Clinical Pharmacology for Enjaymo
Mechanism Of Action
Sutimlimab-jome is an immunoglobulin G (IgG), subclass 4 (IgG4) monoclonal antibody (mAb) that inhibits the classical complement pathway (CP) and specifically binds to complement protein component 1, s subcomponent (C1s), a serine protease which cleaves C4. SutimlimabÂjome does not inhibit the lectin and alternative pathways. Inhibition of the classical complement pathway at the level of C1s prevents deposition of complement opsonins on the surface of RBCs, resulting in inhibition of hemolysis in patients with CAD.
Pharmacodynamics
Greater than 90% inhibition of CP was observed following a single sutimlimab-jome infusion and sustained in patients with CAD when sutimlimab-jome concentrations were greater than or equal to 100 mcg/mL. C4 levels returned to normal levels (0.2 g/L) in patients with CAD within one week following the first dose of sutimlimab-jome. Complete CP inhibition following initiation of sutimlimab-jome treatment led to inhibition of hemolysis as evidenced by normalization of bilirubin, decrease in LDH, increase in haptoglobin, and decrease in reticulocytes.
After the first treatment with sutimlimab-jome, near normalization of bilirubin associated with a greater than 1 g/dL increase in hemoglobin was observed, demonstrating the effect of CP inhibition. The extent and duration of the pharmacodynamic response in patients with CAD were exposure dependent for sutimlimab-jome.
Pharmacokinetics
Following administration of the approved weight-based recommended dosages, the exposure of sutimlimab-jome increases proportionally over a dosage range of 60 mg/kg to 100 mg/kg by intravenous infusion (0.3 to 1.5 times the maximum approved recommended dosage based on 75 kg body weight). Steady state was achieved by Week 7 after starting sutimlimab-jome treatment, with an accumulation ratio of less than 2.
Distribution
Sutimlimab-jome binds to C1s in the serum. The volume of distribution at steady state was approximately 5.8 L in patients with CAD.
Elimination
The terminal elimination half-life and clearance varies at different doses due to target-mediated drug disposition at lower sutimlimab-jome concentrations. The terminal elimination half-life (t½β) of sutimlimab-jome is 21 days with a clearance (CL) of approximately 0.14 L/day at the approved recommended dosage.
Metabolism
Sutimlimab-jome is a protein. It is generally recognized that antibodies are metabolized by degradation into small peptides and individual amino acids.
Specific Populations
No clinically significant differences in the pharmacokinetics of sutimlimab-jome were observed based on sex, age (19 to 88 years of age), ethnicity (Japanese, non-Japanese), and mild to moderate renal impairment (30 to 89 mL/min/1.73 m² measured by estimated glomerular filtration rate [eGFR]). The effects of severe renal impairment and hepatic impairment on the pharmacokinetics of sutimlimab-jome are unknown.
Body Weight
Population pharmacokinetic analysis shows that sutimlimab-jome AUC at steady-state decreased up to 40% for a patient weighing 110 kg following the 7.5 g dose and increased up to 170% for a patient weighing 40 kg following the 6.5 g dose as compared with a patient weighing 70 kg following the 6.5 g dose. The effect of body weight on pharmacokinetics has been integrated in the recommended dose regimen tiered by body weight.
Immunogenicity
The observed incidence of anti-drug antibodies is highly dependent on the sensitivity and specificity of the assay. Differences in assay methods preclude meaningful comparisons of the incidence of anti-drug antibodies in the studies described below with the incidence of anti-drug antibodies in other studies, including those of sutimlimab-jome or of other sutimlimab products.
During the treatment period in CARDINAL and CADENZA, 8/66 (12%) ENJAYMO-treated patients developed anti-sutimlimab-jome antibodies (duration of exposure up to 177 weeks). There was no identified clinically significant effect of anti-drug antibodies on pharmacokinetics, pharmacodynamics, safety, or effectiveness of ENJAYMO over the treatment duration [see Clinical Studies].
