Clinical Pharmacology for Jakafi
Mechanism Of Action
Ruxolitinib, a kinase inhibitor, inhibits Janus Associated Kinases (JAKs) JAK1 and JAK2 which mediate the signaling of a number of cytokines and growth factors that are important for hematopoiesis and immune function. JAK signaling involves recruitment of STATs (signal transducers and activators of transcription) to cytokine receptors, activation and subsequent localization of STATs to the nucleus leading to modulation of gene expression.
MF and PV are myeloproliferative neoplasms (MPN) known to be associated with dysregulated JAK1 and JAK2 signaling. In a mouse model of JAK2V617F-positive MPN, oral administration of ruxolitinib prevented splenomegaly, preferentially decreased JAK2V617F mutant cells in the spleen and decreased circulating inflammatory cytokines (e.g., TNF-α, IL-6).
JAK-STAT signaling pathways play a role in regulating the development, proliferation, and activation of several immune cell types important for GVHD pathogenesis. In a mouse model of aGVHD, oral administration of ruxolitinib was associated with decreased expression of inflammatory cytokines in colon homogenates and reduced immune-cell infiltration in the colon.
Pharmacodynamics
Jakafi inhibits cytokine induced STAT3 phosphorylation in whole blood from patients with MF and PV. STAT3 phosphorylation reached maximal inhibition 2 hours after Jakafi dosing and returned to near baseline by 10 hours in patients with MF and PV.
Cardiac Electrophysiology
At a dose of 1.25 to 10 times the highest recommended starting dosage, Jakafi does not prolong the QT interval to any clinically relevant extent.
Pharmacokinetics
Mean ruxolitinib maximal plasma concentration (Cmax) and AUC increased proportionally over a single dose range of 5 mg to 200 mg (4 times the approved highest recommended total daily dosage of 25 mg twice daily). Mean ruxolitinib Cmax ranged from 205 nM to 7100 nM and AUC ranged from 862 nM*hr to 30700 nM*hr over a single dose range of 5 mg to 200 mg.
Absorption
Ruxolitinib achieves Cmax within 1 hour to 2 hours post-dose. Oral absorption of ruxolitinib is estimated to be at least 95%.
Effect Of Food
No clinically relevant changes in the pharmacokinetics of ruxolitinib were observed upon administration of Jakafi with a high-fat, high-calorie meal (approximately 800 to 1000 calories of which 50% were derived from fat).
Distribution
The mean ruxolitinib volume of distribution at steady-state is 72 L (coefficient of variation [CV] 29%) in patients with MF and 75 L (23%) in patients with PV.
Protein binding of ruxolitinib is approximately 97%, mostly to albumin.
Elimination
The mean elimination half-life of ruxolitinib is approximately 3 hours and the mean elimination half-life of ruxolitinib and its metabolites is approximately 5.8 hours in healthy volunteers.
Ruxolitinib clearance (%CV) was 17.7 L/h in women and 22.1 L/h in men with MF (39%).
Ruxolitinib clearance (%CV) was 12.7 L/h (42%) in patients with PV.
Ruxolitinib clearance (%CV) was 11.8 L/h (63%) in patients with aGVHD.
Ruxolitinib clearance (%CV) was 9.7 L/h (51%) in patients with cGVHD.
Metabolism
Ruxolitinib is metabolized by CYP3A4 and to a lesser extent by CYP2C9.
Excretion
Following a single oral dose of radiolabeled ruxolitinib, 74% of radioactivity was excreted in urine and 22% via feces. Unchanged drug accounted for less than 1% of the excreted total radioactivity.
Specific Populations
No clinically relevant differences in ruxolitinib pharmacokinetics were observed based on age (12-73 years), race (White, Asian), sex, or weight (29-139 kg).
