PURPOSE
Patients with myelofibrosis who are relapsed or refractory (R/R) to Janus-associated kinase inhibitors (JAKis) have poor clinical outcomes including dismal overall survival (OS) that ranges ...between 13 and 16 months. Imetelstat, a telomerase inhibitor, was evaluated in patients with intermediate-2 or high-risk myelofibrosis R/R to JAKi in a phase II multicenter study (ClinicalTrials.gov identifier: NCT02426086 ).
PATIENTS AND METHODS
Patients were randomly assigned to receive either imetelstat 9.4 mg/kg or 4.7 mg/kg intravenous once every 3 weeks. Spleen response (≥ 35% spleen volume reduction) and symptom response (≥ 50% reduction in total symptom score) rates at week 24 were coprimary end points. Secondary end points included OS and safety.
RESULTS
Study enrollment was closed early, and patients treated with 4.7 mg/kg were permitted to continue treatment with 9.4 mg/kg. At week 24, spleen and symptom response rates were 10.2% and 32.2% in the 9.4-mg/kg arm and 0% and 6.3% in the 4.7-mg/kg arm. Treatment with imetelstat 9.4 mg/kg led to a median OS of 29.9 months and bone marrow fibrosis improvement in 40.5% and variant allele frequency reduction of driver mutations in 42.1% of evaluable patients. Fibrosis improvement and variant allele frequency reduction correlated with OS. Target inhibition was demonstrated by reduction of telomerase activity and human telomerase reverse transcriptase level and correlated with spleen response, symptom response, and OS. Most common adverse events on both arms were grade 3 or 4 reversible cytopenias.
CONCLUSION
In this phase II study of two imetelstat doses, 9.4 mg/kg once every 3 weeks demonstrated clinical benefits in symptom response rate, with an acceptable safety profile for this poor-risk JAKi R/R population. Biomarker and bone marrow fibrosis assessments suggested selective effects on the malignant clone. A confirmatory phase III study is currently underway.
CONCLUSIONS Imetelstat, a first-in-class telomerase inhibitor, showed higher rates of red blood cell (RBC) transfusion independence (TI) for ≥8 weeks, ≥24 weeks, and ≥1 year (39.8%, 28.0%, and 17.8%) ...than placebo (15.0%, 3.3%, and 1.7%) in the IMerge (NCT02598661) phase 3 study of patients with RBC transfusion-dependent non-del(5q) lower-risk myelodysplastic syndromes (LR-MDS) relapsed/refractory to erythropoiesis-stimulating agents (Platzbecker et al. EHA 2023. Abstr S165). To evaluate the impact of MDS-associated mutations on clinical efficacy of imetelstat, we performed next-generation sequencing of a panel of 36 genes, recurrently mutated in MDS, using DNA samples from peripheral blood collected at study entry. Further analysis of TI responses to imetelstat was performed across different mutation subgroups, defined based on genes involved in different biological functions, including the splicing process, epigenetic modifiers, transcription regulation, and receptors/kinases. Baseline mutation data were available in 165 of 178 patients (imetelstat, n = 110; placebo, n = 55; 93.2% and 91.7% of total in each group, respectively). Of patients with mutation data, 161 (97.6%) had ≥1 mutation detected, among whom, 75 (70.1%), 33 (30.8%), and 9 (8.4%) patients in the imetelstat group and 38 (70.4%), 15 (27.8%), and 7 (13%) patients in the placebo group had >1, >2, and >3 mutations, respectively. The ≥8-week TI rates in the imetelstat vs placebo groups were 42.7% vs 15.8% ( P = .006) for patients with >1 mutation, 45.5% vs 6.7% ( P = .012) for patients with >2 mutations, and 55.6% vs 14.3% ( P = .089) for patients with >3 mutations, respectively. The ≥24-week TI rates were 26.7% vs 2.6% ( P = .003), 33.3% vs 0% ( P = .014), and 33.3% vs 0% ( P = .117), respectively. In patients with mutations associated with poor prognosis ( TP53, ETV6, RUNX1, ASXL1 or EZH2), 31.8% and 9.1% of patients in the imetelstat group achieved ≥8-week and ≥24-week TI vs 0 of those in the placebo group. TP53 mutations were detected in 2 patients in each group; both patients in the imetelstat group and none in the placebo group had ≥8-week TI. Among patients with ASXL1 mutations, 5 of 18 patients (27.8%) in the imetelstat and 0 of 6 (0) in placebo group had ≥8-week TI. Among patients with ETV6 