Prostate-specific antigen (PSA) kinetics in patients (pts) with advanced prostate cancer treated with apalutamide: Results from the TITAN and SPARTAN studies

5541

Background: The phase III TITAN and SPARTAN studies demonstrated improved outcomes with the addition of apalutamide (APA) to androgen deprivation therapy (ADT); outcomes included prolonging overall survival and radiographic progression-free survival (rPFS) in metastatic castration-sensitive prostate cancer (mCSPC) in TITAN, and metastasis-free survival (MFS) in nonmetastatic castration-resistant PC (nmCRPC) in SPARTAN. A post hoc analysis of PSA kinetics in pts from both studies is reported. Methods: Baseline PSA at randomization, time to PSA nadir, and proportion of pts achieving a PSA decline of ≥ 90% (PSA90) and of pts achieving a PSA ≤ 0.2 ng/mL at 3 and 12 months and at any time after treatment in the APA arms of the TITAN and SPARTAN studies were evaluated. Within each study, rPFS/MFS were compared between pts achieving a PSA90 or PSA ≤ 0.2 ng/mL response vs not. Results: 525 TITAN pts and 806 SPARTAN pts treated with APA were included in the analysis. Median baseline PSA, time to PSA nadir, median PSA nadir, and maximum percentage changes from baseline PSA are shown in the table. PSA90 and confirmed PSA ≤ 0.2 ng/mL were evident as early as 3 months in both TITAN and SPARTAN, and percentage of confirmed response continued to increase at 12 months. Pts treated with APA who achieved PSA90 were at lower risk of rPFS events in TITAN and of MFS events in SPARTAN, with a hazard ratio (95% confidence interval) of 0.46 (0.321-0.653) and 0.36 (0.271-0.489) in each respective study (both p < 0.0001), compared with APA pts who did not achieve PSA90. Pts with confirmed PSA ≤ 0.2 ng/mL had similar rPFS and MFS benefits. Conclusions: Pts with advanced PC, whether mCSPC or nmCRPC, treated with APA + ADT demonstrated rapid PSA declines that continued over time. There was a high rate of pts with PSA90 and with PSA ≤ 0.2 ng/mL responses, with a majority of pts reaching PSA90 by 12 months. Pts achieving PSA90 and/or PSA nadir of ≤ 0.2 ng/mL had a prolonged rPFS and MFS in TITAN and SPARTAN, respectively. Clinical trial information: NCT02489318; NCT01946204 . [Table: see text]

Association of detectable levels of circulating tumor DNA (ctDNA) with disease burden in prostate cancer (PC)

5562

Background: PC is characterized by a relatively low prevalence of recurrent somatic point mutations. ctDNA is shed from PC and can be analyzed to profile somatic point mutations and copy number changes. We evaluated a computational approach to detect ctDNA (ie. ctDNA+) in PC based on allele frequencies of polymorphisms and mutations. We then sought to confirm the association of this biomarker with disease burden and clinical outcome. Methods: Customized, hybrid capture, high-depth next-generation sequencing was performed on pre-treatment (PT) plasma samples from a phase 2 line 3+ metastatic castration-resistant PC (mCRPC) study (NCT02854436, GALAHAD) and PT and end of treatment (EOT) samples from randomized Phase 3 study in non-metastatic (nm) CRPC (NCT01946204, SPARTAN) and from metastatic castration-sensitive PC (mCSPC) (NCT02489318, TITAN). Associations of ctDNA+ with bone lesions (number), visceral metastases (+/-), circulating tumor cells count (CTCc), and serum prostate specific antigen (PSA), alkaline phosphatase (AP) and lactate dehydrogenase (LD) were tested. Also, associations of ctDNA+ with overall survival (OS) and second progression free survival (PFS2) were evaluated in randomized studies using Cox regression. Results: ctDNA+ at PT was 7.5% in nmCRPC, 23.7% in mCSPC and 66% in heavily pre-treated mCRPC. ctDNA+ increased from PT to EOT in nmCRPC (7.5% to 27%) and mCSPC (23.7% to 63.6%). Disease burden metrics were evaluated in ctDNA+ vs ctDNA- patients. ctDNA+ was associated with higher disease burden in mCRPC (Table), nmCRPC and mCSPC. At EOT, ctDNA+ patients had shorter OS and PFS2 in nmCRPC (HR [95% CI] OS: 2.73 [1.83, 4.08], p < 0.0001; PFS2: 2.00 [1.38, 2.90], p = 0.0002) and mCSPC (HR [95% CI] OS: 7.59 [3.22, 17.91], p < 0.0001; PFS2: 4.84 [2.47, 9.47], p < 0.0001). Conclusions: ctDNA+ assessed using our novel, composite biomarker increases with advanced disease state and disease progression, is significantly associated with disease burden and poor clinical outcome in PC and could be a clinically relevant metric for monitoring response to therapy. Clinical trial information: NCT02854436 . [Table: see text]

Molecular determinants of prostate specific antigen (PSA) kinetics and clinical response to apalutamide (APA) in patients (pts) with nonmetastatic castration-resistant prostate cancer (nmCRPC) in SPARTAN

