Clinical testing of transcriptome-wide expression profiles in high-risk localized and metastatic prostate cancer starting androgen deprivation therapy: an ancillary study of the STAMPEDE abiraterone Phase 3 trial

Metastatic and high-risk localized prostate cancer respond to hormone therapy but outcomes vary. Following a pre-specified statistical plan, we used Cox models adjusted for clinical variables to test associations with survival of multi-gene expression-based classifiers from 781 patients randomized to androgen deprivation with or without abiraterone in the STAMPEDE trial. Decipher score was strongly prognostic (p<2×10-5) and identified clinically-relevant differences in absolute benefit, especially for localized cancers. In metastatic disease, classifiers of proliferation, PTEN or TP53 loss and treatment-persistent cells were prognostic. In localized disease, androgen receptor activity was protective whilst interferon signaling (that strongly associated with tumor lymphocyte infiltration) was detrimental. Post-Operative Radiation-Therapy Outcomes Score was prognostic in localized but not metastatic disease (interaction p=0.0001) suggesting the impact of tumor biology on clinical outcome is context-dependent on metastatic state. Transcriptome-wide testing has clinical utility for advanced prostate cancer and identified worse outcomes for localized cancers with tumor-promoting inflammation.

Docetaxel for Nonmetastatic Prostate Cancer: Long-Term Survival Outcomes in the STAMPEDE Randomized Controlled Trial

BACKGROUND

STAMPEDE previously reported adding upfront docetaxel improved overall survival for prostate cancer patients starting long-term androgen deprivation therapy. We report long-term results for non-metastatic patients using, as primary outcome, metastatic progression-free survival (mPFS), an externally demonstrated surrogate for overall survival.

METHODS

Standard of care (SOC) was androgen deprivation therapy with or without radical prostate radiotherapy. A total of 460 SOC and 230 SOC plus docetaxel were randomly assigned 2:1. Standard survival methods and intention to treat were used. Treatment effect estimates were summarized from adjusted Cox regression models, switching to restricted mean survival time if non-proportional hazards. mPFS (new metastases, skeletal-related events, or prostate cancer death) had 70% power (α = 0.05) for a hazard ratio (HR) of 0.70. Secondary outcome measures included overall survival, failure-free survival (FFS), and progression-free survival (PFS: mPFS, locoregional progression).

RESULTS

Median follow-up was 6.5 years with 142 mPFS events on SOC (3 year and 54% increases over previous report). There was no good evidence of an advantage to SOC plus docetaxel on mPFS (HR = 0.89, 95% confidence interval [CI] = 0.66 to 1.19; P = .43); with 5-year mPFS 82% (95% CI = 78% to 87%) SOC plus docetaxel vs 77% (95% CI = 73% to 81%) SOC. Secondary outcomes showed evidence SOC plus docetaxel improved FFS (HR = 0.70, 95% CI = 0.55 to 0.88; P = .002) and PFS (nonproportional P = .03, restricted mean survival time difference = 5.8 months, 95% CI = 0.5 to 11.2; P = .03) but no good evidence of overall survival benefit (125 SOC deaths; HR = 0.88, 95% CI = 0.64 to 1.21; P = .44). There was no evidence SOC plus docetaxel increased late toxicity: post 1 year, 29% SOC and 30% SOC plus docetaxel grade 3-5 toxicity.

CONCLUSIONS

There is robust evidence that SOC plus docetaxel improved FFS and PFS (previously shown to increase quality-adjusted life-years), without excess late toxicity, which did not translate into benefit for longer-term outcomes. This may influence patient management in individual cases.

Quality of Life in Men With Prostate Cancer Randomly Allocated to Receive Docetaxel or Abiraterone in the STAMPEDE Trial

PURPOSE

Docetaxel and abiraterone acetate plus prednisone or prednisolone (AAP) both improve survival when commenced alongside standard of care (SOC) androgen deprivation therapy in locally advanced or metastatic hormone-sensitive prostate cancer. Thus, patient-reported quality of life (QOL) data may guide treatment choices.

