Mead, Adam J.

Abstract MAJIC is a phase II trial of Ruxolitinib (RUX) vs Best Available Therapy (BAT) in essential thrombocythemia (ET) patients with resistance/intolerance to Hydroxycarbamide (HC) per European LeukemiaNet (ELN) criteria. Primary outcome was rate of complete hematological response (CHR) within 1 year (ELN criteria); secondary outcomes included partial HR, safety, thrombosis, hemorrhage, progression free survival (including transformation), molecular response (MR), symptom & quality of life (QOL) assessment. We present new data concerning molecular, symptom & clinical responses. Patients were stratified by JAK2V617F status, patient-reported symptoms & QOL determined using EQ5D, MDASI & MPN Symptom Assessment Form (MPN10), & compared using linear mixed models of post-baseline scores through month 12 adjusting for baseline; response was defined as ≥50% reduction in MPN10 total symptom score (TSS). JAK2/CALR/MPL allele burdens were assessed at baseline & 4 monthly. 110 patients were eligible for the modified ITT analysis, 58 (52%) & 52 (48%) in RUX & BAT arms respectively, comprising 44 males, 66 females, mean age 64.2ys, & resistant (24.5%), intolerant (51.8%) or both (22.7%) to HC. CHR was achieved in 27 (46.6%) of RUX patients vs 23 (44.2%) BAT patients (χ2 test p= 0.81). PHR occurred in 26 (44.8%) & 27 (51.9%) of RUX & BAT treated respectively. Grade 3 or 4 anemia occurred in 19% & 0% for RUX arm vs 0% (both grades) for BAT arm, grade 3 or 4 thrombocytopenia in 5.2% & 1.7% of RUX vs 0% (both grades) of BAT patients respectively. Grade 3 or 4 infections occurred in 10.3% of RUX patients vs 3.6% BAT arm. 9 RUX treated patients had 10 thrombotic events & 1 RUX patient a hemorrhage; vs 5 thrombotic & 5 hemorrhagic events in BAT patients (adjusted following central review). Transformations to post-ET MF occurred in 8 RUX vs 3 BAT treated patients, 1 RUX patient developed AML. 2 non-treatment related deaths occurred in each arm. Mean MPN-10 TSS & individual symptoms of early satiety & itching during the first 12 months were all significantly lower for RUX vs BAT (all p<0.05). Patients who achieved CHR had significantly better TSS, fatigue, inactivity, concentration problems, & MDASI symptom interference (all p<0.05) at baseline vs those without; however, scores during treatment did not appear to differ between CHR & non CHR groups after adjusting for these baseline differences. Allele burden during study & MRs (per ELN-IWG criteria Barosi Blood 2013) are shown in Table 1. Assays for JAK2 V617F were performed independently in 3 centres using qPCR (Guy's), TSCA NGS (Oxford) & amplicon-based NGS (Salisbury) & revealed Mean (range): JAK2 (Guy's): 33.2 (0.1-94.6), N=52; JAK2 (Oxford): 38.0 (0.5-92.2), N=52; JAK2 (Sal): 38.3 (0-90.0), N=50 (limited to JAK2 positive only). With Interclass Correlation Coefficient as follows ICC (Guy's v Oxford): 0.92 (95% CI 0.86-0.95) ICC (Guy's v Sal): 0.92 (95% CI 0.86-0.95) ICC (Oxford v Sal): 0.997 (95% CI 0.994-0.998). Notably MRs (n=5) only occurred with RUX treatment. There was no pattern of MR or progression with C/PHR or transformation, but 1 patient who transformed to PET MF had a complete MR. In a separate analysis baseline symptoms & QOL were not associated with JAK2, CALR, nor MPL status. Within RUX, baseline symptoms & QOL did not predict MR; however, fatigue, early satiety & abdominal discomfort (all p<0.05, Table 1) were significantly lower among those with MR vs not during treatment with a descriptively higher symptom response rate (2/4 [50%] vs 9/30 [30%]). Three non pre-specified multivariate analyses were performed to assess baseline factors influencing CHR (modelled for: treatment received, HC resistance or intolerance, white cell count, platelets, Hb & JAK2/CALR status); occurrence of ≥ grade 3 anemia or thrombocytopenia (modelled for: Hb (≥ 100g/dl) JAK2/CALR status); & transformation