5521

Background: In SPARTAN, APA + androgen deprivation therapy (ADT) prolonged metastasis-free survival (MFS) and improved PSA kinetics over placebo (PBO) + ADT in high-risk nmCRPC. All molecular subtypes derived benefit in MFS from APA (Feng FY, et al. ASCO GU 2019; abstract 42). We evaluated the association of PSA decline and efficacy outcomes in SPARTAN pts with different molecular subtypes. Methods: Gene expression from archival primary tumors (biomarker population) was assessed with the DECIPHER platform (Decipher Biosciences, Inc.) and stratified into genomic classifier (GC) high- and low-to-average risk using GC score > 0.6 and ≤ 0.6, respectively, and ADT-resistant or -sensitive basal or luminal A/B (PAM50 classifier) subtypes. PSA nadir and confirmed PSA decline (Table) were assessed in APA pts overall and at 3, 6, and 12 mo. Associations between molecular subtypes and outcomes were assessed. Results: Of 233 available samples, 154 were from APA pts; 49% of APA pts had high GC score and 66% had basal subtype. PSA levels at baseline were similar across all subtypes. Regardless of GC score or basal/luminal subtype, > 50% of patients achieved ≥ 90% reduction in PSA with APA. PSA declined faster and PSA reduction was deeper at 6 mo (Table) in GC low to average vs GC high risk and luminal vs basal subtypes. Overall, only luminal vs basal subtypes had a significantly higher % of pts with ≥ 90% PSA decline (Chi square p = 0.037). In luminal pts, deeper PSA decline with APA was consistent with improved MFS vs basal pts. In GC high pts, MFS benefit with APA was similar to that in GC low to average pts despite lower PSA decline. Although GC low to average and luminal pts had more rapid and deeper PSA responses than GC high or basal pts, respectively, all pts derived MFS benefit. Association of long-term outcomes with PSA decline in these molecular subtypes will be presented. Conclusions: In SPARTAN, all molecular subtypes of pts with nmCRPC treated with APA + ADT had MFS benefit and rapid and sustained PSA decline. PSA responses were deepest and most rapid in GC low to average and luminal subtypes. Clinical trial information: NCT01946204 . [Table: see text]

A phase II trial of cabozantinib in hormone receptor-positive breast cancer with bone metastases

1062

Background: We assessed the antitumor activity of cabozantinib, a potent multi-receptor oral tyrosine kinase inhibitor with activity against MET, RET, VEGFR2, and AXL, in patients with hormone-receptor positive (HR+) breast cancer with bone metastases. Methods: In this single-arm multicenter phase II study, patients with HR+, HER2- metastatic breast cancer and ≥ 1 prior line of therapy received an initial starting dose of 100 mg cabozantinib, later reduced to 60 mg per day. The primary endpoint was bone scan response rate determined by independent central review and defined as percent change of bone scan area from baseline. The target bone scan response rate was 30% compared to a null response rate of 10%. Secondary endpoints included objective response rate (ORR) by RECIST v1.1, progression free (PFS) and overall survival (OS). Bone scan and CT were obtained every 12 weeks. Results: Among 52 enrolled patients, median age was 55, and 54% and 42% had > 2 lines prior endocrine and chemotherapy, respectively and 18 (35%) had bone-only disease. 20 (38%) experienced a partial bone scan response and 6 (12%) had stable disease (SD). 16 (31%) patients discontinued study prior to week 12 assessment for early clinical progression or toxicity, and three (6%) had missing follow-up scans. Best extra-osseous overall response revealed SD in 26 (50%), but no objective responses. In 25 patients with bone scan disease control at 12 weeks, only 3 (12%) developed extra-osseous progression. Median PFS was 4.3 months (90% CI 2.8 - 5.5) and OS was 19.6 months (90% CI 18.0 – 26.8). In a landmark analysis, patients with bone scan disease control at 12 weeks had longer OS (median 24.2 months, 90% CI 16.4 – 31.7) than those without (median OS 13.3 months, 90% CI 9.5 – 18.2), with a hazard ratio of 0.37 (90% CI 0.21 – 0.65). Most common grade 3 or 4 toxicities were hypertension (10%), anorexia (6%), diarrhea (6%), fatigue (4%) and hypophosphatemia (4%). Dose reduction or delay occurred in 42 (81%) patients. Conclusions: This study met its primary endpoint with bone scans improved in 38% of patients with metastatic HR+ breast cancer and remained stable in an additional 12% with cabozantinib treatment. Bone scan response correlated with improved OS. This is the first reported study in breast cancer to use bone scan response as a primary endpoint. Further studies with cabozantinib in HR+ breast cancer and additional validation of bone scan response as a surrogate for clinical benefit in breast cancer are warranted. Clinical trial information: NCT01441947 .

A phase III randomized, placebo-controlled, double-blind study of niraparib plus abiraterone acetate and prednisone versus abiraterone acetate and prednisone in patients with metastatic prostate cancer (MAGNITUDE)

