Anuradha Jayaram

Plasma AR and abiraterone-resistant prostate cancer

Androgen receptor mutations and amplifications in circulating tumor DNA provide clues to prostate cancer drug resistance. Detecting resistance before it starts Androgen receptor targeting is the cornerstone of prostate cancer treatment. Even when the tumors become “castration-resistant” or no longer sensitive to androgen deprivation, androgen signaling can still be effectively targeted by newer drugs such as abiraterone and enzalutamide, which also inhibit the androgen signaling axis. Romanel et al. analyzed tumor DNA samples from the blood of 97 patients with castration-resistant prostate cancer at different times during the course of treatment with abiraterone. Although some new mutations emerged during therapy, the authors found that androgen receptor amplifications were present from the beginning and correlated with abiraterone resistance, suggesting that detection of these amplifications should be useful for identifying abiraterone-resistant cancers before starting treatment. Androgen receptor (AR) gene aberrations are rare in prostate cancer before primary hormone treatment but emerge with castration resistance. To determine AR gene status using a minimally invasive assay that could have broad clinical utility, we developed a targeted next-generation sequencing approach amenable to plasma DNA, covering all AR coding bases and genomic regions that are highly informative in prostate cancer. We sequenced 274 plasma samples from 97 castration-resistant prostate cancer patients treated with abiraterone at two institutions. We controlled for normal DNA in patients’ circulation and detected a sufficiently high tumor DNA fraction to quantify AR copy number state in 217 samples (80 patients). Detection of AR copy number gain and point mutations in plasma were inversely correlated, supported further by the enrichment of nonsynonymous versus synonymous mutations in AR copy number normal as opposed to AR gain samples. Whereas AR copy number was unchanged from before treatment to progression and no mutant AR alleles showed signal for acquired gain, we observed emergence of T878A or L702H AR amino acid changes in 13% of tumors at progression on abiraterone. Patients with AR gain or T878A or L702H before abiraterone (45%) were 4.9 and 7.8 times less likely to have a ≥50 or ≥90% decline in prostate-specific antigen (PSA), respectively, and had a significantly worse overall [hazard ratio (HR), 7.33; 95% confidence interval (CI), 3.51 to 15.34; P = 1.3 × 10−9) and progression-free (HR, 3.73; 95% CI, 2.17 to 6.41; P = 5.6 × 10−7) survival. Evaluation of plasma AR by next-generation sequencing could identify cancers with primary resistance to abiraterone.

Androgen receptor gene status in plasma DNA associates with worse outcome on enzalutamide or abiraterone for castration-resistant prostate cancer: a multi-institution correlative biomarker study.

Abstract Background There is an urgent need to identify biomarkers to guide personalized therapy in castration-resistant prostate cancer (CRPC). We aimed to clinically qualify androgen receptor (AR) gene status measurement in plasma DNA using multiplex droplet digital PCR (ddPCR) in pre- and post-chemotherapy CRPC. Methods We optimized ddPCR assays for AR copy number and mutations and retrospectively analyzed plasma DNA from patients recruited to one of the three biomarker protocols with prospectively collected clinical data. We evaluated associations between plasma AR and overall survival (OS) and progression-free survival (PFS) in 73 chemotherapy-naïve and 98 post-docetaxel CRPC patients treated with enzalutamide or abiraterone (Primary cohort) and 94 chemotherapy-naïve patients treated with enzalutamide (Secondary cohort; PREMIERE trial). Results In the primary cohort, AR gain was observed in 10 (14%) chemotherapy-naïve and 33 (34%) post-docetaxel patients and associated with worse OS [hazard ratio (HR), 3.98; 95% CI 1.74–9.10; P < 0.001 and HR 3.81; 95% CI 2.28–6.37; P < 0.001, respectively], PFS (HR 2.18; 95% CI 1.08–4.39; P = 0.03, and HR 1.95; 95% CI 1.23–3.11; P = 0.01, respectively) and rate of PSA decline ≥50% [odds ratio (OR), 4.7; 95% CI 1.17–19.17; P = 0.035 and OR, 5.0; 95% CI 1.70–14.91; P = 0.003, respectively]. AR mutations [2105T>A (p.L702H) and 2632A>G (p.T878A)] were observed in eight (11%) post-docetaxel but no chemotherapy-naïve abiraterone-treated patients and were also associated with worse OS (HR 3.26; 95% CI 1.47–not reached; P = 0.004). There was no interaction between AR and docetaxel status (P = 0.83 for OS, P = 0.99 for PFS). In the PREMIERE trial, 11 patients (12%) with AR gain had worse PSA-PFS (sPFS) (HR 4.33; 95% CI 1.94–9.68; P < 0.001), radiographic-PFS (rPFS) (HR 8.06; 95% CI 3.26–19.93; P < 0.001) and OS (HR 11.08; 95% CI 2.16–56.95; P = 0.004). Plasma AR was an independent predictor of outcome on multivariable analyses in both cohorts. Conclusion Plasma AR status assessment using ddPCR identifies CRPC with worse outcome to enzalutamide or abiraterone. Prospective evaluation of treatment decisions based on plasma AR is now required. Clinical Trial number NCT02288936 (PREMIERE trial).

