Niraparib with Abiraterone Acetate and Prednisone for Metastatic Castration-Resistant Prostate Cancer: Phase II QUEST Study Results

Niraparib (NIRA) is a highly selective inhibitor of poly (adenosine diphosphate-ribose) polymerase, PARP1 and PARP2, which play a role in DNA repair. The phase II QUEST study evaluated NIRA combinations in patients with metastatic castration-resistant prostate cancer who were positive for homologous recombination repair gene alterations and had progressed on 1 prior line of novel androgen receptor-targeted therapy. Results from the combination of NIRA with abiraterone acetate plus prednisone, which disrupts androgen axis signaling through inhibition of CYP17, showed promising efficacy and a manageable safety profile in this patient population.

Clinical characteristics associated with falls in patients with non-metastatic castration-resistant prostate cancer treated with apalutamide

BACKGROUND

The phase III SPARTAN study demonstrated that apalutamide significantly improves metastasis-free survival and overall survival vs. placebo in patients with non-metastatic castration-resistant prostate cancer (nmCRPC). However, patients receiving apalutamide experienced falls more frequently vs. those receiving placebo (15.6% vs. 9.0%).

METHODS

806 patients with nmCRPC randomized to apalutamide in SPARTAN and treated with apalutamide in addition to ongoing androgen deprivation therapy (ADT) were included in this post-hoc analysis investigating clinical variables associated with a subsequent fall. Time to a fall was assessed with Cox proportional-hazards models adjusted for baseline characteristics and time-varying factors. Statistical inference was based on final multivariable models.

RESULTS

Falls were reported for 125/803 (15.6%) patients treated with apalutamide and ADT. Most falls were grade 1 or 2 and did not require hospitalization. Median time from randomization to first fall was 9.2 months (range 0.1-25.3 months). In the final multivariable model of both baseline and after-baseline covariates, baseline patient characteristics (older age, poor Eastern Cooperative Oncology Group performance status, history of neuropathy, and α-blocker use before study treatment) remained significantly associated with fall; after-baseline clinical characteristics significantly associated with time to fall were development of neuropathy, arthralgia, and weight loss before fall.

CONCLUSIONS

This analysis identified risk factors for fall among nmCRPC patients treated with apalutamide. Clinical management can minimize these identified risks while enhancing patient outcomes. Preventive interventions should be considered when the identified baseline conditions and post-treatment neuropathy, arthralgia, or weight decrease are present, to reduce risk of fall.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01946204.

Association between patient-reported outcomes (PROs) and changes in prostate-specific antigen (PSA) in patients (pts) with advanced prostate cancer treated with apalutamide (APA) in the SPARTAN and TITAN studies

73

Background: In phase 3 placebo (PBO)-controlled studies, addition of APA to androgen deprivation therapy (ADT) improved overall survival, resulted in rapid and deep PSA declines, and reduced risk of disease progression while preserving health-related quality of life (HRQoL) in nonmetastatic castration-resistant prostate cancer (nmCRPC; SPARTAN) and metastatic castration-sensitive prostate cancer (mCSPC; TITAN). This post hoc analysis evaluated the association of a deep PSA decline with PROs in these studies. Methods: Pts on ADT were randomized to APA (240 mg QD) or PBO: SPARTAN 2:1 (N = 1,207; APA n = 806), TITAN 1:1 (N = 1,052; APA n = 525). Each cycle was 28 d. PROs were assessed using Functional Assessment of Cancer Therapy-Prostate (FACT-P), Brief Pain Inventory-Short Form (BPI-SF; TITAN only), and Brief Fatigue Inventory (BFI; TITAN only) at baseline, specific cycles during study treatment, and post progression up to 1 yr. A landmark analysis at Month 3 evaluated association between deep PSA decline (≤ 0.2 ng/mL) and time to subsequent deterioration in PROs (defined as decrease ≥ 10 points FACT-P total, ≥ 3 points Physical Wellbeing, ≥ 30% baseline for BPI-SF worst pain, or ≥ 2 points for BFI worst fatigue). At time of the landmark analysis, only pts continuing treatment were included; all deep PSA responses after, and all PRO deterioration events before, were ignored. Time-to-event end points were analyzed by Kaplan-Meier method and Cox proportional hazards model. Results: Median treatment durations were 32.9 mo (SPARTAN) and 39.3 mo (TITAN). Per assessment, > 90% (SPARTAN, cycles 1-81) and > 50% (TITAN, cycles 1-33) of eligible pts completed FACT-P; BPI-SF and BFI, both > 62% (TITAN, cycles 1-33). Pts in either study who achieved PSA ≤ 0.2 ng/mL at Month 3 had a lower risk of deterioration in FACT-P total or Physical Wellbeing (Table). Pts in TITAN with PSA ≤ 0.2 ng/mL at Month 3 had a lower risk of BPI-SF worst pain intensity or BFI worst fatigue intensity progression (Table). Conclusions: Deep and rapid PSA responses with APA were associated with prolonged time to deterioration in HRQoL, FACT-P Physical Wellbeing, BPI-SF worst pain intensity, and BFI worst fatigue intensity in pts with advanced PC. Clinical trial information: NCT02489318 (TITAN); NCT01946204 (SPARTAN). [Table: see text]

Exposure-response analyses of erdafitinib in patients with locally advanced or metastatic urothelial carcinoma

Background

Exposure–response analyses were conducted to explore the relationship between selected efficacy and safety endpoints and serum phosphate (PO4) concentrations, a potential biomarker of efficacy and safety, in locally advanced or metastatic urothelial carcinoma patients with FGFR alterations treated with erdafitinib.

