Current and Emerging Therapies for Metastatic Castration-Resistant Prostate Cancer (mCRPC).

Metastatic castration-resistant prostate cancer (mCRPC) encompasses a heterogeneous wide range of molecular tumor behavior and a high risk of progression. Early detection and treatment are therefore crucial in these patients. Treatment has improved drastically in recent years and many novel therapeutic agents are currently under investigation. However, due to the rapidly changing therapeutic landscape in mCRPC, it is difficult for clinicians to keep up to date with the latest innovations in this area. In the present narrative review, we discuss the current and emerging therapies for mCRPC as well as the clinical and molecular factors that can help predict which patients are most likely to benefit from these novel agents.

Nonmetastatic castration-resistant prostate cancer: Novel agents to treat a lethal disease.

Nonmetastatic castration-resistant prostate cancer (nmCRPC) - defined as prostate-specific antigen (PSA) > 2 ng/mL, testosterone castration levels < 1.7 nm/L, and the absence of metastatic lesions on conventional imaging (computed tomography or bone scan) - has been defined as a lethal disease by the Prostate Cancer Work Group. One-third of patients with prostate cancer who receive androgen deprivation therapy for biochemical recurrence after local treatment will develop CRPC, with death occurring an average of 2.5 years after diagnosis of castration resistance. Most patients diagnosed with nmCRPC are asymptomatic or minimally symptomatic at diagnosis due to local treatment. In patients with short PSA doubling times (< 10 mo) and high baseline PSA levels, there is a high risk of bone metastases followed by prostate cancer-related mortality. These patients also present significant morbidity that negatively impacts quality of life (QoL). Recently, the results of three randomized trials (PROSPER, SPARTAN, and ARAMIS) were published. Those trials evaluated the efficacy of three different androgen receptor inhibitors - enzalutamide, apalutamide, and darolutamide - in patients with nmCRPC. In all three trials, the study drugs improved both metastasis-free survival and overall survival compared to placebo, plus on-going androgen deprivation therapy without a negative impact on QoL. In patients with nmCRPC, the most important clinical objective is early detection and treatment to maintain a low tumor burden and to prolong the symptom-free interval. For patients with nmCRPC, these novel drugs offer new hope for better QoL and survival outcomes.

Prognostic correlation of cell cycle progression score and Ki-67 as a predictor of aggressiveness, biochemical failure, and mortality in men with high-risk prostate cancer treated with external beam radiation therapy.

OBJECTIVES: Ki-67 is a proliferation marker in prostate cancer. A prognostic RNA signature was developed to characterize prostate cancer aggressiveness. The aim was to evaluate prognostic correlation of CCP and Ki-67 with biochemical failure (BF), and survival in high-risk prostate cancer patients (pts) treated with radiation therapy (RT). METHODS: CCP score and Ki-67 were derived retrospectively from pre-treatment paraffin-embedded prostate cancer tissue of 33 men diagnosed from 2002 to 2006. CCP score was calculated as an average expression of 31 CCP genes. Ki-67 was determined by IHC. Single pathologist evaluated all tissues. Factors associated to failure and survival were analyzed. RESULTS: Median CCP score was 0.9 (-0-1 - 2.6). CCP 0: 1 pt; CCP 1: 19 pts; CCP 2: 13 pts. Median Ki-67 was 8.9. Ki-67 cutpoint was 15.08%. BF and DSM were observed in 21% and 9%. Ki-67 ≥ 15% predicted BF (p = 0.043). With a median follow-up of 8.4 years, 10-year BF, OS, DM and DSM for CCP 1 vs. CCP 2 was 76-71% (p = 0.83), 83-73% (p = 0.86), 89-85% (p = 0.84), and 94-78% (p = 0.66). On univariate, high Ki-67 was correlated with BF (p = 0.013), OS (p = 0.023), DM (p = 0.007), and DSM (p = 0.01). On Cox MVA, high Ki-67 had a BF trend (p = 0.063). High CCP score was not correlated with DSM. CONCLUSIONS: High Ki-67 significantly predicted outcome and provided prognostic information. CCP score may improve accuracy stratification. We did not provide prognostic correlation of CCP and DSM. It should be validated in a larger cohort of pts.

