Pharmacotherapeutic group: Antineoplastic agents, protein kinase inhibitors, ATC code: L01EJ01
Mechanism of action
Ruxolitinib is a selective inhibitor of the Janus Associated Kinases (JAKs) JAK1 and JAK2 (IC50 values of 3.3 nM and 2.8 nM for JAK1 and JAK2 enzymes, respectively). These mediate the signalling of a number of cytokines and growth factors that are important for haematopoiesis and immune function.
MF and PV are myeloproliferative neoplasms known to be associated with dysregulated JAK1 and JAK2 signalling. The basis for the dysregulation is believed to include high levels of circulating cytokines that activate the JAK‑STAT pathway, gain‑of‑function mutations such as JAK2V617F, and silencing of negative regulatory mechanisms. MF patients exhibit dysregulated JAK signalling regardless of JAK2V617F mutation status. Activating mutations in JAK2 (V617F or exon 12) are found in >95% of PV patients.
Ruxolitinib inhibits JAK‑STAT signalling and cell proliferation of cytokine‑dependent cellular models of haematological malignancies, as well as of Ba/F3 cells rendered cytokine‑independent by expressing the JAK2V617F mutated protein, with IC50 ranging from 80‑320 nM.
JAK-STAT signalling pathways play a role in regulating the development, proliferation, and activation of several immune cell types important for GvHD pathogenesis.
Pharmacodynamic effects
Ruxolitinib inhibits cytokine-induced STAT3 phosphorylation in whole blood from healthy subjects, MF patients and PV patients. Ruxolitinib resulted in maximal inhibition of STAT3 phosphorylation 2 hours after dosing which returned to near baseline by 8 hours in both healthy subjects and MF patients, indicating no accumulation of either parent or active metabolites.
Baseline elevations in inflammatory markers associated with constitutional symptoms such as TNFα, IL‑6 and CRP in subjects with MF were decreased following treatment with ruxolitinib. MF patients did not become refractory to the pharmacodynamic effects of ruxolitinib treatment over time. Similarly, patients with PV also presented with baseline elevations in inflammatory markers and these markers were decreased following treatment with ruxolitinib.
In a thorough QT study in healthy subjects, there was no indication of a QT/QTc prolonging effect of ruxolitinib in single doses up to a supratherapeutic dose of 200 mg, indicating that ruxolitinib has no effect on cardiac repolarisation.
Clinical efficacy and safety
Myelofibrosis
Two randomised phase 3 studies (COMFORT‑I and COMFORT‑II) were conducted in patients with MF (primary MF, post‑polycythaemia vera MF or post‑essential thrombocythaemia MF). In both studies, patients had palpable splenomegaly at least 5 cm below the costal margin and risk category of intermediate‑2 or high risk based on the International Working Group (IWG) Consensus Criteria. The starting dose of Jakavi was based on platelet count. Patients with platelet counts ≤100,000/mm3 were not eligible for enrolment in COMFORT studies but 69 patients were enrolled in the EXPAND study, a Phase Ib, open label, dose-finding study in patients with MF (primary MF, post‑polycythaemia vera MF or post‑essential thrombocythaemia MF) and baseline platelet counts ≥50,000 and <100,000/mm3.
COMFORT‑I was a double‑blind, randomised, placebo‑controlled study in 309 patients who were refractory to or were not candidates for available therapy. The primary efficacy endpoint was proportion of subjects achieving ≥35% reduction from baseline in spleen volume at week 24 as measured by Magnetic Resonance Imaging (MRI) or Computed Tomography (CT).
Secondary endpoints included duration of maintenance of a ≥35% reduction from baseline in spleen volume, proportion of patients who had ≥50% reduction in total symptom score, changes in total symptom scores from baseline to week 24, as measured by the modified MF Symptom Assessment Form (MFSAF) v2.0 diary, and overall survival.