Methods

Data from two dosing regimens of erdafitinib in a phase 2 study (NCT02365597), 6 and 8-mg/day with provision for pharmacodynamically guided titration per serum PO4 levels, were analyzed using Cox proportional hazard or logistic regression models. Efficacy endpoints were overall survival (OS), progression-free survival (PFS), and objective response rate (ORR). Safety endpoints were adverse events typical for FGFR inhibitors.

Results

Exposure-efficacy analyses on 156 patients (6-mg = 68; 8-mg = 88) showed that patients with higher serum PO4 levels within the first 6 weeks showed better OS (hazard ratio 0.57 [95% CI 0.46–0.72] per mg/dL of PO4; p = 0.01), PFS (hazard ratio 0.80 [0.67–0.94] per mg/dL of PO4; p = 0.01), and ORR (odds ratio 1.38 [1.02–1.86] per mg/dL of PO4; p = 0.04). Exposure-safety analyses on 177 patients (6-mg = 78; 8-mg = 99) showed that the incidence of selected adverse events associated with on-target off-tumor effects significantly rose with higher PO4.

Conclusions

The exploratory relationship between serum PO4 levels and efficacy/safety outcomes supported the use of pharmacodynamically guided dose titration to optimize erdafitinib’s therapeutic benefit/risk ratio.

Clinical trial registration number

NCT02365597.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00280-021-04381-4.

Erdafitinib's effect on serum phosphate justifies its pharmacodynamically guided dosing in patients with cancer

A population pharmacokinetic (PK)–pharmacodynamic (PD) model was developed using data from 345 patients with cancer. The population PK‐PD model evaluated the effect of erdafitinib total and free plasma concentrations on serum phosphate concentrations after once‐daily oral continuous (0.5–12 mg) and intermittent (10–12 mg for 7 days on/7 days off) dosing, and investigated the potential covariates affecting erdafitinib‐related changes in serum phosphate levels. Phosphate is used as a biomarker for erdafitinib's efficacy and safety: increases in serum phosphate were observed after dosing with erdafitinib, which were associated with fibroblast growth factor receptor target engagement via inhibition of renal fibroblast growth factor 23–mediated signaling. PK‐PD model‐based simulations were performed to assess the approved PD‐guided dosing algorithm of erdafitinib (8 mg once‐daily continuous dosing, with up‐titration to 9 mg based on phosphate levels [<5.5 mg/dl] and tolerability at 14–21 days of treatment). The serum phosphate concentrations increased after the first dose and reached near maximal level after 14 days of continuous treatment. Serum phosphate increased with erdafitinib free drug concentrations: doubling the free concentration resulted in a 1.8‐fold increase in drug‐related phosphate changes. Dose adjustment after at least 14 days of dosing was supported by achievement of >95% maximal serum phosphate concentration. The peak‐to‐trough fluctuation within a dosing interval was limited for serum phosphate concentrations (5.68–5.65 mg/dl on Day 14), supporting phosphate monitoring at any time relative to dosing. Baseline phosphate was higher in women, otherwise, none of the investigated covariate–parameter relationships were considered clinically relevant. Simulations suggest that the starting dose of 8‐mg with up‐titration to 9‐mg on Days 14–21 maximized the number of patients within the target serum phosphate concentrations (5.5–7 mg/dl) while limiting the number of treatment interruptions. The findings from the PK‐PD model provided a detailed understanding of the erdafitinib concentration‐related phosphate changes over time, which supports erdafitinib's dosing algorithm.

Apalutamide plus abiraterone acetate and prednisone versus placebo plus abiraterone and prednisone in metastatic, castration-resistant prostate cancer (ACIS): a randomised, placebo-controlled, double-blind, multinational, phase 3 study

BACKGROUND

The majority of patients with metastatic castration-resistant prostate cancer (mCRPC) will have disease progression of a uniformly fatal disease. mCRPC is driven by both activated androgen receptors and elevated intratumoural androgens; however, the current standard of care is therapy that targets a single androgen signalling mechanism. We aimed to investigate the combination treatment using apalutamide plus abiraterone acetate, each of which suppresses the androgen signalling axis in a different way, versus standard care in mCRPC.

METHODS

ACIS was a randomised, placebo-controlled, double-blind, phase 3 study done at 167 hospitals in 17 countries in the USA, Canada, Mexico, Europe, the Asia-Pacific region, Africa, and South America. We included chemotherapy-naive men (aged ≥18 years) with mCRPC who had not been previously treated with androgen biosynthesis signalling inhibitors and were receiving ongoing androgen deprivation therapy, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and a Brief Pain Inventory-Short Form question 3 (ie, worst pain in the past 24 h) score of 3 or lower. Patients were randomly assigned (1:1) via a centralised interactive web response system with a permuted block randomisation scheme (block size 4) to oral apalutamide 240 mg once daily plus oral abiraterone acetate 1000 mg once daily and oral prednisone 5 mg twice daily (apalutamide plus abiraterone-prednisone group) or placebo plus abiraterone acetate and prednisone (abiraterone-prednisone group), in 28-day treatment cycles. Randomisation was stratified by presence or absence of visceral metastases, ECOG performance status, and geographical region. Patients, the investigators, study team, and the sponsor were masked to group assignments. An independent data-monitoring committee continually monitored data to ensure ongoing patient safety, and reviewed efficacy data. The primary endpoint was radiographic progression-free survival assessed in the intention-to-treat population. Safety was reported for all patients who received at least one dose of study drug. This study is completed and no longer recruiting and is registered with ClinicalTrials.gov, number NCT02257736.

