Effectiveness and tolerability of targeted drugs for the treatment of metastatic castration-resistant prostate cancer: a network meta-analysis of randomized controlled trials

Independent association between prostate-specific antigen nadir and PSA progression-free survival in first-line abiraterone acetate treatment in castration-resistant prostate cancer patients: a pilot study

Background

There is limited evidence regarding the correlation between prostate-specific antigen (PSA) kinetics and clinical outcomes. Therefore, after regulating other covariates, we studied patients with castration-resistant prostate cancer who received abiraterone acetate as the first-line treatment. In this study, we investigated whether time to PSA nadir was independently associated with PSA progression-free survival (PFS).

Methods

As a retrospective cohort study, this study contained a total of 77 castration-resistant prostate cancer patients who received abiraterone acetate from October 2015 to April 2021 in a Chinese hospital. The dependent variable was PSA-PFS. The objective independent variable was time to PSA nadir (TTPN). Covariates involved in this study included age, duration of androgen deprivation therapy (ADT), PSA level at baseline, time of 50% PSA decline, time of PSA decline to nadir, Gleason score, bone metastasis, previous treatment, PSA decline <50% in 3 months, PSA to nadir in 3 months, PSA decline <90%, PSA decline <0.2 ng/mL, and PSA flare.

Results

For the 77 subjects, their mean age was 72.70 ± 8.08 years. Fully calibrated linear regression findings indicated that PSA decline and kinetics were positively associated with PFS (months) after adjusting confounders (β = 0.77, 95% CI: 0.11-1.44). A non-linear relationship was not detected between PSA decline or PSA kinetics and progression-free survival.

Conclusion

According to the data of this study, there was a correlation between early PSA changes and patients treated with abiraterone acetate.

Macrophages as a Therapeutic Target in Metastatic Prostate Cancer: A Way to Overcome Immunotherapy Resistance?

Prostate cancer (PC) is the most common malignancy and the fifth cause of cancer death in men. The treatment for localized or locally advanced stages offers a high probability of cure. Even though the therapeutic landscape has significantly improved over the last decade, metastatic PC (mPC) still has a poor prognosis mainly due to the development of therapy resistance. In this context, the use of immunotherapy alone or in combination with other drugs has been explored in recent years. However, T-cell directed immune checkpoint inhibitors (ICIs) have shown limited activity with inconclusive results in mPC patients, most likely due to the highly immunosuppressive PC tumor microenvironment (TME). In this scenario, targeting macrophages, a highly abundant immunosuppressive cell type in the TME, could offer a new therapeutic strategy to improve immunotherapy efficacy. In this review, we summarize the growing field of macrophage-directed immunotherapies and discuss how these could be applied in the treatment of mPC, focusing on their combination with ICIs.

177Lu-PSMA Radioligand Therapy Is Favorable as Third-Line Treatment of Patients with Metastatic Castration-Resistant Prostate Cancer. A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

In this systematic review and network meta-analysis (NMA), we aimed to assess the benefits and harms of third-line (L3) treatments in randomized controlled trials (RCTs) of patients with metastatic castration-resistant prostate cancer (mCRPC). Two reviewers searched for publications from 1 January 2006 to 30 June 2021. The review analyzed seven RCTs that included 3958 patients and eight treatments. Treatment with prostate-specific membrane antigen (PSMA)-based radioligand therapy (PRLT) resulted in a 1.3-times-higher rate of median PSA decline ≥50% than treatment with abiraterone, enzalutamide, mitoxantrone, or cabazitaxel (p = 0.00001). The likelihood was 97.6% for PRLT to bring about the best PSA response, out of the examined treatments. PRLT resulted in a 1.1-times-higher six-month rate of median radiographic progression-free survival. Treatment with PRLT in the VISION trial resulted in 1.05-times-higher twelve-month median overall survival than L3 treatment with cabazitaxel in other RCTs. PRLT more often resulted in severe thrombocytopenia and less often in severe leukopenia than did cabazitaxel. In conclusion, for patients with mCRPC, L3 treatment with PRLT is highly effective and safe.

Antimicrobial Activity of 1,3,4-Oxadiazole Derivatives

The worldwide development of antimicrobial resistance forces scientists to search for new compounds to which microbes would be sensitive. Many new structures contain the 1,3,4-oxadiazole ring, which have shown various antimicrobial activity, e.g., antibacterial, antitubercular, antifungal, antiprotozoal and antiviral. In many publications, the activity of new compounds exceeds the activity of already known antibiotics and other antimicrobial agents, so their potential as new drugs is very promising. The review of active antimicrobial 1,3,4-oxadiazole derivatives is based on the literature from 2015 to 2021.

