Effect of antilymphoma antibody, 131I-Lym-1, on peripheral blood lymphocytes in patients with non-Hodgkin's lymphoma.

Anti-CD20 monoclonal antibodies (mAbs), unlabeled rituximab (Rituxan, Biogen Idec Inc., Cambridge, MA; and Genentech Inc., South San Francisco, CA) or radiolabeled 90Y-ibritumomab (Zevalin, Biogen Idec Inc., Cambridge, MA) and 131I-tositumomab (Bexxar; Glaxo Smith Kline, Research Triangle Park, NC), have proven to be effective therapy for non-Hodgkin's lymphoma (NHL), but also induce immediate and persistent decreases in normal peripheral blood lymphocytes (PBLs). Lym-1, a mAb that selectively targets malignant lymphocytes, also has induced therapeutic responses and prolonged survival in patients with NHL when labeled with iodine-131 (131I). We have retrospectively examined its effect on PBLs in 41 NHL patients that had received 131I-Lym-1 therapy. Absolute lymphocyte counts (ALCs) were evaluated before and after the first and last 131I-Lym-1 infusion. Modest decreases in PBLs were observed in most of the patients. Using strict criteria to define recovery, time to recovery was determined for 19 patients, with the remainder censored because of insufficient follow-up (median follow up for censored patients: 22 days). Using Kaplan-Meier estimates, it would be predicted that 31% of patients would recover by 28 days and that median time to recovery would be 44 days after the last 131I-Lym-1 infusion. No predictors were found for time to recovery, considering such factors as the administered Lym-1 or 131I dose, spleen volume, or radiation doses to the body, marrow, or spleen. The data suggest that the effect of 131I-Lym-1 on ALC is the result of a nonspecific radiation effect, rather than a specific Lym-1 mAb effect. The shorter time required for ALC recovery after 131I-Lym-1 when compared to that reported for anti-CD20 mAbs, whether radiolabeled or otherwise, is probably related to differing mechanisms for lymphocytotoxicity and lesser Lym-1 antigenic density on normal B-lymphocytes.

High-dose radioimmunotherapy combined with fixed, low-dose paclitaxel in metastatic prostate and breast cancer by using a MUC-1 monoclonal antibody, m170, linked to indium-111/yttrium-90 via a cathepsin cleavable linker with cyclosporine to prevent human anti-mouse antibody.

PURPOSE: Although radioimmunotherapy alone is effective in lymphoma, its application to solid tumors will likely require a combined modality approach. In these phase I studies, paclitaxel was combined with radioimmunotherapy in patients with metastatic hormone-refractory prostate cancer or advanced breast cancer. EXPERIMENTAL DESIGN: Patients were imaged with indium-111 (111In)-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-peptide-m170. One week later, yttrium-90 (90Y)-m170 was infused (12 mCi/m2 for prostate cancer and 22 mCi/m2 for breast cancer). Initial cohorts received radioimmunotherapy alone. Subsequent cohorts received radioimmunotherapy followed 48 hours later by paclitaxel (75 mg/m2). Cyclosporine was given to prevent development of human anti-mouse antibody. RESULTS: Bone and soft tissue metastases were targeted by 111In-m170 in 15 of the 16 patients imaged. Three prostate cancer patients treated with radioimmunotherapy alone had no grade 3 or 4 toxicity. With radioimmunotherapy and paclitaxel, two of three prostate cancer patients developed transient grade 4 neutropenia. Four breast cancer patients treated with radioimmunotherapy alone had grade 3 or 4 myelosuppression. With radioimmunotherapy and paclitaxel, both breast cancer patients developed grade 4 neutropenia. Three breast cancer patients required infusion of previously harvested peripheral blood stem cells because of neutropenic fever or bleeding. One patient in this trial developed human anti-mouse antibody in contrast to 12 of 17 patients in a prior trial using m170-radioimmunotherapy without cyclosporine. CONCLUSIONS: 111In/90Y-m170 targets prostate and breast cancer and can be combined with paclitaxel with toxicity limited to marrow suppression at the dose levels above. The maximum tolerated dose of radioimmunotherapy and fixed-dose paclitaxel with peripheral blood stem cell support has not been reached. Cyclosporine is effective in preventing human anti-mouse antibody, suggesting the feasibility of multidose, "fractionated" therapy that could enhance clinical response.