Parekh, Samir

7503 Background: Optimal initial therapy for mantle cell lymphoma (MCL) remains uncertain. The randomized phase 2 NCTN trial E1411 tested if progression-free survival (PFS) is prolonged by addition of bortezomib (V) (1.6 mg/m2 SC/IV days 1, 8) to bendamustine-rituximab (BVR vs BR) induction and/or by addition of lenalidomide (L) to rituximab (LR vs R) consolidation. Here we report efficacy and toxicity of induction BVR vs BR. Methods: 373 pts, accrued 2012–16, stratified by MIPI and age (≥60) received 1 of 4 arms: A) BR induction x 6 followed by R x 2 yrs, B) BVR followed by R, C) BR followed by LR or D) BVR followed by LR. Eligible pts had untreated MCL, ≥ age 18 (amended from ≥60 when S1106 for < 65 closed), ECOG PS 0-2 and adequate hematologic and organ function. Pts without progressive disease during induction proceeded to consolidation. Primary induction objective was whether adding bortezomib (BVR) (Arms B + D) to BR (Arms A + C) improves PFS, irrespective of consolidation R vs LR. Design of 360 eligible treated pts would provide 93.8% power to detect 10% improvement in 2-yr PFS from 70% hypothesized for BR, corresponding to 37.4% reduction in hazard using stratified log-rank test at 1-sided 10% alpha. Efficacy population was 179 (BVR) and 180 (BR), induction treatment completed in 144 vs 153, progressive disease during induction 6 vs 7 and registration to consolidation 140 vs 145. Results: Baseline demographics did not differ between the groups, with median age 67 (range 42-90) and 13% < 60 yr, 73% men, ECOG PS 0-1 97%, MIPI Low/Med/Hi 37/29/34%. Estimated PFS at 2 yrs 79.6% BVR (95% CI 73.8-85.9) vs 74.5% BR (95% CI 68.2-81.4) (1-sided stratified log-rank p = 0.268). With median PFS follow-up 51 mos, median PFS estimated at 64.1 and 64.0 mos. Overall response rate (ORR) for BVR was 88.9% (CR 65.5%) vs 89.5% (CR 60.5%) BR (z-test 1 sided p = 0.577 for ORR). Treatment related deaths during induction were 2 in BVR (cardiac arrest, hepatitis) and 1 in BR (tumor lysis). Grade ≥ 3 toxicities were 88.1% (163/185) BVR vs 77.5% (145/187) BR. For BVR vs BR grade ≥ 3 neutropenia occurred in 52 vs 39 pts, though febrile neutropenia (7 vs 6), anemia (7 vs 8) and thrombocytopenia (18 vs 16) did not differ. Peripheral neuropathy (PN) grade 2 was 8 sensory for BVR vs 2 sensory/1 motor for BR, while grade 3 PN was 6 sensory/1 motor for BVR vs 0 with BR. The only non-hematologic grade ≥ 3 toxicity in > 5% of pts was rash (9 vs 12 pts). Conclusions: Bortezomib did not significantly improve the primary endpoint of PFS when added to BR as initial MCL therapy. ORR and CR rates at end of induction were also similar. Follow-up continues to assess the entire treatment regimen, including consolidation R vs LR, but the PFS > 5 yrs, high ORR and MRD negativity rate (Smith et al ASH 2019) in this BR-based trial support BR as a platform for MCL induction therapy. Clinical trial information: NCT01415752.

