Anemia-related response end points in myelofibrosis clinical trials: current trends and need for renewed consensus

JAK inhibitors are the current standard of care in myelofibrosis, but many do not address and may worsen anemia; thus, anemia-related responses have traditionally been overlooked as efficacy end points in pivotal clinical trials, leading to a lack of consistency and analytic detail in their reporting. Here we apply our experiences in the phase III trials of momelotinib, a JAK1/JAK2/ACVR1 inhibitor and the first therapy indicated by the US FDA for myelofibrosis patients with anemia, to highlight how application of different criteria impacts the anemia-related benefits reported for any potential treatment in myelofibrosis. We advocate for a convention of a new expert consensus panel to bring consistency and transparency to the definition of anemia-related response in myelofibrosis.

Momelotinib vs. ruxolitinib in myelofibrosis patient subgroups by baseline hemoglobin levels in the SIMPLIFY-1 trial

A key hallmark of myelofibrosis is anemia, which ranges from mild to severe based on hemoglobin levels. To more clearly define outcomes with the Janus kinase (JAK) 1/JAK2/activin A receptor type 1 inhibitor momelotinib by anemia severity, we performed a descriptive post hoc exploratory analysis of the double-blind, randomized, phase 3 SIMPLIFY-1 study (NCT01969838; N = 432, JAK inhibitor naive, momelotinib vs. ruxolitinib); subgroups were defined by baseline hemoglobin: <10 (moderate/severe), ≥10 to <12 (mild), or ≥12 g/dL (nonanemic). Spleen and symptom results were generally consistent with those previously reported for the intent-to-treat population. In anemic subgroups, momelotinib was associated with higher rates of transfusion independence and reduced/stable transfusion intensity vs. ruxolitinib. No new or unexpected safety signals were identified. Overall, momelotinib provides spleen, symptom, and anemia benefits to JAK inhibitor-naive patients with myelofibrosis regardless of baseline hemoglobin level, and greater anemia-related benefits vs. ruxolitinib in patients with hemoglobin <12 g/dL.

Transfusion Burden in Allogeneic Hematopoietic Stem Cell Transplantation over Time: Experience from a Single Institution

INTRODUCTION

Transfusion plays a main role in supportive treatment for patients who receive an allogeneic hematopoietic stem cell transplantation (HSCT). In this study, we compare the transfusion requirements of patients undergoing different modalities of HSCT according to different time periods. The objective is to assess the evolution of HSCT transfusion requirements over time, from a single institution.

METHODS

The clinical charts and transfusion records of patients who underwent HSCT of different modalities at La Fe University Hospital during a twelve-year period were reviewed (2009-2020). For analysis, we divided the overall time into three periods: 1 from 2009 to 2012, 2 from 2013 to 2016 and 3 from 2017 to 2020. The study included 855 consecutive adult HSCT: 358 HLA-matched related donors (MRD), 134 HLA-matched unrelated donors (MUD), 223 umbilical cord blood transplantation (UCBT) and 140 haploidentical transplants (Haplo-HSCT).

RESULTS

There were no significant differences in RBC and PLT requirements or transfusion independence among the three time periods for MUD and Haplo-HSCT. However, the transfusion burden increased significantly for MRD HSCT during the 2017-2020 period.

CONCLUSION

despite HSCT modalities having evolved and changed over time, overall transfusion requirements have not significantly decreased and continue to be a cornerstone of transplantation-supportive care.

MPN-145 Retrospective Analysis of Anemia Benefit of Pacritinib From the PERSIST-2 Trial

BACKGROUND

Pacritinib (PAC) is a novel JAK2/IRAK1 inhibitor approved for patients with myelofibrosis (MF) and platelets <50×10^9/L. Previous publications have characterized PAC's unique advantage of reduced myelosuppression. We conducted a retrospective analysis of the phase 3 PERSIST-2 trial to assess PAC's impact on anemia and performed in vitro analysis to explore PAC inhibition of ACVR1 (ALK2).

