Unlike IMiDs, which only partially engage the target, CELMoDs like iberdomide are larger molecules that fully close the cereblon E3 ligase pocket. This maximizes degradation of target proteins Ikaros and Aiolos, leading to greater potency and what is described as "hitting the death star" of the myeloma cell.
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BTK degraders work despite most kinase inhibitor resistance mutations. However, resistance to degraders themselves alters the BTK binding pocket so significantly that subsequent targeting with any BTK kinase inhibitor is unlikely to be effective, positioning them as a potential end-of-line therapy.
Terns' CML drug is an allosteric inhibitor, targeting a different site on the target protein than older drugs. This mechanism provides greater selectivity, avoiding off-target effects like arterial blockages common with active-site inhibitors. This technical advantage creates a compelling safety and tolerability profile, a key differentiator in a market with established therapies.
Lenalidomide has a unique off-target effect on C1K alpha which clonally selects for p53 mutated cells, increasing second cancer risk. Preclinical data clearly show that CELMoDs like iberdomide and mezigdomide do not share this mechanism, offering a significant potential safety advantage over the older IMiD.
The degradation mechanism is fundamentally superior to inhibition because it removes the entire protein, addressing both its enzymatic and scaffolding functions. This allows degraders to hit targets harder and more completely, suggesting they could become the dominant modality across oncology and other therapeutic areas.
Unlike older IMiDs where T-cell effects are secondary, CELMoDs have a powerful, independent pro-T-cell mechanism. This dual action is so significant that in the future, CELMoDs will be prescribed not just for their direct anti-myeloma effects, but specifically to enhance the efficacy of T-cell therapies like CAR-T and bispecific antibodies.
An expert who initially viewed CELMoDs as incremental improvements now considers them fundamentally different. The new litmus test for future myeloma trials will be tracking prior patient exposure to CELMoDs like iberdomide, just as they track prior IMiD exposure today, cementing their status as a distinct therapeutic category.
Traditional targeted cancer therapies inhibit or 'cool down' overactive pathways, like pumping brakes on a runaway car. Delpha Therapeutics employs a counterintuitive 'activation lethality' approach, further over-activating pathways to 'overheat the engine' and cause catastrophic failure in cancer cells—a fundamentally opposite but highly effective strategy.
During the pandemic, a multicenter mezigdomide trial had zero COVID-19 deaths. This contrasts sharply with bispecific antibody trials in similar populations, which reported significant COVID mortality. This suggests CELMoDs have a more favorable immune profile for managing viral infections in immunocompromised patients.
A single degrader molecule can destroy thousands of target proteins per hour, a massive improvement over the 1-to-1 stoichiometry of traditional inhibitors. This extreme potency makes them ideal payloads for Degrader-Antibody Conjugates (DACs), combining the precision of antibodies with the power of catalytic degradation.
Mezigdomide is considered one of the most active oral agents against extramedullary disease (EMD). Its molecular structure was specifically engineered to optimize tissue penetration, addressing a significant clinical challenge where myeloma grows outside the bone marrow in heavily pretreated patients.