The prognostic value of MRD negativity has been consistently demonstrated across pediatric and adult clinical trials with various chemotherapy protocols, timing and methods of MRD assessment, and ALL disease subtypes.

MRD testing is useful for assessing quality/depth of response after induction therapy in the setting of morphological remission, and also to monitor for relapse in a patient who has achieved remission. In the first scenario, that is important because failure to achieve MRD negativity is associated with worse overall survival. Outcomes between early and late timepoints of MRD negativity (≤3 vs >3 months post-induction) are similar.

This is an opportunity to intervene by changing therapies, including use of blinatumomab for MRD positive disease or enrollment in clinical trials for novel agents.

Even in the setting of relapsed disease, achieving MRD negativity is associated with potential for long-term survival.² In patients who fail to achieve MRD negativity, allogeneic HCT as consolidation improves outcomes compared to chemotherapy alone.³ In the second scenario of using MRD to monitor for relapse, intervention in the setting of low disease burden is less likely to be associated with tumor lysis syndrome with chemotherapy and cytokine release syndrome with immunotherapy, allowing time for planning enrollment in clinical trials.

It is important to consider the timing and circumstances of MRD testing such as doing so at the end of induction, at the end of consolidation, before hematopoietic stem-cell transplantation (HSCT), after HSCT, or based on treatment response. Achieving MRD negativity prior to HSCT optimizes outcomes.

There are different methods to measure MRD in B-cell ALL and each has its strengths and limitations. The best option is the one that is available to you. It is important to use a validated MRD test with appropriate sensitivity of at least 10^-4.

Much of the clinical trial data coming out right now for CLL is talking about doublet and triplet combinations, with therapy stop dates based on MRD status at defined intervals. While MRD testing is currently only being used as part of clinical trials at our institution, it seems like more practices will be using it as part of standard clinical care moving forward so it important for practices to start laying the groundwork now to be able to more easily incorporate MRD testing as it is implemented more widely.

We are routinely doing MRD testing for patients on venetoclax and an anti-CD20 monoclonal antibody when making the decision whether to stop treatment at the one-year mark. I will also use clonoSEQ® at diagnosis for a new patient with CLL with a high burden of disease and will then follow MRD periodically to assess treatment response. This is not yet considered standard of care at my practice as knowing when to do this and with what assay will be hard, but with CLL it is not always easy to know about depth of response by looking at a CBC and scan. To be able to check MRD while on treatment, especially as doublets regimens become more common, and triplet regimens emerge in the next five years, we will need clinical pathways to help guide how MRD status informs treatment decision-making.

Patients with CLL can be on observation-only for quite some time, but once the decision is made to initiate therapy then we will obtain a clonoSEQ® ID and use this to follow MRD from there. We still need more information about how to optimally use MRD results, and when a patient is MRD-negative we consider that result along with many other variables before making a decision to recommend stopping treatment.

The majority of patients who get MRD testing at our facility are on clinical trials. I do use MRD testing, however, for patients who are on venetoclax-based treatments.

There is a diversity of opinions on how to use MRD testing in multiple myeloma. Being at an academic institution, we use MRD testing routinely at our center to better understand the status of patients at various stages. We use it to help inform prognosis, but also use it to make modifications or changes to therapy as we get results. For us, MRD is one more test we use to help inform clinical practice. We measure MRD for patients who are in complete responses; we have used it in the setting of bispecific and CAR T-cell therapy administration; and we bring MRD into the conversation as we think about stopping therapy.

Many of us use MRD testing in circumstances when patients have achieved a 90% or more reduction in serum paraprotein levels, or very good partial response (VGPR) by international myeloma working group response criteria. Outside of well-designed clinical trials, however, we are not routinely making treatment decisions based on MRD status.

MRD testing is something I occasionally perform in my clinical practice. I see MRD testing as the wave of the future in terms of assessing disease and eventually making treatment decisions based on that information. It is important to start thinking about now, though, so it can be incorporated easily into clinical practice for multiple myeloma.

Right now, MRD testing is not operational at all major academic institutions, but many are using it. For community providers the focus right now should be on preparation for implementation of MRD testing in the clinic.

