemotherapy, palliative radiation therapy, or surgery. OS was evaluated for each type of progression using Cox proportional hazard models. Results: 500 (92%) pts in the AA arm and 540 (100%) in the P arm discontinued study treatment. Of the 736 pts who discontinued treatment for a protocol-defined reason, 280 (38%) discontinued for UCP only, 332 (45%) for RAD only, and 124 (17%) for both UCP and RAD. Clinical events cited as the reason for discontinuation for UCP (AA vs P arm) included pain requiring opiates (22% vs 25%), ECOG PS ≥ 3 (4% vs 5%), and initiation of chemotherapy (50% vs 53%), radiation therapy (36% vs 27%) and surgery (3% vs 5%). UCP only pts had shorter median OS compared with RAD only pts (Table). Conclusions: UCP is a criterion used as an indicator for a censored event, yet appears to confer inferior survival relative to RAD. The high frequency of UCP implies that it may be an important determinant of clinical outcome. The events that drive UCP should be defined as part of the development of more informative interim trial end points, in line with the PCWG3-proposed “no longer clinically benefitting” outcome measure, which captures pts with UCP. Clinical trial information: NCT00887198. [Table: see text]

A phase 3, double-blind, randomized placebo-controlled efficacy and safety study of abiraterone acetate in chemotherapy-naïve patients with mCRPC in China, Malaysia, Thailand and Russia

Objective

This double-blind, placebo-controlled phase 3 study was designed to compare efficacy and safety of abiraterone acetate + prednisone (abiraterone) to prednisone alone in chemotherapy-naïve, asymptomatic or mildly symptomatic metastatic castration-resistant prostate cancer (mCRPC) patients from China, Malaysia, Thailand and Russia.

Methods

Adult chemotherapy-naïve patients with confirmed prostate adenocarcinoma, Eastern Cooperative Oncology Group (ECOG) performance status (PS) grade 0–1, ongoing androgen deprivation (serum testosterone <50 ng/dL) with prostate specific antigen (PSA) or radiographic progression were randomized to receive abiraterone acetate (1000 mg, QD) + prednisone (5 mg, BID) or placebo + prednisone (5 mg, BID), until disease progression, unacceptable toxicity or consent withdrawal. Primary endpoint was improvements in time to PSA progression (TTPP).

Results

Totally, 313 patients were randomized (abiraterone: n = 157; prednisone: n = 156); and baseline characteristics were balanced. At clinical cut-off (median follow-up time: 3.9 months), 80% patients received treatment (abiraterone: n = 138, prednisone: n = 112). Median time to PSA progression was not reached with abiraterone versus 3.8 months for prednisone, attaining 58% reduction in PSA progression risk (HR = 0.418; p < 0.0001). Abiraterone-treated patients had higher confirmed PSA response rate (50% vs. 21%; relative odds = 2.4; p < 0.0001) and were 5 times more likely to achieve radiographic response than prednisone-treated patients (22.9% vs. 4.8%, p = 0.0369). Median survival was not reached. Most common (≥10% abiraterone vs. prednisone-treated) adverse events: bone pain (7% vs. 14%), pain in extremity (6% vs. 12%), arthralgia (10% vs. 8%), back pain (7% vs. 11%), and hypertension (15% vs. 14%).

Conclusion

Interim analysis confirmed favorable benefit-to-risk ratio of abiraterone in chemotherapy-naïve men with mCRPC, consistent with global study, thus supporting use of abiraterone in this patient population.

Abstract CT080: A phase II study of JNJ-42756493, a pan-FGFR tyrosine kinase inhibitor, in patients with metastatic or unresectable urothelial cancer (UC) harboring FGFR gene alterations

Background: Current treatment options for metastatic UC remain limited, and tolerability is a concern in many patients. Alterations in the fibroblast growth factor receptor (FGFR) pathway are implicated in development of non-muscle-invasive bladder cancer; FGFR3 mutations or FGFR translocations are present in ∼10-20% of patients with metastatic UC. Treatment with pan-FGFR (FGFR1-4) inhibitor JNJ-42756493 resulted in promising antitumor activity in a phase 1 trial in patients with advanced solid tumors, including 3 partial responses among 8 patients with UC (Tabernero J, et al. J Clin Oncol. 2015). Safety was manageable and as anticipated with a potent FGFR inhibitor. This phase 2 open-label study of JNJ-42756493 (NCT02365597) is being conducted to determine efficacy and safety of 2 different dose regimens in patients with metastatic or unresectable UC with specific FGFR translocations or mutations.