mutations, 1 of 2 (50%) in the imetelstat group and 0 of 1 patients in the placebo group had ≥8-week TI. Two patients in each group had RUNX1 mutations; none achieved TI. Imetelstat ≥8-week TI rates were 43.8%, 37.7%, 40.0%, and 80.0% for patients harboring mutated genes in the RNA spliceosome, epigenetic modifiers, transcription regulation, and receptors/kinases, respectively; ≥24-week TI was 30.2%, 27.5%, 20.0%, and 80.0%, respectively. The most frequently mutated gene was SF3B1 (125 of 165; 75.8%), the ≥8-week and ≥24-week TI rates were 48.8% vs 16.3% ( P = .001) and 35.4% vs 2.3% ( P < .001) with imetelstat vs placebo. In the imetelstat group, ≥8-week TI was achieved in patients with different spectrum of SF3B1 hot-spot mutations: 2 of 8 patients (25.0%) with E622D, 4 of 7 (57.1%) with R625C/L/G, 7 of 12 (58.3%) with H662Q/N/D/Y, 2 of 2 (100%) with T663P, 2 of 6 (33.3%) with K666R/T/Q/N, 18 of 41 (43.9%) with K700E, 2 of 2 (100%) with A744P, and 1 of 2 patients (50.0%) with E783K. Durable ≥24-week TI was also observed in patients with these hot-spot mutations. Other genes with mutation frequency >10% were TET2 (32.7%), DNMT3A (17.0%), ASXL1 (14.5%), and CUX1 (12.7%). The ≥8-week TI rates in the imetelstat group vs placebo group were 50% vs 21.4% for TET2 mutations; 31.6% vs 22.2% for DNMT3A mutations; 27.8% vs 0 for ASXL1 mutations; 35.7% vs 14.3% for CUX1 mutations (Figure). The ≥24-week TI rates were 40% vs 0, 26.3% vs 11.1%, 11.1% vs 0, and 14.3% vs 0, respectively, for those mutations (Figure). Higher RBC-TI rates were observed in patients with various baseline mutational profiles treated with imetelstat compared with placebo in IMerge. While the sample size for specific mutations was small, consistent with the observation that patients with LR-MDS have a low number of specific mutations, TI responses in patients receiving imetelstat occurred regardless of the presence of mutations associated with poor prognosis or the number of mutations. Imetelstat showed comparable TI rates across different molecularly defined subgroups, suggesting that clinical benefit of imetelstat in patients with LR-MDS is independent of the underlying molecular pattern.
CONCLUSIONS Imetelstat, an oligonucleotide and a first-in-class telomerase inhibitor, selectively targets malignant hematopoietic stem and progenitor cells with high telomerase activity by direct ...binding to the RNA template. In patients with MDS the on-target effects of imetelstat are associated with the development of hematologic treatment-emergent adverse events (TEAEs). In the IMerge phase 3 trial, among patients treated with imetelstat, 68% experienced grade 3-4 neutropenia, and 62% had grade 3-4 thrombocytopenia; however, clinical consequences of grade 3-4 infection or bleeding were similar in patients treated with imetelstat and placebo (Platzbecker et al. EHA 2023. Abstr S165). Here, we report additional data on the occurrence and management of cytopenias after treatment with imetelstat. IMerge phase 3 trial (NCT02598661) is a multicenter study involving 178 patients with a median age of 72 years with red blood cell (RBC) transfusion dependency and LR-MDS relapsed/refractory to or ineligible for erythropoiesis-stimulating agents. Patients were randomized 2:1 to receive either imetelstat or placebo and stratified by prior RBC transfusion burden (4-6 or >6 U) and by International Prognostic Scoring System risk group. The safety population included all patients who received ≥1 dose of study drug and comprised 118 patients treated with imetelstat and 59 with placebo. TEAEs of neutropenia and thrombocytopenia with imetelstat treatment were more prevalent in cycles 1-3 (68.6% and 62.7% respectively), and their frequency decreased over time: 42.7% and 48.5% in cycles 4-6, 36.8% and 44.7% in cycles 7-12, and 31.3% and 37.5% in cycle 13 and beyond. Based on laboratory assessment, neutrophil and platelet counts decreased from baseline levels in patients treated with imetelstat versus those treated with placebo (91.5% and 95.8% vs 47.5% and 33.9%, respectively). Neutropenia decreased to a maximum of grade 4 and 3 in 55 and 29 of imetelstat-treated patients, respectively, and >80% of cytopenia events stabilized to grade ≤2 