Sotrastaurin in Calcineurin Inhibitor–Free Regimen Using Everolimus in De Novo Kidney Transplant Recipients

Authors


Abstract

Sotrastaurin, a novel selective protein-kinase-C inhibitor, inhibits early T cell activation via a calcineurin-independent pathway. Efficacy and safety of sotrastaurin in a calcineurin inhibitor—free regimen were evaluated in this two-stage Phase II study of de novo kidney transplant recipients. Stage 1 randomized 131 patients (2:1) to sotrastaurin 300 mg or cyclosporine A (CsA). Stage 2 randomized 180 patients (1:1:1) to sotrastaurin 300 or 200 mg or CsA. All patients received basiliximab, everolimus (EVR) and prednisone. Primary endpoint was composite efficacy failure rate of treated biopsy-proven acute rejection, graft loss, death or lost to follow-up. Main safety assessment was estimated glomerular filtration rate (eGFR) by MDRD-4 at Month 12. Composite efficacy failure rates at 12 months were higher in sotrastaurin arms (Stage 1: 16.5% and 10.9% for sotrastaurin 300 mg and CsA; Stage 2: 27.2%, 34.5% and 19.4% for sotrastaurin 200 mg, 300 mg and CsA). eGFR was significantly better in sotrastaurin groups versus CsA at most time points, except at 12 months. Gastrointestinal and cardiac adverse events were more frequent with sotrastaurin. Higher treatment discontinuation, deaths and graft losses occurred with sotrastaurin 300 mg. Sotrastaurin combined with EVR showed higher efficacy failure rates and some improvement in renal allograft function compared to a CsA-based therapy.

Abbreviations
CNI

calcineurin inhibitor

CsA

cyclosporine

eGFR

estimated glomerular filtration rate

EVR

everolimus

HLA

human leukocyte antigen

ITT

intent-to-treat

MDRD

modification of diet in renal disease

mTOR

mammalian target of rapamycin

tBPAR

treated biopsy-proven acute rejection

Introduction

Calcineurin inhibitor (CNI)-based immunosuppressive regimens (cyclosporine A [CsA] and tacrolimus) have significantly improved short-term allograft survival [1, 2]. However, long-term use of CNI is associated with chronic allograft nephrotoxicity, neurotoxicity, malignancies and other side effects such as hypertension and hyperlipidemia [1-4]. Thus, there is a need for CNI-free regimens that are safe and provide adequate rejection prophylaxis. Previous attempts of CNI-free regimens using the combination of sirolimus and mycophenolate mofetil resulted in unacceptable rates of rejection and treatment discontinuation [5, 6].

Sotrastaurin is a novel oral immunosuppressant that blocks early T cell activation and IL-2 production by inhibiting classical and novel protein kinase C (PKC) isoforms [7] involved in the activation of B cells and T cells via transcription factor nuclear factor-kappa B [8-10]. Sotrastaurin, administered as a single agent or in combination with a suboptimal dose of CsA, was shown to prolong kidney allograft survival in nonhuman primates [11, 12], and similar results were obtained when sotrastaurin was used in CNI-free regimens, along with very low-dose everolimus (EVR) or fingolimod [13].

In an initial Phase II trial, sotrastaurin (200 mg b.i.d.) demonstrated efficacy comparable to mycophenolic acid (MPA), with less frequent leukopenia in low-risk kidney transplant recipients receiving basiliximab induction, tacrolimus and corticosteroids [14]. Nevertheless, conversion from tacrolimus to MPA after 3 months resulted in an increased incidence of acute rejection. In a CNI-free Phase II trial, a higher dose of sotrastaurin (300 mg b.i.d.) combined with MPA resulted in a significantly higher incidence of acute rejection compared to tacrolimus and MPA [15]. The present Phase IIa/IIb study investigated the efficacy and safety of two dose levels of sotrastaurin (300 or 200 mg b.i.d.) versus CsA in low-risk de novo kidney transplant recipients receiving basiliximab induction, EVR and corticosteroids.

Materials and Methods

Study design

This was a 12-month, randomized, multicenter, open-label, sequential cohort, dose-finding (ClinicalTrials.gov: NCT00504543) two-staged study (Stage 1: Phase IIa, assessment of efficacy; Stage 2: Phase IIb, dose-finding), conducted between September 2007 and April 2011 in 18 countries across Europe, South America, Australia and Asia. In Stage 1, patients were randomized (2:1) to receive sotrastaurin 300 mg b.i.d. or CsA combined with EVR; in Stage 2, patients were randomized (1:1:1) to receive sotrastaurin 300 mg or 200 mg b.i.d. or CsA combined with EVR (Figure 1). The randomization list was generated using a validated automated system under the supervision of Novartis and allocation was done using blinded treatment allocation cards.

Figure 1.

Study design CsA, cyclosporine; EVR, everolimus; STN, sotrastaurin; Tx, transplantation

Patient recruitment

Recruitment of patients was planned in three steps. Stage 1 started with a pilot phase involving patients (n = 45) at selected sites to confirm the absence of major concerns related to the intensity or tolerability of the immunosuppression regimen. After 3 months of treatment and first interim analysis of safety and efficacy data, recruitment for the remainder of Stage 1 was completed following satisfactory findings and recommendations from the Study Scientific Committee (SSC) and Data Monitoring Committee (DMC). Following a second interim analysis, based on all Stage 1 patients (n = 131) after an additional 3 months' treatment, and findings of comparable efficacy for the sotrastaurin 300 mg b.i.d. and CsA control regimens (upper bound of 95% confidence interval [CI] for difference between treatment groups ≤20%), an additional sotrastaurin 200 mg b.i.d. arm was subsequently introduced to help determine optimal sotrastaurin dose for a Phase III program.

