Optimization of the radiolabelling method for improved in vitro and in vivo stability of 90Y-albumin microspheres

Polydopamine-Coated Radiolabeled Microspheres for Combinatorial Radioembolization and Photothermal Cancer Therapy

Transarterial radioembolization (TARE) is a local radionuclide therapy and is successfully used in hepatocellular carcinoma (HCC) treatment. Radioactive microspheres have been widely studied for TARE. Preparation of ideal radioactive microspheres is significant for clinical research and patient treatment. In this study, we have designed a novel multifunctional microsphere, i.e., polydopamine (PDA)-coated ¹⁷⁷Lu-radiolabeled silica microspheres (MS) denoted as ¹⁷⁷Lu-MS@PDA, which can be used for TARE and photothermal therapy (PTT). The radiostability of ¹⁷⁷Lu-MS@PDA was significantly improved by coating ¹⁷⁷Lu-MS with PDA. In addition, the coating of PDA makes microspheres have excellent photothermal performance. MicroSPECT/CT images showed that ¹⁷⁷Lu-MS@PDA was accurately embolized and remained in the tumor during the observation time. At the time, it also showed that ¹⁷⁷Lu-MS@PDA was very stable in vivo. Furthermore, the anti-tumor results demonstrated that TARE combined with PTT of ¹⁷⁷Lu-MS@PDA can significantly inhibit tumor growth without obvious side effects. ¹⁷⁷Lu-MS@PDA holds great potential as a promising radioactive microsphere for HCC.

Microspheres as a Carrier System for Therapeutic Embolization Procedures: Achievements and Advances

The targeted delivery of anti-cancer drugs and isotopes is one of the most pursued goals in anti-cancer therapy. One of the prime examples of such an application is the intra-arterial injection of microspheres containing cytostatic drugs or radioisotopes during hepatic embolization procedures. Therapy based on the application of microspheres revolves around vascular occlusion, complemented with local therapy in the form of trans-arterial chemoembolization (TACE) or radioembolization (TARE). The broadest implementation of these embolization strategies currently lies within the treatment of untreatable hepatocellular cancer (HCC) and metastatic colorectal cancer. This review aims to describe the state-of-the-art TACE and TARE technologies investigated in the clinical setting for HCC and addresses current trials and new developments. In addition, chemical properties and advancements in microsphere carrier systems are evaluated, and possible improvements in embolization therapy based on the modification of and functionalization with therapeutical loads are explored.

177Lu-doxycycline as potential radiopharmaceutical: electrochemical characterization, radiolabeling, and biodistribution in tumor-bearing mice

PURPOSE

Recent studies with doxycycline as adjuvant therapy to conventional chemotherapy have shown promising results in cancer therapy. The current study aimed to examine the capability of ¹⁷⁷Lu-labeled tetracycline ligand, doxycycline hyclate, to use as an anticancer agent.

MATERIALS AND METHODS

Doxycycline was radiolabeled with beta-emitting radioisotope ¹⁷⁷Lu. Complex formation and its interaction with DNA were investigated electrochemically. Binding of ¹⁷⁷Lu-doxycycline to CT 26 cell line was done. Biodistribution of ¹⁷⁷Lu-doxycycline was examined in healthy Wistar rats and CT26 colon carcinoma tumor-bearing mice by i.v. and i.p. administration, respectively.

RESULTS

Doxycycline hyclate was successfully radiolabeled with ¹⁷⁷Lu in high radiolabeling yield (>99%). The radiolabeled complex was stable in vitro in saline and human serum over 72 h. Non-radioactive Lu-doxycycline complex formation was demonstrated electrochemically as well. Intercalative interactions of the doxycycline and Lu-doxycycline with DNA were proved using simultaneously spectrophotometric and electrochemical methods. The binding of the radiolabeled complex with plasma proteins was 4.0 ± 0.4%. The partition coefficient showed the lipophilic nature of the complex similar to the free ligand. The binding curve demonstrates binding from 0.1 nM concentrations of ¹⁷⁷Lu-doxycycline, with half-binding estimated ∼100 nM. Biodistribution studies of ¹⁷⁷Lu-doxycycline in CT26 colon tumor-bearing mice showed a satisfactory accumulation rate in the tumor (2.88 ± 0.85% ID/g) 3 h after intraperitoneal injection. Both the hepatobiliary system and the urinary system were prominent as excretory routes of the radiolabeled complex.

CONCLUSION

Considering obtained results, ¹⁷⁷Lu-doxycycline complex, due to its excellent electrochemical and biological characteristics, with emphasis on the binding ability to DNA via intercalative interaction as well as significant accumulation in the tumor, is suitable for further in vivo studies to investigate its potential use in cancer treatment.