within 4 weeks (Figure). The median time to grade 4 neutropenia was 5.0 weeks (range,1.1-90.3 weeks) for the imetelstat group vs 23.0 weeks (range, 23.0-23.0 weeks) for the placebo group. Similarly, median time to grade 4 thrombocytopenia was 5.2 weeks (range, 2.0-29.9 weeks) with imetelstat vs 35.5 weeks (range, 28.0-43.0 weeks) with placebo. It is noteworthy that among 47 patients who achieved the primary end point of 8-week RBC transfusion independence with imetelstat, 34 (72.3%) and 28 patients (59.6%) had grade 3-4 neutropenia and grade 3-4 thrombocytopenia, respectively. In the imetelstat group, 3 patients had grade 3-4 neutropenia concurrent with grade 3-4 infections, and no patients experienced grade 3-4 thrombocytopenia associated with grade 3-4 bleeding events. There were no grade 5 cytopenias for either imetelstat or placebo groups. In the imetelstat group, cytopenias were managed with protocol-specified treatment delays and dose adjustments. Dose reductions due to neutropenia and thrombocytopenia occurred in 39 patients (33.1%) and 27 patients (22.9%), respectively. Of imetelstat-treated patients, 6 (5.1%) discontinued treatment due to neutropenia (1 case, grade 4; all others, grade 3), and 4 (3.4%) discontinued due to thrombocytopenia (1 case, grade 2; 3 cases, grade 3). In addition to dose reductions and discontinuation of imetelstat, thrombocytopenia and neutropenia were managed by cycle delays in 46.6% and 50.8% of patients, by platelet transfusions in 17.8% of patients, and by concomitant therapy with growth factor support (mostly during cycles 2-4) in 34.7% of patients. Similar patterns of imetelstat dose modifications were seen in a pooled phase 2 and phase 3 safety analysis of IMerge. In the IMerge phase 3 trial, thrombocytopenia and neutropenia were the most common and most frequently reported grade 3-4 AEs during treatment cycles 1-3. However, these AEs were generally transient, reversible, and manageable through treatment delays and dose adjustments, allowing for patients to remain on treatment and continue to experience clinical benefit. Moreover, occurrence of grade 3-4 cytopenias in responders suggests that these TEAEs do not affect the efficacy of imetelstat.
CONCLUSIONS IMerge (NCT02598661) is a phase 2/3 global study of imetelstat, a first-in-class telomerase inhibitor, for patients with RBC transfusion-dependent non-del(5q) LR-MDS R/R to or ineligible ...for ESAs, a population with unmet needs. Phase 3 results showed that the rate of ≥8-week, ≥24-week and 1-year RBC-TI was higher with imetelstat than placebo (Zeidan et al. ASCO 2023. Abstr 7004; Platzbecker et al. EHA 2023. Abstr S165). Toevaluate clinical efficacy of imetelstat across different International Prognostic Scoring System (IPSS), revised IPSS (IPSS-R), IPSS-R cytogenetic, or IPSS-molecular (IPSS-M) risk categories,cytogenetic analysis was performed centrally on bone marrow aspirates by karyotyping, and mutation profile was analyzed using peripheral blood samples by next-generation sequencing on a panel of 36 genes commonly mutated in MDS. Baseline IPSS, IPSS-R, IPSS-R cytogenetic, or IPSS-M risk categories were derived for patients in the phase 3 portion of IMerge based on specific classification criteria, and rates of RBC-TI ≥8-week, ≥24-week, ≥1-year were assessed for each risk subgroup. In 105 IPSS-low patients, 95 (90.5%) remained IPSS-M very low/low/moderate low, and 10 patients (9.5%) upstaged to IPSS-M moderate high and high. In 50 IPSS-intermediate-1 patients, 39 (78%) remained IPSS-M very low/low/moderate low, and 11 patients (22%) upstaged to IPSS-M moderate high/high. Among 129 IPSS-R low/very low patients, 118 (91.5%) remained IPSS-M very low/low/moderate low, and 11 (8.5%) patients upstaged to IPSS-moderate high/high. In 25 IPSS-R-intermediate patients, 16 (64%) remained IPSS-M low/moderate low, and 9 patients (36%) upstaged to IPSS-M moderate high/high/very high. One IPSS-R high-risk patient remained IPSS-M high. Overall, significantly higher rates of ≥8-week, ≥24-week, and ≥1-year RBC-TI were achieved in patients receiving imetelstat (39.8%, 28%, and 13.6%) vs those receiving placebo (15%, 3.3%, and 1.7%). Further subgroup analysis demonstrated that imetelstat