Clinical Studies
CADENZA
The efficacy of ENJAYMO was assessed in a placebo-controlled 6-month trial in 42 patients (CADENZA, NCT 03275454). Following the completion of the 6-month treatment period (Part A) in which 22 patients received ENJAYMO and 20 patients received placebo, 39 patients (19 patients on ENJAYMO and 20 patients on placebo) continued to receive ENJAYMO in a longÂterm safety and durability of response extension phase (Part B) for an additional 12 months following last patient out from Part A. The trial included a 9 week safety follow-up after the last dose of ENJAYMO. Patients with a confirmed diagnosis of CAD based on chronic hemolysis, polyspecific direct antiglobulin test (DAT), monospecific DAT specific for C3d, cold agglutinin titer ≥64 at 4°C, an IgG DAT ≤1+ and no history of transfusion within 6 months, or more than one blood transfusion in the 12 months prior to enrollment in the trial were administered 6.5 g or 7.5 g ENJAYMO (based on body weight) intravenously over approximately 60 minutes on Day 0, Day 7, and every 14 days thereafter; or placebo. Patients with cold agglutinin disease secondary to infection, rheumatologic disease, systemic lupus erythematosus, or overt hematologic malignancy were excluded, whereas patients with a history of or concomitant low-grade lymphoproliferative disease were not excluded.
Major baseline characteristics of the study population are summarized in Table 5.
Table 5: Baseline Characteristics of Patients Included in CADENZA
| Parameter |
Statistic |
CADENZA |
Placebo
N=20 |
ENJAYMO
N=22 |
| Age |
Mean |
68.2 |
65.3 |
|
Min, Max |
51, 83 |
46, 88 |
| Sex |
| Male |
n (%) |
4 (20.0) |
5 (22.7) |
| Female |
16 (80.0) |
17 (77.3) |
| Body weight |
Mean, Kg |
64.9 |
66.8 |
|
Min, Max |
48, 95 |
39, 100 |
| Hemoglobin |
Mean, g/dL |
9.33 |
9.15 |
| Bilirubin (total)* |
μmol/L |
35.77 (1.75 x ULN) |
41.17 (2 x ULN) |
| LDH |
U/L |
380.8 |
421.5 |
| History of transfusion Within last 6 months Within last 12 months |
Mean number of transfusions (range) |
0 0 |
0 0.14 (0, 1) |
| FACIT†-Fatigue scale |
Mean |
32.99 |
31.67 |
*Placebo N=18 and ENJAYMO N= 20 in CADENZA, for bilirubin data excluding patients with either a positive or no available test result for Gilbert’s syndrome.
†ULN: Upper limit of normal, FACIT: Functional Assessment of Chronic Illness Therapy (FACIT-Fatigue is measured on a scale of 0 (worst fatigue) to 52 (no fatigue) |
Efficacy was based on the proportion of patients who met the following criteria: an increase from baseline in Hgb level ≥1.5 g/dL at the treatment assessment time point (mean value from Weeks 23, 25, and 26), no blood transfusion from Week 5 through Week 26, and no treatment for CAD beyond what was permitted per protocol from Week 5 through Week 26. Efficacy was further assessed based on the effect of ENJAYMO on Hgb, laboratory measures of hemolysis including mean change from baseline in total bilirubin and LDH. Supportive efficacy data collected included transfusion usage after five weeks of treatment. In addition, mean change from baseline in symptoms and impacts of fatigue were assessed using a patient-reported outcome instrument, the FACIT-Fatigue (score range from 0 to 52 with higher scores indicating less fatigue).
The data from this study demonstrated a statistically significant treatment effect of ENJAYMO over placebo in terms of the rate of patients who met the efficacy criteria (responder) as well as improving symptoms and impacts of fatigue (FACIT-Fatigue). The responder rate difference between ENJAYMO and placebo was 58.78% (95% CI: 34.6% to 82.96%) with a p-value of 0.0004. At the treatment assessment timepoint (TAT), 16 of 22 patients on ENJAYMO (72.7%; 95% CI: 49.8% to 89.3%) and 3 of 20 patients on placebo (15.0%; 95% CI: 3.2% to 37.9%) met primary criteria. Efficacy of ENJAYMO in the inhibition of hemolysis in patients with CAD was demonstrated across multiple end points as described in the table below (see Table 6).
