Should Lutetium-prostate specific membrane antigen radioligand therapy for metastatic prostate cancer be used earlier in men with lymph node only metastatic prostate cancer?

Review on the Increasing Role for PSMA-Based Radioligand Therapy in Prostate Cancer

In 2021, two randomized controlled trials (RCTs), TheraP and VISION, demonstrated that 177Lu-PSMA-617 as monotherapy was more effective for the decline of PSA than the comparator third-line treatments.

METHODS

Our review summarizes new RCTs that add to the use of radioligand therapy (RLT) for patients with high-risk prostate cancer (PCa).

RESULTS

Four past and present RCTs included 1081 patients. An RCT, ENZA-p, studied first-line treatment of patients with metastatic castration-resistant PCa (mCRPC). A combination of enzalutamide (ENZA) and 177Lu-PSMA-617 gave longer progression-free survival than ENZA as monotherapy. Other RCTs of patients with mCRPC, including the PSMAfore, and SPLASH trials, showed 177Lu-PSMA-617 as second-line treatment gave better progression-free survival than androgen receptor pathway inhibitors (combined p value < 6.9 × 10-6).

CONCLUSIONS

Patients with PCa gain if they are given PSMA-RLT early in the treatment of PCa and as part of combination therapies.

Emerging Role of Nuclear Medicine in Prostate Cancer: Current State and Future Perspectives

Prostate cancer is the most frequent epithelial neoplasia after skin cancer in men starting from 50 years and prostate-specific antigen (PSA) dosage can be used as an early screening tool. Prostate cancer imaging includes several radiological modalities, ranging from ultrasonography, computed tomography (CT), and magnetic resonance to nuclear medicine hybrid techniques such as single-photon emission computed tomography (SPECT)/CT and positron emission tomography (PET)/CT. Innovation in radiopharmaceutical compounds has introduced specific tracers with diagnostic and therapeutic indications, opening the horizons to targeted and very effective clinical care for patients with prostate cancer. The aim of the present review is to illustrate the current knowledge and future perspectives of nuclear medicine, including stand-alone diagnostic techniques and theragnostic approaches, in the clinical management of patients with prostate cancer from initial staging to advanced disease.

PSMA-targeted radioligand therapy in prostate cancer: current status and future prospects

INTRODUCTION

The prostate-specific membrane antigen (PSMA) targeted radioligand therapy (PRLT) for the treatment of metastatic castration-resistant prostate cancer (mCRPC) patients has generated significant interest among the oncologic community, with several publications documenting good response rates and survival benefits with low toxicity profiles.

AREAS COVERED

Indications, patient preparation, dose administration, post-treatment imaging, dosimetry, and side effect profiles of 177Lu-PSMA-617 are discussed in this article. We also discuss results from prospective studies, major retrospective studies, meta-analyses, clinical trials, and mentioned major ongoing clinical trials on PRLT. We have also portrayed our own experiences and future perspectives on PRLT.

EXPERT OPINION

For PRLT, PSMA-617 and PSMA-I&T molecules have revolutionized the theranostic approach in the management of advanced prostate cancer, with solid backing from several published articles showing favorable outcomes and an excellent safety profile of 177Lu-PSMA-617. Improvement in quality of life and survival was seen in the majority of mCRPC patients after 177Lu-PSMA-617 PRLT. Patients with good performance status, asymptomatic, only lymph node metastases, high PSMA expressing lesions, and no discordant FDG avid lesions have a longer survival after 177Lu-PSMA-617 PRLT than patients with poor performance status, symptomatic, hepatic, brain, and skeletal metastases, discordant PSMA, and FDG-avid lesions. Docetaxel and cabazitaxel are approved treatments for mCRPC patients. 177Lu-PSMA-617 is approved as a third-line systemic treatment for mCRPC patients with failure to respond to androgen receptor pathway inhibitors and docetaxel therapy. PRLT is a safe and effective alternative to cabazitaxel (third-line systemic treatment), but it has a higher cost. 177Lu-PSMA-617 could be a more efficient therapeutic option for mCRPC patients as first-line or combined therapy, and it may be a useful therapeutic option for the treatment of metastatic hormone-sensitive prostate cancer (mHSPC) patients. Several clinical studies and clinical trials on PRLT are currently underway. In the future, the results of these trials will be helpful in evolving treatment strategies for prostate cancer patients.

Theragnostics in prostate cancer

Prostate-specific membrane antigen (PSMA) is a molecular target for both imaging diagnostics and therapeutics, i.e., a theragnostics target. There has been a growing body of evidence supporting PSMA theragnostics approaches in the management of prostate cancer (PCa) for tailored precision medicine. Tumor characterization through PSMA-ligand PET imaging is crucial for assessing the molecular signature and eligibility for PSMA radioligand therapy. Recent U.S. Food and Drug Administration (FDA) approval of two new drug applications for PSMA PET imaging contribute to reinforce PSMA as an oncologic blockbuster. Additionally, relevant progress in the PSMA treatment has been made in the last five years. [¹⁷⁷Lu]Lu-PSMA-617 radioligand therapy for patients with progressive PSMA-avid metastatic castration-resistant PCa (mCRPC) significantly increased overall survival and radiographic progression-free survival, according to the results of an international, prospective, open label, multicenter, randomized, phase III study (VISION trial). The objective of this comprehensive review is to highlight the recent advances in PCa theragnostics, focusing on actual clinical applications and future perspectives.