FINDINGS

982 men were enrolled and randomly assigned from Dec 10, 2014 to Aug 30, 2016 (492 to apalutamide plus abiraterone-prednisone; 490 to abiraterone-prednisone). At the primary analysis (median follow-up 25·7 months [IQR 23·0-28·9]), median radiographic progression-free survival was 22·6 months (95% CI 19·4-27·4) in the apalutamide plus abiraterone-prednisone group versus 16·6 months (13·9-19·3) in the abiraterone-prednisone group (hazard ratio [HR] 0·69, 95% CI 0·58-0·83; p<0·0001). At the updated analysis (final analysis for overall survival; median follow-up 54·8 months [IQR 51·5-58·4]), median radiographic progression-free survival was 24·0 months (95% CI 19·7-27·5) versus 16·6 months (13·9-19·3; HR 0·70, 95% CI 0·60-0·83; p<0·0001). The most common grade 3-4 treatment-emergent adverse event was hypertension (82 [17%] of 490 patients receiving apalutamide plus abiraterone-prednisone and 49 [10%] of 489 receiving abiraterone-prednisone). Serious treatment-emergent adverse events occurred in 195 (40%) patients receiving apalutamide plus abiraterone-prednisone and 181 (37%) patients receiving abiraterone-prednisone. Drug-related treatment-emergent adverse events with fatal outcomes occurred in three (1%) patients in the apalutamide plus abiraterone-prednisone group (2 pulmonary embolism, 1 cardiac failure) and five (1%) patients in the abiraterone-prednisone group (1 cardiac failure and 1 cardiac arrest, 1 mesenteric arterial occlusion, 1 seizure, and 1 sudden death).

INTERPRETATION

Despite the use of an active and established therapy as the comparator, apalutamide plus abiraterone-prednisone improved radiographic progression-free survival. Additional studies to identify subgroups of patients who might benefit the most from combination therapy are needed to further refine the treatment of mCRPC.

FUNDING

Janssen Research & Development.

Analysis of two poor prognosis subgroups in ACIS evaluating apalutamide + abiraterone acetate plus prednisone (APA + AAP) versus placebo (PBO) + AAP in metastatic castration-resistant prostate cancer (mCRPC)

5037

Background: In the double-blind PBO-controlled ACIS study, investigator-assessed radiographic progression-free survival (rPFS) was significantly improved with APA + AAP vs PBO + AAP in chemo-naive mCRPC, with no significant new safety signals (Rathkopf ASCO GU 2021). Among prespecified subgroups, efficacy and safety were explored in two difficult to treat subgroups: pts with visceral disease (VD; liver, lung, and/or adrenal gland metastasis) or age ≥ 75 y. Methods: Pts with mCRPC with ongoing ADT and no prior life-prolonging treatment were randomized 1:1 to APA (240 mg QD) + AA (1000 mg QD) + P (5 mg BID) or PBO + AAP. Stratified: presence or absence of VD, ECOG PS 0 or 1, geographic region. Primary end point: rPFS (randomization to radiographic progression or death); secondary end points: overall survival (OS), time to initiation of cytotoxic chemotherapy, time to chronic opioid use, time to pain progression, safety. Results: 982 pts enrolled. 14.6% had VD and 35.9% were ≥ 75 y. Median rPFS, OS, and time to pain progression favored APA + AAP vs AAP (HR < 1) in both subgroups (Table). For pts ≥ 75 y, rPFS and OS were ≥ 7 mo longer with APA + AAP. Overall, treatment-emergent adverse events (TEAEs) were similar (all > 94%) in pts with VD, ≥ 75 y, and overall safety population; hypertension was more frequent with APA + AAP vs AAP mainly in pts ≥ 75 y (31.7% vs 17.6%). Grade 3/4 TEAEs (APA + AAP vs AAP): VD, 60.8%, n = 74 vs 48.5%, n = 68; ≥ 75 y, 71.5%, n = 186 vs 68.5%, n = 165; overall, 63.3%, n = 490 vs 56.2%, n = 489. TEAEs leading to discontinuation: VD, 17.6% vs 5.9%; ≥ 75 y, 26.3% vs 20.6%; overall, 16.9% vs 12.5%. TEAEs leading to death: VD, 6.8% vs 5.9%; ≥ 75 y, 5.4% vs 13.9%; overall, 3.5% vs 7.6%. Conclusions: In this analysis of two difficult to treat subgroups, addition of APA to AAP favored rPFS and OS. Safety, while generally consistent with the overall population, showed higher hypertension rate in ≥ 75 y and TEAEs leading to discontinuation in VD. Clinical trial information: NCT02257736. [Table: see text]

Modernizing Clinical Trial Eligibility Criteria: Recommendations of the ASCO-Friends of Cancer Research Prior Therapies Work Group

PURPOSE

Restrictive eligibility criteria induce differences between clinical trial and "real-world" treatment populations. Restrictions based on prior therapies are common; minimizing them when appropriate may increase patient participation in clinical trials.

EXPERIMENTAL DESIGN

A multi-stakeholder working group developed a conceptual framework to guide evaluation of prevailing practices with respect to using prior treatment as selection criteria for clinical trials. The working group made recommendations to minimize restrictions based on prior therapies within the boundaries of scientific validity, patient centeredness, distributive justice, and beneficence.