Table 6: Efficacy Results in Patients with CAD in the CADENZA Part A Study
| Parameter |
Statistic |
Placebo
N=20 |
ENJAYMO
N=22 |
Treatment Effect |
| Respondera |
n (%) |
3 (15) |
16 (72.7) |
58.78
(34.6, 82.96)b |
| p-value: |
|
|
<0.001 |
| Hemoglobin |
Mean change from baseline (LS† Mean), g/dL |
0.09 |
2.66 |
2.56 |
| 95% CI of LS Mean |
|
|
(1.75, 3.38) |
| p-value: |
|
|
<0.001 |
| Patients with mean change from baseline of: greater than or equal to 1.5 g/dL |
n (%) |
3 (15) |
16 (72.7) |
NC |
| Patients not receiving blood transfusion from Week 5 through Week 26 (transfusion avoidance) |
n (%) |
16 (80) |
18 (81.8) |
NC |
| Patients not receiving protocol-prohibited CAD medications from Week 5 through Week 26c |
n (%) |
20 (100) |
19 (86.4) |
NC |
| FACIT†-Fatigue |
Mean change from baseline (LS†Mean) |
1.91 |
10.83 |
8.93 |
| 95% CI of LS Mean |
|
|
(4, 13.85) |
| p-value: |
|
|
<0.001 |
a A responder was defined as a patient with an increase from baseline in Hgb level ≥ 1.5 g/dL at the treatment assessment time point (mean value from Weeks 23, 25, and 26), no blood transfusion from Week 5 through Week 26, and no treatment for CAD beyond what was permitted per protocol from Week 5 through Week 26.
b The Mantel-Haenszel stratum-weighted estimator of the rate difference with 95% CI was calculated using the Sato variance estimator. The stratification factors are baseline hemoglobin (< median vs ≥ median) and geographic region (Asia/Other, North America, and Europe)
c Prohibited therapies included rituximab alone or in combination with cytotoxic agents
†LS: Least Square, FACIT-Fatigue: Functional Assessment of Chronic Illness Therapy-Fatigue Scale NC= Not calculated |
During Part A, an increase in mean hemoglobin level of 2.02 g/dL was observed in patients on ENJAYMO at Week 3; in the placebo group the mean hemoglobin level decreased by 0.31g/dL. At treatment assessment timepoint, a mean decrease in bilirubin of 1.29 mg/dL compared to baseline was reported in patients on ENJAYMO (n=17) versus 0.11 mg/dL on placebo (n=18). In the ENJAYMO group, bilirubin levels normalized in 88.2% (n=15) of patients compared to 22.2% (n=4) of patients in the placebo arm. At treatment assessment timepoint, a mean decrease in LDH of 150.83 U/L compared to baseline was reported in patients on ENJAYMO (n=19) versus an increase of 7.6 U/L on placebo (n=20). In the ENJAYMO group, LDH levels were < 1.5 x ULN in 94.7% (n=18) of patients compared to 70% (n=14) in the placebo arm.
In Part B, mean hemoglobin levels were maintained at >10.5 g/dL. Sustained normalization of mean bilirubin levels was also observed indicating a sustained decrease in hemolysis. Mean hemoglobin level of 11.58 g/dL (range: 6.90-15.30) and 1.01 mg/dL (range: 0.29–5.54) for bilirubin was observed at the last on-treatment visit.
After the last dose of ENJAYMO in the study, signs and symptoms of recurrent hemolysis were observed, nine weeks after the last dose in Part B; mean hemoglobin decreased by 2.41 g/dL (SE: 0.373) and mean bilirubin increased by 1.27 mg/dL (SE: 0.182) from the last available values during treatment.
CARDINAL
The efficacy of ENJAYMO was assessed in an open-label, single-arm, 6-month trial in 24 patients (CARDINAL, NCT03347396). Following the completion of the 6-month treatment period (Part A), patients continued to receive ENJAYMO in a long-term safety and durability of response extension phase (Part B) for an additional 24 months following last patient out from Part A. The trial included a 9 week safety follow-up after the last dose of ENJAYMO.
Patients with a confirmed diagnosis of CAD based on chronic hemolysis, polyspecific direct antiglobulin test (DAT), monospecific DAT specific for C3d, cold agglutinin titer ≥64 at 4°C, and IgG DAT ≤1+ and a recent blood transfusion in the 6 months prior to enrollment were administered 6.5 g or 7.5 g ENJAYMO (based on body weight) intravenously over approximately 60 minutes on Day 0, Day 7, and every 14 days thereafter. Patients with cold agglutinin syndrome secondary to infection, rheumatologic disease, systemic lupus erythematosus, or overt hematologic malignancy were excluded, whereas patients with a history of or concomitant low-grade lymphoproliferative disease were not excluded. Major baseline characteristics of the trial population are summarized in Table 7.
