Minimal Residual Disease in Multiple Myeloma: Potential for Blood-Based Methods to Monitor Disease.

In recent years, the life expectancy of Multiple Myeloma (MM) patients has substantially improved, but this cancer remains incurable with increasing incidence in the developed world. Most MM patients will eventually relapse due to residual drug-resistant cancerous cells that survive treatment, commonly referred to as minimal residual disease (MRD). Methods to improve MRD detection in MM patients are generating considerable interest as a means of monitoring patients' response to treatment. In clinical laboratories, these methods currently require bone marrow aspirates which are invasive and frequently miss detection of localised disease due to the spatial heterogeneity of disease infiltration. By simplifying serial sampling and allowing for the detection of extramedullary disease, a blood-based method could significantly impact treatment duration and intensity and minimise chemotherapy-induced toxicity. This review will describe the current blood-based techniques available to detect MRD in MM and compare their potential to evaluate patient prognosis and drive therapeutic decisions.

Clinical Implications of Minimal Residual Disease Detection in Infants With KMT2A-Rearranged Acute Lymphoblastic Leukemia Treated on the Interfant-06 Protocol.

PURPOSE: Infant acute lymphoblastic leukemia (ALL) is characterized by a high incidence of KMT2A gene rearrangements and poor outcome. We evaluated the value of minimal residual disease (MRD) in infants with KMT2A-rearranged ALL treated within the Interfant-06 protocol, which compared lymphoid-style consolidation (protocol IB) versus myeloid-style consolidation (araC, daunorubicin, etoposide/mitoxantrone, araC, etoposide). MATERIALS AND METHODS: MRD was measured in 249 infants by DNA-based polymerase chain reaction of rearranged KMT2A, immunoglobulin, and/or T-cell receptor genes, at the end of induction (EOI) and end of consolidation (EOC). MRD results were classified as negative, intermediate (< 5 × 10-4), and high (≥ 5 × 10-4). RESULTS: EOI MRD levels predicted outcome with 6-year disease-free survival (DFS) of 60.2% (95% CI, 43.2 to 73.6), 45.0% (95% CI, 28.3 to 53.1), and 33.8% (95% CI, 23.8 to 44.1) for infants with negative, intermediate, and high EOI MRD levels, respectively (P = .0039). EOC MRD levels were also predictive of outcome, with 6-year DFS of 68.2% (95% CI, 55.2 to 78.1), 40.1% (95% CI, 28.1 to 51.9), and 11.9% (95% CI, 2.6 to 29.1) for infants with negative, intermediate, and high EOC MRD levels, respectively (P < .0001). Analysis of EOI MRD according to the type of consolidation treatment showed that infants treated with lymphoid-style consolidation had 6-year DFS of 78.2% (95% CI, 51.4 to 91.3), 47.2% (95% CI, 33.0 to 60.1), and 23.2% (95% CI, 12.1 to 36.4) for negative, intermediate, and high MRD levels, respectively (P < .0001), while for myeloid-style-treated patients the corresponding figures were 45.0% (95% CI, 23.9 to 64.1), 41.3% (95% CI, 23.2 to 58.5), and 45.9% (95% CI, 29.4 to 60.9). CONCLUSION: This study provides support for the idea that induction therapy selects patients for subsequent therapy; infants with high EOI MRD may benefit from AML-like consolidation (DFS 45.9% v 23.2%), whereas patients with low EOI MRD may benefit from ALL-like consolidation (DFS 78.2% v 45.0%). Patients with positive EOC MRD had dismal outcomes. These findings will be used for treatment interventions in the next Interfant protocol.

Impact of minimal residual negativity using next generation flow cytometry on outcomes in light chain amyloidosis.