Initial therapy for MCL is effective, but most patients eventually relapse. Validated intermediate biomarkers for MCL are important to provide early assessment of treatment efficacy, prognostic information and potentially guide consolidation. The US-Canadian Intergroup trial E1411 randomly assigned patients (pts) to receive induction with BR ± bortezomib (V), followed by consolidation with R ± L. As a planned correlative, MRD was assessed after cycle 3 (I3), end of induction (EOI) and after 4 cycles of consolidation (C4) by two methods: a research version of clonoSEQ® a next generation sequencing (NGS) MRD assay, (Adaptive Biotechnologies, Seattle, WA) that leverages multiplex PCR followed by NGS to identify and track rearrangements of IgH, V-J, D-J and IgK/L loci as well as translocations in Bcl1/2-IgH, and flow cytometry (FC) (I3 and EOI only) at a central laboratory (Mayo Clinic). While outcomes by treatment arm remain blinded, we report here the results of the MRD assessments by each method and the associated progression free survival (PFS). In E1411, 373 pts, accrued between May 2012 - Sept. 2016, were randomly assigned (stratified by MIPI and age (&lt;/≥60)) to receive BR induction x 6 followed by R for 2 years, BVR followed by R, BR followed by LR or BVR followed by LR. Eligible pts were ≥ age 18 and had untreated MCL, ECOG PS 0-2, and adequate hematologic and organ function. Of the 373 pts, 296 (79%) consented to correlatives. Of these, 255 (86%) had baseline NGS samples, and 214 were analyzable. Excluded were 6 patients that were protocol ineligible, 20 without clinical follow-up; only 7 (2.7%) patients were ineligible due to inability to identify a dominant clone necessary to follow MRD by the NGS method. At baseline pre-treatment, NGS detected a dominant clone in bone marrow (BM) or peripheral blood (PB) in 92%, with only 17 (8%) requiring study of biopsy tissue. Of the 296, 240 had baseline FC data, 9 were protocol exclusions, leaving 231 analyzable. FC detected a non-MCL monoclonal B cell lymphocytosis clone in a small number of cases. While NGS may have higher sensitivity, as FC sensitivity is 10-4, for this analysis we used that cutoff for both NGS and FC. Cohen's Kappa statistic compares concordance between MRD pairs, and p-value is from exact McNemar's test. BR-based initial MCL therapy achieved early MRD negativity (&lt; 10-4) in a high proportion of patients. Analyzing PB at mid-induction (I3): by NGS 89% MRD-, 9% MRD+ and 2% indeterminate, whereas by FC 87% MRD-, 12% MRD+ and 1% indeterminate. Concordance was high with 127 MRD- by both methods, 13 MRD+ by both, and 6 NGS-/FC+ (Kappa Statistic = 0.79, p-value = 0.031). By NGS, of 12 pts MRD+ at I3, 7 became MRD- at EOI, and 4 remained MRD+ (1 indeterminate). Analyzing at EOI: MRD- rates were 91% by NGS analysis of PB (147/161) and 90% in BM (96/107), vs 95% (174/183) by FC in PB. As some were indeterminate, only 7% were MRD+ by NGS in BM, 3% by NGS in PB and 5% by FC. In 88 informative samples with EOI NGS in both BM and PB, concordance was high, with 81 negative in both, 1 positive in both and 6 BM+/PB- (Kappa Statistic = 0.23, p-value = 0.031). Of 101 pts with data at all 3 timepoints, I3, EOI, and C4: 7 were MRD+ at I3, 5 of these were MRD- at EOI, but 2 of these 5 were again MRD+ at C4. Of 2 MRD+ EOI, 1 became MRD- at C4. By FC, of 17 patients MRD+ at I3, 11 (65%) became MRD- at EOI. MRD status correlated with progression-free survival (PFS). Due to the low MRD+ rate at EOI and C4, we focus here on MRD status at I3 (10-4 cutoff for both NGS and FC), using a landmark analysis of 4 months on study. Median PFS (Figure) for pts MRD- at I3 mid-induction was 58.9 months by either NGS or FC, while for those MRD+ by NGS it was 26.9 months, vs 29.9 months MRD+ by FC. Conclusions: Both NGS and FC were feasible to assess MRD status in this multi-center trial. Results of NGS and FC are concordant at the 10-4 cutoff. NGS can be more sensitive when adequate material is available, and analysis of this subgroup is ongoing. The high MRD- rate (≥ 90%) at EOI in this BR-based trial and MRD correlation with PFS supports its use as a platform for MCL trials, although consolidation may confound PFS. Early interim MRD testing at cycle 3 identifies a high-risk population who may benefit from alternative treatment