Prostate cancer is the most frequently diagnosed malignant tumour in men worldwide. To treat this condition, prognostic markers to distinguish indolent from aggressive disease, and biomarkers for metastatic forms are needed. From a pathologist's perspective, despite the plethora of emerging biomarkers, none to date has made its way into clinical practice. The need for prognostic and predictive markers following histological evaluation remains. This overview of some putative immunohistochemical and genetic markers reveals the pitfalls of biomarker research, notably verifiability, validity and interlaboratory comparison. Meta-analyses and extensive cooperation between pathology departments are a sine qua non. Codes of Best Practice such as the REMARK guidelines have been advocated as a path forward. Currently, the most widely used and validated prognostic marker remains the Gleason score. Ki67 along with PTEN are the most promising prognostic markers.

• Keywords
• Gleason score, immunohistochemistry, prognostic and predictive markers, prostate adenocarcinoma, prostate biopsy, radical prostatectomy,
• MeSH
• Ki-67 Antigen metabolism   MeSH
• PTEN Phosphohydrolase metabolism   MeSH
• Humans MeSH
• Biomarkers, Tumor * metabolism   MeSH
• Prostatic Neoplasms * pathology   diagnosis   genetics   MeSH
• Pathologists MeSH
• Prognosis MeSH
• Neoplasm Grading MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Ki-67 Antigen MeSH
• PTEN Phosphohydrolase MeSH
• Biomarkers, Tumor * MeSH
• PTEN protein, human MeSH Browser

BACKGROUND: Targeted alpha therapy represents an advanced and rapidly evolving form of precision cancer treatment with increasing importance in recent years. The alpha-emitter 225Ac plays a key role in this clinical development due to its attractive physical and chemical properties. In this context, the macropa chelator has favorable characteristics in terms of labeling conditions and complex stability, making its derivatives exceptionally appealing for 225Ac-labeling of heat-sensitive biomolecules. However, preclinical evaluation of such 225Ac-containing molecules and comprehensive assessment of their pharmacokinetics, dosimetry and radiobiology necessitate a suitable diagnostic counterpart. Due to its attractive radiation properties, 133La represents an adequate positron-emitting radionuclide to form a matched pair with 225Ac for macropa-based radiopharmaceuticals. Herein, we describe the preparation and radiopharmacological characterization of macropa-functionalized, 133La/225Ac-labeled single-domain antibodies (sdAbs) targeting the epidermal growth factor receptor (EGFR) to demonstrate the general suitability of this theranostic pair of radionuclides. RESULTS: The synthesis of a clickable, bicyclononyne-modified macropa chelator and its site-specific conjugation to azide-modified, monovalent and biparatopic sdAbs is presented. Subsequent labeling at room temperature (rt) for 15 min resulted in molar activities of 30 MBq/nmol for 133La and 0.5 MBq/nmol for 225Ac, respectively. In vitro studies using the 133La-labeled sdAbs revealed comparable binding characteristics, but an enhanced cellular internalization of the biparatopic variant compared to its monovalent counterparts. This increased uptake consequently resulted in higher cytotoxicity of the 225Ac-labeled biparatopic conjugate. In vivo PET imaging of the 133La-labeled conjugates indicated comparable uptake and retention of the mono- and biparatopic variants in liver and kidneys, with the former showing slightly higher tumor accumulation. Ex vivo biodistribution studies conducted with 225Ac-labeled conjugates largely confirmed the findings obtained by PET imaging, albeit with a marginally higher tumor accumulation of the biparatopic 225Ac-radioimmunoconjugate. Final histological examinations of tumor and kidney tissues showed DNA damage in the renal cortex of the 225Ac-radioimmunoconjugate-treated mice, but no differences in the number of γ-H2AX-positive cells in the corresponding tumor tissues could be detected. CONCLUSIONS: We present a comprehensive study on the theranostic application of 133La and 225Ac for antibody-based biomolecules and lay the foundation for the future application of this matched pair of radionuclides towards labeling of heat-sensitive, macropa-functionalized radiopharmaceuticals in general. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s41181-025-00354-7.

• Keywords
• 133La, 225Ac, Biodistribution, Macropa, Pharmacokinetics, Positron emission tomography, Single-domain antibody, Targeted alpha therapy TAT, Theranostics,
• Publication type
• Journal Article MeSH

The tumor suppressor gene NKX3.1 and the LPL gene are located in close proximity on chromosome 8, and their deletion has been reported in multiple studies. However, the significance of LPL loss may be misinterpreted due to its co-deletion with NKX3.1, a well-established event in prostate carcinogenesis. This study investigates whether LPL deletion represents a biologically relevant event or occurs merely as a bystander to NKX3.1 loss. We analyzed 28 formalin-fixed paraffin-embedded prostate cancer samples with confirmed LPL deletion and 28 without. Immunohistochemical staining was performed, and previously published whole-genome sequencing data from 103 prostate cancer patients were reanalyzed. Deletion of the 8p21.3 region was associated with higher Gleason grade groups. While NKX3.1 expression was significantly reduced in prostate cancer compared to benign prostatic hyperplasia, LPL protein expression showed no significant difference between cancerous and benign tissue, nor was it affected by the 8p21.3 deletion status. Copy number analysis confirmed the co-deletion of NKX3.1 and LPL in 54 patients. Notably, NKX3.1 loss without accompanying LPL deletion was observed in eight additional cases. These findings suggest that LPL deletion is a passenger event secondary to NKX3.1 loss and underscore the importance of cautious interpretation of cytogenetic findings involving the LPL locus.

