Bone marrow minimal residual disease was an early response marker and a consistent independent predictor of survival after anti-GD2 immunotherapy

Abstract

Purpose: Immunotherapy is a standard of care for children with high-risk neuroblastoma, where bone marrow (BM) is the predominant metastatic site. Early response markers of minimal residual disease (MRD) in the BM that are also predictive of survival could help individualize patient therapies.

Patients and methods: After achieving first remission (n = 163), primary refractory disease (n = 102), or second remission (n = 95), children with stage 4 neuroblastoma received anti-GD2 3F8 antibody immunotherapy. BM MRD before 3F8 treatment and after cycle 2 (postMRD) was measured using a four-marker panel (B4GALNT1, PHOX2B, CCND1, and ISL1) by quantitative reverse transcription polymerase chain reaction. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Prognostic variables were tested in both univariable and multivariable analyses, and MRD markers were further assessed individually and in combination as binary composite (postMRD: 0 and 1) and as equal sum (postMRDSum: 0 to 4) using the Cox regression models, and their predictive accuracy was determined by the concordance index.

Results: When BM was evaluated after cycle 2, individual markers were highly predictive of PFS and OS. The prediction accuracy improved when they were combined in postMRDSum. A multivariable model taking into account all the variables significant in the univariable analyses identified postMRDSum to be independently predictive of PFS and OS. When the model for OS also included missing killer immunoglobulin-like receptor ligand, human antimouse antibody response, and the enrollment disease status, the concordance index was 0.704.

Conclusion: BM MRD after two cycles of immunotherapy was confirmed as an early response marker and a consistent independent predictor of survival.

Fig 1.

Prognostic impact of minimal residual disease after cycle 2 (postMRD) using the four-marker panel on overall survival stratified according to the clinical groups, including the number of at-risk patients. PostMRD is the composite of the four-marker panel, where negative indicates that all markers are negative and positive indicates that at least one marker is positive. Log-rank P values testing the effect of postMRD on overall survival in each clinical group are included.

Fig 2.

Prognostic impact of individual postMRD marker positivity on progression-free survival, including the number of at-risk patients: (A) post-B4GALNT1; (B) post-PHOX2B; (C) post-CCND1; and (D) post-ISL1. Except for post-CCND1 in the second remission cohort (P = .02), the log-rank P value for every other individual marker in each clinical group was P < .001. PostMRD, minimal residual disease after cycle 2 of 3F8.

Fig 3.

Pairwise correlations between minimal residual disease (MRD) markers (preMRD and postMRD) among the three clinical cohorts. postMRD, MRD measured after two cycles of 3F8; preMRD, MRD measured before 3F8.

Fig A1.

Prognostic impact of minimal residual disease after cycle 2 (postMRD) using the four-marker panel on progression-free survival stratified according to clinical groups. PostMRD is the composite of the four-marker panel, where negative indicates that all markers are negative and positive indicates that at least one marker is positive.

Fig A2.

Prognostic impact of individual postMRD marker positivity on overall survival: (A) post-B4GALNT1; (B) post-PHOX2B; (C) post-CCND1; and (D) post-ISL1. PostMRD, minimal residual disease after cycle 2 of 3F8.

Fig A3.

Prognostic significance of postMRDSum on progression-free survival among the three clinical groups: (A) primary refractory, (B) first remission, and (C) second remission. PostMRDSum indicates post-B4GALNT1 plus post-PHOX2B plus post-CCND1 plus post-ISL1, where each marker was given an equal weight, with a value of 0, 1, 2, 3, or 4. PostMRD, minimal residual disease after cycle 2 of 3F8.

Fig A4.

Prognostic significance of postMRDSum on overall survival among the three clinical groups: (A) primary refractory, (B) first remission, and (C) second remission. PostMRD, minimal residual disease after cycle 2 of 3F8.