Figure 6.

The combination of Cy and anti-BCMA/CD3 is curative and induces long-lasting protection from tumor rechallenge. A, WT mice bearing Vk12598 tumors were treated as indicated with control or anti-BCMA/CD3 with or without Cy for 2 weeks. B, Relative M-spike levels (% of day 0) ­measured 7 days after the indicated treatment. Each dot represents an M-spike from an individual mouse. Bars show mean M-spike levels with SD.C, M-spike levels (G/A) measured weekly. Each line indicates one mouse. D, Kaplan–Meier survival plot in days from the initiation of treatment of Vk12598 tumor–bearing mice receiving treatments in A. P values derived from the Mantel–Cox log-ranked X² test. Arrow indicates the time at which anti-BCMA/CD3–treated mice were retransplanted with 1 million Vk12598 myeloma cells. At the same time, previously untreated and not transplanted age-matched littermate WT mice were also transplanted with the same pool of Vk12598 cells. E, Number of CD138⁺ tumor cells, CD3⁺ T cells, and regulatory CD4⁺ T cells per SPL measured by FCM of samples from necropsied mice 3 days after treatment initiation of groups in A. F, Ratio of CD8⁺ T cells to CD138⁺ tumor cells per mouse. G, Representative example of FCM measurement of circulating memory T cells collected from mice in F on day 90, prior to rechallenge with Vk12598. H, Quantification of effector memory CD4⁺ and CD8⁺ T cells per μL of blood on day 90, prior to challenge. I, Frequency of IFNγ-producing effector memory CD4⁺ and CD8⁺ T cells in the blood of mice prior to challenge with Vk12598 in F. J, M-spike (G/A) after rechallenge of cured or matched WT control mice with Vk12598 cells. P values derived from unpaired t tests. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001. ns, not significant.