Patients With Renal Impairment
Total AUC of ruxolitinib and its active metabolites increased by 1.3-, 1.5-, 1.9-, and 1.6-fold in subjects with mild, moderate, severe renal impairment, and with ESRD after dialysis, respectively, compared to subjects with normal renal function (CLcr ≥ 90 mL/min). The change in the pharmacodynamic marker, pSTAT3 inhibition, was consistent with the corresponding increase in metabolite exposure with renal impairment. Ruxolitinib is not removed by dialysis; however, the removal of some active metabolites by dialysis cannot be ruled out.
Patients With Hepatic Impairment
No clinically relevant effect on ruxolitinib pharmacokinetics was observed based on mild to severe hepatic impairment by NCI criteria (total bilirubin > ULN and any AST) in patients with aGVHD or cGVHD.
Ruxolitinib AUC increased in subjects with mild (Child-Pugh A) by 1.9-fold, moderate (Child-Pugh B) by 1.3-fold, and severe (Child-Pugh C) hepatic impairment by 1.7-fold compared to that in subjects with normal hepatic function.
The change in the pharmacodynamic marker, pSTAT3 inhibition, was consistent with the corresponding increase in ruxolitinib exposure except in the severe hepatic impairment cohort where the pharmacodynamic activity was more prolonged in some subjects than expected based on plasma concentrations of ruxolitinib.
Patients With Liver Involvement In Graft-Versus-Host Disease
No clinically relevant effect on ruxolitinib pharmacokinetics was observed based on Stage 1, 2 or 3 liver aGVHD, or Score 1, or 2 liver cGVHD.
A lower apparent clearance of ruxolitinib was observed in patients with Stage 4 liver aGVHD compared to patients with no liver aGVHD.
The effect of Score 3 liver cGVHD on the pharmacokinetics of ruxolitinib is unknown.
Drug Interaction Studies
Clinical Studies And Model-Informed Approaches
Fluconazole
Fluconazole 100 to 400 mg once daily (a moderate CYP3A4 and CYP2C9 inhibitor) increases steady state ruxolitinib AUC by approximately 100% to 300% [see DOSAGE AND ADMINISTRATION and DRUG INTERACTIONS].
Strong CYP3A4 Inhibitors
Ketoconazole (strong CYP3A4 inhibitor) increased ruxolitinib Cmax by 33% and AUC by 91% and prolonged ruxolitinib half-life from 3.7 hours to 6 hours [see DOSAGE AND ADMINISTRATION and DRUG INTERACTIONS].
Moderate CYP3A4 Inhibitors
Erythromycin (moderate CYP3A4 inhibitor) increased ruxolitinib Cmax by 8% and AUC by 27% [see DRUG INTERACTIONS].
Strong CYP3A4 Inducers
Rifampin (strong CYP3A4 inducer) decreased ruxolitinib Cmax by 32% and AUC by 61%. The relative exposure to ruxolitinib’s active metabolites increased approximately 100% [see DRUG INTERACTIONS].
In Vitro Studies
Cytochrome P450 (CYP) Enzymes
Ruxolitinib and its M18 metabolite did not inhibit CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4. Ruxolitinib did not induce CYP1A2, CYP2B6 or CYP3A4 at clinically relevant concentrations.
Transporter Systems
Ruxolitinib and its M18 metabolite did not inhibit the P-gp, BCRP, OATP1B1, OATP1B3, OCT1, OCT2, OAT1 or OAT3 at clinically relevant concentrations. Ruxolitinib was not a P-gp substrate.
Clinical Studies
Myelofibrosis
Two randomized Phase 3 studies (Studies 1 and 2) were conducted in patients with MF (either primary MF, post-polycythemia vera MF or post-essential thrombocythemia-MF). In both studies, patients had palpable splenomegaly at least 5 cm below the costal margin and risk category of intermediate 2 (2 prognostic factors) or high risk (3 or more prognostic factors) based on the International Working Group Consensus Criteria (IWG).
The starting dose of Jakafi was based on platelet count. Patients with a platelet count between 100 and 200 × 109/L were started on Jakafi 15 mg twice daily and patients with a platelet count greater than 200 × 109/L were started on Jakafi 20 mg twice daily. Doses were then individualized based upon tolerability and efficacy with maximum doses of 20 mg twice daily for patients with platelet counts between 100 to less than or equal to 125 × 109/L, of 10 mg twice daily for patients with platelet counts between 75 to less than or equal to 100 × 109/L, and of 5 mg twice daily for patients with platelet counts between 50 to less than or equal to 75 × 109/L.
