Efficacy and safety of post-docetaxel therapies in metastatic castration-resistant prostate cancer: a systematic review of the literature

HuR promotes castration-resistant prostate cancer progression by altering ERK5 activation via posttranscriptional regulation of BCAT1

BACKGROUND

Castration-resistant prostate cancer (CRPC) is refractory to hormone treatment, and the underlying mechanism has not been fully elucidated. This study aimed to clarify the role and mechanism of Human antigen R (HuR) as a therapeutic target for CRPC progression.

METHODS

HuR was knocked out by Cas9 or inhibited by the HuR-specific inhibitor KH-3 in CRPC cell lines and in a mouse xenograft model. The effects of HuR inhibition on tumour cell behaviors and signal transduction were examined by proliferation, transwell, and tumour xenograft assays. Posttranscriptional regulation of BCAT1 by HuR was determined by half-life and RIP assays.

RESULTS

HuR knockout attenuated the proliferation, migration, and invasion of PC3 and DU145 cells in vitro and inhibited tumour progression in vivo. Moreover, BCAT1 was a direct target gene of HuR and mediated the oncogenic effect of HuR on CRPC. Mechanistically, HuR directly interacted with BCAT1 mRNA and upregulated BCAT1 expression by increasing the stability and translation of BCAT1, which activated ERK5 signalling. Additionally, the HuR-specific inhibitor KH-3 attenuated CRPC progression by disrupting the HuR-BCAT1 interaction.

CONCLUSIONS

We confirmed that the HuR/BCAT1 axis plays a crucial role in CRPC progression and suggest that inhibiting the HuR/BCAT1 axis is a promising therapeutic approach for suppressing CRPC progression.

Treatment landscape and burden of disease in metastatic castration-resistant prostate cancer: systematic and structured literature reviews

Purpose

Metastatic castration-resistant prostate cancer (mCRPC) is a lethal disease that imposes a major burden on patients and healthcare systems. Three structured literature reviews (treatment guidelines, treatment landscape, and human/clinical/patient burden) and one systematic literature review (economic burden) were conducted to better understand the disease burden and unmet needs for patients with late-stage mCRPC, for whom optimal treatment options are unclear.

Methods

Embase®, MEDLINE®, MEDLINE® In-Process, the CENTRAL database (structured and systematic reviews), and the Centre for Reviews and Dissemination database (systematic review only) were searched for English-language records from 2009 to 2021 to identify mCRPC treatment guidelines and studies related to the treatment landscape and the humanistic/economic burden of mCRPC in adult men (aged ≥18 years) of any ethnicity.

Results

In total, six records were included for the treatment patterns review, 14 records for humanistic burden, nine records for economic burden, three records (two studies) for efficacy, and eight records for safety. Real-world treatment patterns were broadly aligned with treatment guidelines and provided no optimal treatment sequencing beyond second line other than palliative care. Current post-docetaxel treatments in mCRPC are associated with adverse events that cause relatively high rates of treatment discontinuation or disruption. The humanistic and economic burdens associated with mCRPC are high.

Conclusion

The findings highlight a lack of treatment options with novel mechanisms of action and more tolerable safety profiles that satisfy a risk-to-benefit ratio aligned with patient needs and preferences for patients with late-stage mCRPC. Treatment approaches that improve survival and health-related quality of life are needed, ideally while simultaneously reducing costs and healthcare resource utilization.

Immunoproteasome inhibition prevents progression of castration-resistant prostate cancer

BACKGROUND

Castration-resistant prostate cancer (CRPC) is refractory to hormone treatment. This study aims to explore the effect and underlying mechanisms of immunoproteasome inhibition, a novel immunotherapy, on the progression of CRPC.

METHODS

The immunoproteasome subunit LMP7 was silenced by using gene knockout or inhibited by the epoxyketone inhibitor ONX 0914 in a mouse CRPC tumour graft model and in interferon-γ-pretreated human CRPC cell lines in vitro.