consistently had higher TI response rates than placebo across different risk subgroups, irrespective of classification system. For IPSS risk groups, the TI rates of ≥8-week, ≥24-week, and ≥1-year with imetelstat vs placebo were 40.0% vs 20.5% ( P = 0.034), 28.8% vs 5.1% ( P = 0.003), and 12.5% vs 2.6% ( P = 0.082), respectively, in patients with low risk and 39.5% vs 4.8% ( P = 0.004), 26.3% vs 0% ( P = 0.009), and 15.8% vs 0% ( P = 0.048), respectively, in patients with intermediate-1 risk. For IPSS-R risk groups, the TI rates of ≥8-week, ≥24-week, and ≥1-year with imetelstat vs placebo were 42.5% vs 19.6%, 29.9% vs 4.3%, and 11.5% vs 2.2%, respectively, in the low-risk subgroup. The TI rates of ≥8-week, ≥24-week, ≥1-year TI with imetelstat were 35%, 25%, and 20%, respectively, in the intermediate-risk subgroup, whereas placebo treatment had no response. The number of patients was too low in both arms of the very low or high IPSS-R subgroups to assess difference in TI response. For IPSS-R cytogenetic risk groups, the TI rates of ≥8-week, ≥24-week, and ≥1-year with imetelstat vs placebo were 37.1% vs 17.0%, 24.7% vs 4.3%, and 10.1% vs 2.1%, respectively, in very good/good risk groups and 54.5% vs 11.1%, 40.9% vs 0%, and 22.7% vs 0%, respectively, in the intermediate-risk group. For IPSS-M risk groups, the TI rates of ≥8-week, ≥24-week, and ≥1-year with imetelstat vs placebo were 47.8% vs 21.2%, 34.8% vs 3%, and 14.5% vs 0%, respectively, in patients with very low/low risk and 20.7% vs 6.3%, 10.3% vs 0%, and 6.9% vs 0%, respectively, in patients with moderate low/moderate high risk. In patients with high/very high risk, ≥8-week TI rates were 40% vs 0% with imetelstat vs placebo, with no ≥24-week or ≥1-year TI observed in either arm. All results are summarized in the Table. Improvement in RBC-TI rates was observed in patients treated with imetelstat vs placebo across different risk subgroups as defined by IPSS, IPSS-R, IPSS-R cytogenetic, or IPSS-M risk profiles. Notably, placebo had not achieved durable (≥24-week and ≥1-year) TI response in the higher-risk groups irrespective of the risk classification assessment model used, while TI response rates with imetelstat in higher-risk subgroups with poor prognosis were similar to TI response rates in lower-risk subgroups of heavily transfused R/R ESA LR-MDS, indicating that clinical efficacy of imetelstat is independent of risk categories.
CONCLUSIONS MDS are serious life-threatening hematologic malignancies in which a heterogeneous group of clonal disorders results in ineffective hematopoiesis. An unmet need remains for new therapies ...for patients (pts) with LR-MDS who are red blood cell transfusion dependent (RBC-TD) and R/R to or ineligible for ESAs. Imetelstat, an oligonucleotide, is a first-in-class telomerase inhibitor that targets cells with high telomerase activity by direct binding to the RNA template of telomerase. In the IMerge phase 3 trial, imetelstat produced higher rates of TI for ≥8 weeks, ≥24 weeks, and ≥1 year (39.8%, 28.0%, and 17.8%) than placebo (15.0%, 3.3%, and 1.7%) in pts with non-del(5q) LR-MDS that was RBC-TD, R/R to/ineligible for ESAs, and naïve to lenalidomide or hypomethylating agents (HMAs; Platzbecker et al. EHA 2023. Abstr S165). We report characteristics and clinical benefit for pts with sustained TI for ≥1 year from this trial. IMerge (MDS3001, NCT02598661) is a global, double-blind, randomized, placebo-controlled, phase 3 trial of imetelstat in RBC-TD, ESA-R/R, non-del 5(q) lenalidomide/HMA-naïve LR-MDS. The primary end point was 8-week TI rate; secondary end points included safety, 24-week TI, duration of response, hematologic improvement, and MDS response. Exploratory end points included assessment of cytogenetic response and mutational status with clinical response. The proportion of pts with>1-year TI and other binary end points, were summarized with percentage and 95% 2-sided exact Clopper-Pearson CI. The Kaplan-Meier method was used to estimate the distribution of TI. Of 118 pts receiving imetelstat, 21 (17.8%; 95% CI, 11.4-25.9) achieved ≥1-year sustained TI, representing 45% of ≥8-week TI (21 of 47 pts) and 64% of ≥24-week TI (21 of 33 pts); of 60 pts receiving placebo plus supportive