Next-generation sequencing (NGS) of tumor tissue from >4000 men with metastatic castration-resistant prostate cancer (mCRPC): The PROfound phase III study experience

195

Background: The PROfound study (NCT02987543) showed that olaparib provides a statistically significant improvement in radiographic progression-free survival versus physician’s choice of enzalutamide or abiraterone in mCRPC patients (pts) with alterations in genes with a direct or indirect role in the homologous recombination repair (HRR) pathway. This is the largest study to date with central, prospective tumor tissue testing in pts with mCRPC. Here, we report learnings during testing in the PROfound study. Methods: An investigational clinical trial assay, based on the FoundationOne CDx NGS test developed in partnership with Foundation Medicine, Inc (FMI), was used to prospectively identify pts with qualifying alterations in ≥1 of 15 prespecified genes, including BRCA1, BRCA2 or ATM. Tumor testing was conducted centrally using archival or recent biopsy from primary or metastatic tissue. Results: Of 4047 pts who submitted tumor samples, 2792 (69%) were successfully sequenced and yielded a biomarker status. Categories for test failure (n=1255; 31%) were pathology review failure in 277 (6.8%) pts (eg estimated tumor fraction <20% or tumor volume <0.2 mm2), DNA extraction failure in 533 (13.2%) pts, and failure after DNA extraction in 280 (6.9%) pts, with 165 (4.1%) pts in >1 category. Regarding the sample disposition, approximately two-thirds of samples were from core needle biopsies, although higher success rates were observed with larger samples (ie prostatectomy). Samples were mainly from the prostate gland, with <5% from bone. Most samples were from archived tissue of primary tumors; only ~10% were from newly collected tissue. Test turnaround time, as well as representation of sample characteristics and country of origin relative to success rate, will be presented. Conclusions: The PROfound study has demonstrated that tissue testing to identify HRR alterations in men with mCRPC is feasible. Careful selection of high-quality tumor tissue samples is key to ensure success both at pathology review and during downstream steps of the NGS tissue testing process. Clinical trial information: NCT02987543.

PROPEL: A randomized, phase III trial evaluating the efficacy and safety of olaparib combined with abiraterone as first-line therapy in patients with metastatic castration-resistant prostate cancer (mCRPC)

TPS340

Background: A Phase II trial showed olaparib (tablets, 300 mg bid) in combination with abiraterone (1000 mg od plus prednisone/prednisolone 5 mg bid) significantly prolonged radiologic progression-free survival (rPFS) compared with abiraterone alone (median 13.8 vs 8.2 months; hazard ratio 0.65, 95% CI 0.44–0.97, P=0.034) in patients (pts) with mCRPC in the second-line metastatic setting who received prior docetaxel (Clarke et al. Lancet Oncol 2018). Treatment benefits were achieved irrespective of homologous recombination repair (HRR) mutation status, suggesting potential synergy between the two treatments that could impact a broader patient population. PROpel (EudraCT: 2018-002011-10) is the follow-on study to this, and the first Phase III trial to assess a PARP inhibitor in combination with abiraterone as first-line treatment in a genetically unselected mCRPC pt population. Methods: PROpel is a double-blind, placebo-controlled, international, multicenter study of pts randomized (1:1), as for the Phase II trial, to abiraterone (1000 mg od plus prednisone/prednisolone 5 mg bid) plus either olaparib (tablets, 300 mg bid) or placebo. Pts must not have received prior chemotherapy, new hormonal agents or other systemic treatment at mCRPC stage (except docetaxel at metastatic hormone-sensitive prostate cancer stage [mHSPC]). Randomization is stratified according to site of metastases (bone only vs visceral vs other) and docetaxel treatment at mHSPC stage (yes, no). The primary endpoint is investigator-assessed rPFS (RECIST v1.1 [soft tissue] and Prostate Working Cancer Group 3 [PCWG-3 criteria; bone]). Secondary objectives include time to first subsequent therapy or death, time to pain progression, overall survival, and health-related quality of life. Safety and tolerability will also be described. Exploratory endpoints include HRR subgroup analyses to confirm that efficacy is independent of HRR status. Screening across ~200 sites in 20 countries is being conducted to identify a target sample of ~720 pts. Enrollment is expected to begin in October 2018. (Study 8, NCT01972217). Clinical trial information: NCT03732820.