Study 1
Study 1 (NCT00952289) was a double-blind, randomized, placebo-controlled study in 309 patients who were refractory to or were not candidates for available therapy. The median age was 68 years (range 40 to 91 years) with 61% of patients older than 65 years and 54% were male. Fifty percent (50%) of patients had primary MF, 31% had post-polycythemia vera MF and 18% had post-essential thrombocythemia MF. Twenty-one percent (21%) of patients had red blood cell transfusions within 8 weeks of enrollment in the study. The median hemoglobin count was 10.5 g/dL and the median platelet count was 251 × 109/L. Patients had a median palpable spleen length of 16 cm below the costal margin, with 81% having a spleen length 10 cm or greater below the costal margin. Patients had a median spleen volume as measured by magnetic resonance imaging (MRI) or computed tomography (CT) of 2595 cm3 (range 478 cm3 to 8881 cm3). (The upper limit of normal is approximately 300 cm3).
Patients were dosed with Jakafi or matching placebo. The primary efficacy endpoint was the proportion of patients achieving greater than or equal to a 35% reduction from baseline in spleen volume at Week 24 as measured by MRI or CT.
Secondary endpoints included duration of a 35% or greater reduction in spleen volume and proportion of patients with a 50% or greater reduction in Total Symptom Score from baseline to Week 24 as measured by the modified Myelofibrosis Symptom Assessment Form (MFSAF) v2.0 diary.
Study 2
Study 2 (NCT00934544) was an open-label, randomized study in 219 patients. Patients were randomized 2:1 to Jakafi versus best available therapy. Best available therapy was selected by the investigator on a patient-by-patient basis. In the best available therapy arm, the medications received by more than 10% of patients were hydroxyurea (47%) and glucocorticoids (16%). The median age was 66 years (range 35 to 85 years) with 52% of patients older than 65 years and 57% were male. Fifty-three percent (53%) of patients had primary MF, 31% had postÂpolycythemia vera MF and 16% had post-essential thrombocythemia MF. Twenty-one percent (21%) of patients had red blood cell transfusions within 8 weeks of enrollment in the study. The median hemoglobin count was 10.4 g/dL and the median platelet count was 236 × 109/L. Patients had a median palpable spleen length of 15 cm below the costal margin, with 70% having a spleen length 10 cm or greater below the costal margin. Patients had a median spleen volume as measured by MRI or CT of 2381 cm3 (range 451 cm3 to 7765 cm3).
The primary efficacy endpoint was the proportion of patients achieving 35% or greater reduction from baseline in spleen volume at Week 48 as measured by MRI or CT.
A secondary endpoint in Study 2 was the proportion of patients achieving a 35% or greater reduction of spleen volume as measured by MRI or CT from baseline to Week 24.
Study 1 And 2 Efficacy Results
Efficacy analyses of the primary endpoint in Studies 1 and 2 are presented in Table 20 below. A significantly larger proportion of patients in the Jakafi group achieved a 35% or greater reduction in spleen volume from baseline in both studies compared to placebo in Study 1 and best available therapy in Study 2. A similar proportion of patients in the Jakafi group achieved a 50% or greater reduction in palpable spleen length.
Table 20: Percent of Patients with Myelofibrosis Achieving 35% or Greater Reduction from Baseline in Spleen Volume at Week 24 in Study 1 and at Week 48 in Study 2 (Intent to Treat)
|
Study 1 |
Study 2 |
Jakafi
(N=155) |
Placebo
(N=154) |
Jakafi
(N=146) |
Best Available Therapy
(N=73) |
| Time Points |
Week 24 |
Week 48 |
| Number (%) of Patients with Spleen Volume Reduction by 35% or More |
65 (42) |
1 (< 1) |
41 (29) |
0 |
| P-value |
< 0.0001 |
< 0.0001 |
Figure 1 shows the percent change from baseline in spleen volume for each patient at Week 24 (Jakafi N=139, placebo N=106) or the last evaluation prior to Week 24 for patients who did not complete 24 weeks of randomized treatment (Jakafi N=16, placebo N=47). One (1) patient (placebo) with a missing baseline spleen volume is not included.
