Indeterminate measurable residual disease by multiparameter flow cytometry is associated with an intermediate risk of clinical relapse in adult patients with acute leukaemia.

Measurable residual disease (MRD) is useful for prognostication and for monitoring response to treatment in patients with acute leukaemia. MRD by multiparametric flow cytometry (MFC-MRD) utilises the leukaemia-associated immunophenotype (LAIP) and difference from normal (DfN) strategies to identify the leukaemic clone. Difficulties arise when the LAIP overlaps with normal regeneration, there is clonal evolution, or when the abnormal clone population is exceptionally small e.g., <0.01% of CD45+ cells. Such cases are reported as 'indeterminate'; however, there is little international consensus on this reporting. The relationship between clinical outcomes and indeterminate MFC-MRD is unknown. Here we determine the rate of indeterminate MFC-MRD reporting, its relationship to concurrent molecular MRD results when available, and to clinical outcomes to 12 months. We performed an internal audit of all adult testing for MFC-MRD between January and December 2021. A total of 153 consecutive patients with a diagnosis of acute leukaemia were included. Successive MFC-MRD results and clinical outcomes were recorded over a 12-month period from time of inclusion into the study. In total, 460 MFC-MRD tests from 153 patients were reviewed and 73 (16%) MFC-MRD tests from 54 (35%) patients were reported as indeterminate. The majority (70%) were at low levels between 0.01-0.1% of CD45+ cells. Compared to patients with a negative result, acute myeloid leukaemia (AML) was more frequent in patients who had an indeterminate MFC-MRD (70% vs 36%), and B-cell acute lymphoblastic leukaemia was less common (20% vs 55%). In patients with indeterminate MFC-MRD results, one-third had received either chemotherapy or allogeneic haemopoietic stem cell transplant (aHSCT) within the preceding 3 months. Agreement between MFC and molecular MRD testing was low. Patients with indeterminate MFC-MRD had leukaemia relapse rates below patients with a positive MFC-MRD, but greater than those with negative MFC-MRD (positive 33% vs indeterminate 21% vs negative 8%, p = 0.038). Overall, these findings indicate that indeterminate MFC-MRD results are more common in adults with AML and also in those who have received chemotherapy or aHSCT within the previous 3 months. We report for the first time that indeterminate MFC-MRD is a finding of potential clinical significance, which associates with a numerically higher median relapse rate within 12 months when compared to a negative MFC-MRD result.

Early Postoperative Low Expression of RAD50 in Rectal Cancer Patients Associates with Disease-Free Survival.

BACKGROUND: Molecular biomarkers have the potential to predict response to the treatment of rectal cancer. In this study, we aimed to evaluate the prognostic and clinicopathological implication of RAD50 (DNA repair protein RAD50 homolog) expression in rectal cancer. METHODS: A total of 266 rectal cancer patients who underwent surgery and received chemo- and radiotherapy between 2000 and 2011 were involved in the study. Postoperative RAD50 expression was determined by immunohistochemistry in surgical samples (n = 266). RESULTS: Using Kaplan-Meier survival analysis, we found that low RAD50 expression in postoperative samples was associated with worse disease free survival (p = 0.001) and overall survival (p < 0.001) in early stage/low-grade tumors. In a comparison of patients with low vs. high RAD50 expression, we found that low levels of postoperative RAD50 expression in rectal cancer tissues were significantly associated with perineural invasion (p = 0.002). CONCLUSION: Expression of RAD50 in rectal cancer may serve as a prognostic biomarker for long-term survival of patients with perineural invasion-positive tumors and for potential use in early stage and low-grade rectal cancer assessment.

MRE11 and ATM Expression Levels Predict Rectal Cancer Survival and Their Association with Radiotherapy Response.

BACKGROUND: Aberrant expression of DNA repair proteins is associated with poor survival in cancer patients. We investigated the combined expression of MRE11 and ATM as a predictive marker of response to radiotherapy in rectal cancer. METHODS: MRE11 and ATM expression were examined in tumor samples from 262 rectal cancer patients who underwent surgery for rectal cancer, including a sub-cohort of 54 patients who were treated with neoadjuvant radiotherapy. The relationship between expression of the two-protein panel and tumor regression grade (TRG) was assessed by Mann-Whitney U test and receiver operating characteristics area under curve (ROC-AUC) analysis. The association between expression of the two-protein panel and clinicopathologic variables and survival was examined by Kaplan-Meier methods and Cox regression analysis. RESULTS: A high score for two-protein combined expression in the tumor center (TC) was significantly associated with worse disease-free survival (DFS) (P = 0.035) and overall survival (OS) (P = 0.003) in the whole cohort, and with DFS (P = 0.028) and OS (P = 0.024) in the neoadjuvant subgroup (n = 54). In multivariate analysis, the two-protein combination panel (HR = 2.178, 95% CI 1.115-4.256, P = 0.023) and perineural invasion (HR = 2.183, 95% CI 1.222-3.899, P = 0.008) were significantly associated with DFS. Using ROC-AUC analysis of good versus poor histological tumor response among patients treated preoperatively with radiotherapy, the average ROC-AUC was 0.745 for the combined panel, 0.618 for ATM alone, and 0.711 for MRE11 alone. CONCLUSIONS: The MRE11/ATM two-protein panel developed in this study may have clinical value as a predictive marker of tumor response to neoadjuvant radiotherapy, and a prognostic marker for disease-free and overall survival.