Health-related quality of life (HRQoL) in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with olaparib in combination with abiraterone

234

Background: A Phase II trial showed that addition of olaparib (O) to abiraterone (A) led to significant radiographic progression-free survival benefit for patients (pts) with mCRPC vs placebo (P) + A (hazard ratio [HR] 0.65, 95% confidence interval [CI] 0.44–0.97). We report predefined exploratory HRQoL analyses. Methods: This randomized, double-blind trial enrolled pts with mCRPC, post-docetaxel. Pts were randomized (71 per arm) to receive either O (300 mg bd, tablets) + A (1000 mg od) or P + A; all received prednisone (5 mg bd). Pts completed Functional Assessment of Cancer Therapy-Prostate (FACT-P total score [TS]; range 0–156, higher score = better HRQoL), Brief Pain Inventory–Short Form (BPI-SF) and worst bone pain (wbp) questionnaires (both range 0–10, higher score = more severe pain). Adjusted mean change from baseline was analysed using a mixed model for repeated measures, improvement by logistic regression and deterioration by log-rank test. Results: Overall compliance rates (O + A vs P + A) were 97% vs 96%, 92% vs 85%, and 96% vs 92% for FACT-P, BPI-SF and wbp, respectively. Best FACT-P TS response of ‘improved’ (increase ≥6 points from baseline at two consecutive visits) was reported by 22/67 (33%) evaluable pts in the O + A vs 18/64 (28%) pts in the P + A arm; the odds ratio (1.32; 95% CI 0.64–2.78) favored the O + A arm. Best FACT-P TS response of ‘worsened’ (decrease ≥6 points from baseline) was reported by 15 (22%) vs 22 (34%) pts. Adjusted mean change from baseline in FACT-P TS across all visits was -0.60 vs -2.09 in the O + A and P + A arms, respectively (difference 1.48; 95% CI -3.96–6.92). Time to deterioration (TTD) results are shown in the table. Clinical trial information: NCT01972217. Conclusions: Whilst not statistically significant, in this study a higher percentage of pts treated with O + A vs P + A had improved HRQoL, with fewer pts negatively affected. Ongoing phase III studies will help elucidate the impact of O on HRQoL in pts with mCRPC. (NCT01972217)[Table: see text]

OlympiAD: Phase III trial of olaparib monotherapy versus chemotherapy for patients (pts) with HER2-negative metastatic breast cancer (mBC) and a germline BRCA mutation (gBRCAm)