TPS5588

Background: Preclinical data suggest synergistic antitumor activity when the PARP inhibitor (PARPi) niraparib is combined with the androgen pathway inhibitor abiraterone acetate1. The addition of a PARPi to abiraterone acetate plus prednisone (AAP) showed improved radiographic progression-free survival (rPFS) vs AAP alone in patients with mCRPC regardless of DNA repair gene defect (DRD) status2. Interim results from a phase I study support safety and tolerability of niraparib 200 mg combined with AAP in patients with mCRPC3. The objective of this Phase III study is to compare the efficacy and safety of niraparib plus AAP versus AAP with placebo as first-line therapy for mCRPC. Methods: This ongoing multicenter MAGNITUDE study (NCT03748641) will open in approximately 300 sites across 28 countries and will enroll patients with mCRPC who have not received treatment in the metastatic castrate resistant setting other than ongoing androgen deprivation therapy [ADT] and ≤4 months of AAP. DRD status will be determined by plasma and tissue assays. The cohort with DRD (n=400) and the cohort without DRD (n=600) will each be randomized 1:1 to niraparib + AAP or placebo + AAP. The first patient was consented in February 2019 and enrollment is ongoing. The primary objective of the study is to compare radiographic progression-free survival (rPFS) as assessed by blinded independent central radiology review in each cohort and treatment group. To test superiority of the combination vs AAP, sample sizes were estimated to provide 92% power to detect HR≤0.65 rPFS in the cohort with DRD and 94% power to detect HR≤0.67 in rPFS in the cohort without DRD, both at a 2-tailed level of significance of 0.05. The secondary objectives are time to symptomatic progression, time to cytotoxic chemotherapy, and overall survival. Safety and pharmacokinetic profiles will be evaluated. 1Rajendra N, et al. Cancer Res 2019;79(13 Suppl):Abstract nr 2134. 2Clarke N, et al. Lancet Oncol. 2018;(7):975-986. 3Saad, et al. Ann Oncol, 2018;29 (suppl 8), mdy284.043, https://doi.org/10.1093/annonc/mdy284.043 ) Clinical trial information: NCT03748641 .

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]

Niraparib in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) and biallelic DNA-repair gene defects (DRD): Correlative measures of tumor response in phase II GALAHAD study

118

Background: Niraparib, a highly potent and selective poly (ADP-ribose) polymerase inhibitor (PARPi) received breakthrough designation by US FDA for treatment of pts with BRCA1,2 mutant mCRPC who progressed on taxane and androgen receptor-targeted therapy. Circulating tumor cells (CTC) detection associates with poor outcomes, with declining counts consistent with improved survival [1,2]. Methods: GALAHAD study assessed niraparib (300 mg daily) in pts with mCRPC+DRD (NCT02854436). Patients with non-measurable soft tissue disease by RECIST 1.1 were required to have a baseline CTC count ≥1 cell/7.5 mL blood. CTC response was defined as CTC conversion to <5 for pts with baseline CTC≥5 and CTC drop to 0 post-baseline for pts with ≥1 baseline CTC. Alkaline phosphatase (ALP) was collected at each monthly cycle. Results: For primary efficacy population of pts with BRCA1/2 mutations, the objective response rate (ORR) by RECIST 1.1 criteria was 41.4%. CTC response rates for this population were as high as ORR regardless of measurability (Table). Time to CTC response for each CTC responder will be shown. Radiographic progression-free survival (rPFS) durations were similar for patients with a measurable disease response and patients with CTC conversion. Median duration of treatment for responders of any type was 6.7mo (range: 2–27). DRD status, both BRCA and non- BRCA, for each responder will also be discussed. Trends in disease burden and markers of bone metabolism will also be quantitatively explored including 24% pts who were on treatment for at least one cycle who had ≥25% decreased unfractionated ALP from baseline. Conclusions: Niraparib showed clinical activity with CTC response and decline in ALP levels in mCRPC pts having biallelic BRCA mutations, which further supports its recent breakthrough designation. Clinical trial information: NCT02854436. [Table: see text]

Clinical outcomes and patient (pt) profiles in REASSURE: An observational study of radium-223 (Ra-223) in metastatic castration-resistant prostate cancer (mCRPC)

32

Background: Ra-223 is a targeted alpha therapy that showed a survival advantage and favorable safety profile in the phase 3 ALSYMPCA trial in pts with mCRPC. REASSURE (NCT02141438) is evaluating the long-term safety of Ra-223 in routine clinical practice in pts with mCRPC over a 7-year follow-up period. Methods: In this global, prospective, single-arm, observational study, the second prespecified interim analysis (data cut-off March 2019) evaluated safety and clinical outcomes of Ra-223 in pts with mCRPC. Primary outcome measures were incidence of second primary malignancies (SPM), bone marrow suppression and short- and long-term safety in pts who had ≥1 Ra-223 dose. Secondary outcomes included overall survival (OS). Results: For 1465 pts in the safety analysis, median follow up was 11.5 months. Median PSA (n=1053), ALP (n=1048), and LDH (n=555) levels at baseline were 59 ng/mL, 135 U/L, and 269 U/L, respectively. 81% of pts had bone metastases only at baseline; 19% of pts had other metastatic sites, mostly in the lymph nodes. 19% of pts had <6 metastatic sites, 47% had 6–20 sites, 20% had >20 lesions but not a superscan, and 6% had a superscan. 45%, 38%, 37%, 9%, and 8% of pts received prior abiraterone, docetaxel, enzalutamide, cabazitaxel, or sipuleucel-T as prior therapies, respectively. Median number of Ra-223 doses received was 6; 67% of pts had ≥5 doses. SPM occurred in 1% of pts. The most common treatment-emergent drug-related adverse event (AE) of any grade was diarrhea (11%). 10% of pts had a bone-associated event, 5% had fractures, and 15% had a hematological AE. Median OS was 15.6 months (95% CI 14.6–16.5). Conclusions: In REASSURE, there was a low incidence of SPM, bone fractures, and bone marrow suppression after Ra-223 treatment, with no new AEs identified. This study confirms that in routine clinical practice, Ra-223 AE rates were low, and pts generally received ≥5 doses. Clinical trial information: NCT02141438. [Table: see text]

A phase III randomized, placebo-controlled, double-blind study of niraparib plus abiraterone acetate and prednisone versus abiraterone acetate and prednisone in patients with metastatic prostate cancer (NCT03748641)

