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Purpose: Treatment options are limited beyond JAK inhibitors for patients with primary myelofibrosis (MF) or secondary MF. Preclinical studies have revealed that PI3Kδ inhibition cooperates with ruxolitinib, a JAK1/2 inhibitor, to reduce proliferation and induce apoptosis of JAK2V617F-mutant cell lines. Patients and Methods: In a phase I dose-escalation and -expansion study, we evaluated the safety and efficacy of a selective PI3Kδ inhibitor, umbralisib, in combination with ruxolitinib in patients with MF who had a suboptimal response or lost response to ruxolitinib. Enrolled subjects were required to be on a stable dose of ruxolitinib for ≥8 weeks and continue that MTD at study enrollment. The recommended dose of umbralisib in combination with ruxolitinib was determined using a modified 3+3 dose-escalation design. Safety, pharmacokinetics, and efficacy outcomes were evaluated, and spleen size was measured with a novel automated digital atlas. Results: Thirty-seven patients with MF (median age, 67 years) with prior exposure to ruxolitinib were enrolled. A total of 2 patients treated with 800 mg umbralisib experienced reversible grade 3 asymptomatic pancreatic enzyme elevation, but no dose-limiting toxicities were seen at lower umbralisib doses. Two patients (5%) achieved a durable complete response, and 12 patients (32%) met the International Working Group-Myeloproliferative Neoplasms Research and Treatment response criteria of clinical improvement. With a median follow-up of 50.3 months for censored patients, overall survival was greater than 70% after 3 years of follow-up. Conclusions: Adding umbralisib to ruxolitinib in patients was well tolerated and may resensitize patients with MF to ruxolitinib without unacceptable rates of adverse events seen with earlier generation PI3Kδ inhibitors. Randomized trials testing umbralisib in the treatment of MF should be pursued.

Supplemental Tables S1-S9 Supplemental Figures S1-S2

Purpose:Treatment options are limited beyond JAK inhibitors for patients with primary myelofibrosis (MF) or secondary MF. Preclinical studies have revealed that PI3Kδ inhibition cooperates with ruxolitinib, a JAK1/2 inhibitor, to reduce proliferation and induce apoptosis of JAK2V617F-mutant cell lines.Patients and Methods:In a phase I dose-escalation and -expansion study, we evaluated the safety and efficacy of a selective PI3Kδ inhibitor, umbralisib, in combination with ruxolitinib in patients with MF who had a suboptimal response or lost response to ruxolitinib. Enrolled subjects were required to be on a stable dose of ruxolitinib for ≥8 weeks and continue that MTD at study enrollment. The recommended dose of umbralisib in combination with ruxolitinib was determined using a modified 3+3 dose-escalation design. Safety, pharmacokinetics, and efficacy outcomes were evaluated, and spleen size was measured with a novel automated digital atlas.Results:Thirty-seven patients with MF (median age, 67 years) with prior exposure to ruxolitinib were enrolled. A total of 2 patients treated with 800 mg umbralisib experienced reversible grade 3 asymptomatic pancreatic enzyme elevation, but no dose-limiting toxicities were seen at lower umbralisib doses. Two patients (5%) achieved a durable complete response, and 12 patients (32%) met the International Working Group-Myeloproliferative Neoplasms Research and Treatment response criteria of clinical improvement. With a median follow-up of 50.3 months for censored patients, overall survival was greater than 70% after 3 years of follow-up.Conclusions:Adding umbralisib to ruxolitinib in patients was well tolerated and may resensitize patients with MF to ruxolitinib without unacceptable rates of adverse events seen with earlier generation PI3Kδ inhibitors. Randomized trials testing umbralisib in the treatment of MF should be pursued.

