A Single Dose of Novel PSMA-Targeting Radiopharmaceutical Agent [177Lu]Ludotadipep for Patients with Metastatic Castration-Resistant Prostate Cancer: Phase I Clinical Trial

Adverse reactions to therapeutic radiopharmaceuticals

Radiopharmaceuticals are drugs used in treatment or diagnosis that contain a radioactive part, usually a pharmaceutical part in their structure. Adverse drug reactions are harmful and unexpected responses that occur when administered at normal doses. Although radiopharmaceuticals are regarded as safe medical products, adverse reactions should not be ignored. More serious adverse reactions such as myelosuppression, pleural effusion, and death may develop in therapeutic radiopharmaceuticals due to their use at higher doses than those used in diagnosis. Therefore, monitoring adverse reactions and reporting them to health authorities is important. This review aims to provide information about adverse reactions that may be related to radiopharmaceuticals used in treatment.

Description of FDG and Prostate-Specific Membrane Antigen PET/CT Findings in Korean Patients With Advanced Metastatic Castration-Resistant Prostate Cancer

OBJECTIVE

We aimed to describe the [18F]fluorodeoxyglucose (FDG) and prostate-specific membrane antigen (PSMA) PET/CT findings in Korean men with advanced metastatic castration-resistant prostate cancer (mCRPC).

MATERIALS AND METHODS

The results of paired FDG and PSMA PET/CT examinations performed in 42 consecutive men with prostate cancer for treatment planning after failure of anti-androgen therapy and chemotherapy were studied. Tumor lesions with FDG or PSMA uptake intensity higher than that of the liver on visual review were considered positive and noted per patient and tumor site (prostate bed, lymph node, bone, and visceral organ). The presence of unequivocally discordant FDG and PSMA uptake patterns in tumor lesions was assessed. Patients were grouped according to the total tumor volume as seen on each PET/CT scan, and the clinical findings between the patient groups were compared using the Mann-Whitney U test.

RESULTS

On patient-based analysis, the image findings were PSMA+/FDG- in 2 patients, PSMA-/FDG+ in one, and PSMA+/FDG+ in 39 patients. On site-based analysis, the discordance (PSMA+/FDG- or PSMA-/FDG+) rate was 9.5% (4/42) for prostate/bed, 11.9% (5/42) for lymph nodes, 9.5% (4/42) for bones, and 11.9% (5/42) for visceral organs. FDG uptake was higher than PSMA uptake in at least one tumor site in 54.8% (23/42) of patients. Patients with greater total tumor volume on FDG PET/CT than that on PSMA PET/CT ("FDG-dominant pattern") accounted for 28.6% (12/42), and they had significantly shorter time from diagnosis (median 25 months vs. 62 months, P = 0.049), and higher aspartate aminotransferase (median 28.5 vs. 22.5, P = 0.027) and lactate dehydrogenase (median 341.5 vs. 224.5, P = 0.010) levels.

CONCLUSION

Most patients with advanced mCRPC had tumors with positive findings on both FDG and PSMA PET/CT. However, the uptake patterns varied; 54.8% of the patients had tumor(s) with FDG uptake greater than PSMA uptake, and FDG-dominant pattern was noted in 28.6% of the patients.

New Drugs for Targeted Radionuclide Therapy in Metastatic Prostate Cancer

Metastatic prostate cancer is a frequent and fatal disease. Targeted radionuclide therapy (TRT) has become a readily available therapeutic option since the approval of [177Lu]Lu-PSMA-617. Various molecules are currently being studied for TRT in prostate cancer. We review various combinations of isotopes and vectors being used to target prostate cancer cells and optimize pharmacokinetics. Promising innovations include chemical modifications to improve biodistribution, identification of new targets, and the use of novel radioisotopes such as α emitters. PATIENT SUMMARY: Our mini review summarizes research on targeted radioactive drugs for treatment of metastatic prostate cancer. Several promising radioactive pharmaceuticals are being evaluated in clinical trials, but more studies are necessary before these can be used in routine clinical practice.

Current clinical application of lutetium‑177 in solid tumors (Review)

Radionuclide-based therapy represents a novel treatment regimen for tumors. Among these therapies, lutetium-177 (177Lu) has gained significant attention due to its stability and safety, as well as its ability to emit both γ and β rays, allowing for both imaging with single photon emission computed tomography and tumor treatment. As a result, 177Lu can be used for both diagnosis and treatment for diseases such as prostatic and gastric cancer. Therefore, based on the available data, the present review provides a brief overview of the clinical applications of 177Lu-targeted radionuclide therapy in metastatic prostate cancer, neuroendocrine tumors and other types of solid tumors, and highlights the current therapeutic effect, reduction in damage to normal tissues and future research directions, including the development of new nuclides and the application of more nuclides in different tumors. In the future, such treatments could be used in more tumors.

