Extended Interval Dosing of Anti-CD20 Therapies: Benefits, Risks, and Real-World Experience

In this episode titled "Extended Interval Dosing of Anti-CD20 Therapies: Benefits, Risks, and Real-World Experience," moderator Dr. Mitzi Joi Williams introduces the concept of extended interval dosing (EID): rather than dosing on a fixed six-month or monthly schedule, could practitioners dose less frequently while maintaining efficacy — whether for cost, safety, or patient preference?

Dr. Krieger sees EID as reasonable in specific scenarios: when infection risk or other adverse events begin to emerge, not as a blanket practice change. He notes that B-cell recovery lags far behind the dosing interval — B cells remain depleted well beyond six months after an infusion, and disease activity does not necessarily return even when B cells reconstitute. However, he cautions that there are no clinical trial data for EID; available evidence from lower-dose phase II studies suggests "less may work," while higher-dose studies showed no added benefit, supporting theoretical room to extend. He emphasizes that this reasoning alone doesn't confirm that EID reduces infection risk.

Dr. Greenberg is more skeptical, noting that without a reliable biomarker to track B-cell depletion and disease suppression at the individual level, extending intervals at a population scale is unjustifiable. He mentions an NIH-funded study testing immune remodeling after prolonged B-cell depletion, the results of which could inform future EID approaches.

Dr. Bove describes a middle ground: a small subset of patients in her practice, often older, follow individualized EID protocols monitoring CD19 counts to guide re-dosing timing. She acknowledges EID may be particularly valuable in low- and middle-income countries where rituximab access is the primary option and dose reduction enables more patients to be treated.

In the next episode, "The MS 'Wearing-Off' Phenomenon: Separating Symptom Burden from Immunological Change," the panel discusses what patients describe as a worsening of symptoms before their next dose — and how to manage it.