There are so many different practice patterns. Even within my institution, there are different perspectives. We are outlining MRD algorithms to try to guide our decision making pre- and post-transplant as well as after cellular therapies. In a handful of cases, for our patients that have been on maintenance therapy for 5-10 years and have standard risk disease, we do annual MRD testing to help inform our decision-making. MRD status, however, is not the final deciding factor.

Some protocols such as PETHEMA ALL-AR03 use MRD status to guide treatment plans after achieving morphologic complete remission and to identify patients with good outcomes with chemotherapy alone who may be spared the toxicities of a transplant.

Others have used MRD status during induction to guide treatment intensity with a chemotherapy consolidation and maintenance regimen and to evaluate chemo-minimizing or chemo-free treatment approaches for MRD positive patients.

Multiple clinical trials have shown the prognostic value of MRD at both early and late timepoints. The evidence is strong enough that it may be used as an early surrogate endpoint for survival in clinical trials.

MRD after induction and after consolidation was shown to have significant prognostic value in several clinical trials.

Vidriales and colleagues demonstrated the importance of MRD as a prognostic factor by using MFC to evaluate MRD in adolescents and young adults. A total of 102 individuals with ALL were evaluated, and only patients who were in complete morphologic remission after induction were included. Mandatory MRD evaluation of bone marrow samples was performed by MFC on day 35 and showed that patients with residual blast cells lower than 0.05% had significantly longer RFS than those with levels of 0.05% or higher (42 vs 16 months; P=.001). All patients with MRD greater than 0.1% relapsed within 2 years.¹⁵

The Polish Adult Leukemia Group ALL 4-2002 MRD study also assessed the clinical significance of MRD status after induction in adults with Ph– ALL. The method of MRD quantification used was MFC, which was assessed at the end of induction and consolidation therapy. The endpoint of the study was the prognostic significance of achieving MRD below 0.1% (10-3) after the end of induction and consolidation. MRD was evaluated in 115 of 116 patients in complete remission (CR) after induction and was considered positive (>0.1%), classifying patients as high risk, in 33%.

After consolidation, 21.6% were positive and 42% had at least one positive MRD result at any point in the study. Achieving MRD less than 0.1% after induction was associated with a significant decrease in relapse (26% vs 81%) and improved leukemia-free survival (61% vs 17%) at three years.¹⁶

Serial testing of MRD is recommended and is performed in many centers, although robust trial evidence to substantiate the optimal timing and frequency is not yet available.

The GMALL prospectively evaluated samples from 105 patients who were enrolled in the GMALL 06/99 and 07/03 trials. MRD was performed using RQ-PCR with intervals of 3 months. All patients evaluated were in remission, had completed first-year chemotherapy, and were previously MRD-negative at less than 10^-4.

From the initial 105 patients, 27% converted to MRD positivity, and 61% of those patients relapsed during a median follow-up of 16.1 months. The median time from molecular to clinical relapse was 9.5 months, suggesting an ample window for intervention.

Of the 77 patients who were continuously MRD-negative with quarterly monitoring, only five (6%) relapsed. On the basis of these data, authors suggest suitable times for MRD quantification throughout the course of ALL therapy, with recognition that specific application of MRD quantification depends to some degree on the treatment regimen and patient factors.¹⁷

MRD testing is being used in fixed duration targeted agent trials. The vast majority of Alliance and ECOG studies in CLL are using MRD testing. In addition, there are studies where they are doing MRD-directed duration of treatment assessments. That means if the MRD is negative, patients can stop treatment after a prescribed period of time. If the MRD is positive, some trials are designed to give an additional three to six months of treatment. There has not been a clinical trial that has restarted treatment based solely on MRD positivity without also meeting the International Workshop on Chronic Lymphocytic Leukemia (iwCLL) response criteria.

In new trials that are coming out, especially comparing venetoclax with ibrutinib, MRD is part of the conversation. Previously, we did not have effective enough therapies to get people to MRD negative status. That is really the focus of our research now, though – getting people into these very deep remissions because we have such effective therapies.

For multiple myeloma, there are many clinical trials right now utilizing MRD with some showing encouraging data for results-directed discontinuation of therapy. I think, however, the final word on MRD and how to use it in myeloma is going to come from retrospective analysis of data from many different trials, and how MRD results relate to patient outcomes.

