Radiotherapy to the Primary Tumor: The First Step of a Tailored Therapy in Metastatic Prostate Cancer

Beyond the status quo: when disease volume and metastatic timing are not enough to personalize treatment in mHSPC

This review explores the complexities of treatment intensification in metastatic hormone-sensitive prostate cancer (mHSPC), emphasizing the limitations of using disease volume and metastatic timing as sole prognostic factors. Current algorithms focus on clinical factors like ECOG, comorbidities, and patient preferences, yet lack biomarkers for more individualized therapy. By examining prognostic indicators - clinical, analytical, pathological, molecular, and imaging - this article highlights the importance of a personalized approach. Multimodal strategies and predictive biomarkers are proposed to optimize therapy selection between doublet and triplet regimens, ultimately improving patient outcomes. Future trials incorporating emerging biomarkers may provide the basis for precision treatment in mHSPC, shifting management beyond conventional classifications.

Treatment intensification in metastatic castration-sensitive prostate cancer: a real-world study in Alberta, Canada

AIM

To assess the current status of and factors associated with treatment intensification (TI) (with androgen receptor pathway inhibitors [ARPIs] and/or docetaxel) for metastatic castration-sensitive prostate cancer (mCSPC) in Canada.

MATERIALS & METHODS

Retrospective analysis of data for 431 patients with mCSPC from the Alberta Prostate Cancer Research Initiative database (July 2014-March 2022). The primary objective was to assess the patient proportion receiving TI, time to TI, and associated factors. The secondary and exploratory objectives were evaluating TI patterns and factors associated with choice of therapy, respectively.

RESULTS

Overall, 42% of patients received TI; most (65%) within 3 months post-index. TI was likely to occur within 3 months post-index in de novo mCSPC, but occurred later for recurrent mCSPC. Patients with recurrent mCSPC (HR [95% CI]: 0.52 [0.38-0.72]) and those aged ≥ 75 years (0.57 [0.36-0.93]) were less likely to receive TI. Patients with multiple metastatic sites and bone metastasis had a 2-3-fold higher likelihood of receiving TI. An ARPI was predominantly used (75%) for TI (median duration: 16.0 months).

CONCLUSION

TI rates for mCSPC are suboptimal in Canada especially for older patients and those with recurrent mCSPC. TI prioritization in such groups may improve patient outcomes.

Real-World Treatment Patterns and Survival Outcomes in Metastatic Hormone-Sensitive Prostate Cancer: Insights From a Retrospective Cohort Study

BACKGROUND

Real-world data on treatment patterns and survival outcomes in metastatic hormone-sensitive prostate cancer (mHSPC) remain limited. This study aims to characterize treatment sequencing, duration across lines of therapy, and survival outcomes in patients with mHSPC.

METHODS

This single-center, retrospective, non-interventional study included men newly diagnosed with mHSPC at King Abdullah Medical City Cancer Center between 2016 and 2023. Treatment patterns, including sequencing and duration of therapy, were described. Kaplan-Meier methods were used to estimate overall survival (OS) from mHSPC diagnosis to death or censoring at the end of follow-up.

RESULTS

Among 102 patients, the mean age was 70 years, BMI of 26, with 53% having a performance status of 2. Comorbidities included hypertension (51%), diabetes (45%), and cardiovascular disease (20.6%). Nearly half (48%) had a Gleason score of nine, with 62.7% presenting with bone metastases. Novel hormonal therapy (NHT) was the predominant first-line treatment (86%), with abiraterone used in 43% of cases. Second- and third-line treatments were received by 34% and 13% of patients, respectively. The median durations of first-, second-, and third-line therapies were 21, 5, and 2.6 months, respectively. Median OS from diagnosis was 24 months.

CONCLUSION

Despite the predominant use of novel hormonal therapy (NHT), patients in this cohort exhibited aggressive disease and poor survival outcomes. These findings highlight a critical need for more intensive and tailored treatment strategies for mHSPC.

An MRI radiomics model for predicting a prostate-specific antigen response following abiraterone treatment in patients with metastatic castration-resistant prostate cancer

Objective

To establish a combined radiomics-clinical model for the early prediction of a prostate-specific antigen(PSA) response in patients with metastatic castration-resistant prostate cancer(mCRPC) after treatment with abiraterone acetate(AA).

Methods

The data of a total of 60 mCRPC patients from two hospitals were retrospectively analyzed and randomized into a training group(n=48) or a validation group(n=12). By extracting features from biparametric MRI, including T2-weighted imaging(T2WI), diffusion-weighted imaging(DWI), and apparent diffusion coefficient(ADC) maps, radiomics features from the training dataset were selected using least absolute shrinkage and selection operator(LASSO) regression. Four predictive models were developed to assess the efficacy of abiraterone in treating patients with mCRPC. The primary outcome variable was the PSA response following AA treatment. The performance of each model was evaluated using the area under the receiver operating characteristic curve(AUC). Univariate and multivariate analyses were performed using Cox regression to identify significant predictors of the efficacy of abiraterone treatment in patients with mCRPC.