COMFORT‑II was an open‑label, randomised study in 219 patients. Patients were randomised 2:1 to ruxolitinib versus best available therapy. In the best available therapy arm, 47% of patients received hydroxyurea and 16% of patients received glucocorticoids. The primary efficacy endpoint was proportion of patients achieving ≥35% reduction from baseline in spleen volume at week 48 as measured by MRI or CT.
Secondary endpoints included proportion of patients achieving a ≥35% reduction of spleen volume from baseline at week 24 and duration of maintenance of a ≥35% reduction from baseline spleen volume.
In COMFORT‑I and COMFORT‑II, patient baseline demographics and disease characteristics were comparable between the treatment arms.
Table 9 Percentage of patients with ≥35% reduction from baseline in spleen volume at week 24 in COMFORT‑I and at week 48 in COMFORT‑II (ITT)
| | COMFORT‑I | COMFORT‑II |
| | Jakavi (N=155) | Placebo (N=153) | Jakavi (N=144) | Best available therapy (N=72) |
| Time points | Week 24 | Week 48 |
| Number (%) of subjects with spleen volume reduced by ≥35% | 65 (41.9) | 1 (0.7) | 41 (28.5) | 0 |
| 95% confidence intervals | 34.1, 50.1 | 0, 3.6 | 21.3, 36.6 | 0.0, 5.0 |
| p‑value | <0.0001 | <0.0001 |
A significantly higher proportion of patients in the Jakavi group achieved ≥35% reduction from baseline in spleen volume (Table 9) regardless of the presence or absence of the JAK2V617F mutation or the disease subtype (primary MF, post‑polycythaemia vera MF, post‑essential thrombocythaemia MF).
Table 10 Percentage of patients with ≥35% reduction from baseline in spleen volume by JAK mutation status (safety set)
| | COMFORT‑I | COMFORT‑II |
| | Jakavi | Placebo | Jakavi | Best available therapy |
| JAK mutation status | Positive (N=113) n (%) | Negative (N=40) n (%) | Positive (N=121) n (%) | Negative (N=27) n (%) | Positive (N=110) n (%) | Negative (N=35) n (%) | Positive (N=49) n (%) | Negative (N=20) n (%) |
| Number (%) of subjects with spleen volume reduced by ≥35% | 54 (47.8) | 11 (27.5) | 1 (0.8) | 0 | 36 (32.7) | 5 (14.3) | 0 | 0 |
| Time point | After 24 weeks | After 48 weeks |
The probability of maintaining spleen response (≥35% reduction) to Jakavi for at least 24 weeks was 89% in COMFORT‑I and 87% in COMFORT‑II; 52% maintained spleen responses for at least 48 weeks in COMFORT‑II.
In COMFORT‑I, 45.9% subjects in the Jakavi group achieved a ≥50% improvement from baseline in the week 24 total symptom score (measured using MFSAF diary v2.0), as compared to 5.3% in the placebo group (p<0.0001 using chi-square test). The mean change in the global health status at week 24, as measured by EORTC QLQ C30 was +12.3 for Jakavi and ‑3.4 for placebo (p<0.0001).
In COMFORT-I, after a median follow-up of 34.3 months, the death rate in patients randomised to the ruxolitinib arm was 27.1% versus 35.1% in patients randomised to placebo; HR 0.687; 95% CI 0.459 ‑ 1.029; p=0.0668.
In COMFORT-I, after a median follow–up of 61.7 months, the death rate in patients randomised to the ruxolitinib arm was 44.5% (69 of 155 patients) versus 53.2% (82 of 154) in patients randomised to placebo. There was a 31% reduction in the risk of death in the ruxolitinib arm as compared to placebo (HR 0.69; 95% CI 0.50 - 0.96; p=0.025).
In COMFORT-II, after a median follow‑up of 34.7 months, the death rate in patients randomised to ruxolitinib was 19.9% versus 30.1% in patients randomised to best available treatment (BAT); HR 0.48; 95% CI 0.28 ‑ 0.85; p=0.009. In both studies, the lower death rates noted in the ruxolitinib arm were predominantly driven by the results obtained in the post polycythaemia vera and post essential thrombocythaemia subgroups.