METHODS

A group of patients within the STAMPEDE trial were contemporaneously enrolled with the possibility of being randomly allocated to receive either docetaxel + SOC or AAP + SOC. A mixed-model assessed QOL in those who had completed at least one QLQ-C30 + PR25 questionnaire. The primary outcome measure was difference in global-QOL (QLQ-C30 Q29&30) between patients allocated to docetaxel + SOC or AAP + SOC over the 2 years after random assignment, with a predefined criterion for clinically meaningful difference of > 4.0 points. Secondary outcome measures included longitudinal comparison of functional domains, pain, and fatigue, plus global-QOL at defined timepoints.

RESULTS

Five hundred fifteen patients (173 docetaxel + SOC and 342 AAP + SOC) were included. Baseline characteristics, proportion of missing data, and mean baseline global-QOL scores (docetaxel + SOC 77.8 and AAP + SOC 78.0) were similar. Over the 2 years following random assignment, the mean modeled global-QOL score was +3.9 points (95% CI, +0.5 to +7.2; P = .022) higher in patients allocated to AAP + SOC. Global-QOL was higher for patients allocated to AAP + SOC over the first year (+5.7 points, 95% CI, +3.0 to +8.5; P < .001), particularly at 12 (+7.0 points, 95% CI, +3.0 to +11.0; P = .001) and 24 weeks (+8.3 points, 95% CI, +4.0 to +12.6; P < .001).

CONCLUSION

Patient-reported QOL was superior for patients allocated to receive AAP + SOC, compared with docetaxel + SOC over a 2-year period, narrowly missing the predefined value for clinical significance. Patients receiving AAP + SOC reported clinically meaningful higher global-QOL scores throughout the first year following random assignment.

Cost-utility analysis of adding abiraterone acetate plus prednisone/prednisolone to long-term hormone therapy in newly diagnosed advanced prostate cancer in England: Lifetime decision model based on STAMPEDE trial data

Adding abiraterone acetate (AA) plus prednisolone (P) to standard of care (SOC) improves survival in newly diagnosed advanced prostate cancer (PC) patients starting hormone therapy. Our objective was to determine the value for money to the English National Health Service (NHS) of adding AAP to SOC. We used a decision analytic model to evaluate cost-effectiveness of providing AAP in the English NHS. Between 2011-2014, the STAMPEDE trial recruited 1917 men with high-risk localised, locally advanced, recurrent or metastatic PC starting first-line androgen-deprivation therapy (ADT), and they were randomised to receive SOC plus AAP, or SOC alone. Lifetime costs and quality-adjusted life-years (QALYs) were estimated using STAMPEDE trial data supplemented with literature data where necessary, adjusting for baseline patient and disease characteristics. British National Formulary (BNF) prices (£98/day) were applied for AAP. Costs and outcomes were discounted at 3.5%/year. AAP was not cost-effective. The incremental cost-effectiveness ratio (ICER) was £149,748/QALY gained in the non-metastatic (M0) subgroup, with 2.4% probability of being cost-effective at NICE's £30,000/QALY threshold; and the metastatic (M1) subgroup had an ICER of £47,503/QALY gained, with 12.0% probability of being cost-effective. Scenario analysis suggested AAP could be cost-effective in M1 patients if priced below £62/day, or below £28/day in the M0 subgroup. AAP could dominate SOC in the M0 subgroup with price below £11/day. AAP is effective for non-metastatic and metastatic disease but is not cost-effective when using the BNF price. AAP currently only has UK approval for use in a subset of M1 patients. The actual price currently paid by the English NHS for abiraterone acetate is unknown. Broadening AAP's indication and having a daily cost below the thresholds described above is recommended, given AAP improves survival in both subgroups and its cost-saving potential in M0 subgroup.

