Maximum-tolerated dose, toxicity, and efficacy of (131)I-Lym-1 antibody for fractionated radioimmunotherapy of non-Hodgkin's lymphoma.
OBJECTIVE
Lym-1, a monoclonal antibody that preferentially targets malignant lymphocytes, has induced remissions in patients with non-Hodgkin's lymphoma (NHL) when labeled with iodine 131 ((131)I). Based on the strategy of fractionating the total dose, this study was designed to define the maximum-tolerated dose (MTD) and efficacy of the first two, of a maximum of four, doses of (131)I-Lym-1 given 4 weeks apart. Additionally, toxicity and radiation dosimetry were assessed.


METHODS
Twenty patients with advanced NHL entered the study a total of 21 times. Thirteen (62%) of the 21 entries had diffuse large-cell histologies. All patients had disease resistant to standard therapy and had received a mean of four chemotherapy regimens. (131)I-Lym-1 was given after Lym-1 and (131)I was escalated in cohorts of patients from 40 to 100 mCi (1.5 to 3.7 GBq)/m2 body surface area.


RESULTS
Mean radiation dose to the bone marrow from body and blood (131)I was 0.34 (range, 0. 1 6 to 0.63) rad/mCi (0.09 mGy/MBq; range, 0.04 to 0.17 mGy/ MBq). Dose-limiting toxicity was grade 3 to 4 thrombocytopenia with an MTD of 100 mCi/m2 (3.7 GBq/m2) for each of the first two doses of (131)I-Lym-1 given 4 weeks apart. Nonhematologic toxicities did not exceed grade 2 except for one instance of grade 3 hypotension. Ten (71 %) of 14 entries who received at least two doses of (131)I-Lym-1 therapy and 11 (52%) of 21 total entries responded. Seven of the responses were complete, with a mean duration of 14 months. All three entries in the 100 mCi/m2 (3.7 MBq/m2) cohort had complete remissions (CRs). All responders had at least a partial remission (PR) after the first therapy dose of (131)I-Lym-1.


CONCLUSIONS
(131)I-Lym-1 induced durable remissions in patients with NHL resistant to chemotherapy and was associated with acceptable toxicity. The nonmyeloablative MTD for each of the first two doses of (131)I-Lym-1 was 100 mCi/m2 (total, 200 mCi/m2) (3.7 GBq/m2; total, 7.4 GBq/m2).
Department of Internal Medicine, University of California Davis Medical Center, Sacramento, USA. gldenardo@ucdavis.edu
G L
GL
DeNardo
S J
SJ
DeNardo
D S
DS
Goldstein
L A
LA
Kroger
K R
KR
Lamborn
N B
NB
Levy
J P
JP
McGahan
Q
Q
Salako
S
S
Shen
J P
JP
Lewis
D000328:Adult; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use*; D001803:Blood Transfusion; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000009:adverse effects / Q000627:therapeutic use*; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*; D008228:Lymphoma, Non-Hodgkin / Q000532:radiotherapy*; D008297:Male; D051379:Mice; D008875:Middle Aged; D009503:Neutropenia / Q000209:etiology / Q000628:therapy; D016499:Radioimmunotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D013921:Thrombocytopenia / Q000209:etiology / Q000628:therapy
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007457:Iodine Radioisotopes