In COMFORT-II, after a median follow-up of 55.9 months, the death rate in patients randomised to the ruxolitinib arm was 40.4% (59 of 146 patients) versus 47.9% (35 of 73 patients) in patients randomized to best available therapy (BAT). There was a 33% reduction in risk of death in the ruxolitinib arm compared to the BAT arm (HR 0.67; 95% CI 0.44 - 1.02; p=0.062).
Polycythaemia vera
A randomised, open-label, active-controlled phase 3 study (RESPONSE) was conducted in 222 patients with PV who were resistant to or intolerant of hydroxyurea defined based on the European LeukemiaNet (ELN) international working group published criteria. 110 patients were randomised to the ruxolitinib arm and 112 patients to the BAT arm. The starting dose of Jakavi was 10 mg twice daily. Doses were then adjusted in individual patients based on tolerability and efficacy with a maximum dose of 25 mg twice daily. BAT was selected by the investigator on a patient-by-patient basis and included hydroxyurea (59.5%), interferon/pegylated interferon (11.7%), anagrelide (7.2%), pipobroman (1.8%) and observation (15.3%).
Baseline demographics and disease characteristics were comparable between the two treatments arms. The median age was 60 years (range 33 to 90 years). Patients in the ruxolitinib arm had PV diagnosis for a median of 8.2 years and had previously received hydroxyurea for a median of approximately 3 years. Most patients (>80%) had received at least two phlebotomies in the last 24 weeks prior to screening. Comparative data regarding long-term survival and incidence of disease complications is missing.
The primary composite endpoint was the proportion of patients achieving both an absence of phlebotomy eligibility (HCT control) and a ≥35% reduction in spleen volume from baseline at week 32. Phlebotomy eligibility was defined as a confirmed HCT of >45%, i.e. at least 3 percentage points higher than the HCT obtained at baseline or a confirmed HCT of >48%, depending on which was lower. Key secondary endpoints included the proportion of patients who achieved the primary endpoint and remained free from progression at week 48, as well as the proportion of patients achieving complete haematological remission at week 32.
The study met its primary objective and a higher proportion of patients in the Jakavi group achieved the primary composite endpoint and each of its individual components. Significantly more patients treated with Jakavi (23%) achieved a primary response (p<0.0001) compared to BAT (0.9%). Haematocrit control was achieved in 60% of patients in the Jakavi arm compared to 18.8% in the BAT arm and a ≥35% reduction in spleen volume was achieved in 40% of patients in the Jakavi arm compared to 0.9% in the BAT arm (Figure 1).
Both key secondary endpoints were also met. The proportion of patients achieving a complete haematological remission was 23.6% on Jakavi compared to 8.0% on BAT (p=0.0013) and the proportion of patients achieving a durable primary response at week 48 was 20% on Jakavi and 0.9% on BAT (p<0.0001).
Figure 1 Patients achieving the primary endpoint and components of the primary endpoint at week 32
Symptom burden was assessed using the MPN-SAF total symptom score (TSS) electronic patient diary, which consisted of 14 questions. At week 32, 49% and 64% of patients treated with ruxolitinib achieved a ≥50% reduction in TSS-14 and TSS-5, respectively, compared to only 5% and 11% of patients on BAT.
Treatment benefit perception was measured by the Patient Global Impression of Change (PGIC) questionnaire. 66% of patients treated with ruxolitinib compared to 19% treated with BAT reported an improvement as early as four weeks after beginning treatment. Improvement in perception of treatment benefit was also higher in patients treated with ruxolitinib at week 32 (78% versus 33%).
Additional analyses from the RESPONSE study to assess durability of response were conducted at week 80 and week 256 following randomisation. Out of 25 patients who had achieved primary response at week 32, 3 patients had progressed by week 80 and 6 patients by week 256. The probability to have maintained a response from week 32 up to week 80 and week 256 was 92% and 74%, respectively (see Table 11).