Table 7: Baseline Characteristics of Patients Included in CARDINAL
| Parameter |
Statistic |
ENJAYMO
N=24 |
| Age |
Mean (SD) |
71.3 (8.2) |
|
Range |
55 to 85 years |
| Sex |
| Female |
n (%) |
15 (63) |
| Male |
|
9 (38) |
| Body weight |
Mean (SD) |
67.8 (15.8) |
|
Range |
40 to 112 kg |
| Hemoglobin |
Mean (SD), g/dL |
8.6 (1.16) |
| Bilirubin (total)* |
Mean (SD), mg/dL |
3.1 (1.41) (2.6 x ULN†) |
| LDH† |
Mean (SD), U/L |
438 (484.60) |
| Blood transfusion |
Median number of transfusions (range) |
|
| Within last 6 months |
|
2.0 (1, 19) |
| Within last 12 months |
|
2.0 (1, 23) |
* N=21 for bilirubin data excluding patients with Gilbert’s syndrome.
† ULN: Upper limit of normal, LDH: Lactate dehydrogenase. |
Efficacy was based on the proportion of patients who met the following criteria: an increase from baseline in Hgb level ≥2 g/dL or a Hgb level ≥12 g/dL at the treatment assessment time point  (mean value from Weeks 23, 25, and 26), no blood transfusion from Week 5 through Week 26, and no treatment for CAD beyond what was permitted per protocol from Week 5 through Week 26.
Efficacy of ENJAYMO in patients with CAD is described in Table 8.
Table 8: Efficacy Results in Patients with CAD in CARDINAL Part A Study
| Parameter |
Statistic |
ENJAYMO
N=24 |
| Responder* |
n (%) |
13 (54) |
| Hemoglobin level ≥12 g/dL or Increase in Hemoglobin level of ≥2 g/dL |
n (%) |
15 (63) |
| Hemoglobin level ≥12 g/dL |
n (%) |
9 (38) |
| Increase in Hemoglobin level of ≥2 g/dL |
n (%) |
15 (63) |
| Patients not receiving RBC transfusion from Week 5 through Week 26 (transfusion avoidance) |
n (%) |
17 (71) |
| Patients not receiving protocol-prohibited CAD medications† from Week 5 through Week 26 |
n (%) |
22 (92) |
* A responder was defined as a patient with an increase from baseline in Hgb level ≥2 g/dL or a Hgb level ≥12 g/dL at the treatment assessment time point (mean value from Weeks 23, 25, and 26), no blood transfusion from Week 5 through Week 26, and no treatment for CAD beyond what was permitted per protocol from Week 5 through Week 26.
† Prohibited therapies included rituximab alone or in combination with cytotoxic agents. |
In Part A, among 14 patients with baseline and follow-up bilirubin values, the mean was 3.23 mg/dL (2.7-fold ULN) at baseline and 0.91 mg/dL (0.8-fold ULN) at the treatment assessment time point. The least-squares (LS) mean change was reduction of -2.23 mg/dL (95% CI: -2.49 to -1.98). Among 17 patients with baseline and follow-up LDH values, the mean LDH was 424 U/L (1.7-fold ULN) at baseline and 301 U/L (1.2-fold ULN) at the follow-up time point. The least squared mean change in LDH at the treatment assessment time point was reduction of -126 (95% CI: -218 to -35).
In CARDINAL, an increase in mean hemoglobin level of 2.29 g/dL (SE: 0.308) was observed at Week 3 and 3.18 g/dL (SE: 0.476) at treatment assessment time point. The observed model mean change in hemoglobin level from baseline at treatment assessment time point was an improvement of 2.60 g/dL (95% CI: 0.74, 4.46).
In Part B, mean hemoglobin levels were maintained at >10 g/dL. Sustained normalization of mean bilirubin levels was also observed indicating a sustained decrease in hemolysis. Mean hemoglobin level of 12.23 g/dL (range: 9.20–14.40) and 0.96 mg/dL (range: 0.4–1.7) for bilirubin was observed at the last on-treatment visit.
After the last dose of ENJAYMO in the study, signs and symptoms of recurrent hemolysis were observed, nine weeks after the last dose in Part B; mean hemoglobin decreased by 2.28 g/dL (SE: 0.402) and mean bilirubin increased by 1.42 mg/dL (SE: 0.192) from the last available values during treatment.