Inclusion/exclusion criteria

Identical inclusion/exclusion criteria were followed in Stage 1 and Stage 2: Patients eligible for inclusion were adult (aged ≥18 years) recipients of a primary renal allograft from a deceased, living unrelated or nonHLA identical living related donor (10–65 years) with a cold ischemia time <24 h and with a functional graft (defined as urine output >250 mL/12 h for patients without residual urinary output from the native kidneys or a decrease in serum creatinine by ≥20% from pretransplant level) within 24 h after graft reperfusion.

Exclusion criteria included recipients of multi-organ, complement-dependent cytotoxicity (CDC) crossmatch-positive or ABO-incompatible transplant or with previous organ transplantation, or those who received allograft from a nonheart beating donor were excluded. Sensitized patients (most recent anti-HLA Panel Reactive Antibodies [PRA] >20% by a CDC-based assay or >50% by a flow cytometry or enzyme-linked immunosorbent assay-based assay) or patients identified otherwise to be at high immunological risk were also excluded. Other notable exclusion criteria included patient use of strong inducers or inhibitors of CYP3A4 at screening; patients with a history of heart disease as defined by QTcF >500 ms, long QT-syndrome, left bundle branch block, hospitalization for heart failure or left ventricular dysfunction; symptomatic coronary artery disease; persistent arrhythmias and patients with malignancy. All randomized patients signed an informed consent form, and the study was approved by local Institutional Review Boards and conducted in compliance with Good Clinical Practice. An independent DMC was convened to review emerging data.

Intervention and concomitant medications

All patients received two doses of basiliximab (Simulect®; Novartis Pharma AG, Basel, Switzerland) 20 mg (prior to transplant and Day 4 posttransplant). Patients were maintained on corticosteroids, tapered to prednisone 5–10 mg/day (or equivalent) by the end of Month 1 until Month 12. Based on randomization category, patients received fixed 200 or 300 mg b.i.d. sotrastaurin doses or CsA (starting dose 4–8 mg/kg/day). Additionally, patients received EVR 1.5 mg/day in the CsA arm and 3 mg/day in the sotrastaurin arms. The first dose of EVR, sotrastaurin or CsA was administered within 24 h of graft reperfusion (Day 1), and all study drugs were taken concomitantly twice daily.

CsA doses were adjusted to maintain whole-blood C0 concentrations (C0) between 100 and 200 ng/mL (Month 1), 75–150 ng/mL (Months 2–3), 50–100 ng/mL (Months 4–5) and 25–50 ng/mL (Months 6–12). EVR dosing was adjusted to reach the targeted trough level (C0) of 4–8 ng/mL for sotrastaurin 300 mg and CsA arms, within 5 days after treatment start. To minimize the risk of efficacy failure in Stage 2, patients randomized to sotrastaurin 300 mg b.i.d. showing trough concentrations <800 ng/mL (blinded assessment of the central lab) were instructed to maintain target EVR trough concentrations between 6 and 8 ng/mL; in those randomized to sotrastaurin 200 mg, further EVR dose adjustment was initiated from Day 15 to reach 8–12 ng/mL by Day 22.

In all suspected rejection episodes, a graft core biopsy was performed within 48 h and graded according to Banff 2003 criteria [16]. Patients were discontinued from study treatment and converted to standard of care as per center practice if they required antibody treatment for a rejection episode, experienced a biopsy-proven acute rejection (BPAR) of Banff grade ≥2, a corticosteroid-resistant rejection, or had >1 episode of rejection.

Efficacy assessment

The primary efficacy variable was the incidence of composite efficacy failure, defined as treated BPAR (tBPAR) grade ≥1A, graft loss, death or loss to follow-up. Primary efficacy was evaluated at Month 3 in Stage 1 and at Month 6 in Stage 2. Secondary efficacy endpoints included incidences of individual components of composite efficacy failure, treated acute rejections (AR) and chronic allograft nephropathy (CAN) according to Banff 2003 in all performed biopsies [17]. Any condition that received anti-rejection treatment was considered a treated AR, irrespective of biopsy. CAN was defined as chronic rejection confirmed by a biopsy graded I (mild), II (moderate) or III (severe) using local pathologist's evaluation of all biopsy readings.

Safety assessments

Renal function as measured by estimated glomerular filtration rate (eGFR) using the 4-variable MDRD formula was the primary safety endpoint. Other safety assessments included collection of adverse events (AEs), serious adverse events (SAEs), including infections, vital signs, lab parameters and electrocardiography (ECG) and malignancies. CNI-specific AEs (tremor, gingival hyperplasia, hypertrichosis, muscular and skeletal pain, blood pressure [BP] and selected parameters) were assessed on an exploratory basis.

Statistical analysis

Sample sizes were chosen for the CI to ensure sufficient evidence of noninferiority between event rates in a sotrastaurin arm versus CsA arm with a 20% noninferiority margin for Stage 2. Randomization of 129 patients in Stage 1 and 180 patients in Stage 2 was intended. Kaplan–Meier methodology was used to estimate composite efficacy failure event rates at Month 3 for Stage 1 and at Month 6 for Stage 2 for the intent-to-treat (ITT) population. Greenwood's formula was used to estimate standard errors and to derive the two-sided 95% CI from the Z-test statistic distribution for the difference in event rates between the sotrastaurin and CsA arms. Descriptive statistics were used to evaluate eGFR at Month 3, 6 and 12 for Stage 1 and Stage 2. Between group comparisons were performed using the Wilcoxon Rank Sum test supported by the 95% CI for the location shift between treatment groups.

