Jensen, Jeffrey L.

Abstract Purpose: Mutations in hematopoietic progenitor cells accumulate with age leading to clonal expansion, termed clonal hematopoiesis (CH). CH in the general population is associated with hematopoietic neoplasms and reduced overall survival (OS), predominantly through cardiovascular adverse events (CVAE). Because androgen receptor pathway inhibitors (ARPI) used in metastatic castration-resistant prostate cancer (mCRPC) are also associated with CVAEs and because CH negatively impacted survival in an advanced solid tumor cohort, we hypothesized that CH in mCRPC may be associated with increased CVAEs and inferior survival. Experimental Design: A targeted DNA sequencing panel captured common CH mutations in pretreatment blood samples from 957 patients enrolled in Alliance A031201: a randomized trial of enzalutamide ± abiraterone/prednisone in the first-line mCRPC setting. The primary outcome was the impact of CH on OS; the secondary outcomes were progression-free survival (PFS) and CVAEs. Results: Baseline comorbidities were similar by CH status. No differences in OS/progression-free survival were detected regardless of treatment arm or the variant allele frequency threshold used to define CH [primary: 2% (normal-CH, N-CH); exploratory: 0.5% (low-CH) and 10% (high-CH, H-CH)]. Patients with H-CH (7.2%) and TET2-mutated N-CH (6.0%) had greater odds of any CVAE (14.5% vs. 4.0%; P = 0.0004 and 12.3% vs. 4.2%; P = 0.010, respectively). More major CVAEs were observed in patients with H-CH (5.8% vs. 1.9%; P = 0.042) and N-CH (3.4% vs. 1.8%; P = 0.147). Conclusions: CH did not affect survival in patients with mCRPC treated with ARPIs in A031201. H-CH and TET2-mutated CH were associated with more CVAEs. These findings inform the risk/benefit discussion about ARPIs in mCRPC.

7533 Background: Maintenance treatment (rx) with lenalidomide (R) improves overall survival (OS) in multiple myeloma (MM). We report a retrospective cohort of patients (pts) with second primary B-cell acute lymphoblastic leukemia (ALL) diagnosed after R-rx for MM. Methods: We included pts who were exposed to at least 1 yr of R for MM rx prior to ALL dx. After approval by institutional review board, data were collected by chart review at participating centers using Redcap. OS was the primary endpoint. We used BlueSky statistics v10.3.1 for analysis. Results: Analysis included 33 ALL pts diagnosed from 2014-2022 at 7 sites. 52% pts were female. Median follow up was 9.6 yrs (95%CI,7.6-11.8) from MM dx and 3.2 yrs (CI, 2.1-4.7) from ALL dx. Pt characteristics at MM dx are given in Table. Induction rx included: proteasome inhibitor (PI) +immunomodulatory drug (IMiD) (43%), PI+alkylator (24%), IMiD (18%) & others (15%). 50% pts received autologous stem cell transplantation (ASCT). Median OS from MM dx was 11.2 yrs (CI, 8.9-NR). Time from MM dx and initial R rx to ALL dx were 5.0 yrs (range, 2.4-18.5) and 4.4 yrs (2.2-10.6) respectively. Median duration of R exposure before ALL dx was 3.8 yrs (1.6-10.4). Table shows characteristics of pts at B-ALL dx and genetic classification based on karyotyping (n=30), ALL FISH (n=28), chromosomal microarray (n=5) and next-generation sequencing (n=5). 31 pts received ALL-directed rx while 1 pt was initially managed with close observation as the pt attained CR on stopping R ( Lakshman et al; ASH 2019 ). Rx was unknown in 1 pt. Initial rx included: hyper-CVAD+/- rituximab- 49%, pediatric inspired protocols-18%, reduced intensity rx for frail pts- 21% and others- 12%. Response to first line rx were: CR- 56%, CRi- 28%, induction failure- 16%. 32% pts attained measurable residual disease (MRD) negativity. 48% pts underwent SCT for ALL. 14 pts died during follow up. 3-yr OS from ALL-dx was 50% (CI, 33%-76%). 3 pts required rx for MM after ALL diagnosis (2 had allo-SCT for ALL before MM relapse). Conclusions: Most pts had standard risk MM and were exposed to R for several years prior to dx of B-ALL, characterized by high incidence of hypodiploid karyotype; IKZF1 loss and TP53 deletions/mutations were detected in a subset of pts.MRD-adapted timely discontinuation of R in standard risk MM may decrease risk of second primary ALL. [Table: see text]