Methods: Eligible patients must have disease progression following chemotherapy for metastatic or surgically unresectable UC or relapse within 12 months of the last dose of neoadjuvant/adjuvant chemotherapy. There is no limit on number of prior lines of treatment. Prior immunotherapy (eg, programmed-death 1/death-ligand 1 inhibitor) is allowed. Enrollment of cisplatin-ineligible (chemotherapy naïve) pts is allowed. Patients must have measurable disease (Response Evaluation Criteria In Solid Tumors version 1.1); Eastern Cooperative Oncology Group performance status ? 2; and adequate bone marrow, liver, and kidney function (creatinine clearance ? 40 mL/min). Patients with uncontrolled cardiovascular disease or baseline phosphate persistently above the upper limit of normal are not eligible. Eligible patients are randomized to 1 of 2 oral dose regimens of JNJ-42756493 in a 28-day cycle: an intermittent (10 mg/day for 7 days followed by 7 days off drug) or a continuous (6 mg/day) regimen until a dose regimen is selected. Approximately 110 patients will be treated at the selected dose regimen. Primary end point is objective response rate; secondary end points include progression-free survival, duration of response, overall survival, safety, biomarker, and pharmacokinetic assessments. This trial is currently enrolling in 14 countries.

Citation Format: Arlene O. Siefker-Radtke, Begoña Mellado, Karel Decaestecker, John M. Burke, Anne O’ Hagan, Anjali Avadhani, Bob Zhong, Ademi Santiago-Walker, Peter De Porre, Sabine Brookman-May, Jesus Garcia-Donas. A phase II study of JNJ-42756493, a pan-FGFR tyrosine kinase inhibitor, in patients with metastatic or unresectable urothelial cancer (UC) harboring FGFR gene alterations. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT080.

Subsequent Chemotherapy and Treatment Patterns After Abiraterone Acetate in Patients with Metastatic Castration-resistant Prostate Cancer: Post Hoc Analysis of COU-AA-302

BACKGROUND

Treatment patterns for metastatic castration-resistant prostate cancer (mCRPC) have changed substantially in the last few years. In trial COU-AA-302 (chemotherapy-naïve men with mCRPC), abiraterone acetate plus prednisone (AA) significantly improved radiographic progression-free survival and overall survival (OS) when compared to placebo plus prednisone (P).

OBJECTIVE

This post hoc analysis investigated clinical responses to docetaxel as first subsequent therapy (FST) among patients who progressed following protocol-specified treatment with AA, and characterized subsequent treatment patterns among older (≥75 yr) and younger (<75 yr) patient subgroups.

DESIGN, SETTING, AND PARTICIPANTS

Data were collected at the final OS analysis (96% of expected death events). Subsequent therapy data were prospectively collected, while response and discontinuation data were collected retrospectively following discontinuation of the study drug.

INTERVENTION

At the discretion of the investigator, 67% (365/546) of patients from the AA arm received subsequent treatment with one or more agents approved for mCRPC.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Efficacy analysis was performed for patients for whom baseline and at least one post-baseline prostate-specific antigen (PSA) values were available.

RESULTS AND LIMITATIONS

Baseline and at least one post-baseline PSA values were available for 100 AA patients who received docetaxel as FST. While acknowledging the limitations of post hoc analyses, 40% (40/100) of these patients had an unconfirmed ≥50% PSA decline with first subsequent docetaxel therapy, and 27% (27/100) had a confirmed ≥50% PSA decline. The median docetaxel treatment duration among these 100 patients was 4.2 mo. Docetaxel was the most common FST among older and younger patients from each treatment arm. However, 43% (79/185) of older patients who progressed on AA received no subsequent therapy for mCRPC, compared with 17% (60/361) of younger patients.

CONCLUSIONS

Patients with mCRPC who progress with AA treatment may still derive benefit from subsequent docetaxel therapy. These data support further assessment of treatment patterns following AA treatment for mCRPC, particularly among older patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00887198.

PATIENT SUMMARY

Treatment patterns for advanced prostate cancer have changed substantially in the last few years. This additional analysis provides evidence of clinical benefit for subsequent chemotherapy in men with advanced prostate cancer whose disease progressed after treatment with abiraterone acetate. Older patients were less likely to be treated with subsequent therapy.

