Clinical Trials For Hematological Malignancies Research Articles

Abstract 6069: Discovery and preclinical development of orally bioavailable potent BTK degrader, and its early clinical development for the treatment of relapsed and refractory B-cell malignancies

Abstract Background : Bruton tyrosine kinase (BTK) is an important signaling hub that activates the B-cell receptor (BCR) signaling cascade, which is critical for growth and survival of B-cell lymphoma or leukemia. BTK inhibitors have shown anti-tumor activity in patients with B-NHL. However, nearly half of the patients on current BTK inhibitors discontinue the treatment due to adverse effects and/or mutation-induced drug resistance. A degrader is a heterobifunctional chemical compound aimed at eliminating disease-causing proteins, rather than simply inhibiting proteins’ enzymatic function, through the ubiquitin-proteasome system (UPS)-mediated protein degradation. This approach offers a unique solution for addressing relapse or refractory disease by removing overexpressed and mutated proteins, unlike traditional inhibitors. We thus designed UBX-382, a degrader targeting BTK. Results : UBX-382 showed superior degradation activity for both wild-type (WT) and mutant BTK proteins in a single-digit nanomolar range of half-maximal degradation concentration when compared to the competing degrader programs in diffuse large B-cell lymphoma cell line. UBX-382 effectively addressed 7 out of 8 previously reported resistant BTK mutants in in vitro experiments and outperformed ibrutinib, ARQ-531, and MT-802 in inhibiting tumor growth in murine xenograft models harboring WT or C481S mutant BTK-expressing TMD-8 cells. Remarkably, oral dosing of UBX-382 for <2 weeks led to complete tumor regression in 3 and 10 mg/kg groups in murine xenograft models. Following this, further optimization was carried out for potency and PK profile. We nominated the candidate for IND filing and are planning a phase 1 clinical trial. For the first-in-human, open-label, multicenter, phase 1 study, patients in part 1 (dose escalation with BOIN design) had R/R B-cell malignancies and had received at least 2 prior therapies. The candidate will be administered orally at 5 mg once daily followed by 2 days, for a 7-day schedule over 28-day cycles. Part 2 (dose expansion) consisted of disease-specific cohorts, including CLL/SLL, DLBCL, MCL, FL, MZL, and WM. The primary endpoints were safety and tolerability, along with the definition of the maximum tolerated dose. Secondary endpoints included pharmacokinetics/pharmacodynamics and preliminary efficacy. Conclusions : We have discovered potent BTK degrader exhibiting excellent anti-tumor activity in vitro and in vivo. In pre-clinical safety studies, the candidate of UBX demonstrated an acceptable safety profile. The candidate of UBX is currently preparing phase 1 clinical trials for hematological malignancies. Citation Format: Song Hee Lee, Sun-Mi Yoo, Ye Seul Lim, Han Wool Kim, Je Ho Ryu, Jong Hwan Lim. Discovery and preclinical development of orally bioavailable potent BTK degrader, and its early clinical development for the treatment of relapsed and refractory B-cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6069.

Engaging Underrepresented Patients in Hematology Clinical Trials through the LLS Impact (Influential Medicine Providing Access to Clinical Trials) Research Grant: A Multi-Institutional Effort

Introduction: Despite governmental and industry-sponsored efforts, clinical trial participation among rural residents and racial and ethnic minorities remains low. The NIH Revitalization Act of 1993 directed the NIH to establish guidelines for inclusion of women and minorities in clinical research. In 2015, the Food and Drug Administration launched an action plan to improve the quality of demographic subgroup data collection, identify barriers to enrollment, employ strategies to increase participation, and promote transparency of related data. However subsequent studies (Green et al. Health Aff. March 2022, Kanapuru et al. Blood Advances. March 2022.) showed no improvement in participation of racial minorities, including Blacks and Hispanics since this plan was enacted. Various complex system- and individual-based factors, including lack of clinical trial availability; lack of diversity in the investigator work force; scant patient and provider awareness of clinical trials; lack of trust in the health care system; and issues with access to care-often driven by financial, geographic, or social constraints (Allison et al. Cureus. Apr 2022.), and stringent eligibility criteria are deemed responsible. The Leukemia & Lymphoma Society (LLS) IMPACT (Influential Medicine Providing Access to Clinical Trials) research grant strives to bridge this unrelenting care gap. Methods: The LLS IMPACT program includes a 5-year research grant which was launched in 2021. The IMPACT grants support the establishment of clinical trial networks involving academic cancer centers (“Hubs”) linked to community clinics and oncology centers (“Spokes”). The program's overall goal is to provide patients access to trials through participation at the community sites. Initially, 3 institutional sites were selected to participate. These institutions had unique and tailored strategies to improve engagement of underrepresented patients, including black, indigenous, people of color, Hispanic, Latina/Latino, and people from rural communities in vastly different climates and local cultures. The IMPACT grant expanded to encompass 4 additional sites given the imminent needs and clamor of the hematology clinical trials community (Figure 1A). The catchment areas and strategies employed at each institution are summarized in the table (Figure 1B). Results: At the start of the grant period, focus was on building clinical research infrastructure and opening non-interventional clinical trials to teach personnel about clinical research and create relationships with patients. Other programs such as webinar series, tumor boards, technological advancements, and educational workshops were also established to enhance engagement among physicians, match patients to clinical trials, and to provide clinical trial education to potential patients. One trial that has seen early success is the CHIVE IMPACT trial, a non-interventional registry and biorepository which has enrolled 24 patients at a rural and underserved site as of July 2023. The purpose of CHIVE is to enroll patients who have clonal hematopoiesis (CH) or are at risk of CH and follow prospectively in efforts to understand risk of progression and potential for early intervention. The Universal Protocol is another biorepository trial which has more than tripled its enrollment number at a community site between 2021 and 2022. Of the 63 patients enrolled in 2022, 66% of them identified as a race other than White. As our core goal is to increase access to interventional trials, we hope to bring industry sponsored phase II and phase III studies to underrepresented areas that serve a broad patient population. Lack of financial resources, lack of transportation and distance to trial sites, and residual distrust of the medical community (e.g., legacy of Tuskegee experiments) are barriers the grantees are focused on overcoming to enroll the intended populations into clinical trials. Conclusion: The innovative strategies employed to expand access to clinical trials for underrepresented population at the various institutions through the LLS's IMPACT research grant can be utilized during clinical trials design and implementation phases to improve generalizability of clinical trials in hematologic malignancies. In the third year of this program, 7 participating sites are engaging impactful strategies (Figure 1B) which will be reported at the end of the grant period.