5021 Background: Somatic mutations in hematopoietic progenitor cells accumulate with age leading to clonal expansion in a process called clonal hematopoiesis (CH). CH increases the risk of developing myeloid neoplasms and shortens overall survival (OS), primarily linked to increased cardiovascular (CV) mortality. The impact of CH in metastatic solid cancers has been conflicting, with shorter OS in a broad cancer cohort but prolonged OS in metastatic colorectal cancer, which may be influenced by prior cytotoxic therapy that can promote emergence of CH. As AR pathway inhibitors (ARPIs) are associated with CV adverse events (AE), exploring the impact of CH in patients (pts) with mCRPC is of interest. Methods: A 9 gene targeted DNA sequencing panel designed to capture common CH mutations ( DNMT3A, TET2, ASXL1, PPM1D, TP53, CHEK2, SRSF2, SF3B1, JAK2) was applied to pre-treatment peripheral blood samples of 957 pts enrolled in the Alliance A031201 phase 3 trial of enzalutamide versus enzalutamide plus abiraterone/prednisone in the first line mCRPC setting. No difference in OS was found between treatment arms. The primary endpoint was the impact of CH on OS; secondary and exploratory endpoints included progression-free survival (PFS) and associations with baseline comorbidities and AEs (hematologic and CV). Cox proportional-hazards and logit models were adjusted for treatment arm, age, and radiation therapy (RT). Results: CH was common with 57% of pts having low CH (VAF>0.5% in 1+ mutation, L-CH), 24% having standard CH (VAF>2%, CH), and 7% having high CH (VAF>10%, H-CH). 4% of pts had 2+ CH mutations and 1% had 3+ mutations. Patients with CH were older (73.1 vs 70.2) and had higher rates of prior RT (58.4% vs 55.7%) and prior chemotherapy (3.9% vs 2.2%). No differences in OS were detected in pts with L-CH, CH, or H-CH. Similarly, no differences in PFS or baseline CV comorbidities were seen in any CH group. Pts with H-CH and TET2-mutated CH had statistically higher odds of any CV event (adjusted p=0.0004 and p=0.010, respectively) There was also a difference in the occurrence of major adverse CV events (MACE) by H-CH status (5.8% vs. 1.9%, adjusted p=0.042), while there was no difference seen for CH (3.4% vs 1.8%, adjusted p=0.147). Regarding hematologic AEs, one pt with a TP53 mutation (VAF 0.94%) developed myelodysplastic syndrome. Conclusions: CH did not affect OS or PFS in pts with mCRPC treated with ARPIs in the A031201 trial. However, CH with VAF>10% and TET2-mutated CH were associated with an increased rate of all CV AEs, suggesting an additive effect of ARPI therapy and CH on adverse CV outcomes. Confirmatory studies are warranted to assess whether CH should be considered in the risk-benefit discussion for pts receiving ARPIs.

Abstract NRAS Q61 mutations are prevalent in advanced/relapsed multiple myeloma (MM) and correlate with poor patient outcomes. Thus, we generated a novel MM model by conditionally activating expression of endogenous NrasQ61R and an MYC transgene in germinal center (GC) B cells (VQ mice). VQ mice developed a highly malignant MM characterized by a high proliferation index, hyperactivation of extracellular signal-regulated kinase and AKT signaling, impaired hematopoiesis, widespread extramedullary disease, bone lesions, kidney abnormalities, preserved programmed cell death protein 1 and T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif domain immune-checkpoint pathways, and expression of human high-risk MM gene signatures. VQ MM mice recapitulate most of the biological and clinical features of human advanced/high-risk MM. These MM phenotypes are serially transplantable in syngeneic recipients. Two MM cell lines were also derived to facilitate future genetic manipulations. Combination therapies based on MEK inhibition significantly prolonged the survival of VQ mice with advanced-stage MM. Our study provides a strong rationale to develop MEK inhibition–based therapies for treating advanced/relapsed MM.