• Keywords
• FISH, LPL, NKX3.1, immunohistochemistry, prostate cancer, whole-genome sequencing,
• MeSH
• Gene Deletion * MeSH
• Homeodomain Proteins * genetics   metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Prostatic Neoplasms * genetics   pathology   metabolism   MeSH
• Disease Progression MeSH
• Gene Expression Regulation, Neoplastic MeSH
• Aged MeSH
• Transcription Factors * genetics   metabolism   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Homeodomain Proteins * MeSH
• NKX3-1 protein, human MeSH Browser
• Transcription Factors * MeSH

Despite improving diagnostic possibilities, the incidence of prostate cancer is increasing, but we are not able to reduce the mortality rate. While PSA, 4K score, PCA3 and other urinary markers, ExoDX, SelectMDX, Confirm MDx or MiPS tests are used to identify potential prostate cancer carriers, Decipher, Prolaris or Oncotype DX tests are used to assess the aggressiveness of proven cancer in order to stratify patients for early or delayed treatment. More modern forms of treatment for advanced disease include second-generation antiandrogens and PARP inhibitors. By assessing genetic mutations (e.g. BRCA1, BRCA2 genes, single nucleotide polymorphism) or the presence of splice variants of the androgen receptor (ARV7), we are able to identify patients in whom the planned treatment may be expected to be ineffective and thus choose other treatment modalities. In the present review article, we offer a comprehensive overview of current diagnostic tests that find application in the diagnosis of early and advanced prostate cancer.

• Keywords
• biomarker, cancer, prognosis, prostate, test, treatment,
• Publication type
• Journal Article MeSH
• Review MeSH

Rationale: Small 225Ac-labeled prostate-specific membrane antigen (PSMA)-targeted radioconjugates have been described for targeted alpha therapy of metastatic castration-resistant prostate cancer. Transient binding to serum albumin as a highly abundant, inherent transport protein represents a commonly applied strategy to modulate the tissue distribution profile of such low-molecular-weight radiotherapeutics and to enhance radioactivity uptake into tumor lesions with the ultimate objective of improved therapeutic outcome. Methods: Two ligands mcp-M-alb-PSMA and mcp-D-alb-PSMA were synthesized by combining a macropa-derived chelator with either one or two lysine-ureido-glutamate-based PSMA- and 4-(p-iodophenyl)butyrate albumin-binding entities using multistep peptide-coupling chemistry. Both compounds were labeled with [225Ac]Ac3+ under mild conditions and their reversible binding to serum albumin was analyzed by an ultrafiltration assay as well as microscale thermophoresis measurements. Saturation binding studies and clonogenic survival assays using PSMA-expressing LNCaP cells were performed to evaluate PSMA-mediated cell binding and to assess the cytotoxic potency of the novel radioconjugates [225Ac]Ac-mcp-M-alb-PSMA and [225Ac]Ac-mcp-D-alb-PSMA, respectively. Biodistributions of both 225Ac-radioconjugates were investigated using LNCaP tumor-bearing SCID mice. Histological examinations of selected organs were performed to analyze the occurrence of necrosis using H&E staining, DNA damage via γH2AX staining and proliferation via Ki67 expression in the tissue samples. Results: Enhanced binding to serum components in general and to human serum albumin in particular was revealed for [225Ac]Ac-mcp-M-alb-PSMA and [225Ac]Ac-mcp-D-alb-PSMA, respectively. Moreover, the novel derivatives are highly potent PSMA ligands as their KD values in the nanomolar range (23.38 and 11.56 nM) are comparable to the reference radioconjugates [225Ac]Ac-mcp-M-PSMA (30.83 nM) and [225Ac]Ac-mcp-D-PSMA (10.20 nM) without albumin binders. The clonogenic activity of LNCaP cells after treatment with the 225Ac-labeled ligands was affected in a dose- and time-dependent manner, whereas the bivalent radioconjugate [225Ac]Ac-mcp-D-alb-PSMA has a stronger impact on the clonogenic cell survival than its monovalent counterpart [225Ac]Ac-mcp-M-alb-PSMA. Biodistribution studies performed in LNCaP tumor xenografts showed prolonged blood circulation times for both albumin-binding radioconjugates and a substantially increased tumor uptake (46.04 ± 7.77 %ID/g for [225Ac]Ac-mcp-M-alb-PSMA at 128 h p.i. and 153.48 ± 37.76 %ID/g at 168 h p.i. for [225Ac]Ac-mcp-D-alb-PSMA) with favorable tumor-to-background ratios. Consequently, a clear histological indication of DNA damage was discovered in the tumor tissues, whereas DNA double-strand break formation in kidney and liver sections was less pronounced. Conclusion: The modification of the PSMA-based 225Ac-radioconjugates with one or two albumin-binding entities resulted in an improved radiopharmacological behavior including a greatly enhanced tumor accumulation combined with a rather low uptake in most non-targeted organs combined with a high excretion via the kidneys.

• Keywords
• Actinium, Albumin Binder, Macropa, PSMA, Targeted Alpha Therapy,
• MeSH
• Humans MeSH
• Ligands MeSH
• Mice, SCID MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Radiopharmaceuticals * pharmacokinetics   MeSH
• Serum Albumin * MeSH
• Tissue Distribution MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Actinium-225 MeSH Browser
• Ligands MeSH
• Radiopharmaceuticals * MeSH
• Serum Albumin * MeSH