Oncologists/hematologists are leaders of the clinical care team who make treatment decisions to obtain and maintain complete remission in their patients.
Decisions to be made by these individuals including choice of treatment regimen, initial chemotherapy induction and consolidation regimen, referral to transplant center when appropriate, and schedule of bone marrow biopsy and blood testing for MRD markers.

As leaders of the care team, oncologists/hematologists oversee the care provided by advanced practice providers, and they provide education on obtaining and ordering appropriate tests. For example, the teams needs to know that MRD is most sensitive with the first bone aspirate pull.

Patient education about MRD is important, as it can be misconstrued that anything “negative” is bad. Also, patients may be used to getting all of their results via mychart, which may not happen with external labs, so they should know to not be alarmed about this.

Our APPs (NPs and PAs) are usually the ones who perform the bone marrow biopsies. APPs may not be familiar with the specific timing for MRD evaluation.

APPs should be aware that MRD samples should be collected first instead of after the samples for morphology are collected.

Standardized order templates in the EMR are critical to ensure appropriate samples are obtained for MRD at the appropriate time.

Since interventional radiologists do bone marrow biopsies in some institutions, they should be educated about the importance of obtaining MRD from the first bone marrow sample, and you should discuss with them the role of MRD testing in hematologic malignancies.

Pathologists have a critical role in implementing MRD testing, since they understand the nuances of testing as well as the implications for patient care. They ensure laboratory staff are prepared to handle specimens appropriately, validate testing, and coordinate send-out tests.

At institutions where MRD testing is performed in-house, these same pathologists have to interpret the tests and report to/communicate with their oncology colleagues in a timely fashion.

Pathologists play an essential role in MRD testing. In some institutions, they fill the requisition forms for bone marrow biopsies. Pathologists need to have a clear understanding of when to test for MRD and alert the hematologists if they feel MRD is indicated but was not ordered (i.e., at the end of induction in ALL).

In other institutions, pathologists can develop their own guidelines for testing, which allows pathologists to add/modify ordered tests to ensure institutional guidelines are followed.

For an institution developing MRD capabilities, pathologists should be involved in the development and validation of the assays. Once the assays are available, pathologists should be involved in the interpretation and reporting of the assays.

For institutions without MRD capabilities, pathologists should issue an integrated final report that includes the results of all ancillary tests (including MRD assessments) once testing is completed (CAP Guideline for BM reporting). Integrated reporting at diagnosis documents abnormalities and test(s) to follow with MRD testing.

At many institutions, clinical pharmacists work closely with hematologists/oncologists to facilitate treatment with chemotherapy/immunotherapy. Pharmacists have an important role managing toxicities and drug interactions while patients are receiving treatment, but they are often also involved in coordination efforts before a patient begins a new therapy or cycle of therapy.

It is important for pharmacists to be aware of the importance of MRD testing, the implications of positive or negative MRD test results, and where to find these results within their institutional systems.

By proactively reviewing MRD results during their pre-treatment coordination efforts, pharmacists will be able to determine the appropriateness of a given treatment strategy and may be able to identify opportunities for a change in therapy (if needed) that could improve outcomes.

Our Lab Assistants support the collections and ensure all tubes are collected when possible (i.e., unless dry tap and to instruct collection of extra fresh cores for ancillary tests when a dry tap). We have also trained staff in our outreach clinics to ensure all tests have been collected.

In our laboratory, we send our hematology techs to the bedside. If samples are being collected in radiology, our staff assist in the collection and play an important role in making sure the correct tubes are collected. This is especially helpful when different clinicians may not be entirely familiar with all of the tests being performed.

Then our send-out staff handle and ensure the correct tubes are sent for the appropriate testing. Our send-out staff follow processes we have put in place, which includes communicating with the pathologists to confirm orders and how samples should be submitted.

Nurses should be educated on the purpose of MRD testing. Subsequently, they should be able to educate their patients on the importance of testing throughout the patient’s treatment journey. Informing patients prior to specimen collection regarding which tests will be performed and the purpose of each test should be the expectation.