We evaluated bone marrow minimal residual disease (MRD) negativity in 44 patients with light chain (AL) amyloidosis using next generation flow cytometry (sensitivity ≥1 × 10-5 ; median events analyzed: 8.7 million, range: 4.8 to 9.7 million). All patients underwent MRD testing in 2 years from start of therapy (median: 7 months). The overall MRD negative rate was 64% (n = 28). The MRD-negative rate after one-line of therapy was 71% (20/28). And, MRD negative rates were higher with stem-cell transplant as first-line therapy (86%, 18/21) vs chemotherapy alone as first-line treatment (29%, 2/7), P = .005. The MRD negative rate amongst patients in complete response was 75% (15/20), and in very good partial response, 50% (11/22). There were two patients in partial response/rising light chains (with renal dysfunction) who were MRD negative. There were no differences in baseline characteristics of MRD negative vs MRD positive patients, except younger age amongst MRD-negative patients. Patients with MRD negativity were more likely to have achieved cardiac response at the time of MRD assessment, 67% (8/12) vs 22% (2/7), P = .04. Renal response rates were similar in both groups. Progression free survival was assessed in the 42 patients achieving CR or VGPR. After median follow-up of 14 months, the estimated 1-year progression free survival in MRD negative vs MRD positive patients was 100% (26 patients, 0 events) vs 64% (16 patients, five events), P = .006, respectively. MRD assessment should be explored as a surrogate endpoint in clinical trials and MRD risk-adapted trials may help optimize treatment in AL amyloidosis.

CCL5 promotes breast cancer recurrence through macrophage recruitment in residual tumors.

Over half of breast-cancer-related deaths are due to recurrence 5 or more years after initial diagnosis and treatment. This latency suggests that a population of residual tumor cells can survive treatment and persist in a dormant state for many years. The role of the microenvironment in regulating the survival and proliferation of residual cells following therapy remains unexplored. Using a conditional mouse model for Her2-driven breast cancer, we identify interactions between residual tumor cells and their microenvironment as critical for promoting tumor recurrence. Her2 downregulation leads to an inflammatory program driven by TNFα/NFκB signaling, which promotes immune cell infiltration in regressing and residual tumors. The cytokine CCL5 is elevated following Her2 downregulation and remains high in residual tumors. CCL5 promotes tumor recurrence by recruiting CCR5-expressing macrophages, which may contribute to collagen deposition in residual tumors. Blocking this TNFα-CCL5-macrophage axis may be efficacious in preventing breast cancer recurrence.

Post-operative wall shear stress in the superior mesenteric artery: Biomarker of long term outcome in patients with residual disease after incomplete cytoreductive surgery for pseudomyxoma peritonei.

BACKGROUND: After incomplete cytoreductive surgery (CRS), the assessment of pseudomyxoma peritonei (PMP) progression remains challenging. The objective was to assess the efficacy of wall shear stress (WSS) measured in superior mesenteric artery (SMA) to predict PMP progression in the postoperative setting to propose additional treatments. METHODS: In a prospective study, 52 patients with PMP had Doppler-ultrasound examination of the SMA with WSS calculation within one year after CRS with a mean follow-up of 43.3 ±â€¯18.3 months. Patients were categorized according to the completeness of CRS and clinical outcome: Group-1 (n = 19): complete CRS and no recurrence, group-2 (n = 20): incomplete CRS with slowly progressive disease (alive at 2 years without severe clinical symptoms), group-3 (n = 13): incomplete CRS and severe clinical symptoms or dead within two years. Results of WSS were compared between groups and to 24 healthy subjects. RESULTS: WSS measured in the SMA was superior in Group-3 (19.6 ±â€¯8.2 dynes/cm2) than in Group-2 (9.2 ±â€¯1.8 dynes/cm2, p = 1.10-6), Group-1 (10.4 ±â€¯2.8 dynes/cm2, p = 8.10-5), and healthy patients (8.7 ±â€¯2.8 dynes/cm2, p = 9.10-7). One year after surgery, among patients with incomplete CRS a cut-off value of 12.1dynes/cm2 allowed distinguishing patients without from those with severe disease progression with a sensitivity of 100% and a specificity of 100% (p < 1.10-4) AUC = 1.000 [95%CI: 0.897-1.000]. CONCLUSION: Post-operative assessment of the WSS in the SMA in patients with incomplete CRS for PMP should be considered as biomarker of tumor progression in the postoperative setting. Therefore, WSS could be useful to target patients needing adjuvant systemic chemotherapy one year after CRS.

Degrees of Diaphragma Sellae Descent during Transsphenoidal Pituitary Adenoma Resection: Predictive Factors and Effect on Outcome.

