When treating extramedullary disease (EMD), intravenous (IV) bortezomib should be used over the more common subcutaneous formulation. The higher peak drug concentration (Cmax) achieved with IV administration is critical for efficacy against these difficult-to-penetrate sanctuary sites.
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.
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.
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.
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.
Clinicians must maintain high suspicion for extramedullary disease (EMD). It can present atypically, like a plasmacytoma mimicking a sinus infection. Critically, new EMD deposits can appear even when a patient's monoclonal protein and light chain levels are stable, making imaging and symptom-based suspicion vital.
The Determination II trial chose isatuximab over daratumumab for its induction regimen based on two factors. First, it may have an edge in high-risk myeloma (1q amplified). Second, its less frequent dosing schedule (weekly for one month) reduces the myelosuppression seen when combining iberdomide with daratumumab.
CELMoDs are being actively trialed as a maintenance therapy after CAR T-cell treatment. The strategy is to leverage the CELMoDs' ability to enhance T-cell function and upregulate effector T-cells to boost the activity and persistence of the CAR-T product, potentially leading to more durable responses and preventing relapse.
The DETERMINATION trial found that African American patients, who are often Duffy null, had better outcomes with RVD alone versus early transplant. The Duffy null phenotype reduces the ability to absorb inflammatory stress, suggesting that pro-inflammatory treatments like high-dose chemotherapy and transplant may be less advantageous for this population.