RECOMMENDATIONS

(i) Patients are eligible for clinical trials regardless of the number or type of prior therapies and without requiring a specific therapy prior to enrollment unless a scientific or clinically based rationale is provided as justification. (ii) Prior therapy (either limits on number and type of prior therapies or requirements for specific therapies before enrollment) could be used to determine eligibility in the following cases: a) the agents being studied target a specific mechanism or pathway that could potentially interact with a prior therapy; b) the study design requires that all patients begin protocol-specified treatment at the same point in the disease trajectory; and c) in randomized clinical studies, if the therapy in the control arm is not appropriate for the patient due to previous therapies received. (iii) Trial designers should consider conducting evaluation separately from the primary endpoint analysis for participants who have received prior therapies.

CONCLUSIONS

Clinical trial sponsors and regulators should thoughtfully reexamine the use of prior therapy exposure as selection criteria to maximize clinical trial participation.See related commentary by Giantonio, p. 2369.

Final results from ACIS, a randomized, placebo (PBO)-controlled double-blind phase 3 study of apalutamide (APA) and abiraterone acetate plus prednisone (AAP) versus AAP in patients (pts) with chemo-naive metastatic castration-resistant prostate cancer (mCRPC)

9

Background: As mCRPC is driven by activated androgen receptors and elevated intratumoral androgens, androgen annihilation may require dual inhibition. APA and AA are approved prostate cancer therapies that have distinct receptor inhibition and ligand suppression actions, respectively. ACIS compared radiographic progression-free survival (rPFS) of APA + AAP vs PBO + AAP in chemo-naive mCRPC. Methods: mCRPC pts with ongoing androgen deprivation therapy (ADT) but no other life-prolonging treatment since diagnosis were randomized 1:1 to APA (240 mg po QD) + AA (1000 mg po QD) + P (5 mg po BID) or PBO + AAP (stratified by presence or absence of visceral metastases, Eastern Cooperative Oncology Group performance status 0 or 1, and geographic region). The primary end point was rPFS (investigator assessed; defined from randomization date to radiographic progression date or death). Secondary/other end points included prostate-specific antigen (PSA) response, overall survival (OS), safety, time to PSA progression, chronic opioid use, initiation of cytotoxic chemotherapy, and pain progression. Results: 982 pts were enrolled (Dec 2014 to Aug 2016). Median rPFS was extended 6 mos with APA + AAP (22.6 mos) vs AAP (16.6 mos) (HR 0.69 [95% CI 0.58-0.83]; p < 0.0001) at the final analysis for rPFS, coinciding with the first interim analysis of OS (median follow-up time 25.7 mo). At final analysis, treatment with APA + AAP vs AAP showed a significantly higher rate of confirmed ≥ 50% PSA decline. Although not statistically significant, treatment with APA + AAP vs AAP showed a longer median OS. Time to PSA progression, chronic opioid use, initiation of cytotoxic chemotherapy, and pain progression did not differ statistically significantly between arms. The safety profile was consistent with prior drug experience, with no new safety concerns. Grade 3/4 treatment-emergent adverse events (TEAEs) were reported in 63.3% (310/490) of APA + AAP–treated pts vs 56.2% (275/489) of AAP-treated pts, with more grade 3 (56.1%, 275/490 vs 45.6%, 223/489) and less grade 4 (7.1%, 35/490 vs 10.6%, 52/489) TEAEs, respectively. Results based on biomarker subpopulations and quality of life will be presented. Conclusions: The ACIS final analysis met the primary end point and demonstrated a 31% reduction in risk of radiographic progression or death in chemo-naive mCRPC pts treated with the combination of APA + AAP with ADT vs AAP with ADT. Funding: Janssen Research & Development. Trial registration: NCT02257736. Clinical trial information: NCT02257736. [Table: see text]

Impact of clinical versus radiographic progression on clinical outcomes in metastatic castration-resistant prostate cancer

OBJECTIVES

Unequivocal clinical progression (UCP)-a worsening of clinical status with or without radiographic progression (RAD)-represents a distinct mode of disease progression in metastatic prostate cancer. We evaluated the prevalence, risk factors and the impact of UCP on survival outcomes.

METHODS

A post-hoc analysis of the COU-AA-302, a randomised phase 3 study of abiraterone plus prednisone (AAP) versus prednisone was performed. Baseline characteristics were summarised. Cox proportional-hazards model and Kaplan-Meier method were used for survival and time to event analyses, respectively. Iterative multiple imputation method was used for correlation between clinicoradiographic progression-free survival (crPFS) and overall survival (OS).

RESULTS

Of 736 patients with disease progression, 280 (38%) had UCP-only and 124 (17%) had UCP plus RAD. Prognostic index model high-risk group was associated with increased likelihood of UCP (p<0.0001). Median OS was 25.7 months in UCP-only and 33.0 months for RAD-only (HR 1.39; 95% CI 1.16 to 1.66; p=0.0003). UCP adversely impacted OS in both treatment groups. Lowest OS was seen in patients with prostate specific antigen (PSA)-non-response plus UCP-only progression (median OS 22.6 months (95% CI 20.7 to 24.4)). Including UCP events lowered estimates of treatment benefit-median crPFS was 13.3 months (95% CI 11.1 to 13.8) versus median rPFS of 16.5 months (95% CI 13.8 to 16.8) in AAP group. Finally, crPFS showed high correlation with OS (r=0.67; 95% CI 0.63 to 0.71).