This study is aimed to classify degrees of diaphragma sellae (DS) descent into sella turcica according to the surgical field block caused by the descent and to construct predictive imaging criteria for the degree of descent, and in addition, to determine whether there is any correlation between the degree of DS descent and the operative outcome (in the form of cerebrospinal fluid leak and/or presence of residual tumor). Totally, 72 patients were enrolled in our study. Their clinical and radiological data as well as the high definition videos of operations were retrospectively reviewed. The degree of DS descent during the operation was classified into five degrees according to surgical field block caused by the descent. We investigated the correlation between these five degrees and the clinical findings, radiological findings as well as the surgical outcomes. We found that the most important determining factors of DS descent degree were the volume and the height of the tumor portion above diaphragma opening. On the other hand, the total tumor volume, the maximum tumor height and the morphological pattern according to Wilson's system (modified from Hardy) had no statistically significant correlation with DS degree of descent. Presence of residual tumor on postoperative magnetic resonance images was significantly correlated with Wilson's classification and with supradiaphragmatic tumor height. On the other hand, cerebrospinal fluid leak showed no statistically significant difference between variable degrees of DS descent. Volumetric data of the tumor portion above the diaphragma opening are more important than morphological data for prediction of surgical field block caused by descended DS. While DS prolapse significantly increases the difficulty of the operative procedure, residual tumor presence is mainly dependent on morphological classification, especially cavernous sinus invasion.

Intra-operative spectroscopic assessment of surgical margins during breast conserving surgery.

BACKGROUND: In over 20% of breast conserving operations, postoperative pathological assessment of the excised tissue reveals positive margins, requiring additional surgery. Current techniques for intra-operative assessment of tumor margins are insufficient in accuracy or resolution to reliably detect small tumors. There is a distinct need for a fast technique to accurately identify tumors smaller than 1 mm2 in large tissue surfaces within 30 min. METHODS: Multi-modal spectral histopathology (MSH), a multimodal imaging technique combining tissue auto-fluorescence and Raman spectroscopy was used to detect microscopic residual tumor at the surface of the excised breast tissue. New algorithms were developed to optimally utilize auto-fluorescence images to guide Raman measurements and achieve the required detection accuracy over large tissue surfaces (up to 4 × 6.5 cm2). Algorithms were trained on 91 breast tissue samples from 65 patients. RESULTS: Independent tests on 121 samples from 107 patients - including 51 fresh, whole excision specimens - detected breast carcinoma on the tissue surface with 95% sensitivity and 82% specificity. One surface of each uncut excision specimen was measured in 12-24 min. The combination of high spatial-resolution auto-fluorescence with specific diagnosis by Raman spectroscopy allows reliable detection even for invasive carcinoma or ductal carcinoma in situ smaller than 1 mm2. CONCLUSIONS: This study provides evidence that this multimodal approach could provide an objective tool for intra-operative assessment of breast conserving surgery margins, reducing the risk for unnecessary second operations.

Minimal residual disease in chronic lymphocytic leukemia: A consensus paper that presents the clinical impact of the presently available laboratory approaches.

Chronic lymphocytic leukemia (CLL) is a malignancy defined by the accumulation of mature lymphocytes in the lymphoid tissues, bone marrow, and blood. Therapy for CLL is guided according to the Rai and Binet staging systems. Nevertheless, state-of-the-art protocols in disease monitoring, diagnostics, and prognostics for CLL are based on the assessment of minimal residual disease (MRD). MRD is internationally considered to be the level of disease that can be detected by sensitive techniques and represents incomplete treatment and a probability of disease relapse. MRD detection has been continuously improved by the quick development of both flow cytometry and molecular biology technology, as well as by next-generation sequencing. Considering that MRD detection is moving more and more from research to clinical practice, where it can be an independent prognostic marker, in this paper, we present the methodologies by which MRD is evaluated, from translational research to clinical practice.

Minimal Residual Disease at First Achievement of Complete Remission Predicts Outcome in Adult Patients with Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia.