Results

Baseline demographics

A total of 402 renal transplant patients were screened, and 311 were randomized into the two stages (Figure 2). In Stage 1, 131 patients were randomized (2:1, sotrastaurin 300 mg and CsA), 45 in the pilot phase and 86 after the first interim analysis. All patients in the ITT population were included in the safety analysis. In Stage 2, 180 were randomized 1:1:1 into the three treatment arms (63, 55 and 62 patients in the sotrastaurin 200 mg, 300 mg and CsA arms, respectively). All patients, except one who never received study medication, were included in the safety analysis.

Figure 2.

Flow of patients *Ineligibility may have occurred due to more than one reason. 1Others include administrative problems, protocol violation, death and graft loss. CsA, cyclosporine; STN, sotrastaurin

Demographic and background characteristics were well-balanced across the treatment arms and between the two stages (Table 1). No significant differences between treatment groups were noted. Mean recipient age was 43–46 years, and the majority of patients were Caucasian (Stage 1, 85–87%; Stage 2, 66–76%). Mean donor age was 41–46 years, with a higher proportion of living donors in Stage 1 (67% for sotrastaurin 300 mg; 61% for CsA) than in Stage 2 (51% in each arm). Mean cold ischemia time for deceased-donor allograft was approximately 15 h in all treatment groups.

Table 1. Baseline demographics and characteristics of donors and recipients
Recipient characteristicsStage 1Stage 2
STN 300 mg (N = 85)CsA (N = 46)STN 200 mg (N = 63)STN 300 mg (N = 55)CsA (N = 62)
  1. PRA, panel reactive antibody; CIT, cold ischemic time; CsA, cyclosporine; SD, standard deviation; STN, sotrastaurin; no significant differences between treatment groups were noted.
Mean age, years ± SD45.8 ± 13.943.2 ± 11.0245.5 ± 13.744.3 ± 13.645.0 ± 11.8
Male, n (%)53 (62.4)32 (69.6)39 (61.9)36 (65.5)42 (67.7)
Caucasian, n (%)74 (87.1)39 (84.8)47 (74.6)36 (65.5)47 (75.8)
Major end-stage disease leading to transplantation, n (%)
Glomerulonephritis/glomerular disease19 (22.4)9 (19.6)11 (17.5)9 (16.4)13 (21.0)
Pyelonephritis4 (4.7)2 (4.3)1 (1.6)1 (1.8)1 (1.6)
Polycystic disease16 (18.8)7 (15.2)13 (20.6)9 (16.4)10 (16.1)
Hypertension/nephrosclerosis5 (5.9)6 (13.0)5 (7.9)11 (20.0)10 (16.1)
Diabetes mellitus4 (4.7)3 (6.5)4 (6.4)4 (7.3)6 (9.7)
Others/unknown37 (43.5)19 (41.3)29 (46.0)21 (38.2)22 (35.5)
Preoperation status, n (%)
Hemodialysis54 (63.5)27 (58.7)42 (66.7)39 (70.9)41 (66.1)
Peritoneal dialysis8 (9.4)9 (19.6)8 (12.7)6 (10.9)8 (12.9)
None23 (27.1)10 (21.7)13 (20.6)10 (18.2)13 (21.0)
PRA
>5%, n (%)6 (7.1)2 (4.3)4 (6.3)4 (7.3)4 (6.5)
Range (most recent evaluation)0.0–25.00.0–24.00.0–24.00.0–38.00.0–27.0
Range (peak evaluation)0.0–75.00.0–40.00.0–24.00.0–42.00.0–49.0
CIT, mean hours ± SD14.6 ± 4.214.9 ± 5.616.0 ± 5.016.7 ± 4.215.0 ± 5.3
Donor characteristics
Mean age, years ± SD42.9 ± 12.445.8 ± 12.742.4 ± 14.141.0 ± 12.043.4 ± 12
Living related36 (42.4)21 (45.7)23 (36.5)17 (30.9)24 (38.7)
Living unrelated21 (24.7)7 (15.2)9 (14.3)11 (20.0)7 (11.3)
Deceased heart beating28 (32.9)18 (39.1)31 (49.2)27 (49.1)31 (50.0)

A total of 39% of patients discontinued the study drug before Month 12. Rate of discontinuation was higher with sotrastaurin 300 mg arm (45%) compared with sotrastaurin 200 mg (34.9%) and CsA (33.3%). The most frequent reasons for study drug discontinuation were AEs and unsatisfactory therapeutic effect. Overall, 91%, 97% and 96% of the patients completed the study period, respectively (Figure 2).

Exposure to study drugs

In the sotrastaurin 200 mg arm, median C0 ranged from 655 to 1071 ng/mL during the study period (Figure 3A). The proportion of patients receiving <400 mg/day varied from 0% to 33.3%, and the proportion of patients showing C0 concentrations <300 or >3000 ng/mL varied from 0% to 15.2% and 0% to 2.4%, respectively. Median sotrastaurin C0 for the sotrastaurin 300 mg arm were between 813 and 1312 ng/mL during the study period (Figure 3b). The proportion of patients receiving <600 mg/day varied from 0% to 17.6% in Stage 1 and from 0% to 36.4% in Stage 2, and the proportion of patients showing C0 concentrations <800 or >3000 ng/mL varied from 8.7% to 17.9% and from 0% to 9.6%, respectively.

Figure 3.

