Application of the linear-quadratic model to radioimmunotherapy: Further support for the advantage of longer-lived radionuclides

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Journal of Nuclear Medicine

OSTI ID:114871

Howell, R W; Goddu, S M; Rao, D V ^[1]

---

1. Univ. of Medicine & Dentistry of New Jersey, Newark, NJ (United States)

Radioimmunotherapy (RIT), as it is currently practiced, delivers low doses to tumors primarily because of dose-limiting bone marrow toxicity. The biologic effectiveness of RIT depends on the total dose, dose rate and the fractionation schedule of the radiolabeled antibodies administered. An approach based on the linear-quadratic (:LQ) model, which is currently used in conventional radiotherapy, is advanced for treatment planning in RIT. This approach incorporates repair rates, radiosensitivity of the tissues, biologic half-lives of the antibodies, physical half-lives of the radionuclides, dose rates and total doses needed for a given biologically effective dose. The concept of a relative advantage factor (RAF) is introduced to quantify the therapeutic gain that can be realized by using longer-lived radionuclides instead of the shorter-lived counterparts currently in use. RAFs are calculated for different biologic and physical half-lives, and values as high as 3 to 5 can be attained when longer-lived radionuclides are used. The RAFs predicted by the LQ model reaffirm the authors` earlier conclusion based on the time-dose-fractionation approach that relatively long-lived radionuclides coupled to monoclonal antibodies are indeed more likely to deliver therapeutically effective doses to tumors. Several radionuclides are evaluated in this context. The authors maintain that {sup 32}P is the most promising isotope and the optimal physical half-life is about two to three times the biologic clearance half-life of the antibodies in the tumor. 21 refs., 4 figs., 3 tabs.

• OSTI ID: 114871
• Journal Information: Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: 11 Vol. 35; ISSN 0161-5505; ISSN JNMEAQ
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
DOSIMETRY
PHOSPHORUS 32
RADIATION DOSES
RADIOIMMUNOTHERAPY