We evaluated the prognostic effect of minimal residual disease at first achievement of complete remission (MRD at CR1) in adult patients with Philadelphia chromosome-negative acute lymphoblastic leukemia (ALL). A total of 97 patients received treatment in our center between 2007 and 2012 were retrospectively reviewed in this study. Patients were divided into two arms according to the post-remission therapy (chemotherapy alone or allogeneic hematopoietic stem cell transplantation (allo-HSCT)) they received. MRD was detected by four-color flow cytometry. We chose 0.02% and 0.2% as the cut-off points of MRD at CR1 for risk stratification using receiver operating characteristic analysis. The 3-year overall survival (OS) and leukemia free survival (LFS) rates for the whole cohort were 46.2% and 40.5%. MRD at CR1 had a significantly negative correlation with survival in both arms. Three-year OS rates in the chemotherapy arm were 70.0%, 25.2%, 0% (P = 0.003) for low, intermediate, and high levels of MRD at CR1, respectively. Three-year OS rates in the transplant arm were 81.8%, 64.3%, 27.3% (P = 0.005) for low, intermediate, and high levels of MRD at CR1, respectively. Multivariate analysis confirmed that higher level of MRD at CR1 was a significant adverse factor for OS and LFS. Compared with chemotherapy alone, allo-HSCT significantly improved LFS rates in patients with intermediate (P = 0.005) and high (P = 0.022) levels of MRD at CR1, but not patients with low level of MRD at CR1 (P = 0.851). These results suggested that MRD at CR1 could strongly predict the outcome of adult ALL. Patients with intermediate and high levels of MRD at CR1 would benefit from allo-HSCT.

Reoperative Retroperitoneal Surgery: Etiology and Clinical Outcome.

Retroperitoneal recurrences following retroperitoneal lymph node dissection (RPLND) are rare events and, with few exceptions, should be regarded as either surgical or technical failures, or a result of inappropriate modifications to the original RPLND template. Although not a substitute for an adequate initial RPLND, reoperative retroperitoneal surgery is a viable option for properly selected patients. In the hands of experienced surgeons at tertiary care centers, reoperative retroperitoneal surgery is associated with long-term survival in a significant proportion of patients, with an acceptable degree of morbidity.

Functional plasticity of language confirmed with intraoperative electrical stimulations and updated neuronavigation: case report of low-grade glioma of the left inferior frontal gyrus.

Removal of glioma from the dominant side of the inferior frontal gyrus (IFG) is associated with a risk of permanent language dysfunction. While intraoperative cortical and subcortical electrical stimulations can be used for functional language mapping in an effort to reduce the risk of postoperative neurological impairment, the extent of resection is limited by the functional boundaries. Recent reports proposed that a two-stage surgical approach for low-grade glioma in eloquent areas could avoid permanent deficits via the functional plasticity that occurs between the two operations. The report describes a patient with World Health Organization (WHO) grade II oligoastrocytoma in the left IFG, in functional plasticity of language occurred in the interval between two consecutive surgeries. Intraoperative electrical stimulations suggested that a language area and related subcortical fiber crossed the pre-central sulcus during tumor progression owing to functional plasticity. In the present case, we integrated neurophysiological data into the intraoperative neuronavigation system. We also confirmed the peri-lesional shift of language area and related subcortical fiber on image findings. Consequently, the tumor was sub-totally removed with two separate resections. Permanent language disturbance did not occur, and this favorable outcome was attributed to functional plasticity. The present experience sustains the multistage approach for low-grade gliomas in the language area. A combination of intraoperative electrical stimulations and updated neuronavigation may facilitate the characterization of brain functional plasticity.

Nonfunctioning pituitary adenomas: association of Ki-67 and HMGA-1 labeling indices with residual tumor growth.

BACKGROUND: The postoperative biological behavior of nonfunctioning pituitary adenomas (NFPAs) is variable. Some residual NFPAs are stable long-term, others grow, and some recur despite complete removal. The usual histological markers of tumor aggressiveness are often similar between recurring, regrowing, and stable tumors, and therefore are not reliable as prognostic parameters. In this study, the clinical utility of proliferation indices (labeling index, Li) based on immunohistochemistry targeted at antigens Ki-67 and High-mobility group A1 (HMGA-1) for prediction of NFPA prognosis was investigated. METHODS: Fifty patients with NFPAs were investigated. In each patient, Ki-67 and HMGA-1 Li were evaluated. Based on postoperative magnetic resonance images, patients were classified as tumor-free (18 patients), or harboring a residual tumor (32 patients). The latter group was further subdivided into groups with stable tumor remnants (11 patients) or progressive tumor remnants (21 patients). RESULTS: The median follow-up period was 8 years. No significant relationship between HMGA-1 Li and residual tumor growth was found. Growing residual tumors showed a trend towards higher Ki-67 Li compared with stable ones (p = 0.104). All tumor remnants with Ki-67 Li above 2.2% were growing. The relationship between residual tumor growth and Ki-67 Li exceeding the cutoff value of 2.2% was significant (p = 0.01 in univariate, p = 0.044 in multivariate analysis). CONCLUSIONS: The prognostic significance of the HMGA-1 antigen was not confirmed. In contrast, the Ki-67 Li provides useful and valuable information for the postoperative management of NFPAs. In residual adenomas with a Ki-67 Li above 2.2%, regrowth should be expected, and these tumors may require shorter intervals of follow-up magnetic resonance imaging (MRI) and/or early adjuvant therapy. Future larger studies are needed to confirm the results of this study.