CONCLUSIONS

UCP is a common and clinically relevant phenomenon in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with AAP or prednisone. UCP is prognostic and associated with inferior OS and post-progression survival. A combination of PSA-non-response and UCP identifies patients with poorest survival. When included in PFS analysis, UCP diminishes estimates of treatment benefit. Continued study of UCP in mCRPC is warranted.

Apalutamide and Overall Survival in Prostate Cancer

BACKGROUND

The phase 3 SPARTAN study evaluated apalutamide versus placebo in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) and prostate-specific antigen doubling time of ≤10 mo. At primary analysis, apalutamide improved median metastasis-free survival (MFS) by 2 yr and overall survival (OS) data were immature.

OBJECTIVE

We report the prespecified event-driven final analysis for OS.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1207 patients with nmCRPC (diagnosed by conventional imaging) were randomised 2:1 to apalutamide (240mg/d) or placebo, plus on-going androgen deprivation therapy. After MFS was met and the study was unblinded, 76 (19%) patients still receiving placebo crossed over to apalutamide.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

OS and time to cytotoxic chemotherapy (TTChemo) were analysed by group-sequential testing with O'Brien-Fleming-type alpha spending function.

RESULTS AND LIMITATIONS

At median 52-mo follow-up, 428 deaths had occurred. The median treatment duration was 32.9 mo for apalutamide group and 11.5 mo for placebo group. Median OS was markedly longer with apalutamide versus placebo, reaching prespecified statistical significance (73.9 vs 59.9 mo, hazard ratio [HR]: 0.78 [95% confidence interval {CI}, 0.64-0.96]; p=0.016). Apalutamide also lengthened TTChemo versus placebo (HR: 0.63 [95% CI, 0.49-0.81]; p=0.0002). Discontinuation rates in apalutamide and placebo groups due to progressive disease were 43% and 74%, and due to adverse events 15% and 8.4%, respectively. Subsequent life-prolonging therapy was received by 371 (46%) patients in the apalutamide arm and by 338 (84%) patients in the placebo arm including 59 patients who received apalutamide after crossover. Safety was consistent with previous reports; when adverse events were adjusted for treatment exposure, rash had the greatest difference of incidence between the apalutamide and placebo groups.

CONCLUSIONS

Extension of OS with apalutamide compared with placebo conferred impactful benefit in patients with nmCRPC. There was a 22% reduction in the hazard of death in the apalutamide group despite 19% crossover (placebo to apalutamide) and higher rates of subsequent therapy in the placebo group.

PATIENT SUMMARY

With data presented herein, all primary and secondary study end points of SPARTAN were met; findings demonstrate the value of apalutamide as a treatment option for nonmetastatic castration-resistant prostate cancer.

Final survival results from SPARTAN, a phase III study of apalutamide (APA) versus placebo (PBO) in patients (pts) with nonmetastatic castration-resistant prostate cancer (nmCRPC)

5516

Background: SPARTAN evaluated APA vs PBO in pts with nmCRPC and a prostate-specific antigen doubling time of ≤ 10 mo receiving androgen deprivation therapy (ADT). At primary end point analysis of metastasis-free survival (MFS), APA significantly improved median MFS by 2 yrs, as well as time to metastasis, progression-free survival, and time to symptomatic progression vs PBO (Smith, et al. NEJM 2018); overall survival (OS) results were immature. SPARTAN was unblinded upon meeting the primary end point; pts still on PBO were allowed to cross over to APA. Final survival results are reported herein. Methods: 1207 nmCRPC pts were randomized 2:1 to APA (240 mg QD) or PBO plus ongoing ADT. At progression, pts could receive open-label sponsor-provided abiraterone acetate + prednisone. After the primary efficacy end point (MFS) was met, 76 PBO pts (19%) crossed over to APA. OS and time to cytotoxic chemotherapy (TTCx) were tested by group sequential testing procedure with O’Brien-Fleming (OBF)-type alpha spending function. Time-to-event end points were analyzed by Kaplan-Meier method and Cox model. A sensitivity analysis for OS, accounting for crossover using a naïve censoring approach, was conducted. Results: With follow-up of 52.0 mo, 428 (of 427 required) OS events had occurred. Median treatment duration: APA, 32.9 mo; PBO, 11.5 mo. Median OS was significantly longer with APA + ADT vs PBO + ADT (73.9 vs 59.9 mo), (hazard ratio [HR], 0.784, Table). APA significantly lengthened TTCx (HR, 0.629). Discontinuation rates (APA vs PBO) due to progressive disease were 42.7% vs 73.9%, and due to adverse events (AE) 15.2% vs 8.4%. Safety was consistent with previous reports; grade 3/4 treatment-emergent (TE) AEs of special interest were rash 5.2%, fractures 4.9%, falls 2.7%, ischemic heart disease 2.6%, hypothyroidism 0%, and seizures 0%. 1 TEAE leading to death (myocardial infarction) was considered potentially APA related. Conclusions: In pts with nmCRPC, APA + ADT significantly improved OS compared with PBO + ADT, with median OS > 6 yr in the APA + ADT group and 14 mo improvement over PBO + ADT. Benefit from APA was observed despite a 19% crossover from PBO. The safety profile of APA was consistent with prior interim analyses. Clinical trial information: NCT01946204 . [Table: see text]

Correlation of Prostate-specific Antigen Kinetics with Overall Survival and Radiological Progression-free Survival in Metastatic Castration-sensitive Prostate Cancer Treated with Abiraterone Acetate plus Prednisone or Placebos Added to Androgen Deprivation Therapy: Post Hoc Analysis of Phase 3 LATITUDE Study

BACKGROUND

LATITUDE, a randomized, double-blind trial, compared abiraterone acetate and prednisone (AAP) + androgen deprivation therapy (ADT) versus placebo (PBO) + ADT in high-risk metastatic castration-sensitive prostate cancer (mCSPC).