RESULTS

CRPC tissues reveal a significant "tumour-elicited" Th17-type inflammatory response which induces immunoproteasome subunit expression. LMP7 deficiency in host mice or in CRPC tumour grafts had no effect on the "tumour-elicited" Th17-type inflammatory response and tumour progression. However, the selective LMP7 inhibitor ONX 0914 strongly suppressed the "tumour-elicited" Th17-type inflammatory response and CRPC tumour progression. Treatment of wild-type mice receiving LMP7-deficient CRPC tumour grafts with ONX 0914 further suggested that immunoproteasome inhibition prevents CRPC progression through suppressing IL-17-induced angiogenesis and epithelial-mesenchymal transition via inactivation of COX-2/VEGF-A signalling and β-catenin/Snail signalling. Treatment of LMP7-deficient mice receiving wild-type CRPC tumour grafts with ONX 0914 and inhibition of LMP7 in PC3 and 22Rv.1 cells with ONX 0914 showed that immunoproteasome inhibition also prevents CRPC progression through inducing CRPC cell apoptosis via activation of the unfolded protein response.

CONCLUSIONS

We define a critical role of the immunoproteasome in CRPC and propose immunoproteasome inhibition as a promising therapeutic approach to suppress CRPC progression.

Drug Repurposing: The Mechanisms and Signaling Pathways of Anti-Cancer Effects of Anesthetics

Cancer is one of the leading causes of death worldwide. There are only limited treatment strategies that can be applied to treat cancer, including surgical resection, chemotherapy, and radiotherapy, but these have only limited effectiveness. Developing a new drug for cancer therapy is protracted, costly, and inefficient. Recently, drug repurposing has become a rising research field to provide new meaning for an old drug. By searching a drug repurposing database ReDO_DB, a brief list of anesthetic/sedative drugs, such as haloperidol, ketamine, lidocaine, midazolam, propofol, and valproic acid, are shown to possess anti-cancer properties. Therefore, in the current review, we will provide a general overview of the anti-cancer mechanisms of these anesthetic/sedative drugs and explore the potential underlying signaling pathways and clinical application of these drugs applied individually or in combination with other anti-cancer agents.

Inhibition of Janus Kinase 1 synergizes docetaxel sensitivity in prostate cancer cells

Prostate cancer (PCa) is the second most common malignancy and is the fifth leading cause of cancer mortality among men globally. Docetaxel-based therapy remains the first-line treatment for metastatic castration-resistant prostate cancer. However, dose-limiting toxicity including neutropenia, myelosuppression and neurotoxicity is the major reason for docetaxel dose reductions and fewer cycles administered, despite a recent study showing a clear survival benefit with increased total number of docetaxel cycles in PCa patients. Although previous studies have attempted to improve the efficacy and reduce docetaxel toxicity through drug combination, no drug has yet demonstrated improved overall survival in clinical trial, highlighting the challenges of improving the activity of docetaxel monotherapy in PCa. Herein, we identified 15 lethality hits for which inhibition could enhance docetaxel sensitivity in PCa cells via a high-throughput kinome-wide loss-of-function screen. Further drug-gene interactions analyses identified Janus kinase 1 (JAK1) as a viable druggable target with existing experimental inhibitors and FDA-approved drugs. We demonstrated that depletion of endogenous JAK1 enhanced docetaxel-induced apoptosis in PCa cells. Furthermore, inhibition of JAK1/2 by baricitinib and ruxolitinib synergizes docetaxel sensitivity in both androgen receptor (AR)-negative DU145 and PC3 cells, but not in the AR-positive LNCaP cells. In contrast, no synergistic effects were observed in cells treated with JAK2-specific inhibitor, fedratinib, suggesting that the synergistic effects are mainly mediated through JAK1 inhibition. In conclusion, the combination therapy with JAK1 inhibitors and docetaxel could be a useful therapeutic strategy in the treatment of prostate cancers.

Use of miR‑145 and testicular nuclear receptor 4 inhibition to reduce chemoresistance to docetaxel in prostate cancer

The human testicular nuclear receptor 4 (TR4) is a critical regulatory gene for the progression of prostate cancer (PCa). Although it has been revealed that TR4 causes chemoresistance in PCa via the activation of octamer-binding transcription factor 4 (OCT4), the detailed mechanism remains unexplored. In the present study, it was revealed that inhibition of TR4 by shRNA in PCa enhanced the sensitivity to docetaxel in vitro and in vivo. TR4 induced the downregulation of miR-145 by directly binding it to the promoter of miR-145, which was confirmed by chromatin immunoprecipitation analysis and luciferase assay. The overexpression of miR-145 suppressed both the chemoresistance and the expression of OCT4 mRNA and protein. Additionally, the TR4 shRNA mediated re-sensitization to docetaxel, along with the downregulated expression of OCT4, were reversed by the concurrent inhibition of miR-145. The luciferase assay revealed that the activity of the wild-type OCT4 3′ untranslated region reporter was suppressed. This suppression diminished when the miR-145 response element mutated. These findings suggest an undescribed regulatory pathway in PCa, by which TR4 directly suppressed the expression of miR-145, thereby inhibiting its direct target OCT4, leading to the promotion of chemoresistance in PCa.