Median drug concentration over the 12-month study period. Median sotrastaurin concentration in patients randomized to (A) 200 mg or (B) 300 mg sotrastaurin arms; (C) median CsA concentration (Stage 1 and 2 combined); (D) median EVR concentrations in patients randomized to sotrastaurin 200 or 300 mg (Stage 1 and 2 combined), or CsA (Stage 1 and 2 combined) Dotted lines in panels A–C and the background color in panel D indicates the target trough levels (dark gray represents sotrastaurin 200 mg; light gray represents sotrastaurin 300 mg and CsA). CsA, cyclosporine; STN, sotrastaurin

CsA exposure was reduced as expected from Month 3 onwards, and the target C0 was maintained in 56.3% of the combined patient population at Month 12 (Figure 3C). Median CsA C0 concentrations were 106, 74, 61 and 40 ng/mL for Month 2, 4, 6 and 12, respectively. In the sotrastaurin 300 mg arm at Month 12, median daily doses of EVR were 3 mg, and the median EVR C0 concentration was 5 ng/mL, with 83.3% (Stage 1) and 57.1% (Stage 2) of patients showing EVR C0 within the target range. Similarly, in the sotrastaurin 200 mg arm, median EVR daily dose was 3.5 mg, and median EVR C0 was 7.0 ng/mL, with 61.9% of patients showing EVR concentrations below the target, a tendency observed from Month 1 onward. Finally, in the CsA arm, median daily EVR dose was 1.5 mg, and median EVR C0 was 5 ng/mL, with 70.6% (Stage 1) and 72.1% (Stage 2) of patients showing EVR C0 within the target range.

Efficacy endpoints

In the ITT population in Stage 1, the incidence of composite efficacy failure at Month 3 was comparable between the sotrastaurin 300 mg and CsA arms (p = 0.943; Table 2). At Month 12, the composite efficacy failure rate was higher for sotrastaurin 300 mg (16.5%) than CsA (10.9%; Figure 4A; Table 2). In Stage 2, composite efficacy failure rates were higher in the sotrastaurin arms (200 mg, 20.7% [p = 0.569]; 300 mg, 30.9% [p = 0.073]) compared with CsA (16.1%) at Month 6, and differences were maintained until Month 12 (27.2%, 34.5% and 19.4%, respectively; Figure 4B; Table 2).

Table 2. Composite efficacy failure rates for Stage 1 and Stage 2
Efficacy results, n (%)Stage 1Stage 2
STN 300 mg (N = 85)CsA (N = 46)p-ValueSTN 200 mg (N = 63)STN 300 mg (N = 55)CsA (N = 62)p-Value vs. STN 200 mgp-Value vs. STN 300 mg
  1. AMR, antibody mediated rejection; tBPAR, treated biopsy-proven acute rejection; CsA, cyclosporine; STN, sotrastaurin.
  2. aThe composite primary endpoint of first biopsy-proven acute rejection, graft loss, death or loss to follow up measured at Month 3 for Stage 1 and Month 6 for Stage 2 (Kaplan–Meier estimate).
  3. bKaplan–Meier estimates.
  4. cAMR: Includes suspicious and evident.
  5. dChronic allograft nephropathy: Defined as chronic rejection confirmed by a biopsy graded I (mild), II (moderate) or III (severe) using local pathologists' evaluation of all biopsy readings.
Efficacy failurea7 (8.2)4 (8.7) 13 (20.7)17 (30.9)10 (16.1)  
Difference to CsA [95% CI]−0.5 [−10.5, 9.6] 0.9434.5 [−9.0, 18.1]14.8 [−0.5, 30.0] 0.5690.073
First tBPAR5 (6.0)3 (6.5)0.90012 (19.1)14 (26.0)10 (16.1)0.7260.220
Graft Loss00NA2 (3.2)2 (3.8)00.1590.124
Death2 (2.4)00.29703 (5.6)0NA0.06
Lost to follow-up01 (2.2)0.17902 (3.7)1 (1.6)0.3170.467
Efficacy failure at Month 12b14 (16.5)5 (10.9) 17 (27.2)19 (34.5)12 (19.4)  
Difference to CsA [95% CI]5.6 [−6.4, 17.6] 0.4007.8 [−7.0, 22.6]15.2 [−0.8, 31.1] 0.3550.073
First tBPAR M0-1211 (13.2)3 (6.5)0.27116 (25.6)15 (28.0)12 (19.4)0.4690.290
Living donor, n/N (%)7/57 (12.7)2/28 (7.1)0.4936/32 (18.8)8/28 (29.7)8/31 (25.8)0.4500.766
Deceased donor, n/N (%)4/28 (14.3)1/18 (5.6)0.36110/31 (32.7)7/27 (26.3)4/31 (12.9)0.0760.216
Graft Loss1 (1.2)00.4642 (3.2)3 (5.7)00.1590.057
Death3 (3.5)00.20304 (7.6)0NA0.028
Lost to follow-up1 (1.2)2 (4.3)0.2551 (1.6)4 (7.6)1 (1.6)0.9950.120
Severity of acute rejection episodes
AMRc00NA1 (1.6)3 (5.5)1 (1.6)0.9870.376
Borderline6 (7.1)1 (2.2)0.0713 (4.8)02 (3.2)0.6480.135
Banff IA-III12 (14.1)4 (8.7)0.32016 (25.4)13 (23.6)13 (21.0)0.6690.637
Chronic allograft nephropathyd8 (9.8)2 (4.4)0.3223 (4.9)5 (9.7)5 (8.1)0.4650.730
Frequency of acute rejection episodes per patients
071 (83.5)42 (91.3) 45 (71.4)39 (70.9)46 (74.2)  
111 (12.9)4 (8.7) 15 (23.8)11 (20.0)12 (19.4)  
21 (1.2)0 (0) 3 (4.8)4 (7.3)4 (6.5)  
32 (2.4)0 (0) 01 (1.8)0  
>300 (0)0.7020000.8110.922
Figure 4.

