Do Not Add Epcoritamab to Continue R2 After Progression
After progression on rituximab-lenalidomide (R2) therapy, you should NOT simply add epcoritamab to continue the same regimen—instead, you should switch to an entirely different treatment approach. The patient has already demonstrated resistance to R2, and continuing the failed backbone while adding epcoritamab is not a validated strategy.
Why This Approach Is Wrong
The fundamental issue is that epcoritamab + R2 is studied and approved as a complete regimen initiated together from the start, not as a salvage add-on after R2 failure 1. The EPCORE FL-1 trial that established epcoritamab + R2 superiority enrolled patients who were starting a new line of therapy—not patients actively progressing on R2 1.
When a patient progresses on R2, they have demonstrated rituximab-refractory disease. The 2021 ESMO guidelines explicitly state that in rituximab-refractory cases or remissions lasting <6 months, you should switch to obinutuzumab-bendamustine (or other chemotherapy regimen) plus obinutuzumab maintenance 2.
What You Should Do Instead
For Relapsed/Refractory FL After ≥2 Prior Lines (Including Failed R2):
According to the most recent 2025 NCCN guidelines, approved options include 3:
CD3 × CD20 bispecific antibodies as monotherapy:
- Epcoritamab (approved for ≥2 prior therapies)
- Mosunetuzumab
CD19-directed CAR T-cell therapies:
- Axicabtagene ciloleucel
- Tisagenlecleucel
- Lisocabtagene maraleucel
BTK inhibitor-based combination:
- Zanubrutinib + obinutuzumab
Novel triple therapy (if starting fresh):
- Tafasitamab + lenalidomide + rituximab (the inMIND study showed this improved PFS compared to R2 alone, but this is for patients starting a new line, not adding to failed R2) 3
Critical Decision Points:
If early relapse (<12-24 months from initial diagnosis): This indicates POD24, a poor prognostic indicator requiring novel approaches 3. Consider CAR T-cell therapy or bispecific antibody monotherapy.
If rituximab-refractory (progression during or <6 months after rituximab): Switch to obinutuzumab-based regimen or non-chemotherapy approaches 2.
If later relapse with adequate prior response to rituximab: Consider epcoritamab monotherapy, CAR T, or other bispecific antibodies 3.
The Evidence for Epcoritamab + R2
The EPCORE FL-1 trial demonstrated that epcoritamab + R2 versus R2 alone achieved 95% vs 79% overall response rate and dramatically improved progression-free survival (HR 0.21, p<0.0001) 1. However, this was in patients starting a new line of therapy—both arms received R2, with one arm getting epcoritamab added from the beginning.
This is fundamentally different from your scenario where the patient has already failed R2. There is no evidence that adding epcoritamab to ongoing/failed R2 provides benefit.
Common Pitfall to Avoid
Do not confuse "combination therapy" with "sequential add-on therapy." The bispecific antibody combinations studied (epcoritamab + R2, epcoritamab + bendamustine-rituximab) were designed as complete regimens initiated together 1, 4, 5. Adding epcoritamab to a failing regimen is not supported by evidence and wastes the opportunity to use epcoritamab optimally—either as monotherapy or as part of a fresh combination regimen.
Recommended Approach
Switch to epcoritamab monotherapy (approved for ≥2 prior lines including your failed R2) or consider CAR T-cell therapy if the patient meets criteria (particularly if POD24 or high-risk features) 3. If you want to use epcoritamab in combination, it should be with a different backbone than the one that just failed (e.g., epcoritamab + bendamustine-rituximab if not previously exposed to bendamustine) 5.
The safety profile of epcoritamab is manageable with predominantly low-grade cytokine release syndrome (grade 1-2 in 26-33% of patients, all resolved) 1, 4.