Prospective Characterization of Circulating Tumor Cells in Hormone Sensitive Oligometastatic Prostate Cancer Patients on a Metastasis-Directed Therapy Trial

PURPOSE/OBJECTIVE(S)

Prospective data have shown that metastasis-directed therapy (MDT) can alter the natural history of oligometastatic disease. In hormone-sensitive prostate cancer (HSPC), the clinical effect of MDT has been validated by STOMP, ORIOLE and SABR-COMET phase II trials. Circulating tumor cells (CTCs) are likely the source for the formation of macroscopic metastases. CTCs may provide an approach for identifying subgroups of patients with oligometastatic HSPC (oligoHSPC) that would benefit most from MDT. Our main goal was to evaluate the feasibility of CTC detection and subtypes in oligoHSPC patients that may benefit from MDT.

MATERIALS/METHODS

ORIOLE randomized men with recurrent HSPC with 1-3 metastases to observation (Obs) vs. stereotactic ablative radiotherapy (SABR) MDT. Blood samples were prospectively collected at baseline (D0) and 6-mos (D180) and shipped for analysis on Epic Sciences liquid biopsy platform (Epic Sciences, San Diego, CA). Machine learning algorithms identified CTCs and characterized androgen receptor (AR) and PSMA expression. Association with clinical factors and outcomes were examined. Biochemical failure-free survival (BFFS) event was a PSA rise of at least 2 ng/mL and 25% above nadir. Progression-free survival (PFS) was a composite endpoint including BFFS event, radiologic progression (RECIST v1.1); symptomatic progression; initiation of ADT; or death. Comparisons of patient and tumor characteristics performed by two-sample t-tests. Survival curves were generated by the Kaplan-Meier method and evaluated by the log-rank test. Effect of SABR on post-SABR on CTC levels were calculated by McNemar test.

RESULTS

A total of 82 samples were collected in ORIOLE: 70 SABR (35 D0 and 35 D180) and 12 Obs (7 D0 and 5 D180). 30/42 men had CTCs detected on D0 (71%; AR+ = 7, PSMA+ = 13) and in 26/40 on D180 (65%; AR+ = 9, PSMA+ = 8). Median follow-up was 41.7-mos. There was no association between CTC presence or subtypes (AR+ or PSMA+) with Gleason score or PSA. PFS was significantly lower in the patients with AR+ vs. AR- CTCs on D0 in the SABR arm (p = 0.011, median PFS: AR+ = 9.3- vs. AR+ = 27.1-mos). The median BFFS trended towards a difference for AR+ = 12.9- vs. AR- = 29.2-mos (D180, p = 0.058). SABR had no effect on the presence or subtypes of CTC at D180.

CONCLUSION

Baseline and dynamic CTC levels and their subtypes in oligoHSPC from the ORIOLE randomized trial of MDT was examined. AR+ CTCs at baseline and 6-mos were correlated with clinical outcomes following SABR. Longer follow-up, further analysis and a greater number of patients are needed for a more comprehensive conclusion.

End-of-radiation PSA as a novel prognostic factor in patients undergoing definitive radiation and androgen deprivation therapy for prostate cancer

Background

In men undergoing definitive radiation for prostate cancer, it is unclear whether early biochemical response can provide additional prognostic value beyond pre-treatment risk stratification.

Methods

Prostate cancer patients consecutively treated with definitive radiation at our institution by a single provider from 1993–2006 and who had an EOR PSA (n=688, median follow-up 11.2 years). We analyzed the association of an end-of-radiation (EOR) prostate-specific antigen (PSA) level, obtained during the last week of radiation, with survival outcomes. Multivariable-adjusted cox proportional hazards models were constructed to assess associations between a detectable EOR PSA (defined as ≥0.1 ng ml⁻¹) and biochemical failure-free survival (BFFS), metastasis-free survival (MFS), prostate cancer-specific survival (PCSS), and overall survival (OS). Kaplan-Meier survival curves were constructed, with stratification by EOR PSA.

Results

At the end of radiation, the PSA level was undetectable in 30% of patients. Men with a detectable EOR PSA experienced inferior 10-year BFFS (49.7% vs. 64.4%, p<0.001), 10-year MFS (84.8% vs. 92.0%, p=0.003), 10-year PCSS (94.3% vs. 98.2%, p=0.007), and 10-year OS (75.8% vs. 82.5%, p=0.01), as compared to men with an undetectable EOR PSA. Among NCCN intermediate- and high-risk men who were treated with definitive radiation and androgen deprivation therapy (ADT), a detectable EOR PSA was more strongly associated with PCSS than initial NCCN risk level (EOR PSA: HR 5.89, 95% CI 2.37–14.65, p<0.001; NCCN risk level: HR 2.01, 95% CI 0.74–5.42, p=0.168). Main study limitations are retrospective study design and associated biases.

Conclusions

EOR PSA was significantly associated with survival endpoints in men who received treated with definitive radiation and ADT. Whether the EOR PSA can be used to modulate treatment intensity merits further investigation.

Unscreened older men diagnosed with prostate cancer are at increased risk of aggressive disease

BACKGROUND

To evaluate the relationship between PSA testing history and high-risk disease among older men diagnosed with prostate cancer.

METHODS

Records from 1993 to 2014 were reviewed for men who underwent radiotherapy for prostate cancer at age 75 years or older. Patients were classified into one of four groups based on PSA-testing history: (1) no PSA testing; (2) incomplete/ineffective PSA testing; (3) PSA testing; or (4) cannot be determined. Outcomes of interest were National Comprehensive Cancer Network (NCCN) risk group (that is, low, intermediate or high risk) and biopsy grade at diagnosis. Multivariable logistic regression was used to determine the association between PSA testing history and high-risk cancer.

RESULTS

PSA-testing history was available in 274 (94.5%) of 290 subjects meeting study criteria. In total, 148 men (54.0%) underwent PSA testing with follow-up biopsy, 72 (26.3%) underwent PSA testing without appropriate follow-up, and 54 men (19.7%) did not undergo PSA testing. Patients who underwent PSA testing were significantly less likely to be diagnosed with NCCN high-risk cancer (23.0% vs 51.6%, P<0.001). On multivariable analysis, men with no/incomplete PSA testing had more than three-fold increased odds of high-risk disease at diagnosis (odds ratio 3.39, 95% confidence interval 1.96-5.87, P<0.001) as compared to the tested population.

CONCLUSIONS

Older men who underwent no PSA testing or incomplete testing were significantly more likely to be diagnosed with high-risk prostate cancer than those who were previously screened. It is reasonable to consider screening in healthy older men likely to benefit from early detection and treatment.

Solubilization of Gases by Polyethoxylated Octyl Phenols

Measurements have been made to determine the solubilities of a number of gases in aqueous solutions of commercially available polyethoxylated octyl phenols at temperatures ranging from 25&deg;C to 45&deg;C (298-318 K). The solubilities determined for each gas increase linearly with surfactant concentration. The intramicellar gas solubilities derived from these data are found to be relatively insensitive to temperature and sodium chloride in the external aqueous phase. When analyzed in terms of surfactant composition, the intramicellar gas solubilities are found to depend solely on the octyl phenol content of each surfactant. This suggests that the ethylene oxide chains of the micellized surfactant molecules do not contribute directly to the solubilization process, even under conditions near the cloud point. Copyright 1997 Academic Press. Copyright 1997Academic Press