Table 11 Durability of primary response in the RESPONSE study
| | Week 32 | Week 80 | Week 256 |
| Primary response achieved at week 32* n/N (%) | 25/110 (23%) | n/a | n/a |
| Patients maintaining primary response | n/a | 22/25 | 19/25 |
| Probability of maintaining primary response | n/a | 92% | 74% |
| * According to the primary response composite endpoint criteria: absence of phlebotomy eligibility (HCT control) and a ≥35% reduction in spleen volume from baseline. n/a: not applicable |
A second randomised, open label, active-controlled phase 3b study (RESPONSE 2) was conducted in 149 PV patients who were resistant to, or intolerant of, hydroxyurea but without palpable splenomegaly. The primary endpoint defined as the proportion of patients achieving HCT control (absence of phlebotomy eligibility) at week 28 was met (62.2% in the Jakavi arm versus 18.7% in the BAT arm). The key secondary endpoint defined as the proportion of patients achieving complete haematological remission at week 28 was also met (23.0% in the Jakavi arm versus 5.3% in the BAT arm).
Graft-versus-host disease
Acute graft-versus-host disease
In REACH-1, 71 patients (≥ 12 years) with grade II to IV corticosteroid-refractory acute GvHD (Mount Sinai Acute GvHD International Consortium (MAGIC) criteria) received open-label Jakavi at a dose of 5 mg twice daily. Corticosteroid refractoriness was determined when patients had progression after at least 3 days, failed to achieve a response after 7 days or failed corticosteroid taper.
Participants began oral administration of ruxolitinib at 5 mg BID; if hematologic parameters were stable and no treatment-related toxicity was observed after the first 3 days of treatment, the dose could be increased to 10 mg BID.
In addition to Jakavi, patients could have received standard allogeneic stem cell transplantation supportive care including anti-infective medicinal products and transfusion support.
At baseline, acute GvHD was grade II in 31.0%, Grade III in 46.5%, and Grade IV in 22.5%. Approximately half of the participants (52.1%) had at least 2 organs involved at baseline with distribution across the lower GI tract (71.8%), skin (50.7%), upper GI tract (31.0%), and liver (22.5%).71.8% had lower GI-tract and skin (50.7% involvement). Majority (80.3%) of them had peripheral blood stem cell (PBSC) transplants and from identical HLA-matched donors (63.4%).
The median time since alloSCT was 74.0 days, and the median time since acute GvHD diagnosis was 17.0 days. The median duration of study treatment as of the final analysis data cut-off date (05-Jun-2019) was 46.0 days, and 18 patients (25.4%) received ruxolitinib for more than 180 days.
The median age of participants was 58 years (range: 18-73 years), 49.3% were males and 50.7% were females, and 93.0% of participants were white/Caucasian. Approximately 60.6% of the participants had baseline ECOG performance status of 2 or higher, with 25.4% at 3 or higher.
All 71 participants had received prior systemic therapy with corticosteroids for the treatment of GVHD. The median duration of prior corticosteroid exposure was 16.0 days, and the median average daily dose of corticosteroids at the start of study treatment was 156.25 mg/day. In addition to prior corticosteroid treatment, 23.9% of participants had received calcineurin inhibitors, with or without methotrexate). The most common reasons for discontinuation of the most recent prior acute GVHD therapy were PD and lack of efficacy.
The primary endpoint of REACH1 was the overall response rate (ORR) on Day 28, defined as the proportion of patients in each arm with a complete response (CR), very good partial response (VGPR) or a partial response (PR) as per the CIBMTR modifications to the IBMTR response index.
The REACH 1 study achieved the predetermined threshold for a positive study outcome (lower limit of the 95% CI for Day 28 ORR ≥ 40%). Forty participants (56.3% [95% CI: 44.0, 68.1]) demonstrated a response at Day 28, including 19 participants (26.8%) who achieved a CR, 6 participants who achieved a VGPR (8.5%) and 15 participants who achieved a PR (21.1%). Of the participants who had a response on Day 28, 19 of 40 participants had a CR (26.8%). The best ORR, defined as the proportion of participants demonstrating a response at any timepoint, was 76.1% (95% CI: 64.5, 85.4). The majority of participants (62.0%) achieved their first response within the first 14 days of treatment, with a median time to first response of 8 days; all first responses were achieved before Day 56.