Background Ibrutinib is approved for a variety of B-cell malignancies, including CLL and MCL, and for chronic GVHD (cGVHD), failing ≥ 1 line of systemic therapy. Allogeneic HCT is curative for CLL and MCL, but success is limited due to relapse or GVHD morbidity/mortality. We hypothesized that use of ibrutinib early post HCT would optimize outcomes by improving progression-free survival (primary outcome) and decrease incidence of moderate-severe cGVHD (secondary endpoint). We describe our findings regarding safety and feasibility in the first 16 patients (NCT02869633). Methods Adult patients (pts) undergoing T-replete HCT from related or unrelated donors (7/8 or 8/8) without post-transplant cyclophosphamide for CLL (>CR1, or after 1st line if 17p) or MCL (>CR1, or after 1st line if blastoid variant) were enrolled, along with an exploratory cohort of FL and HL (max 10 patients). Use of ibrutinib prior to HCT was permissible. Enrollment was prior to HCT, but pts had to meet secondary eligibility criteria to ensure no critical illness, adequacy of graft and organ function, prior to starting ibrutinib (420 mg daily) between day 60-90. Ibrutinib was continued until 12 m post HCT. Results Sixteen pts (CLL 44%, MCL 13%, FL 25%, HD 13%), median age 49.5 y, underwent HCT from unrelated (94%) or related donors (6%), that were 8/8 (88%) or 7/8 (12%) HLA matched, at a median of 30.2 m after diagnosis. Median follow up from HCT is 5.1 m and 1 y survival is 75%. Regimens included FCR-thymoglobulin (44%), TLI-ATG (31%), Flu Bu (13%) or Flu Mel (12%). GVHD prophylaxis was tacrolimus-MTX (69%) or CSA-MMF (31%). Of the 14 pts eligible to start ibrutinib (> 60 d post HCT), 9 started ibrutinib (64%), while 5 did not (4-not meet secondary eligibility criteria, 1-physician preference). The median starting dose was 140 mg (protocol specified due to drug interactions). Of the 9 pts who started ibrutinib, 2 (22%) had to stop it prematurely (cytopenias, confounded by concomitant medications), 3 (33%) completed therapy and 4 (45%) are on therapy. Table 1 outlines key ≥ grade 3 adverse events (AEs) at any time point after enrollment. In this group of 9 pts, aGVHD grade 0, 1, 3 and 4 was seen in 57%, 22%, 7% and 14%, and cGVHD was seen in 3 pts (7%-mild, 14%-severe). No pts had progression of disease (CR-67%, PR-11%, SD-22%); 2 pts are deceased (1-infection at 14 m post HCT in CR, and 1 from acute GVHD (onset prior to start of ibrutinib with SD). Conclusions Our data in this ongoing study shows that majority of patients could initiate early post HCT ibrutinib and most are expected to tolerate it until 1 y post HCT. No unexpected side effects have been seen with use of ibrutinib early post HCT, and there have been no relapses.

Background: Therapies for myelofibrosis (MF) are limited and most are palliative. The JAK1/2 inhibitor ruxolitinib reduces spleen size and MF-related symptoms and improves survival, but can be limited by dose-dependent anemia and thrombocytopenia. Moreover, nearly half of ruxolitinib responders relapse within 5 years. PI3Kd is highly expressed in MF patient samples, independent of ruxolitinib pre-exposure. In JAK2-mutated cell lines, inhibition of PI3K/AKT signaling reduced proliferation and clonogenic potential. The once daily, next generation PI3Kd inhibitor TGR-1202 inhibited PI3K/AKT signaling and led to apoptosis in leukemia and lymphoma cell lines and was well-tolerated in clinical studies, with a toxicity profile distinct from that of ruxolitinib and other PI3Kd inhibitors. We hypothesized that adding TGR-1202 to ruxolitinib could resensitize or augment the response of MF patients with lost or suboptimal response to single-agent ruxolitinib. Objective: To assess safety of TGR-1202 in combination with ruxolitinib in MF patients Secondary Objectives: Hematologic response, symptom assessment Methods: MF patients who had sub-optimal responses to ruxolitinib continued their highest tolerated dose of ruxolitinib without change for ≥ 8 weeks, and were assigned to escalating doses of TGR-1202 in a standard 3+3 algorithm. Adverse events (AEs) were graded by NCI-CTCAE v4.03. Efficacy was assessed according to IWG-MRT consensus response criteria. Symptoms were assessed by the MPN symptom assessment form total symptom score (TSS). All patients received Pneumocystis pneumonia prophylaxis after cycle 1. Results: Eleven MF patients were enrolled and received 400 mg (n=3), 800 mg (n=6), or 600 mg TGR-1202 (n=2) daily. Nine were evaluable for response. Median age was 66y, 73% were male. All had ECOG PS 0-1. Five patients had mutations in JAK2, 4 in CALR, and 3 in MPL; these were mutually exclusive with exception of 1 patient with CALR and MPL mutations (Table 1). Median number of cycles of TGR-1202 + ruxolitinib treatment was 5 (1-13). Grade 2 anemia was the most common AE (Table 2). Two patients had asymptomatic Grade 3 elevations in amylase and lipase that persisted after drug was held, meeting criteria for dose limiting toxicities (DLTs) in 2 separate cohorts (TGR-1202 800mg+ruxolitinib 15mg BID and TGR-1202 800mg+ruxolitinib 10mg BID). Both patients had peak plasma TGR-1202 concentrations 1.5-2x higher than the other patients receiving 800mg TGR-1202, although steady-state levels were equivalent. The maximum tolerated dose (MTD) of TGR-1202 in combination with ruxolitinib was not established. Two patients went off-study due to AEs, and 3 due to progressive disease. One of 9 evaluable patients achieved complete remission and 7 had stable disease. Seven of the 9 evaluable patients had improvement in hematologic parameters and 8 had reduced MF symptoms with a median 33% decrease in TSS (Fig. 1). Conclusions: TGR-1202 + ruxolitinib was well-tolerated. Pharmacokinetic data were consistent with single-agent TGR-1202 (unpublished data), indicating that ruxolitinib does not alter absorption or metabolism of TGR-1202. Grade 3 elevations in amylase and lipase were considered DLTs, per protocol. Although the clinical significance of these asymptomatic laboratory findings is not clear, the protocol was amended to further assay these labs and to exclude concomitant medications with the potential to increase amylase/lipase. Importantly, no grade ≥3 hepatotoxicity, colitis, or thrombocytopenia was seen and no MTD was found. Although only one patient achieved CR, 89% demonstrated clinical benefit with the addition of TGR-1202 to ruxolitinib, supporting further exploration of this combination. Disclosures Strickland: Alexion Pharmaceuticals: Consultancy; Ambit: Consultancy; Baxalta: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding; CTI Biopharma: Consultancy; Daiichi Sankyo: Consultancy; Sunesis Pharmaceuticals: Consultancy, Research Funding; Abbvie: Research Funding; Astellas Pharma: Research Funding; Celator: Research Funding; Cyclacel: Research Funding; GlaxoSmithKline: Research Funding; Karyopharm Therapeutica: Research Funding; Sanofi: Research Funding. Miskin:TG Therapeutics, Inc: Employment, Equity Ownership. Cavers:TG Therapeutics: Employment, Equity Ownership. Sportelli:TG Therapeutics, Inc.: Employment, Equity Ownership. Michaelis:Pfizer: Equity Ownership; Cellgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte Corporation: Consultancy, Honoraria. Mesa:CTI: Research Funding; Promedior: Research Funding; Celgene: Research Funding; Gilead: Research Funding; Incyte: Research Funding; Galena: Consultancy; Ariad: Consultancy; Novartis: Consultancy. Savona:Amgen Inc.: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Research Funding; Ariad: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Sunesis: Research Funding; Incyte: 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; Gilead: Membership on an entity's Board of Directors or advisory committees.

