Page 16 - ARNM-2-4

Advances in Radiotherapy
& Nuclear Medicine Radionuclide-carrying liposomes

11. Studies of therapeutic applications of to fulfill. They have many promising applications in
radionuclide-containing liposomes radiology, nuclear medicine diagnostics, and radionuclide
therapy. The ultimate goal for liposomal therapy is the
At present, 186 Re-labeled liposomes, known as mitigation of toxic side effects and increased accumulation
186 Re-obisbemeda, have completed Phase I clinical trials for of chosen substances to targeted sites in a selective manner.
recurrent glioblastoma through CED and are currently in Different methods of radiolabeling can be used to attach
46
Phase II trials. In Phase I studies, much higher radiation various types of radionuclides to liposomes for both
doses were safely delivered to the glioblastoma (~300 Gy), diagnostic and therapeutic purposes. The EPR effect with
versus standard external beam radiation therapy (~70 – liposomes gives them an intrinsic advantage for passive
80 Gy). Phillips et al. described how future studies using targeting of tumor regions. Additional methods of active
43
nuclear imaging to monitor the performance of CED will targeting can be taken to intensify selectivity. A significant
be crucial for developing safe CED-administered liposome obstacle for liposomal drug delivery is posed by uptake
radionuclide therapy. by the MPS system; however, if uptake in the liver, spleen,

186 Re-obisbemeda is also currently in a Phase I study for and bone marrow can be avoided, uptake of liposomes by
the treatment of leptomeningeal metastasis that commonly macrophages within the tumor or in an infectious site can
occurs in patients with breast cancer, prostate cancer, and be an advantage. While treatment using liposomes comes
brain cancer. In this treatment, the 186 Re-obisbemeda with complications that should be carefully considered,
47
is administered into an Ommaya reservoir, which they have already made a positive impact on patients’ lives
connects to the central spinal fluid (CSF), allowing through FDA-approved liposomal drugs. The imaging
the 186 Re-obisbemeda to spread throughout the brain of radiolabeled liposomes offers great potential to non-
and spinal CSF to deliver high doses of radiation to the invasively track the delivery of drugs to targeted sites in
leptomeningeal metastasis. the body. In addition, liposomes carrying therapeutic
Chang et al. have shown the therapeutic potential of radionuclides have great potential for cancer therapy
48
intravenously injected Re-liposomes for the treatment of and are currently used in clinical trials for recurrent
188
a variety of tumors including colorectal cancer, head and glioblastoma and leptomeningeal metastasis.
neck cancer, and ovarian cancer. Li et al. have also used
48
19
peptide-targeted liposomes to treat cervical cancer with Acknowledgments
iodine-131-containing liposomes. 19 The authors thank Jonathan Sumner of UT Health San
Antonio Creative Media Services for his help formatting
12. Future steps and considerations the images in the article. The authors would also like to
While liposomes have shown promising qualities as thank Dr. Jayanta K. Chaudhuri for technical support
nanocapsules for increasing the efficiency of cancer during the writing of this article.
chemotherapy and radionuclide-based radiotherapy, some
challenges remain. The prominent uptake of liposomes by Funding
the MPS following intravenous delivery limits the delivery None.
of treatment to the cancerous area. It can also cause damage
to sites of uptake in the MPS, such as the bone marrow, Conflict of interest
in addition to the liver and spleen. The high MPS uptake The authors declare they have no competing interests.
of liposomes including those coated with PEG is one of
the most significant obstacles posed by liposomal drug Author contributions
delivery, and it should be an area of focus for researchers to
find ways to avoid clearance of liposomes by the MPS. The Conceptualization: Rashmi Basu
development of techniques such as PEGylation is a step in Visualization: Rashmi Basu
the right direction. Other approaches to avoid uptake by Writing – original draft: Rashmi Basu, William T. Phillips
the MPS include delivery of radiotherapeutic liposomes Writing – review & editing: All authors
to body cavities and subcutaneously for trapping in lymph Ethics approval and consent to participate
nodes containing metastatic cancer cells. 26,49
Not applicable.
13. Conclusion
Consent for publication
Liposomes are very versatile structures that can be modified
in countless ways to suit the purpose they are intended Not applicable.

Volume 2 Issue 4 (2024) 8 doi: 10.36922/arnm.4373