Myeloma Survival Unchanged With Longer Lenalidomide

Survival did not improve with indefinite treatment

Continuing lenalidomide maintenance until progression did not extend overall survival compared with a fixed 2-year course in ENDURANCE, a randomized study of newly diagnosed, standard-risk multiple myeloma managed without an intended upfront autologous stem-cell transplant. The result challenges the assumption that longer maintenance must translate into longer life.

The survival finding does not mean that duration was irrelevant. Indefinite treatment prolonged progression-free survival, while exposing patients to more cumulative therapy and a higher burden of second primary malignancies. That trade-off is central to interpreting the trial: treatment delayed progression, but the additional disease control did not produce a detectable survival advantage at 7 years.

For practice, the data strengthen the case for a planned discussion about stopping maintenance after 2 years. They do not establish that every eligible patient should stop, nor do they prove that the two strategies are equivalent. A nonsignificant overall-survival result can reflect a genuinely small effect, effective treatment after progression, competing causes of death or insufficient statistical precision to exclude a clinically meaningful difference.

These outcomes should be considered together rather than ranked automatically. Progression-free survival matters, particularly when relapse may cause organ damage or require intensive treatment. Overall survival, however, is the most consequential endpoint when deciding whether prolonged exposure is justified. Second cancers, adverse effects, monitoring, financial toxicity and years spent taking therapy also matter to patients even when they are not captured by a single efficacy measure.

How ENDURANCE tested maintenance duration

ENDURANCE was a randomized cooperative-group trial that enrolled 1,087 patients with newly diagnosed multiple myeloma. Its initial treatment comparison evaluated carfilzomib, lenalidomide and dexamethasone against bortezomib, lenalidomide and dexamethasone. Eligible participants then entered a second randomization comparing lenalidomide maintenance for 2 years with lenalidomide continued until disease progression, unacceptable toxicity or another reason for discontinuation.

The design is especially relevant to US patients with standard-risk disease for whom immediate transplantation was not planned. It does not address maintenance after upfront autologous transplantation, and it should not be extrapolated directly to high-risk cytogenetic disease. Those populations can have different relapse dynamics and may receive different maintenance strategies.

Random allocation supports a causal interpretation of differences between the maintenance policies among participants who entered that comparison. At approximately 7 years, indefinite maintenance had not produced a statistically significant overall-survival benefit. Progression-free survival favored continued treatment, but second primary malignancies were more frequent with longer exposure.

The distinction between the trial’s two randomizations is important. The maintenance result is not simply an observational comparison between patients who happened to remain on lenalidomide and those who stopped early. It evaluates two planned duration strategies. Conversely, the analysis applies to patients who remained eligible for maintenance randomization after initial therapy, not necessarily to every person enrolled at diagnosis.

A fixed stop is supportable, not compulsory

The findings support fixed-duration lenalidomide as a reasonable option for appropriately selected patients who resemble the ENDURANCE population. Until now, continuing maintenance until progression has often been favored because earlier progression-free survival gains were interpreted as sufficient justification for ongoing therapy. ENDURANCE supplies randomized evidence that a defined stopping point can preserve long-term survival despite an earlier average time to progression.

That can change the clinical conversation. Rather than treating indefinite therapy as the default that requires justification to stop, clinicians and patients can weigh two evidence-based priorities: maximizing the first remission or limiting cumulative exposure without a demonstrated survival penalty at the reported follow-up.

The balance will not be identical for everyone. A patient tolerating lenalidomide well and strongly prioritizing delayed relapse may reasonably value the progression-free survival advantage. Another patient may give greater weight to chronic adverse effects, second-cancer risk, monitoring, cost, reproductive precautions or freedom from continuous treatment. ENDURANCE informs that choice; it does not replace it.

The second-primary-malignancy signal deserves proportionate attention. It should not be interpreted as meaning that most patients receiving prolonged lenalidomide will develop another cancer. It does show that additional years of exposure are not biologically or clinically neutral. Absolute risk, cancer type, latency and competing myeloma risk are necessary context when counseling patients and when health systems assess the value of indefinite maintenance.

Policy implications are also plausible. Pathways and coverage rules should allow fixed-duration maintenance when it is aligned with patient preference and standard-risk biology, rather than treating discontinuation at 2 years as undertreatment. At the same time, the trial does not justify an inflexible coverage limit that removes access to continued therapy for patients who prioritize disease control.

Important uncertainties remain

The absence of an overall-survival difference is not proof of identical survival. ENDURANCE was designed to test treatment strategies, but the precision of the reported estimate and the number of deaths determine how confidently modest benefit or harm can be excluded. Longer follow-up may also alter the balance if progression, later-line treatment or second malignancies affect mortality after year 7.

Post-progression therapy can dilute an overall-survival difference. Patients assigned to stop lenalidomide may respond to treatment at relapse, while those treated indefinitely may have different resistance patterns or later treatment options. Such effects are part of a real-world treatment strategy, but they complicate efforts to attribute survival solely to the maintenance period.

Generalizability is another limitation. The trial focused on standard-risk disease without intended upfront transplantation and began before some current induction, antibody-based and measurable-residual-disease-guided approaches became routine. It therefore cannot determine the ideal maintenance duration after modern quadruplet induction, in high-risk myeloma, after transplantation or when treatment decisions are adapted to serial residual-disease testing.

Finally, progression-free survival and second primary malignancies should be interpreted with competing risks and treatment discontinuation in mind. Duration assigned is not always duration received. Toxicity, patient choice and progression can reduce exposure in the indefinite group, while events occurring after the fixed stop may still reflect prior treatment.

Questions clinicians ask

Does ENDURANCE establish 2 years as the new standard duration?

No. It supports 2-year maintenance as a reasonable option for standard-risk patients managed without upfront transplant because indefinite therapy did not improve 7-year overall survival. The study was not an equivalence mandate, and duration should still reflect relapse risk, tolerance, patient priorities and the limits of generalizing the trial to newer regimens.

Is progression-free survival still clinically meaningful without a survival gain?

Yes. Delaying progression can postpone symptoms, organ injury and the need for another treatment. But the value of that delay must be balanced against continuous therapy, cumulative toxicity, cost and second primary malignancies, particularly when the randomized comparison has not shown that longer maintenance helps patients live longer.

Should these results change maintenance after upfront transplantation?

Not directly. ENDURANCE studied patients for whom immediate transplantation was not intended, so its duration comparison should not be assumed to apply after autologous stem-cell transplantation. Post-transplant decisions require evidence from that setting, especially for patients with high-risk cytogenetics or those receiving combination maintenance.

Does the second-cancer finding mean lenalidomide should routinely be stopped?

No. The signal is one component of the benefit-risk assessment, not a reason for automatic discontinuation. It becomes more relevant when indefinite therapy offers longer progression-free survival without a demonstrated overall-survival gain, making cumulative exposure and the patient’s tolerance for competing risks central to shared decision-making.

References

1. Indefinite versus Fixed-Duration Lenalidomide Maintenance in Multiple Myeloma — New England Journal of Medicine, 2026
2. Carfilzomib, Lenalidomide, and Dexamethasone Versus Bortezomib, Lenalidomide, and Dexamethasone for Patients With Newly Diagnosed Multiple Myeloma Without Intention for Immediate Autologous Stem-Cell Transplantation (ENDURANCE) — The Lancet Oncology, 2020
3. Bortezomib or Carfilzomib With Lenalidomide and Dexamethasone in Treating Patients With Newly Diagnosed Multiple Myeloma — ClinicalTrials.gov, 2013