Novel Pi3kδ Inhibitor Roginolisib Synergizes with the Bcl-2 Inhibitor Venetoclax in Hematological Malignancies

Roginolisib (IOA-244) is a first in class allosteric modulator and non-ATP competitive, selective PI3Kδ inhibitor currently in a Phase 1 clinical study in lymphoma and solid tumors. Initial structural and biochemical studies identified unique chemical structure, excellent selectivity, and excellent PK properties for roginolisib as compared to earlier PI3Kδ inhibitors, while the clinical trial has demonstrated a favorable safety profile. Consistent with prior PI3Kδ inhibitors, roginolisib inhibits the in vitro growth of lymphoma cells. In contrast to other PI3Kδ inhibitors, roginolisib activity is correlated with the expression levels of PIK3CD, suggesting specific and on target cancer cell-intrinsic effects (PMID: 37066023). To identify rational combination strategies, initial pharmacological screening of 474 compounds in combination with roginolisib was carried out using a MTT assay in the lymphoma cell lines HH (cutaneous T cell lymphoma, CTCL) and SP-53 (mantle cell lymphoma, MCL). Initial screening identified that roginolisib synergized with the bcl-2 inhibitor venetoclax in the HH cell line with a combination index value (CI) of 0.003 by the Chou-Talalay method. To further validate this finding, the combination of roginolisib with venetoclax or with another bcl-2 inhibitor S55746 was tested in a broad range of lymphoma cell lines including GRANTA519, JVM2, SP49 (MCL); FARAGE, TMD8 (diffuse large B cell lymphoma); MEC1 (chronic lymphocytic leukemia); MJ (cutaneous T cell lymphoma); and YT (NK lymphoma). The combination showed synergism in all the cell lines (CI 0.81 - 0.05) except SP49 (CI- 1.3). Similarly, the combination of roginolisib with S55746 showed synergism in most of the cell lines (CI- 0.46 - 0.089), additive effect in SP49 (CI- 1) and antagonistic effect in GRANTA519 (CI- 1.3) and FARAGE (CI- 2.17). To assess the tumor-intrinsic effect of roginolisib in patient derived CLL cells, PBMCs isolated from CLL patients responding to prior BTK inhibitor (i) (n=4) or progressed on BTKi (n=6) were tested to check the effect of roginolisib on BCR signalling. Cells were treated with increasing doses of roginolisib from 0.625 μM to 5 μM in the presence of anti-IgM. Other BCRi such as idelalisib, duvelisib and acalabrutinib were used at 5 μM concentrations as positive controls. Roginolisib showed a dose dependent suppression of the activity of BCR downstream kinases such as AKT and ERK. The suppression of phosphorylation of AKT and ERK were comparable with other BCRi tested. Additionally, the apoptosis analysis by annexin/7AAD showed comparable activity of roginolisib with idelalisib, duvelisib or acalabrutinib at 5 μM concentration. To investigate the possible synergy of roginolisib with venetoclax in CLL patient samples who are BTKi responders (n=6) or BTKi progressors (n=8), apoptosis analysis was carried out in patient PBMCs. Viability of CLL cells following 48h of ex vivo treatment with increasing concentrations of roginolisib (0.625 to 5 μM) and venetoclax (1 to 8 nM) alone or in combination was tested. Both the BTKi responders and progressors showed strong synergy with the combination, with slightly better cell killing activity in BTKi progressors ( p=0.007) than responders ( p=0.019). To understand the mechanism by which roginolisib increases the sensitivity to venetoclax, changes in the expression levels of various Bcl-2 family proteins that have been implicated in venetoclax resistance such as Mcl-1, Bcl-xL, Bcl-2, A1 and BIM were measured by immunoblotting. Changes in expression were evaluated in PBMCs from both the BTKi responders (n=8) and progressors (n=7) after 24h treatment with 0.625 and 5 μM concentrations of roginolisib. A significant dose dependent downregulation of Mcl-1 was observed compared to DMSO treated cells in both BTKi responders ( p=0.0033) and progressors ( p= 0.0025). In addition, a significant increase in proapoptotic BIM EL was also observed at both the 0.625 μM ( p=0.0054) and 5 μM ( p=0.0194) concentrations compared to DMSO. In summary, the novel PI3Kδ selective inhibitor roginolisib shows tumor cell killing on various hematologic malignancies including CLL cells from patients with disease progression on BTK inhibitors. In addition, roginolisib synergized with venetoclax in lymphoma cell lines and CLL patient samples. Our data support extending this combination strategy to clinical trials in hematological malignancies.

Abstract 4558: High-throughput, high content Imaging assay for assessing solid tumor phagocytosis in 3D spheroid model

Abstract Emerging studies have demonstrated that innate immune checkpoints, regulating Tumor-associated Macrophage (TAM) phagocytic activity, play a crucial role in immune escape and survival of cancer cells. CD47-SIRPα axis is the best studied example of the “don’t eat me” signal, frequently overexpressed on cancer cell. Targeting of CD47 protein has shown impressive results in clinical trials in hematologic malignancies but remained challenging for solid tumors therapy. Therefore, tools facilitating the development of novel innate immune checkpoint inhibitors are of great interest. To address that unmet need, we established a high-throughput, 384-well-format assay for efficacy assessment of compounds inducing macrophage phagocytosis. As a model of solid tumor, we employed 3D spheroids aggregated of human cancer cell lines (A375, HCT116, MCF7, SKOV3) expressing GFP or PDX material (LXFA1647 lung adenocarcinoma, MEXF2106 melanoma) and cancer associated fibroblasts, as well as Monocyte-Derived Macrophages (MDMs) which altogether were co-aggregated to form spheroids mimicking the tumor microenvironment and immune-competence. In parallel MDMs were co-cultured with matured spheroid to emulate tumor infiltration. Both models were cultured in automation and High Content imaging compatible Akura™ 384-well plate. To evaluate our system, we targeted CD47-SIRPα axis by treatment of 3D spheroid models with αCD47 antibody (H6D12) in combination with atezolizumab (αPD-L1 antibody). Tumor viability and growth were assessed by fluorescence measurements and ATP level. Phagocytosis of fluorescently labeled tumor cells was imaged by confocal microscopy and quantified by inhouse developed analysis pipeline. Immune cell activation was evaluated by a cytokine bead array. The treatment of cell line-based 3D models with αCD47 antibody resulted in an increased number of phagocytic macrophages followed by a decrease of fluorescence and size of tumor spheroids in a dose-dependent manner. Moreover, we observed an induced secretion of TNFα, IL-6, IL-10 and IL-RA after 48h. Similarly, in PDX-based models, we observed decreased spheroid size and ATP level at day 7. Notably, αCD47 antibody-induced level of cytokines was further increased in combination with atezolizumab. To conclude, we have developed a human disease relevant, high-throughput assay for the evaluation of novel therapeutic modalities targeting phagocytosis. Due to compatibility with microscopy and most of the biochemical assays, it represents a powerful tool for clinical candidate development. Citation Format: Michal Rudnik, Özlem Yavaş Grining, Nadezhda Rotankova, Silvan Strebel, Francesca Chiovaro, Olivier Frey, Irina Agarkova, Wolfgang Moritz. High-throughput, high content Imaging assay for assessing solid tumor phagocytosis in 3D spheroid model. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4558.