Biomarker Associations with Efficacy of Abiraterone Acetate and Exemestane in Postmenopausal Patients with Estrogen Receptor-Positive Metastatic Breast Cancer

PURPOSE

Abiraterone may suppress androgens that stimulate breast cancer growth. We conducted a biomarker analysis of circulating tumor cells (CTCs), formalin-fixed paraffin-embedded tissues (FFPETs), and serum samples from postmenopausal estrogen receptor (ER)⁺ breast cancer patients to identify subgroups with differential abiraterone sensitivity.

METHODS

Patients (randomized 1:1:1) were treated with 1,000 mg/d abiraterone acetate + 5 mg/d prednisone (AA), AA + 25 mg/d exemestane (AAE), or exemestane. The biomarker population included treated patients (n = 293). The CTC population included patients with ≥3 baseline CTCs (n = 104). Biomarker [e.g., androgen receptor (AR), ER, Ki-67, CYP17] expression was evaluated. Cox regression stratified by prior therapies in the metastatic setting (0/1 vs. 2) and setting of letrozole/anastrozole (adjuvant vs. metastatic) was used to assess biomarker associations with progression-free survival (PFS).

RESULTS

Serum testosterone and estrogen levels were lowered and progesterone increased with AA. Baseline AR or ER expression was not associated with PFS in CTCs or FFPETs for AAE versus exemestane, but dual positivity of AR and ER expression was associated with improved PFS [HR, 0.41; 95% confidence interval (CI), 0.16-1.07; P = 0.070]. For AR expression in FFPETs obtained <1 year prior to first dose (n = 67), a trend for improved PFS was noted for AAE versus exemestane (HR, 0.56; 95% CI, 0.24-1.33; P = 0.19).

CONCLUSIONS

An AA pharmacodynamic effect was shown by decreased serum androgen and estrogen levels and increased progesterone. AR and ER dual expression in CTCs and newly obtained FFPETs may predict AA sensitivity. Clin Cancer Res; 22(24); 6002-9. ©2016 AACR.

Low Incidence of Corticosteroid-associated Adverse Events on Long-term Exposure to Low-dose Prednisone Given with Abiraterone Acetate to Patients with Metastatic Castration-resistant Prostate Cancer

BACKGROUND

Abiraterone acetate (AA) is the prodrug of abiraterone, which inhibits CYP17A1 and testosterone synthesis and prolongs the survival of patients with metastatic castration-resistant prostate cancer (mCRPC). AA plus prednisone (P) (AA+P) is approved for the treatment of patients with mCRPC.

OBJECTIVE

To investigate whether long-term use of low-dose P with or without AA leads to corticosteroid-associated adverse events (CA-AEs) in mCRPC patients.

DESIGN, SETTING, AND PARTICIPANTS

The study included 2267 patients in COU-AA-301 and COU-AA-302. We used an inclusive Standardized MedDRA Queries-oriented approach to identify 112 preferred terms for known CA-AEs, and assessed the incidence of CA-AEs during 3-mo exposure intervals and across all P exposure levels.

INTERVENTION

All 2267 patients received 5mg of P twice daily, and 1333/2267 received AA (1g) plus P.

RESULTS AND LIMITATIONS

The CA-AE incidence after any P exposure was 25%, 26%, and 23% for any grade, and 5%, 5%, and 4% for grade ≥3 CA-AEs for all patients and the AA+P and P alone groups, respectively. The most common any-grade CA-AEs were hyperglycemia (7.4%, 7.8%, and 6.9% for all patients, AA+P, and P alone, respectively) and weight increase (4.3%, 3.9%, and 4.8%, respectively). When assessed by duration of exposure (3-mo intervals up to ≥30 mo), no discernable trend was observed for CA-AEs, including hyperglycemia and weight increase. The investigator-reported study discontinuation rate due to CA-AEs was 11/2267 (0.5%), and one patient had a CA-AE resulting in death.

CONCLUSIONS

Low-dose P given with or without AA is associated with low overall incidence of CA-AEs. The frequency of CA-AEs remained low with increased duration of exposure to P.

PATIENT SUMMARY

We assessed adverse events in patients with metastatic castration-resistant prostate cancer during long-term treatment with a low dose of a corticosteroid. We found that long-term treatment with this low-dose corticosteroid is safe and tolerable.