care, 1 (1.7%; 95% CI, 0-8.9) achieved ≥1-year TI. Of the ≥1-year TI imetelstat responders, 15/21 (71.4%) had ring sideroblasts, as did the 1 placebo pt. The median prior RBC transfusion burden was 6 U over 8 weeks (range, 4-9 U) for the imetelstat group and 5 U for the placebo pt. Additional baseline characteristics are in the table. Pts received imetelstat for a median of 101.1 weeks (range, 75.1-163.9 weeks) and a median of 24 cycles (range, 18-41 cycles). The median duration of TI for imetelstat ≥1-year TI responders was 123 weeks (95% CI, 80.4 to not evaluable); the median increase in hemoglobin during the longest TI interval was 5.18 g/dL (range, 2.67-13.76 g/dL) for the imetelstat group vs 1.67 g/dL for the placebo pt. After a median follow-up of 125 weeks, none of the patients with ≥1 year TI on either arm progressed to acute myeloid leukemia (AML). Of the pts receiving imetelstat, 7 had an abnormal karyotype at baseline, of which 6 had reduction in the cytogenetic abnormal clones (4 with cytogenetic complete response and 2 with cytogenetic partial response by independent review committee). Mutation data were available for 18 pts receiving imetelstat, all with SF3B1 mutations present at baseline, and multiple of these pts concurrently had TET2, DNMT3A, ASXL1, or JAK2 mutations. The maximal reduction ranged from −6% to −100% in SF3B1 variant allele frequency (VAF) in these pts, and 13 of 18 (72.2%) achieved ≥50% VAF reduction, including 7 with complete elimination of the VAF. Reduction in other concurrent mutations was also observed in these pts. Safety was consistent with that previously reported; most frequent adverse events were reversible grade 3 or 4 thrombocytopenia and neutropenia. At the time of data cutoff (May 10, 2023), 13 pts receiving imetelstat and the pt receiving placebo were ongoing (Figure); of the 8 who discontinued treatment, 7 had loss of response, and 1 was due to adverse event. Analyses for progression-free and overall survival were not evaluable as of this cutoff date (insufficient follow-up). Treatment with imetelstat resulted in ≥1-year sustained, continuous TI in 17.8% of pts in the IMerge phase 3 trial. In this ESA-R/R/ineligible population with a high prior transfusion burden, a reduction to 0 RBC transfusions for ≥1 year represents an opportunity to achieve relief from iron overload and other transfusion associated complications, and decreased demand on already limited blood product supply. Furthermore, durable TI and meaningful reductions in mutational burden suggest imetelstat may have disease-modifying activity.
Background: Imetelstat, a 13-mer oligonucleotide that specifically targets the RNA template of human telomerase, is a potent competitive inhibitor of telomerase enzymatic activity (Asai Cancer Res ...2003; Herbert Oncogene 2005). Clinical activity and an acceptable safety profile were reported in a 33-patient pilot study in intermediate-2 (int-2) or high-risk myelofibrosis (MF), where 48% of patients had been previously treated with a Janus Kinase inhibitor (JAKi) (Tefferi N Engl J Med 2015). Here, we report the results of a phase 2 clinical study of imetelstat at two dose levels in patients with MF (MYF2001, NCT02426086).
Methods: A randomized, multicenter, phase 2 study of two doses of imetelstat (9.4 mg/kg or 4.7 mg/kg IV, every 3 weeks) was performed in adults with DIPSS int-2 or high-risk MF that was relapsed/refractory to prior JAKi therapy (ie, either no reduction in splenomegaly after 12 weeks or worsening splenomegaly at any time after the start of JAKi therapy). Diagnosis of primary, post-essential thrombocythemia, or post-polycythemia vera MF was required; other eligibility criteria included measurable splenomegaly (by magnetic resonance imaging MRI), active MF-related systemic symptoms and platelet count ≥75 x 109/L. Primary endpoints were spleen response rate (% achieving ≥ 35% spleen volume reduction SVR by MRI) and symptom response rate (% achieving ≥ 50% reduction in total symptom score TSS per Myelofibrosis Symptom Assessment Form (MFSAF) v2 at week 24. Key secondary endpoints included safety, overall survival (OS), treatment response, molecular response, and pharmacokinetic and pharmacodynamic relationships.