Cyclin-Dependent Kinase 4/6 Inhibitor Palbociclib Synergizes with BH3-Mimetics in Experimental Models of Relapsed/Refractory Mantle Cell Lymphoma

Introduction: Mantle cell lymphoma (MCL) is an aggressive subtype of B-cell non-Hodkin lymphomas characterized by cyclin D1 upregulation. The complex of upregulated cyclin D1 and cyclin-dependent kinases (CDK) 4 and 6 deregulates G1/S cell cycle transition of malignant lymphocytes, which represents a rationale druggable target. Palbociclib, a CDK 4/6 inhibitor approved for the therapy of patients with breast cancer, demonstrated single-agent clinical activity in relapsed/refractory (R/R) MCL. BH3-mimetics bind to an anti-apoptotic BCL-2 proteins (Bcl-2, Bcl-xL or Mcl-1) and thereby block their anti-apoptotic function. Specific Bcl-2 inhibitor venetoclax, the only FDA approved member of BH3-mimetics, is currently being tested in numerous clinical trials in hematological malignancies. Interestingly, the combination of palbociclib and venetoclax showed promising results in patients with breast cancer but has never been tested in patients with MCL. Methods: Experimental therapy aimed at inhibition of CDK by palbociclib and anti-apoptotic BCL-2 proteins using venetoclax, S63845 and A1155463 was performed on nine MCL cell lines and four patient-derived xenograft (PDX) models from patients with R/R MCL. Mitochondrial priming to apoptosis was assessed by BH3 profiling. Expression of selected cell cycle regulators, pro-, and anti-apoptotic proteins was evaluated before and after exposure to palbociclib by western blotting both in vitro and in vivo. Spectrum of BCL-2-bound BH3-only proteins were detected by immunoprecipitation of MCL tumors ex vivo 24 and 48 hours after start of palbociclib therapy (compared to tumors obtained from untreated controls). Impact of palbociclib on energo-metabolic pathways in MCL cells was measured by SeaHorse assay. MCL clones with knockdown or overexpression of CDKN2A, MYC, CDK4 and RB1 were used to evaluate impact of these aberrations on the sensitivity to palbociclib (and venetoclax). Results: Synergistic effect of palbociclib was observed in combination with all BH3-mimetics (venetoclax, S63845 and A1155463) in vitro, and confirmed in vivo on PDX R/R MCL models using venetoclax, as the only FDA approved member. Exposure of MCL-bearing mice to palbociclib induced downregulation of D-type cyclins, cyclin A, Rb1 and Mcl-1 proteins. Even though single-agent palbociclib had limited cytotoxic (proapoptotic) effect, it increased pro-apoptotic mitochondrial priming. Immunoprecipitation experiments revealed that the level of Bim bounded to Bcl-2 was not significantly changed, and the level of Bim bounded to Bcl-xL was increased 24 hours after exposure to palbociclib. Curiously, palbociclib significantly increased level of basal and maximal oxidative phosphorylation after cultivation with MCL cells for 72 hours (but not 24 hours). Pre-treatment of MCL cells with palbociclib showed even greater synergy than simultaneous palbociclib and BH3-mimetic application. MCL cell clones with RB1 knockdown became resistant to palbociclib. Susceptibility of MCL clones with knockout of CDKN2A, overexpression of MYC, and overexpression of CDK4 to palbociclib and venetoclax was not significantly changed. Conclusion: Our data strongly support investigation of palbociclib in combination with venetoclax as an innovative treatment strategy for chemoresistant MCL patients without RB1 deletion. Although we demonstrated that palbociclib increases pro-apoptotic mitochondrial priming and induces metabolic stress, the detailed contribution of these changes to the observed synergy are under investigation.

Toxicity Reporting Is Inconsistent and Incomplete, and Subjective Minimizing Language Is Common in Acute Leukemia Clinical Trials: A Systematic Review of Randomized Controlled Trials Presented at ASH between 2017-2021

Introduction: Despite calls for greater transparency in reporting harms in cancer clinical trials, data on drug toxicity continues to be obscured by incomplete reporting and use of subjective, minimizing language. Subjective terms such as "acceptable" or "tolerable" toxicity are commonly employed in peer-reviewed publications in oncology (Gyawali et al. BMJ 2018). The use of subjective language that minimizes harms in clinical trials can adversely impact informed consent and shared decision-making by overlooking the fact that only individual patients can determine if a therapy is tolerable. The scope of this problem in clinical trials in hematologic malignancies and at medical conferences, however, remains unknown. To further assess this issue, we conducted a systematic review of abstracts presented at ASH annual meetings from 2017-2021 to characterize toxicity reporting and use of subjective, minimizing language in phase 3 clinical trials in acute leukemia. Methods: Following a pilot phase to identify and define minimization terms, we conducted a systematic search of all ASH abstracts from 2017-2021. Phase 3 randomized controlled trials in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) were included; subset analyses, long-term follow up studies and supportive care trials were excluded. Subjective, minimizing language was defined a priori as use of "acceptable", "tolerable", "manageable", "favorable", "feasible" "safe", and/or "limited" in reference to treatment-related adverse events (AE), which falsely suggested that patients deemed the therapy as such without evaluating patient experiences. Primary toxicity outcome assessment included fatal AE (FAE), serious AE (SAE), and use of common terminology criteria for AE (CTCAE), as well as absent and incomplete AE reporting, defined in Table 1A. Complete severe AE reporting was defined as reporting of cumulative rates (per 100 patients; %) of CTCAE grade ≥3 toxicities or cumulative SAE. An across-disease assessment was performed including phase 3 clinical trials in multiple myeloma and lymphoma from the same time period. Results: 341 studies in acute leukemia underwent abstract screening, of which 40 met inclusion criteria. Study characteristics are reported in Table 1A. AE reporting was variable across trials. Ten trials (25%) provided no information on AE in their abstract, and 6 (15%) had incomplete AE reporting. Subjective, minimizing language was used to describe AE data in 16 trials (40%), with "tolerable" and "acceptable" being the most frequently used terms, and a total of 26 (65%) studies had either absent AE reporting or used minimizing terms (Table 1A). Minimizing language was seen across a range of different study types, including trials in patients with adult and pediatric leukemia, trials of systemic therapies and stem cell transplantation, and trials in frontline and relapsed/refractory settings. Severe toxicities were reported in 10 of the 16 trials that used minimizing language (62.5%) and FAE in 6 of 16 (37.5%). In experimental arms of trials using minimizing terms, rates of CTCAE grade ≥3 AE or SAE ranged from 17-97.3%, and rates of fatal AE from 0-19.5% (Table 1B). FAE and severe AE rates were similar or numerically higher in abstracts that used minimizing terms compared to those abstracts that did not. A total of 65 abstracts reporting results of randomized clinical trials in multiple myeloma and lymphoma (including Hodgkin and non-Hodgkin lymphoma) were available for across-disease assessment and demonstrated similar high rates of absent and incomplete AE reporting, as well as subjective, minimizing terms, used to describe a wide range of severe AE (Table 1B). Discussion: This systematic review of ASH abstracts highlights inconsistent, incomplete, and often absent toxicity reporting, as well as frequent use of subjective, minimizing language. The findings suggest that formal toxicity minimization and subjective minimizing terms are common. Conference abstracts often form the first impression of a clinical trial and can have a disproportionate influence on physician perspectives, thus impacting clinical practice. These findings will inform a larger systematic review to inform policy to improve reporting transparency at hematology and oncology conferences. #co-senior authors Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Protein Arginine Methyltransferases as Therapeutic Targets in Hematological Malignancies.