Abiraterone acetate for metastatic castration-resistant prostate cancer after docetaxel failure: A randomized, double-blind, placebo-controlled phase 3 bridging study

OBJECTIVES

To evaluate the efficacy and safety of abiraterone acetate-prednisone versus placebo-prednisone in Asian metastatic castration-resistant prostate cancer patients who have failed docetaxel-based chemotherapy.

METHODS

In this double-blind, phase 3 study from China, 214 patients were randomized (2:1) to abiraterone acetate 1000 mg once daily plus prednisone 5 mg twice daily and placebo plus prednisone 5 mg twice daily in 28-day treatment cycles.

RESULTS

Abiraterone acetate-prednisone treatment significantly decreased prostate-specific antigen progression risk by 49%, with longer median time to prostate-specific antigen progression of 5.55 months versus 2.76 months in the placebo-prednisone group (hazard ratio 0.506, P = 0.0001, primary end-point). There was a strong trend for improved overall survival in the abiraterone acetate-prednisone group, with a 40% decrease in the risk of death (hazard ratio 0.604, P = 0.0597); however, median survival was not reached in either group because of the short follow-up period (12.9 months) and limited number of observed death events. The prostate-specific antigen response rate was higher in the abiraterone-prednisone group (49.7%) than in the placebo-prednisone group (14.1%). A total of 37.1% patients in this group had pain progression events compared with 50.7% in the placebo-prednisone group. Abiraterone-prednisone significantly decreased the risk of pain progression by 50% (hazard ratio 0.496, P = 0.0014). The incidence of adverse events was similar between the two groups; the most common adverse events being anemia (25.9% for abiraterone-prednisone vs 22.5% for placebo-prednisone), hypokalemia (25.9% and 11.3%), bone pain (23.8% and 21.1%), hypertension (16.1% and 12.7%) and increased aspartate aminotransferase (14.7% and 15.5%), respectively.

CONCLUSIONS

Abiraterone-prednisone significantly delays disease and pain progression, and prostate-specific antigen, with a favorable benefit-risk ratio in Asian metastatic castration-resistant prostate cancer patients in the post-docetaxel setting.

Phase 1b Study of Abiraterone Acetate Plus Prednisone and Docetaxel in Patients with Metastatic Castration-resistant Prostate Cancer

Coadministration of docetaxel and abiraterone acetate plus prednisone (AA + P) may benefit patients with metastatic castration-resistant prostate cancer (mCRPC) because of complementary mechanisms of action. COU-AA-206 was a phase 1b study to determine the safe dose combination of docetaxel and AA + P in three cohorts of chemotherapy-naïve mCRPC patients. Twenty-two patients received escalating doses of docetaxel plus AA + P. The primary endpoint was the proportion of patients with a dose-limiting toxicity (DLT) between weeks 2 and 7. The recommended phase 2 dose (RP2D) was the highest safe combination of docetaxel plus AA + P. Prostate-specific antigen (PSA) changes and intensive pharmacokinetic parameters for each drug were evaluated. Docetaxel 75mg/m² + AA 1000mg + P 10mg was deemed the RP2D, with DLT in one of six patients. PSA declines from baseline of ≥50% and ≥90% were observed for 85.7% and 66.7% of patients, respectively. During median follow-up of 14.5 mo, eight patients had PSA progression and six had radiographic progression or died. Systemic exposure was comparable for docetaxel and abiraterone when given alone or in combination. Studies are ongoing to confirm the efficacy of potent androgen receptor-targeted therapy plus taxane in early mCRPC.

PATIENT SUMMARY

The combination of hormonal therapy and chemotherapy may improve outcomes in men with metastatic prostate cancer. This study demonstrates the ability to combine the hormonal therapy agent abiraterone acetate, plus prednisone, and the chemotherapy drug docetaxel with an acceptable side effect profile. A high rate of prostate-specific antigen decline was seen, but the study was small and additional research is needed before this becomes a standard approach.