Kaplan–Meier plot of composite efficacy failure (A) Stage 1 and (B) Stage 2 *Difference from CsA (95% CI). CsA, cyclosporine; STN, sotrastaurin

The higher rates of composite efficacy failure in the sotrastaurin arms were driven primarily by tBPAR in both stages (Table 2). There were few episodes of AR in any treatment group after Month 6, and most ARs were Banff grade 1. There were six graft losses (one in Stage 1 and five in Stage 2), two of which occurred with sotrastaurin 200 mg and four with sotrastaurin 300 mg (one in Stage 1 and three in Stage 2; Table 2). Four graft losses were due to rejections, with one antibody-mediated rejection, which started on treatment, and three reported as cellular rejections, including two postdiscontinuation graft losses. The other two graft losses were due to an on-therapy graft rupture and a terminal graft insufficiency, which occurred 6 Months after discontinuation of therapy. A total of nine patients (three in Stage 1; six in Stage 2) were lost to follow-up.

Safety endpoints

Renal function

A significant improvement in renal function was observed in the sotrastaurin arms versus CsA at nearly all time points from week 1 onward. However, the degree of improvement progressively declined over time (Figure 5A). Median eGFR at Month 6 was 60.0, 57.0 and 54.0 mL/min/1.73 m2 for sotrastaurin 200 mg (p = 0.076), 300 mg (p = 0.029) and CsA arms, respectively. At Month 12, median eGFR for the sotrastaurin arms was not statistically significant different compared with CsA (60.0, 58.0 and 55.0 mL/min/1.73 m2 for sotrastaurin 200 mg [p = 0.330], 300 mg [p = 0.073] and CsA, respectively). In the analysis of patients who remained on assigned treatment, similar results were obtained but with a statistically significant difference for the sotrastaurin 300 mg arm (Figure 5B). Median eGFR at Month 12 was 61.5, 60.5 and 55.0 mL/min/1.73 m2 for sotrastaurin 200 mg (p = 0.280), 300 mg (p = 0.006) and CsA arms, respectively. At Month 6, median eGFR was significantly better for both the sotrastaurin arms compared with CsA (61.0, 60.0 and 54.5 mL/min/1.73 m2 for sotrastaurin 200 mg [p = 0.010], 300 mg [p = 0.002] and CsA, respectively). In the safety analysis population, there were no differences comparing median eGFR of patients receiving CsA or sotrastaurin 300 mg in Stage 1 (55.0 vs. 57.0, p = 0.333) and in Stage 2 (54.5 vs. 59.0, p = 0.109), respectively. In the on-treatment population, there was a significant difference comparing median eGFR of patients receiving CsA or sotrastaurin 300 mg in Stage 1 (54.0 vs. 61.0, p = 0.029) but not in Stage 2 (56.0 vs. 59.0, p = 0.076), respectively. The proportion of patients with urinary protein creatinine ratio >80 mg/mmol after 1 month was 24.1%, 29.8% and 21.7% in sotrastaurin 200 mg (p = 0.733), 300 mg (p = 0.190) and CsA arms, respectively.

Figure 5.

Renal allograft function over 12 months: (A) safety population all patients and (B) on-treatment population Error bars represent the standard deviations. *M3–STN 200 mg: p < 0.001 and STN 300 mg: p < 0.001; **M6–STN 200 mg: p = 0.076 and STN 300 mg: p = 0.029; ***M9–STN 200 mg: p = 0.022 and STN 300 mg: p < 0.001; §M3–STN 200 mg: p < 0.001 and STN 300 mg: p < 0.001; §§M6–STN 200 mg: p = 0.010 and STN 300 mg: p = 0.002; §§§M9–STN 200 mg: P = 0.011 and STN 300 mg: p < 0.001; CsA, cyclosporine; eGFR, estimated glomerular filtration rate; STN, sotrastaurin.

Adverse events

The incidence of AEs was similar across the treatment groups with almost all patients experiencing at least one AE, the majority of which were mild-to-moderate in severity. The most commonly reported AEs are listed in Table 3. The overall incidence of SAEs was similar in all groups, ranging from 61% to 68%. During the study, there were seven deaths, all of which occurred among patients in the sotrastaurin 300 mg arm. In Stage 1, three patients died due to pulmonary embolism, bronchopulmonary aspergillosis and acute myocardial infarction. In Stage 2, the causes of the four reported deaths were cerebrovascular accident, septic shock, sudden death and pulmonary embolism. Among these seven deaths, four occurred during treatment with sotrastaurin plus EVR. None of the deaths was described as related to study medication by the investigators. A higher proportion of patients discontinued study medication due to an AE prior to Month 12 in the sotrastaurin 300 mg arm compared to 200 mg or CsA arms.