PCR for monitoring of minimal residual disease in hematologic malignancy.

Monitoring minimal residual disease (MRD) is useful to evaluate therapeutic response and risk of relapse in patients with hematologic malignancy. Currently available quantitative MRD assays are fluorescence in situ hybridization of chromosomal aberrations; multiparameter flow cytometry of leukemia-associated immunophenotypes; and quantitative polymerase chain reaction (qPCR) analysis of fusion genes, immunoglobulin/T-cell receptor gene rearrangements, genetic alterations, or over-expressed genes. Among the PCR-based markers, genetic alterations are found in acute myelogenous leukemia patients with cytogenetically normal karyotype and can be considered as applicable targets for monitoring of MRD. Screening, confirmation and quantification procedures are important to develop the patient- or tumor-specific MRD assays using the PCR-based markers. Wild-type blocking PCR or coamplification at lower denaturing temperature-PCR is suited for screening of low-abundant genetic alterations, and allele-specific qPCR using primers including mismatched base and locked nucleic acids can quantify not only insertion and duplication of several nucleotides but also single nucleotide mutation in the presence of an excess amount of wild-type nucleotides. In addition to the well-established MRD markers, such as immunoglobulin/T-cell receptor gene rearrangements and fusion genes, utilizing potential MRD markers such as genetic alterations may expand the spectrum of patients in whom MRD can be monitored.

Environmental-mediated drug resistance: a target for multiple myeloma therapy.

Multiple myeloma is an incurable malignancy of mature clonal B cells. The refractory nature of this disease has long been attributed to the acquisition of drug resistance. Traditionally, mechanisms of drug resistance have been defined by genetic, acquired changes in the expression or function of specific genes products. However, over the past 10 years a large body of evidence has emerged demonstrating that in addition to mechanisms of drug resistance intrinsic to the cancer cell, there exist dynamic, de novo mechanisms coordinated by the tumor microenvironment resulting in a environmental-mediated drug resistance (EM-DR). Within this review we will provide an overview of some of these mechanisms of drug resistance and how they contribute to minimal residual disease and subsequent treatment failure. By understanding mechanisms of EM-DR, therapeutic targets can be identified and interventions designed to reduce minimal residual disease and improve clinical outcomes.

Monitoring minimal residual disease in patients with chronic myeloid leukemia after treatment with tyrosine kinase inhibitors.

PURPOSE OF THE REVIEW: Monitoring for residual leukemic burden is an integral part of ongoing evaluation in chronic myeloid leukemia. With high rates of complete cytogenetic response induced by imatinib and other tyrosine kinase inhibitors, exploring refinements in current methods of minimal residual disease monitoring is relevant. RECENT FINDINGS: Estimation of leukemic burden can influence treatment decisions. Real-time RT-PCR has become the method of choice for quantifying bcr-abl transcripts in patients undergoing therapy. Efforts are in progress to standardize this technique. The numbers of bcr-abl transcripts can vary in serial specimens, and it is important that changes in treatment (e.g. referral for transplantation, imatinib dose increase, or switch to a new tyrosine kinase inhibitor) be based on consistent rises in transcript number over time rather than on a single change. SUMMARY: Prognosis in newly diagnosed patients with chronic myeloid leukemia in chronic phase has dramatically improved with the availability of imatinib and other tyrosine kinase inhibitors. In parallel, methods of monitoring minimal residual disease are evolving. Although real-time RT-PCR is now a standard monitoring method, the clinical significance of frequent and more precise follow up in patients achieving a complete cytogenetic response requires better definition.

