Update from the KarMMA study of CAR T-cell product, bb2121 (ide-cel)

On 6^th December 2019, it was announced that the phase II KarMMA study met its primary endpoint of overall response rate (ORR) and key secondary endpoint of complete response (CR) rate. The KarMMA study is investigating idecabtagene vicleucel (ide-cel, also known as bb2121), in patients with relapsed/refractory multiple myeloma (RRMM). Ide-cel is a chimeric antigen receptor (CAR) T-cell therapy targeting B-cell maturation antigen (BCMA).¹

The KarMMA study was initiated based on positive results from a phase I, CRB-401² study of bb2121 in patients with RRMM, summarized by the Multiple Myeloma (MM) Hub here.

KarMMA (NCT03361748)¹

• Open-label, single arm, multicenter phase II study in patients with RRMM
  • Enrolled; n= 140
  • Treated; n= 128
• Patients were treated at target dose between 150 and 450 x 10⁶ CAR T cells
• Patient characteristics:
  • Patients had received three or more prior lines of therapy including an immunomodulatory drug (IMiD), a proteasome inhibitor (PI) and an anti-CD38 antibody
    • All were refractory to last regimen
    • Refractory to anti-CD38: 94%
    • Triple refractory: 84%
• Key efficacy results are shown in Table 1
• The safety results were consistent with the CRB-401 study in 128 evaluable patients
  • ≥ Grade III cytokine release syndrome (CRS): 5.5%. One CRS event was fatal
  • ≥ Grade III neurotoxicity events: 3.1%. No grade IV events were reported
  • Grade III or higher CRS or neurotoxicity at each target dose was <6%

Table 1. Efficacy results from KarMMA

CAR, chimeric antigen receptor; CR, complete response; ORR, overall response rate; PFS, progression free survival
CAR T-cell dose	150 x 106	300 x 106	450 x 106	150 – 450 x 106
N	4	70	54	128
ORR	50%	68.6%	81.5%	73.4%
CR/stringent CR	25%	28.6%	35.2%	31.3%
Median duration of response	-	9.9 months	11.3 months	10.6 months
Median PFS	-	5.8 months	11.3 months	8.6 months

More detailed data from this trial are due to be presented at an upcoming medical congress. Meanwhile, several abstracts in the field of CAR T-cell therapy are due to be presented at the 61^st American Society of Hematology (ASH) meeting in December 2019.