Table 2.

Sirolimus pharmacodynamic studies in adult alloHCT recipients receiving sirolimus as postgraft immunosuppression ^a

Study	Study population	Immunosuppressant	Sirolimus PK methods	Pharmacodynamic results
Rodriguez et al., 201087	N=85 Ages 10–67 yr Regimens MA: N=85, FLU/Mel, TBI/etoposide, BU/CY Donors Related: N=85 Graft sources Marrow: N=5 PBSC: N=80	Sirolimus loading dose 12mg Sirolimus daily dose 4mg/day Sirolimus starting day Day −3 Other IS Tacrolimus 0.02mg/kg/day continuous infusion on day −3, targeted to 5–10ng/mL	Time points Trough concentrations Frequency At least weekly until day +100 Target concentration 3–12 ng/mL Assay HPLC of serum	Data analysis Multivariate analysis including median sirolimus C0 through day +14 after transplant Pharmacokinetics Median sirolimus concentration for the first 30 days was 7.2 ng/mL (IQR, 5.9, 8.9) Significant differences in sirolimus concentrations according to the 3 conditioning regimens Acute GVHD Not evaluated Sinusoidal obstruction syndrome Not evaluated Thrombotic microangiopathy Over the first 30 days, median sirolimus level at onset of TMA was 8.1 ng/mL (range, 5.3–13.3); this was not significantly different from the median level for non-TMA patients, which was 7.2 ng/mL (range, 2.5–18.8, p=0.33) Examined the effect of sirolimus level on TMA risk using cut points at each quartile. None of the cut-points were significantly associated with TMA risk. NRM Not evaluated Drug-drug interactions Not evaluated
Pidala et al., 2012211	N=37 Ages 25–68 Regimens MA: N=37, FLU/targeted BU; pentostatin/BU, FLU/Mel Donors Related: N=17 URD: N=20 Graft sources PBSC: N=37	Sirolimus loading dose 9 mg Sirolimus daily dose Not provided Sirolimus starting day Day −1 Other IS Tacrolimus 0.02mg/kg/day continuous infusion starting on day −3, targeted to 3–7 ng/mL	Time points Not provided Frequency Not provided Target concentration 5–14 ng/mL Assay Not provided	Data analysis Time-dependent Cox modeling with sirolimus concentration Pharmacokinetics Not evaluated Acute GVHD Using time-dependent Cox modeling, could not detect significant relationships between sirolimus concentration and grades II-IV or grades III-IV acute GVHD Sinusoidal obstruction syndrome Not evaluated Thrombotic microangiopathy Not evaluated NRM Not evaluated Drug-drug interactions Not evaluated
Johnston et al., 2012115	N=11 Ages 26–59 Regimens MA: N=11, varied Donors Related: N=11 Graft sources PBSC: N=11	Sirolimus loading dose 12 mg Sirolimus daily dose 4 mg Sirolimus starting day Day −3 Other IS MMF: 15mg/kg twice daily IV, starting day 0 at least 2 h after end of donor cell infusion	Time points Not provided Frequency Not provided Target concentration 3–12 ng/mL, serum trough concentration Assay Not provided	Acute GVHD No correlation between maximum or median sirolimus trough concentrations and the diagnosis of acute GVHD Sinusoidal obstruction syndrome Not evaluated Thrombotic microangiopathy Not evaluated Non-relapse mortality Not evaluated Drug-drug interactions Not evaluated Other No correlation between maximum or median sirolimus trough concentrations and toxicities requiring sirolimus discontinuation
Kiel et al., 2012117	N=59 Ages 23–59 yr Regimens MA: N=59, TBI/CY, TBI/etoposide,, BU/fludarabine, BU/clofarabine, CY/thiotepa Donors Related: N=25 URD: N=34 Graft sources Marrow: N=12 PBSC: N=47	Sirolimus loading dose 12mg Sirolimus daily dose 4mg/day Sirolimus starting day Day −3 Other IS Tacrolimus: 0.02mg/kg/day continuous infusion, targeted to whole blood C0 of 5–10ng/mLc using microparticle enzyme immunoassay	Time points Trough concentrations, obtained 30–60 min before morning dose Frequency At least 3 times/week, between days 0–35 Target concentration 5–15 ng/mL Assay Microparticle enzyme immunoassay of whole blood	Data analysis 2-sided Fisher’s exact test analysis comparing mean and mean summative sirolimus C0 in patients with sinusoidal obstruction syndrome (N=12) and those without (N=47) Pharmacokinetics Not evaluated Acute GVHD Not evaluated Sinusoidal obstruction syndrome (SOS) Mean sirolimus C0significantly higher in patients with SOS versus those without (mean ± SD: 10.5 ± 1.7 ng/mL vs. 8.7 ± 1.8 ng/mL; p=0.003) Mean summative sirolimus C0 significantly higher in patients with SOS versus those without (mean ± SD: 19.7 ± 3.3 ng/mL vs. 17.1 ± 2.3 ng/mL; p=0.003) Thrombotic microangiopathy Not evaluated NRM Not evaluated Drug-drug interactions Not evaluated
Goyal et al., 2013104	N=40 Ages 4–22 yr Regimens MA: N=40 CY/TBI/thiotepa Donors Related: N=16 URD: N=24 Graft sources Marrow: N=18 PBSC: N=1 UCB:N=23 Two patients received both marrow and UCB	Sirolimus loading dose None Sirolimus dose 2.5mg/m2/day Sirolimus starting day Day 0: N=38 Day +1: N=1 Day +2: N=1 Other IS Tacrolimus: 0.03mg/kg/day continuous infusion starting on day +2, targeted to 5–10 ng/mL Methotrexate:5 mg/m2 IV for four or five doses	Time points Trough: Trough concentrations AUC: 0, 0.5, 1, 2, 4, 6, 12, and 24h after oral dose after patient was at steady-state (had received minimum of 4 doses) Frequency Trough: Determined by clinical care AUC: Once; blood samples obtained after patient had received median of 6 doses (range: 4–10) Target concentration 3–12 ng/mL Assay HPLC/MS of whole blood	Data analysis Created population pharmacokinetic (popPK) model Covariates: Age. The average Cl/F of sirolimus was 3-fold greater and Vd/F was 2-fold greater in patients ≤12 years old than in those >12 years. Not covariates: sex, body weight, hemoglobin, bilirubin, aspartate aminotransferase, alanine aminotransferase, albumin, blood urea nitrogen, and serum creatinine) Pharmacokinetics Non-compartmental analysis in 33 patients C0 before dose (mean ± SD) was 8.0 ± 4.6 ng/mL AUC0–24h (mean ± SD) was 401.1 ± 316.3 ng×h/mL Acute GVHD Sirolimus C0 concentration(mean ± SD) were significantly lower in patients (N=10) who developed grades III-IV acute GVHD compared to those (N=22) who developed grades 0-II acute GVHD (6.1±2.9 ng/ mL vs. 9.4±5.5 ng/mL; p=0.044) Sinusoidal obstruction syndromeb Not evaluated Thrombotic microangiopathy Not evaluated NRM Not evaluated Drug-drug interactions Dose-normalized sirolimus trough concentrations significantly higher in patients (N=15) receiving concomitant fluconazole (p=0.018)
Shayani et al., 2013116	N=177 Ages 10–70 yr Regimens MA:N=71, TBI/CY, TBI/etoposide, BU/CY RIC: N=106, FLU/Mel Donors Related: N=82 URD: N=95 Graft sources Marrow: N=23 PBSC: N=154	Sirolimus loading dose 12mg Sirolimus daily dose 4mg/day Sirolimus starting day Day −3 Other IS Tacrolimus: 0.02mg/kg/day continuous infusion starting on day −3, targeted to 5–10 ng/mL Methotrexate: 5 mg/m2 IV on days +1, +3, and +6 if unrelated donord	Time points Trough concentrations Frequency At least weekly Target concentration 3–12 ng/mL Assay Not provided	Data analysis Multivariate analysis including median sirolimus C0 through day +14 after transplant Pharmacokinetics Not evaluated Acute GVHD Not evaluated Sinusoidal obstruction syndrome Not evaluated Thrombotic microangiopathy Highest quartile of median serum sirolimus C0 through day +14 (≥9.9 ng/mL) was associated with an increased risk of TMA (HR=2.19, 95% CI: 1.13–4.27, p=0.02) Based on these results, investigators changed therapeutic sirolimus C0range from 3–12 ng/mL to 5–10 ng/mL NRM Highest quartile of median serum sirolimus C0 through day +14 (≥9.9 ng/mL) was not associated with an increased risk of non-relapse mortality (HR=1.67, 95% CI: 0.79–3.51, p=0.18) Drug-drug interactions Not evaluated