to PET-MF (modelled for: treatment, Hb ≤100g/dl). Only baseline Hb ≤100g/dl was significant for grade 3+ anemia (OR [95% CI]=0.17 [0.04, 0.72]), & PET-MF only occurred in patients with baseline WBC <10x109/L. This updated analysis shows that HC resistant/intolerant ET is clinically & molecularly diverse. We confirm that these patients are at high risk of thrombosis & transformation as suggested in prior retrospective studies. Molecular responses were limited to RUX & for the first time we demonstrate such responses may correlate with symptom improvement but not always with progression events. Disclosures Harrison: Shire: Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Incyte Corporation: Honoraria, Speakers Bureau; Baxaltra: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: travel, accommodations, expenses, Research Funding, Speakers Bureau. Mead:Novartis: Honoraria, Research Funding, Speakers Bureau. Aliman:Novartis: Other: Institutional funding and grant for international conference. . Chen:Novartis: Other: Advisory Board. Coppell:Novartis: Other: Travel, accommodation and conference attendance. Knapper:ONO pharmaceuticals: Research Funding; Novartis: Honoraria, Other: Travel and expenses for international conferences. Ali:Novartis: Honoraria, Other: Conference sponsorship, advisory board meetings. Hamblin:Novartis: Other: Advisory Board. Dueck:Bayer: Honoraria. Cross:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau. Mesa:Celgene: Research Funding; Promedior: Research Funding; CTI: Research Funding; Gilead: Research Funding; Incyte: Research Funding; Galena: Consultancy; Ariad: Consultancy; Novartis: Consultancy. McMullin:Novartis: Honoraria, Speakers Bureau.

Abstract Background: Cytoreductive therapy with hydroxyurea (HU) has been considered first line therapy for patients with high risk polycythemia vera (PV) and essential thrombocythemia (ET) since the results of the PVSG-08 trial demonstrated thrombotic risk reduction (Fruchtman SM et al 1997) for PV and PT1 for ET (Harrison CN et al 2005). Although HU is well tolerated by most patients and has been shown to reduce thrombotic risk in this setting, concern regarding the leukemogenic potential of this oral ribonucleotide reductase inhibitor balanced by the observation of molecular responses with interferon-α (IFN-α) led us to compare the clinical response and tolerability of pegIFN-α (PEG) and HU in a global, randomized, phase III trial. Methods : MPD-RC 112 trial (NCT01258856) enrolled patients with high risk (age >60 years, history of thrombosis, extreme thrombocytosis, symptomatic splenomegaly, uncontrolled cardiovascular risk factors), newly diagnosed (<5 years), WHO defined ET/PV that were treatment naïve (HU <3 months) and randomized (1:1) to PEG or HU. The primary endpoint was complete hematologic response (CHR) rate by European LeukemiaNet (ELN) criteria between the arms after 12 months of therapy. A planned interim analysis based on intent-to-treat with testing boundaries for efficacy and futility was conducted after 75 patients were on study for 12 months. Response assessment by ELN criteria were conducted by blinded review by 4 investigators (JM, RAM, AY, RH). Intent-to-treat analysis was conducted for efficacy endpoints (HU n=39; PEG n=36). Safety analysis included all patients who received treatment (HU n=36; PEG n=36). Results: Patients: The MPD-RC 112 trial involved 24 centers in 6 countries; enrollment began 09/2011 and concluded 7/2016 prior to full accrual due to study drug availability with 168 patients enrolled (Table 1 for 75 patients in the interim analysis). There was no imbalance between arms with respect to history of thrombosis, erythromelalgia, diabetes, hypertension, but age was significantly older on HU. This remained true when analyzing by ET/PV disease strata with the exception of diabetes which was slightly imbalanced within the PV cohort (HU 5/23, 22%; PEG 0/21, 0%; p<0.05). Response: CHR and PHR were observed in 13 (33%) and 14 (36%) patients for an overall response rate (ORR) of 69% (27/39) for HU, and 10 (28%) and 19 (53%) for an ORR of 81% (29/36) for PEG (CHR comparison p=0.60 based on z-test which did not cross either testing boundary). 