Incidence of second primary malignancies in patients with multiple myeloma receiving anti-CD38 monoclonal antibodies: A systematic review and meta-analysis

Anti-CD38 monoclonal antibodies (mAbs) are commonly used for treating newly diagnosed and relapsed/refractory (r/r) multiple myeloma (MM). However, concerns have been raised about the occurrence of second primary malignancies (SPMs) in patients receiving anti-CD38 mAbs. Assessing the safety data for rare adverse events like SPMs is challenging because individual clinical trials are typically focused on the primary endpoint. Therefore, we conducted a meta-analysis of randomized controlled trials (RCTs) published between January 2005 and April 2022, including patients with newly diagnosed or r/r MM. Our aim was to compare SPM rate with the use of anti-CD38 mAb-based regimens with other anti-myeloma regimens. After a median follow-up of 35.3 months (range: 8.2-56.2), we found that exposure to anti-CD38 mAbs was associated with an increased risk of developing SPMs compared to the control group (6.8% vs. 5.2%; Peto odds ratio [OR]: 1.53 [95% confidence interval (CI): 1.20-1.95]; I2= 0%, p-value for heterogeneity= 0.44). This increased risk was primarily driven by non-melanoma cutaneous cancers (92 vs. 47; Peto OR: 1.77 [95% CI: 1.25-2.51]; I2 = 0%, p-value for heterogeneity = 0.54). However, there was no significant difference in the incidence of solid tumors (including malignant melanoma) (OR: 1.28 [95% CI: 0.85-1.95]) or hematologic SPMs (OR: 1.86; [95% CI: 0.81-4.27]). In conclusion, the use of anti-CD38 mAb-based combination regimens is associated with a higher risk of noninvasive cutaneous SPMs, but not solid tumors or hematologic SPMs. The increased occurrence of noninvasive cutaneous SPMs may be due to enhanced monitoring resulting from longer treatment duration with anti-CD38 mAbs.