Results: 107 patients were enrolled at 55 institutions (48 on 4.7 mg/kg; 59 on 9.4 mg/kg). Baseline characteristics are shown in the Table. Additionally, median time on JAKi was 23 (0.9-89.7) mo, and median platelet count was 147 x 109/L. Triple-negative (TN; ie, no mutations of JAK2, MPL, or CALR) comprised 24.8% of patients and 67.6% were considered high molecular risk (HMR; ie, ≥ 1 mutation of ASXL1, EZH2, SRSF2, or IDH1/2).
At the time of clinical cutoff, patients were followed for a median 22.6 (0.2-27.4) mo, including a median treatment duration of 6.2 (0.0-27.2) mo. Median duration on treatment was longer on the 9.4 mg/kg arm (7.7 mo) than on the 4.7 mg/kg arm. Six (10.2%) patients in the 9.4 mg/kg arm had a spleen response per MRI, with no responses on the 4.7 mg/kg arm (Figure 1). Nineteen (32%) patients in the 9.4 mg/kg arm and 3 (6%) patients in the 4.7 mg/kg arm had a symptom response (TSS reduction ≥ 50%) (Figure 2).
Median OS in the 9.4 mg/kg arm has not been reached, while median OS was 19.9 mo in the 4.7 mg/kg arm. The 18-mo survival rates were 76.7% and 62.9% for the 9.4 mg/kg and 4.7 mg/kg arms, respectively. Sensitivity analyses censoring patients at time of dose escalation for subsequent JAKi therapy or allogeneic stem cell transplant generated similar results. In the 9.4 mg/kg arm, an association was observed between patients who were TN and OS (median OS has not been reached for TN patients and was 23.6 mo for non-TN patients). Spleen response rate was higher in patients with 1 HMR mutation (ASXL1, EZH2, SRSF2, or IDH1/2.
The most common adverse events on treatment (all grades) at 9.4 mg/kg were thrombocytopenia (49%), anemia (44%), neutropenia (36%), and nausea (34%) and at 4.7 mg/kg were diarrhea (38%), nausea (31%), anemia (31%), and thrombocytopenia (23%). Grade 3/4 neutropenia and thrombocytopenia were more frequent with 9.4 mg/kg (34% and 42%, respectively) than 4.7 mg/kg (13% and 29%, respectively); most cytopenias resolved within 4 weeks. Grade 3/4 LFT elevations were observed in 7 patients on study. Imetelstat-related hepatic toxicities, confirmed by an independent Hepatic Review Committee, were not observed.
Conclusions: Imetelstat at 9.4 mg/kg IV every 3 weeks has demonstrated clinical activity in int-2 or high-risk MF patients who are relapsed/refractory to JAKi, notably in observed OS. Though no formal study has reported survival for patients who are truly relapsed/refractory to JAKi, median OS of patients who were previously treated with JAKi has been reported to be 12-14 mo (Kuykendall Ann Hematol 2018; Newberry Blood 2017). The safety profile for imetelstat was considered acceptable for this poor-prognosis population. Imetelstat at 9.4 mg/kg IV every 3 weeks is a promising agent for JAKi-pretreated MF patients and warrants further testing in clinical trials.
Mascarenhas:Roche: Research Funding; Merck: Research Funding; Novartis: Research Funding; Promedior: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; CTI Biopharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees. Komrokji:Novartis: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Celgene: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Cavo:Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Niederwieser:Novartis: Research Funding; Miltenyi: Speakers Bureau. Reiter:Incyte: Consultancy, Honoraria. Scott:Celgene: Consultancy, Research Funding; Agios: Consultancy; Alexion: Consultancy; Novartis: Research Funding. Hoffman:Janssen: Research Funding; Merus: Research Funding; Incyte: Research Funding; Summer Road: Research Funding; Formation Biologics: Research Funding. Odenike:ABBVIE: Honoraria, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; CTI/Baxalta: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Dava Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncotherapy Science: Research Funding; Agios: Research Funding; Celgene: Research Funding; NS Pharma: Research Funding; Janssen: Research Funding; Astex: Research Funding; Gilead Sciences: Research Funding. Bussolari:Janssen: Employment, Equity Ownership. Zhu:Janssen: Employment, Equity Ownership. Huang:Janssen: Employment, Equity Ownership. Rose:Janssen: Employment, Equity Ownership. Sherman:Janssen: Employment, Equity Ownership. Dougherty:Janssen: Employment, Equity Ownership. Feller:Janssen: Employment, Equity Ownership. Kiladjian:AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.