Treatment patterns after abiraterone acetate in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): Post hoc analysis of COU-AA-302

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Background: Treatment patterns of mCRPC have changed substantially in the last few years. In COU-AA-302 (chemotherapy-naïve men with mCRPC), abiraterone acetate plus prednisone (AA) significantly improved radiographic progression-free survival and overall survival vs placebo plus prednisone (P). There is limited information about treatment patterns after AA. In this post hoc analysis of pts in the AA treatment arm who progressed, we characterized subsequent therapy after pts discontinued study drug. Methods: In COU-AA-302, 546 pts were randomized and received AA. Treatment patterns of pts receiving ≥ 1 subsequent therapy for mCRPC after progressing on AA were collected retrospectively and source verified. Results: As of March 2014, 8% (44/546) of pts continued on AA; 67% (365/546) received ≥ 1 subsequent therapy for mCRPC. 36% (194/546) and 15% (83/546) of pts had ≥ 2 and ≥ 3 subsequent therapies, respectively. 80% (435/543) of pts in the P arm had ≥ 1 subsequent therapy. Most frequent subsequent therapy in AA pts was taxane chemotherapy (docetaxel [DOC], cabazitaxel [CBZ]), androgen signaling–directed therapy (AA, enzalutamide [ENZ], ketoconazole [KETO]), and immunotherapy (sipuleucel-T [SIP-T]) (Table). Among AA pts who received DOC as first subsequent therapy, median age was 69 years; median duration of DOC post-AA (n = 261) was 3 months (IQR: 0.95-5.7); and PSA progression was the most common reason for discontinuation. Among AA pts with baseline PSA and ≥ 1 post-baseline PSA value, 40% (40/100) had ≥ 50% PSA decline (27/100 confirmed responses) with first subsequent DOC chemotherapy. Conclusions: This post hoc analysis indicates that treatment with subsequent therapy was common (67% and 80%) in pts with chemotherapy-naïve mCRPC who progressed with AA or P, respectively. PSA decline suggests antitumor activity in pts who progressed with AA and received subsequent DOC. Despite limitations of a retrospective analysis, these data support further assessment of subsequent therapy following AA treatment for mCRPC. Clinical trial information: NCT00887198. [Table: see text]

Prior Endocrine Therapy Impact on Abiraterone Acetate Clinical Efficacy in Metastatic Castration-resistant Prostate Cancer: Post-hoc Analysis of Randomised Phase 3 Studies

BACKGROUND

The duration of prior hormonal treatment can predict responses to subsequent therapy in patients with metastatic castration-resistant prostate cancer (mCRPC).

OBJECTIVE

To determine if prior endocrine therapy duration is an indicator of abiraterone acetate (AA) sensitivity.

DESIGN, SETTING, AND PARTICIPANTS

Post-hoc exploratory analysis of randomised phase 3 studies examining post-docetaxel (COU-AA-301) or chemotherapy-naïve mCRPC (COU-AA-302) patients receiving AA. The treatment effect on overall survival (OS), radiographic progression-free survival (rPFS), and prostate-specific antigen (PSA) response analysed by quartile duration of prior gonadotropin-releasing hormone agonists (GnRHa) or androgen receptor (AR) antagonist.

INTERVENTION

Patients were randomised to AA (1000mg, orally once daily) plus prednisone (5mg, orally twice daily) or placebo plus prednisone. Prior endocrine therapy was GnRHa (COU-AA-301, n=1127 [94%]; COU-AA-302, n=1057 [97%], 45.1 mo or 36.7 mo median duration, respectively) and/or orchiectomy (COU-AA-301, n=78 [7%] COU-AA-302, n=44 [4%]); castrated patients received prior AR antagonists (COU-AA-301, n=1015 [85%]; COU-AA-302, n=1078 [99%], 15.7 mo or 16.1 mo median duration, respectively).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cox model was used to obtain hazard ratio and associated 95% confidence interval with statistical inference by log rank statistic.

RESULTS AND LIMITATIONS

Clinical benefit with AA was observed for OS, rPFS, and PSA response for nearly all quartiles with GnRHa or AR antagonists in both COU-AA-301 and COU-AA-302. In COU-AA-301, patients with a longer duration of prior endocrine therapy tended to have greater AA OS, rPFS, and PSA response benefit, with lead-time chemotherapy bias potentially impacting COU-AA-301 results. Time to castration resistance was not captured. This analysis is limited as a post-hoc exploratory analysis.

CONCLUSIONS

In the COU-AA-301 and COU-AA-302 studies, AA produced clinical benefits regardless of prior endocrine therapy duration in patients with mCRPC.