OBJECTIVE

To assess the correlation of prostate-specific antigen (PSA) kinetics with overall survival (OS) and radiological progression-free survival (rPFS).

DESIGN, SETTING, AND PARTICIPANTS

A post hoc analysis of data from 597 men receiving AAP + ADT and 602 receiving PBO + ADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The associations of PSA-related outcomes (rates of confirmed 50% [PSA50] and 90% [PSA90] decline from baseline PSA [Prostate Cancer Working Group 2 criteria], rates of PSA < 0.2 ng/ml, median nadir PSA, time to PSA nadir [TPN], and time to PSA progression [TPP] with long-term outcomes [OS and rPFS]) were evaluated. Hazard ratios (HRs) were estimated using Cox proportional hazard model. Correlations of TPP with coprimary endpoints rPFS and OS were evaluated using Kendall's tau (KT).

RESULTS AND LIMITATIONS

AAP + ADT significantly delayed median TPP versus PBO + ADT (33.2 vs 7.4 mo; HR: 0.3, p <  0.001). TPP correlated with rPFS (KT = 0.921) and OS (KT = 0.666). In the AAP + ADT group, 91% had PSA50 and 79% had PSA90 responses (relative risk [RR]: 1.36 and 2.30, respectively; p <  0.001 for both comparisons vs PBO + ADT). Compared with nonresponders, PSA50 and PSA90 responders had reduced risk of death (RR: 0.44 and 0.12, respectively). At 6 mo, 40% receiving AAP + ADT and 6.5% receiving PBO + ADT achieved PSA ≤0.1 ng/ml, which was significantly associated with longer rPFS and OS. Median nadir PSA was 0.09 ng/ml with AAP + ADT versus 2.36 ng/ml with PBO + ADT. Median TPN (AAP + ADT, 6.4 mo; PBO + ADT, 3.8 mo) positively correlated with rPFS and OS.

CONCLUSIONS

Superior PSA response dynamics with AAP + ADT versus ADT + PBO strongly correlated with long-term outcomes of rPFS and OS in high-risk mCSPC.

PATIENT SUMMARY

We found that low prostate-specific antigen levels (≤0.1 ng/ml) after 6 mo may indicate a good long-term response to treatment. Our results need confirmation.

Erdafitinib in Locally Advanced or Metastatic Urothelial Carcinoma

BACKGROUND

Alterations in the gene encoding fibroblast growth factor receptor (FGFR) are common in urothelial carcinoma and may be associated with lower sensitivity to immune interventions. Erdafitinib, a tyrosine kinase inhibitor of FGFR1-4, has shown antitumor activity in preclinical models and in a phase 1 study involving patients with FGFR alterations.

METHODS

In this open-label, phase 2 study, we enrolled patients who had locally advanced and unresectable or metastatic urothelial carcinoma with prespecified FGFR alterations. All the patients had a history of disease progression during or after at least one course of chemotherapy or within 12 months after neoadjuvant or adjuvant chemotherapy. Prior immunotherapy was allowed. We initially randomly assigned the patients to receive erdafitinib in either an intermittent or a continuous regimen in the dose-selection phase of the study. On the basis of an interim analysis, the starting dose was set at 8 mg per day in a continuous regimen (selected-regimen group), with provision for a pharmacodynamically guided dose escalation to 9 mg. The primary end point was the objective response rate. Key secondary end points included progression-free survival, duration of response, and overall survival.

RESULTS

A total of 99 patients in the selected-regimen group received a median of five cycles of erdafitinib. Of these patients, 43% had received at least two previous courses of treatment, 79% had visceral metastases, and 53% had a creatinine clearance of less than 60 ml per minute. The rate of confirmed response to erdafitinib therapy was 40% (3% with a complete response and 37% with a partial response). Among the 22 patients who had undergone previous immunotherapy, the confirmed response rate was 59%. The median duration of progression-free survival was 5.5 months, and the median duration of overall survival was 13.8 months. Treatment-related adverse events of grade 3 or higher, which were managed mainly by dose adjustments, were reported in 46% of the patients; 13% of the patients discontinued treatment because of adverse events. There were no treatment-related deaths.

CONCLUSIONS

The use of erdafitinib was associated with an objective tumor response in 40% of previously treated patients who had locally advanced and unresectable or metastatic urothelial carcinoma with FGFR alterations. Treatment-related grade 3 or higher adverse events were reported in nearly half the patients. (Funded by Janssen Research and Development; BLC2001 ClinicalTrials.gov number, NCT02365597.).