Background: The presentation of acute myeloid leukemia (AML) as an extramedullary tumor occurs in up to 9% of cases, making it an uncommon event and one that poses difficulties in clinical ...decision-making. Current data on treatment and outcomes for myeloid sarcoma are based largely on case reports and clinician experiences involving a small number of patients. Radiation is often added to standard chemotherapy regimens in order to attempt to improve rates of complete remission, however there is a paucity of data to guide the utilization of radiation therapy in addition to chemotherapy.
Aims: To determine the impact of chemotherapy, the combination of chemotherapy and radiation therapy, and transplantation on the survival of patients with myeloid sarcoma.
Methods: Beginning with a PubMed search from 1985 to 2014, we performed a review of the literature on cases of isolated myeloid sarcomas (without bone marrow involvement) presenting as the initial diagnosis of AML. We identified 7 large case reports or reviews where individual patient characteristics (including treatment course, site of disease, overall survival (OS) and time to development of bone marrow involvement) were defined.
We also undertook a chart review of the patients treated at Memorial Sloan Kettering Cancer Center from 1990 to July 2014 who upon initial presentation of AML demonstrated extramedullary involvement. We excluded patients with extramedullary disease at relapse, those presenting with lymph node, splenic disease or leukemia cutis in both data sets. For the MSKCC data, we included those who presented with bone marrow involvement due to the low number of patients available for analysis.
Results: The literature search identified 71 analyzable patients and there was no significant difference in OS whether patients with isolated myeloid sarcoma were initially treated with radiation therapy (n= 14, 11.2 months), chemotherapy (n=40, 19 months) or the combination of chemotherapy and radiation (n=17, 24 months, p=0.41) Fig 1. The median OS of these patients was 16 months (n=71).
At MSKCC, 27 patients were available for analysis. The median 3 year OS of patients presenting with AML and extramedullary involvement was 41%. There was a significant improved 1 year OS (p=0.002) if patients were treated with chemotherapy alone (n=19), as opposed to the combination of radiation and chemotherapy (n=6), 89% vs. 33%, respectively. There was no difference in OS if patients presented with bone marrow involvement or with isolated disease (35% vs. 55% at 3 years, p= 0.51). Lastly, patients who underwent allogeneic stem cell transplantation (n=13) exhibited a median 44% 3 year OS. Only seven of these patients were in first complete remission.
Summary/ Conclusion: Patients with AML who present with extramedullary disease seem to derive no additional survival benefit from the inclusion of radiation therapy to chemotherapy as initial treatment. Also, presentation with isolated myeloid sarcoma does not appear to confer a worse prognosis when compared to myeloid sarcoma with bone marrow involvement and likely represents a different manifestation of the same disease process. For comparison, regarding overall survival, patients enrolled in ECOG 1900 who received standard therapy had a median OS of 15.7 months and those with intermediate risk cytogenetics and an intermediate risk mutational risk profile, as described by Patel et al in NEJM 2012, had a 3 year OS of 42% comparable to the outcomes we noted above. This suggests that patients with myeloid sarcoma do no worse than those with bone marrow only disease.
The survival of patients who underwent allogeneic stem cell transplantation in our study had a similar median 3 year OS to patients with AML who undergo allogeneic stem cell transplantation studied by the CIBMT and published in Blood 2012 by Saber et al. The 3 year OS rates for patients who underwent a matched related donor transplant in this publication was 39%, and 37% for those who had a matched unrelated donor transplant.
In summary, though the sample size is notably small and acknowledging the limitations of retrospective data, patients with myeloid sarcoma during the initial presentation of AML should undergo risk stratification and treatment in the same manner as patients with AML without extramedullary disease.
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No relevant conflicts of interest to declare.
Patients with lower-risk (LR) myelodysplastic syndromes (MDS) who are RBC transfusion dependent and have experienced relapse after or are refractory to erythropoiesis-stimulating agent (ESA) have ...limited treatment options. High telomerase activity and human telomerase reverse-transcription expression in clonal hematopoietic cells have been reported in patients with MDS. Imetelstat, a first-in-class competitive inhibitor of telomerase enzymatic activity, targets cells with active telomerase. We report efficacy, safety, and biomarker data for patients with LR MDS who are RBC transfusion dependent and who were relapsed/refractory to ESAs.