CD34+ leukemic subpopulation predominantly displays lower spontaneous apoptosis and has higher expression levels of Bcl-2 and MDR1 genes than CD34- cells in childhood AML.

In view of obscure clinical and biological significance of leukemic cells heterogeneity, we studied the efficacy of apoptosis, proliferation, and expression levels of the Bcl-2, MDR1, LRP, and BCRP genes in sorted CD34+ and CD34- subpopulations of childhood AML leukemic samples. In five out of nine cases, CD34+ cells were less sensitive to spontaneous apoptosis and had from 1.2- to 5.0-fold higher expression levels of Bcl-2 (eight of ten) and from 1.5- to 28.7-fold higher expression levels of MDR1 (eight of ten). The expression levels of the LRP gene were from 1.1- to 1.8-fold higher in CD34+ subpopulations (five of ten cases), and the expression levels of the BCRP gene were from 1.1- to 22.4-fold higher in CD34+ leukemic cells (six of ten). In all M4 cases, the expression levels of LRP were higher in the CD34- subpopulation. Significant differences in the patterns of genes expression between patients do not allow us to conclude that the CD34+ fractions have more resistant phenotype than the CD34- subpopulations. Nevertheless, distinctions between CD34+ and CD34- cells may lead to different chemosensitivities between leukemic subpopulations in vivo and may determine the alteration of the leukemic immunophenotype during treatment and in relapse.

Tumor dormancy and cancer stem cells: implications for the biology and treatment of breast cancer metastasis.

Breast cancer remains a leading cause of morbidity and mortality in women, mainly due to the propensity of primary breast tumors to metastasize to regional and distant sites. Metastatic spread after the removal of a primary tumor can be difficult to identify, creating uncertainty in patients with regards to possible cancer recurrence. This is a particular problem in breast cancer, exemplified by the fact that recurrence can take place after decades of apparent disease-free survival. The mechanisms underlying tumor dormancy in breast cancer remain poorly understood, and this presents significant challenges to both experimental investigation and clinical management of breast cancer. This review will discuss what is currently known about the metastatic process and tumor dormancy, consider the growing evidence that cancer stem cells may contribute to tumor progression and dormancy, and speculate about the clinical importance and implications of this research.

'Vanishing' prostate cancer in radical prostatectomy specimens: incidence and long-term follow-up in 38 cases.

OBJECTIVE: To determine the incidence and long-term follow-up of the 'vanishing cancer' phenomenon, as complete sampling of some radical prostatectomy (RP) specimens reveals no residual cancer. MATERIALS AND METHODS: The Mayo Clinic prostate cancer RP database for 1966-1995 was searched for all cases in which there was no residual adenocarcinoma (pathological stage pT0). Each case was confirmed by a review of all tissue specimen slides. Various clinical and pathological features were evaluated, and the follow-up obtained for all patients. RESULTS: Among 6843 RPs there were 38 in which no residual cancer was identified despite careful sampling. There was a 10-fold decline in the incidence of this finding, from 2.1% before 1980 to 0.2% in 1993-95; this decline appeared to be caused by a decrease in the frequency of diagnosis of cancer by transurethral resection from > 10% before 1990 to < 2% in 1993-95. The mean (range) age of the patients was 63 (38-75) years. All cancers on biopsy or transurethral resection were well or moderately differentiated; clinical stages included T1a (42% of cases), T1b (45%) and T2 (13%). Six patients had a nerve-sparing RP, all after 1990. The mean follow-up was 9.6 (1.0-28.5) years, and there were no recurrences of cancer; the serum prostate specific antigen concentration remained at < 0.2 ng/mL in surviving patients. Six patients (16%) died from intercurrent disease. CONCLUSIONS: The incidence of 'vanishing cancer' declined between 1966 and 1995, probably as a result of the decline in the use of transurethral resection, occurring in 0.2% of RPs. The prognosis in such patients is excellent, indicating that there is no apparent clinical significance to microscopic foci of cancer that remain undetected after reasonably complete pathological sampling. The inability to identify cancer in a prostate removed for biopsy-confirmed carcinoma does not indicate technical failure.