Sulforaphane Reduces Prostate Cancer Cell Growth and Proliferation In Vitro by Modulating the Cdk-Cyclin Axis and Expression of the CD44 Variants 4, 5, and 7

Prostate cancer patients whose tumors develop resistance to conventional treatment often turn to natural, plant-derived products, one of which is sulforaphane (SFN). This study was designed to determine whether anti-tumor properties of SFN, identified in other tumor entities, are also evident in cultivated DU145 and PC3 prostate cancer cells. The cells were incubated with SFN (1–20 µM) and tumor cell growth and proliferative activity were evaluated. Having found a considerable anti-growth, anti-proliferative, and anti-clonogenic influence of SFN on both prostate cancer cell lines, further investigation into possible mechanisms of action were performed by evaluating the cell cycle phases and cell-cycle-regulating proteins. SFN induced a cell cycle arrest at the S- and G2/M-phase in both DU145 and PC3 cells. Elevation of histone H3 and H4 acetylation was also evident in both cell lines following SFN exposure. However, alterations occurring in the Cdk-cyclin axis, modification of the p19 and p27 proteins and changes in CD44v4, v5, and v7 expression because of SFN exposure differed in the two cell lines. SFN, therefore, does exert anti-tumor properties on these two prostate cancer cell lines by histone acetylation and altering the intracellular signaling cascade, but not through the same molecular mechanisms.

CLC-3 and SOX2 regulate the cell cycle in DU145 cells

Sex determining region Y-box 2 (SOX2) is a transcription factor that serves a role in numerous different types of malignant cancer. Altered expression of chloride channel proteins has been described in a variety of malignancies. However, the association between SOX2 and chloride channel proteins is not yet fully understood. The present study investigated the association between SOX2 and chloride voltage-gated channel 3 (CLC-3) in prostate cancer. Flow cytometry demonstrated that the inactivation of CLC-3 or SOX2 arrested cell cycle progression in the G₀/G₁ phase. Furthermore, CLC-3 was observed to bind to SOX2, and vice versa, by co-immunoprecipitation. SOX2 appears to initiate and maintain prostate cancer tumorigenesis, in part, by modulating the cell cycle. These findings indicate the potential of SOX2 and CLC-3 as targets for the development of multi-targeted therapeutics.

Health-Related Quality-of-Life Outcomes with Actinium-225-Prostate-Specific Membrane Antigen-617 Therapy in Patients with Heavily Pretreated Metastatic Castration-Resistant Prostate Cancer

Aims

Actinium-225 (²²⁵Ac) labeled prostate-specific membrane antigen (PSMA)-617 is a novel treatment modality in the management of metastatic castration-resistant prostate cancer (mCRPC). The present study was conducted to assess the impact of ²²⁵Ac-PSMA-617 therapy on the quality-of-life of patients with heavily pretreated mCRPC using the National Comprehensive Cancer Network-Functional Assessment of Cancer Therapy-Prostate Symptom Index-17 (NCCN-FACT-FPSI-17) questionnaire.

Materials and Methods

This was a retrospective single-center study where data of consecutive heavily pretreated mCRPC patients treated with ²²⁵Ac-PSMA-617 from January 2019 to February 2020, was collected and analyzed for the biochemical response, quality-of-life outcomes and treatment-related toxicity.

Results

Eleven heavily pretreated mCRPC patients received a median cumulative dose of 8.3 MBq (interquartile range [IQR] 5.6-20.4 MBq) ²²⁵Ac-PSMA-617 over 1-4 cycles. 5/11 patients (46%) showed a ≥50% decline in Prostate Specific Antigen (PSA), while stable values and PSA progression were observed in 3/11 (27%) patients each. Pre- and post-therapy NCCN-FACT-FPSI-17 questionnaires revealed statistically significant improvement in the total FPSI score (P = 0.003) as well as the disease-related symptoms-physical (P = 0.004) and disease-related symptoms-emotional (P = 0.046) subscores. Among the physical symptoms, significant improvement was noted with respect to pain, difficulty in urination, bone pain, fatigue, and restriction in physical activity. No significant change was noted in the treatment side-effects subscore. Of the treatment-related adverse effects, Grade 3 dryness of the mouth, anemia, and nephrotoxicity was observed in 1/11 patients (9%) each and Grade 3 thrombocytopenia in 2/11 patients (18%).