LBA4

Background: Olaparib is an oral PARP inhibitor with anti-tumor activity in HER2-negative mBC with a g BRCAm (NCT00494234). OlympiAD (NCT02000622) was a randomized, open-label, phase III study that assessed efficacy and safety of olaparib vs standard single agent chemotherapy treatment of physician’s choice (TPC) in pts with HER2-negative mBC and a g BRCAm. Methods: Pts aged ≥18 y with HER2-negative mBC (hormone receptor positive or triple negative [TN]) and a g BRCAm, who had received ≤2 chemotherapy lines for mBC, were randomized (2:1) to olaparib tablets (300 mg po bid) or TPC (21-day cycles of either capecitabine [2500 mg/m2 po days 1–14], vinorelbine [30 mg/m2 IV days 1 and 8] or eribulin [1.4 mg/m2IV days 1 and 8]). Treatment was continued until objective disease progression (RECIST v1.1) or unacceptable toxicity. The primary endpoint was progression-free survival (PFS) assessed by blinded independent central review (BICR). Results: 302 pts were randomized (median age 44 y; 50% TN; 71% prior chemotherapy for mBC; 28% prior platinum) of whom 205 received olaparib and 91 received TPC (6 TPC pts were not treated). At 77% data maturity, PFS by BICR was significantly longer in pts treated with olaparib vs TPC (HR 0.58; 95% CI 0.43, 0.80; P=0.0009; 7.0 vs 4.2 months, respectively). Time to second progression (investigator-assessed) was also longer in the olaparib arm (HR 0.57; 95% CI 0.40, 0.83). Objective response rate was 59.9 and 28.8% in olaparib and TPC arms, respectively. Grade ≥3 adverse events (AE) occurred in 36.6 and 50.5% of olaparib and TPC pts, with AEs leading to discontinuation in 4.9 and 7.7% of pts, respectively. Mean change from baseline in global health-related quality of life (HRQoL, EORTC-QLQ-C30) across all timepoints favored olaparib (difference vs TPC 7.5; 95% CI 2.48, 12.44; P=0.0035). Conclusions: Olaparib tablet monotherapy provided a statistically significant and clinically meaningful PFS benefit to HER2-negative mBC pts with a g BRCAm, compared to standard TPC. The safety profile of olaparib was consistent with prior studies. The efficacy benefit was seen beyond the first progression and HRQoL also improved. Clinical trial information: NCT02000622.

OlympiAD: Phase III trial of olaparib monotherapy versus chemotherapy for patients (pts) with HER2-negative metastatic breast cancer (mBC) and a germline BRCA mutation (gBRCAm)

LBA4

The full, final text of this abstract will be available at abstracts.asco.org at 7:30 AM (EDT) on Sunday, June 4, 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.

PROfound: A randomized Phase III trial evaluating olaparib in patients with metastatic castration-resistant prostate cancer and a deleterious homologous recombination DNA repair aberration

TPS5091

Background: The median overall survival for patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) is short. Available agents may offer limited therapeutic benefit, but no molecularly stratified treatment has yet been approved for this heterogeneous disease. A sizable percentage of pts with mCRPC has loss of function aberrations in genes involved in homologous recombination repair (HRR) in tumor tissue, such as BRCA1/2 and ATM. These aberrations can confer sensitivity to poly(ADP-ribose) polymerase (PARP) inhibition. A Phase II study indicated that the oral PARP inhibitor olaparib (Lynparza) had antitumor activity in 33% of mCRPC pts who had progressed after new hormonal agent (NHA) treatment and chemotherapy, with a strikingly higher composite response rate in pts with a deleterious HRR gene aberration (HRRa) (88%; 14/16) vs pts without a HRRa (6%; 2/33) (Mateo et al.2015). The PROfound study evaluates olaparib efficacy and safety versus physician’s choice of either abiraterone acetate or enzalutamide, in pts with mCRPC and a HRRa (NCT02987543). Methods: To be eligible for this multinational, open-label, Phase III study, mCRPC pts must have progressed on prior NHA treatment and have a tumor HRRa in one of 15 genes, as confirmed by an HRR Assay (Foundation Medicine, Inc.). Cohort A (n = 240 approx) includes pts with mutations in BRCA1, BRCA2 or ATM, while pts with a mutation in 12 other HRR genes will be assigned to Cohort B (n = 100 approx). Pts will be randomized (2:1) to olaparib tablets (300 mg orally bid) or physician’s choice of either enzalutamide (160 mg orally od) or abiraterone acetate (1000 mg orally od with 5 mg bid prednisone) and treatment continued until radiographic progression (as assessed by blinded independent central review) or lack of treatment tolerability. The primary endpoint of radiographic progression-free survival (rPFS) will be assessed in Cohort A using RECIST 1.1 (soft tissue) and PCWG3 (bone) criteria. Key secondary efficacy endpoints include confirmed objective response rate, time to pain progression, overall survival (all Cohort A) and rPFS (both cohorts combined). Clinical trial information: NCT02987543.