TPS257

Background: Preclinical data suggest synergistic antitumor activity when the PARP inhibitor (PARPi) niraparib is combined with the androgen pathway inhibitor abiraterone acetate. (1) The addition of a PARPi to abiraterone acetate plus prednisone (AAP) showed improved radiographic progression-free survival (rPFS) vs AAP alone in patients with mCRPC regardless of DNA repair gene defect (DRD) status. (2) Interim results from a phase 1 study support safety and tolerability of niraparib 200 mg combined with AAP in patients with mCRPC. (3) The objective of this Phase 3 study is to compare the efficacy and safety of niraparib plus AAP versus AAP with placebo as first-line therapy for mCRPC. Methods: This ongoing multicenter MAGNITUDE study will open in 300 sites across 28 countries and will enroll patients with mCRPC who have not received treatment in the metastatic castrate resistant setting other than ongoing androgen deprivation therapy [ADT] and ≤4 months of AAP. The DRD positive cohort (Cohort 1, n=400) will comprise patients whose tumors have DRD, as determined by a previously validated plasma or tissue assay. The cohort without DRD (Cohort 2, n=600) will enroll patients whose tumors are not found to have DRD. Enrollment began in February 2019. The primary objective of the study is to compare radiographic progression-free survival (rPFS) as assessed by blinded independent central radiology review for patients treated with niraparib and AAP versus placebo and AAP. To test superiority of the combination vs AAP, sample sizes were estimated to provide 92% power to detect HR≤0.65 rPFS in the DRD positive cohort and 94% power to detect HR≤0.67 in rPFS in the cohort without DRD, both at a 2-tailed level of significance of 0.05. The main secondary objectives are time to symptomatic progression, time to cytotoxic chemotherapy, and overall survival. Safety and pharmacokinetic profiles will be evaluated.1) Rajendra N, et al. Cancer Res 2019;79 (13 Suppl): Abstract nr 2134. 2) Clarke N, et al. Lancet Oncol. 2018;(7):975-986. 3) Saad, et al. Ann Oncol, 2018;29 (suppl 8), mdy284.043, https://doi.org/10.1093/annonc/mdy284.043 ). Clinical trial information: NCT03748641.

Apalutamide and overall survival in non-metastatic castration-resistant prostate cancer

BACKGROUND

In the SPARTAN study, compared with placebo, apalutamide added to ongoing androgen deprivation therapy significantly prolonged metastasis-free survival (MFS) and time to symptomatic progression in patients with high-risk non-metastatic castration-resistant prostate cancer (nmCRPC). Overall survival (OS) results at the first interim analysis (IA1) were immature, with 104 of 427 (24%) events required for planned final OS analysis. Here, we report the results of a second pre-specified interim analysis (IA2).

METHODS

One thousand two hundred and seven patients with nmCRPC were randomized 2 : 1 to apalutamide (240 mg daily) or placebo. The primary end point of the study was MFS. Subsequent therapy for metastatic CRPC was permitted. When the primary end point was met, the study was unblinded. Patients receiving placebo who had not yet developed metastases were offered open-label apalutamide. At IA2, pre-specified analysis of OS was undertaken, using a group-sequential testing procedure with O'Brien-Fleming-type alpha spending function. Safety and second progression-free survival (PFS2) were assessed.

RESULTS

Median follow-up was 41 months. With 285 (67% of required) OS events, apalutamide was associated with an improved OS compared with placebo (HR 0.75; 95% CI 0.59-0.96; P = 0.0197), although the P-value did not cross the pre-specified O'Brien-Fleming boundary of 0.0121. Apalutamide improved PFS2 (HR 0.55; 95% CI 0.45-0.68). At IA2, 69% of placebo-treated and 40% of apalutamide-treated patients had received subsequent life-prolonging therapy for metastatic CRPC. No new safety signals were observed.

CONCLUSION

In patients with nmCRPC, apalutamide was associated with a 25% reduction in risk of death compared with placebo. This OS benefit was observed despite crossover of placebo-treated patients and higher rates of subsequent life-prolonging therapy for the placebo group.

Bacterial community structure and response to nitrogen amendments in Lake Shenandoah (VA, USA)

Microbial processes are critical to the function of freshwater ecosystems, yet we still do not fully understand the factors that shape freshwater microbial communities. Furthermore, freshwater ecosystems are particularly susceptible to effects of environmental change, including influx of exogenous nutrients such as nitrogen and phosphorus. To evaluate the impact of nitrogen loading on the microbial community structure of shallow freshwater lakes, water samples collected from Lake Shenandoah (Virginia, USA) were incubated with two concentrations of either ammonium, nitrate, or urea as a nitrogen source. The potential impact of these nitrogen compounds on the bacterial community structure was assessed via 16S rRNA amplicon sequencing. At the phylum level, the dominant taxa in Lake Shenandoah were comprised of Actinobacteria and Proteobacteria, which were not affected by exposure to the various nitrogen treatments. Overall, there was not a significant shift in the diversity of the bacterial community of Lake Shenandoah with the addition of nitrogen sources, indicating this shallow system may be constrained by other environmental factors.

The use of the Körperkoordinationstest für Kinder in the talent pathway in youth athletes: A systematic review

OBJECTIVES

Identifying talented athletes from an early age to accelerate their development requires the investment of substantial resources. Due to the need for multifactorial approaches to talent identification, motor competence assessments are increasingly prevalent in contemporary testing batteries. Therefore, the aim of this review was to evaluate the literature on the use of a product-oriented motor competence assessment tool, the Körperkoordinationstest für Kinder (KTK) in the talent pathway and determine whether it is warranted in such programs.