10 patients randomized to HU were not evaluable for 12-month response due to never initiating treatment (n=3) or early study discontinuation for AEs (n=1), patient withdrawal (n=5), or treatment non-compliance (n=1). 3 patients were not evaluable for response on PEG due to early study discontinuation for AEs (n=1), physician decision (n=1), or patient withdrawal (n=1). Excluding patients who never initiated treatment did not impact the primary endpoint comparison (HU 13/36, 36%; PEG 10/36, 28%; p=0.45). For ET, CHR and PHR were observed in 7 (44%) and 4 (25%) patient on HU, and 6 (40%) and 6 (40%) for PEG (CHR comparison p=0.83). For PV, CHR and PHR were observed in 6 (26%) and 10 (44%) patients on HU, and 4 (19%) and 13 (62%) for PEG (CHR comparison p=0.58). Normalization of spleen by palpation at 12 months was seen in 2/7 (29%) and 5/7 (71%) of the HU and PEG treated patients with palpable spleen at baseline, respectively. Among 38 PV patients, rate of phlebotomy use at 12 months was 0/18 (0%) vs 5/20 (20%) on HU and PEG (p=0.02). From baseline to best score through 12 months, 9/28 (32%) and 12/34 (35%) patients with data on HU and PEG, respectively, had a ≥50% reduction in MPN-SAF Total Symptom Score (p=0.79). Toxicity: No Grade 4 AEs occurred in either treatment arm. Overall, Grade 3 AEs occurred in 5/36 (14%) HU patients and 16/36 (44%) PEG patients (Grade 3 hematologic: 4/36 [11%] HU vs 8/36 [22%] PEG; Grade 3 non-hematologic: 5/36 [14%] HU vs 16/36 [44%] PEG). See Table 2 for Grade 3 AEs regardless of attribution occurring in >10% of patients in either arm. Conclusions: This interim analysis does not show a clear difference in primary endpoint of CHR between HU and PEG. A comparative analysis of the quality of life and symptom burden will provide further insight into the tolerability of these agents (Mesa et al ASH 2016). The final results of this pivotal trial will provide necessary data required to firmly establish the optimal first line therapy for patients with high risk ET/PV. Disclosures Mascarenhas: CTI Biopharma: Research Funding; Janssen: Research Funding; Promedior: Research Funding; Roche: Research Funding; Novartis: Other: DSMB , Research Funding; Incyte: Other: Clinical Trial Steereing Committee, Research Funding. Mesa:Celgene: Research Funding; Promedior: Research Funding; CTI: Research Funding; Gilead: Research Funding; Incyte: Research Funding; Galena: Consultancy; Ariad: Consultancy; Novartis: Consultancy. Yacoub:Alexion: Honoraria; Seattle Genetics: Consultancy, Honoraria, Speakers Bureau; Incyte: Consultancy, Honoraria, Speakers Bureau. Harrison:Baxaltra: Consultancy, Honoraria, Speakers Bureau; Incyte Corporation: Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Shire: Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: travel, accommodations, expenses, Research Funding, Speakers Bureau. McMullin:Novartis: Honoraria, Speakers Bureau. Vannucchi:Novartis: Honoraria, Speakers Bureau. Kiladjian:Novartis: Honoraria, Research Funding; AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding. Mead:Novartis: Honoraria, Research Funding, Speakers Bureau. Kessler:Incyte: Honoraria. Ritchie:Celgene: Consultancy, Other: Travel, Accomodations, Expenses, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Novartis: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Ariad: Speakers Bureau; Pfizer: Consultancy, Research Funding; Astellas Pharma: Research Funding; Bristol-Meyers Squibb: Research Funding; NS Pharma: Research Funding. Schlenk:Amgen: Research Funding; Pfizer: Honoraria, Research Funding.