strategies. Analysis by treatment arm with longer follow-up, as well as comparison with centrally reviewed PET/CTs included in this study, will help define the most informative method(s), cutoff values, and timing for assessing degree of response in MCL. Figure. Disclosures Smith: Astra-Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; EUSA: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Parekh:Foundation Medicine Inc.: Consultancy; Celgene Corporation: Research Funding; Karyopharm Inc.: Research Funding. Martin:Sandoz: Consultancy; Karyopharm: Consultancy; Teneobio: Consultancy; Celgene: Consultancy; Janssen: Consultancy; I-MAB: Consultancy. Till:Mustang Bio: Patents & Royalties, Research Funding. Leonard:Gilead: Consultancy; Akcea Therapeutics: Consultancy; Bayer Corporation: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; BeiGene: Consultancy; Celgene: Consultancy; Akcea Therapeutics: Consultancy; Nordic Nanovector: Consultancy; ADC Therapeutics: Consultancy; Sandoz: Consultancy; MorphoSys: Consultancy; Sutro Biopharma: Consultancy; Karyopharm Therapeutics: Consultancy; Karyopharm Therapeutics: Consultancy; Merck: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; Epizyme, Inc: Consultancy; Gilead: Consultancy; AstraZeneca: Consultancy; Epizyme, Inc: Consultancy; Bayer Corporation: Consultancy; Miltenyi: Consultancy; Celgene: Consultancy; ADC Therapeutics: Consultancy; MorphoSys: Consultancy; Sandoz: Consultancy; Miltenyi: Consultancy; AstraZeneca: Consultancy; Nordic Nanovector: Consultancy; Merck: Consultancy; BeiGene: Consultancy; Sutro Biopharma: Consultancy. Friedberg:Bayer: Honoraria, Other: Data & Safety Monitoring Committee; Acerta: Other: Data & Safety Monitoring Committee. Kahl:TG Therapeutics: Consultancy; ADC Therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy; BeiGene: Consultancy.

Abstract Oral mucositis (OM) is a commonly occurring side effect in patients (pts) undergoing AHSCT. Velafermin, recombinant human fibroblast growth factor-20, is under investigation for the prevention of severe OM. Previous studies demonstrated that velafermin at 30 mcg/kg was well tolerated and was effective in reducing the incidence of severe mucositis. The primary objective of this multicenter, randomized, double-blind, placebo controlled study was to confirm safety and efficacy of 30 mcg/kg velafermin for prevention of severe OM incidence (grade 3/4 OM based on the WHO grading system). The secondary objective was to evaluate safety and efficacy of 10 and 60 mcg/kg doses to better define the therapeutic range. Pts were randomized to receive placebo or velafermin at 30, 10 or 60 mcg/kg in a 3:3:1:1 ratio 24–36 hrs after stem cell infusion. Randomization was stratified by study center and OM risk factors identified from the previous placebo controlled study in a similar population including conditioning regimen and body mass index (BMI ≥30). Pts with multiple myeloma or lymphoma (≥18 y.o.) receiving ≥2X106 /kg CD34+ cells following chemotherapy with or without Total Body Irradiation (TBI) were eligible. OM status and safety data were collected for 30 days post treatment while mortality and disease progression were followed for 1 yr. An interim analysis by a data monitoring committee (DMC) was planned to assess safety and efficacy after 50% of pts completed the 30 day treatment period. A total of 390 pts who received melphalan (200 mg/m2) (n=239), BEAM (n=129), TBI (n=15), or other (n=7) were randomized and 384 pts were treated. The study drug was well tolerated in general and no pts discontinued study due to drug-related adverse events. There were 93 serious adverse events (SAEs) in 78 (20%) pts and no drug-related death was reported. Five infusion-related SAEs were reported including vasovagal episode (2), syncope (2), and anaphylactoid reaction (1). All 5 episodes occurred on the day of study drug infusion and resolved on the same day with no sequelae. Based on review of the results from the interim analysis, which included safety and efficacy data from 200 pts, the DMC recommended that the study continue to completion as planned. The last pt has completed the 30 day study period. The un-blinded results of the OM efficacy endpoints from velafermin treated groups or placebo as well as 30-day safety information from all pts will be reported.