Table 12 Day-28 Overall response rate
| | Ruxolitinib (N=71) |
| Overall Response (%) (95% CI) | 40 (56.3) (44.0, 68.1) |
| Complete Response | 19 (26.8%) |
| Very Good Partial Response | 6 (8.5%) |
| Partial Response | 15 (21.1%) |
The REACH2 study evaluated 309 patients with grade II to IV corticosteroid-refractory, acute GvHD were randomised 1:1 to Jakavi or BAT. Patients were stratified by severity of acute GvHD at the time of randomisation. Corticosteroid refractoriness was determined when patients had progression after at least 3 days, failed to achieve a response after 7 days or failed corticosteroid taper.
Jakavi was administered orally twice per day at a dose of 10 mg bid.
BAT was selected by the investigator on a patient-by-patient basis and included anti-thymocyte globulin (ATG), extracorporeal photopheresis (ECP), mesenchymal stromal cells (MSC), low dose methotrexate (MTX), mycophenolate mofetil (MMF), mTOR inhibitors (everolimus or sirolimus), etanercept, or infliximab.
In addition to Jakavi or BAT, patients could have received standard allogeneic stem cell transplantation supportive care including anti-infective medicinal products and transfusion support. as well as standard acute GvHD prophylaxis and treatment medicinal products initiated before randomisation including systemic corticosteroids and calcineurin inhibitors (CNIs) such as cyclosporine or tacrolimus. Topical or inhaled corticosteroid therapies were allowed to be continued per institutional guidelines.
Patients randomised to the BAT arm were allowed to cross over to the Jakavi arm after the day 28 visit, if they did not demonstrate complete or partial response at Day 28. Tapering of Jakavi was allowed after the day 56 visit for patients with treatment response.
The safety data derived from the REACH 2 study is presented above in section 4.8.
Chronic graft-versus-host disease
In REACH3, 329 patients with moderate or severe corticosteroid-refractory, chronic GVHD were randomised 1:1 to Jakavi or BAT. Patients were stratified by severity of chronic GVHD at the time of randomisation. Corticosteroid refractoriness was determined when patients had lack of response or disease progression after 7 days, or had disease persistence for 4 weeks or failed corticosteroid taper twice.
BAT was selected by the investigator on a patient-by-patient basis and included extracorporeal photopheresis (ECP), low dose methotrexate (MTX), mycophenolate mofetil (MMF), mTOR inhibitors (everolimus or sirolimus), infliximab, rituximab, pentostatin, imatinib, or ibrutinib.
Patients were allowed to have received allogeneic stem cell transplantation (SCT) from any donor source and with any conditioning regimen. In addition to Jakavi or BAT, patients could have received standard allogeneic SCT supportive care including anti-infective medicinal products and transfusion support. Continued use of corticosteroids and CNIs such as cyclosporine or tacrolimus and topical or inhaled corticosteroid therapies were allowed per institutional guidelines.
Patients who received one prior systemic treatment other than corticosteroids and CNIs for chronic GvHD were eligible for inclusion in the study. In addition to corticosteroids and CNIs, prior systemic medicinal product for chronic GvHD was allowed to continue only if used for chronic GvHD prophylaxis (i.e. started before the chronic GvHD diagnosis) as per common medical practice.
Patients on BAT not achieving partial response or better, could cross over to ruxolitinib on cycle 7 day 1 and thereafter.
Tapering of Jakavi was allowed after the cycle 7 day 1 visit.
Baseline demographics and disease characteristics were balanced between the two treatment arms. The median age was 49 years (range 12 to 76 years). The study included 3.6% adolescent, 61.1% male and 75.4% white patients. The majority of enrolled patients had malignant underlying disease.
The severity at diagnosis of corticosteroid-refractory chronic GVHD was balanced between the two treatment arms, with 41% and 45% moderate, and 59% and 55% severe, in the Jakavi and the BAT arms, respectively.
