Abstract Targeted therapies can induce responses in patients with relapsed/refractory T-cell lymphoma (R/R TCL) but are not curative. Genetic mutations associated with epigenetic and transcriptional dysregulation are common in many TCL subtypes, and drugs that modulate the epigenome and that target transcriptional regulators have synergistic activity in TCL. We hypothesized that fixed duration treatment with multiagent combinations of these drugs could produce deep responses leading to durable remissions. In a phase 1 trial, we tested escalating doses of lenalidomide added to romidepsin, azacitidine, and dexamethasone (RAdR) for patients with R/R TCL. The primary objective was to identify the maximum tolerated dose (MTD) of lenalidomide that could safely be used in RAdR. Secondary end points included response rate, survival, and markers of immune activation. Twenty-six patients enrolled and 21 were evaluable for response. Adverse events were predominantly gastrointestinal and hematologic. Grade 3/4 thrombocytopenia and neutropenia occurred in 19% and 21% of cycles, respectively. The MTD of lenalidomide was 20 mg. Among 9 patients treated at the MTD the objective response rate was 89% and complete response rate 22%. At 1 year, the estimated rate of progression-free survival was 14% and overall survival was 66%. Cell line models of anaplastic large cell lymphoma were interrogated to explore the activity of drug combinations in responding genetic subtypes. RAdR demonstrated activity in patients with highly refractory TCL but did not induce durable responses. This novel combination effectively bridged some patients with refractory TCL to consolidation such as allogeneic transplantation. This trial was registered at www.ClinicalTrials.gov as NCT04447027.

Background:Follicular lymphoma (FL) shows marked heterogeneity in clinical course including spontaneous regression and histologic transformation (HT). Watchful waiting (W&W) is routinely employed, but monitoring is not standardized. A subset of pts require treatment early after diagnosis, but biologic basis is unclear. Improved classifiers and monitoring tools are needed. Circulating tumor DNA (ctDNA) is a highly tumor-specific biomarker that is prognostic in aggressive B-cell lymphomas. We previously showed that ctDNA in plasma can be identified in >90% FL pts with next-generation sequencing of Ig heavy- and light-chain loci. Here, we present updated results from serial ctDNA monitoring of pts on a prospective clinical trial [NCT03190928]. Methods: Adult pts with grade 1-3A FL were eligible if evaluable disease, no HT, and no prior systemic therapy. Pts underwent W&W until they met uniform protocol-defined treatment criteria and then monitored until 2nd line therapy. Baseline testing included plasma, CT and PET, and biopsy. Clinic visits were every 4m for 2y, every 6m in years 3-5, then annually with CT scans every other clinic visit. PET scans were repeated at 2y, or at suspected disease progression. Cell-stabilizing tubes (plasma) and PBMCs were drawn at each visit. Analysis of ctDNA was performed using the research version of clonoSEQ blinded to clinical outcomes. The primary endpoint was progression requiring treatment within 2 years of enrollment. Pts who required treatment in first 2 years were labeled early progressors and those without treatment were labeled non-progressors. Results: 78 pts enrolled between July 2017 and Aug 2021, of which 77 had baseline plasma samples. Of 58 pts with available FFPE tumor biopsies, all (100%) had ≥1 dominant clonotype(s) identified from tumor. Of 19 pts without FFPE, ≥1 dominant clonotype was identified from plasma in 7 (37%). These 65 pts with trackable clonotype(s) comprised the study population. Median age of the study population was 57y (range 24-84), including 12 (18%) low-risk, 25 (39%) intermediate-risk, and 28 (43%) high-risk by FLIPI. Baseline ctDNA was detectable in 60 (92%) pts with median (interquartile range [IQR]) level of 34 (6-114) lymphoma molecules per mL. Four (80%) pts with undetectable ctDNA at baseline had stage 1-2 disease. Baseline ctDNA levels correlated with both FLIPI (p<0.01) and total metabolic tumor volume (TMTV) on PET (p<0.001). Three pts were unevaluable for progression at 2y due to non-progression events including a second malignancy, sudden death, and hemolytic anemia requiring rituximab. Thirty-three (53%) pts were early progressors and 29 (47%) were non-progressors at 2y. Median time to treatment (TTT) was 20m (95% CI, 10-68). Early progressors had median (IQR) baseline ctDNA level of 38.2 (13-189.4) compared to 18.7 (1.2-56.8) lymphoma molecules per mL for non-progressors. Pts with >median baseline ctDNA levels had median TTT of 9.7m (95% CI, 2.8-NE) compared to 37m (95% CI, 17-NE) for pts with Median (IQR) baseline TMTV was 138 (39-388) cm3. Pts with >median baseline TMTV had median TTT of 5.3m (95% CI, 2.1-28) compared to 54m (95% CI, 26-NE) for pts with Ten (15%) pts had HT. Neither baseline ctDNA levels (p=0.85) nor TMTV (p=0.65) were associated with increased risk of subsequent HT. Twenty-three (39%) pts had spontaneous regression of tumor lesions by ≥25% on CT. Lower baseline ctDNA levels (p=0.02) and TMTV (p<0.01) were associated with subsequent spontaneous regression. Twenty pts with spontaneous regression had serial samples and 13 (65%) had decrease in ctDNA levels corresponding to CTs. Conclusions: Circulating tumor DNA is detectable in baseline plasma of >90% pts with untreated FL. Quantitative ctDNA levels correlate with both FLIPI and TMTV and are associated with earlier need for treatment. Serial ctDNA monitoring shows fluctuating levels that correlate with tumor burden on CT which provides a non-invasive method to monitor disease. Baseline ctDNA levels and TMTV do not predict future histologic transformation.