Arginine methylation is a common post-translational modification affecting protein activity and the transcription of target genes when methylation occurs on histone tails. There are nine protein arginine methyltransferases (PRMTs) in mammals, divided into subgroups depending on the methylation they form on a molecule of arginine. During the formation and maturation of the different types of blood cells, PRMTs play a central role by controlling cell differentiation at the transcriptional level. PRMT enzymatic activity is necessary for many cellular processes in hematological malignancies, such as the activation of cell cycle and proliferation, inhibition of apoptosis, DNA repair processes, RNA splicing, and transcription by methylating histone tails' arginine. Chemical tools have been developed to inhibit the activity of PRMTs and have been tested in several models of hematological malignancies, including primary samples from patients, xenografts into immunodeficient mice, mouse models, and human cell lines. They show a significant effect by reducing cell viability and increasing the overall survival of mice. PRMT5 inhibitors have a strong therapeutic potential, as phase I clinical trials in hematological malignancies that use these molecules show promising results, thus, underlining PRMT inhibitors as useful therapeutic tools for cancer treatment in the future.

Abstract 2764: Safety and efficacy of CAR T and TCR therapies in solid tumors: A systematic review and meta-analysis, including a comparison with five phase II trials in hematologic malignancies used for the first FDA approvals of these agents

Abstract Background: Adoptive cellular therapies (ACT) have met with significant success in hematologic malignancies. The number of ACT trials in solid tumors has been increasing, however data are limited on the overall safety and efficacy of ACT in this population. We aimed to conduct a systematic review and meta-analysis looking specifically at TCR and CAR-T in solid tumors and rates of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) relative to the current approved agents in hematologic malignancies. Methods: We conducted a systematic review of published studies/abstracts from January 2015 up to and including July 2021, selecting those that included ≥ 5 patients. Endpoints included rates and differences in CRS and ICANS. Response rates were evaluated. Statistical tests in the pooled data included χ2 and multivariable logistic regression. Results: This meta-analysis included a total of 1,250 patients [566 patients with solid tumors who had received ACT in phase I, II or I/II clinical trials; a comparison was made with five phase 2 clinical trials in hematologic malignancies used for the first FDA approvals of these agents (JULIET, ZUMA-1, ZUMA-2, TRANSCEND and KARMMA), encompassing 684 heme malignant patients]. Rates of CRS of any grade, CRS ≥ grade 3, ICANS of any grade, and ICANS ≥ grade 3 in solid tumors were 33.0%, 3.8%, 2.3% and 2.1%, respectively. Fever, hypotension, and hypoxia were experienced by 37.4%, 18.5%, and 8.5% of solid tumor patients, respectively. CRS, ICANS, fever and hypoxia in solid tumor patients did not differ by whether the ACT received was TCR or CAR T. Objective response (ORR = CR + PR) in patients with solid tumors was higher with TCR compared with CAR-T [odds ratio (OR) = 3.1, P=0.001] and with NY-ESO-1 than other targets (OR=2.0, P=0.031). Compared to hematologic patients treated with ACT, solid tumor patients treated with adoptive cellular therapies were significantly less likely to experience CRS of any grade (62.4% vs. 33.0%, P<0.001), CRS ≥ grade 3 (7.3% vs. 3.8%, P=0.043), fever (50.3% vs. 37.4%, P=0.001), hypoxia (34.1% vs. 8.5%, P<0.001) or hypotension (29.5% vs. 18.5%, P=0.006), ICANS of any grade (29.7% vs. 2.3%, P<0.001), or ICANS ≥ grade 3 (13.9% vs. 2.1%, P<0.001). However, objective response (20.1% vs. 75.4%, P<0.001) and clinical benefit (CBR = CR + PR + SD) (62.6% vs. 90.9%, P<0.001) rates for ACT were lower in patients with solid tumors than in patients with hematologic malignancies. Conclusions: CRS and ICANs were less prevalent in solid tumor cellular therapies. Based on this analysis, T-cell therapies in solid tumors are relatively safe, but further studies with larger populations and longer follow up are needed to address the role of these treatments in cancer. Citation Format: Mirella Nardo, Ji Y. Son, Goldy G. George, David S. Hong. Safety and efficacy of CAR T and TCR therapies in solid tumors: A systematic review and meta-analysis, including a comparison with five phase II trials in hematologic malignancies used for the first FDA approvals of these agents [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2764.

Abstract 4257: ADG153-G1, a highly differentiated anti-CD47 IgG1 SAFEbody, demonstrates potent in vivo anti-tumor activities with enhanced ADCC/ADCP effects and significantly reduced RBC-related and antigen sink liabilities