Addition of abiraterone to first-line long-term hormone therapy in prostate cancer (STAMPEDE): Model to estimate long-term survival, quality-adjusted survival, and cost-effectiveness

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Background: Results from randomised trials show adding abiraterone acetate plus prednisolone (AAP) to standard of care (SOC) improves disease-free and overall survival in men with prostate cancer (PC) starting long-term hormone therapy for first time. Formal assessment is required of whether funding AAP here shows appropriate use of resources. This cost-effectiveness decision model tests if giving AAP to these patients is cost-effective using costs from English National Health Service, the largest nation where STAMPEDE recruited. Methods: Health outcomes and costs were modelled using patient data from AAP comparison of STAMPEDE (recruitment 2011-14). This included 1917 men with high-risk, locally advanced metastatic or recurrent PC starting 1st-line hormone therapy. SOC was hormone therapy for ≥2 years with radiotherapy in pre-selected patients. If allocated to research group, AAP (AA 1000mg/day, P 5mg/day) was added to SOC. The model makes lifetime predictions of survival, costs and quality-adjusted lifeyears (QALYs), with costs and QALYs discounted at 3.5% annually. Sensitivity analyses were performed. Results: The model predicted AAP would extend survival (discounted quality-adjusted survival) by 2.68y (1.46 QALYs) for metastatic patients and 0.30y (0.29 QALYs) for non-metastatic. The cost of AAP means it is not currently cost-effective in this setting, including with Patient Access Scheme costs for AAP and enzalutamide and similar reductions for cabazitaxel and Ra. If AAP’s price reduces after patent expiry as expected (90% reduction on BNF cost), it would be cost-effective in both patient groups, with incremental cost-effectiveness ratios below £10,000 (US$12,665) per QALY. AAP could also dominate in non-metastatic patients (i.e. lower costs and higher QALYs than SOC alone). Conclusions: AAP could be cost-effective for patients with non-metastatic and metastatic disease with expected future pricing and may be cost-saving in the former. Policymakers should encourage license submissions and generic price reductions to facilitate use of AAP given cost-saving potential in addition to improving survival. Clinical trial information: NCT00268476.

Comparative quality of life in patients randomized contemporaneously to docetaxel or abiraterone in the STAMPEDE trial

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Background: Docetaxel (DOC) and abiraterone (ABI) both improve overall survival (OS) in men with locally advanced or metastatic hormone-sensitive prostate cancer (HSPC) but no head to head trials compare the 2 agents. STAMPEDE, a multi-arm multi-stage platform trial, recruited patients (pts) to treatments including DOC or ABI between Nov-11 and Mar-13. There was no evidence OS differed between DOC or ABI, thus quality of life (QOL) may increasingly inform treatment options. Methods: QOL scores were analysed in pts contemporaneously randomised to receive DOC or ABI, in addition to standard of care treatment. Self-assessment QOL questionnaires EORTC QLQ C30 and PR25 were completed during treatment and follow-up. These analyses focus on average global QOL over the first 2 years after randomisation, using repeated measures analysis, plus cross-sectional analyses at 3, 6, 12 and 24 months. A score difference of ≥4 points was pre-defined as clinically meaningful. Results: 173 men randomised to DOC and 342 men randomised to ABI participated in the QOL sub-study and contributed to this analysis. Baseline characteristics and proportion of missing data were similar between groups. Baseline global QOL scores were similar (mean (sd): DOC 77.8 (20) and ABI 78.0 (19.3)). Average global QOL over 2 years was higher in pts randomised to ABI than DOC, although the difference was statistically significant it did not meet the pre-defined clinical parameter (+3.9, 95%CI 0.6 to 7.1, p=0.021). Cross-sectional analyses showed clinically meaningful superior QOL in the ABI group at 3 and 6 months (+6.6, 95%CI 2.6 to 10.7, p=0.001; +8.0, 95%CI 3.6 to 12.3, p<0.001), but not at 1 or 2 years (+1.3, 95%CI -3.0 to 5.6, p=0.545; +4.5, 95%CI -0.25 to 9.2, p=0.063). An exploratory analysis indicated average QOL for pts with metastatic disease (n=207) was better in the ABI group (+4.44, 95%CI 0.2 to 8.6, p=0.036). Conclusion: Global QOL was significantly higher in the first 2 years of treatment for the ABI group compared to the DOC group, though did not meet the pre-defined clinically meaningful threshold. The majority of difference was seen in the first year of treatment. This should be considered when discussing treatment options with pts. Clinical trial information: NCT00268476.