METHODS

Three electronic databases (i.e. PubMed, SPORTDiscus and Web of Science) were searched for studies that used at least one component of the KTK to assess motor competence for talent detection, identification, development and selection in athletic populations. A total of 21 articles were included in the review, of which seven used the full version of the KTK and 14 used modified versions or individual components of the battery. The quality of included studies was assessed using a modified version of the Joanna Brigg's Institute Critical Appraisal Checklist.

RESULTS

The analysed literature suggests that the KTK can successfully distinguish between athletes of different competition levels and across different sporting domains, however, findings should be interpreted with caution due to the cross-sectional nature of the studies. Furthermore, the moving sideways subtest displayed the greatest discriminative power for athletes of different competition levels. Motor competence was not affected by maturation and did not differ between genders or playing positions.

CONCLUSIONS

Collectively, these findings suggest that the KTK is a useful motor competence assessment in the talent pathway.

Impact of darolutamide (DARO) on pain and quality of life (QoL) in patients (Pts) with nonmetastatic castrate-resistant prostate cancer (nmCRPC)

5000

Background: DARO is a structurally distinct androgen receptor antagonist for which in vitro and phase 1/2 studies suggest low risk of adverse events (AEs) and drug–drug interaction. In the ARAMIS study of DARO in nmCRPC, metastasis-free survival (MFS) was significantly prolonged vs placebo (PBO) (40.4 vs 18.4 mo; hazard ratio [HR] 0.41; 95% confidence interval [CI] 0.34–0.50; P < 0.001) and interim overall survival (OS) favored DARO (HR 0.71; 95% CI 0.50–0.99; P = 0.045). Methods: 1509 pts were randomized 2:1 to DARO 600 mg (two 300 mg tablets) twice daily (n = 955) or PBO (n = 554) while continuing androgen deprivation therapy (ADT). Primary endpoint was MFS. Secondary endpoints included OS and time to pain progression (assessed by Brief Pain Inventory Short Form). QoL was assessed by European Organisation for Research and Treatment of Cancer QoL Prostate Cancer module (EORTC-QLQ-PR25) at baseline (BL) and every 16 wks until end of treatment. Analysis of time to deterioration in EORTC-QLQ-PR25 subscales, defined as first occurrence of a minimally important difference (half the standard deviation of BL value), used Kaplan–Meier estimators and stratified Cox proportional hazard models. Results: DARO significantly delayed pain progression vs PBO (40.3 vs 25.4 mo; HR 0.65; 95% CI 0.53–0.79; P < 0.001); this was maintained beyond end of study treatment. Time to deterioration of EORTC-QLQ-PR25 outcomes showed statistically and clinically significant delays with DARO vs PBO for urinary symptoms (25.8 vs 14.8 mo; HR 0.64; 95% CI 0.54–0.76; P < 0.01). Time to deterioration of hormonal treatment-related symptoms was comparable with DARO vs PBO (18.9 vs 18.4 mo; HR 1.06; 95% CI 0.88–1.27; P = 0.52). DARO was well tolerated. Exposure-adjusted incidences (pts per 100 years’ exposure) of AEs of interest were similar/lower with DARO vs PBO (fatigue/asthenic conditions [11.3 vs 11.1], hypertension [4.7 vs 5.1], hot flush [3.7 vs 4.1], fracture [3.0 vs 3.5], falls [2.7 vs 4.1], cognitive disorder [0.3 vs 0.2], and seizure [0.2 vs 0.2]). Conclusions: For nmCRPC pts, DARO prolongs MFS, is well tolerated, maintains QoL, and delays worsening of pain and disease-related symptoms compared with PBO. Clinical trial information: NCT02200614.

Efficacy of apalutamide (APA) plus ongoing androgen deprivation therapy (ADT) in patients (pts) with nonmetastatic castration-resistant prostate cancer (nmCRPC) and baseline (BL) comorbidities (CM)

5023

Background: The addition of APA to ongoing ADT in pts with nmCRPC significantly prolonged metastasis-free survival (MFS), time to symptomatic progression (SymProg), and second progression-free survival (PFS2) in SPARTAN. We assessed the impact of APA on these end points in pts with or without BL CM. Methods: Using Cox proportional hazards models, treatment effect of APA was evaluated in SPARTAN pts with CM at BL, stratifying by the presence of BL diabetes/hyperglycemia (D/H), cardiovascular disease (CVD), hypertension (HTN), and renal insufficiency (RI). Results: Of 1207 SPARTAN pts, 1062 (88%) had ≥ 1 BL CM, including 703/806 (87%) APA pts and 359/401 (90%) PBO pts. A total of 226 (19%), 398 (33%), 798 (66%), and 774 (64%) pts had D/H, CVD, HTN, and RI, respectively; 323 (27%), 412 (34%), 259 (21%), and 68 (6%) pts had 1, 2, 3, and 4 CM, respectively. Incidence of CM was balanced between arms. Pts with CM were older than pts with no CM (median age, 75 vs 69 yrs, APA; 74 vs 69 yrs, PBO). MFS, SymProg, and PFS2 benefit with APA was significant in all CM subgroups, except PFS2 for pts with D/H (Table) and regardless of the number of CM. The incidence of any treatment-emergent AE was balanced between pts with and without CM. AEs with APA were not affected by any CM. Clinical trial information: NCT01946204. Conclusions: The benefit of APA + ongoing ADT in pts with nmCRPC was maintained in pts with D/H, CVD, HTN, and RI. The safety profile of APA was not affected by any CM.[Table: see text]

Predictors of falls and fractures in patients (pts) with nonmetastatic castration-resistant prostate cancer (nmCRPC) treated with apalutamide (APA) plus ongoing androgen deprivation therapy (ADT)