Nurses should maintain a broad understanding of when MRD testing is applicable, how to order MRD testing, when to expect laboratory results, and know how to share those results with the patient.

Nurses should be familiar with their center’s processes for ordering MRD, know what documentation should accompany a sample, know how to handle patient billing issues, and be able to identify resources within the center that can assist with any of these items.

There are numerous roles for administrators in MRD testing.

First, administrators should determine which services the laboratory can provide (e.g., pre-authorization support, patient assistance programs).

Additionally, administrators should provide clinical staff with the resources they need in order to facilitate the testing. This includes:

• Identifying which laboratories your institution will use
• Outlining the ordering process for clinical teams (e.g., providing the requisition with instructions on how to complete)
• Outlining what documentation should accompany the requisition and sample
• Ensuring a process is in place for labeling and collecting samples (e.g., working with the lab for proper labeling and specimen collection)
• Identifying who is responsible for facilitating the send out and how to best handle the MRD results (e.g., faxed paper results that are uploaded into a patient’s EMR vs results amended to a pathology report)

Another key responsibility of an administrator in MRD testing is to ensure insurance coverage and patient responsibility prior to ordering the test. This includes:

• Identifying who is responsible for initiating the authorization and ensuring all key billing aspects are aligned
• Establishing a set process for staff to bring forward patients’ concerns regarding EOB or billing questions
• Working closely with the laboratory that performs MRD testing to identify key personnel within that company (e.g., billing, laboratory leadership, medical director) who can ensure resources are available to patients and staff in order to provide a seamless service

For MRD testing, insurance/billing staff should start with a benefits verification to obtain all possible information on a patient’s insurance coverage.

It is important for insurance/billing staff to be aware of prior authorization and billing for MRD testing.

For example, if there is a Medicare patient who receives MRD testing inpatient, but testing is not tied to the DRG, the patient can have out-of-pocket costs if testing is out of network.

Whether testing is done inpatient or outpatient, in house or send out, it is crucial that staff know if prior authorization is required and the process necessary to obtain it.

It is important for patient advocates to help patients by:

• Reinforcing education on what MRD testing is, how to interpret results, and how results can inform treatment options
• Addressing the potential financial impact of MRD testing (e.g., required preauthorization, out-of-pocket costs)
• Helping mitigate potential financial impact of MRD testing (i.e., connect patients to financial assistance programs)
• Advocating for an institutional policy that makes MRD testing for patients more readily available
• Advocating for processes that ensure communication among financial department/billing/pre-auth/providers/lab to ensure the financial impact on patients is accounted for in the standard operating procedures
• Advocating for state/national policies that include insurance coverage for MRD testing and limit out-of-pocket expenses for patients

MRD POSITIVE

When MRD is positive after induction, consider changing therapy (e.g., blinatumomab vs. clinical trial vs. transplant). If MRD is positive, one of the most important things to consider is whether the patient should be referred to a transplant center for evaluation (which would probably also lead to evaluation for clinical trials).

MRD NEGATIVE

Achieving an MRD-negative status of less than 10^-4 within the first two to three cycles of induction/consolidation therapy is a critical milestone that should be pursued in all patients with ALL. It correlates with improvement in relapse-free survival and lack of benefit from transplant.

GRAALL (Group for Research on Adult Acute Lymphoblastic Leukemia) retrospectively analyzed transplant outcomes in patients who were treated in the GRAALL 2003 (Feasibility of Risk-Adapted Therapy in Young Adult Acute Lymphoblastic Leukemia: a Multicenter Trial) and GRAALL 2005 (Treatment of Acute Lymphoblastic Leukemia in Younger Adults) trials, which assessed the use of pediatric-inspired chemotherapy in adults with ALL.

A total of 282 patients who received a transplant in first CR (CR1) were included. All patients were considered high-risk. Quantitative PCR–based MRD evaluation was performed six weeks after induction initiation and after the three blocks of consolidation (12 weeks after induction).

The three-year post-transplant nonrelapse mortality was 15.5%, and survival was almost 70%. Good MRD response, defined as MRD less than 10^-3 after the first induction, was not associated with benefit from transplant.¹⁸

The more we use venetoclax in our regimens, whether it is in combination with an anti-CD20 monoclonal antibody or other combinations, and talk about fixed duration therapies, providers need to understand the role of MRD, including how and when to monitor MRD, and how MRD status should be used to inform next steps.