Table 3. Incidence of AEs occurring in ≥20% with any arm and AEs of interest
 STN 200 mgSTN 300 mgCsARR (95% CI)
STN 200 mg vs. CsASTN 300 mg vs. CsA
  1. AE, adverse event; CMV, cytomegalovirus; CsA, cyclosporine; NE, not evaluable; SAE, serious adverse event; STN, sotrastaurin.
Total number of patients with AEs63 (100.0)140 (100.0)106 (99.1)1.01 (0.99, 1.03)1.01 (0.99, 1.03)
Total number of patients with SAEs41 (65.1)95 (67.9)66 (61.7)1.06 (0.83, 1.33)1.10 (0.91, 1.33)
Total number of patient died0 (0.0)7 (5.0)0 (0.0)NENE
Number of patient died on treatment0 (0.0)6 (4.3)0 (0.0)NENE
Discontinued study medication prior to Month 12 due to AEs17 (27.0)51 (36.4)28 (26.2)1.03 (0.62, 1.73)1.39 (0.95, 2.05)
AEs (≥20% in any arm)
Edema peripheral24 (38.1)44 (31.4)42 (39.3)0.97 (0.65, 1.44)0.80 (0.57, 1.12)
Pyrexia17 (27.0)20 (14.3)15 (14.0)1.92 (1.03, 3.58)1.02 (0.55, 1.89)
Hypokalemia7 (11.1)32 (22.9)12 (11.2)0.99 (0.41, 2.39)2.04 (1.10, 3.77)
Hypophosphatemia14 (22.2)25 (17.9)19 (17.8)1.25 (0.68, 2.32)1.01 (0.59, 1.73)
Dyslipidemia13 (20.6)15 (10.7)21 (19.6)1.05 (0.57, 1.95)0.55 (0.30, 1.01)
Headache9 (14.3)17 (12.1)23 (21.5)0.66 (0.33, 1.34)0.56 (0.32, 1.00)
Acne14 (22.2)21 (15.0)22 (20.6)1.08 (0.60, 1.96)0.73 (0.42, 1.25)
Hypertension16 (25.4)25 (17.9)27 (25.2)1.01 (0.59, 1.72)0.71 (0.44, 1.15)
AEs of interest
Any gastrointestinal events51 (81.0)116 (82.9)79 (73.8)1.10 (0.93, 1.29)1.12 (0.98, 1.29)
Constipation33 (52.4)71 (50.7)44 (41.1)1.27 (0.92, 1.77)1.23 (0.93, 1.63)
Diarrhea18 (28.6)57 (40.7)22 (20.6)1.39 (0.81, 2.38)1.98 (1.30, 3.02)
Vomiting13 (20.6)49 (35.0)17 (15.9)1.30 (0.68, 2.49)2.20 (1.35, 3.60)
Nausea19 (30.2)46 (32.9)28 (26.2)1.15 (0.70, 1.89)1.26 (0.84, 1.87)
Hematological AEs
Anemia11 (17.5)45 (32.1)34 (31.8)0.55 (0.30, 1.01)1.01 (0.70, 1.46)
Leukopenia3 (4.8)4 (2.9)3 (2.8)1.70 (0.35, 8.16)1.02 (0.23, 4.46)
Thrombocytopenia4 (6.3)3 (2.1)3 (2.8)2.26 (0.52, 9.79)0.76 (0.16, 3.71)
Any infections51 (81.0)106 (75.7)76 (71.0)1.14 (0.96, 1.35)1.07 (0.91, 1.24)
Bacterial19 (30.2)59 (42.1)39 (36.4)0.83 (0.53, 1.30)1.16 (0.84, 1.59)
Fungal8 (12.7)17 (12.1)9 (8.4)1.51 (0.61, 3.71)1.44 (0.67, 3.11)
Viral14 (22.2)26 (18.6)18 (16.8)1.32 (0.71, 2.47)1.10 (0.64, 1.91)
BK virus5 (7.9)4 (2.9)1 (0.9)8.49 (1.01, 71.06)3.06 (0.35, 26.96)
CMV04 (2.9)2 (1.9)NE1.53 (0.29, 8.19)
Urinary tract infection21 (33.3)47 (33.6)33 (30.8)1.08 (0.69, 1.69)1.09 (0.75, 1.57)
Other20 (31.7)45 (32.1)31 (29.0)1.10 (0.69, 1.75)1.11 (0.76, 1.63)
Unknown15 (23.8)39 (27.9)27 (25.2)0.94 (0.54, 1.63)1.10 (0.72, 1.68)
CNI-specific AEs
Tremor2 (3.2)5 (3.6)15 (14.0)0.23 (0.05, 0.96)0.25 (0.10, 0.68)
Muscular/skeletal pain0 (0.0)6 (4.3)6 (5.6)NE0.76 (0.25, 2.30)
Hypertrichosis1 (1.6)10 (7.1)17 (15.9)0.10 (0.01, 0.73)0.45 (0.21, 0.94)
Gingival hyperplasia1 (1.6)3 (2.1)5 (4.7)0.34 (0.04, 2.84)0.46 (0.11, 1.88)
mTOR inhibitor associated AEs, (%)
Proteinuria reported as AE9 (14.3)12 (8.6)15 (14.0)1.02 (0.47, 2.19)0.61 (0.30, 1.25)
Protein/creatinine ratio >22.7 mg/mmoL, n/N53/62 (85.5)117/132 (88.6)83/106 (78.3)1.09 (0.95, 1.26)1.13 (1.01, 1.27)
Hyperlipidemia reported as AE5 (7.9)12 (8.6)11 (10.3)0.77 (0.28, 2.12)0.83 (0.38, 1.82)
Total cholesterol ≥9.1 mmol/L6 (9.5)9 (6.4)21 (19.6)0.49 (0.21, 1.14)0.33 (0.16, 0.69)
Wound complications5 (7.9)4 (2.9)5 (4.7)1.70 (0.51, 5.64)0.61 (0.17, 2.22)
Lymphocele11 (12.5)17 (12.1)17 (15.9)1.10 (0.55, 2.19)0.76 (0.41, 1.43)
Hepatic enzymes increased7 (11.1)5 (3.6)0 (0.0)NENE
Gastrointestinal events

Gastrointestinal AEs were reported more frequently with sotrastaurin than CsA. More than 80% of patients in both sotrastaurin arms experienced gastrointestinal AEs versus 74% in CsA arm (Table 3). Compared with patients receiving CsA, those receiving sotrastaurin 300 mg had a higher incidence of diarrhea and vomiting, with severe diarrhea reported in two patients in the 300 mg arm. Most events were reported during the first month posttransplantation. Seven patients required study drug dose adjustment or temporary interruption due to diarrhea (two in the sotrastaurin 200 mg arm, four in the sotrastaurin 300 mg arm and one in the CsA arm), but none required permanent discontinuation.

