For more than 10 years, ongoing treatment with lenalidomide following autologous hematopoietic stem cell transplantation (ASCT) has been the unchallenged gold standard.
The new findings were from the MASTER study, published in The Lancet Haematology, along with an invited commentary by Dr. Derman. In MASTER, patients who showed no evidence of disease after transplantation and two phases of consolidation therapy had the opportunity to avoid lenalidomide maintenance.
In the lenalidomide-free group, just 9% of patients without high-risk chromosome abnormalities or just one HRCA progressed within 2 years. About 47% of patients with two or more HRCAs progressed within 2 years.
The MASTER authors concluded that modern regimens of induction plus ASCT/consolidation might be good enough for many patients. Avoiding maintenance therapy “lead to most patients with newly diagnosed multiple myeloma reaching an MRD [minimal residual disease]-free, treatment-free state with a low risk of disease progression.” They also cautioned that the approach was “not optimal” for high-risk patients.
“We have been indoctrinated into continuous therapy,” said lead author Luciano Costa, MD, professor of medicine at the University of Alabama at Birmingham. “This was a reasonable approach at the time when [induction and consolidation] therapy was not as effective.”
Lenalidomide for post-ASCT maintenance became a guideline standard following a pivotal study published in the New England Journal of Medicine in 2012. The study showed that lenalidomide maintenance after transplantation almost doubled the time to progression (P < .001) and improved survival (P = .03).
Shaji Kumar, MD, is chair of the National Comprehensive Cancer Network Multiple Myeloma Guidelines and professor of medicine at the Mayo Clinic in Rochester, Minn.
Dr. Kumar said that the MASTER results alone are not sufficient to change current guidelines because the study was a single-arm, uncontrolled, phase 2 trial. However, there are “multiple reasons why we would like to stop treatment at some point in time,” Dr. Kumar said.
“Quality of life, the financial cost, and the toxicity are three main reasons why we would like to discontinue the maintenance or give maintenance only for the amount of time that a patient needs it,” Dr. Kumar added. “So then the question comes up, how do we identify the people who need long term treatment versus the people who don’t?”
“Response” in MM is conventionally classified by criteria laid down by the International Myeloma Working Group. However, the MASTER trial made use of a different measure: MRD negativity, in which myeloma cells can no longer be detected in bone-marrow aspirate at a level of 1 in 100,000 (10–5) or, in some studies, 1 in 1 million (10–6).
MRD is a rare bird in oncology: A surrogate endpoint that provides answers faster than progression-free survival or overall survival but is a reliable guide to both. In 2020 a team headed by Nikhil Munshi, MD, professor of medicine at Harvard Medical School, Boston, published a large meta-analysis showing that a negative MRD in a patient with MM was significantly prognostic for both progression-free survival (hazard ratio, 0.33; P < .001) and overall survival (HR, 0.45; P < .001).
In an interview from 2022, Dr. Munshi explained that patients with MRD negativity are not necessarily “cured”: “Simply, physiologically, it means that if a patient has one [myeloma] cell in a million, that cell is going to take a much longer time to grow up to be myeloma.”
In MASTER, which was based at five U.S. academic medical centers, 81% of participants (96/118) achieved MRD negativity at the 10–5 cutoff. Eighty-four people (71%) had two consecutive MRD-negative results and did not go on to lenalidomide maintenance. Instead, they were monitored with lab tests every 8 weeks for the first 24 weeks and every 16 weeks thereafter and assessed for any changes in MRD after 6 months and 18 months.
The median age in MASTER was 61 years, 43% were women, and 20% were non-Hispanic Black. About 20% of participants had two or more HRCAs, 37% had one HRCA, and 43% had no HRCAs. All participants had four 28-day cycles of induction with Dara-KRd (daratumumab, carfilzomib, lenalidomide, and dexamethasone). This was followed by ASCT and up to two phases of consolidation with Dara-KRd.
MASTER is not the only study to show that MRD-guided discontinuation of lenalidomide seems feasible in some patients. In November 2023, Spanish researchers published a study in Blood testing a combination of lenalidomide, dexamethasone, and ixazomib. The trial allowed MRD-negative patients to stop therapy after 2 years. Progression was 17.2% over the following 4 years in the group that dropped maintenance, which included high-risk patients. The authors concluded that their results “support the safety of maintenance therapy discontinuation in patients with negative MRD at 2 years.”
These two trials are conspicuous by their rarity.
Said Dr. Derman: “We haven’t done a great job until recently of designing trials that look into discontinuation.”