Background: Retrospective studies have shown that achieving minimal residual disease (MRD) by multi-parameter flow cytometry (MFC) is predictive of outcomes in multiple myeloma (MM). Modern induction therapies including bortezomib (V), lenalidomide (R) followed by autologous hematopoietic cell transplant (AHCT) have resulted in substantial improvements in progression free survival (PFS) and overall survival (OS). The impact of bortezomib-based therapy on end of induction chemotherapy MRD status and post-AHCT MRD status is not well defined. We designed a prospective clinical trial (NCT01215344) to study the incidence of MRD negativity at end of induction and following AHCT, and its association with PFS and OS. Patients and Methods: Twenty patients with newly diagnosed, symptomatic MM were enrolled. They received four cycles of VRd induction therapy followed by AHCT. Dose modifications of VRd were controlled during the clinical trial. MRD status by MFC was evaluated at the end of induction chemotherapy and at day 100 post-AHCT. The MFC cut-off to determine MRD negativity was defined as 10-4. Outcomes analyzed included MM disease status, PFS and OS. Results: Three cohorts of patients were identified; patients achieving MRD negative status at the end of induction (cohort 1, 50%), those achieving MRD negative status only after AHCT (cohort 2, 15%) and patients never achieving MRD negative status (cohort 3, 35%). All patients achieving MRD negative status at the end of induction remained MRD negative post-AHCT. There were no significant differences in median age, renal function, disease stage, cytogenetic risk and maintenance chemotherapy post-AHCT between cohorts. The table summarizes characteristics of these cohorts. Patients who never achieved MRD negative status after AHCT had significantly shorter PFS (cohort 3) compared with patients who achieved MRD negative status (cohorts 1 and 2, p=0.008) (figure). The median PFS for cohort 3 was 2.64 years and not yet reached for the other cohorts. There were no significant differences in OS. Median follow-up for survivors was 2.53 years (range, 0.73-4.04). Conclusions: In this study, bortezomib-based therapy resulted in half of patients achieving MRD negative status with induction chemotherapy alone. AHCT improved the depth of response with 30% of patients who were MRD positive after induction therapy converting to MRD negativity following AHCT. Achieving a negative MRD state, pre- and at D100 post-AHCT resulted in improved PFS. These findings were independent of molecular cytogenetics or ISS stage. MRD positive status at day 100 post-AHCT is highly predictive of earlier disease progression, and may help identify patients for alternative management approaches. Delay of AHCT may be considered as a potential management option for patients with MRD negative status at the end of induction therapy, as being studied in the IFM DFCI study (NCT01208662). As some patients with MRD positive disease at the end of induction therapy become MRD negative with AHCT, these patients may benefit from AHCT and this population warrants further investigation. Table. Descriptive analysis Cohort 1 MRD -/- (%) (n=10) Cohort 2 MRD +/- (%) (n=3) Cohort 3 MRD +/+ (%) (n=7) Test Statistic Median Age 55 54 60 0.31 ISS Stage III 40 33 14 0.52 DS Stage III 89 67 60 0.14 Median Serum creatinine 0.90 0.60 0.88 0.10 Serum M-spike 2.0 1.9 2.1 0.80 Bone marrow plasma cells 14 44 14 0.18 Cytogenetics 0.37 Standard risk 40 0 57 Intermediate risk 50 67 43 High risk 10 33 0 Figure 1. Kaplan-Meier curve of progression-free survival comparing patients achieving MRD negative disease with MRD positive disease. Figure 1. Kaplan-Meier curve of progression-free survival comparing patients achieving MRD negative disease with MRD positive disease. Disclosures Cornell: Prothena: Research Funding. Jagasia:Takeda Inc: Research Funding.