Abstract Anti-CD47 antibodies of the IgG4 isotype have shown promising activities in clinical trials for hematologic malignancies, mainly in the combination setting. To overcome the fundamental challenge of developing an anti-CD47 antibody of an active Fc isotype for strong anti-tumor activities without the safety (e.g., anemia) and pharmacokinetic (e.g., antigen sink) liabilities, we set out to design anti-CD47 antibodies of active isotypes that allow us to decouple efficacy from safety and PK liabilities. Our NEObody࣪ technology enables us first to identify an anti-CD47 antibody targeting a novel epitope on CD47. Next, our SAFEbody® technology for precision masking enables us to mask the CD47 binding sites to create the masked antibody in active IgG1 isotype called ADG153-G1 SAFEbody, which can be conditionally activated to bind and inhibit CD47 on tumor cells for potent tumor killing with much improved safety and pharmacokinetic profiles. In vitro studies showed that the activated ADG153-G1 SAFEbody blocked CD47 binding to SIRPα, bound to the CD47 protein, CD47+ tumor cell lines, and human RBCs, and induced strong ADCC/ADCP activities. In contrast, the unactivated ADG153-G1 SAFEbody demonstrated high masking efficiency (ME) with significantly reduced activities (>110-1300× ME) in the same assays. While anti-CD47 antibodies such as the Hu5F9 analog caused in vitro human RBC hemagglutination, the ADG153-G1 SAFEbody in activated and unactivated forms did not show this effect at comparable concentrations. Consistent with its enhanced ADCC/ADCP potential in IgG1 isotype, in the CD47+ Raji tumor model in SCID mice (with functional NK cells and macrophages), the unmasked ADG153-G1 and masked SAFEbody demonstrated better anti-tumor activities than their IgG4 unmasked and masked SAFEbody counterparts. In exploratory single-dose toxicology studies in cynomolgus monkeys, the ADG153-G1 SAFEbody showed significantly less reduction than the Hu5F9 analog in RBCs and hemoglobin. The Hu5F9 analog at 10 mg/kg caused an ~49% maximum decrease in RBCs, while the ADG153-G1 SAFEbody at 10 and 30 mg/kg showed only 8% and 40% maximum reductions, respectively. Consistent with a reduced antigen sink effect due to lower RBC binding, the ADG153-G1 SAFEbody had more favorable pharmacokinetic properties than the Hu5F9 analog (~8× longer t1/2 and ~5× higher AUC) at 10 mg/kg. Taken together, these results indicate that the ADG153-G1 SAFEbody is a differentiated anti-CD47 IgG1 antibody prodrug with strong ADCC/ADCP potential and significantly reduced anemia-related and antigen sink liabilities, supporting its advancement into clinical development. Citation Format: Bin Cai, Aaron N. Nguyen, Songmao Zheng, Jianfeng Shi, Guizhong Liu, Yan Li, Felix Du, Peter Luo, Jiangchun Xu. ADG153-G1, a highly differentiated anti-CD47 IgG1 SAFEbody, demonstrates potent in vivo anti-tumor activities with enhanced ADCC/ADCP effects and significantly reduced RBC-related and antigen sink liabilities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4257.

Natural killer cells: Innate immune system as a part of adaptive immunotherapy in hematological malignancies.

Natural killer (NK) cells are part of a phylogenetically old defense system, which is characterized by its strong cytolytic function against physiologically stressed cells such as tumor cells and virus-infected cells. Their use in the treatment of hematological malignancies may be more advantageous in several ways when compared with the already established T lymphocyte-based immunotherapy. Given the different mechanisms of action, allogeneic NK cell products can be produced in a non-personal based manner without the risk of the formidable graft-versus-host disease. Advanced manufacturing processes are capable of producing NK cells relatively easily in large and clinically sufficient numbers, useable without subsequent manipulations or after genetic modifications, which can solve the lack of specificity and improve clinical efficacy of NK cell products. This review summarizes the basic characteristics of NK cells and provides a quick overview of their sources. Results of clinical trials in hematological malignancies are presented, and strategies on how to improve the clinical outcome of NK cell therapy are discussed.

Abstract 1951: SMAC mimetic and BET inhibitor - a promising combination for solid cancer treatment

Abstract SMAC mimetics (SMACm), drugs that mimic natural antagonists of Inhibitor of Apoptosis (IAP) are in clinical trials for hematological malignancies and solid cancers. The clinical benefit for patients in monotherapy was so far dismal. Hence, current clinical evaluation of SMACm focuses on combinations, in particular with checkpoint inhibitors and/or radiation therapy. The BET family protein BRD4 is a “reader” of epigenetic information and binds to acetylated chromatin to act as a key regulator of transcription. BET inhibitors (BETi) were tested in numerous clinical trials as novel treatment option for hematological and solid cancers. Like SMACm, monotherapy with BETi showed only moderate clinical activity stressing the importance of combination trials. BI 891065 a monovalent, oral SMACm, with a favorable safety profile allowing continuous dosing, is in Clinical Phase I (NCT03166631, NCT04138823). BI 894999 is a very potent and selective oral BETi, administered by intermittent dosing in Clinical Phase I (NCT02516553). We studied the combinatorial effect of both compounds in vitro across a large number of human tumor cell lines (lung, colorectal, pancreatic, and gastric cancer) in proliferation assays using Bliss synergy analysis and IncuCyte ZOOM® live cell imaging, and in vivo in three independent models. Of the 60+ cancer cell lines, around 30% showed synergy when treated with the BI 891065 + BI 894999 combination, irrespective of indication. Efficacy correlated with downmodulation of the key apoptosis regulator XIAP by BI 894999. In most of the cell lines tested, the synergistic effect was blocked by addition of the TNFα scavenger Enbrel and/or the apoptotic pathway inhibitor zVAD. In vivo efficacy was tested in two PDAC xenograft models (one immunocompetent and one immunodeficient) and one CRC model at clinically relevant doses. Daily oral application of both compounds was well tolerated and did not lead to drug-drug interactions. Target engagement markers were modulated as expected (cIAP1 degradation for SMACm and Hexim1 induction for BETi) and not compromised by the combination. Tumor growth inhibition in the BxPC3 pancreas model achieved 22% TGI for 50 mg/kg BI 891065, 70% TGI for 2 mg/kg BI 894999, and 96% TGI for the combination. In the Pan02 pancreas model 9% TGI for 50 mg/kg BI 891065, 30% TGI for 4 mg/kg BI 894999 and 92% TGI for the combination were recorded. Evaluation of the cellular composition of the tumor microenvironment in this immunocompetent model showed distinct changes evident of a reduced immuno-suppressive milieu upon combination treatment. Combination effects on tumor growth in the CRC model LoVo were far less pronounced. These preclinical in vitro and in vivo data are highlighting the potential of a SMACm/BETi combination for the treatment of solid cancers. The identification of patient selection markers for this combination will be necessary for advancing this concept into pivotal clinical trials. Citation Format: Paula-Elena Traexler, Dominik Arnold, Florian Ebner, Ksenija Slavic-Obradovic, Robin Jacob, Ha Pham Thi Thanh, Martin Aichinger, Anke Baum, Andreas Wernitznig, Daniel Gerlach, Maria-Antonietta Impagnatiello, Valeria Santoro, Sabine Olt, Dirk Scharn, Regina Ruzicka, Reniqua P. House, Mary Y. Murphy, Ulrich Reiser, Harald Engelhardt, Vittoria Zinzalla, Thorsten Laux, Flavio Solca, Ulrike Tontsch-Grunt. SMAC mimetic and BET inhibitor - a promising combination for solid cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1951.