5025

Background: SPARTAN, a phase 3 study of APA vs placebo (PBO) added to ongoing ADT in pts with nmCRPC, demonstrated that APA significantly prolongs metastasis-free survival, time to symptomatic progression, and second progression free survival (Smith et al. NEJM 2018), with no decline in health-related quality of life (Saad et al. Lancet Oncol 2018). SPARTAN pts who received APA, vs PBO, with ongoing ADT had higher rates of falls (15.6% vs 9.0%) and fractures (11.7% vs 6.5%). An analysis was performed to identify clinical characteristics associated with falls and fractures in APA-treated SPARTAN pts. Methods: Of 1207 pts enrolled, 806 were randomized to APA. Univariate Cox proportional hazards model (UVA) assessed the association of 47 baseline clinical characteristics (demographics, comorbidities, and medication use, including bone-sparing agents) with time to fall or time to fracture. Characteristics with p values < 0.10 were included in a multivariate Cox proportional hazards model (MVA) to determine independent factors associated with these outcomes (p < 0.05). Results: Factors associated with time to both fall and fracture on UVA (p < 0.10) included older age, low serum albumin, and poor ECOG performance status (PS). Additional factors associated with time to fall were cerebrovascular accidents/transient ischemic attacks, neuropathy, depression, α-blocker use, and antidepressant use. On MVA, older age, poor ECOG PS, history of neuropathy, and α-blocker use were independently associated with falls; older age and low serum albumin were independently associated with fractures (Table). Conclusions: At initiation of APA added to ongoing ADT, nmCRPC pts with higher risk of falls and fractures can be identified and are candidates for intervention to reduce the risk for these events. Clinical trial information: NCT01946204. [Table: see text]

Age-related efficacy and safety of apalutamide (APA) plus ongoing androgen deprivation therapy (ADT) in subgroups of patients (pts) with nonmetastatic castration-resistant prostate cancer (nmCRPC): Post hoc analysis of SPARTAN

5024

Background: SPARTAN, a randomized phase 3 placebo (PBO)-controlled study in pts with high-risk nmCRPC and PSA doubling time ≤ 10 mo, showed that, compared with PBO, addition of APA to ongoing ADT treatment (tx) prolonged metastasis-free survival (MFS) by > 2 y, reduced the risk of symptomatic progression by 55%, and increased second progression-free survival (PFS2), which is the time from randomization to disease progression on first subsequent anticancer tx, or death. The impact of APA in terms of benefit and safety profile was evaluated in pts aged < 65, 65-74, and ≥ 75 y. Methods: Pts with nmCRPC were randomized 2:1 to APA (240 mg QD) or PBO; ADT was continuous. APA effect was analyzed by Cox models and Kaplan-Meier methods across age subgroups. Results: Baseline characteristics among age groups were similar, although ECOG PS 1 vs 0 increased with age. MFS benefit with APA was highly significant for all age subgroups (Table). In pts ≥ 75 y, MFS risk with APA vs PBO was reduced by 59%; MFS risk was reduced by 86% and 76% for pts < 65 and 65-74 y, respectively. Risk of PFS2 with APA vs PBO was reduced across all age subgroups. PFS2 in pts < 65, 65-74, and ≥ 75 y: HR, 0.09 (p < 0.0001); HR, 0.56 (p = 0.0343); HR, 0.59 (p = 0.0092), respectively. Risk of symptomatic progression was lessened with APA vs PBO for all age subgroups (Table). There was a similar increase in incidence of tx-emergent adverse events (TEAE) with age in both tx arms that remained higher with APA. Incidence of grade 3/4 TEAE (≥ 75 vs < 65 y): APA, 50% vs 37%; PBO, 37% vs 28%. Conclusions: Pts in all age subgroups with high-risk nmCRPC had significant improvement in MFS with APA + ongoing ADT. The safety profile of APA was similar across age subgroups. Clinical trial information: NCT01946204. [Table: see text]

Identifying molecular determinants of response to apalutamide (APA) in patients (pts) with nonmetastatic castration-resistant prostate cancer (nmCRPC) in the SPARTAN trial

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Background: The SPARTAN trial recently demonstrated that addition of APA to androgen deprivation therapy (ADT) improved metastasis-free survival (MFS) and second progression-free survival (PFS2) in nmCRPC pts. We performed transcriptome-wide profiling of available primary tumor samples from pts in SPARTAN to evaluate potential biomarkers of response or resistance to APA+ADT. Methods: Pts included in SPARTAN were at high risk of developing metastasis.We used a commercially available genomic assay (DECIPHER prostate test, GenomeDx Biosciences, Inc., San Diego, CA) to assess gene expression in 233 archived primary tumors from SPARTAN pts. Using a Cox proportional hazard model, we assessed the association between scores and subtypes from previously derived prognostic and predictive gene signatures, such as DECIPHER and basal (BA) vs luminal (LU) subtyping. Results: Pts with high DECIPHER scores had greater treatment effect with APA+ADT than those with low scores. Pts with LU, a subtype known to be sensitive to ADT, greatly benefited from APA+ADT. Pts with BA, typically resistant to ADT, also benefited from APA+ADT. Conclusions: DECIPHER score and BA or LU subtype may be biomarkers of response to APA+ADT. DECIPHER may be useful for identifying pts for early treatment intensification with APA or other agents, and molecular subtyping may be an effective approach for pt selection in trials combining novel therapies with APA. Clinical trial information: NCT01946204. [Table: see text]