The reasons for patients' insufficient response to corticosteroids in the Jakavi and BAT arm were i) a lack of response or disease progression after corticosteroid treatment for at least 7 days at 1 mg/kg/day of prednisone equivalents (37.6% and 44.5%, respectively), ii) disease persistence after 4 weeks at 0.5 mg/kg/day (35.2% and 25.6%), or iii) corticosteroid dependency (27.3% and 29.9%, respectively).
Among all patients, 73% and 45% had skin and lung involvement in the Jakavi arm, compared to 69% and 41% in the BAT arm.
The most frequently used prior systemic chronic GVHD therapies were corticosteroids only (43% in the Jakavi arm and 49% in the BAT arm) and corticosteroids+CNIs (41% patients in the Jakavi arm and 42% in the BAT arm).
The primary endpoint was the ORR on day 1 of cycle 7, defined as the proportion of patients in each arm with a CR or a PR without the requirement of additional systemic therapies for an earlier progression, mixed response or non-response based on investigator assessment per National Institute of Health (NIH) criteria.
Key secondary endpoints were failure free survival (FFS) and proportion of patients with improvement of the modified Lee symptoms score (mLSS) at cycle 7 day 1. FFS, a composite time to event endpoint, incorporated the earliest of the following events: i) relapse or recurrence of underlying disease or death due to underlying disease, ii) non-relapse mortality, or iii) addition or initiation of another systemic therapy for chronic GVHD.
REACH3 met its primary objective. At the time of primary analysis (data cut-off data: 08-May-2020), the ORR at week 24 was higher in the Jakavi arm (49.7%) compared to the BAT arm (25.6%). There was a statistically significant difference between the treatment arms (stratified Cochrane-Mantel-Haenszel test p<0.0001, one-sided, OR: 2.99; 95% CI: 1.86, 4.80). Results are presented in Table 13.
Among the non-responders at cycle 7 day 1 in the Jakavi and BAT arms, 2.4% and 12.8% had disease progression, respectively.
Table 13 Overall response rate at cycle 7 day 1 in REACH3
| | Jakavi N=165 | BAT N=164 |
| | n (%) | 95% CI | n (%) | 95% CI |
| Overall response | 82 (49.7) | 41.8, 57.6 | 42 (25.6) | 19.1, 33.0 |
| OR (95% CI) | 2.99 (1.86, 4.80) |
| p-value | p<0.0001 |
| Complete response | 11 (6.7) | 5 (3.0) |
| Partial response | 71 (43.0) | 37 (22.6) |
The key secondary endpoint, FFS, demonstrated a statistically significant 63% risk reduction of Jakavi versus BAT (HR: 0.370; 95% CI: 0.268, 0.510, p<0.0001). Prior to crossover, the 5-months FFS probability (95% CI) was 78.1% (70.9%, 83.7%) and 62.7% (54.6%, 69.7%) for the Jakavi and BAT arms, respectively. The 6-months FFS probability (95% CI) was 74.9% (67.5%, 80.9%) and 44.5% (36.5%, 52.1%) for the Jakavi and BAT arms, respectively. At 6-months, the majority of FFS events were “addition or initiation of another systemic therapy for chronic GvHD” (probability of that event was 13.5% and 48.5% for the Jakavi and BAT arms, respectively). Results for “relapse of underlying disease” and non-relapse mortality (NRM) were 2.46% vs 2.57% and 9.19% vs 4.46%, in the Jakavi and the BAT arms, respectively. No difference of cumulative incidences between treatment arms was observed when focusing on NRM only.
The rate of responders as per improvement of ≥7 points of total symptom score (TSS) from baseline of the mLSS showed a statistically significant difference (p=0.0011) between the Jakavi (24.2%) and BAT arms (11.0%).
Paediatric population
The Medicines and Healthcare Products Regulatory Agency has waived the obligation to submit the results of studies with Jakavi in all subsets of the paediatric population for the treatment of MF and PV. In GvHD paediatric patients, the safety and efficacy of Jakavi are supported by evidence from the studies REACH1, REACH2 and REACH3 and from the open label single arm phase 2 studies REACH4 and REACH5 (see section 4.2 for information on paediatric use).