PATIENT SUMMARY

Metastatic castration-resistant prostate cancer patients derived clinical benefits with abiraterone acetate regardless of prior endocrine therapy duration.

Converging or Crossing Curves: Untie the Gordian Knot or Cut it? Appropriate Statistics for Non-Proportional Hazards in Decitabine DACO-016 Study (AML)

Introduction

Among patients with acute myeloid leukemia (AML), the DACO-016 randomized study showed reduction in mortality for decitabine [Dacogen^® (DAC), Eisai Inc., Woodcliff Lake, NJ, USA] compared with treatment choice (TC): at primary analysis the hazard ratio (HR) was 0.85 (95% confidence interval 0.69–1.04; stratified log-rank P = 0.108). With two interim analyses, two-sided alpha was adjusted to 0.0462. With 1-year additional follow-up the HR reached 0.82 (nominal P = 0.0373). These data resulted in approval of DAC in the European Union, though not in the United States. Though pre-specified, the log-rank test could be considered not optimal to assess the observed survival difference because of the non-proportional hazard nature of the survival curves.

Methods

We applied the Wilcoxon test as a sensitivity analysis. Patients were randomized to DAC (N = 242) or TC (N = 243). One-hundred and eight (44.4%) patients in the TC arm and 91 (37.6%) patients in the DAC arm selectively crossed over to subsequent disease modifying therapies at progression, which might impact the survival beyond the median with resultant converging curves (and disproportional hazards).

Results

The stratified Wilcoxon test showed a significant improvement in median (CI 95%) overall survival with DAC [7.7 (6.2; 9.2) months] versus TC [5.0 (4.3; 6.3) months; P = 0.0458].

Conclusion

Wilcoxon test indicated significant increase in survival for DAC versus TC compared to log-rank test.

Funding

Janssen-Cilag GmbH.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-015-0238-9) contains supplementary material, which is available to authorized users.

Impact of bone-targeted therapies in chemotherapy-naïve metastatic castration-resistant prostate cancer patients treated with abiraterone acetate: post hoc analysis of study COU-AA-302

BACKGROUND

Metastatic castration-resistant prostate cancer (mCRPC) often involves bone, and bone-targeted therapy (BTT) has become part of the overall treatment strategy.

OBJECTIVE

Investigation of outcomes for concomitant BTT in a post hoc analysis of the COU-AA-302 trial, which demonstrated an overall clinical benefit of abiraterone acetate (AA) plus prednisone over placebo plus prednisone in asymptomatic or mildly symptomatic chemotherapy-naïve mCRPC patients.

DESIGN, SETTING, AND PARTICIPANTS

This report describes the third interim analysis (prespecified at 55% overall survival [OS] events) for the COU-AA-302 trial.

INTERVENTION

Patients were grouped by concomitant BTT use or no BTT use.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Radiographic progression-free survival and OS were coprimary end points. This report describes the third interim analysis (prespecified at 55% OS events) and involves patients treated with or without concomitant BTT during the COU-AA-302 study. Median follow-up for OS was 27.1 mo. Median time-to-event variables with 95% confidence intervals (CIs) were estimated using the Kaplan-Meier method. Adjusted hazard ratios (HRs), 95% CIs, and p values for concomitant BTT versus no BTT were obtained via Cox models.

RESULTS AND LIMITATIONS

While the post hoc nature of the analysis is a limitation, superiority of AA and prednisone versus prednisone alone was demonstrated for clinical outcomes with or without BTT use. Compared with no BTT use, concomitant BTT significantly improved OS (HR 0.75; p=0.01) and increased the time to ECOG deterioration (HR 0.75; p<0.001) and time to opiate use for cancer-related pain (HR 0.80; p=0.036). The safety profile of concomitant BTT with AA was similar to that reported for AA in the overall intent-to-treat population. Osteonecrosis of the jaw (all grade 1/2) with concomitant BTT use was reported in <3% of patients.

CONCLUSIONS

AA with concomitant BTT was safe and well tolerated in men with chemotherapy-naïve mCRPC. The benefits of AA on clinical outcomes were increased with concomitant BTT.

PATIENT SUMMARY

Treatment of advanced prostate cancer often includes bone-targeted therapy. This post hoc analysis showed that in patients with advanced prostate cancer who were treated with abiraterone acetate and prednisone in combination with bone-targeted therapy, there was a continued trend in prolongation of life when compared with patients treated with prednisone alone.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00887198.