Recent advances and large-scale use of hybrid imaging modalities like PET-CT have led to the necessity of improving nano-drug carriers that can facilitate both functional and metabolic screening in nuclear medicine applications. In this study, we focused on the evaluation of four potential imaging nanoparticle structures labelled with the ⁶⁸Ga positron emitter. For this purpose, we functionalized NHS-activated PEG-gold nanoparticles with ⁶⁸Ga-DOTA-Neuromedin B, ⁶⁸Ga-DOTA-PEG(4)-BBN(7-14), ⁶⁸Ga-DOTA-NT and ⁶⁸Ga-DOTA-Neuromedin N. In vitro binding kinetics and specific binding to human HT-29 colon carcinoma cells and DU-145 prostate carcinoma cells respectively were assessed, over 75% retention being obtained in the case of ⁶⁸Ga-DOTA-PEG(4)-BBN(7-14)-AuNP in prostate tumour cells and over 50% in colon carcinoma cells. Biodistribution in NU/J mice highlighted a three-fold uptake increase in tumours at 30 min post-injection of ⁶⁸Ga-DOTA-NT-AuNP and ⁶⁸Ga-DOTA-PEG(4)-BBN(7-14)-AuNP compared to ⁶⁸Ga-DOTA-NT and ⁶⁸Ga-DOTA-PEG(4)-BBN(7-14) respectively, therewith fast distribution in prostate and colon tumours and minimum accumulation in non-targeted tissues.

The neurotensin is a tridecapeptide involved in the proliferation of colon cancer, the overexpression of neurotensin receptors occurring at an early stage development of many tumours. Targeting neurotensin receptors by using the same biological active molecule is an effective approach for both imaging quantification and treatment. The present work aimed to demonstrate the ability of radiolabelled neurotensin to specifically target colon cancer cells, and substantiate its usefulness in targeted imaging and radiotherapy, depending on the emission of the coupled radioisotope. Syntheses of ⁶⁸Ga–DOTA–NT and ¹⁷⁷Lu–DOTA–NT were developed to obtain a level of quality suitable for preclinical use with consistent high synthesis yields. Radiochemical purity meets the pharmaceutical requirements, and it is maintained 4 h for ⁶⁸Ga–DOTA–NT and 48 h for ¹⁷⁷Lu–DOTA–NT. Extensive in vitro studies were conducted to assess the uptake and retention of ⁶⁸Ga–DOTA–NT, the amount of non-specific binding of neurotensin and the effect of ¹⁷⁷Lu–DOTA–NT on HT–29 cells. In vivo biodistribution of ⁶⁸Ga–DOTA–NT revealed significant uptake at the tumour site, along with fast clearance evidenced by decreasing activity in kidneys and blood after 60 min p.i. ¹⁷⁷Lu–DOTA–NT exhibited similar uptake in the tumour, but also a significant uptake at 14 days p.i. in the bone marrow was reported. These results successfully demonstrated the potential of neurotensin to deliver imaging/therapeutic ⁶⁸Ga/¹⁷⁷Lu radioisotopes pair, but also the need for further evaluation of the possible radiotoxicity effects on the liver, kidneys or bone marrow.

On the verge of a theranostic approach to personalised medicine, copper-64 is one of the emerging radioisotopes in nuclear medicine due to its exploitable nuclear and biochemical characteristics. The increased demand for copper-64 for preclinical and clinical studies has prompted the development of production routes. This research aims to compare the (p,n) reaction on nickel-64 solid versus liquid targets and evaluate the effectiveness of [⁶⁴Cu]CuCl₂ solutions prepared by the two routes. As new treatments for neurotensin receptor-overexpressing tumours have developed, copper-64 was used to radiolabel Neurotensin (8-13) and Neuromedin N. High-quality [⁶⁴Cu]CuCl₂ solutions were prepared using ACSI TR-19 and IBA Cyclone Kiube cyclotrons. The radiochemical purity after post-irradiation processing reached 99% (LT) and 99.99% (ST), respectively. The irradiation of a solid target with 11.8 MeV protons and 150 μAh led to 704 ± 84 MBq/μA (17.6 ± 2.1 GBq/batch at EOB). At the end of the purification process (1 h, 90.90% activity yield), the solution for peptide radiolabelling had a radioactive concentration of 1340.4 ± 70.1 MBq/mL (n.d.c.). The irradiation of a liquid target with 16.9 MeV protons and 230 μAh resulted in 3.7 ± 0.2 GBq/batch at EOB, which corresponds to an experimental production yield of 6.89 GBq.cm3/(g.µA)_sat. Benefiting from a shorter purification process (40 min), the activity yielded 90.87%, while the radioactive concentration of the radiolabelling solution was lower (492 MBq/mL, n.d.c.). The [⁶⁴Cu]CuCl₂ solutions were successfully used for the radiolabelling of DOTA-NT(8-13) and DOTA-NN neuropeptides, resulting in a high RCP (>99%) and high molar activity (27.2 and 26.4 GBq/μmol for LT route compared to 45 and 52 GBq/μmol for ST route, respectively). The strong interaction between the [⁶⁴Cu]Cu-DOTA-NT(8-13) and the colon cancerous cell lines HT29 and HCT116 proved that the specificity for NTR had not been altered, as shown by the uptake and retention data.

