Radioimmunotherapy of B-cell lymphoma with radiolabelled anti-CD20 monoclonal antibodies

CD20 has proven to be an excellent target for the treatment of B-cell lymphoma, first for the chimeric monoclonal antibody rituximab (Rituxan™), and more recently for the radiolabelled antibodies Y-90 ibritumomab tiuxetan (Zevalin™) and I-131 tositumomab (Bexxar™). Radiation therapy effects are due to beta emissions with path lengths of 1–5 mm; gamma radiation emitted by I-131 is the only radiation safety issue for either product. Dose-limiting toxicity for both radiolabelled antibodies is reversible bone marrow suppression. They produce response rates of 70%–90% in low-grade and follicular lymphoma and 40%–50% in transformed low-grade or intermediate-grade lymphomas. Both products produce higher response rates than related unlabelled antibodies, and both are highly active in patients who are relatively resistant to rituximab-based therapy. Median duration of response to a single course of treatment is about 1 year with complete remission rates that last 2 years or longer in about 25% of patients. Clinical trials suggest that anti- CD20 radioimmunotherapy is superior to total body irradiation in patients undergoing stem cell supported therapy for B-cell lymphoma, and that it is a safe and efficacious modality when used as consolidation therapy following chemotherapy. Among cytotoxic treatment options, current evidence suggests that one course of anti-CD20 radioimmunotherapy is as efficacious as six to eight cycles of combination chemotherapy. A major question that persists is how effective these agents are in the setting of rituximab- refractory lymphoma. These products have been underutilised because of the complexity of treatment coordination and concerns regarding reimbursement

Noninvasive Monitoring of Mantle Cell Lymphoma by Immunoglobulin Gene Next-Generation Sequencing in a Phase 2 Study of Sequential Chemoradioimmunotherapy Followed by Autologous Stem-Cell Rescue

Minimal residual disease (MRD) monitoring has been used to identify early molecular relapse and predict clinical relapse in mantle cell lymphoma (MCL). Few published data exist in MCL on the performance of next-generation sequencing–based assay of immunoglobulin gene rearrangements for MRD assessment. In a prospective clinical trial (NCT01484093) with intensive induction chemotherapy and autologous stem-cell transplantation, posttreatment peripheral blood samples were collected from 16 MCL patients and analyzed with an earlier version of the Adaptive Biotechnologies MRD assay. Of the 7 patients whose disease remained in remission, the MRD test remained negative in 5 (71%). Of the 9 patients who experienced relapse, the MRD test was positive at least 3 months before relapse in 6 patients (67%) and positive at the time of relapse in 1 patient (11%). All patients with at least 2 positive MRD tests experienced relapse. The next-generation sequencing–based MRD assay identified early molecular relapse, and we observed more sensitivity in the cellular (circulating leukocytes) versus acellular (plasma cell-free DNA) compartment. This observation may be due to availability of tumor target or a limitation of the assay. Limited information exists in mantle cell lymphoma (MCL) on the performance of next-generation sequencing–based assay of immunoglobulin gene rearrangements for minimal residual disease (MRD) assessment. Posttreatment peripheral blood samples were collected from 16 MCL patients and analyzed with the Adaptive Biotechnologies MRD assay, which identified early molecular relapse. We observed more sensitivity in the cellular versus acellular compartment