Prognostic Factors and Survival Outcomes in Phase I Patients with Hematologic Malignancies

Introduction: Patient selection is a challenge in designing effective phase I clinical trials in hematologic malignancies. Potential candidates typically have relapsed or refractory disease, and have had poor response to multiple prior lines of therapy. Such patients are at risk for early death, which reduces both the scientific yield and the therapeutic value of clinical trials: patients whose disease has already entered a terminal phase, and who subsequently die within a few months, provide little meaningful data to advance the understanding of an experimental treatment, and likely derive little clinical benefit from that treatment.Currently, eligibility criteria for most trials rely on ad hoc laboratory thresholds, and on subjective assessments of performance status and life expectancy. It is desirable to have an objective, statistically validated means of predicting survival, to optimize patient selection for phase I clinical trials. A prognostic scoring system for this purpose has been developed and validated for patients with solid tumors (Garrido-Laguna et al. Cancer . 2012;118(5):1422-1428); this model incorporates variables on tumor type and number of metastatic sites, which are not directly applicable outside of solid tumors. Similar work has recently been reported in hematologic malignancies (Benajiba et al. Anti-cancer drugs . 2017;28(5):540-545), using only three variables: performance status, serum albumin, and disease class. We developed a novel prognostic scoring system to estimate progression free (PFS) and overall (OS) survival for patients enrolled in phase I clinical trials for treatment of hematologic malignancy.Methods: We retrospectively reviewed the electronic medical records of 106 patients enrolled in phase I clinical trials for treatment of hematologic malignancies at the UT Health San Antonio Cancer Center between 2000 and 2014. Descriptive, univariate, and multivariate analyses were performed to determine the parameters that carry prognostic significance. Cox proportional hazards regression models of Progression Free and Overall Survival (PFS, OS) were used for multivariate analyses. A backward elimination process with a relaxed P-value (0.2) threshold was used to select variables for adjustment.Results: Our analysis identified Hispanic ethnicity (P=0.03), low albumin level (<3.5 g/dL), low hemoglobin (<10 g/dL, P=0.02), hyperbilirubinemia (>1.0 mg/dL, P=0.03), abnormal white blood cell count (<4 k/µL or >10 k/µL, P<0.01), elevated lactate dehydrogenase (LDH) (>240 IU/L, P<0.01), and diagnosis of acute leukemia (P<0.01) as independent predictors of poor overall survival. The patient cohort was stratified by risk score into good (0-1), intermediate (2-4), and poor (5-7) risk categories, which were compared with respect to PFS and OS using Kaplan-Meier curves and log rank testing (see figures 1 and 2).Conclusion: A simple score incorporating diagnosis, ethnicity, albumin, hemoglobin, bilirubin, white blood count, and LDH can identify patients with advanced hematologic malignancy who are likely to have short OS and PFS. Efforts are underway to validate this score against a separate cohort of phase I patients. Once validated, it could be incorporated in phase I trial design, potentially making these trials easier, faster, and more cost-effective to conduct, while allocating experimental treatments to those patients most likely to derive benefit. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Phase I/II Study of Liposomal Doxorubicin (DOX) in Combination with Selinexor (SEL) and Dexamethasone (Dex) for Relapsed and Refractory Multiple Myeloma (RRMM)

Background: SEL, an oral first-in-class inhibitor of XPO1 showed activity in clinical trials for hematologic malignancies. SEL inhibits DNA damage repair and exhibits marked synergy with doxorubicin in preclinical myeloma models. SEL/Dex results in a 20% response rate in penta-refractory myeloma patients. We report here the results of a phase I/II trial of SEL in combination with DOX and Dex in patients with RRMM.Methods: Eligible patients had RRMM and received ≥ 2 prior therapies including lenalidomide and a proteasome inhibitor. Treatment consisted of a loading phase with SEL and Dex for 1-2 weeks; an induction phase with DOX 20 mg/m2 IV D1, SEL and Dex (once weekly) and a maintenance phase of weekly SEL/Dex. Two loading phases were evaluated: A. SEL/Dex twice weekly for 2 weeks, B. One dose of SEL/Dex (table 1). Primary and secondary end points: maximum tolerated dose (MTD) / recommended phase II dose (RP2D) of the combination, and overall response rate (ORR) per International Myeloma Working Group (IMWG) criteria.Results: Twenty-seven patients were enrolled (median age of 62 years, median of 6 prior lines (range 2-10)). No dose limiting toxicities (DLT) were noted in dose level (DL) 1. Two patients experienced a DLT in DL2 (Gr4 thrombocytopenia and Gr 3 nausea). The loading phase was shortened to 1 dose of SEL (80mg) on day -7 (DL2m). 1/6 patients experienced a DLT on DL2m (Gr3 hyponatremia). Two patients experienced a DLT in dose level 3m (Grade 3 ALT and Grade 3 confusion). The recommended phase II dose was determined to be DL2m (SEL 80mg D1,8,15, DOX 20mg/m2 D1 and Dex 40 mg D1,8,15). Three patients died on study (1 from RSV pneumonia, one from pneumocystis Jiroveci and 1 from advanced myeloma). The most common Grade 3/4 at least possibly related adverse events are as follows: thrombocytopenia 33%, neutropenia 33%, asymptomatic hyponatremia 30%, anemia 26%, nausea / vomiting 11%, hyperglycemia 11%, diarrhea 7%, and fatigue 7% (table 2). Of the 14 patients treated at the RP2D, one was not evaluable (NE), one had a PR and 1 a MR at the time of this analysis. Per protocol, this current level of response does not justify proceeding with the second stage of the phase II study. Of the 27 total patients treated, we noted 2 VGPR, 2 PR, 3MR, 8SD, 4NE with an ORR of 15%, clinical benefit rate (MR and better) of 26% by intent to treat. There was increased nuclear localization of Ikβ post selinexor treatment in responders compared to non-responders (Nuclear / cytoplasmic ratio mean 1.15 ±0.06 versus 0.93 ±0.09; p=0.04).Conclusions: The addition of DOX to SEL/Dex, while reasonableywell tolerated, does not appear to improve the ORR noted with SEL/Dex in this heavily pretreated patient population. [Display omitted] DisclosuresBaz:BMS: Research Funding; celgene: Honoraria, Research Funding; karyopharm: Research Funding; takeda: Research Funding; merck: Research Funding; Sanofi: Research Funding. Zonder:Janssen: Consultancy; BMS: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Takeda: Consultancy; Pharmacyclics: Other: Data Safety Monitoring Committee; Prothena: Consultancy.

Expedient Total Syntheses of Pladienolide-Derived Spliceosome Modulators

Atom and step economical total syntheses of spliceosome modulating natural products pladienolides A and B are described. The strategic functionalization of an unsaturated macrolide precursor enabled the most concise syntheses of these natural products to date and provides convenient, flexible access to stereodefined macrolides to streamline medicinal chemistry explorations. Notably, this synthetic route does not depend on protecting group manipulations that traditionally define synthesis planning for polyhydroxylated natural products of polyketide origin. Its utility is further demonstrated by the enantioselective total synthesis of H3B-8800, a hitherto semisynthetic pladienolide-derived spliceosome modulator undergoing clinical trials for hematological malignancies.

Artemisinin-type drugs for the treatment of hematological malignancies.