Conclusion

Health-related quality-of-life of the mCRPC patients improved significantly with ²²⁵Ac-PSMA-617 despite extensive pretreatment and advanced nature of the disease.

Expert recommendations on the management of patients with metastatic castration-resistant prostate cancer who progress after CHAARTED or LATITUDE

Objective

Our aim was to provide practical recommendations on the management of patients with metastatic castration-resistant prostate cancer (mCRPC) who have progressed after docetaxel plus androgen-deprivation therapy (ADT) or abiraterone plus ADT.

Methods

Systematic literature review (SLR), nominal group meeting, and Delphi process. A panel of 12 experts was established who defined the scope, users, and sections of the document. We performed an SLR in order to assess the efficacy and safety of available drugs in patients with mCRPC. Abstracts from the American Society of Oncology and European Society for Medical Oncology meetings were also examined. The results were discussed during an expert meeting in which 14 recommendations were generated. The level of agreement with the recommendations was also tested by 13 additional experts following the Delphi process. Recommendations were voted by means of scores ranging from 0 (total disagreement) to 10 (total agreement). We defined agreement when at least 70% of the experts voted ⩾7. Next, we assigned a level of evidence and grade to the recommendation using the Oxford Centre for Evidence-based Medicine Levels of Evidence, following which the final document was drafted.

Results

The literature search did not find any articles meeting the inclusion criteria. Finally, 13 out of 14 recommendations were accepted after two Delphi rounds (two were modified after the first round). They pertain to general and individual case-based treatment recommendations.

Conclusions

In mCRPC patients who have progressed after docetaxel or abiraterone plus ADT in the metastatic hormone-sensitive prostate cancer setting, these recommendations may support treatment decision-making, due to the lack of evidence or other globally accepted sequencing algorithms.

Chitosan-based advanced materials for docetaxel and paclitaxel delivery: Recent advances and future directions in cancer theranostics

Paclitaxel (PTX) and docetaxel (DTX) are key members of taxanes with high anti-tumor activity against various cancer cells. These chemotherapeutic agents suffer from a number of drawbacks and it seems that low solubility in water is the most important one. Although much effort has been made in improving the bioavailability of PTX and DTX, the low bioavailability and minimal accumulation at tumor sites are still the challenges faced in PTX and DTX therapy. As a consequence, bio-based nanoparticles (NPs) have attracted much attention due to unique properties. Among them, chitosan (CS) is of interest due to its great biocompatibility. CS is a positively charged polysaccharide with the capability of interaction with negatively charged biomolecules. Besides, it can be processed into the sheet, micro/nano-particles, scaffold, and is dissolvable in mildly acidic pH similar to the pH of the tumor microenvironment. Keeping in mind the different applications of CS in the preparation of nanocarriers for delivery of PTX and DTX, in the present review, we demonstrate that how CS functionalized-nanocarriers and CS modification can be beneficial in enhancing the bioavailability of PTX and DTX, targeted delivery at tumor site, image-guided delivery and co-delivery with other anti-tumor drugs or genes.

Overall and progression-free survival with cabazitaxel in metastatic castration-resistant prostate cancer in routine clinical practice: the FUJI cohort

Background

Cabazitaxel is a treatment of metastatic castration-resistant prostate cancer (mCRPC) after docetaxel failure. The FUJI cohort aimed to confirm the real-life overall and progression-free survival (OS, PFS) and safety of cabazitaxel.

Methods

Multicentre, non-interventional cohort of French mCRPC patients initiating cabazitaxel between 2013 and 2015, followed 18 months.