Acute graft versus host disease
In REACH4, 45 paediatric patients with grade II-IV acute GvHD were treated with Jakavi added to corticosteroids to assess the safety, efficacy and pharmacokinetics of Jakavi. Patients were enrolled into 4 groups based on age (Group 1 [age ≥12 years to <18 years, N=18], Group 2 [age ≥6 years to <12 years, N=12], Group 3 [age ≥2 years to <6 years N=15] and Group 4 [age ≥28 days to <2 years N=0]). The doses used in each group are listed in Table 12 and patients were treated for 24 weeks or until discontinuation. Jakavi was administered as either a 5 mg tablet or a capsule/oral solution for paediatric patients <12 years.
Patients were allowed to have received prior systemic treatment for acute GvHD or had treatment naive acute GvHD. In addition to Jakavi, patients could have received standard allogeneic stem cell transplantation supportive care including anti-infective medicinal products and transfusion support. Continued use of systemic corticosteroids, CNI (cyclosporine or tacrolimus) and/or topical corticosteroid therapies were allowed per institutional guidelines.
Tapering of Jakavi was allowed after the day 56 visit.
Male and female patients accounted for 62.2% (n=28) and for 37.8% (n=17) patients, respectively. Overall, 27 patients (60.0%) had underlying malignancy, most frequently leukaemia (26 patients, 57.8%). Among the 45 paediatric patients enrolled in REACH4, 13 (28.9%) had treatment naïve acute GvHD and 32 (71.1%) had steroid refractory (SR)-acute GvHD. At baseline 64.4% of patients had grade II, 26.7% had grade III and 8.9% had grade IV aGvHD.
The overall response rate (ORR) at day 28 (primary efficacy endpoint) in REACH4 was 84.4% (90% CI: 72.8, 92.5) in all patients with CR in 48.9% of patients and PR in 35.6% of patients. In terms of pre-treatment status, the ORR at day 28 was 90.6% in SR-patients and 69.2% in treatment-naïve patients.
Rate of durable ORR at day 56 (measured by the proportion of patients who achieve a CR or PR at day 28 and maintain a CR or PR at day 56) was 66.7% in all REACH4 patients, 68.8% in SR-patients and 61.5% in treatment-naïve patients.
In REACH2, responses were observed at day 28 in 4 out of 5 adolescent patients with acute GvHD (3 had CR and 1 had PR) in the ruxolitinib arm and in 3 out of 4 adolescent patients (all had CR) in the BAT arm.
Overall response rate from all ruxolitinib paediatric patients (adolescents from REACH2 and paediatric patients from REACH4) are presented in Table 14.
Table 14 Overall response rate (ORR) at day 28 in acute GvHD paediatric patients
| | REACH4 | REACH2 | REACH4 and 2 |
| | ≥12 years to <18 years (Jakavi 10 mg twice daily) n (%) | ≥6 years to <12 years (Jakavi 5 mg twice daily) n (%) | ≥2 years to <6 years (Jakavi 4 mg/m2 twice daily) n (%) | All patients n (%) | ≥12 years to <18 years (Jakavi 10 mg twice daily) n (%) | Total paediatric patients n (%) |
| | N=18 | N=12 | N=15 | N=45 | N=5 | N=50 |
| ORR at day 28 | 15 (83.3) | 10 (83.3) | 13 (86.7) | 38 (84.4) | 4 (80.0) | 42 (84.0) |
| 90% CI for ORR | (62.3, 95.3) | (56.2, 97.0) | (63.7, 97.6) | (72.8, 92.5) | (34.3, 99.0) | (73.0, 91.8) |
| Complete response | 8 (44.4) | 4 (33.3) | 10 (66.7) | 22 (48.9) | 3 (60.0) | 25 (50.0) |
| Partial response | 7 (38.9) | 6 (50.0) | 3 (20.0) | 16 (35.6) | 1 (20.0) | 17 (34.0) |
Chronic graft versus host disease
In REACH5, 45 paediatric patients with moderate or severe chronic GvHD were treated with Jakavi added to corticosteroids to assess safety, efficacy and pharmacokinetics of Jakavi treatment. Patients were enrolled into 4 groups based on age (Group 1 [age ≥12 years to <18 years, N=22], Group 2 [age ≥6 years to <12 years, N=16], Group 3 [age ≥2 years to <6 years, N=7] and Group 4 [age ≥28 days to <2 years, N=0]). The doses used in each group are listed in Table 13 and patients were treated for 39 cycles/156 weeks or until discontinuation. Jakavi was administered as either a 5 mg tablet or an oral solution for paediatric patients <12 years.