Context Targeted therapies appear promising in R/R TCM. We hypothesized that the multi-targeted therapy regimen RAdR would be safe and effective in R/R TCM. Methods We tested escalating doses of lenalidomide (5-20 mg) with romidepsin, azacitidine, and dexamethasone in a phase 1 study. Patients received a 7-day window of lenalidomide followed by 6 cycles of romidepsin (12 mg/m2; D1 and D10), azacitidine (300 mg; D1-10), dexamethasone (40 mg; D1 and D10), and lenalidomide (5-20 mg; D1-10) in up to six 21-day cycles. The primary endpoint was maximum tolerated dose (MTD) of lenalidomide, and the primary objective was safety of the regimen. A 3+3 design was used with an additional 9 patients treated at the MTD. Results Twenty-six patients were enrolled with a median age of 61 years (range, 28-80); 8 (31%) had PTCL-NOS; 6 (23%) MF; 5 (19%) AITL; and 4 (15%) ATLL. Median prior lines of therapy were 2 (range, 1-8); and 2 patients had received prior allogeneic SCT. The most frequent grade ≥3 AEs were infection (16%) and hypokalemia (16%). Hematologic grade ³3 AEs, per cycle, included neutropenia (24%), anemia (12%), and thrombocytopenia (12%). Two DLTs were observed, grade 4 thrombocytopenia at DL1 and grade 3 abdominal pain at DL2. The MTD of lenalidomide was 20 mg. In evaluable patients (n=21), ORR was 66% and CR rate was 14% after a median follow-up of 19 months. Median PFS and OS were 4 months and not reached, respectively. Two patients (PTCL-NOS and MF) completed the planned 6 cycles and remain in remission without consolidation beyond 30 months. Five patients were successfully bridged to SCT, all of whom remain alive and without progression. In patients treated at the MTD (n=9), the ORR was 89% and CR rate was 22%. Conclusions The multi-targeted therapy regimen RAdR is safe and can achieve CR after fixed duration in patients with R/R TCM. Toxicity is predominantly gastrointestinal and hematologic. Most patients do not achieve durable CR with RAdR alone, but it may be an effective bridging therapy to consolidation. Acknowledgement This study was supported by the Intramural Research Program of the NIH (NCT04447027).