Effect of denosumab on prolonging bone-metastasis free survival (BMFS) in men with nonmetastatic castrate-resistant prostate cancer (CRPC) presenting with aggressive PSA kinetics

4510

Background: Denosumab, an anti-RANK-ligand monoclonal antibody, has been shown to prolong BMFS by a median 4.2 months and with a 15% risk reduction vs. placebo in men with non-metastatic CRPC and baseline PSA value ≥ 8.0 ng/mL and/or PSA doubling time (PSADT) ≤10.0 months. To determine the efficacy of denosumab in men at greatest risk for bone metastases, we evaluated BMFS in a subset of men with PSADT ≤6 months (previously reported in Smith MR, et al: J Clin Oncol. 23:2918-2925, 2005). Methods: 1,432 men with non-metastatic CRPC (baseline medians: PSA: 12.3 ng/mL, PSADT: 5.1 months, ADT duration: 47.1 months) were randomized 1:1 to receive monthly subcutaneous denosumab 120 mg or placebo. The first patient enrolled February 2006; primary analysis cut-off was July 2010, when >660 men had developed bone metastasis or died. The primary endpoint was BMFS (time to first bone metastasis or death from any cause). BMFS results are presented for men with baseline PSADT ≤6 months. Results: Median BMFS in the placebo group of men with PSADT ≤6 months was 6.5 months shorter than for the placebo group in the full population (18.7 months vs. 25.2 months), indicating that these men are at particularly high risk. In this group of men with PSADT ≤6 months, denosumab prolonged BMFS by a median of 7.2 months and with a 23% reduction in risk compared with placebo (Table). Conclusions: Patients with shortened PSADT are at higher risk of developing bone metastasis and denosumab is markedly effective at prolonging BMFS in this subset of patients. [Table: see text]

Lifetime cost-effectiveness of denosumab versus zoledronic for prevention of skeletal-related events (SREs) in patients (pts) with castrate-resistant prostate cancer (CRPC) and bone metastases (BM): United States managed care perspective

e15172

Background: Denosumab (Dmab) is superior to zoledronic acid (ZA) for prevention of SREs in pts with CRPC and BM. As Dmab is not cleared renally, it can be used in pts regardless of renal status or concomitant use of nephrotoxic drugs. Previous economic analyses were limited as the analyses were based on short duration-trial based perspectives and/or did not account for disutility associated with IV vs SC administration of ZA and Dmab, respectively. These analyses assess the lifetime cost-effectiveness of Dmab vs ZA in pts with CRPC and BM from a US managed care perspective, with extensive scenario and sensitivity analyses. Methods: A lifetime Markov model was developed, with efficacy of Dmab vs ZA in SRE prevention from a head-to-head phase 3 trial; clinical practice SRE rate in ZA pts from a large commercial claims database analysis; SRE and mode of administration (IV vs SC) quality adjusted life-year (QALY) decrements estimated using the time trade-off method; and SRE costs estimated from a nationally representative commercial claims database. Drug, drug administration, and renal monitoring costs were also included. Costs and QALYs were discounted at 3% per year. Scenario analyses (including adverse events, drug discontinuation, etc), one-way and multivariate probabilistic sensitivity analyses were conducted. Results: Dmab reduced the number of SREs and increased pts’ QALY vs ZA. In the base case and the scenario analyses, cost per QALY gained was below $50,000, which is commonly considered good value. Cost per SRE avoided was below $9,000. In one-way sensitivity analyses, drug costs and SRE rate were the most influential variables. Probabilistic sensitivity analyses showed the probabilities of Dmab being cost-effective vs ZA were 0.83, 0.94, and 0.98 with willingness-to-pay of $100,000, $150,000 and $200,000 per QALY gained, respectively. Conclusions: Dmab is a cost-effective treatment option in preventing SREs in pts with CRPC and BM compared with ZA from a US managed care perspective. The overall value of Denosumab is based on superior efficacy and more efficient administration.

