Serum creatinine levels in relation to CAR T-cell infusion. The horizontal axis represents time (weeks) in relation to CAR T-cell infusion, and the vertical axis represents serum creatinine value. Baseline serum creatinine in cases 1, 2, and 3 were 1.20, 0.74, and 1.53 mg/dL, respectively, at time of CAR T-cell infusion. Case 1 developed AKI at week 21 that was attributed to possible acute graft rejection (Banff classification; i1,t1 v0, g0, ptc 0, c4d0, cg0, mm0, ah2, cv1, ci 0, and ct0). His dd-cfDNA level increased from 0.55% to 4.6% at week 16 with no detectable DSA. Repeat DSA at week 28 was positive. Case 3 kidney function remained stable throughout the therapy, and case 2 developed AKI at week 7 that was attributed to hypovolemia and resolved with fluid resuscitation. ah, arteriolar hyalinosis; AKI, acute kidney injury; ci, interstitial fibrosis; ct, tubular atrophy; cv, vascular fibrous intima thickening; DSA, donor-specific antibodies; i, interstitial inflammation; g, glomerulitis; mm, mesangial matrix expansion; ptc, peritubular capillaritis; t, tubulitis; v, arteritis.