Introduction Recombinant human interleukin-15 (rhIL-15) is an immunotherapeutic which enhances NK-cells to augment the antibody directed cellular cytotoxicity (ADCC) of monoclonal antibodies. Mogamulizumab is a CCR4 directed monoclonal antibodies that exerts cytotoxicity through ADCC and depletes regulatory T-cells within the tumor microenvironment. Methods We conducted a phase 1 clinical trial of rhIL-15 combined with mogamulizumab. Patients with relapsed or refractory adult T-cell leukemia/lymphoma (ATLL), mycosis fungoides (MF) and Sezary syndrome (SS) received fixed dose mogamulizumab combined with escalating doses of rhIL-15 to identify the maximum tolerated dose (MTD). Results Six patients were enrolled, 4 with ATLL and 2 with MF/SS. The most common adverse events were rash, infection and fever (67%, in all). Two patients (33%) had grade 4 acute kidney injury and 25% of cycles had grade ≥3 anemia. The MTD was dose level 1. One patient with ATLL had a partial response despite receiving only 4 cycles due to grade 4 myositis. Circulating NK cells were increased in all patients during the first cycle and a rapid reduction in tumor cells within the peripheral circulation was noted. Ex vivo assessment demonstrated increased NK cell activation and increased cell lysis in the presence of monoclonal antibodies after only 5 days. Discussion Our small study suggests that rhIL-15 combined with mogamulizumab leads to effector NK cell activation and regulatory T-cell depletion but has an unfavorable safety profile. Future development of combinations of immunotherapy that target the microenvironment in relapsed or refractory T-cell lymphomas remain rational. NCT04185220

Abstract Romidepsin, azacitidine and lenalidomide are all active in T-cell malignancies (TCM) demonstrating single agent objective response rates (ORR) of 20 to 30% (Coiffier 2012; Morschhauser 2013; Dupuis 2022). Combinations of these targeted agents improves the rates of complete response (CR) but have significant toxicity due to indefinite schedules. We hypothesized that use of a multi-targeted therapy regimen such as RAdR given in fixed duration cycles would be safe and effective. We tested escalating doses of lenalidomide (5-20mg) with fixed doses of romidepsin, azacitidine and dexamethasone in a phase 1 study. Patients (pts) first received a 7-day window of lenalidomide for cytokine correlative research followed by six cycles of romidepsin (12mg/m2; days 1 and 10), azacitidine (300mg; days 1-10), dexamethasone (40mg; days 1 and 10), and lenalidomide (5-20mg; days 1-10) in 21-day cycles for up to 6 cycles. The primary endpoint was the maximum tolerated dose (MTD) of lenalidomide and the primary objective was the overall safety of the regimen. A 3+3 design was used with an additional 9 pts treated at the MTD. 26 pts were enrolled with a median age of 61 years (range, 28-80) including 31% over 65. Eight (31%) pts had PTCL, NOS, 6 (23%) had mycosis fungoides (MF), 5 (19%) had angioimmunoblastic T-cell lymphoma, and 4 (15%) ATLL. Median prior lines of therapy were 2 (range, 1-8), 31% had received >3 prior lines and 2 patients had received prior allogeneic transplantation. The median number of cycles was 4 (range, <1-6). The most frequent reasons for stopping therapy were progressive disease (38%), completion of planned therapy (27%) and adverse events (23%). The most frequent grade 1-2 non-hematologic adverse events were vomiting (52%), diarrhea (48%) and dysgeusia (48%), and AE grade 3+ included infection (16%) and hypokalemia (16%). Grade 3+ neutropenia occurred in 24% of cycles and both grade 3+ anemia and thrombocytopenia in 12% of cycles. Two DLTs were observed, grade 4 thrombocytopenia at dose level 1 and grade 3 abdominal pain at dose level 2. The MTD of lenalidomide was determined to be 20mg. In evaluable pts (N=21) the ORR was 66% and CR rate was 14%. After a median follow-up of 23 months. Median progression free survival (PFS) and overall survival (OS) were 4 months and not reached, respectively. 2-year OS was 53%. Two pts (PTCL, NOS and MF) completed the planned 6 cycles of therapy and remain in remission without consolidation at 30 months. Five pts were successfully bridged to SCT, all of whom remain alive and without progression. In pts treated at the MTD, the ORR was 89% and the CR rate was 22%. The multi-targeted therapy regimen RAdR is safe and can achieve CR after fixed duration in patients with relapsed refractory TCM. Toxicity is predominantly gastrointestinal and hematologic. Most patients do not achieve durable CR with RAdR alone, but it may be effective bridging therapy to consolidation. This study was supported by the Intramural Research Program of the NIH and was registered at Clinicaltrials.gov [NCT04447027]. Citation Format: Max Gordon, Milos Miljkovic, Samuel Ng, Rahul Lakhotia, Christopher Melani, Kevin Conlon, James Phelan, Bonita Bryant, Stefania Pittaluga, Elaine Jaffe, Louis Staudt, Wyndham Wilson, Mark Roschewski. A phase 1 study of romidepsin, azacitidine, dexamethasone, and lenalidomide (RAdR) for relapsed/refractory T-cell malignancies [abstract]. In: Proceedings of the Fourth AACR International Meeting on Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2024 Jun 19-22; Philadelphia, PA. Philadelphia (PA): AACR; Blood Cancer Discov 2024;5(3_Suppl):Abstract nr PO-007.

