Advanced prostate cancer update 2018

Oral Toxicities of PSMA-Targeted Immunotherapies for The Management of Prostate Cancer

INTRODUCTION

Prostate Specific Membrane Antigen (PSMA)-targeted radionucleotide therapy has been shown to cause dry mouth, but the oral manifestations of PSMA-targeted immunotherapy have not been extensively studied. The aim of this study was to describe and quantify the oral manifestations of PSMA-targeted immunotherapies (bispecific antibodies or Chimeric Antigen Receptor T cell therapies) in the management of metastatic castration resistant prostate cancer.

PATIENTS AND METHODS

We performed a retrospective analysis of the oral toxicities of PSMA-targeted immunotherapies of the patients seen at a single institution's cancer center between 2020 and 2023. Descriptive statistics were used to summarize the data.

RESULTS

In a total of 19 patients treated with PSMA-targeted immunotherapies between 2020 and 2023, 9 patients (47%) experienced the following oral toxicities: xerostomia (n = 6; 32%), mucositis (n = 2; 10%), dysgeusia, dry throat and teeth sensitivity in (n = 1 each; 5%), respectively. Oral infections, such as candidiasis and herpes simplex, were not observed in any patients. Mucositis was managed with salt rinses and resolved within few months from onset. Xerostomia persisted in all the patients (median: 306 days, range: 98-484 days) among those who reported dry mouth at the time of data collection, despite treatment with salivary stimulants (n = 5; 83%). Dysgeusia was also persistent, although it was not specifically treated.

CONCLUSIONS

Patients treated with PSMA-targeted immunotherapies for prostate cancer can present with various short-term and long-term off-tumor on-target oral toxicities including xerostomia and dysgeusia that may affect quality of life. This study serves as a foundation to future prospective studies with a larger sample size and also helps oncologists managing prostate cancer patients with targeted immunotherapies to familiarize common oral toxicities. Furthermore, we emphasize the importance of oral medicine consultation for a comprehensive oral examination and management of oral complications.

The discovery of novel sanjuanolide derivatives as chemotherapeutic agents targeting castration-resistant prostate cancer

There remains a critical need for more effective therapies for the treatment of castration-resistant prostate cancer (CRPC), which is the leading cause of death in patients with prostate cancer. In this study, a series of sanjuanolide derivatives were designed, synthesized and evaluated as potential anti-CRPC agents. Most of the compounds had excellent selectivity for CRPC cells with IC₅₀ values < 20 µM. Moreover, minimal side effects on human normal hepatic MIHA cells and normal prostatic stromal myofibroblast WPMY-1 cells were observed, with IC₅₀ > 100 µM. The representative compound S07 slowed down the proliferative rate of CRPC cells, promoted cell apoptosis and caused G2/M phase accumulation, as well as G1/G0 phase reduction. Further mechanistic studies showed that S07 treatment triggered intense DNA damage and provoked strong DNA damage response in a dose-dependent manner. These findings suggested that sanjuanolide derivatives, especially S07, selectively induced CRPC cell death by triggering intense DNA damage and DNA damage response.

Genetic biomarkers to guide poly(ADP-ribose) polymerase inhibitor precision treatment of prostate cancer

Precision therapy for a subgroup of genetically defined metastatic castration-resistant prostate cancer patients may become a reality in the near future. DNA damage repair gene mutated prostate cancer might be vulnerable to treatment with PARP inhibitors (PARPi). PARPi clinical trials for prostate cancer investigate both germline and somatic genomic alterations of 43 genes for the applicability as genomic biomarker of PARPi sensitivity. Clinical trials with preliminary results show that BRCA2 and BRCA1, but also ATM, additionally BRIP1, FANCA, CDK12 and PALB2 may affect clinical end points, and may be potential candidates for genome-guided patient selection in PARPi treatment of prostate cancer.

Effects of Xeroderma pigmentosum group C polymorphism on the likelihood of prostate cancer

Background

Numerous studies have assessed the association between xeroderma pigmentosum complementation group C (XPC) polymorphisms and susceptibility of prostate cancer (PCa); however, the findings remain inconsistent.

Methods

We performed an updated analysis utilizing data from electronic databases to obtain a more accurate estimation of the relationship between XPC rs2228001 A/C polymorphism and PCa risk. We further used in silico tools to investigate this correlation.

Results

Totally, 5,305 PCa cases and 6,499 control subjects were evaluated. When all studies pooled together, we detected no positive result (recessive genetic model: OR = 1.14, 95% CI = 0.93‐1.40, P_{heterogeneity} = 0.001, P = .212); nevertheless, the XPC rs2228001 A/C variant was associated with PCa risk in Asian descendants in the subgroup analysis (OR = 1.21, 95% CI = 1.01‐1.43, P_{heterogeneity} = 0.008, P = .034). In silico tools showed that more than 20 proteins can participate in the protein crosstalk with XPC. The expression of XPC was down‐regulated in all Gleason scores of prostate cancer.

Conclusions

The present study indicated that the XPC rs2228001 A/C variant may be associated with elevated PCa risk in Asian patients.

Salinomycin triggers endoplasmic reticulum stress through ATP2A3 upregulation in PC-3 cells

Background

Salinomycin is a monocarboxylic polyether antibiotic and is a potential chemotherapy drug. Our previous studies showed that salinomycin inhibited cell growth and targeted CSCs in prostate cancer. However, the precise target of salinomycin action is unclear.

Methods

In this work, we analyzed and identified differentially expressed genes (DEGs) after treatment with or without salinomycin using a gene expression microarray in vitro (PC-3 cells) and in vivo (NOD/SCID mice xenograft model generated from implanted PC-3 cells). Western blotting and immunohistochemical staining were used to analyze the expression of ATP2A3 and endoplasmic reticulum (ER) stress biomarkers. Flow cytometry was used to analyze the cell cycle, apoptosis and intracellular Ca²⁺ concentration.

Results

A significantly upregulated gene, ATPase sarcoplasmatic/endoplasmatic reticulum Ca²⁺ transporting 3 (ATP2A3), was successfully identified. In subsequent studies, we found that ATP2A3 overexpression could trigger ER stress and exert anti-cancer effects in PC-3 and DU145 cells. ATP2A3 was slightly expressed, but the ER stress biomarkers showed strong staining in prostate cancer tissues. We also found that salinomycin could trigger ER stress, which might be related to ATP2A3-mediated Ca²⁺ release in PC-3 cells. Furthermore, we found that salinomycin-triggered ER stress could promote apoptosis and thus exert anti-cancer effects in prostate cancer cells.

Conclusion

This study demonstrates that ATP2A3 might be one of the potential targets for salinomycin, which can inhibit Ca²⁺ release and trigger ER stress to exert anti-cancer effects.