Trials In Chronic Lymphocytic Leukemia Research Articles

End Point Surrogacy in First-Line Chronic Lymphocytic Leukemia.

Surrogate end points are commonly used to estimate treatment efficacy in clinical studies of chronic lymphocytic leukemia (CLL). This patient- and trial-level analysis describes the correlation between progression-free survival (PFS) and minimal residual disease (MRD) with overall survival (OS) in first-line trials for CLL. First, patient-level correlation was confirmed using source data from 12 frontline German CLL Study Group (GCLLSG)-trials. Additionally, a joint-frailty copula model was fitted to validate correlation in the setting of targeted therapies (TT). Second, a meta-analysis of first-line phase III trials in CLL from 2008 to 2024 was performed. Treatment effect correlation was quantified from seven GCLLSG and nine published trials, using hazard ratios (HRs) for time-to-event and odds ratios for binary end points. The GCLLSG analysis set comprised 4,237 patients. Patient-level correlation for PFS/OS was strong with Spearman Rho >0.9. The joint-frailty copula indicated a weak correlation for chemotherapy/chemoimmunotherapy (C/CIT) with a tau of 0.52 (95% CI, 0.49 to 0.55) while the correlation was strong for TT (tau, 0.91 [95% CI, 0.89 to 0.93). The meta-analysis set contained a total of 8,065 patients including 5,198 (64%) patients treated with C/CIT and 2,867 (36%) treated with TT. Treatment-effect correlation of the HRs for PFS and OS was R = 0.75 (95% CI, 0.74 to 0.76, R2 = 0.56) while correlation of end-of-treatment MRD with PFS and OS was R = 0.88 (95% CI, -0.87 to 0.89; R2 = 0.78) and 0.71 (95% CI, 0.69 to 0.73; R2 = 0.5), respectively. Patient-level correlation was confirmed in the setting of TTs while treatment-effect correlation between PFS and OS remains uncertain. MRD response status showed a high treatment-effect correlation with PFS but not OS, with the caveat of a limited number of randomized trials with available MRD data.

Transforming CLL management with immunotherapy: Investigating the potential of CAR T-cells and bispecific antibodies

Immunotherapies, such as chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies or T-cell engagers, have revolutionized the treatment landscape for various B-cell malignancies, including B-acute lymphoblastic leukemia and many non-Hodgkin lymphomas. Despite their significant impact on these malignancies, their application in chronic lymphocytic leukemia (CLL) management is still largely under investigation. Although the initial success of CD19-directed CAR T-cell therapy was observed in 3 multiply relapsed CLL patients, with 2 of them surviving over 10 years without relapse, recent CAR T-cell therapy trials in CLL have shown reduced response rates compared to their efficacy in other B-cell malignancies. One of the challenges with using immunotherapy in CLL is the compromised T-cell fitness from persistent CLL-related antigenic stimulation, and an immunosuppressive tumor microenvironment (TME). These challenges underscore a critical gap in therapeutic options for CLL patients intolerant or resistant to current therapies, emphasizing the imperative role of effective immunotherapy. Encouragingly, innovative strategies are emerging to overcome these challenges. These include integrating synergistic agents like ibrutinib to enhance CAR T-cell function and persistence and engineering newer CAR T-cell constructs targeting diverse antigens or employing dual-targeting approaches. Bispecific antibodies are an exciting "off-the-shelf" prospect for these patients, with their investigation in CLL currently entering the realm of clinical trials. Additionally, the development of allogeneic CAR T-cells and natural killer (NK) cells from healthy donors presents a promising solution to address the diminished T-cell fitness observed in CLL patients. This comprehensive review delves into the latest insights regarding the role of immunotherapy in CLL, the complex landscape of resistance mechanisms, and a spectrum of innovative approaches to surmount therapeutic challenges.

Impact of Baseline Comorbidities and Treatment on Cardiovascular (CV) Outcomes in Patients with Chronic Lymphocytic Leukemia (CLL): Results of a Systematic Literature Review (SLR) of Interventional Trials and a Targeted Literature Review (TLR) of Real-World Observational Studies in CLL