Vomiting was reported as an SAE in one patient and three patients in the sotrastaurin 200 and 300 mg arms, respectively, with severe vomiting reported for one patient in each sotrastaurin arm. In the sotrastaurin 300 mg arm, two patients had discontinued study drug and three patients had dose reduction or interruption due to vomiting. Most events occurred during first month of study drug initiation.

Hematological AEs

A lower incidence of anemia and a higher incidence of leukopenia were reported with sotrastaurin 200 mg compared with sotrastaurin 300 mg and CsA. Hemoglobin levels <4.39 mmol/L, platelet count ≤75 × 109/L and incidences of thrombocytopenia were more frequent in the sotrastaurin arms versus CsA.

Infection

Overall, incidences of infection were higher in the sotrastaurin arms compared with CsA (Table 3). However, 37.1% of patients on sotrastaurin 300 mg experienced serious infections versus 23.8% receiving sotrastaurin 200 mg and 26.2% receiving CsA. Urinary tract infection was the most commonly reported serious infection in all treatment groups (6.3%, 7.9% and 7.5% for the sotrastaurin 200 mg, 300 mg and CsA arms, respectively). BK-polyoma viremia was reported in 11.1%, 7.9% and 5.6% of patients in sotrastaurin 200, 300 and CsA arms, respectively. Only 10 patients experienced BK-polyoma infections, which were reported as an AE. Based on virology results, BK nephropathy events were restricted to sotrastaurin arms only, three (4.8%) in the sotrastaurin 200 mg arm and one (0.7%) in the sotrastaurin 300 mg arm.

Heart rate

In the on-treatment population, a higher median heart rate (central ECG) was noted in both sotrastaurin arms versus CsA (a difference of up to 9.5 and 11 bpm in the sotrastaurin 200 and 300 mg arms, respectively) up to Month 3, with the difference attenuating to approximately 5–8 bpm by Month 12. Cardiac arrhythmias were reported more frequently with sotrastaurin than with CsA (25.4% for the sotrastaurin 200 mg arm [risk ratio 1.81; 95% CI 0.96, 3.41], 25.7% for the sotrastaurin 300 mg arm [risk ratio 1.83; 95% CI 1.06, 3.17] versus 14.0% for the CsA arm). Patients in the sotrastaurin arms experienced a consistently lower systolic and diastolic BP (sitting measurement) than patients receiving CsA.

Discussion

Interpretation of Stage 1 and Stage 2 results of this Phase II study indicates that sotrastaurin combined with EVR showed a higher incidence of efficacy failure at 12 months compared to a combination regimen of CsA and EVR, due primarily to higher incidence of biopsy-confirmed acute rejection in the sotrastaurin arms. Furthermore, all deaths and graft losses occurred in patients treated with sotrastaurin. As observed in other CNI-free regimens, patients receiving sotrastaurin and EVR showed sustained improvement in renal allograft function, primarily in the on-treatment population, and reduction in other CNI-related toxicities. There was no obvious relationship between sotrastaurin dose or concentration and efficacy failure at Month 12. The sotrastaurin 200 mg arm combined with higher EVR exposure was slightly more efficacious than the sotrastaurin 300 mg arm with lower EVR exposure. No new emerging AEs were observed compared to previous sotrastaurin trials, but patients receiving sotrastaurin experienced more gastrointestinal and cardiac-related AEs, leading to a higher treatment discontinuation rate.

Comparison of Stage 1 and Stage 2 results shows clear differences in efficacy. The incidence of the composite efficacy endpoint in the control arm (CsA + EVR) was two times higher in Stage 1 than in Stage 2 (10.9% vs. 19.4%, respectively, Table 2). Differences were also observed in sotrastaurin arms (Table 2), precluding a planned combined efficacy analysis. Reasons for these findings are not clear, but eventually could be due to a tighter selection of low risk recipients in Stage 1. No differences in the type (ACR or AMR) or severity of AR episodes were apparent in comparing stages or treatment groups. Of the six graft losses, four were due to rejection. Treatment group, stage, creatinine value at Month 1, donor–recipient gender match, PRAs, donor age and donor source were not associated with efficacy failures in an exploratory multifactorial analysis.

Per study protocol, pooled Stage 1 and Stage 2 data were used for all safety assessments. Patients in the sotrastaurin arms showed superior renal function from week 1 to Month 5, but no significant difference was observed compared to the control group at Month 12. In the on-treatment population, superior renal function up to Month 12 was observed for patients receiving sotrastaurin 300 mg compared with the control group but not for patients receiving sotrastaurin 200 mg, perhaps due to the small sample size. The higher incidence of AR episodes and treatment discontinuations in the sotrastaurin arms, with conversion to a CNI-based immunosuppressive regimen, may have contributed to these findings. No significant differences were observed in median urinary protein-to-creatinine ratios at 12 months (22.9 vs. 21.7 vs. 18.8 mg/mmol, respectively) or in the incidence of proteinuria reported as AEs.