ARAMIS: Efficacy and safety of darolutamide in nonmetastatic castration-resistant prostate cancer (nmCRPC)

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Background: Delaying metastases for nmCRPC patients, while minimizing the risk of adverse events, is an important treatment goal. Darolutamide, a structurally unique androgen receptor (AR) antagonist, is being evaluated for the treatment of advanced prostate cancer. The ARAMIS trial studied the efficacy and safety of darolutamide in nmCRPC patients. Methods: This double-blind, placebo-controlled phase III trial randomized nmCRPC patients in a 2:1 ratio to receive darolutamide 600 mg (two 300 mg tablets) twice-daily or placebo, while continuing androgen deprivation therapy. Patients were stratified by prostate-specific antigen doubling time (≤6 months or >6 months) and use of osteoclast-targeted therapy. The primary endpoint was metastasis-free survival (MFS), with independent central review of radiographic imaging every 16 weeks. Secondary endpoints include overall survival (OS), times to pain progression (assessed by Brief Pain Inventory), first cytotoxic chemotherapy and first symptomatic skeletal event, as well as safety profile. Results: In total, 1,509 patients were randomized (955 to darolutamide, 554 to placebo). Median MFS was 40.4 months with darolutamide vs 18.4 months with placebo (hazard ratio [HR] 0.41; 95% confidence interval [CI] 0.34–0.50; 2-sided p<0.0001). OS showed a trend in favor of darolutamide (HR 0.71, 95% CI 0.50–0.99, 2-sided p=0.045), as did time to pain progression (HR 0.65; 95% CI 0.53–0.79; 2-sided p<0.0001). Other secondary and exploratory efficacy endpoints also favored darolutamide. Incidences of treatment-emergent adverse events (AEs) with ≥5% frequency or grade 3–5 were comparable between darolutamide and placebo arms; none except fatigue occurred in >10%. Discontinuation rates due to AEs were 8.9% with darolutamide and 8.7% with placebo. Grouped terms for AEs noted with other AR inhibitors (including fracture, falls, seizures, weight decrease, hypertension, and cognitive disorder) showed minimal or no difference in incidence between study arms. Conclusion: Among men with nmCRPC, MFS was significantly longer with darolutamide than with placebo with a low incidence of treatment-related AEs in this asymptomatic patient population. Clinical trial information: NCT02200614.

Updated analysis of progression-free survival with first subsequent therapy (PFS2) and safety in the SPARTAN study of apalutamide (APA) in patients (pts) with high-risk nonmetastatic castration-resistant prostate cancer (nmCRPC)

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Background: In the phase 3 SPARTAN study, compared with placebo (PBO), APA, a next-generation androgen receptor inhibitor, decreased the risk of distant metastasis or death by 72% (hazard ratio [HR], 0.28; p < 0.0001) in men with high-risk nmCRPC. After 1 year of additional follow-up, PFS2 and safety were reevaluated to ensure maintenance of benefit against potential harm. Methods: Pts with nmCRPC and prostate-specific antigen doubling time of ≤ 10 mos were randomized 2:1 to APA (240 mg QD) + androgen deprivation therapy (ADT) or PBO + ADT. All pts who developed distant metastasis, determined by blinded independent central review, were eligible to receive subsequent therapy including open-label treatment with abiraterone acetate + prednisone, provided by the sponsor. The exploratory PFS2 end point (time from randomization to disease progression on subsequent anticancer therapy or death) was evaluated, as was incidence of treatment-emergent adverse events (TEAEs). Results: Median treatment duration with APA was 25.7 mos; with PBO, 11.5 mos (original analysis, mos: APA, 19.2; PBO, 11.2). Pts randomized to APA continued to show significant benefit in PFS2 (HR, 0.5; 95% CI, 0.39-0.63; p < 0.0001) vs PBO (APA median time to PFS2 not reached vs PBO 39.3 mos). At a median follow-up of 32 mos, 51.3% of pts receiving APA, 8% of the 75 pts who crossed over from PBO to APA, and 99.7% of remaining PBO pts had discontinued study treatment. Rates of discontinuations due to progressive disease and AEs were 27.3% and 12.7%, respectively, in the APA group and 73.4% and 8.4% in the PBO group. There was no substantial change in the incidence of TEAEs in the APA group at the 1-year update. With regard to drug specific TEAEs, there were no grade 4 or 5 events; grade 3 TEAEs consisted of rash, 5.2%; falls, 2.4%; fractures, 3.1%; hypothyroidism, 0%; and seizures, 0%. Conclusions: APA was previously shown to result in an improvement in metastasis-free survival and symptomatic progression. With a median APA treatment duration of 25.7 mos, APA continues to show significant benefit in PFS2, and its safety profile remains unchanged. Clinical trial information: NCT01946204.

Assessment of circulating tumor cell number as a transitional surrogate endpoint for survival in phase II trials for metastatic castration-resistant prostate cancer