Qinghaosu, known as artemisinin (ARS), has been for over two millennia, one of the most common herbs prescribed in traditional Chinese medicine (TCM). ARS was developed as an antimalarial drug and currently belongs to the established standard treatments of malaria as a combination therapy worldwide. In addition to the antimalarial bioactivity of ARS, anticancer activities have been shown both in vitro and in vivo. Like other natural products, ARS acts in a multi-specific manner also against hematological malignancies. The chemical structure of ARS is a sesquiterpene lactone, which contains an endoperoxide bridge essential for activity. The main mechanism of action of ARS and its derivatives (artesunate, dihydroartemisinin, artemether) toward leukemia, multiple myeloma, and lymphoma cells comprises oxidative stress response, inhibition of proliferation, induction of various types of cell death as apoptosis, autophagy, ferroptosis, inhibition of angiogenesis, and signal transducers, as NF-κB, MYC, amongst others. Therefore, new pharmaceutically active compounds, dimers, trimers, and hybrid molecules, could enhance the existing therapeutic alternatives in combating hematologic malignancies. Owing to the high potency and good tolerance without side effects of ARS-type drugs, combination therapies with standard chemotherapies could be applied in the future after further clinical trials in hematological malignancies.

Trends in Crossover of Patients in Phase III Clinical Trials for Hematologic Malignancies

Background: The incorporation of crossover in randomized controlled trials is accepted as an ethical obligation, especially in cancer clinical trials. The more common type of crossover is unidirectional, which allows patients assigned to the control arm (either placebo or standard of care) to switch to the experimental arm. In contrast, bidirectional crossover includes the switching of patients from the experimental arm to the control arm. Integrating crossover into the initial study design may have advantages in patient recruitment, and incorporating crossover after initial positive results fulfills ethical requirements. However, crossover can also contribute to confounding major endpoints of studies, such as overall survival or the second progression-free survival interval. For this reason, it is important to investigate and identify potential trends of crossover in clinical trials testing novel therapies. The development of new treatments for hematologic malignancies is promising, and as such, makes these trials susceptible to crossover. Trends in crossover of clinical trials for hematologic malignancies have not yet been studied. Methods: Data about cancer clinical trials were extracted from clinicaltrials.gov. The search query was limited to completed phase III studies in adult populations. Location was limited to the United States. No date range or funder type was specified. The following search query was used: recruitment status: "completed;" age: "adult (18-64)," "older adult (65+);" sex: "all;" country: "United States;" study phase: "phase 3." These criteria were then applied in individual searches for clinical trials related each hematologic malignancy. The following terms were used in the "disease" search field: "acute lymphoid leukemia," "acute myeloid leukemia," "multiple myeloma," "lymphoma," "chronic myeloid leukemia," and "chronic lymphocytic leukemia." Repeat clinical trials obtained through separate searches were excluded. Studies were then excluded if they were not randomized controlled trials (RCTs) with the primary purpose of treatment, and if they did not test cancer-related interventions. Results: A total of 184 unique clinical trials were identified, of which 156 were RCTs with the primary purpose of treatment. Only 149 trials tested cancer-related drugs, biologicals, or procedures. Of those, 60 trials contained 2 experimental arms, and 89 trials contained 3 or more experimental arms. 6 of the 60 (10%) 2 arm trials permitted crossover, and 4 of the 89 (4.5%) 3+ arm trials permitted crossover, for a total of 10 trials with crossover. The start dates of these trials ranged from 2000-2012. 3 trials (30%) were bidirectional, and 7 (70%) were unidirectional. The identified clinical trials with crossover belonged to only 3 of the original 6 hematologic malignancies included in the original search query: multiple myeloma, lymphoma, and CML (Table 1). Conclusions: The proportion of identified clinical trials with crossover to those without is extremely small. Crossover in clinical trials studying hematologic malignancies does not appear to be a widespread practice. Multiple myeloma contains the most trials with crossover compared to other hematologic malignancies. Even though statistical approaches to mitigate confounding exist, crossover can still skew accurate reporting of the impact of experimental therapies on overall survival. Examining trends among the trials with crossover will hopefully lead to improved correction methods and better estimates of treatment benefit. Disclosures No relevant conflicts of interest to declare.

Perceptions of Community Hematologists/Oncologists on Barriers to Chimeric Antigen Receptor T-Cell Therapy for the Treatment of Diffuse Large B-Cell Lymphoma

Introduction The ASH Annual Meeting is a venue for presentation of outcomes data from key clinical trials in hematologic malignancies and novel drug classes used to treat them. The approval of two CAR-T therapies, axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tis-cel), in the treatment of large B-cell lymphoma (LBCL), including diffuse LBCL (DLBCL), has ushered in a new class of drugs, i.e. cellular therapy. At ASH 2018, Nastoupil et al. presented data from a retrospective analysis of the characteristics and outcomes of patients with relapsed/refractory LBCL, including DLBCL, treated with commercially available axi-cel CAR-T therapy at academic centers in the United States (Nastoupil LJ, et al. Blood. 2018;132[Suppl 1]:91). The authors found that early outcomes of real-world patients receiving axi-cel therapy were comparable to those observed in the clinical trial population, despite &gt;40% of these patients failing to meet the clinical trial eligibility criteria. At a live meeting in February 2019, we sought the perceptions of community hematologists and oncologists (H/O) regarding their use of, referrals for and barriers to CAR-T therapy as well their perception of the value of the real-world evidence (RWE) presented. Methods A live meeting in February 2019 convened H/O with geographic representation from across the United States. The participants were shown data from selected oral and/or poster presentations from the 2018 ASH Annual Meeting and responded to questions regarding their perceptions of the data and its potential impact on current practice. Participants submitted their demographic responses via a web-based survey prior to the meeting and data impression responses via an audience response system at the live meeting. Results Among the 59 H/O who participated in this live market research program on February 22-23, 2019, 61% identified their primary specialty as hematology/oncology and 34% medical oncology. Only 27% of H/O had attended the 60th ASH Annual Meeting in December 2018. The participants were mostly community-based physicians, 50% in private community and 45% in community practices owned by a hospital or academic center. One-third have been in practice for over 20 years, one-third for 11-20 years and one-third for 10 or fewer years. This group sees an average of 20+ patients per day and reported B-cell non-Hodgkin lymphoma as one of the three most common hematologic malignancy they managed. 28% of H/O indicated that they have referred one patient and 24% have referred 2-5 patients for CAR-T therapy since the first approval on August 30, 2017. Of those H/O who had referred patients for CAR-T therapy, 45% indicated that none of their patients had yet received the infusion. The top two barriers to prescribing/recommending CAR-T therapy, as reported by the H/O, were the cumbersome logistics of administering therapy and following patients (52%), and the cost of the therapy (46%). Other concerns included high toxicity (24%) and lack of long-term survival data (19%), but not lack of knowledge of CAR-T therapy (2%). Furthermore, 87% of H/O agreed with the assertion that due to the limitations of randomized clinical trials, RWE is necessary to inform clinical practice. After review of the information presented on the real-world use of axi-cel, 73% of H/O indicated that this information is likely to cause them to recommend CAR-T therapy for more of their patients with DLBCL. Conclusions There is significant interest in adopting and using CAR-T therapies in LBCL amongst community H/O. This group does not perceive itself as lacking in knowledge regarding CAR-T therapy. The significant barriers of logistics and cost are potential deterrents to appropriate use. These results can inform stakeholders (manufacturers, payers, hospitals and practices) regarding the need to improve processes and develop payment models to address cost in order to facilitate access of these agents to the appropriate patients. RWE is viewed favorably by the vast majority of community H/O to inform clinical practice, due to the limitations of randomized clinical trials. Disclosures Gajra: Cardinal Health: Employment. Sweat:Cardinal Health: Employment. Jeune-Smith:Cardinal Health: Employment. Kish:Cardinal Health: Employment. Feinberg:Cardinal Health: Employment.