Abstract Abstract 1875 Recent experimental evidence suggests that acute myeloid leukemia (AML) originates from hematopoietic stem and progenitor cells (HSPC) following the acquisition of multiple genetic or epigenetic changes that initially give rise to pre-leukemic HSPC (pre-LSC) and then to fully transformed leukemia stem cells (LSC). Relapse continues to be the major cause of death in most subtypes of AML, suggesting that current therapies are largely ineffective in eliminating LSC and pre-LSC. Cellular heterogeneity and the recent observation that LSC are contained within different phenotypic cellular compartments are challenges for the identification of pathways contributing to the initiation and maintenance of AML. To address these challenges we employed a novel strategy of parallel transcriptional analysis of multiple phenotypic HSPC populations from individuals with AML with normal karyotype (N=5), -7/7q- (N=6) and complex karyotype (N=5), including long-term HSC, short-term HSC, and granulocyte-monocyte progenitors (GMP), and comparison to corresponding cell populations from age-matched healthy controls (HC) (N=6). Specifically, we sorted Lin−/CD34+/CD38−/CD90+ (LT-HSC), Lin−/CD34+/CD38−/CD90− (ST-HSC), and Lin−/CD34+/CD38+/CD123+/CD45RA+ (GMP), and hybridized RNA to Affymetrix GeneST 1.0 expression arrays. Differential gene expression was determined within each compartment by direct comparison of AML LT-HSC vs. HC LT-HSC, AML ST-HSC vs. HC ST-HSC, and AML GMP vs. HC GMP. Subsequent intersection of all differentially expressed genes revealed that only a relatively small number of 6 to 11 genes were consistently dysregulated in all examined leukemic stem and progenitor cell compartments. Interleukin 1 receptor accessory protein (IL1RAP) was one of the most significantly upregulated genes in LT-HSC, ST-HSC, and GMP in all examined subtypes of AML. IL1RAP is a transmembrane protein required for signaling through several receptors of the IL1 family, including IL-1R1 and ST2. We detected significant overexpression of IL1RAP protein on HSC and progenitor cells of AML patients. Interestingly, CD34+/Lin+ precursor cells showed only a marginal increase of IL1RAP at the protein level in AML, underscoring the importance of purifying HSPC with stringent lineage depletion. We performed fluorescence in situ hybridization in sorted IL1RAP+ and IL1RAP− cells from -7 AML. We observed that the -7 clone was restricted to IL1RAP+ cells, while IL1RAP- cells did not display monosomy 7, demonstrating that IL1RAP overexpression is a distinguishing feature of the cells of the -7 clone. Patients with normal karyotype AML showed a wider range of IL1RAP expression levels; some were as high as in -7 AML and others were as low as in HC. We asked whether IL1RAP expression levels were associated with known clinical or molecular parameters. We analyzed two published datasets of patients with normal karyotype AML (Metzeler, Blood. 2008;112:4193–4201; Tomasson, Blood. 2008;111:4797–4808). Patients with high IL1RAP levels showed inferior overall survival than patients with lower IL1RAP (p=2.2×10−7; median survival: 7.82 mo. for IL1RAP high, 20 mo. for IL1RAP low). Multivariate analysis using a Cox regression model showed that high IL1RAP status was an independent prognostic factor (p=0.002), and even stronger than FLT3 mutation status (p=0.006). In addition, we analyzed data from 183 patients with MDS and found IL1RAP expression to be specifically elevated in cases with RAEB-2, suggesting a role of IL1RAP in MDS and in the progression to AML. Downregulation of IL1RAP protein expression in 4 AML cell lines (THP1, OCI-AML3, HL60, HEL) led to a significant 45–98% decrease in clonogenic growth and increased apoptosis in vitro. To assess the effects of IL1RAP downregulation in vivo, we performed xenotransplants into immunodeficient NOD/SCID/IL2Rg-null mice. THP-1 AML cells showed a 92% reduced proliferation and infiltration of hematopoietic organs upon IL1RAP knockdown in comparison to a non-silencing control in vivo. Genetic studies to assess the role of IL1RAP in the initiation and maintenance of AML in an IL1RAP−/− mouse model are currently ongoing. In summary, our study provides a map of consistently dysregulated transcripts across multiple fractionated stem and progenitor cell types from patients with AML, and identifies IL1RAP as a putative new therapeutic and prognostic target in stem cells in AML and MDS. Disclosures: No relevant conflicts of interest to declare.

Epigenetic drugs can overcome resistance to monoclonal antibodies in T-PLL and activate therapeutic targets for antibody-drug conjugates.