Dosimetric Analysis of a Phase I Study of PSMA-Targeting Radiopharmaceutical Therapy With [177Lu]Ludotadipep in Patients With Metastatic Castration-Resistant Prostate Cancer

OBJECTIVE

177Lutetium [Lu] Ludotadipep is a novel prostate-specific membrane antigen targeting therapeutic agent with an albumin motif added to increase uptake in the tumors. We assessed the biodistribution and dosimetry of [177Lu]Ludotadipep in patients with metastatic castration-resistant prostate cancer (mCRPC).

MATERIALS AND METHODS

Data from 25 patients (median age, 73 years; range, 60-90) with mCRPC from a phase I study with activity escalation design of single administration of [177Lu]Ludotadipep (1.85, 2.78, 3.70, 4.63, and 5.55 GBq) were assessed. Activity in the salivary glands, lungs, liver, kidneys, and spleen was estimated from whole-body scan and abdominal SPECT/CT images acquired at 2, 24, 48, 72, and 168 h after administration of [177Lu]Ludotadipep. Red marrow activity was calculated from blood samples obtained at 3, 10, 30, 60, and 180 min, and at 24, 48, and 72 h after administration. Organ- and tumor-based absorbed dose calculations were performed using IDAC-Dose 2.1.

RESULTS

Absorbed dose coefficient (mean ± standard deviation) of normal organs was 1.17 ± 0.81 Gy/GBq for salivary glands, 0.05 ± 0.02 Gy/GBq for lungs, 0.14 ± 0.06 Gy/GBq for liver, 0.77 ± 0.28 Gy/GBq for kidneys, 0.12 ± 0.06 Gy/GBq for spleen, and 0.07 ± 0.02 Gy/GBq for red marrow. The absorbed dose coefficient of the tumors was 10.43 ± 7.77 Gy/GBq.

CONCLUSION

[177Lu]Ludotadipep is expected to be safe at the dose of 3.7 GBq times 6 cycles planned for a phase II clinical trial with kidneys and bone marrow being the critical organs, and shows a high tumor absorbed dose.

PSMA Radioligand Therapy in Prostate Cancer: Where Are We and Where Are We Heading?

ABSTRACT

Diagnosis and treatment of prostate cancer are complex and very challenging, being a major health care burden. The efficacy of radioligand therapy with prostate-specific membrane antigen agents has been proven beneficial in certain clinical indications. In this review, we describe management of prostate cancer patients according to current guidelines, especially focusing on the available clinical evidence for prostate-specific membrane antigen radioligand therapy.

Molecular heterogeneity in prostate cancer and the role of targeted therapy

Data collected from large-scale studies has shown that the incidence of prostate cancer globally is on the rise, which could be attributed to an overall increase in lifespan. So, the question is how has modern science with all its new technologies and clinical breakthroughs mitigated or managed this disease? The answer is not a simple one as prostate cancer exhibits various subtypes, each with its unique characteristics or signatures which creates challenges in treatment. To understand the complexity of prostate cancer these signatures must be deciphered. Molecular studies of prostate cancer samples have identified certain genetic and epigenetic alterations, which are instrumental in tumorigenesis. Some of these candidates include the androgen receptor (AR), various oncogenes, tumor suppressor genes, and the tumor microenvironment, which serve as major drivers that lead to cancer progression. These aberrant genes and their products can give an insight into prostate cancer development and progression by acting as potent markers to guide future therapeutic approaches. Thus, understanding the complexity of prostate cancer is crucial for targeting specific markers and tailoring treatments accordingly.

Evaluation of PSMA target diagnostic PET tracers for therapeutic monitoring of [177Lu]ludotadipep of prostate cancer: Screening of PSMA target efficiency and biodistribution using [18F]DCFPyL and [68Ga]PSMA-11

We have compared the similarity of the in vivo distribution of the prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) imaging agents [¹⁸F]DCFPyL, [⁶⁸Ga]galdotadipep, and [⁶⁸Ga]PSMA-11. This study is designed for a further selection of a PSMA-targeted PET imaging agent for the therapeutic evaluation of [¹⁷⁷Lu]ludotadipep, our previously developed prostate-specific membrane antigen (PSMA)-targeted prostate cancer therapeutic radiopharmaceutical. In vitro cell uptake was performed to evaluate the affinity to PSMA using PSMA + PC3-PIP, and PSMA- PC3-flu was used for the study. MicroPET/CT 60 min dynamic imaging and biodistribution were performed at 1, 2, and 4 h after injection. Autoradiography and immunohistochemistry were performed to evaluate the PSMA + tumor target efficiency. In the microPET/CT image, [⁶⁸Ga]PSMA-11 showed the highest uptake in the kidney among all three compounds. [¹⁸F]DCFPyL and [⁶⁸Ga]PSMA-11 showed similar patterns of in vivo biodistribution and high tumor targeting efficiency, similar to those of[⁶⁸Ga]galdotadipep. All three agents showed high uptake in tumor tissue on autoradiography, and PSMA expression was confirmed by immunohistochemistry. Thus, [¹⁸F]DCFPyL or [⁶⁸Ga]PSMA-11 can be used as a PET imaging agent to monitor [¹⁷⁷Lu]ludotadipep therapy in prostate cancer patients.