Figure 1: Percent Change from Baseline in Spleen Volume at Week 24 or Last Observation for Each Patient (Study 1)
In Study 1, MF symptoms were a secondary endpoint and were measured using the modified Myelofibrosis Symptom Assessment Form (MFSAF) v2.0 diary. The modified MFSAF is a daily diary capturing the core symptoms of MF (abdominal discomfort, pain under left ribs, night sweats, itching, bone/muscle pain and early satiety). Symptom scores ranged from 0 to 10 with 0 representing symptoms “absent” and 10 representing “worst imaginable” symptoms. These scores were added to create the daily total score, which has a maximum of 60.
Table 21 presents assessments of Total Symptom Score from baseline to Week 24 in Study 1 including the proportion of patients with at least a 50% reduction (ie, improvement in symptoms). At baseline, the mean Total Symptom Score was 18.0 in the Jakafi group and 16.5 in the placebo group. A higher proportion of patients in the Jakafi group had a 50% or greater reduction in Total Symptom Score than in the placebo group, with a median time to response of less than 4 weeks.
Table 21: Improvement in Total Symptom Score in Patients with Myelofibrosis
|
Jakafi
(N=148) |
Placebo
(N=152) |
| Number (%) of Patients with 50% or Greater Reduction in Total Symptom Score by Week 24 |
68 (46) |
8 (5) |
| P-value |
< 0.0001 |
Figure 2 shows the percent change from baseline in Total Symptom Score for each patient at Week 24 (Jakafi N=129, placebo N=103) or the last evaluation on randomized therapy prior to Week 24 for patients who did not complete 24 weeks of randomized treatment (Jakafi N=16, placebo N=42). Results are excluded for 5 patients with a baseline Total Symptom Score of zero, 8 patients with missing baseline and 6 patients with insufficient post-baseline data.
Figure 2: Percent Change from Baseline in Total Symptom Score at Week 24 or Last Observation for Each Patient (Study 1)
Figure 3 displays the proportion of patients with at least a 50% improvement in each of the individual symptoms that comprise the Total Symptom Score indicating that all 6 of the symptoms contributed to the higher Total Symptom Score response rate in the group treated with Jakafi.
Figure 3: Proportion of Patients with Myelofibrosis Achieving 50% or Greater Reduction in Individual Symptom Scores at Week 24
An exploratory analysis of patients receiving Jakafi also showed improvement in fatigue-related symptoms (i.e., tiredness, exhaustion, mental tiredness, and lack of energy) and associated impacts on daily activities (i.e., activity limitations related to work, self-care, and exercise) as measured by the PROMIS® Fatigue 7-item short form total score at Week 24. Patients who achieved a reduction of 4.5 points or more from baseline to Week 24 in the PROMIS® Fatigue total score were considered to have achieved a fatigue response. Fatigue response was reported in 35% of patients in the Jakafi group versus 14% of the patients in the placebo group.
Overall survival was a secondary endpoint in both Study 1 and Study 2. Patients in the control groups were eligible for crossover in both studies, and the median times to crossover were 9 months in Study 1 and 17 months in Study 2.
Figure 4 and Figure 5 show Kaplan-Meier curves of overall survival at prospectively planned analyses after all patients remaining on study had completed 144 weeks on study.