Abstract Despite the established use of poly-chemotherapy, relapse continues to be the most common cause of death in AML and MDS and cure rates remain below 20%. AML/MDS arise following the accumulation of stepwise genetic and epigenetic changes in hematopoietic stem and progenitor cells (HSPC). Utilizing a novel strategy of parallel transcriptional analysis of sorted HSPC populations in distinct subtypes of AML, we compared the gene expression in AML HSPC with identical compartments from age-matched healthy controls and identified Interleukin 1 receptor accessory protein (IL1RAP) as one of the most significantly upregulated genes in HSPC in all examined subtypes of AML. Fluorescence in situ hybridization of sorted IL1RAP+ and IL1RAP- cells from patients with monosomy 7 AML (-7) indicated that the aberrant clone was restricted to IL1RAP+ cells, demonstrating that IL1RAP overexpression is a distinguishing feature of the -7 clone. Multivariate analysis of a large cohort of patients with normal karyotype AML showed that patients with high IL1RAP levels had inferior overall survival than patients with lower IL1RAP levels, suggesting an independent prognostic value for this molecule in AML. IL1RAP expression levels in MDS were found elevated on stem cells of patients with high risk disease, proposing a role of IL1RAP in higher risk MDS and progression to AML. Downregulation of IL1RAP expression by lentivirally expressed shRNAs decreased clonogenicity in cell lines and AML/MDS primary patient samples, induced apoptosis of AML cells, and reduced proliferation of AML cells and infiltration of hematopoietic organs in vivo. IL1RAP is a transmembrane protein required for signaling through several receptors of the IL1 family. Downregulation of IL1RAP expression in AML cells led to phosphorylation changes in several kinases and their substrates suggesting participation of IL1RAP in multiple signaling pathways and highlighting its potential as therapeutic target. We investigated whether inhibition of IL1RAP with pharmacological compounds is feasible and effective. Antibody-mediated inhibition of IL1RAP led to inhibition of AML cell growth in vitro. In addition, we designed peptides to interfere with IL1RAP-receptor interactions which lead to inhibition of AML cell growth. Both types of agents are being further tested and optimized. In summary, our study reveals IL1RAP as aberrantly expressed on HSPC of AML and high-risk MDS patients. Inhibition of IL1RAP is feasible and functionally effective, and thus has the potential to lead to novel therapies specifically directed at such stem cells. Beyond IL1RAP, our study provides a map of dysregulated transcripts in HSPC from patients with AML, which may offer further opportunities for therapeutic intervention. The strategy of comparative analysis of sorted stem and progenitor cells in cancer versus healthy controls may be applicable to other type of cancers with a suspected stem cell origin, and instrumental for the identification of targets for stem cell-directed therapy. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C225. Citation Format: Laura Barreyro, Kelly Mitchell, Britta Will, Boris Bartholdy, Li Zhou, Tihomira Todorova, Robert Stanley, Susana Ben-Neriah, Cristina Montagna, Samir Parekh, Andrea Pellagatti, Jacqueline Boultwood, Elisabeth Paietta, Rhett Ketterling, Larry Cripe, Hugo Fernandez, Peter Greenberg, Jacob Rowe, Martin Tallman, Christian Steidl, Constantine Mitsiades, Amit Verma, Ulrich Steidl. IL1RAP as functionally relevant target for stem-cell directed therapy in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C225.

AbstractCellular and interpatient heterogeneity and the involvement of different stem and progenitor compartments in leukemogenesis are challenges for the identification of common pathways contributing to the initiation and maintenance of acute myeloid leukemia (AML). Here we used a strategy of parallel transcriptional analysis of phenotypic long-term hematopoietic stem cells (HSCs), short-term HSCs, and granulocyte-monocyte progenitors from individuals with high-risk (−7/7q−) AML and compared them with the corresponding cell populations from healthy controls. This analysis revealed dysregulated expression of 11 genes, including IL-1 receptor accessory protein (IL1RAP), in all leukemic stem and progenitor cell compartments. IL1RAP protein was found to be overexpressed on the surface of HSCs of AML patients, and marked cells with the −7/7q− anomaly. IL1RAP was also overexpressed on HSCs of patients with normal karyotype AML and high-risk myelodysplastic syndrome, suggesting a pervasive role in different disease subtypes. High IL1RAP expression was independently associated with poor overall survival in 3 independent cohorts of AML patients (P = 2.2 × 10−7). Knockdown of IL1RAP decreased clonogenicity and increased cell death of AML cells. Our study identified genes dysregulated in stem and progenitor cells in −7/7q− AML, and suggests that IL1RAP may be a promising therapeutic and prognostic target in AML and high-risk myelodysplastic syndrome.