Health resource utilization and patient burden associated with SREs in a randomized controlled trial setting

e19514

Background: Bone metastases (BM) are common in patients (pts) with solid tumors and may result in skeletal related events (SREs) such as spinal cord compression (SCC), pathologic fracture (PF), surgery to bone (SB), and radiation to bone (RT). SREs result in significant morbidity, debilitating pain, decreased health-related quality of life and increased health resource utilization (HRU). Data from 3 registrational phase 3 trials that showed superiority of denosumab over zoledronic acid in patients with solid tumors and BM were combined to assess HRU associated with different SRE types. Methods: Data through 41 weeks for pts with solid tumors and ≥ 1 BM enrolled in these randomized, active-controlled trials were included in this posthoc analysis. HRU were evaluated by SRE type and data were compared between pts with ≥ 1 on-study SRE and those not experiencing an on-study SRE. The index date for pts with on-study SREs was defined as the date that the first SRE was reported. The median time from randomization to incidence of first SRE for each SRE type was used to establish an index date for the control (no SRE) group. The HRU window encompassed a 3-month period (i.e.1 month before and 2 months after the index date) and was assessed by mean number of various types of medical visits during this window. Results: Data from 5,543 pts were included. PF was the most common type of first SRE (n=1,017), followed by RT (n=940), SCC (n=156), and SB (n=74). 3,618 pts did not have an on-study SRE. For all types of medical visits, HRU was higher for pts with an on-study SRE than those without (Table). Conclusions: SREs are associated with increased health resource utilization, reflecting an increased burden for patients with solid tumors and bone metastases. [Table: see text]

Baseline covariates impacting overall survival (OS) in a phase III study of men with bone metastases from castration-resistant prostate cancer

4642

Background: Prognostic models of OS in men with metastatic castrate-resistant prostate cancer (M+CRPC), have been limited. Here we present an analysis of baseline covariates associated with OS from an international phase 3 study that demonstrated superiority of denosumab over zoledronic acid for prevention of skeletal-related events (SRE) in this population (Fizazi et al., Lancet 2011;377:813-822). Methods: Patients had confirmed bone metastases (BM) from CRPC (a rising PSA despite castrate testosterone levels) and no prior bone anti-resorptive therapy. Proportional hazards modeling with various selection strategies was used to assess the prognostic significance of baseline covariates in multivariate analyses. Study-specified factors (previous SRE [Y vs N], PSA level [<10 vs ≥10 ng /mL]) and additional variables (Cook et al., Clin Cancer Res 2006;12:3361-3367; Halabi et al., J Clin Oncol 2003;21:1232-1237; Halabi et al., J Clin Oncol 2008;26:2544-2549) were explored. As no difference in OS was observed between treatment arms, analyses were performed using the pooled overall patient population. Results: Analyses included all randomized subjects with available baseline covariate data (n=1745). At the primary analysis date (median study duration 12.2 months), OS was 51%. Various selection strategies produced consistent results. In multivariate analysis, bone-specific alkaline phosphatase (BAP) ≥146 μg/L (p<0.0001) and corrected urinary N-telopeptide (uNTx) >50 nmol/mmol (p=0.0008) were associated with shorter OS, as were prior SRE (p=0.0002), PSA ≥10 ng /mL (p<0.0001), visceral metastases (p=0.0002), greater time from either diagnosis to first BM or first BM to randomization (p<0.0001 for both), ECOG performance status 2 vs. 0/1 (p=0.017), BPI-SF pain score >4 (p<0.0001), age (p=0.008), alkaline phosphatase >143 U/L (p<0.0001), and hemoglobin ≤128 g/L (p<0.0001). Conclusions: Besides known factors previously associated with OS in men with CRPC (Halabi et al., 2003), we show that bone-associated covariates (pain, prior SRE, BAP, and uNTx) are also important and independent prognostic factors for OS.

