Using a threshold of 50 iu/ml to identify participants with suboptimal levels, the proportion of myeloma patients with <50 iu/ml of anti‐S was non‐significantly higher in those on chemotherapy (anti‐CD38/anti‐BCMA, three; other chemo, five) versus those not on chemotherapy [eight (9.6%) versus one (2.2%), p = 0.16]. This evidence concerns the gene TNFRSF17 and plasma cell myeloma.