It has been said that "α-emitters are indispensable with regard to optimisation of strategies for tumour therapy".[4]
Advantages of alpha emitters
The primary advantage of
alpha particle (α) emitters over other types of radioactive sources is their very high
linear energy transfer (LET) and
relative biological effectiveness (RBE).[5]Beta particle (β) emitters such as
yttrium-90 can travel considerable distances beyond the immediate tissue before depositing their energy, while alpha particles deposit their energy in 70–100 μm long tracks.[6]
Alpha particles are more likely than other types of radiation to cause
double-strand breaks to DNA molecules, which is one of several effective causes of
cell death.[7][8]
Production
Some α emitting isotopes such as
225Ac and
213Bi are only available in limited quantities from
229Th decay, although
cyclotron production is feasible.[9][10][11] Among alpha-emitting radiometals according to availability, chelation chemistry, and half-life,
212Pb is also a promising candidate for targeted alpha-therapy.[12][13]
The ARRONAX cyclotron can produce
211At by irradiation of
209Bi.[14][9]
Applications
Though many α-emitters exist, useful isotopes would have a sufficient energy to cause damage to cancer cells, and a
half-life that is long enough to provide a therapeutic
dose without remaining long enough to damage healthy tissue.
Immunotherapy
Several radionuclides have been studied for use in
immunotherapy. Though β-emitters are more popular, in part due to their availability, trials have taken place involving 225Ac, 211At, 212Pb and 213Bi.[9]
Peritoneal carcinomas
Treatment of peritoneal carcinomas has promising early results limited by availability of α-emitters compared to β-emitters.[4]
The short
path length of alpha particles in tissue, which makes them well suited to treatment of the above types of disease, is a negative when it comes to treatment of larger bodies of
solid tumour by intravenous injection.[20][21] Potential methods to solve this problem of delivery exist, such as direct intratumoral injection[22] and
anti-angiogenic drugs.[23][3] Limited treatment experience of low grade malignant
gliomas has shown possible efficacy.[24]
^Committee on State of the Science of Nuclear Medicine; National Research Council; Division on Earth and Life Studies; Institute of Medicine; Nuclear and Radiation Studies Board; Board on Health Sciences Policy (2007).
"Targeted Radionuclide Therapy". Advancing nuclear medicine through innovation. Washington, D.C.: National Academies Press.
doi:
10.17226/11985.
ISBN978-0-309-11067-9.
PMID20669430. {{
cite book}}: |last6= has generic name (
help)
^Baum, Richard P (2014). Therapeutic Nuclear Medicine. Heidelberg: Springer. p. 98.
ISBN9783540367192.
^Hodgkins, Paul S.; O'Neill, Peter; Stevens, David; Fairman, Micaela P. (December 1996). "The Severity of Alpha-Particle-Induced DNA Damage Is Revealed by Exposure to Cell-Free Extracts". Radiation Research. 146 (6): 660–7.
Bibcode:
1996RadR..146..660H.
doi:
10.2307/3579382.
JSTOR3579382.
PMID8955716.
^Huang, Chen-Yu; Pourgholami, Mohammad H.; Allen, Barry J. (November 2012). "Optimizing radioimmunoconjugate delivery in the treatment of solid tumor". Cancer Treatment Reviews. 38 (7): 854–860.
doi:
10.1016/j.ctrv.2011.12.005.
PMID22226242.
^Cordier, Dominik; Krolicki, Leszek; Morgenstern, Alfred; Merlo, Adrian (May 2016). "Targeted Radiolabeled Compounds in Glioma Therapy". Seminars in Nuclear Medicine. 46 (3): 243–249.
doi:
10.1053/j.semnuclmed.2016.01.009.
PMID27067505.