Results

Four hundred one patients were recruited in 42 centres. At inclusion, median age was 70, main metastatic sites were bones (87%), lymph nodes (42%) and visceral (20%). 18% had cabazitaxel in 2nd-line treatment, 39% in 3rd-line and 43% in 4th-line or beyond. All had prior docetaxel, and 82% prior abiraterone, enzalutamide or both. Median duration of cabazitaxel treatment was 3.4 months. Median OS from cabazitaxel initiation was 11.9 months [95% CI: 10.1–12.9]. In multivariate analyses, grade ≥ 3 adverse events, visceral metastases, polymedication, and >5 bone metastases were associated with a shorter OS. Main grade ≥ 3 adverse events were haematological with 8% febrile neutropenia.

Conclusion

Real-life survival with cabazitaxel in FUJI was shorter than in TROPIC (pivotal trial, median OS 15.1 months) or PROSELICA (clinical trial 20 vs 25 mg/m², median OS, respectively, 13.4 and 14.5 months). There was no effect of treatment-line on survival. No unexpected adverse concerns were identified.

Study registration

It was registered with the European Medicines Agency EUPASS registry, available at www.encepp.eu, as EUPAS10391. It has been approved as an ENCEPP SEAL study.

EDB-FN Targeted Peptide-Drug Conjugates for Use against Prostate Cancer

Prostate cancer (PCa) is the most common malignancy in men and is the leading cause of cancer-related male mortality. A disulfide cyclic peptide ligand [CTVRTSADC] 1 has been previously found to target extra domain B of fibronectin (EDB-FN) in the extracellular matrix that can differentiate aggressive PCa from benign prostatic hyperplasia. We synthesized and optimized the stability of ligand 1 by amide cyclization to obtain [KTVRTSADE] 8 using Fmoc/tBu solid-phase chemistry. Optimized targeting ligand 8 was found to be stable in phosphate buffered saline (PBS, pH 6.5, 7.0, and 7.5) and under redox conditions, with a half-life longer than 8 h. Confocal microscopy studies demonstrated increased binding of ligand 8 to EDB-FN compared to ligand 1. Therefore, we hypothesized that the EDB-FN targeted peptides (1 and 8) conjugated with an anticancer drug via a hydrolyzable linker would provide selective cytotoxicity to the cancer cells. To test our hypothesis, we selected both the normal prostate cell line, RWPE-1, and the cancerous prostate cell lines, PC3, DU-145, LNCaP, and C4-2, to evaluate the anticancer activity of synthesized peptide–drug conjugates. Docetaxel (Doce) and doxorubicin (Dox) were used as anticancer drugs. Dox conjugate 13 containing disulfide linkage showed comparable cytotoxicity versus Dox after 72 h incubation in all the cancer cell lines, whereas it was found to be less cytotoxic on RWPE-1, suggesting that it can act as a Dox prodrug. Doce conjugate 14 was found to be less cytotoxic in all the cell lines as compared to drug alone.

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.

Recent Advances in Prostate Cancer Treatment and Drug Discovery

Novel drugs, drug sequences and combinations have improved the outcome of prostate cancer in recent years. The latest approvals include abiraterone acetate, enzalutamide and apalutamide which target androgen receptor (AR) signaling, radium-223 dichloride for reduction of bone metastases, sipuleucel-T immunotherapy and taxane-based chemotherapy. Adding abiraterone acetate to androgen deprivation therapy (ADT) in order to achieve complete androgen blockade has proven highly beneficial for treatment of locally advanced prostate cancer and metastatic hormone-sensitive prostate cancer (mHSPC). Also, ADT together with docetaxel treatment showed significant benefit in mHSPC. Ongoing clinical trials for different subgroups of prostate cancer patients include the evaluation of the second-generation AR antagonists enzalutamide, apalutamide and darolutamide, of inhibitors of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway, of inhibitors of DNA damage response, of targeted alpha therapy and of prostate-specific membrane antigen (PSMA) targeting approaches. Advanced clinical studies with immune checkpoint inhibitors have shown limited benefits in prostate cancer and more trials are needed to demonstrate efficacy. The identification of improved, personalized treatments will be much supported by the major progress recently made in the molecular characterization of early- and late-stage prostate cancer using “omics” technologies. This has already led to novel classifications of prostate tumors based on gene expression profiles and mutation status, and should greatly help in the choice of novel targeted therapies best tailored to the needs of patients.