METHODS

This analysis included PERSIST-2 patients with platelet count ≤100×10⁹/L randomized to PAC 200mg BID, PAC 400mg QD, or best available therapy BAT. Transfusion independence (TI) was defined as no RBC transfusions and no hemoglobin level <8g/dL. PAC's activity against ACVR1 was assessed using the HotSpot assay from Reaction Biology Corporation. The activity of the JAK1/JAK2/ACVR1 inhibitor momelotinib was also assessed. IC50 was calculated using 3-fold serial dilutions starting at 10µM.

RESULTS

The analysis included 106 patients on PAC 200mg BID, 104 on 400mg QD and 98 on BAT. Patients at baseline, were severely cytopenic, with a median platelet count of 55×10⁹/L. Among patients with baseline hemoglobin <10g/dL, the percentage who achieved ≥1g/dL improvement at any time through week 24 was higher on PAC than BAT (PAC 200mg BID: 15% (5/33); PAC 400mg QD: 23% (7/30); BAT: 7% (2/28). The percentage who achieved an increase of ≥2g/dL trended similarly: PAC 200mg BID: 9% (3/33), PAC 400mg QD: 7% (2/30), BAT: 4% (1/28)). Among patients receiving transfusions or with Hb <8 at baseline, the percentage who achieved TI at any point (evaluated at 12-week intervals) through week 24 was greater on PAC 200mg BID (7/26, 27%) and PAC 400mg QD (6/24, 25%) than BAT (1/19, 5%). On duplicate assays, pacritinib was shown to inhibit ACVR1 with an IC₅₀ of 23 and 11nM. Momelotinib's IC₅₀ was 70 and 35nM in the same assay.

CONCLUSIONS

Improvement in hemoglobin levels and transfusion requirements was greater on PAC than BAT, in PERSIST-2. This anemia benefit could be due to PAC's ability to inhibit the iron regulator ACVR1, which has been linked to hepcidin reduction and anemia benefit. These data suggest an important role for PAC in anemic patients with myelofibrosis. This study was supported by CTI BioPharma.

Transfusion burden following reduced intensity allogeneic hematopoietic cell transplantation: Impact of donor type

BACKGROUND

Transfusions are essential for allogeneic hematopoietic cell transplant (HCT), yet they are influenced by graft, donor, and other factors.

STUDY DESIGN

We analyzed transfusions in 165 adult reduced intensity HCTs (2016-2019): HLA matched sibling donor (MSD) (n = 59), matched URD (n = 25), UCB (n = 33), and haploidentical (haplo, n = 48) detailing the cumulative incidence of platelet and RBC transfusion independence, total transfusions (day-10 to day+100) plus transfusion densities (per week) over 110 days.

RESULTS

Platelet recovery to 20 × 10⁹ /L by 6 months occurred in 39/48 (81.25%) haplo recipients (median 33 [range, 0-139]) days vs. 58/59 (98.3%) MSD (median 10 [0-37]), 21/25 (84%) matched URD (median 20 [0-153]), and 29/33 (87.87%) UCB (median 48 [29-166]) days, p < .01. Regression analysis demonstrated a lower likelihood of prompt platelet recovery in matched URD, UCB, or haplo HCTs vs. MSD. Recovery to platelet independence was quickest in MSD (median 8 days [range 0-94]), vs. URD (median 16 days [0-99]), UCB (median 57 [0-94]), or haplo (median 45 [12-97]) days, p < .01. Platelet needs were unaffected by age, conditioning, or acute GVHD. RBC transfusion independence was achieved in 78% of MSD, 64% URD, and 82% UCB, though less frequent (58%) and slowest in haplo recipients, p < .01. All haplo and UCB recipients required platelet transfusions vs. only 51% of MSD and 76% of URD. RBC needs were highest in UCB and haplo HCTs.

DISCUSSION

The transplant donor influences the transfusion burden with greater platelet and RBC needs in haplo and UCB HCT which directly contributes to increased cost of care.