Both Dr. Derman and Dr. Costa raised the elephant in the room: industry funding.
“Maintenance therapy is big business,” said Dr. Derman. He added that he had experienced problems in the past obtaining industry funding for research that involved stopping therapy.
Dr. Costa, coauthor of the MASTER trial, agreed in part: “Most pharmaceutical companies do not embark on trials like this because they’re primarily doing registration trials.” MASTER garnered some industry funding, however, and Dr. Costa found that encouraging.
How much money is at stake? In other words, what are the financial savings if patients with zero to one HRCAs who are MRD negative start to take treatment holidays from lenalidomide maintenance?
In the United States in 2019 approximately 6,410 patients received ASCT. The MASTER publication stated that “around 85%” of newly diagnosed MM patients have zero to one HRCAs and that 73% of these patients were able to stop therapy in the trial. This suggests that, each year, approximately 4,000 new patients might be eligible to avoid lenalidomide after ASCT.
The price tag of lenalidomide is approximately $20,000 per month in the United States, according to Dr. Derman. A cohort of 4,000 patients avoiding lenalidomide each year represents lost revenue of $80 million per month or almost $1 billion per year. And this does not take into account patients already on lenalidomide from previous years – or sales outside the United States. The MM multiple research pipeline reflects a lack of enthusiasm for paring down maintenance.
There are currently 229 interventional clinical studies in MM taking place nationwide. Of these, just three trials are testing what happens when patients stop therapy in the post-ASCT setting and none of the three is sponsored by industry (NCT04108624, NCT05091372, and NCT04071457). (All data from clinicaltrials.gov; search covered phase 2, 3, or 4 studies still accruing data; descriptions hand-checked; search terms: maintenance/consolidation/post-ASCT.)
Dr. Derman said that it is “incumbent on investigators” to carry out the studies to identify who is eligible to stop therapy because industry is “probably always going to err on the side of treating more.”
Sergio Giralt, MD, head of the adult bone marrow transplant service at Memorial Sloan Kettering Cancer Center, New York, was an author of the key 2012 study that enshrined lenalidomide maintenance in the guidelines. Dr. Giralt expressed concerns about the single-arm design of MASTER and said he would like to see a randomized study where some patients continued treatment and others stopped.
Dr. Giralt cautioned: “If you’re MRD negative, the chances of having to deal with your disease in the next 5 years is one in five.” Physicians could certainly “have a conversation” with patients who are MRD negative about stopping therapy, but this would need to be weighed against the need for bone-marrow biopsies every 3-6 months to check progress. (In MASTER, MRD was checked at 6 and 18 months.)
Dr. Kumar believes that “we need to pursue the concept of decreasing the duration of treatment.” However, newer immunotherapies may be the answer: “Who knows? That may be the future, that we will do more of this hit-and-run approach rather than trying to keep them persistently on something.”
Dr. Derman said: “I personally think that the data is already there ... [MASTER] shows that perhaps this notion of indefinite maintenance therapy is one that really has to go by the wayside ... patients should have the option to consider with their physician [the chance to] potentially discontinue treatment.”
For 15 years, relentless lenalidomide maintenance has “quite rightly been the strongest pillar of therapy”, said Dr. Costa. “But for patients, this is not something that they easily embrace – it’s not ideal that you are going to have to take therapy for the rest of your life.”
Dr. Costa concluded: “I don’t think we had a single patient who was reluctant to stop therapy.”
Dr. Munshi reported relationships with Adaptive, Abbvie, Amgen, Bristol-Myers Squibb, Celgene, Janssen, Karyopharm, Legend, Millennium, Novartis, Pfizer, and he is the scientific founder of Oncopep and DCT. Dr. Derman disclosed ties with Janssen, Cota, and BMS. Dr. Costa reported ties with Amgen, Cota, Janssen, BMS, AbbVie, Ionis, Genentech, Sanofi, Karyopharm, AstraZeneca, Adaptive Biotechnologies, Takeda, and Pfizer. Dr. Kumar declared relationships with AbbVie, Amgen, BMS, GlaxoSmithKline, Karyopharm, Regeneron, Roche, Sanofi, Takeda, and BeiGene. Dr. Giralt reported ties with Amgen, CSL Behring, Caladrius, Celgene, Ceramedix, ExpertConnect, GlaxoSmithKline, Janssen, Karyopharm, Kite Pharmaceuticals, Magnolia Innovation, Novartis, Omeros, Pfizer, Physicians’ Education Resource, Sanofi, TRM Oncology, and Xcenda.