Interleukin-15 (IL-15) monotherapy substantially increases the number and activity of natural killer (NK) cells and CD8+ T cells but has not produced clinical responses. In a xenograft mouse model, IL-15 enhanced the NK cell-mediated antibody-dependent cell cytotoxicity (ADCC) of the anti-CD52 antibody alemtuzumab and led to significantly more durable responses than alemtuzumab alone. To evaluate whether IL-15 potentiates ADCC in humans, we conducted a phase 1 single-center study of recombinant human IL-15 and alemtuzumab in patients with CD52-positive mature T-cell malignances. We gave IL-15 subcutaneously 5 days per week for 2 weeks in a 3 + 3 dose escalation scheme (at 0.5, 1, and 2 mu g/kg), followed by standard 3 times weekly alemtuzumab IV for 4 weeks. There were no dose-limiting toxicities or severe adverse events attributable to IL-15 in the 11 patients treated. The most common adverse events were lymphopenia (100%), alemtuzumab-related infusion reactions (90%), anemia (90%), and neutropenia (72%). There were 3 partial and 2 complete responses, with an overall response rate of 45% and median duration of response 6 months. Immediately after 10 days of IL-15, there was a median 7.2-fold increase in NK cells and 2.5-fold increase in circulating CD8+ T cells, whereas the number of circulating leukemic cells decreased by a median 38% across all dose levels. Treatment with IL-15 was associated with increased expression of NKp46 and NKG2D, markers of NK-cell activation, and increased ex vivo ADCC activity of NK cells, whereas inhibitory receptors PD1 and Tim3 were decreased. This trial was registered at www.clinicaltrials.gov as #NCT02689453.

Differentiation from CD56 bright to CD56 dim /CD94 high to CD56 dim /CD94 low NK cells is accompanied by increasing requirements for IL-15 to induce their proliferation. Various NK cell subsets were sorted from PBMCs of normal donors, CFSE-labeled, cultured for 7 days, and their CFSE dilu- tion as a measure of proliferation was determined by FACS.

Naïve T cells and regulatory T cells, when purified, do not proliferate to the γ c -cytokines IL-2, IL-7, or IL-15, despite their expression of cognate cytokine receptors. Dendritic cells (DCs) enabled the T cell proliferation to these cytokines, through cell-to-cell contact, but independent of T cell receptor stimulation. This effect lasted after separation of T cells from DCs, enabling enhanced proliferation of the T cells in DC-depleted hosts. We propose calling this a “preconditioning effect”. Interestingly, IL-2 alone was sufficient to induce phosphorylation and nuclear translocation of STAT5 in T cells, but could not activate MAPK and AKT pathways and failed to induce transcription of IL-2 target genes. “Preconditioning” was necessary to activate these two pathways and induced weak Ca 2+ mobilization independent of calcium release-activated channels. When preconditioning was combined with IL-2, full activation of downstream mTOR, 4E-BP1 hyperphosphorylation, and prolonged S6 phosphorylation occurred. Collectively, accessory cells provide T cell preconditioning, a unique activation mechanism, controlling cytokine-mediated proliferation of T cells.