Erdafitinib in high-risk patients (pts) with advanced urothelial carcinoma (UC)

4543

Background: The pan-FGFR inhibitor erdafitinib exhibited a robust objective response rate (ORR) and tolerability among pts with FGFR2/3-altered advanced UC in the BLC2001 (NCT02365597) phase 2 study (Siefker-Radtke ASCO 2018 #4503). Here we report a post hoc subgroup analysis to explore efficacy among high-risk pts. Methods: The analysis included 99 BLC2001 pts who received the optimized dose regimen of 8 mg/d continuous (pharmacodynamically guided uptitrated to 9 mg/d per serum phosphate). Results for ORR, duration of response (DOR), progression-free survival (PFS), and overall survival (OS) were analyzed by select baseline variables, with high-risk defined as age >75 y, ECOG PS 2, hemoglobin <10 g/dL, visceral metastases, and 2 or 3 Bellmunt risk factors. Results: Efficacy results (Table) show investigator-assessed ORR >36% and median PFS >5 mo across all subgroups except ECOG PS 2. OS data are immature but generally follow the trend of PFS. With the exception of ECOG 2, there were no differences in G3/4 serious AE proportions by subgroup. Conclusions: The post hoc subgroup findings support that erdafitinib generally provides comparable efficacy in high-risk pts with FGFR-altered advanced UC as the overall population. Clinical trial information: NCT02365597. [Table: see text]

Updated results of a phase IIa study to evaluate the clinical efficacy and safety of erdafitinib in Asian advanced cholangiocarcinoma (CCA) patients with FGFR alterations

4117

Background: Patients (pts) with advanced CCA who progressed on or after first line chemotherapy have no approved treatment options. Fibroblast growth factor receptor (FGFR) gene alterations are observed in many tumor types including 14-17% in CCA. Erdafitinib, an orally bioavailable, selective pan-FGFR kinase inhibitor, has shown clinical activity against solid tumors with FGFR alterations. Methods: LUC2001 is an open-label, multicenter, Ph2a study in advanced CCA pts with FGFR alterations (FoundationOne), who progressed after ≥ 1 prior treatment. The primary endpoint is objective response rate (ORR; RECIST 1.1). The secondary endpoints are disease control rate (DCR), progression free survival (PFS), duration of response (DOR), safety and pharmacokinetics (PK). Disease is evaluated every 8 weeks until disease progression (PD). Results: As of 3 Dec 2018, 222 CCA pts were molecularly screened; 34 had FGFR alterations, of whom 14 (8 FGFR2 fusion, 3 FGFR2 mutation, 1 FGFR3 fusion, 2 FGFR3 mutation) were dosed 8 mg once daily with up titration option. Median age was 51.5 years. 13/14 and 12/14 pts had prior platinum or gemcitabine based therapy respectively, 7/14 pts got re-treated with platinum or gemcitabine based therapy, and 9/14 pts had ≥2 prior lines of therapy. Median number of treatment cycles was 5.0 (range: 1; 22) and treatment duration was 4.83 (range: 0.5; 20.3) months. In 12 evaluable pts, there were 6 confirmed partial response (PR), 4 stable disease (SD) and 2 PD; ORR (CR+PR) was 6/12 (50.0%), DCR (CR+PR+uCR+uPR+SD) was 10/12 (83.3%); median DOR was 6.83 months (95% CI: 3.65; 12.16); median PFS was 5.59 months (95% CI: 1.87, 13.67). In 10 evaluable FGFR2+ pts, ORR was 6/10 (60.0%); DCR was 10/10(100%); median PFS was 12.35 months (95% CI: 3.15, 19.38). The most common TEAEs ( > 30%) were hyperphosphatemia, dry mouth, stomatitis, and dry skin. 9 pts had ≥ Grade 3 AEs (8 Grade 3,1 Grade 5), of which 7 drug related. TEAE led to treatment 1 discontinuation, 6 dose reductions and 1 death (not drug related). The results of PK and PK/PD relationship were consistent with other erdafitinib studies in different ethnic background pts. Conclusions: Asian advanced CCA pts with FGFR alterations treated with erdafitinib had encouraging efficacy and acceptable safety profile similar to experience in other tumor types and populations. Clinical trial information: NCT02699606.

FGFR-altered, advanced urothelial carcinoma (UC) and response to chemotherapy prior to receiving erdafitinib

4542

Background: FGFR-altered, advanced UC has predominantly a luminal 1 subtype, which is associated with lower response rates to immunotherapy and possibly also to chemotherapy. Objective response rates (ORR) for first-line cisplatin-based regimens, such as gemcitabine-cisplatin (gem/cis) and methotrexate-vinblastine-doxorubicin-cisplatin (MVAC), historically range between 45-60% and for gemcitabine-carboplatin (gem/carbo) 35-45%. However, the ORR on chemotherapy for the ~20% of patients with FGFR-altered tumors is unknown. Methods: BLC2001 (NCT02365597) is an ongoing global open-label phase 2 study of the pan-FGFR inhibitor erdafitinib in patients with locally advanced or metastatic UC with specific FGFR2/3 gene alterations. Patients who had received first-line (1L) or second-line (2L) chemotherapy for advanced UC were identified. Investigator-reported ORR (complete + partial responses) and median time to progression (TTP) on these pretreatments were analyzed. Results: Of 210 patients treated with erdafitinib in BLC2001, 191 had received prior systemic therapy including 184 and 83 patients who had received 1L and 2L chemotherapy, respectively. ORR were 29.3% (54/184; 95% CI 22.8%, 35.9%) to 1L chemotherapy and 24.1% (20/83; 95% CI 14.9%, 33.3%) to 2L chemotherapy. 1L therapy consisted of gem/cis in 94 patients, gem/carbo in 59 patients, and MVAC in 22 patients, with ORR (95% CI) of 35.1% (25.5%, 44.8%), 25.4% (14.3%, 36.5%), and 22.7% (5.2%, 40.2%), respectively. In the 2L setting, of 46 patients who had received a regimen containing a taxane (paclitaxel or docetaxel) or vinflunine, 8 patients (17.4%; 95% CI 6.4%, 28.3%) achieved an objective response. Median TTP was 7.16 mo (95% CI 6.18, 7.49) after 1L chemotherapy (7.6 mo for gem/cis, 6.3 mo for gem/carbo, and 5.3 mo for MVAC) and 4.35 mo (95% CI 3.3, 5.5) after 2L chemotherapy (3.6 mo for taxane or vinflunine). Conclusions: In this post-hoc analysis, the overall ORR to prior 1L chemotherapy was lower, but within the range expected based on historical data. Further investigation into the response to chemotherapy in FGFR alteration positive patients is warranted and may be useful for the development of 1L trials of combination therapy. Clinical trial information: NCT02365597.