Indirect treatment comparison of cabazitaxel for patients with metastatic castrate-resistant prostate cancer who have been previously treated with a docetaxel-containing regimen

Background

The objective of this study was to conduct an indirect treatment comparison between cabazitaxel, abiraterone and enzalutamide to determine the clinical efficacy and safety of cabazitaxel relative to comparators in the treatment of patients with metastatic castrate-resistant prostate cancer who progress on docetaxel-based therapies.

Methods

A systematic literature review was conducted to inform the network meta-analysis of cabazitaxel, abiraterone and enzalutamide. Due to a lack of head-to-head trials, studies with a comparator arm of best supportive care were included in the analysis. Overall survival, progression-free survival, and adverse events were compared within both Bayesian and Frequentist frameworks. The ratios for survival outcomes were estimated using hazard ratios (HR), and the ratios for adverse events between groups were estimated using odds ratios (ORs); uncertainty was reported as 95% confidence (Frequentist) and credible (Baysesian) Intervals.

Results

Three of thirteen trials identified for abstraction were relevant for analyses. Median overall survival was not statistically significantly different for abiraterone (HR = 1.04; 95% CI = 0.83–1.28) or enzalutamide (HR = 0.88; 95% CI = 0.69–1.11) when compared to cabazitaxel in the Bayesian analysis. Anaemia (OR = 3.71; 95% CI = 1.01–10.44), diarrhoea (OR = 16.60; 95% CI = 1.41–75.31) and haematuria (OR = 3.88; 95% CI = 1.03–10.09) were more likely to occur in the cabazitaxel group than the abiraterone group, while pyrexia risk was higher in cabazitaxel compared to enzalutamide (OR = 36.23; 95% CI = 1.14–206.40). Frequentist analyses produced similar results.

Conclusions

The scarcity of clinical studies and lack of a common comparator limited analyses. The adverse event results must be interpreted with caution as many were based on small numbers. The results from this analysis indicate comparable survival outcomes and adverse event profiles. As these pivotal studies may not reflect the contemporary treatment landscape and patient profiles, additional research, including head-to-head clinical trials and real world observational studies, should be conducted to further elucidate the beneficial effects of these therapies.

Third-line treatment and 177Lu-PSMA radioligand therapy of metastatic castration-resistant prostate cancer: a systematic review

Aims

There is a controversy as to the relative efficacy of ¹⁷⁷Lu prostate specific membrane antigen (PSMA) radioligand therapy (RLT) and third-line treatment for patients with metastatic castration-resistant prostate cancer (mCRPC). The aim of our systematic review was to elucidate whether ¹⁷⁷Lu-PSMA RLT and third-line treatment have similar effects and adverse effects (PROSPERO ID CRD42017067743).

Methods

The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Searches in Pubmed and Embase selected articles up to September 2017. A search in ClinicalTrials.gov indicated ongoing studies. The meta-analysis used the random-effects model.

Results

Twelve studies including 669 patients reported ¹⁷⁷Lu-PSMA RLT. Overall, 43% of the patients had a maximum decline of PSA of ≥50% following treatment with ¹⁷⁷Lu-PSMA RLT. The treatment with ¹⁷⁷Lu-PSMA-617 and ¹⁷⁷Lu-PSMA for imaging and therapy (I&T) had mainly transient adverse effects. Sixteen studies including 1338 patients reported third-line treatment. Overall, 21% of the patients had a best decline of PSA of ≥50% following third-line treatment. After third-line treatment with enzalutamide and cabazitaxel, adverse effects caused discontinuation of treatment for 10% to 23% of the patients. ¹⁷⁷Lu-PSMA RLT gave a best PSA decline ≥50% more often than third-line treatment (mean 44% versus 22%, p = 0.0002, t test). ¹⁷⁷Lu-PSMA RLT gave objective remission more often than third-line treatment (overall 31 of 109 patients versus 43 of 275 patients, p = 0.004, χ² test). Median survival was longer after ¹⁷⁷Lu-PSMA RLT than after third-line treatment, but the difference was not statistically significant (mean 14 months versus 12 months, p = 0.32, t test). Adverse effects caused discontinuation of treatment more often for third-line treatment than for ¹⁷⁷Lu-PSMA RLT (22 of 66 patients versus 0 of 469 patients, p < 0.001, χ² test).

Conclusions

As for patients with mCRPC, treatment with ¹⁷⁷Lu-PSMA-617 RTL and ¹⁷⁷Lu-PSMA I&T gave better effects and caused fewer adverse effects than third-line treatment.