Prostate-specific Antigen Decline After 4 Weeks of Treatment with Abiraterone Acetate and Overall Survival in Patients with Metastatic Castration-resistant Prostate Cancer.

BACKGROUND The availability of multiple new treatments for metastatic castration-resistant prostate cancer (mCRPC) mandates earlier treatment switches in the absence of a response. A decline in prostate-specific antigen (PSA) is widely used to monitor treatment response, but is not validated as an intermediate endpoint for overall survival (OS). OBJECTIVE To evaluate the association between early PSA decline and OS following abiraterone acetate (AA) treatment. DESIGN, SETTING, AND PARTICIPANTS We identified mCRPC patients treated with AA before or after docetaxel at the Royal Marsden NHS Foundation Trust between 2006 and 2014. Early PSA decline was defined as a 30% decrease in PSA at 4 wk relative to baseline, and early PSA rise as a 25% increase. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Association with OS was analyzed using multivariate Cox regression and log-rank analyses. Spearmans rho correlation coefficient (r) was calculated to evaluate the association between PSA changes at 4 wk and 12 wk. RESULTS AND LIMITATIONS There were 274 patients eligible for this analysis. A 30% PSA decline at 4 wk was associated with longer OS (25.8 vs 15.1 mo; hazard ratio [HR] 0.47, p<0.001), and a 25% PSA rise at 4 wk with shorter OS (15.1 vs 23.8 mo; HR 1.7, p=0.001) in both univariate and multivariable models. The percentage PSA decline at 4 wk was significantly correlated with the percentage PSA change at 12 wk (r=0.82; p<0.001). Patients achieving a 30% PSA decline at 4 wk were 11.7 times more likely to achieve a 50% PSA decrease at 12 wk (sensitivity 90.9%, specificity 79.4%). Limitations include the retrospective design of this analysis. CONCLUSIONS Patients not achieving 30% PSA decline after 4 wk of AA have a lower likelihood of achieving PSA response at 12 wk and significantly inferior OS. Prospective multicentre validation studies are needed to confirm these findings. PATIENT SUMMARY Prostate-specific antigen (PSA) is commonly used to evaluate response to treatment in metastatic castration-resistant prostate cancer. Expert recommendations discourage reliance on PSA changes earlier than 12 wk after treatment initiation. Our data suggest that early PSA changes are associated with survival in patients receiving abiraterone acetate.

Prostate cancer: Cabazitaxel-a key therapeutic option in prostate cancer.

Treatment with cabazitaxel is associated with improved survival in patients with metastatic castration-resistant prostate cancer. Bahl et al. recently reported that patient-reported quality-of-life metrics were stable—with a trend towards improvements with increasing numbers of treatment cycles—in 112 patients treated with cabazitaxel in the UK.

Phase II pilot study of the prednisone to dexamethasone switch in metastatic castration-resistant prostate cancer (mCRPC) patients with limited progression on abiraterone plus prednisone (SWITCH study)

BackgroundDespite most metastatic castration-resistant prostate cancer (mCRPC) patients benefit from abiraterone acetate plus prednisone 5 mg bid (AA + P), resistance eventually occurs. Long-term use of prednisone has been suggested as one of the mechanisms driving resistance, which may be reversed by switching to another steroid.MethodsSWITCH was a single-arm, open-label, single-stage phase II study. The primary objective was to evaluate the antitumour activity of abiraterone acetate plus dexamethasone 0.5 mg daily (AA + D) in mCRPC patients progressing to AA + P. Clinically stable mCRPC patients who had prostate-specific antigen (PSA) and/or limited radiographic progression after at least 12 weeks on AA + P, were eligible. The primary endpoint was measured as the proportion of patients achieving a PSA decline of  ≥ 30% (PSA30) from baseline after 6 weeks on AA + D. Secondary endpoints included: PSA50 response rate at 12 weeks, time to biochemical and radiological progression, overall survival, safety profile evaluation, benefit from subsequent treatment lines and the identification of biomarkers of response (AR copy number, TMPRSS2-ERG status and PTEN expression).ResultsTwenty-six patients were enrolled. PSA30 and PSA50 were 46.2% and 34.6%, respectively. Median time to biochemical and radiological progression were 5.3 and 11.8 months, respectively. Two radiological responses were observed. Median overall survival was 20.9 months. Patients with AR gain detected in plasma circulating tumour DNA did not respond to switch, whereas patients with AR normal status benefited the most. No significant toxicities were observed and PSA50 response rate to subsequent taxane was 50%.ConclusionsIn selected clinical stable mCRPC patients with limited disease progression on AA + P, a steroid switch from prednisone to dexamethasone can lead to PSA and radiological responses.