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Background: Short-term measures of response that reflect clinical benefit are a critical unmet need for clinical trials for mCRPC. Using data from 5 randomized mCRPC trials, we showed that a response endpoint (RE) based on a change in CTC number using the FDA cleared CellSearch® (Menarini) platform from any, (≥ 1, CTC any) to 0 (CTC0) per 7.5 ml of blood was associated strongly with overall survival (OS). Here we explored whether different CTC and PSA REs could serve as “transitional surrogates” defined as a biomarker validated in phase 2 but not in phase 3 trials for overall survival (OS), using the baseline and week 13 prostate-specific antigen (PSA) level and CTC counts. Methods: Four 13-week REs were studied: (i) PSA50 (≥ 50% PSA decline from baseline), (ii) CTC0 (≥ 1 CTC/7.5 ml of blood at baseline and 0 CTCs at week 13), (iii) both PSA50 and CTC0, and (iv) either PSA50 or CTC0. The relative effectiveness of these REs as transitional surrogates for OS was evaluated at the patient level by discrimination, the separation between responder and non-responder survival curves, and at the trial level using explained variation, the accuracy in predicting k-month survival in a trial with the response proportion. Results: A total of 6081 pts were enrolled of whom 5660 (93%) survived until week 13 and among these patients 3080 (54%) had a baseline CTC count ≥ 1 and baseline PSA ≥ 5 ng/ml. At the patient level, separation between responder and non-responder survival curves over time was greater using CTC0 than PSA50 (average difference in survival probability 0.35 vs. 0.29, respectively). At the trial level, explained variation in survival over time was also greater for CTC0 than PSA50 (average R-squared 0.67 vs. 0.58, respectively). CTC/PSA combination REs did not improve on CTC0 at either level. Conclusions: The CTC0 RE provides stronger discrimination than PSA50 at the patient level and greater observed explained variation at the trial level. The results suggest that for the individual patient, a decrease in CTCs to zero at week 13 is a stronger indicator of longer term OS than the more widely used PSA50 and serves as a reasonably likely surrogate for OS in clinical trials.

Phase II study of niraparib in patients with metastatic castration-resistant prostate cancer (mCRPC) and biallelic DNA-repair gene defects (DRD): Preliminary results of GALAHAD

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Background: New therapies are needed for patients (pts) with mCRPC progressing after androgen-receptor signaling inhibitors (ARSIs) and taxane therapies. Niraparib is a once daily highly selective inhibitor of poly (ADP-ribose) polymerase (PARP-1 and 2). Methods: GALAHAD is an ongoing open label Ph 2 study assessing niraparib (300 mg daily) in pts with DRD progressing on/after ARSIs and taxane chemotherapy. Using a validated plasma assay, DRD status was defined as pathogenic mutations (including homozygous deletions) of BRCA1/2, ATM, FANCA, PALB2, CHEK2, BRIP1 or HDAC2. Composite response rate (RR) was defined as an objective response by RECIST 1.1 for measurable disease, circulating tumor cell (CTC) conversion to < 5/7.5 mL blood or prostate-specific antigen (PSA) decline of ≥50% (PSA50). Here, preliminary data on RR and adverse events (AEs) are reported in pts with biallelic DRD. Results: As of 10 Sep 2018, 123 pts with mCRPC and DRD were enrolled, of whom 39 had biallelic DRD (23 BRCA1/2). The median follow-up was 5.7 mo (2.0–23.7). Table depicts RRs for pts with biallelic DRD by BRCA status. Composite and objective RRs were 65% and 38% in pts with biallelic BRCA1/2, respectively. 3/8 pts (38% [2/5 BRCA1/2 and 1/3 non-BRCA]) with measurable visceral metastases showed objective response. Among the 20 biallelic responders, the duration of treatment (tx) has exceeded 4 mo in 13 pts and 6 mo in 8 pts; 14 pts remain on tx. The most common grade 3/4 hematologic AEs were anemia (25%) and thrombocytopenia (15%) (manageable by dose reduction/interruption). The most common grade 3/4 nonhematologic AEs were asthenia (6%) and hypertension (5%). Conclusions: These results suggest niraparib has compelling activity as monotherapy for pts with treatment-resistant mCRPC, particularly those with biallelic BRCA1/2 identified by a blood assay. Clinical trial information: NCT02854436. [Table: see text]

Androgen receptor mutations in patients with castration-resistant prostate cancer treated with apalutamide

Background

Mutations in the androgen receptor (AR) ligand-binding domain (LBD), such as F877L and T878A, have been associated with resistance to next-generation AR-directed therapies. ARN-509-001 was a phase I/II study that evaluated apalutamide activity in castration-resistant prostate cancer (CRPC). Here, we evaluated the type and frequency of 11 relevant AR-LBD mutations in apalutamide-treated CRPC patients.

Patients and methods

Blood samples from men with nonmetastatic CRPC (nmCRPC) and metastatic CRPC (mCRPC) pre- or post-abiraterone acetate and prednisone (AAP) treatment (≥6 months' exposure) were evaluated at baseline and disease progression in trial ARN-509-001. Mutations were detected in circulating tumor DNA using a digital polymerase chain reaction-based method known as BEAMing (beads, emulsification, amplification and magnetics) (Sysmex Inostics' GmbH).

Results

Of the 97 total patients, 51 had nmCRPC, 25 had AAP-naïve mCRPC, and 21 had post-AAP mCRPC. Ninety-three were assessable for the mutation analysis at baseline and 82 of the 93 at progression. The overall frequency of detected AR mutations at baseline was 7/93 (7.5%) and at progression was 6/82 (7.3%). Three of the 82 (3.7%) mCRPC patients (2 AAP-naïve and 1 post-AAP) acquired AR F877L during apalutamide treatment. At baseline, 3 of the 93 (3.2%) post-AAP patients had detectable AR T878A, which was lost after apalutamide treatment in 1 patient who continued apalutamide treatment for 12 months.

Conclusions

The overall frequency of detected mutations at baseline (7.5%) and progression (7.3%) using the sensitive BEAMing assay was low, suggesting that, based on this assay, AR-LBD mutations such as F877L and T878A are not common contributors to de novo or acquired resistance to apalutamide.

ClinicalTrials.gov identifier

NCT01171898.