Figure 4: Overall Survival -Kaplan-Meier Curves by Treatment Group in Study 1
Figure 5: Overall Survival -Kaplan-Meier Curves by Treatment Group in Study 2
Polycythemia Vera
Study 3 (NCT01243944) was a randomized, open-label, active-controlled Phase 3 study conducted in 222 patients with PV. Patients had been diagnosed with PV for at least 24 weeks, had an inadequate response to or were intolerant of hydroxyurea, required phlebotomy and exhibited splenomegaly. All patients were required to demonstrate hematocrit control between 40-45% prior to randomization. The age ranged from 33 to 90 years with 30% of patients over 65 years of age and 66% were male. Patients had a median spleen volume as measured by MRI or CT of 1272 cm3 (range 254 cm3 to 5147 cm3) and median palpable spleen length below the costal margin was 7 cm.
Patients were randomized to Jakafi or best available therapy. The starting dose of Jakafi was 10 mg twice daily. Doses were then individualized based upon tolerability and efficacy with a maximum dose of 25 mg twice daily. At Week 32, 98 patients were still on Jakafi with 8% receiving greater than 20 mg twice daily, 15% receiving 20 mg twice daily, 33% receiving 15 mg twice daily, 34% receiving 10 mg twice daily, and 10% receiving less than 10 mg twice daily. Best available therapy (BAT) was selected by the investigator on a patient-by-patient basis and included hydroxyurea (60%), interferon/pegylated interferon (12%), anagrelide (7%), pipobroman (2%), lenalidomide/thalidomide (5%), and observation (15%).
The primary endpoint was the proportion of subjects achieving a response at Week 32, with response defined as having achieved both hematocrit control (the absence of phlebotomy eligibility beginning at the Week 8 visit and continuing through Week 32) and spleen volume reduction (a greater than or equal to 35% reduction from baseline in spleen volume at Week 32). Phlebotomy eligibility was defined as a confirmed hematocrit greater than 45% that is at least 3 percentage points higher than the hematocrit obtained at baseline or a confirmed hematocrit greater than 48%, whichever was lower. Secondary endpoints included the proportion of all randomized subjects who achieved the primary endpoint and who maintained their response 48 weeks after randomization, and the proportion of subjects achieving complete hematological remission at Week 32 with complete hematological remission defined as achieving hematocrit control, platelet count less than or equal to 400 × 109/L, and white blood cell count less than or equal to 10 × 109/L.
Results of the primary and secondary endpoints are presented in Table 22. A significantly larger proportion of patients on the Jakafi arm achieved a response for the primary endpoint compared to best available therapy at Week 32 and maintained their response 48 weeks after randomization. A significantly larger proportion of patients on the Jakafi arm compared to best available therapy also achieved complete hematological remission at Week 32.
Table 22: Percent of Patients with Polycythemia Vera Achieving the Primary and Key Secondary Endpoints in Study 3 (Intent to Treat)
|
Jakafi
(N=110) |
Best Available Therapy
(N=112) |
| Number (%) of Patients Achieving a Primary Response at Week 32 |
25 (23%) |
1 (< 1%) |
| 95% CI of the response rate (%) |
(15%, 32%) |
(0%, 5%) |
| P-value |
< 0.0001 |
| Number (%) of Patients Achieving a Durable Primary Response at Week 48 |
22 (20%) |
1 (< 1%) |
| 95% CI of the response rate (%) |
(13%, 29%) |
(0%, 5%) |
| P-value |
< 0.0001 |
| Number (%) of Patients Achieving Complete Hematological Remission at Week 32 |
26 (24%) |
9 (8%) |
| 95% CI of the response rate (%) |
(16%, 33%) |
(4%, 15%) |
| P-value |
0.0016 |
| Primary Response defined as having achieved both the absence of phlebotomy eligibility beginning at the Week 8 visit and continuing through Week 32 and a greater than or equal to 35% reduction from baseline in spleen volume at Week 32. |
Additional analyses for Study 3 to assess durability of response were conducted at Week 80 only in the Jakafi arm. On this arm, 91 (83%) patients were still on treatment at the time of the Week 80 data cut-off. Of the 25 patients who achieved a primary response at Week 32, 19 (76% of the responders) maintained their response through Week 80, and of the 26 patients who achieved complete hematological remission at Week 32, 15 (58% of the responders) maintained their response through Week 80.