Patterns of substrate affinity, competition, and degradation kinetics underlie biological activity of thalidomide analogs

AbstractPharmacologic agents that modulate ubiquitin ligase activity to induce protein degradation are a major new class of therapeutic agents, active in a number of hematologic malignancies. However, we currently have a limited understanding of the determinants of activity of these agents and how resistance develops. We developed and used a novel quantitative, targeted mass spectrometry (MS) assay to determine the relative activities, kinetics, and cell-type specificity of thalidomide and 4 analogs, all but 1 of which are in clinical use or clinical trials for hematologic malignancies. Thalidomide analogs bind the CRL4CRBN ubiquitin ligase and induce degradation of particular proteins, but each of the molecules studied has distinct patterns of substrate specificity that likely underlie the clinical activity and toxicities of each drug. Our results demonstrate that the activity of molecules that induce protein degradation depends on the strength of ligase-substrate interaction in the presence of drug, the levels of the ubiquitin ligase, and the expression level of competing substrates. These findings highlight a novel mechanism of resistance to this class of drugs mediated by competition between substrates for access to a limiting pool of the ubiquitin ligase. We demonstrate that increased expression of a nonessential substrate can lead to decreased degradation of other substrates that are critical for antineoplastic activity of the drug, resulting in drug resistance. These studies provide general rules that govern drug-dependent substrate degradation and key differences between thalidomide analog activity in vitro and in vivo.

Generation of CAR-T Cells for Cancer Immunotherapy.

T cells engineered with chimeric antigen receptors (CARs) are emerging as powerful cancer immunotherapies. Remarkable efficacies have been demonstrated in treating B-cell malignancies with CAR-T cells, leading to the FDA's first approval of gene therapy. Currently, numerous clinical trials for hematological malignancies and solid tumors are underway worldwide. Production of CAR-T cells with proper qualities is essential for CAR-T success in vivo. Here we detail optimized protocols for the generation of CAR-T cells for preclinical studies using lentiviral gene transfer, expansion of CAR-T cells in culture, detection of CAR expression, and evaluation of CAR-T cellular cytotoxicity in vitro.

A call to action in hematologic disorders: A report from the ASH scientific workshop on hematology and aging.

The American Society of Hematology (ASH) has recently promoted efforts to advance the intersection of hematology and aging by sponsoring an annual Scientific Friday Workshop on Hematology and Aging [ [1] http://www.hematology.org/Annual-Meeting/Program/Friday-Scientific-Workshops.aspx Google Scholar ]. Hematologic disorders, both malignant and benign, are highly prevalent among older adults [ 2 Howlader N.N.A. Krapcho M. Miller D. Bishop K. Kosary C.L. Yu M. Ruhl J. Tatalovich Z. Mariotto A. Lewis D.R. Chen H.S. Feuer E.J. Cronin K.A. SEER Cancer Statistics Review, 1975–2014. National Cancer Institute, Bethesda, MDJanuary 2018 Google Scholar , 3 McLean E. Cogswell M. Egli I. Wojdyla D. de Benoist B. Worldwide prevalence of anaemia, WHO vitamin and mineral nutrition information system, 1993–2005. Public Health Nutr. 2009; 12: 444-454 Crossref PubMed Scopus (1367) Google Scholar , 4 Smith B.D. Smith G.L. Hurria A. Hortobagyi G.N. Buchholz T.A. Future of cancer incidence in the United States: burdens upon an aging, changing nation. J Clin Oncol. 2009; 27: 2758-2765 Crossref PubMed Scopus (1318) Google Scholar ]. Despite the disproportionate burden of hematologic disease among older adults [ 2 Howlader N.N.A. Krapcho M. Miller D. Bishop K. Kosary C.L. Yu M. Ruhl J. Tatalovich Z. Mariotto A. Lewis D.R. Chen H.S. Feuer E.J. Cronin K.A. SEER Cancer Statistics Review, 1975–2014. National Cancer Institute, Bethesda, MDJanuary 2018 Google Scholar , 3 McLean E. Cogswell M. Egli I. Wojdyla D. de Benoist B. Worldwide prevalence of anaemia, WHO vitamin and mineral nutrition information system, 1993–2005. Public Health Nutr. 2009; 12: 444-454 Crossref PubMed Scopus (1367) Google Scholar , 4 Smith B.D. Smith G.L. Hurria A. Hortobagyi G.N. Buchholz T.A. Future of cancer incidence in the United States: burdens upon an aging, changing nation. J Clin Oncol. 2009; 27: 2758-2765 Crossref PubMed Scopus (1318) Google Scholar , 5 Bron D. Ades L. Fulop T. Goede V. Stauder R. Elderly task force in hematology ES. Aging and blood disorders: new perspectives, new challenges. Haematologica. 2015; 100: 415-417 Crossref PubMed Scopus (20) Google Scholar ], research studying the implications of age across the translational spectrum remains limited older adults understudied [ 6 Kanapuru Bindu Singh Harpreet Myers Adrian Beaver Julia A. Kwitkowski Virginia Elaine Farrell Ann T. et al. Enrollment of Older Adults in Clinical Trials Evaluating Patients with Hematologic Malignancies – the Food and Drug Administration (FDA). ASH, 2017 Google Scholar , 7 Cherubini A. Pierri F. Gasperini B. et al. Are ongoing trials on hematologic malignancies still excluding older subjects?. Haematologica. 2013; 98: 997-1000 Crossref PubMed Scopus (15) Google Scholar , 8 Hamaker M.E. Stauder R. van Munster B.C. Exclusion of older patients from ongoing clinical trials for hematological malignancies: an evaluation of the National Institutes of Health Clinical Trial Registry. Oncologist. 2014; 19: 1069-1075 Crossref PubMed Scopus (65) Google Scholar ]. The lack of pre-clinical aging models, dearth of translational efforts across diseases, and under-enrollment of older adults in clinical trials result in substantial gaps in knowledge. Understanding the interface of human aging and hematologic disorders in a growing population of older adults is warranted. Here we outline the progress to date spearheaded by the ASH community dedicated to hematology and aging.