Results

The integrated model was constructed from seven radiomics features extracted from the T2WI, DWI, and ADC sequence images of the training data. This model demonstrated the highest AUC in both the training and validation cohorts, with values of 0.889 (95% CI, 0.764-0.961) and 0.875 (95% CI, 0.564-0.991). The Rad-score served as an independent predictor of the response to abiraterone treatment in patients with mCRPC (HR: 2.21, 95% CI: 1.01-4.44).

Conclusion

The biparametric MRI-based radiomics model has the potential to predict the PSA response in patients with mCRPC following abiraterone treatment.

Clinical relevance statement

The MRI-based radiomics model could be used to noninvasively identify the AA response in mCRPC patients, which is helpful for early clinical decision-making.

Natural Compounds and Histone Deacetylase Inhibitors: A Combined Approach Against mCRPC Cells

Background: Sodium butyrate (NaBu), a short-chain fatty acid, modulates global gene expression through histone deacetylase (HDAC) inhibition, suppressing proliferation and inducing apoptosis in various cancers. Rutin (RUT), a polyphenolic flavonoid found in many plants, exhibits notable anticancer properties. Combining chemotherapeutic agents with natural polyphenols represents a promising strategy for cancer therapy. This study aims to evaluate, for the first time, the potential effects of NaBu and RUT combination therapy on metastatic castration-resistant prostate cancer (mCRPC) cells. Methods: PC-3 cells were treated with varying concentrations of NaBu, RUT, and their combinations. Cell viability was assessed using the WST-1 assay. Based on combination index values, selected treatments were further analyzed for apoptosis (Annexin V assay), intracellular reactive oxygen species (ROS) production, mRNA expression levels, and changes in cell and nuclear morphology. Results: The combined treatment of NaBu and RUT significantly reduced cell viability compared to individual treatments. Enhanced apoptotic induction and elevated ROS levels were observed in combination-treated cells, alongside notable changes in cellular and nuclear morphology and mRNA expression levels. Conclusions: NaBu and RUT combination therapy exhibits a synergistic anticancer effect in mCRPC cells by inhibiting cell viability, inducing apoptosis, and increasing ROS production. These findings suggest a promising therapeutic approach that warrants further investigation to elucidate the underlying molecular mechanisms and assess its potential in preclinical and clinical settings.

Tumor regression after neoadjuvant hormonal therapy in high risk prostate cancer: pathological outcomes from a randomized phase II trial

PURPOSE

High-risk localized prostate cancer (HRLPC) commonly progresses to metastatic disease after local treatment. Neoadjuvant androgen deprivation therapy (nADT) before radical prostatectomy (RP) has recently been suggested to improve early oncological outcomes in HRLPC. We aimed to perform an exploratory analysis of the pathological outcomes from a prospective trial testing nADT before RP.

METHODS

Prospective, single-centered, phase II, randomized trial performed between October 2018 and July 2021. Random assignment (1:1) for nADT modalities: goserelin (10.8 mg) plus abiraterone acetate (1000 mg/d) plus prednisone (5 mg/d), with or without apalutamide (240 mg/d) for 12 weeks, followed by RP (within 30 days) and extended lymph node dissection. Baseline clinical and pathological variables were assessed in needle biopsies before nADT. Tumor regression was histologically evaluated in surgical specimens using the residual cancer burden index (RCB).

RESULTS

Sixty-two patients reached the surgical phase. Good response (RCB ≤ 0.25 cm³) was achieved in 14 patients (22.5%). Overall stage migration rate between baseline status (MRI before nADT) and final status (after surgery) was 27.4%. Late stage detection (high tumor burden, perineural invasion) and altered PTEN/ERG immunostatus showed significant association with poor response in univariate analysis. Higher baseline tumor burden was the only independent factor related to poor response in multivariate analysis.

CONCLUSIONS

There are subgroups of patients, such as those with low baseline cancer burden and PTEN/ERG wild-type status, more likely to achieve good response with nADT. In the case of long term oncological benefit to be proven, nADT might be an additional therapeutic resource for these patients.

Second-line treatment options in metastatic castration-resistant prostate cancer after progression on first-line androgen-receptor targeting therapies: A systematic review and Bayesian network analysis

OBJECTIVE

To summarize and indirectly compare the efficacy and safety of different second-line systematic therapies after first-line androgen-receptor targeting therapies (ARTs) for biomarker-unselected metastatic castration-resistant prostate cancer (mCRPC) patients.

METHODS

Studies published in English up to May 2023 were identified in PubMed, Web of Science and ASCO-GU 2023. Studies accessing the efficacy and safety of second-line systematic therapies after first-line ARTs for biomarker-unselected mCRPC patients were eligible for current systematic review and network meta-analysis (NMA).

RESULTS

Thirty-two studies with 5388 patients and 10 unique treatment modalities met our inclusion criteria. Current evidence suggested that docetaxel (DOC) combined with the same ART as first-line (ART1) (ART1 + DOC) were associated with significantly improved PSA response, PSA progression-free survival (PFS) and clinical or radiographic PFS (rPFS) compared with other reported second-line systematic therapies, including DOC. An increase in toxicity was observed with ART1 + DOC. Our NMA indicated that DOC monotherapy was only inferior to ART1 + DOC in improvement disease outcomes. The incidence of toxicity between patients received second-line DOC and an alternative ART (ART2) was similar.