Patients were allowed to have received prior systemic therapy for chronic GvHD or had treatment-naive chronic GvHD. In addition to Jakavi, patients could have received standard allogeneic stem cell transplantation supportive care including anti-infective medicinal products and transfusion support. Continued use of topical corticosteroid therapies were allowed per institutional guidelines
Tapering of Jakavi was allowed after the cycle 7 day 1 visit.
Male and female patients accounted for 64.4% (n=29) and for 35.6% (n=16) of patients, respectively. with 30 patients (66.7%) with pre-transplant disease history of underlying malignancy, most frequently leukaemia (27 patients, 60%).
Among the 45 paediatric patients enrolled in REACH5, 17 (37.8%) were treatment-naïve chronic GvHD patients and 28 (62.2%) were SR-chronic GvHD patients. The disease was severe in 62.2% of patients and moderate in 37.8% of patients. Thirty-one (68.9%) patients had skin involvement, eighteen (40%) had mouth involvement, and fourteen (31.1%) had lung involvement.
The ORR at cycle 7 day 1 (primary efficacy endpoint) was 40% (90% CI: 27.7, 53.3) in REACH5 paediatric patients, 39.3% in SR-patients and 41.2% in treatment-naïve patients.
The best overall response (BOR) defined as the proportion of patients who achieved overall response (CR or PR) at any time up to cycle 7 day 1 or up to the start of additional systemic therapy for chronic GvHD was 82.2% (90% CI: 70.2, 90.8) in REACH5 paediatric patients.
In REACH3, responses were observed at cycle 7 day 1 in 3 out of 4 adolescent patients with chronic GvHD (all had PR) in the ruxolitinib arm and in 2 out of 8 adolescent patients (both had PR) in the BAT arm.
Overall response rate from all ruxolitinib paediatric patients (adolescent from REACH3 and paediatric patients from REACH5) are presented in Table 15.
Table 15 Overall response rate (ORR) at cycle 7 day 1 in chronic GvHD paediatric patients
| | REACH 5 | REACH 3 | REACH 5 and 3 |
| | ≥12 years to <18 years (Jakavi 10 mg twice daily) n (%) | ≥6 years to <12 years (Jakavi 5 mg twice daily) n (%) | ≥2 years to <6 years (Jakavi 4 mg/m2 twice daily) n (%) | All patients n (%) | ≥12 years to <18 years (Jakavi 10 mg twice daily) n (%) | Total paediatric patients n (%) |
| | N= 22 | N=16 | N=7 | N=45 | N=4 | N=49 |
| ORR at cycle 7 day 1 | 8 (36.4) | 8 (50.0) | 2 (28.6) | 18 (40.0) | 3 (75.0) | 21 (42.9) |
| ORR at cycle 7 day 1 (90% CI) | (19.6, 56.1) | (27.9, 72.1) | (5.3, 65.9) | (27.7, 53.3) | (24.9, 98.7) | (30.8, 55.6) |
| Complete response | 1 (4.5) | 2 (12.5) | 1 (14.3) | 4 (8.9) | 0 | 4 (8.2) |
| Partial response | 7 (31.8) | 6 (37.5) | 1 (14.3) | 14 (31.1) | 3 (75.0) | 17 (34.7) |