In an assessment of the individual components that make up the primary endpoint, there were 66 (60%) patients with hematocrit control on the Jakafi arm vs. 21 (19%) patients on best available therapy at Week 32; 51 (77% of hematocrit responders) patients on the Jakafi arm maintained hematocrit control through Week 80. There were 44 (40%) patients with spleen volume reduction from baseline greater than or equal to 35% on the Jakafi arm vs. 1 (< 1%) patient on best available therapy at Week 32; 43 (98% of spleen volume reduction responders) patients on the Jakafi arm maintained spleen volume reduction through Week 80.
Acute Graft-Versus-Host Disease
Study 4 (NCT02953678) was an open-label, single-arm, multicenter study of Jakafi for treatment of patients with steroid-refractory aGVHD Grades 2 to 4 (Mount Sinai Acute GVHD International Consortium (MAGIC) criteria) occurring after allogeneic hematopoietic stem cell transplantation. Jakafi was administered at 5 mg twice daily, and the dose could be increased to 10 mg twice daily after 3 days in the absence of toxicity.
There were 49 patients with aGVHD refractory to steroids alone. These patients had a median age of 57 years (range, 18-72 years), 47% were male, 92% were Caucasian, and 14% were Hispanic. At baseline, aGVHD was Grade 2 in 27%, Grade 3 in 55%, and Grade 4 in 18%; 84% had visceral GVHD; the median MAGIC biomarker score was 0.47 (range, 0.10-0.92); and the median ST2 level was 334 mcg/L (range, 55-1286 mcg/L). The median duration of prior corticosteroid exposure at baseline was 15 days (range: 3 – 106 days).
The efficacy of Jakafi was based on Day-28 overall response rate (ORR) (complete response, very good partial response or partial response by Center for International Blood and Marrow Transplant Research (CIBMTR) criteria) and the duration of response. The ORR results are presented in Table 23; Day-28 ORR was 100% for Grade 2 GVHD, 40.7% for Grade 3 GVHD, and 44.4% for Grade 4 GVHD.
The median duration of response, calculated from Day-28 response to progression, new salvage therapy for aGVHD or death from any cause (with progression being defined as worsening by one stage in any organ without improvement in other organs in comparison to prior response assessment) was 16 days (95% CI 9, 83). Also, for the Day-28 responders, the median time from Day-28 response to either death or need for new therapy for aGVHD (additional salvage therapy or increase in steroids) was 173 days (95% CI 66, NE).
Table 23: Day-28 Overall Response Rate for Patients with Steroid-Refractory Acute GVHD in Study 4
|
Refractory to Steroids Alone
(n=49) |
| Overall Response (%) (95% CI) |
28 (57.1%) (42.2, 71.2) |
| Complete Response |
15 (30.6%) |
| Very Good Partial Response |
2 (4.1%) |
| Partial Response |
11 (22.4%) |
Chronic Graft-Versus-Host Disease
Study 5 (REACH-3; NCT03112603) was a randomized, open-label, multicenter study of Jakafi in comparison to best available therapy (BAT) for treatment of corticosteroid-refractory cGVHD after allogeneic stem cell transplantation. Eligible patients were ≥ 12 years old with moderate or severe cGVHD as defined by NIH Consensus Criteria requiring additional therapy after failure of corticosteroid therapy and no more than one additional salvage treatment. Patients were excluded if they had ANC < 1 Gi/L and platelet count < 25 Gi/L, estimated creatinine clearance < 30 ml/min, progressive onset cGVHD, oxygen saturation < 90%, total bilirubin > 2 mg/dL, or diarrhea due to GVHD.