With the uptake of venetoclax-obinutuzumab (based on results of the CLL14 trial), I could see obtaining MRD status at the end of treatment. Based on the data that is coming out in high-risk patients (e.g., IGHV-unmutated, TP53 mutations & Del(17p), and complex karyotype), these individuals have been shown to lose MRD status quicker compared to standard risk patients and should also be considered for testing. Considering both of these populations, I can definitely see the utility of testing in high-risk patients receiving venetoclax-obinutuzumab therapy.

MRD testing is nearly universally done in clinical trials and we are trying to figure out how to move the impact of and the clinical relevance of this testing into practice. At our practice, however, we are not yet performing MRD testing on everyone and have not begun to alter treatment decisions based on MRD status.

In each of our practices we have patients termed “exceptional responders” who have been in a serologic complete remission for >10 years. The current practice is to continue maintenance therapy to maintain the remission, as the data it is not clear for us to stop therapy and observe, or to continue. Results of ongoing studies will shed light on this dilemma.

For patients who are in a long-term complete response, we can monitor MRD and want to provide that information. We do not use MRD today as the sole determinant variable, but as one more test to inform decision-making. If I have a patient who is in a complete response and has sustained MRD negativity, and they come to clinic and say, ‘Listen, I have tremendous fatigue. I have diarrhea.’ Then, I am a little more comfortable saying, ‘let’s stop therapy.’ On the other hand, if a patient is MRD positive, and doing great on therapy, then that is another reason to keep going a little longer.

I explain to patients, this is a piece of the puzzle, so we obtain MRD on everyone who is willing to undergo a bone marrow biopsy to test MRD status. It is another tool to help decision-making. We do a lot of shared decision-making at my organization where the patient, providers, and caregivers all sit together and decide on the best next step. MRD status can be so helpful when having a conversation on whether to stop or continue therapy.

I think as we continue to learn more about MRD, the medical team will play a key role in capturing MRD and working with centers to coordinate care and establish follow-up. It is important for physicians to become familiarized with MRD testing, have conversations with referral centers where their patients are receiving stem cell transplants, and understand the role of MRD in medical decision-making.

For patients on cellular therapies, we are still in discussions on if/how we are going to use MRD testing.

At my institution, we are routinely checking MRD on most of our patients with multiple myeloma. Amongst all seven multiple myeloma providers, though, we are not necessarily standardly using results to inform treatment decision-making. We still have a way to go before we reach consensus as a practice.

It is important to determine what standard operating procedures you need to have in place. Standard operating procedures can also be used to help train staff before MRD testing is implemented.

We developed order sets for bone marrow biopsies on ALL and AML patients (newly diagnosed and relapsed) in collaboration with our hematopathologists. These were distributed to pathology and to our fellows and faculty.

Newly diagnosed ALL patients: Order Flow cytometry, cytogenetics, FISH for BCR/ABL and MLL gene rearrangement, Foundation one Hem and ID testing (clonoSEQ®). On day 30 BM BX: Order Flow cytometry, cytogenetics, clonoSEQ® for MRD. In addition, if patient had positive BCR/ABL, then repeat PCR for BCR/ABL on BMBX on day 30.

In our EMR, we have a check box for MRD testing. When we select that box, it gives us the option for clonality testing, which is done at the time of diagnosis or measurable residual disease, which is done at follow-up.

It is the clinician’s responsibility to put in the order. Once the order is placed, the patient receives a print form. The patient then takes the form to the procedure team, where testing is done. The team uses the form to know what to collect. The sample is then sent to pathology for them to send out the sample for testing.

We do not have order sets. Our EMR is not that flexible in terms of ordering. When the hematologists want to order a MRD test, they put a comment in the EMR, which serves as our check box.

Then that comment triggers the process we have put in place, which includes reserving one of the tubes for MRD testing. So that is how our institution has approached it.