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive T-cell malignancy with a poor prognosis with current therapy. Here we report genome-wide CRISPR-Cas9 screening of ATLL models, which identified CDK6, CCND2, BATF3, JUNB, STAT3, and IL10RB as genes that are essential for the proliferation and/or survival of ATLL cells. As a single agent, the CDK6 inhibitor palbociclib induced cell cycle arrest and apoptosis in ATLL models with wild-type TP53. ATLL models that had inactivated TP53 genetically were relatively resistant to palbociclib owing to compensatory CDK2 activity, and this resistance could be reversed by APR-246, a small molecule activator of mutant TP53. The CRISPR-Cas9 screen further highlighted the dependence of ATLL cells on mTORC1 signaling. Treatment of ATLL cells with palbociclib in combination with mTORC1 inhibitors was synergistically toxic irrespective of the TP53 status. This work defines CDK6 as a novel therapeutic target for ATLL and supports the clinical evaluation of palbociclib in combination with mTORC1 inhibitors in this recalcitrant malignancy.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell lymphoproliferative malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). ATL is an orphan disease with no curative drug treatment regimens urgently needing new combination therapy. HTLV-1-infected cells rely on viral proteins, Tax and HBZ (HTLV-1-b-ZIP factor), to activate the transcription of various host genes that are critical for promoting leukemic transformation. Inhibition of bromodomain and extraterminal motif (BET) protein was previously shown to collapse the transcriptional network directed by BATF3 super-enhancer and thereby induced ATL cell apoptosis. In the current work, by using xenograft, ex vivo, and in vitro models, we demonstrated that I-BET762 (BETi) synergized with copanlisib (PI3Ki) and bardoxolone methyl (NF-kappa Bi) to dramatically decrease the growth of ATL cells. Mechanistically, the triple combination exhibited synergistic activity by down-regulating the expression of c-MYC while upregulating the level of the glucocorticoid-induced leucine zipper (GILZ). The triple combination also enhanced apoptosis induction by elevating the expression of active caspase-3 and cleaved PARP. Importantly, the triple combination prolonged the survival of ATL-bearing xenograft mice and inhibited the proliferation of ATL cells from peripheral blood mononuclear cells (PBMCs) of both acute and smoldering/chronic ATL patients. Therefore, our data provide the rationale for a clinical trial exploring the multiagent combination of BET, PI3K/AKT, and NF-kappa B inhibitors for ATL patients and expands the potential treatments for this recalcitrant malignancy.

Adult T-cell leukemia (ATL) is an aggressive T-cell lymphoproliferative malignancy of regulatory T lymphocytes (Tregs), caused by human T-cell lymphotropic virus 1 (HTLV-1). Interleukin 2 receptor alpha (IL-2Rα) is expressed in the leukemic cells of smoldering/chronic ATL patients, leading to constitutive activation of the JAK/STAT pathway and spontaneous proliferation. The PI3K/AKT/mTOR pathway also plays a critical role in ATL cell survival and proliferation. We previously performed a high-throughput screen that demonstrated additive/synergistic activity of Ruxolitinib, a JAK1/2 inhibitor, with AZD8055, an mTORC1/C2 inhibitor. However, effects of unintended JAK2 inhibition with Ruxolitinib limits it therapeutic potential for ATL patients, which lead us to evaluate a JAK1-specific inhibitor. Here, we demonstrated that Upadacitinib, a JAK-1 inhibitor, inhibited the proliferation of cytokine-dependent ATL cell lines and the expression of p-STAT5. Combinations of Upadacitinib with either AZD8055 or Sapanisertib, mTORC1/C2 inhibitors, showed anti-proliferative effects against cytokine-dependent ATL cell lines and synergistic effect with reducing tumor growth in NSG mice bearing IL-2 transgenic tumors. Importantly, the combination of these two agents inhibited ex vivo spontaneous proliferation of ATL cells from patients with smoldering/chronic ATL. Combined targeting of JAK/STAT and PI3K/AKT/mTOR pathways represents a promising therapeutic intervention for patients with smoldering/chronic ATL.

