Another Post-Lenalidomide Myeloma Sequencing Option
- SUCCESSOR-2 reflects a broader shift in multiple myeloma, where sequencing strategy is becoming as important as individual drug activity.
- The study evaluates whether deeper cereblon pathway modulation with mezigdomide can overcome or extend beyond lenalidomide resistance in relapsed/refractory disease.
- Additional positive data could position CELMoDs earlier in the treatment algorithm as practical, off-the-shelf post-lenalidomide backbone therapies before CAR T or bispecific antibodies.
- The trial highlights the growing tension between highly effective but resource-intensive cellular therapies and scalable combination regimens that can be delivered broadly in routine practice.
- Beyond efficacy alone, SUCCESSOR-2 may ultimately help define how clinicians sequence immune-based therapies across the increasingly complex modern myeloma landscape.
- The SUCCESSOR-2 trial achieved a median PFS of 18 months without disease progression, compared with 8.3 months in the standard group, more than doubling the PFS.
The phase 3 SUCCESSOR-2 trial evaluates whether adding the next-generation CELMoD agent mezigdomide to carfilzomib and dexamethasone improves outcomes for patients with relapsed/refractory (R/R) multiple myeloma previously exposed to both lenalidomide and anti-CD38 therapy. While the primary endpoint is progression-free survival (PFS), the broader significance of the study lies in its potential to inform sequencing strategy in an increasingly complex therapeutic landscape.
Presented at ASCO 2026, SUCCESSOR-2 became the first randomized phase 3 trial to report positive results for a mezigdomide-based regimen in R/R multiple myeloma. Principal investigator Dr. Paul Richardson, of Dana-Farber Cancer Institute, notes that the study demonstrated a median PFS of approximately 18 months with mezigdomide, carfilzomib, and dexamethasone compared with roughly 8 months in the control arm – more than doubling the PFS.
Notably, among patients treated at first relapse, median PFS had not yet been reached.
“The findings are really quite remarkable and very encouraging,” Dr. Richardson tells SurvivorNet Connect.
SUCCESSOR-2 is testing whether deeper cereblon pathway modulation can restore or enhance immune-mediated sensitivity in patients with prior IMiD exposure. Mezigdomide is designed to overcome resistance pathways that limit the durability of earlier IMiDs. CELMoDs are increasingly viewed not as incremental additions, but as a deliberate effort to preserve and intensify cereblon biology after lenalidomide resistance develops.
Dr. Richardson emphasizes that mezigdomide’s potential extends beyond direct anti-myeloma activity.
“What we know is that mezigdomide is not immune exhausting. It’s the opposite. It enhances immune activation, enhances T cells, and enhances natural killer cells,” he explains. That observation may prove particularly relevant as clinicians increasingly think about sequencing therapies across multiple lines of treatment rather than evaluating individual regimens in isolation.
The Sequencing Question
If SUCCESSOR-2 demontrates a meaningful and durable PFS benefit with longer follow-up, the implications for sequencing could be substantial. CELMoDs may emerge not as late salvage options, but as earlier post-lenalidomide backbone therapies capable of extending disease control before patients transition to CAR T-cell therapy, bispecific antibodies, or other immune-based approaches. This positioning could meaningfully influence where clinicians place T-cell therapies in the treatment algorithm.
“While the treatment landscape is getting broader almost every month, there is still a huge need for improvement,” Dr. Luciano Costa, of UAB O’Neal Cancer Center in Birmingham, Alabama, says. “Many new therapies can be challenge to administer or to tolerate, at least for some patients. Most patients will go on to receive different therapies in sequence and ultimately need access to newer drugs. But perhaps most importantly, is that immunotherapy, either CAR T or T-cell engagers, do not compete with, but rather complement the role of CELMoDs.
“We … are busy refining how we can benefit from the immunostimulatory effects of CELMoDs to improve the efficacy and safety of immunotherapy. That is one of the most promising areas for clinical research in multiple myeloma right now,” he adds.
The study also reflects a broader tension in balancing highly effective but resource-intensive cellular therapies with off-the-shelf combination regimens that can be delivered continuously in routine practice. Although CAR T and bispecific antibodies have transformed outcomes, access limitations, logistical complexity, and toxicity management remain significant real-world constraints.
A Potential ‘Off-The-Shelf’ Option
This theme was reinforced throughout ASCO 2026, where new data from bispecific antibody studies such as MajesTEC-9 and ongoing advances in CAR T therapy highlighted both the promise and complexity of immune-based treatment strategies.
Dr. Richardson cautions against viewing these modalities as competing approaches, noting that “we need every option we have and we need all hands to the pumps” to address the heterogeneity of relapsed myeloma. In this setting, a regimen such as Mezi-KD may be particularly attractive if it delivers comparable depth and durability of response with more immediate and scalable administration.
“What I love about mezigdomide is it’s truly off the shelf,” Dr. Richardson explains. “It is a pill. You can write that prescription and your patient can start treatment right away.”
Tolerability and treatment durability will also be central to its clinical relevance. If mezigdomide demonstrates manageable long-term toxicity alongside durable disease control, it may serve as a practical, off-the-shelf bridge strategy that delays or optimally sequences the need for more intensive immune effector therapies such as CAR T or bispecific antibodies.
Side Effects
At ASCO 2026, investigators reported that neutropenia was the primary toxicity associated with mezigdomide-based therapy, while opportunistic infections remained uncommon and treatment-related mortality was low.
“The only side effect that was of note was neutropenia,” Dr. Richardson notes. “As hematologists, that’s stock and trade. We could manage that.” Such findings may prove important if clinicians seek therapies capable of providing durable disease control without the logistical and toxicity burdens associated with some cellular and immune-based approaches.
SUCCESSOR-2 is less about redefining cereblon biology and more about expanding the post-lenalidomide treatment options and adding another effective, readily deployable sequencing option in a disease where optimal treatment order is becoming as important as individual drug activity.
UH Seidman Cancer Center’s Dr Timothy O’Brien, an expert in the treatment of multiple myeloma, added that questions remain, saying, “[It is] not clear at the moment where CeLMoDs fit in a very crowded field of exciting new treatment options which include CAR T and bispecifics.”
Dr. Richardson notes, the growing number of effective therapies is not evidence of a crowded field but rather a reflection of the need for multiple treatment pathways. “We need lots of options for our patients,” he says. “The very good news is that at this year’s ASCO, we’ve heard about multiple options and continued momentum toward providing our patients with better outcomes.”