Although the overall incidence of AEs and SAEs was comparable among all groups, a higher proportion of patients in the sotrastaurin 300 mg arm discontinued study drug due to AEs prior to Month 12. In Stage 2, a particularly higher rate of discontinuation from study medication was observed in patients receiving sotrastaurin 300 mg (50.9%, vs. 35% with sotrastaurin 200 mg and 34% with CsA; Figure 2). Gastrointestinal AEs were more frequent in patients receiving sotrastaurin, with those receiving 300 mg showing a higher incidence of diarrhea and vomiting. Compared to patients receiving CsA, median ventricular heart rate was higher in both the sotrastaurin 200 and 300 mg arms at all timepoints, despite no significant difference in the use of beta-blockers. Central ECG analysis also revealed a higher incidence of cardiac arrhythmias in both sotrastaurin arms, but no significant QT-prolongation was observed in any treatment group. A tendency towards lower BP was observed among patients receiving sotrastaurin. Patients receiving sotrastaurin experienced a higher incidence of infections. Comparing patients receiving sotrastaurin to those receiving CsA, the incidence of CNI-related AEs was lower, but the incidence of mTORi-related AEs was similar.

All deaths occurred in the sotrastaurin 300 mg arm, with four occurring on therapy and three within 30 days after study drug discontinuation. Whether this pattern indicates a true safety concern is not known. The timing and causes of death were not unusual to the transplant recipients. Overall, dose-dependent reduction in tolerability was observed in this study, with sotrastaurin 300 mg dosing being associated with a higher number of AEs, infections, discontinuation due to AEs and deaths.

Interpretation of the results of this preliminary efficacy and dose finding study should be done with caution because of several inherent limitations. The small sample size, open-label design and selected inclusion criteria, although typical for a Phase II study, preclude any extrapolation. Furthermore, the reasons for the observed differences in Stage 1 and Stage 2, even in the control group, remain unclear. Due to the limited benefit over current standard-of-care, further development of sotrastaurin for the prevention of AR in kidney transplant recipients was halted. However, other potent and selective PKC inhibitors with improved tolerability may be a treatment option in the future.

In conclusion, this Phase II trial demonstrates that in low-risk kidney transplant recipients receiving basiliximab induction, EVR and corticosteroids, the use of sotrastaurin, 200 or 300 mg twice daily was associated with higher efficacy failure compared to CsA. Combination of sotrastaurin with EVR demonstrated benefits in renal function, BP and other CNI-related AEs without increasing the incidence of mTORi-related AEs. Tolerability appears to be dose related and a limiting factor in sotrastaurin use, having led to higher gastrointestinal AEs, infections, increased heart rate and arrhythmias, and ultimately resulting in higher treatment discontinuation compared to CsA.

Acknowledgments

The study was funded by Novartis Pharma AG, Basel Switzerland. We thank Heike Schwende, PhD, Novartis Pharma AG Switzerland, for organizing the development of the manuscript. Editorial assistance was provided by Aparajita Mandal, PhD, and Seema Dimri, Novartis Healthcare Pvt. Ltd., India and BioScience Communications, New York, NY, USA.

Disclosure

H.T. has received research grants from Novartis, Pfizer, Roche, Veloxis and BMS, and consultancy and travel honoraria from Novartis and Pfizer. S.V. has received honoraria from Novartis, Astellas and Wyeth. G.R. has received honoraria from Pfizer, Novartis, Janssen Cilag, BMS and Astellas. K.B. has received research funds and/or honoraria from AiCuris, Pfizer, Novartis, Astellas, Roche, Hexal, Bristol-Myers Squibb, Veloxis Pharma, Effimune Pharma and Siemens. J.M.C. has received honoraria for lectures and advisory Boards from Novartis, Pfizer and Astellas. J.E. is on the Australian Transplant Advisory Boards of Novartis, Pfizer, Roche and Jansen Cilag and her renal unit has received research funding for investigator initiated clinical trials from Novartis and Pfizer. I.K., U.G., and J.K. are employees of Novartis and J.K. owns stocks of Novartis Pharma AG, Basel, Switzerland. Other authors have no conflicts to disclose as described by the American Journal of Transplantation.

Appendix

The A2206 Study Investigators

Argentina: L. Toselli, Buenos Aires; P. Novoa, Cordoba; Austria: J. Pratschke, Innsbruck; F. Muehlbacher, Vienna. Australia: G. Russ, Woodville; J. Eris, Camperdown; J. Kannelis, Clayton. Belgium: P. Peeters, Gent; Brazil: H. Tedesco, São Paulo; V. Garcia, Porto Alegre. Colombia: J. Schweineberg, Cali; F. Giron, Bógota. Czech Republic: S. Vitko, Prague. France: L. Rostaing, Toulouse; J. Dantal, Nantes; Y. Le Meur, Brest; M. Hazzan, Lille. Germany: K. Budde, Berlin; M. Zeier, Heidelberg. Italy: G. Colussi, Milano; P. Messa, Milano; S. Stefoni, Bologna. Netherlands: W. Weimar, Rotterdam. Norway: B. Lien, Oslo. Poland: M. Klinger, Wroclaw. Spain: J. Grinyo, Bellvitge; R. Marcen, Madrid. Singapore: V. Anantharaman, Singapore. Slovakia: L. Bena, Kosice; E. Lackova, Banska Bystrica. Switzerland: M. Schiesser. Taiwan: P-H. Lee, Taipei, Taiwan.

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