Managing Metastatic Castration-Resistant Prostate Cancer in the Pre-chemotherapy Setting: A Changing Approach in the Era of New Targeted Agents.

In recent years, the therapeutic options for treating men with metastatic castration-resistant prostate cancer have increased substantially. The hormonal treatments abiraterone acetate and enzalutamide, the chemotherapeutics docetaxel and cabazitaxel, the radiopharmaceutical alpharadin and the immunotherapeutic Sipuleucel-T have entered the field. Additionally, corticosteroids, which are used extensively, have documented activity but no documented survival benefit. Physicians treating patients with metastatic prostate cancer immediately after castration resistance develops currently have at least four different options to choose from for the first treatment. These therapeutic choices and their several possible ways of sequential use have not yet been compared to each other head-to-head and may never be. Therefore, there is an unmet need to inform their use with prospective clinical data. Additionally, the new indications of docetaxel for hormone naïve prostate cancer is changing the landscape of prostate cancer treatment and questions the traditional classifications ‘pre-chemotherapy’ and ‘post-chemotherapy’. In this work we attempt to address these challenges in the treatment of metastatic castration-resistant prostate cancer with the focus mainly on the non-cytotoxic agents. We try to integrate available clinical and preclinical information to suggest optimal ways of treatment.

Does interval from histologic diagnosis (Dx) to start of chemotherapy (Ctx) impact survival in metastatic colorectal cancer (MCRC)

615 Background: Optimal timing from colorectal surgery to initiation of adjuvant chemotherapy is between 4 to 6 weeks based on recent data. In MCRC, therapeutic benefits of ctx are frequently calculated from start of treatment. We investigated whether the interval between dx and commencement of ctx influences overall survival (OS) in patients (pts) with MCRC. Methods: Pts with CRC were identified from the institutional database. Inclusion criteria were MCRC and receipt of ctx. Clinicopathologic details were collected. Intervals from histologic dx to ctx were calculated. Analyses were based on receipt of ctx within 4 weeks (w), 5-8w and > 8w of dx. Survival was compared between groups. OS was presented as hazard ratio (HR) with associated p value. Results: Between 2003 and 2013, 123 pts were identified, where 58 pts receive ctx within 4w, 38 within 5-8w and 27 > 8w. Median OS (mOS) was 8.7, 15.7 and 13.7 months (mths) respectively. Improvement in OS was noted in pts treated 5-8w and >8w compared to within ...

Response to second-line chemotherapy (Ctx) in advanced urothelial carcinoma: A pooled retrospective analysis of the correlation between objective response rate (ORR) and progression-free survival (PFS) and overall survival (OS).

354 Background: Second-line ctx for advanced urothelial carcinoma (UC) constitutes a substantial unmet need. A commonly used endpoint in phase II studies is ORR, however it is unclear whether this translates to a benefit in OS and PFS. We previously examined pooled OS, PFS, ORR and DCR in second line ctx in advance UC. We now are now determining whether increased ORR correlates with improved PFS and OS. Methods: Published second-line studies were identified from PubMed between 1997- 2012 and were reviewed for data extraction. Pearson correlation coefficient was used to determine correlation between ORR and OS and PFS. Results: 25 prospective studies of second-line ctx for progressive advanced UC were identified (22 non-randomised, 3 randomised) (n= 1,297). The majority of studies (88%) were phase II. 12 studies investigated combination regimens and 13 studies monotherapy. All studies allowed adjuvant and primary chemotherapy as first-line but only 7 studies reported median time from last chemotherapy. The...

Influence of ABO blood group on the natural history of advanced pancreatic adenocarcinoma (PC).

307 Background: An association between blood group (ABO) and PC has been demonstrated at epidemiologic and genomic levels. Variations in ABO type may lead to higher pro-inflammatory cytokines levels with modifications in cellular adhesionand signalling promoting carcinogenesis. This study investigated the influence of ABO on the clinical behaviour of advanced PC in patients (pts) , treated with chemotherapy (ctx). Methods: Pts with confirmed PC were identified from 4 institutional databases. Inclusion criteria were unresectable (UPC) or metastatic disease (MPC), receipt of ctx and availability of ABO data. Clinicopathologic details were collected. 200 random anonymied non-cancer ABO samples were collected as control. Descriptive statistics and survival analyses were performed. Results: Between 2001 and 2012, 222 pts met inclusion criteria. Median age was 63 years (range: 33 – 83) 56% were males. 60% of pts had MPC and 27% received doublet ctx. ABO distribution was: A (40%), AB (5%), B (11%) and O (44%). T...