Background Full application of cytokines as oncoimmunotherapeutics requires identification of optimal regimens. Our initial effort with intravenous bolus recombinant human interleukin-15 (rhIL-15) was limited by postinfusional reactions. Subcutaneous injection and continuous intravenous infusion for 10 days (CIV-10) provided rhIL-15 with less toxicity with CIV-10 giving the best increases in CD8 + lymphocytes and natural killer (NK) cells. To ease rhIL-15 administration, we shortened time of infusion. Treatment with rhIL-15 at a dose of 3–5 µg/kg as a 5-day continuous intravenous infusion (CIV-5) had no dose-limiting toxicities while effector cell stimulation was comparable to the CIV-10 regimen. Methods Eleven patients with metastatic cancers were treated with rhIL-15 CIV-5, 3 µg (n=4), 4 µg (n=3), and 5 µg/kg/day (n=4) in a phase I dose-escalation study (April 6, 2012). Results Impressive expansions of NK cells were seen at all dose levels (mean 34-fold), including CD56 bright NK cells (mean 144-fold for 4 µg/kg), as well as an increase in CD8 + T cells (mean 3.38-fold). At 5 µg/kg/day, there were no dose-limiting toxicities but pulmonary capillary leak and slower patient recovery. This led to our choice of the 4 µg/kg as CIV-5 dose for further testing. Cytolytic capacity of CD56 bright and CD56 dim NK cells was increased by interleukin-15 assayed by antibody-dependent cellular cytotoxicity (ADCC), natural cytotoxicity and natural killer group 2D-mediated cytotoxicity. The best response was stable disease. Conclusions IL-15 administered as CIV-5 substantially expanded NK cells with increased cytotoxic functions. Tumor-targeting monoclonal antibodies dependent on ADCC as their mechanism of action including alemtuzumab, obinutuzumab, avelumab, and mogamulizumab could benefit from those NK cell expansions and provide a promising therapeutic strategy. Trial registration numbers NCT01572493 , NCT03759184 , NCT03905135 , NCT04185220 and NCT02689453 .

Background: Despite advances in therapy of Hodgkin's lymphoma (HL), a proportion of patients will not respond or relapse. The authors had previously identified CD25, IL-2R alpha, as a target for systemic radioimmunotherapy of HL since most normal cells do not express CD25, but it is expressed by a minority of Hodgkin/Reed-Sternberg (HRS) cells and most Tregs rosetting around HRS cells. Study Design and Treatment: This was a single institution, nonrandomized, open-label phase I/II trial of radiolabeled Y-90-daclizumab, an anti-CD25 monoclonal antibody, BEAM (carmustine, etoposide, cytarabine, and melphalan) conditioning treatment followed by autologous hematopoietic stem cell transplant (ASCT). Four patients with refractory and relapsed HL were treated in this trial with 3 patients receiving a single dose of 564.6-574.6 MBq Y-90-daclizumab and the fourth patient receiving two doses of 580.9-566.1 MBq Y-90-daclizumab followed by high-dose chemotherapy and ASCT. Results: All 4 evaluable patients treated with Y-90-daclizumab obtained complete responses (CRs) that are ongoing 4.5-7 years following their stem cell transplant. The spectrum and severity of adverse events were mild and more importantly none of the patients, including several with multiple therapies before this treatment, developed the myelodysplastic syndrome. Discussion: Targeting by daclizumab was not directed primarily at tumor cells, but rather the nonmalignant CD25-expressing T cells adjacent to the HRS cells and Y-90-daclizumab provided strong enough beta emissions to kill CD25-negative tumor cells at a distance by a crossfire effect. Furthermore, the strong beta irradiation killed normal cells in the tumor microenvironment. Conclusions: Y-90-daclizumab (anti-CD25), high-dose BEAM chemotherapy and ASCT was well tolerated and yielded sustained complete remissions in all 4 patients with recurrent HL patients who completed their treatment. Significance: Despite advances, a proportion of patients with HL will not have a CR to their initial treatment, and some with CRs will relapse. They demonstrated that the addition of Y-90-daclizumab into the preconditioning regimen for refractory and relapsed HL patients with high-dose BEAM chemotherapy and ASCT provided sustained CRs in the 4 patients studied. Two of these patients were highly refractory to multiple prior treatments with bulky disease at entry into this study, including 1 patient who never entered a remission and had failed 6 different therapeutic regimens. Despite the small number of patients treated in this study, the sustained clinical benefit in these patients indicates a highly effective treatment. The daclizumab was directed primarily not at HRS cells themselves but toward nonmalignant T cells rosetting around malignant cells. Y-90 provided strong beta emissions that killed antigen nonexpressing tumor cells at a distance by a crossfire effect. Furthermore, the strong beta radiation killed normal cells in the tumor microenvironment that nurtured the malignant cells in the lymphomatous mass. The present study supports expanded analysis of Y-90-daclizumab as part of the regimen of ASCT in patients with refractory and relapsed HL.

