Achievement of serologic undetectability defined by standard laboratory assays was associated with superior overall survival and progression-free survival in multiple myeloma patients monitored without repeated bone marrow studies.
Key Findings
Results
Serologic undetectability was achieved by approximately one-third of patients and was associated with significantly lower risk of death.
29 patients (33.0%) met all criteria for complete serologic undetectability, defined as negative SPEP/IF together with normalization of the κ/λ sFLC ratio.
Achievement of serologic undetectability was associated with a hazard ratio for death of 0.42 (95% CI 0.19–0.91; p=0.0483).
The study included 88 consecutive patients diagnosed with MM between 1999 and 2024 at a single institution.
Patients with missing sFLC assays were conservatively analyzed in the serologically positive cohort.
Results
Serologic undetectability was associated with significantly longer progression-free survival.
Hazard ratio for progression or death among serologically undetectable patients was 0.195 (95% CI 0.091–0.418; p=0.0028).
Disease progression or relapse occurred in 28 patients overall across the entire cohort.
Survival analyses used Kaplan-Meier methods, log-rank testing, and univariable Cox proportional hazards models.
Potential guarantee-time (immortal-time) bias associated with post-baseline response endpoints was taken into account in the analysis.
Results
More than half of patients achieved disappearance of the monoclonal band on SPEP/immunofixation, but fewer met full criteria for serologic undetectability.
52 patients (59.1%) achieved disappearance of the monoclonal band on SPEP/IF.
Only 29 patients (33.0%) met all criteria for complete serologic undetectability, which additionally required normalization of the κ/λ sFLC ratio.
Serial serum protein electrophoresis and immunofixation were the primary monitoring tools, with sFLC assays used when available.
Results
Among serologically undetectable patients, those undergoing autologous stem cell transplantation showed a numerical trend toward improved outcomes that did not reach statistical significance.
The trend toward improved outcomes with ASCT among serologically undetectable patients did not reach statistical significance due to sample size constraints.
The analysis was limited by the single-center retrospective design and cohort size of 88 patients.
The study period spanned 1999 to 2024, encompassing a wide range of treatment eras.
Conclusions
Comprehensive serologic monitoring using standard laboratory assays was proposed as a feasible non-invasive alternative to repeated bone marrow-based MRD assessment in resource-limited settings.
All patients underwent bone marrow evaluation at diagnosis but were subsequently monitored using only serial SPEP, immunofixation, and sFLC assays.
Bone marrow evaluations for MRD assessment were described as invasive, costly, and not universally accessible.
The authors concluded that serologic monitoring 'offers a feasible, non-invasive alternative for longitudinal disease evaluation' when repeated bone marrow-based MRD evaluations are not feasible.
The study was retrospective and single-center, conducted at a single institution.
What This Means
This research suggests that doctors can gain meaningful information about how well multiple myeloma treatment is working by using standard blood tests — specifically serum protein electrophoresis, immunofixation, and serum free light chain assays — without repeatedly performing bone marrow biopsies. In a group of 88 patients followed over 25 years at a single hospital, patients whose blood tests showed complete disappearance of the abnormal protein produced by myeloma cells (called serologic undetectability) lived significantly longer and had their disease under control for significantly longer periods compared to patients who did not achieve this level of clearance. About one in three patients (33%) achieved full serologic undetectability as defined by all three test criteria being negative or normalized.
This research suggests that the degree of response visible in routine blood tests carries real prognostic meaning — patients who cleared all detectable disease markers from their blood had roughly half the risk of dying and about one-fifth the risk of disease progression compared to those who did not. This is clinically relevant because bone marrow biopsies, which are currently the standard method for detecting residual disease in myeloma, are painful, expensive, and not always available, particularly in lower-resource healthcare settings.
The findings suggest that for clinics or healthcare systems where repeated bone marrow testing is not practical, comprehensive serologic monitoring using widely available blood tests may be a viable way to track how well treatment is working and to identify patients at higher or lower risk of disease progression. The study has limitations including its retrospective design, single-center setting, and relatively small sample size, which prevented some subgroup analyses (such as the effect of stem cell transplantation) from reaching statistical significance.
Alberto-López L, Melchor-Melo O, Gómez-Cabrera M, Velasco-Padilla J, Ramírez-García J, Anaya-Valdés P, et al.. (2026). Serologic follow-up in patients with multiple myeloma without repeated bone marrow studies: a single-institution experience.. Hematology (Amsterdam, Netherlands). https://doi.org/10.1080/16078454.2026.2727801