scholarly journals Prostate-Specific Membrane Antigen (PSMA) Theranostics for Treatment of Oligometastatic Prostate Cancer

2021 ◽  
Vol 22 (22) ◽  
pp. 12095
Author(s):  
Kristin A. Plichta ◽  
Stephen A. Graves ◽  
John M. Buatti

Theranostics, a combination of therapy and diagnostics, is a field of personalized medicine involving the use of the same or similar radiopharmaceutical agents for the diagnosis and treatment of patients. Prostate-specific membrane antigen (PSMA) is a promising theranostic target for the treatment of prostate cancers. Diagnostic PSMA radiopharmaceuticals are currently used for staging and diagnosis of prostate cancers, and imaging can predict response to therapeutic PSMA radiopharmaceuticals. While mainly used in the setting of metastatic, castrate-resistant disease, clinical trials are investigating the use of PSMA-based therapy at earlier stages, including in hormone-sensitive or hormone-naïve prostate cancers, and in oligometastatic prostate cancers. This review explores the use of PSMA as a theranostic target and investigates the potential use of PSMA in earlier stage disease, including hormone-sensitive metastatic prostate cancer, and oligometastatic prostate cancer.

2021 ◽  
Vol 10 (5) ◽  
pp. 205846012110225
Author(s):  
Omer Aras ◽  
Stefan Harmsen ◽  
Richard Ting ◽  
Haluk B Sayman

Targeted radionuclide therapy has emerged as a promising and potentially curative strategy for high-grade prostate cancer. However, limited data are available on efficacy, quality of life, and pretherapeutic biomarkers. Here, we highlight the case of a patient with prostate-specific membrane antigen (PSMA)-positive metastatic castrate-resistant prostate cancer who displayed complete response to 225Ac-PSMA-617 after having been resistant to standard-of-care therapy, then initially partially responsive but later resistant to subsequent immunotherapy, and resistant to successive 177Lu-PSMA-617. In addition, the patient’s baseline germline mutation likely predisposed him to more aggressive disease.


2017 ◽  
Vol 35 (6_suppl) ◽  
pp. 213-213
Author(s):  
Benedikt Engels ◽  
Ozan Cem Guler ◽  
Cem Onal ◽  
Mark De Ridder

213 Background: Metastases-directed therapy by metastasectomy or radiotherapy (RT) might delay disease progression and postpone systemic treatment in patients with oligometastatic prostate cancer. Here, we evaluated retrospectively the efficacy and toxicity of 68Ga prostate-specific membrane antigen (PSMA) PET-CT guided radiotherapy (RT) in the treatment of oligometastatic prostate cancer. Methods: A total of 23 prostate cancer patients with biochemical relapse, of which 13 castration-sensitive and 10 castration-resistant, were treated with intensity-modulated and image-guided RT (IMRT-IGRT) on ≤ 3 metastases detected by 68Ga PSMA PET-CT. Androgen deprivation therapy was continued in castration-resistant patients. Local control (LC), progression-free survival (PFS) and overall survival (OS) were estimated with the Kaplan-Meier method. Results: A total of 38 metastases were treated. Involved sites were pelvic bone (n = 16), pelvic lymph nodes (n = 11), para-aortic lymph nodes (n = 6), ribs (n = 3) and vertebral body (n = 2). The median PSA prior to RT was 1.06 ng/ml (range 0.10 – 29.0 ng/ml). A median dose of 43.5 Gy (range, 30-64 Gy) was delivered by IMRT-IGRT in 12-27 fractions. At a median follow-up of 7 months (range, 2-17 months), 19 patients (83%) are in remission. Four patients (17%) developed distant recurrence. The actuarial 1-year LC, PFS and OS rates were 100%, 51% (95% CI 8-83%) and 100%. Castration-sensitive patients displayed a statistically significantly superior PFS on univariate analysis as compared to castration-resistant patients (1-year PFS 67% vs 0%, p < 0.01). One patient experienced grade 2 acute gastro-intestinal toxicity. No grade 3 or more toxic events were observed. Conclusions: By providing optimal LC, low toxicity and a promising PFS in castration-sensitive patients, the current retrospective study illustrated that 68Ga PSMA PET-CT guided RT may be an attractive treatment option in patients with oligometastatic prostate cancer. Validation by randomized trials is eagerly awaited.


Author(s):  
Tanya B. Dorff ◽  
Stefano Fanti ◽  
Andrea Farolfi ◽  
Robert E. Reiter ◽  
Taylor Y. Sadun ◽  
...  

Prostate-specific membrane antigen (PSMA)–based imaging seeks to fill some critical gaps in prostate cancer staging and response assessment, and may select patients for treatment with radiolabeled PSMA conjugates. In biochemical recurrence, at prostate-specific antigen (PSA) levels as low as 0.2 ng/dL, 68Ga-PSMA imaging has demonstrated a 42% detection rate of occult metastatic disease, and detection has been greater than 95% when PSA levels are higher than 2 ng/dL. This may facilitate novel approaches, including salvage lymphadenectomy or metastasis-directed radiation therapy, in patients with oligometastatic disease. PSMA-based imaging has shown promise in evaluating treatment response in hormone-sensitive and castration-resistant disease; however, additional longitudinal assessment is needed given the heterogeneity in uptake changes after the initiation of androgen-deprivation therapy. Changes in uptake must be taken in context of RECIST measurements and other response parameters, given the potential for growth of PSMA-negative lesions and persistent uptake in treated bone lesions of uncertain significance. For selecting patients to receive PSMA-targeted radioconjugate therapy, standardized uptake value thresholds remain to be established. Nevertheless, preliminary data from 177Lu-PSMA theranostic trials have yielded PSA responses in up to 57% of patients, as well as pain relief and improved quality of life. Thrombocytopenia was the most common grade 3 or greater toxicity; however, grade 1 xerostomia occurred frequently and was cited as the most common reason for treatment discontinuation.


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