^aExcludes studies in alloHCT recipients where sirolimus was used as treatment of GVHD^212–214; or where sirolimus doses were personalized to a trough concentration of 3–12 ng/mL without a pharmacodynamic analysis^{83–85,90,94,95,97,99,114,215,216}, 5–10 ng/mL^86,88,89, 5–12 ng/mL²¹⁷, 5–15 ng/mL²¹⁸, 6–14 ng/mL⁹⁸, 10–15 ng/mL²¹⁹; or where a short course of sirolimus was given without dose personalization²²⁰.

^bAuthors did not conduct these pharmacodynamic analyses because they determined that they had insufficient sirolimus pharmacokinetic data.

^cTacrolimus start day and methods for calculating summative sirolimus concentrations were not included in the manuscript.

^dOne patient also received ATG.

Abbreviations: alloHCT: allogeneic hematopoietic cell transplantation; BU: busulfan; C₀: trough plasma concentration; CI: confidence interval; Cl/F: apparent oral clearance; CY: cyclophosphamide; FLU: fludarabine monophosphate; GVHD: graft-versus-host disease; HPLC: high-performance liquid chromatography; HR: hazard ratio; IQR: inter-quartile range; IS: immunosuppression; IV: intravenous(ly); MA: myeloablative; Mel: melphalan; MS: mass spectrometry; PBSC: peripheral blood stem cell; RIC: Reduced-intensity conditioning; TBI: total body irradiation; TMA: Thrombotic microangiopathy; UCB: umbilical cord blood; URD: unrelated donor; V_d/F: volume of distribution