Abstract Purpose: The first-in-human clinical trial with human bolus intravenous infusion IL15 (rhIL15) was limited by treatment-associated toxicity. Here, we report toxicity, immunomodulation, and clinical activity of rhIL15 administered as a 10-day continuous intravenous infusion (CIV) to patients with cancers in a phase I trial. Patients and Methods: Patients received treatment for 10 days with CIV rhIL15 in doses of 0.125, 0.25, 0.5, 1, 2, or 4 μg/kg/day. Correlative laboratory tests included IL15 pharmacokinetic (PK) analyses, and assessment of changes in lymphocyte subset numbers. Results: Twenty-seven patients were treated with rhIL15; 2 μg/kg/day was identified as the MTD. There were eight serious adverse events including two bleeding events, papilledema, uveitis, pneumonitis, duodenal erosions, and two deaths (one due to likely drug-related gastrointestinal ischemia). Evidence of antitumor effects was observed in several patients, but stable disease was the best response noted. Patients in the 2 μg/kg/day group had a 5.8-fold increase in number of circulating CD8+ T cells, 38-fold increase in total NK cells, and 358-fold increase in CD56bright NK cells. Serum IL15 concentrations were markedly lower during the last 3 days of infusion. Conclusions: This phase I trial identified the MTD for CIV rhIL15 and defined a treatment regimen that produced significant expansions of CD8+ T and NK effector cells in circulation and tumor deposits. This regimen has identified several biological features, including dramatic increases in numbers of NK cells, supporting trials of IL15 with anticancer mAbs to increase antibody-dependent cell-mediated cytotoxicity and anticancer efficacy.

AbstractObjectiveHuman T cell lymphotropic virus 1 (HTLV‐1)‐associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic, progressive, neurological disease. Chronic activation of CD8+ T cells, as evidenced by increased spontaneous lymphoproliferation and HTLV‐1‐specific cytotoxic T cells, has been demonstrated in HAM/TSP patients. Since IL‐2 and IL‐15 stimulate memory CD8+ T cell activity, these cytokines have been implicated in the immunopathogenesis of HAM/TSP. In this phase I trial, we evaluated the safety, pharmacokinetics, and ability of Hu‐Mikβ1, a humanized monoclonal antibody directed toward the IL‐2/IL‐15 receptor β‐chain (IL‐2/IL‐15Rβ: CD122), to saturate CD122 and regulate abnormal immune responses in patients with HAM/TSP by inhibition of IL‐15 action.MethodsHu‐Mikβ1 was administered intravenously at doses of 0.5 mg/kg, 1.0 mg/kg, or 1.5 mg/kg in a total of nine HAM/TSP patients. Five doses of Hu‐Mikβ1 were administered at 3‐week intervals. The clinical response was evaluated using standardized scales. Viral and immunologic outcome measures were examined including HTLV‐1 proviral load, T cell phenotypic analysis and spontaneous lymphoproliferation in HAM/TSP patients.ResultsThere was no significant toxicity associated with Hu‐Mikβ1 administration in HAM/TSP patients. Saturation of CD122 by Hu‐Mikβ1 was achieved in five out of nine HAM/TSP patients. Administration of Hu‐Mikβ1 was associated with inhibition of aberrant CD8+ T cell function including spontaneous lymphoproliferation and degranulation and IFN‐γ expression, especially in HAM/TSP patients that achieved CD122 saturation.InterpretationThe treatment with Hu‐Mikβ1 had a number of immunological effects on HAM/TSP patients although no clinical efficacy was observed. We also did not see any dose‐related toxicity.