Background: Ibrutinib, the first Bruton tyrosine kinase inhibitor (BTKi) indicated for CLL, has been associated with a higher risk of CV events, including atrial fibrillation (AF) and hypertension, vs non-BTKi active comparators and placebo. In a phase 3 clinical trial of patients (pts) with CLL comparing ibrutinib with acalabrutinib-a more selective, second-generation BTKi-CV event incidence was numerically higher with ibrutinib and the incidence and cumulative risk of AF were significantly higher with ibrutinib (Byrd JC et al. J Clin Oncol. 2021;39:3441-52). Ibrutinib's toxicity profile prompted changes to its prescribing information and lowered its recommendation status in current CLL guidelines. We conducted an SLR of interventional trials in CLL followed by a supplemental TLR of observational studies in CLL to explore the extent to which CV outcomes of pts with CLL are driven by their baseline comorbidities or treatments. Methods: Embase and MEDLINE were searched to identify evidence in peer-reviewed journals (cutoff date: June 23, 2023). For the SLR, limits were English articles published in 2012 or later, and inclusion criteria specified phase 2/3 interventional trials in adults aged ≥18 y with treatment-naive or relapsed/refractory CLL. Treatments included BTKis, BCL-2 inhibitors, and chemoimmunotherapy. CV outcomes were arrhythmia, heart failure, major adverse CV events, major bleeding, myocardial infarction, stroke, sudden cardiac death, and venous thromboembolism. For the TLR, language and time limits were analogous to the SLR. Additional limits were observational studies with >70% CLL pts receiving any or no treatment. The TLR assessed baseline CV events/risk, including arrhythmia, heart failure, major adverse CV events, major bleeding, myocardial infarction, stroke, sudden cardiac death, and venous thromboembolism. Results: The SLR yielded 55 studies. Among the phase 3 randomized controlled trials, incidence ranges were 0%-16% for AF/atrial flutter, 0%-6.9% for heart failure, and 0%-11% for major bleeding; rates were generally higher with BTKis, among which ibrutinib appeared to be associated with the highest rates ( Figure 1). CV data from the SLR were sparse and heterogeneous, primarily due to limited baseline CV risk reporting and substantial variability in CV adverse event reporting. To clarify relationships of CV risk with treatment, we performed the TLR, which yielded 24 studies. Analysis of baseline CV risk reported in the observational studies yielded several key findings ( Figure 2): 1) in pts with CLL, the risk of CV events, including AF, increased with age; in pts aged 65−74 y and ≥65 y, the reported risk of AF was 2.4-fold and 2.8-fold higher, respectively, than that of pts aged <65 y (Shanafelt TD et al. Leuk Lymphoma. 2017;58:1630-9; Visentin A et al. Hematol Oncol. 2019;37:508-12); 2) baseline CV risk was similarly high in pts with CLL and matched non-CLL comparators (Larsson K et al. Am J Hematol. 2022;97:E255-7); 3) ibrutinib was associated with a higher risk of CV disease relative to chemotherapy, even when prior AF, age, and anticoagulant exposure were controlled for (Abdel-Qadir H et al. J Clin Oncol. 2021;39:3453-62). In ibrutinib-treated pts with a B-cell malignancy followed in cardio-oncology clinics (N=53; n=38 CLL), median time to new onset of ibrutinib-related AF was 5.5 mo; AF incidence was 15-fold higher in ibrutinib-treated pts overall vs that expected in an age- and sex-comparable general population and in ibrutinib-treated pts with CLL vs that expected in pts with CLL and no ibrutinib treatment (Baptiste F et al. Open Heart. 2019;6:e001049). Conclusions: CLL primarily affects the elderly, who are at higher risk of CV events vs a younger demographic. Results suggest that some pts with CLL have an increased risk of adverse CV outcomes; thus, it would be inaccurate to attribute the higher rates of CV events observed in pts with CLL solely to their treatment as it is plausible that pts with CLL already have an elevated CV risk contributing to such outcomes. However, our findings suggest that the first-generation BTKi (ibrutinib) may impact CV outcomes in these pts; data examining the CV risk of second-generation BTKis and other novel therapies (eg, venetoclax) are limited. Future research that consistently estimates baseline CV risk and closely monitors CV parameters in pts with CLL is required to ascertain the true risk of CV disease due to CLL treatment.

Association of Measurable Residual Disease with Progression-Free Survival in Patients with Chronic Lymphocytic Leukemia: A Systematic Review and Meta-Analysis in the Era of Novel Agents