Whole-Body [18F]-Fluoride PET SUV Imaging to Monitor Response to Dasatinib Therapy in Castration-Resistant Prostate Cancer Bone Metastases: Secondary Results from ACRIN 6687

ACRIN 6687, a multi-center clinical trial evaluating differential response of bone metastases to dasatinib in men with metastatic castration-resistant prostate cancer (mCRPC), used [¹⁸F]-fluoride (NaF) PET imaging. We extend previous ACRIN 6687 dynamic imaging results by examining NaF whole-body (WB) static SUV PET scans acquired after dynamic scanning. Eighteen patients underwent WB NaF imaging prior to and 12 weeks into dasatinib treatment. Regional VOI analysis of the most NaF avid bone metastases and an automated whole-body method using Quantitative Total Bone Imaging software (QTBI; AIQ Solutions, Inc., Madison, WI, USA) were used. We assessed differences in tumor and normal bone, between pre- and on-treatment dasatinib, and evaluated parameters in association with PFS and OS. Significant decrease in average SUV_max and average SUV_peak occurred in response to dasatinib. Univariate and multivariate analysis showed NaF uptake had significant association with PFS. Pharmacodynamic changes with dasatinib in tumor bone can be identified by WB NaF PET in men with mCRPC. WB PET has the benefit of examining the entire body and is less complicated than single FOV dynamic imaging.

Influence of the HDAC Inhibitor Valproic Acid on the Growth and Proliferation of Temsirolimus-Resistant Prostate Cancer Cells In Vitro

The mechanistic target of rapamycin (mTOR) is elevated in prostate cancer, making this protein attractive for tumor treatment. Unfortunately, resistance towards mTOR inhibitors develops and the tumor becomes reactivated. We determined whether epigenetic modulation by the histone deacetylase (HDAC) inhibitor, valproic acid (VPA), may counteract non-responsiveness to the mTOR inhibitor, temsirolimus, in prostate cancer (PCa) cells. Prostate cancer cells, sensitive (parental) and resistant to temsirolimus, were exposed to VPA, and tumor cell growth behavior compared. Temsirolimus resistance enhanced the number of tumor cells in the G2/M-phase, correlating with elevated cell proliferation and clonal growth. The cell cycling proteins cdk1 and cyclin B, along with Akt-mTOR signaling increased, whereas p19, p21 and p27 decreased, compared to the parental cells. VPA significantly reduced cell growth and up-regulated the acetylated histones H3 and H4. Cdk1 and cyclin B decreased, as did phosphorylated mTOR and the mTOR sub-complex Raptor. The mTOR sub-member Rictor and phosphorylated Akt increased under VPA. Knockdown of cdk1, cyclin B, or Raptor led to significant cell growth reduction. HDAC inhibition through VPA counteracts temsirolimus resistance, probably by down-regulating cdk1, cyclin B and Raptor. Enhanced Rictor and Akt, however, may represent an undesired feedback loop, which should be considered when designing future therapeutic regimens.

Timing of androgen deprivation monotherapy and combined treatments in castration-sensitive and castration-resistant prostate cancer: a narrative review

PURPOSE

Standard androgen deprivation therapy (ADT) can be initiated early at the time of diagnosis in asymptomatic castration-sensitive advanced prostate cancer. This definition has recently been expanded to also include an early combined treatment with standard ADT and new antihormonal drugs. We aimed to present the best available evidence for the timing of initiation of ADT monotherapy and combined treatments in castration-sensitive/-resistant prostate cancer.

METHODS

For this narrative review, we searched Cochrane reviews in the Cochrane Library, systematic reviews and randomized controlled trials in MEDLINE, phase III and ongoing trials in ClinicalTrials.gov and screened the reference lists to extract articles of interest. One author screened the references which were finally included after assessing their relevance through discussion with other experts in the field.

RESULTS

The identified references were grouped by medication (standard ADT, androgen biosynthesis inhibitor, androgen receptor antagonists or combined therapies) and tumor stage (castration sensitive or resistant). The evidence was narratively summarized and discussed in the context of the current therapeutic landscape.

CONCLUSIONS

Early standard ADT can reduce symptoms of disease progression and may extend progression-free and overall survival. The patient should be well informed about the higher rates of treatment-related side effects. Deferring standard ADT might be indicated only for well-informed or unfit patients. Early standard ADT is increasingly combined with new antihormonal drugs in castration-sensitive metastatic prostate cancer to gain additional survival and quality of life benefits. Combined treatment at the time of development of castration-resistant disease is well established.