Adult T cell leukemia/lymphoma (ATLL) is a frequently incurable disease associated with the human lymphotropic virus type I (HTLV-I). RNAi screening of ATLL lines revealed that their proliferation depends on BATF3 and IRF4, which cooperatively drive ATLL-specific gene expression. HBZ, the only HTLV-I encoded transcription factor that is expressed in all ATLL cases, binds to an ATLL-specific BATF3 super-enhancer and thereby regulates the expression of BATF3 and its downstream targets, including MYC. Inhibitors of bromo-domain-and-extra-terminal-domain (BET) chromatin proteins collapsed the transcriptional network directed by HBZ and BATF3, and were consequently toxic for ATLL cell lines, patient samples, and xenografts. Our study demonstrates that the HTLV-I oncogenic retrovirus exploits a regulatory module that can be attacked therapeutically with BET inhibitors.

AbstractThe cytokine IL15 is required for survival and activation of natural killer (NK) cells as well as expansion of NK-cell populations. Here, we compare the effects of continuous IL15 infusions on NK-cell subpopulations in cancer patients. Infusions affected the CD56bright NK-cell subpopulation in that the expansion rates exceeded those of CD56dim NK-cell populations with a 350-fold increase in their total cell numbers compared with 20-fold expansion for the CD56dim subset. CD56bright NK cells responded with increased cytokine release to various stimuli, as expected given their immunoregulatory functions. Moreover, CD56bright NK cells gained the ability to kill various target cells at levels that are typical for CD56dim NK cells. Some increased cytotoxic activities were also observed for CD56dim NK cells. IL15 infusions induced expression changes on the surface of both NK-cell subsets, resulting in a previously undescribed and similar phenotype. These data suggest that IL15 infusions expand and arm CD56bright NK cells that alone or in combination with tumor-targeting antibodies may be useful in the treatment of cancer. Cancer Immunol Res; 5(10); 929–38. ©2017 AACR.

Despite significant advances in the treatment of Hodgkin's lymphoma (HL), a significant proportion of patients will not respond or will subsequently relapse. We identified CD25, the IL-2 receptor alpha subunit, as a favorable target for systemic radioimmunotherapy of HL. The scientific basis for the clinical trial was that, although most normal cells with exception of Treg cells do not express CD25, it is expressed by a minority of Reed-Sternberg cells and by most polyclonal T cells rosetting around Reed-Sternberg cells. Forty-six patients with refractory and relapsed HL were evaluated with up to seven i.v. infusions of the radiolabeled anti-CD25 antibody (90)Y-daclizumab. (90)Y provides strong β emissions that kill tumor cells at a distance by a crossfire effect. In 46 evaluable HL patients treated with (90)Y-daclizumab there were 14 complete responses and nine partial responses; 14 patients had stable disease, and nine progressed. Responses were observed both in patients whose Reed-Sternberg cells expressed CD25 and in those whose neoplastic cells were CD25(-) provided that associated rosetting T cells expressed CD25. As assessed using phosphorylated H2AX (γ-H2AX) as a bioindicator of the effects of radiation exposure, predominantly nonmalignant cells in the tumor microenvironment manifested DNA damage, as reflected by increased expression of γ-H2AX. Toxicities were transient bone-marrow suppression and myelodysplastic syndrome in six patients who had not been evaluated with bone-marrow karyotype analyses before therapy. In conclusion, repeated (90)Y-daclizumab infusions directed predominantly toward nonmalignant T cells rosetting around Reed-Sternberg cells provided meaningful therapy for select HL patients.