In this two-part phase II/III study (MDS3001), the primary end point was 8-week RBC transfusion independence (TI) rate, with key secondary end points of 24-week RBC TI rate, TI duration, and hematologic improvement-erythroid.
Data from the phase II part of the study are reported. Of 57 patients enrolled and treated (overall population), 38 were non-del(5q) and hypomethylating agent and lenalidomide naïve (subset population). The 8- and 24-week RBC TI rates in the overall population were 37% and 23%, respectively, with a median TI duration of 65 weeks. In the subset population, 8- and 24-week RBC TI rates were 42% and 29%, respectively, with a median TI duration of 86 weeks. Eight-week TI rate was observed across all subgroups evaluated. Cytogenetic and mutational data revealed a reduction of the malignant clones, suggesting disease modification activity. The most common adverse events were cytopenias, typically reversible within 4 weeks.
Imetelstat treatment results in a meaningful, durable TI rate across a broad range of heavily transfused patients with LR MDS who are ineligible for or relapsed/refractory to ESAs. Biomarker analyses indicated effects on the mutant malignant clone.
Unmet medical needs remain in patients with red blood cell transfusion-dependent (RBC-TD) lower-risk myelodysplastic syndromes (LR-MDS) who are not responding to or are ineligible for ...erythropoiesis-stimulating agents (ESAs). Imetelstat, a competitive telomerase inhibitor, showed promising results in a phase 2 trial. We aimed to compare the RBC transfusion independence (RBC-TI) rate with imetelstat versus placebo in patients with RBC-TD LR-MDS.
In phase 3 of IMerge, a double-blind, placebo-controlled trial conducted in 118 sites including university hospitals, cancer centres, and outpatient clinics in 17 countries, patients (aged ≥18 years) with ESA-relapsed, ESA-refractory, or ESA-ineligible LR-MDS (low or intermediate-1 risk disease as per International Prognostic Scoring System IPSS criteria) were randomly assigned via a computer-generated schedule (2:1) to receive imetelstat 7·5 mg/kg or placebo, administered as a 2-h intravenous infusion, every 4 weeks until disease progression, unacceptable toxic effects, or withdrawal of consent. Randomisation was stratified by previous RBC transfusion burden and IPSS risk group. Patients, investigators, and those analysing the data were masked to group assignment. The primary endpoint was 8-week RBC-TI, defined as the proportion of patients without RBC transfusions for at least 8 consecutive weeks starting on the day of randomisation until subsequent anti-cancer therapy, if any. Primary efficacy analyses were performed in the intention-to-treat population, and safety analyses were conducted in patients who received at least one dose of trial medication or placebo. This trial is registered with ClinicalTrials.gov (NCT02598661; substudy active and recruiting).
Between Sept 11, 2019, and Oct 13, 2021, 178 patients were enrolled and randomly assigned (118 to imetelstat and 60 to placebo). 111 (62%) were male and 67 (38%) were female. 91 (77%) of 118 patients had discontinued treatment by data cutoff in the imetelstat group versus 45 (75%) in the placebo group; a further one patient in the placebo group did not receive treatment. Median follow-up was 19·5 months (IQR 12·0–23·4) in the imetelstat group and 17·5 months (12·1–22·7) in the placebo group. In the imetelstat group, 47 (40% 95% CI 30·9–49·3) patients had an RBC-TI of at least 8 weeks versus nine (15% 7·1–26·6) in the placebo group (rate difference 25% 9·9 to 36·9; p=0·0008). Overall, 107 (91%) of 118 patients receiving imetelstat and 28 (47%) of 59 patients receiving placebo had grade 3–4 treatment-emergent adverse events. The most common treatment-emergent grade 3–4 adverse events in patients taking imetelstat were neutropenia (80 68% patients who received imetelstat vs two 3% who received placebo) and thrombocytopenia (73 62% vs five 8%). No treatment-related deaths were reported.
Imetelstat offers a novel mechanism of action with durable transfusion independence (approximately 1 year) and disease-modifying activity for heavily transfused patients with LR-MDS who are not responding to or are ineligible for ESAs.
Janssen Research & Development before April 18, 2019, and Geron Corporation thereafter.
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