Analysis of FGFR alterations from circulating tumor DNA (ctDNA) and Tissue in a phase II trial of erdafitinib in urothelial carcinoma (UC)

420

Background: Plasma samples from a Phase 2 study of the pan-FGFR inhibitor erdafitinib in advanced UC patients (pts) with FGFR mutations (mut) or fusions, were tested using next generation sequencing (NGS) for circulating tumor DNA (ctDNA), and results compared to central FGFR status determination from tissue. Methods: FGFR alterations were measured in archival tissue using an RNA-based RT-PCR test and compared with FGFR alterations identified in pre-treatment plasma specimens using the Guardant360 ctDNA test. Sensitivity of the ctDNA test to detect the FGFR alterations identified by RT-PCR from tissue, the proportion of pts with a study-eligible FGFR alteration in ctDNA, and the ability to detect a tissue FGFR alteration in ctDNA in relation to clinical response were assessed. Results: Samples from 155 pts with detectable baseline ctDNA were included. Overall, concordance between ctDNA and tissue-based FGFR results was 56% (87/155): 63% (77/122) for tissue mut-positive pts vs 24% (7/29) in fusion-positive pts. 61% of pts (94/155) were positive for a study-eligible FGFR alteration from blood-based testing in the tissue-positive population. The response rate was 47% (36/77) for patients for which FGFR mutations could be detected in blood (ctDNA- FGFR-positive) compared with 32% (14/44) in patients for which mutations were not detected in blood (ctDNA- FGFR-negative), with an estimated odds ratio of 1.882 (95% CI: 0.866; 4.090) Conclusions: The 63% concordance rate for detecting FGFR mut in temporally unmatched blood and tissue supports potential for patient selection with blood-based testing, while ctDNA FGFR fusion detection may require further optimization. Although differences in clinical response rate were observed between ctDNA- FGFR-positive and negative patients, the results were not statistically significant. Importantly, a proportion of ctDNA-negative pts responded to erdafitinib, indicating that tissue-based testing may be warranted for pts negative for FGFR alterations via blood-based testing. (BLC2001, NCT02365597). Clinical trial information: NCT02365597.

Predictive value of fibroblast growth factor receptor (FGFR) mutations and gene fusions on anti-PD-(L)1 treatment outcomes in patients (pts) with advanced urothelial cancer (UC)

419

Background: FGFR alterations have been shown to be associated with immunologically “cold” UC tumors with low immune marker expression and T cell infiltrate, a poorly receptive environment for immune checkpoint inhibitors. Using a real world matched clinical and genomic dataset of pts with advanced UC, we explored their predictive value in pts receiving anti-PD-(L)1 therapy. Methods: The Flatiron Health-Foundation Medicine Clinico-Genomic Database (CGDB) contained full clinical and treatment information and molecular data on a cohort of pts with confirmed advanced UC. The populations of interest are FGFR+ and FGFR- patients determined by the presence or absence of a prespecified panel of FGFR2/3 mutations and fusions. Overall survival (OS), measured from the start of anti-PD-(L)1 therapy, was analyzed using Kaplan-Meier estimation and Cox proportional hazards models adjusted for left truncation (delayed entry model). Results: 118 pts ( FGFR+ n = 26, FGFR- n = 92) treated with anti-PD-(L)1 therapy for advanced UC were assessed for OS. Median OS for FGFR+ pts who received any line of anti-PD-(L)1 therapy (n = 26) was 3.1 mo vs 6.1 mo for FGFR- pts (n = 92) (hazard ratio [HR] 1.33, 95% CI 0.78-2.26, p = 0.30). For first-line anti-PD-(L)1 therapy, median OS in FGFR+ pts (n = 12) was 4.7 mo vs 11.3 mo for FGFR- pts (n = 28) (HR 1.94, 95% CI: 0.78-4.82, p = 0.15); median OS in second-line were 3.1 mo (n = 12) vs 6.1 mo (n = 47), respectively (HR 1.17, 95% CI 0.53-2.59, p = 0.70). Per multivariate analysis, FGFR+ status appears to be associated with poorer OS in pts treated with any line of anti-PD-(L)1 therapy (HR 1.25, 95% CI 0.71-2.21, p = 0.43). Conclusions: These real-world data suggest that FGFR+ pts following anti-PD-(L)1 therapy for advanced UC may be associated with a trend in poorer overall survival outcome compared with FGFR- pts. These findings are in alignment with treatment history data from BLC2001 (Siefker-Radtke A, et al. ASCO-GU 2018), which showed low response rates to prior anti-PD-(L)1 therapies among FGFR+ pts.

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

182

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

193

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.