CONCLUSION

The available evidence reviewed in our work suggested a clinical benefit of DOC nomotherapy and DOC plus ART1 as the second-line systematic therapy for biomarker-unselected mCRPC patients progressed on a first-line ART. More studies and RCTs are needed to evaluate the optimal second-line treatments for mCRPC patients with one prior first-line ART.

Lower baseline testosterone level is related to earlier development of castration resistance in metastatic prostate cancer: a multi-center cohort study

Purpose

In the era of concurrent combination therapy in metastatic hormone sensitive prostate cancer, the impact of the testosterone level before initiating androgen deprivation therapy on treatment outcome is still uncertain. We aimed to investigate its effect on time-to-castration-resistance in a metastatic hormone sensitive prostate cancer cohort.

Methods

This is a multi-center retrospective study of 5 databases from China, Japan, Austria and Spain including 258 metastatic hormone sensitive prostate cancer patients with androgen deprivation therapy initiated between 2002 and 2021. Baseline testosterone was divided into high and low groups using 12 nmol/L as cutoff level. Primary outcome was time-to-castration-resistance. Secondary outcomes were survival functions. Kaplan-Meier method was employed to evaluate the correlation between baseline testosterone and time-to-castration-resistance. Subgroup analysis was performed to elucidate the effect of upfront combination-therapy and metastatic volume.

Results

Median age was 72 years. Median follow-up time was 31 months. Median pre-treatment prostate-specific-antigen level was 161 ng/mL. Majority of case were graded as International-Society-of-Urological-Pathology grade 5 (63.6%). 57.8% patients had high volume disease and 69.0% received upfront combination treatment. 44.6% of the cohort developed castration-resistance. The low testosterone group demonstrated shorter mean-time-to-castration-resistance (19.0 vs 22.4 months, p=0.031). The variance was more significant in patients without combination therapy (13.2 vs 26.3 months, p=0.015). Cancer-specific and overall survival were inferior in the low baseline testosterone level group without receiving combination therapy (p=0.001).

Conclusions

Lower pre-treatment testosterone level is correlated to shorter time-to-castration resistance and worse survival in metastatic prostate cancer patients without upfront combination therapy. Those with low baseline testosterone should be encouraged to adopt combination therapy to delay progression.

Influence of the Hypersensitivity to Low Dose Phenomenon on the Tumor Response to Hypofractionated Stereotactic Body Radiation Therapy

Stereotactic body radiation therapy (SBRT) has made the hypofractionation of high doses delivered in a few sessions more acceptable. While the benefits of hypofractionated SBRT have been attributed to additional vascular, immune effects, or specific cell deaths, a radiobiological and mechanistic model is still needed. By considering each session of SBRT, the dose is divided into hundreds of minibeams delivering some fractions of Gy. In such a dose range, the hypersensitivity to low dose (HRS) phenomenon can occur. HRS produces a biological effect equivalent to that produced by a dose 5-to-10 times higher. To examine whether HRS could contribute to enhancing radiation effects under SBRT conditions, we exposed tumor cells of different HRS statuses to SBRT. Four human HRS-positive and two HRS-negative tumor cell lines were exposed to different dose delivery modes: a single dose of 0.2 Gy, 2 Gy, 10 × 0.2 Gy, and a single dose of 2 Gy using a non-coplanar isocentric minibeams irradiation mode were delivered. Anti-γH2AX immunofluorescence, assessing DNA double-strand breaks (DSB), was applied. In the HRS-positive cells, the DSB produced by 10 × 0.2 Gy and 2 Gy, delivered by tens of minibeams, appeared to be more severe, and they provided more highly damaged cells than in the HRS-negative cells, suggesting that more severe DSB are induced in the "SBRT modes" conditions when HRS occurs in tumor. Each SBRT session can be viewed as hyperfractionated dose delivery by means of hundreds of low dose minibeams. Under current SBRT conditions (i.e., low dose per minibeam and not using ultra-high dose-rate), the response of HRS-positive tumors to SBRT may be enhanced significantly. Interestingly, similar conclusions were reached with HRS-positive and HRS-negative untransformed fibroblast cell lines, suggesting that the HRS phenomenon may also impact the risk of post-RT tissue overreactions.

Combination of radiotherapy and targeted therapy for HER2-positive breast cancer brain metastases

Radiotherapy and targeted therapy are essential treatments for patients with brain metastases from human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, the combination of radiotherapy and targeted therapy still needs to be investigated, and neurotoxicity induced by radiotherapy for brain metastases has also become an important issue of clinical concern. It remained unclear how to achieve the balance of efficacy and toxicity with the application of new radiotherapy techniques and new targeted therapy drugs. This article reviews the benefits and potential risk of combining radiotherapy and targeted therapy for HER2-positive breast cancer with brain metastases.