A total of 329 patients were randomized 1:1 to receive either Jakafi 10 mg twice daily (n=165) or BAT (n=164). BAT was selected by the investigator prior to randomization and included the following treatments: extracorporeal photopheresis (ECP), low-dose methotrexate (MTX), mycophenolate mofetil (MMF), mTOR inhibitors (everolimus or sirolimus), infliximab, rituximab, pentostatin, imatinib, or ibrutinib. Randomization was stratified by cGVHD severity (moderate versus severe). On Cycle 7 Day 1 and thereafter, patients randomized to BAT could cross over to Jakafi if they had disease progression, mixed response, unchanged response, cGVHD flare, or toxicity to BAT. All patients also received standard supportive care, including anti-infective medications. GVHD prophylaxis and cGVHD treatment medications initiated before randomization, including systemic corticosteroids, calcineurin inhibitors, and topical or inhaled corticosteroid therapy, were allowed to be continued per institutional guidelines. Table 24 shows the demographics and baseline disease characteristics of the randomized population.
Table 24: REACH-3: Demographics and Baseline Chronic GVHD Characteristics
|
Jakafi
(N=165) |
Best Available Therapy
(N=164) |
| Median Age, Years (range) |
49 (13, 73) |
50 (12, 76) |
| Age 12 to < 18 Year, n (%) |
4 (2) |
8 (5) |
| Age > 65 Years, n (%) |
18 (11) |
22 (13) |
| Male, n (%) |
109 (66) |
92 (56) |
| Race, n (%) |
| White |
116(70) |
132 (81) |
| Black |
2 (1) |
0 |
| Asian |
33 (20) |
21 (13) |
| American Indian or Alaska native |
2 (1) |
0 |
| Other |
9 (6) |
4 (2) |
| Unknown |
3 (2) |
7 (4) |
| Median (range) time (days) from cGVHD diagnosis to randomization |
174 (7-2017) |
150 (10-1947) |
| Prior Therapy |
| No prior treatment for cGVHD |
2 (1) |
1 (1) |
| Failed first-line steroids alone |
115 (70) |
125 (76) |
| Failed first-line combination including steroids |
42 (25) |
30 (18) |
| Failed two lines of therapy |
6 (4) |
8 (5) |
| ≥ 4 Organs involved, n (%) |
67 (41) |
63 (38) |
| Severe cGVHD, n (%) |
86 (52) |
79 (48) |
| Median (range) cGVHD Total Symptom Score |
19 (0-80) |
18 (1-54) |
| Median (range) corticosteroid dose at baseline (PE mg/kg)a |
0.29 (0.01-1.81) |
0.26 (0.06-1.21) |
| a Prednisone equivalent milligrams/kilogram |
The efficacy of Jakafi was based on overall response rate (ORR) through Cycle 7 Day 1, where overall response included complete response or partial response according to the 2014 NIH Response Criteria and durability of the response. The ORR results are presented in Table 25; the difference in ORR between Jakafi and BAT arms was 13% (95% CI 3%, 23%). The median time to first response in the responders was 3 weeks (range, 2 to 24) for the Jakafi arm and 4 weeks (range, 2 to 25) for the BAT arm. The median duration of response, calculated from first response to progression, death, or new systemic therapies for cGVHD, was 4.2 months (95% CI 3.2, 6.7) for the Jakafi arm and 2.1 months (95% CI 1.6, 3.2) for the BAT arm; and the median time from first response to death or new systemic therapies for cGVHD was 25 months (95% CI 16.8, NE) for the Jakafi arm and 5.6 months (95% CI 4.1, 7.8) for the BAT arm.
Table 25: Overall Response Rate through Cycle 7 Day 1 for Patients with Chronic GVHD in Study 5
|
Jakafi
(N=165) |
Best Available Therapy
(N=164) |
| Overall Response (%) |
116 (70%) |
94 (57%) |
| (95% CI)a |
(63%, 77%) |
(49%, 65%) |
| Complete Response (%) |
14 (8%) |
8 (5%) |
| Partial Response (%) |
102 (62%) |
86 (52%) |
| a 95% CI of Overall Response Rate is estimated using Clopper-Pearson method. |
ORR results were supported by exploratory analyses of patient-reported symptom severity which showed at least a 7-point decrease in the cGVHD Total Symptom Score at any time through Cycle 7 Day 1 in 66 (40%; 95% CI 32, 48) patients in the Jakafi arm and 47 (29%; 95% CI 22, 36) patients in the BAT arm.