Effect of denosumab on prolonging bone-metastasis-free survival (BMFS) in men with nonmetastatic castrate-resistant prostate cancer (CRPC) presenting with aggressive PSA kinetics

6

Background: Denosumab, an anti-RANK-ligand monoclonal antibody, has been shown to prolong BMFS by a median 4.2 months and with a 15% risk reduction vs. placebo in men with non-metastatic CRPC and baseline PSA value ≥ 8.0 ng/mL and/or PSA doubling time (DT) ≤ 10.0 months. To determine the efficacy of denosumab in men at greatest risk for bone metastases, we evaluated BMFS in a subset of men with PSADT < 6 months, a cutoff based on a previous report (Smith MR, et al: J Clin Oncol. 23:2918-2925, 2005).

Methods: 1432 men with non-metastatic CRPC (baseline [median] PSA: 12.3 ng/mL, PSADT: 5.1 months, ADT duration: 47.1 months) were randomized 1:1 to receive monthly subcutaneous denosumab 120 mg or placebo. The first patient enrolled February 2006; primary analysis cut-off was July 2010, when > 660 men had developed bone metastasis or died. The primary endpoint was BMFS (time to first bone metastasis or death from any cause). BMFS results are presented for men with baseline PSADT < 6 months.

Results: Median BMFS in the placebo group of men with PSADT < 6 months was 6.5 months shorter than for the placebo group in the full population (18.7 months vs. 25.2 months), indicating that these men are at particularly high risk. In this group of men with PSADT < 6 months, denosumab prolonged BMFS by a median of 7.2 months and with a 23% reduction in risk compared with placebo (Table).

Conclusions: Patients with shortened PSADT are at higher risk of developing bone metastasis and denosumab is markedly effective at prolonging BMFS in this subset of patients.

[Table: see text]

Cost-effectiveness of denosumab (Dmab) versus zoledronic acid (ZA) for prevention of skeletal-related events (SREs) in patients (pts) with castrate-resistant prostate cancer (CRPC) and bone metastases (BM)

59

Background: It has become more important to understand the incremental cost/benefit of new medicines as healthcare costs rise. Subcutaneous Dmab is superior to intravenous ZA for prevention of SREs in pts with CRPC and BM (Fizazi, 2011). In addition, a lower proportion of pts receiving Dmab progressed to moderate/severe pain than those receiving ZA (Brown, 2011). Dmab can be used in pts regardless of renal status or concomitant use of nephrotoxic drugs. These analyses assess the lifetime, real world cost-effectiveness of Dmab vs ZA in pts with CRPC and BM from a US managed care perspective.

Methods: A lifetime Markov model was developed to estimate SREs, quality adjusted life-years (QALYs), and costs. The relative rate reduction in SREs for Dmab vs ZA was based on a large head-to-head phase 3 trial (N=1,901). The real world SRE rate in ZA pts was derived from a large commercial claims database analysis (Hatoum, 2008). SRE QALY decrements were estimated using the time trade-off method (Matza, 2011). SRE costs were estimated from a nationally representative commercial claims database (Barlev, 2010). Wholesale acquisition drug cost (Analysource, 2011), drug administration, and renal monitoring costs (National Fee Analyzer, 2011) were included. Compliance and mortality were assumed to be the same in both groups. Costs and QALYs were discounted at 3% annually.

Results: With a median pt survival of 1.7 years, Dmab reduced the number of SREs and increased pts’ QALY vs ZA. The lifetime cost/pt on Dmab was $7,430 higher than ZA. Cost/QALY gained was $65,134, commonly considered good value based on oncologists’ implied threshold in the US (Nadler, 2006). Cost/SRE avoided was $9,212.

Conclusions: Dmab is cost-effective in preventing SREs in pts with CRPC and BM compared with ZA in the US. The overall value of Dmab is based on superior efficacy and more efficient administration.

[Table: see text]