Abstract Background: The majority of pts with MF present with a mutation in exon 14 of the JAK2 gene (JAK2V617F). Studies have suggested that in pts with MF and this mutation, a lower AB is associated with a myelodepletive phenotype and shortened survival (Tefferi, Leukemia 2008; Guglielmelli Blood 2009; reviewed in Vannucchi, Ther Adv Hematol 2011). For example, in a Cox proportional hazard model for factors predictive of overall survival (OS) in pts with primary MF, a JAK2V617F AB of <25% was associated with a shortened OS (p=0.002; Guglielmelli, Blood 2009). In the phase III trials of ruxolitinib (RUX) therapy in JAK inhibitor-naïve MF, RUX-treated pts had a median decrease in AB of 16% (maximal) in COMFORT-I followed up to 216 weeks and 7% in COMFORT-II at 48 weeks. The median AB at the start of therapy was not reported for COMFORT-I and in COMFORT-II was 84.5% (Cervantes, Blood 2013; Deininger, Blood2015). Methods: In this communication, we report on clinical correlates of quantitative baseline JAK2 mutational status and the effect of treatment on JAK2V617Fmutational burden in the PERSIST-1 trial. This trial enrolled JAK inhibitor-naïve pts with primary or secondary MF without restrictions on baseline platelet counts, randomized 2:1 between PAC and BAT (excluding JAK2 inhibitors) arms. Stratifications included Dynamic International Prognostic Scoring System (DIPSS) risk category, and baseline platelet counts (<50,000/μL, 50,000-100,000/μL, >100,000/μL). Following the 24-week primary analysis, crossover was allowed by physician/pt choice and 90/107 BAT-treated pts (84%) crossed over to receive PAC. Baseline characteristics have been previously reported (Mesa, ASCO 2016) and included 203/327 (62%) pts with Primary MF, 42 (13%) with post-essential thrombocythemia MF and 81 (25%) with post-polycythemia vera MF. 320 of 327 pts had informative PCR testing for JAK2V617F. We report the baseline characteristics of pts with high (≥50%) AB of JAK2V617F, low (<50%) AB of JAK2V617Fand those without a detectable mutation at baseline (<0.1%), as well as the effect of PAC and BAT on AB and correlation with outcome measures. Results: 131 (40.9%) had AB >50% (high AB), 115 (35.9%) had an AB ≥0.1% and ≤50% (low AB), and 74 (23.1%) had AB <0.1% (wild-type JAK2). Median AB values were 80.3% for the high AB group and 30.3% for the low AB group. Baseline characteristics that were significantly different between high and low AB pts are shown in the Table. No differences were noted in the DIPSS risk category or baseline percentage of blasts between pts with low or high AB. There were a higher percentage of pts with a lower AB in the PAC arm (64% vs. 48%; p=0.01). PAC therapy resulted in a median decrement in AB at Week 24 of −15.8% vs −7.9% for pts in the BAT arm (Figure). The median greatest reduction from baseline in AB in PAC-treated pts was −31.6%. Decrease in AB was strongly correlated with spleen volume reduction (p=0.003) and trended towards correlation with improvement in total symptom score (p=0.07) in PAC-treated, but not in BAT-treated pts. Overall survival was shorter in PAC-treated pts with a minimal AB reduction vs pts with greater decreases in AB. Conclusions: In the PERSIST-1 trial, pts with a JAK2V617FAB of <50% had substantially different disease and demographic characteristics when compared with those pts with a >50% AB despite similar distribution of DIPSS scores. In this trial, reduction in AB associated with PAC, but not BAT correlated with clinical benefit. Disclosures Vannucchi: Novartis: Consultancy, Research Funding, Speakers Bureau; Baxalta: Speakers Bureau; Shire: Speakers Bureau. Mead:Baxalta: Consultancy, Honoraria. Perkins:Novartis Oncology: Consultancy, Honoraria; Bristol-Myers Squibb: Other: Travel, Accommodations, Expenses. Mayer:CTI BioPharma Corp.: Other: Travel, Accommodations, Expenses, Research Funding. Schouten:Sanofi: Consultancy; Novartis: Consultancy. Farber:Alexion: Equity Ownership; Celgene: Honoraria, Research Funding, Speakers Bureau; Genentech: Research Funding, Speakers Bureau; Acerta: Research Funding; Gilead: Research Funding, Speakers Bureau; TG Therapeutics: Research Funding; Seattle Genetics: Speakers Bureau; Pharmacyclics: Speakers Bureau. Kiladjian:Novartis: Honoraria, Research Funding; AOP Orphan: Consultancy, Research Funding. Nangalia:Novartis: Consultancy, Other: Travel, Accommodations, Expenses. Dean:CTI BioPharma Corp.: Employment, Equity Ownership. Zhou:CTI BioPharma Corp.: Employment, Equity Ownership. Singer:CTI BioPharma Corp.: Employment, Equity Ownership, Other: Leadership . Mesa:Novartis: Consultancy, Honoraria; Incyte: Research Funding; Gilead: Research Funding; CTI BioPharma: Research Funding; Celgene: Research Funding; Genetech: Research Funding; Promedior: Research Funding. Harrison:Novartis: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; CTI BioPharma: Consultancy, Honoraria, Speakers Bureau; Baxter: Consultancy, Honoraria; Shire: Speakers Bureau; Gilead: Speakers Bureau; Incyte: Speakers Bureau.

Key Points After hydroxycarbamide therapy in high-risk ET, ruxolitinib showed no improvement for complete or partial response rates compared with BAT. Ruxolitinib significantly improved some disease-related symptoms, but rates of thrombosis, hemorrhage, or transformation were not different.

LBA7006 Background: PAC is a potent JAK2 inhibitor without significant JAK1 inhibition with minimal myelosuppression in early-phase studies in MF. Methods: The efficacy and safety of daily oral PAC was compared to BAT (2:1 randomization stratified for risk and platelet count). The 10 endpoint was the proportion of ITT patients (pts) achieving ≥ 35% spleen volume reduction (SVR) at week (wk) 24 by centrally reviewed MRI or CT. Secondary endpoints included the proportion achieving ≥ 50% reduction in total symptom score (TSS) at wk 24 using the MPN Symptom Assessment Form. Results: Patients:327 were enrolled (PAC:220, BAT:107), 62% with 10 MF. Median time from diagnosis was 1.12 years (PAC 0.99, BAT 1.60): 32% and 15% had a platelet counts < 100,000/µL or <50,000/ µL; 75% were JAK2V617F positive. Efficacy: The median duration of treatment was 16.2 months PAC and 5.9 months BAT. Sixty-two percent of BAT patients received active disease directed therapy. The SVR rates at week 24 were 19.1% for PAC vs. 4.7% for BAT (p=0.0003) in ITT and 25% vs. 5.9% (p=0.0001) in the evaluable population. 79% of BAT patients crossed over to PAC; 21% had achieved a >35% reduction in spleen volume at data cutoff. TSS composite V1 + V2 response rates were 24.5%for PAC vs. 6.5% for BAT (p<0.0001) by ITT, and were 40.9% vs. 9.9% in evaluable pts (p<0.0001). Efficacy with baseline cytopenias: In pts with <100,000 and <50,000 platelets/μ/L, the SVR rates were 16.7% for PAC vs. 0% for BAT (p=0.009), and 22.9% vs. 0% (p=0.045) by ITT and 23.5% vs. 0% (p=0.007) and 33.3% vs. 0% (p=0.037) in evaluable pts. In RBC transfusion dependent pts, 25.7% of PAC pts became RBC independent vs. 0% of BAT pts (p=0.043). Safety: The most common adverse events (AE) for PAC were diarrhea, nausea, and vomiting; (grade 3 were <5%, <1%, <1% respectively). Hematologic AEs were similar between PAC and BAT. Conclusions: This study demonstrated PAC was well tolerated and induced significant and sustained SVR and symptom control even in patients with severe thrombocytopenia. PAC therapy resulted in RBC transfusion independence in a significant proportion of pts. Clinical trial information: NCT01773187.