MRD-Positive at 0.02%: What a Number Just Above the Threshold Actually Means
She's in complete remission by every visible measure except one flow cytometry threshold. Whether that single number should send her straight to transplant, or toward a drug that might clear it first, depends on what the number is actually predicting.
Ana V. is two years into a chemistry PhD she has no intention of abandoning, and it was her research advisor, not Ana herself, who first noticed the fatigue and unexplained bruising that turned out to be Philadelphia-chromosome-negative B-ALL, diagnosed four months ago at 24. She completed standard induction chemotherapy and achieved morphologic complete remission — no detectable leukemia by standard bone marrow examination — but flow cytometry for measurable residual disease came back at 0.02%, above the 0.01% threshold most commonly used to define true MRD-negativity.
She is, by every visible measure, in remission, except for one number sitting just above a line that carries real prognostic weight. That single value changes the conversation meaningfully: MRD positivity after induction is a well-established predictor of eventual relapse, which is why many protocols route MRD-positive patients toward allogeneic transplant, with its own conditioning-related risk to future fertility layered on top of graft-versus-host disease and the usual transplant-related morbidity. Blinatumomab, a bispecific antibody that recruits a patient's own T-cells against CD19-positive leukemic cells, is the drug that gets reached for here — but her 0.02% is the reason it is not a clean fit. The BLAST study (Gökbuget et al., 2018) that earned blinatumomab its MRD indication enrolled patients at MRD of 0.1% or above, and the FDA indication was written to that same floor. She sits a full log below it. The trial that does describe her disease state, E1910 (Litzow et al., 2024), added blinatumomab to consolidation chemotherapy and improved overall survival — but it enrolled patients aged 30 to 70 who were MRD-negative at under 0.01%, and she is 24 and not MRD-negative. Her single number falls in the gap between two trials rather than inside either one.
For a 24-year-old who has already asked her team directly about fertility preservation before any of this began, the difference between a treatment path that might avoid transplant and one that requires it isn't an abstract quality-of-life discussion held after the medical decision is made — it's the actual question in front of her, and she has made clear she wants it treated as one. She underwent oocyte retrieval before induction started, on her own initiative after reading about it herself, a step her team credits with giving her more real options today than she otherwise would have had if the leukemia diagnosis alone had dictated the pace of every decision since.
One number just above the threshold
Consolidate with blinatumomab before committing to transplant. I'll say up front that neither trial lands squarely on her. BLAST enrolled at MRD of 0.1% and up, and she's at 0.02%; E1910 enrolled MRD-negative patients aged 30 to 70, and she's 24 and not quite negative. What both establish is that blinatumomab does real work against residual disease at the depth we can still measure, and that adding it to consolidation improved survival in patients whose disease was, if anything, less detectable than hers. At 24, avoiding transplant-related toxicity and fertility loss if we can achieve deep remission another way is a real, legitimate goal, not a lesser priority than disease control.
MRD positivity after induction is a strong, well-validated relapse predictor, and allogeneic transplant offers the most definitive long-term disease control we have. Blinatumomab clears MRD in a lot of patients — it isn't a cure on its own, and relapse after MRD conversion with blinatumomab alone is a real, documented risk that needs to be weighed honestly.
The actual question isn't whether blinatumomab works — it does, at clearing MRD. It's whether that clearing REPLACES the need for transplant, or just gets her to transplant in better shape. The evidence supports the second claim much more clearly than the first.
You're both arguing versions of a question that doesn't actually have to be resolved today.
MRD status at the time of transplant is itself independently prognostic — a patient who reaches transplant MRD-negative does better than one who reaches it MRD-positive, regardless of how they got there. So give her one cycle of blinatumomab with proper inpatient step-up dosing and CRS monitoring, recheck MRD, and make the transplant decision based on that result. If it clears, that's real information about whether transplant is still needed. If it doesn't, we've lost very little time and she goes to transplant in exactly the position you'd have wanted regardless.
Agreed, and genuinely resolved rather than left open: proceed with one cycle of blinatumomab consolidation using inpatient step-up dosing and cytokine release syndrome monitoring, then recheck MRD. If MRD clears to negative, hold transplant in reserve and continue standard maintenance with close monitoring; if MRD persists, proceed to allogeneic transplant using her identified matched sibling donor. Fertility preservation counseling was arranged in parallel regardless of which path is ultimately taken.