Lenalidomide in patients with red blood cell transfusion-dependent myelodysplastic syndrome and del(5q): a single-centre "real-world" experience

"Real life" data are needed to complement published trials on the efficacy of lenalidomide in patients with myelodysplastic syndrome (MDS) and del(5q) and on the risk of inducing acute myeloid leukemia (AML) progression. Here, we present results of lenalidomide treatment in a consecutive, population-based series of 21 red blood cell (RBC) transfusion-dependent elderly patients with multiple comorbidities. Of 18 evaluable patients (median follow-up: 22 months), 17 achieved an erythroid hematologic response (HI-E) and 16 an RBC transfusion independence. Cytogenetic response (CyR) rate was 80%, median overall survival was 48 months (range 3-164), and 5-year leukemia-free survival was 84%. Three patients progressed to AML; one, with baseline TP53 mutation, achieved HI-E, partial CyR, and did not progress to AML. Eighteen patients experienced hematological adverse events. Overall, lenalidomide was very effective and well tolerated even in unselected elderly patients with multiple comorbidities and did not appear to increase the risk of AML.

Outcomes in RBC transfusion-dependent patients with Low-/Intermediate-1-risk myelodysplastic syndromes with isolated deletion 5q treated with lenalidomide: a subset analysis from the MDS-004 study

Objective

A subset analysis of the randomised, phase 3, MDS-004 study to evaluate outcomes in patients with International Prognostic Scoring System (IPSS)-defined Low-/Intermediate (Int)-1-risk myelodysplastic syndromes (MDS) with isolated del(5q).

Methods

Patients received lenalidomide 10 mg/d (days 1–21; n = 47) or 5 mg/d (days 1–28; n = 43) on 28-d cycles or placebo (n = 45). From the placebo and lenalidomide 5 mg groups, 84% and 58% of patients, respectively, crossed over to lenalidomide 5 or 10 mg at 16 wk, respectively.

Results

Rates of red blood cell-transfusion independence (RBC-TI) ≥182 d were higher in the lenalidomide 10 mg (57.4%; P < 0.0001) and 5 mg (37.2%; P = 0.0001) groups vs. placebo (2.2%). Cytogenetic response rates (major + minor responses) were 56.8% (P < 0.0001), 23.1% (P = 0.0299) and 0%, respectively. Two-year cumulative risk of acute myeloid leukaemia progression was 12.6%, 17.4% and 16.7% in the lenalidomide 10 mg, 5 mg, and placebo groups, respectively. In a 6-month landmark analysis, overall survival was longer in lenalidomide-treated patients with RBC-TI ≥182 d vs. non-responders (P = 0.0072). The most common grade 3–4 adverse event was myelosuppression.

Conclusions

These data support the clinical benefits and acceptable safety profile of lenalidomide in transfusion-dependent patients with IPSS-defined Low-/Int-1-risk MDS with isolated del(5q).

Extended survival and reduced risk of AML progression in erythroid-responsive lenalidomide-treated patients with lower-risk del(5q) MDS

Lenalidomide is the approved treatment for patients with red blood cell (RBC) transfusion-dependent lower-risk myelodysplastic syndromes (MDS) and chromosome 5q deletion (del(5q)). We report the long-term outcomes (median follow-up 3.2 years) in patients treated with lenalidomide in the MDS-003 trial. RBC transfusion independence (TI) ≥ 8 weeks was achieved in 97 of 148 treated patients (65.5%), with a median response duration of 2.2 years. Partial or complete cytogenetic response was achieved by 63 of 88 evaluable patients (71.6%). Median overall survival (OS) was longer in patients achieving RBC-TI ≥ 8 weeks (4.3 vs 2.0 years in non-responders; P<0.0001) or cytogenetic response (4.9 vs 3.1 years in non-responders; P=0.010). Time to acute myeloid leukemia (AML) progression was longer in patients achieving RBC-TI ≥ 8 weeks or any cytogenetic response versus non-responders (P=0.001 and P=0.0002, respectively). In a landmark multivariate analysis, RBC-TI ≥ 8 weeks was associated with prolonged OS (P<0.001) and a trend toward reduced relative risk of AML progression (P=0.080). Among these lower-risk MDS patients with del(5q), lenalidomide was associated with prolonged RBC-TI and cytogenetic responses, which were linked to improved OS and reduced risk of AML progression.