Routine testing for critical genomic aberrations tends to get missed in the community oncology setting, so I worked with our pathology department to design a standardized order set. In our patients, it is imperative that we are routinely testing for IGHV mutational status, TP53, and chromosome 17p. MRD testing in CLL is another way of being able to appropriately monitor the trajectory of our patient’s disease. Below is the order set we created to make sure critical labs are captured, with the potential to add-on MRD when appropriate.

CLL Work-up for diagnosis

Our institution has developed a set of standard guidelines and algorithms for both diagnosis and follow-up in collaboration with our oncologists and pathologists, which is continuously updated in the context of NCCN guidelines, literature, and tests offered at our reference laboratory.

Our standard bone marrow collection set (two Heparin tubes [for flow cytometry and cytogenetic tests] and two-three EDTA tubes [for molecular tests]), in addition to samples for morphology, ensure we have samples for all tests that may be needed for complete evaluation at diagnosis and follow-up.

These algorithms are critical to ensuring correct WHO subclassification at diagnosis and identification of cytogenetic and molecular abnormalities for disease monitoring. They are also designed to be cost effective.

Our reference laboratory has been a critical partner in ensuring tests performed at diagnosis are reported in a timely manner, especially FISH for t(9;22) BCR/ABL1 (24-48 hour turn-around time) and CRLF2, since these results determine which tests are added.

Additionally, our administrative staff and EMR are critical in ensuring that the pathologist reviewing the case receives the results of all tests as soon as they are available.

Our initial workup includes:

• Flow cytometry including evaluation for CRLF2
• Chromosome analysis
• STAT FISH for t(9;22) BCR ABL1
• DNA and RNA extraction and storage

If CRLF2 is positive, we send FISH for CRLF2. If FISH for t(9;22) BCR/ABL1 is positive, we send RNA for BCR/ABL1 (if it was not ordered upfront).

If FISH is negative for BCR/ABL1 and CRLF2, we send additional studies (cytogenomic SNP microarray, ALL FISH panel, PH-like FISH panel) to evaluate for other recurrent abnormalities and for Ph-like B-ALL.

Extracted DNA is reserved if additional studies (i.e., NGS) are needed to further characterize the clone for monitoring or subclassification.

We do not automatically send samples out. Right now, we wait for our pathology report to come back, which is usually within two days of a specimen being obtained. It took many months to create an algorithm, which covers several blood cancers. We came to consensus that if the pathology report is negative, we will then send the specimen out for additional molecular testing. 

clonoSEQ®

*Indications

clonoSEQ® sent on BM only if

• ALL (B or T) pre-transplant/CAR-T or post (30d, 100d, 180d, 365d) or
• MM pre-transplant or post (100d, 1y, 2y) with VGPR or better

clonoSEQ® sent on PB only if

• NHL or DLBCL pre-transplant/CAR-T or post (30d, 100d, 180d, 365d)

Our lab requisition is our standard bone marrow requisition. We have been really thoughtful in making sure that every test that can be ordered for a bone marrow is there.

We also include a statement that pathologists may add/modify tests. We also have a standard set of tubes that are always collected with every bone marrow. We put a lot of the onus on our clinicians to order the appropriate MRD tests.

Our clinicians follow our standard institutional document that outlines testing for each disease type, but they also make decisions based on what we know about the patient from before.

In our lab, what has been really successful for us is the creation of a standard collection set. For every patient who has a bone marrow biopsy, a sample is collected for flow cytometry, cytogenetic tests, and molecular tests, if those are indicated. For an anticipated diagnosis of acute leukemia, we recommend collection of an extra EDTA tube for any additional testing or to extract DNA and RNA.

For example, in new B-cell ALL patients, we always do RNA extraction and rearrangement that can be monitored by RT-PCR methodology (i.e., BCR/ABL1) and we send the extracted RNA to document fusion transcript and size for monitoring. Extracted DNA can be used to document a clone in NGS-based tests, or for further molecular characterization of the clone. A standard collection set is critical and must be integrated into the EMR.

It is important to use the first low volume pull of bone marrow aspirate sample for MRD assessment to avoid hemodilution and allow for more accurate results.

Patient education is crucial, but many times this information can be a lot to take in. So it is important to identify a trusted caregiver, partner/spouse, or family member who can help the patient process this information.