Non-homologous end joining (NHEJ) is a critical DNA double-strand break (DSB) repair pathway that operates throughout the cell cycle to maintain the genomic stability of the cell. Unlike homologous recombination (HR), NHEJ is capable of repairing DSBs without the need for a homologous template, making it a rapid response mechanism, but potentially prone to errors. Central to NHEJ function and essential for the ligation through the recruitment and activation of additional repair factors, such as Artemis, XRCC4, and DNA ligase IV, is the DNA-dependent protein kinase (DNA-PK) complex. Dysregulation in the NHEJ pathway contributes to genomic instability, oncogenesis, and resistance to genotoxic therapies. Consequently, inhibitors of DNA-PK have emerged as promising therapeutic agents to sensitize tumor cells to radiation and DNA-damaging chemotherapeutics. Inhibiting the DNA-PK ability to recruit the protein complex needed for successful DSB repair promotes cell death through apoptosis or mitotic catastrophe. While inhibitors of DNA-PK can be used to enhance the effects of genotoxic therapies, the field still struggles to address critical problems: how to best exploit the differential DNA repair capacities among tumor subtypes, how to maximize radiosensitization of cancerous cells while sparing normal tissues, and how to translate preclinical studies into clinical benefits. Given that NHEJ constitutes the primary line of defense against radiation-induced damage, rapidly repairing the majority of double-strand breaks throughout the cell cycle, this review concentrates on targeting the DNA-PK complex, as the master regulator of this rapid-response mechanism, highlighting why its inhibition represents a strategic action to overcome intrinsic radioresistance. The implementation of DNA-PK inhibitors into medical practice can enable the stratification of oncologic patients into two categories, based on the tumors’ vulnerability to NHEJ disruptions. Thus, the therapeutic pathways of patients with NHEJ tumors could branch, combining traditional genotoxic therapies (radiation and DNA-damaging chemotherapeutics) with DNA-PK inhibitors to achieve an enhanced effect and improved survival outcomes.

Background: The ⁸⁹Zr radioisotope is increasingly vital in positron emission tomography (PET), especially immuno-PET, due to its long half-life of 78.4 h, allowing extended tracking of biological processes. This makes it particularly suitable for researching medicines with slow pharmacokinetics and enhances the precision of molecular imaging, especially in oncology. Despite zirconium’s potential for skeletal accumulation, effective chelation with agents like deferoxamine (DFO) enables high-resolution imaging of antigen-specific tumours, such as HER2-positive breast cancer, offering insights into tumour biology and treatment response. Methods: ⁸⁹Zr was produced at the ACSI TR-19 cyclotron via ⁸⁹Y(p,n)⁸⁹Zr reaction. Natural yttrium foils (250 μm) were irradiated with 12.9 MeV protons on target, with 100 μA·h. An HER2-targeting affibody was synthesized and conjugated with p-NCS-Bz-DFO (1:4 mass ratio) at 37 °C for 60 min (pH 9.2 ± 0.2), then purified on a PD-10 column. Radiolabelling was performed with [⁸⁹Zr]Zr-oxalate at pH ranging from 7.0 to 9.0, with concentrations from 110 to 460 MBq/mL. Results: Final activity reached 2.95 ± 0.31 GBq/batch (EOB corrected), with ≥ 99.9% radionuclide and ≥95% radiochemical purities. The anti-HER2 affibody was successfully radiolabelled with ⁸⁹Zr, resulting in a radiochemical purity of over 85% with molar activity of 26.5 ± 4.4 and 11.45 MBq/nmol at pH 7.0–7.5. In vitro tests on BT-474 and MCF-7 cell lines confirmed high uptake in HER2-positive cells, validating specificity and stability. Conclusions: The successful synthesis and labelling of the [⁸⁹Zr]Zr-p-NCS-Bz-DFO-anti-HER2 affibody are promising achievements for its further application in targeted immuno-PET imaging for HER2-positive malignancies. Further in vivo studies are needed to support its clinical translation.

NHEJ is one of the preferred DNA-damage repairing mechanisms for human cells, due to its rapid onset and activity throughout the cell cycle. It is, nevertheless, error prone and highly relevant in numerous oncological malignancies. In the recent years, it gained a lot of attention as a target either for cancer treatment or synergetic strategies, as pharmacological- and radio-sensitization approaches. This study evaluated the genotoxicity and radiosensitization potential of three DNA-PK inhibitors (PIK-75, M3814, and CC-115) in breast cancer by comparing MDA-MB-231 (NHEJ reliant) and MCF-7 (NHEJ and HR reliant) cell lines. Cells were preincubated with the DNA-PK inhibitors, using four different concentrations either in monotherapy or in combination with a DNA damage-inducer (doxorubicin or [64Cu]CuCl2). Viability was measured by MTS assays at 24, 48, and 72 h, while the DNA damage by γH2AX and flow cytometry. DNA-PK blockade preferentially sensitized NHEJ-reliant breast cancer cells to doxorubicin and 64Cu effect. Combination treatments generally reduced viability relative to inhibitor’s monotherapy, with clearer concentration dependence and stronger effects in MDA-MB-231. In the case of [64Cu]CuCl2 alone, MDA-MB-231 viability was reduced to 70–75% at 24 h, whereas several inhibitor combinations reduced it further; MCF-7 showed weaker or inconsistent potentiation. Delayed cytotoxicity was most obvious at 72 h, showing persistence of unrepaired DNA damage after DNA-PK inhibition. Overall, the results highlight the potential of exploiting repair-pathway dependence to improve targeted radiotherapy in breast cancer.