Abstract Myeloma remains a virtually incurable malignancy. The inevitable evolution of multidrug-resistant clones and widespread clonal heterogeneity limit the potential of traditional and novel therapies to eliminate minimal residual disease (MRD), a reliable harbinger of relapse. Here, we show potent anti-myeloma activity of macrophage-activating immunotherapy (αCD40+CpG) that resulted in prolongation of progression-free survival (PFS) and overall survival (OS) in an immunocompetent, preclinically validated, transplant-based model of multidrug-resistant, relapsed/refractory myeloma (t-Vκ*MYC). αCD40+CpG was effective in vivo in the absence of cytolytic natural killer, T, or B cells and resulted in expansion of M1-polarized (cytolytic/tumoricidal) macrophages in the bone marrow. Moreover, we show that concurrent loss/inhibition of Tpl2 kinase (Cot, Map3k8), a MAP3K that is recruited to activated CD40 complex and regulates macrophage activation/cytokine production, potentiated direct, ex vivo anti-myeloma tumoricidal activity of αCD40+CpG–activated macrophages, promoted production of antitumor cytokine IL12 in vitro and in vivo, and synergized with αCD40+CpG to further prolong PFS and OS in vivo. Our results support the combination of αCD40-based macrophage activation and TPL2 inhibition for myeloma immunotherapy. We propose that αCD40-mediated activation of innate antitumor immunity may be a promising approach to control/eradicate MRD following cytoreduction with traditional or novel anti-myeloma therapies. Cancer Immunol Res; 3(8); 881–90. ©2015 AACR.

Abstract Early-stage myeloma tumor cells are critically dependent on paracrine cytokine support originating from their bone marrow microenvironment whereas advanced-stage myeloma tumor cells may elaborate autocrine cytokine production mechanisms and/or cell-autonomous mutations in critical downstream signaling pathways (e.g., NFκB pathway). However, the molecular mechanisms underpinning the paracrine network in myeloma are unclear. The pro-inflammatory cytokine IL-1β has emerged as a major link between inflammation and cancer and has been validated as a therapeutic target in high-risk monoclonal gammopathy, the precursor to myeloma, as well as early-stage myeloma. To determine the source of IL-1β production in early-stage myeloma we analyzed paired purified cell fractions obtained from each of 5 patients at diagnosis: CD138+ tumor cells, CD14+ bone marrow-resident monocyte/macrophages as well as bone marrow-derived stromal/mesenchymal cells (BM-MSC). We found that in all cases, monocytes/macrophages were the predominant IL-1β synthesizer cell type in the myeloma microenvironment. Cytokine production by activated macrophages is controlled by the MAP3 kinase, TPL2 (Cot, MAP3K8). We have previously detected constitutive activation of TPL2-regulated signaling pathways in human myeloma-associated macrophages but its precise functional consequences have been unclear. To dissect the relevant mechanisms, we ablated Tpl2 in the genetically-engineered myeloma in vivo model, Vκ*MYC. Vκ*MYC animals activate MYC sporadically in B lymphocytes participating in germinal center reactions and develop a disease analogous to human multiple myeloma with production of paraprotein (monoclonal immunoglobulin), plasma cell infiltration of the bone marrow as well as end-organ damage (“myeloma kidney”, osteolytic lesions). Vκ*MYC+/Tpl2-null animals developed myeloma with a significantly prolonged latency and the disease burden was lower at all timepoints tested compared to controls. Analysis of monocytic cells from myeloma lesions showed that loss of Tpl2 did not result in macrophage repolarization to an unopposed M1 (tumoricidal/cytotoxic) phenotype. Instead, Tpl2-null myeloma-associated monocytes/macrophages exhibited severe defects in production of inflammatory cytokines, predominantly IL-1β, but also IL-6. Tpl2 loss did not have discernible impacts on tumor cell-autonomous growth and survival. Our results suggest that monocytes/macrophages and TPL2 kinase activity play a central role in orchestrating the inflammatory milieu of the myeloma niche. Disruption of the myeloma cytokine network through pharmacologic TPL2 kinase inhibition could provide novel therapeutic opportunity by interfering with the co-ordinate regulation of key pro-myeloma inflammatory cytokines through a targeted approach. Citation Format: Chelsea Hope, Samuel J. Ollar, Erika Heninger, Jeffrey L. Jensen, Ellen Hebron, Jaehyup Kim, Ioanna Maroulakou, Shigeki Miyamoto, Natalie Callander, Peiman Hematti, Marta Chesi, P. Leif Bergsagel, Fotis Asimakopoulos. TPL2 kinase regulates the inflammatory milieu of the myeloma niche. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1169. doi:10.1158/1538-7445.AM2014-1169

Key PointsWe describe a novel, druggable pathway that controls myeloma growth through macrophages in the myeloma microenvironment. Macrophages are dominant orchestrators of the inflammatory milieu of the myeloma niche.