Salvage brachytherapy in prostate local recurrence after radiation therapy: predicting factors for control and toxicity.

PURPOSE: To evaluate efficacy and toxicity after salvage brachytherapy (BT) in prostate local recurrence after radiation therapy. METHODS AND MATERIALS: Between 1993 and 2007, we retrospectively analyzed 56 consecutively patients (pts) undergoing salvage brachytherapy. After local biopsy-proven recurrence, pts received 145 Gy LDR-BT (37 pts, 66%) or HDR-BT (19 pts, 34%) in different dose levels according to biological equivalent doses (BED(2 Gy)). By the time of salvage BT, only 15 pts (27%) received ADT. Univariate and multivariate analyses were performed to identify predictors of biochemical control and toxicities. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicities were graded using Common Terminology Criteria for Adverse Events (CTCv3.0). RESULTS: Median follow-up after salvage BT was 48 months. The 5-year FFbF was 77%. HDR and LDR late grade 3 GU toxicities were observed in 21% and 24%. Late grade 3 GI toxicities were observed in 2% (HDR) and 2.7% (LDR). On univariate analysis, pre-salvage prostate-specific antigen (PSA) > 10 ng/ml (p = 0.004), interval to relapse after initial treatment < 24 months (p = 0.004) and salvage HDR-BT doses BED(2 Gy) level < 227 Gy (p = 0.012) were significant in predicting biochemical failure. On Cox multivariate analysis, pre-salvage PSA, and time to relapse were significant in predicting biochemical failure. HDR-BT BED(2 Gy) (α/ß 1.5 Gy) levels ≥ 227 (p = 0.013), and ADT (p = 0.049) were significant in predicting grade ≥ 2 urinary toxicity. CONCLUSIONS: Prostate BT is an effective salvage modality in some selected prostate local recurrence patients after radiation therapy. Even, we provide some potential predictors of biochemical control and toxicity for prostate salvage BT, further investigation is recommended.

Clinical effects in a cohort of cancer patients overexposed during external beam pelvic radiotherapy.

PURPOSE: To evaluate the clinical outcome of 28 overexposed cancer patients in a cohort of 153 treated with pelvic irradiation and to correlate the outcome with the doses received. METHODS AND MATERIALS: Between August 2000 and March 2001, 153 patients were treated at the Instituto Oncológico Nacional of Panama with radiotherapy for cancers of the cervix, uterus, endometrium, prostate, and rectum using conventional techniques. In 56 patients, irradiated with partially blocked teletherapy fields, the treatment times were determined using a treatment planning system that generated isodose distributions. The absorbed doses received by the patients were calculated and the biologically effective doses (BEDs) and 2-Gy equivalent doses derived. The clinical outcome was evaluated using the Radiation Therapy Oncology Group (RTOG) and late effects on normal tissues-subjective, objective, management, analytic scales (LENT/SOMA). The relationships between clinical outcome and dose were investigated and compared with published data. RESULTS: Of the 56 patients for whom treatment times were generated with the treatment planning system, 28 received some doses per fraction approximately double those prescribed. Using an alpha/beta = 10 Gy, the tumor BED(10) values ranged from 77 to 225 Gy. The rest of the patients received doses within 10% of the prescribed values. Seventeen of the 28 overexposed patients died 35 days to 21 months after treatment; 13 of the fatalities were caused by rectal complications. Survival was longer in those patients who had undergone colostomy. Bladder complications were less enhanced. The nonoverexposed patients with cervical cancer exhibited a greater incidence of treatment failures than generally reported in other centers. CONCLUSION: This study provides the clinical outcome after high doses of pelvic radiotherapy in a range not previously well documented. For cervical cancer patients receiving both tele- and brachytherapy, some deaths in this overexposure cohort occurred from assumed consequential rectal injury within 2 years, when the BED(10) values exceeded 70-80 Gy. The incidence was asymptotic to 100% fatalities at >150 Gy. This confirmed and extended other data in the literature.