Introduction: Achieving undetectable measurable residual disease (uMRD) following treatment has shown significant prognostic value in several hematological malignancies. In chronic lymphocytic leukemia (CLL), uMRD is associated with improved outcomes in the era of chemoimmunotherapy (CIT). However, the role of measurable residual disease (MRD) in the context of novel agents such as Bruton tyrosine kinase inhibitors (BTKi) and/or BCL2 inhibitors (e.g. venetoclax) is uncertain. To address this question, we conducted a systematic review of the literature and performed a comprehensive meta-analysis of trials that included novel agents to evaluate the association between MRD status after treatment and PFS in patients with CLL. Methods: We conducted a comprehensive search of PubMed, EMBASE, Scopus, and Web of Science focusing on CLL trials reporting MRD and its association with PFS. Results were independently screened by two reviewers. Inclusion criteria included prospective phase 3 trials involving a novel agent in one of the treatment arms, while studies with incomplete information on MRD status related to PFS, reviews, abstracts, and retrospective analyses were excluded. The initial search identified 185 studies in PubMed and 402 studies in EMBASE. After applying prespecified criteria, a total of 10 phase 3 trials were included in our analysis. We extracted sample size, patient age, follow-up time, time point and tissue of MRD assessment, MRD cut-off and rate, performance status and molecular status when available. We only considered treatment arms with complete MRD information. The comparison involved patients who achieved uMRD with those exhibiting detectable MRD. When available, hazard ratios (HR) and confidence intervals (CI) were used to evaluate the relationship between MRD status and PFS. If not, we used Kaplan-Meier (KM) curves from both uMRD and MRD subgroups and extracted the coordinates points of the curves using DigitizeIt software (version 2.5.10, I. Bormann) and using the number at risk provided we estimated the HRs and CIs. A meta-analysis was performed using a random effects model from the R package metafor (Viechtbauer, W. (2010). Conducting meta-analyses in R with the metafor package. Journal of Statistical Software, 36(3), 1-48). The pooled hazard ratio estimates, and the corresponding 95% CI and prediction intervals (PI) were reported. Funnel and Baujat plots were generated to assess study heterogeneity and bias. All analysis was performed using R version 4.1.2 (R Foundation for Statistical Computing, Vienna, Austria). Results: A total of 10 phase 3 trials, encompassing 14 treatment arms and involving 3152 patients, met the stringent inclusion criteria. All but one study used a uMRD cut-off of < 0.01%. Detailed information on the treatment arms and key trial characteristics is presented in Table 1. Notably, ten treatment arms were derived from first-line treatment trials, while the remaining arms pertained to the relapsed/refractory population. Only two trials (4 treatment arms) assessed MRD using next generation sequencing (NGS), while the rest used multicolor flow cytometry (MFC) (9 treatment arms) and allele-specific oligonucleotides polymerase chain reaction (ASO-PCR) (2 treatment arms). All but 3 trials assessed MRD in both bone marrow (BM) and peripheral blood (PB). One trial (2 treatment arms) was excluded from the met-analysis due to higher MRD cut-off. All studies included in the meta-analysis measured uMRD (<0.01) versus MRD. The PFS pooled HR estimate for achieving uMRD at 0.01 cut off from the meta-analysis was 0.32 (95% CI [0.22, 0.45]), with minimal bias observed on the Funnel Plot. Conclusions: In this comprehensive meta-analysis, comprising 9 phase 3 trials, achieving uMRD was strongly associated with PFS. These findings further establish the prognostic role of MRD in CLL management and its potential use as a surrogate marker in clinical trials. As the body of evidence on MRD in CLL continues to grow, it becomes imperative to standardize the optimal time point, methodology, and tissue for MRD assessment. Substantial heterogeneity in these aspects underscores the necessity for unified guidelines to ensure the accurate and consistent evaluation of MRD status in clinical practice.

Targeted Agents in Chronic Lymphocytic Leukemia (CLL): Advancements in Overall Survival Outcomes?

The impact of targeted agents (TAs) in fully mitigating the detrimental effects of CLL on overall survival (OS) remains uncertain. To address this, we compared the 5-year OS of treatment-naïve CLL pts who received targeted agents (TAs) in phase 3 clinical trials with the 5-year OS of age- and gender-matched general population (AGMGP) in Italy and the US. For this analysis, we included clinical trials that involved elderly or unfit pts (RESONATE2, ILLUMINATE, ALLIANCE, ELEVATE-TN, CLL14, and GLOW). We also considered trials enrolling fit pts eligible for FCR (Fludarabine, Cyclophosphamide, and Rituximab) treatment (ECOG1912, FLAIR, and CLL13). We used the method proposed by Liu et al. [BMC Med Res Methodol 2021;21(1):111] to reconstruct individual patient data (IPD) from published Kaplan-Meier survival curves. The expected OS rate for the control population was calculated using 2019 Italian data from the Istituto Nazionale di Statistica (ISTAT) and the 2019 US database. OS of CLL pts and AGMGP were compared for restricted mean overall survival time (RMOST). The treatment effect on OS was then measured as the difference of RMOST and expressed in months. The elderly CLL trial analysis group (2,222 pts) received TAs (58.1%) or chemo-(immunotherapy)(CT/CIT) (41.8%). TAs included Bruton Kinase inhibitors (BTKis) (i.e., ibrutinib [I] or acalabrutinib [A]) alone or with anti-CD20 (75%) or fixed-duration (FD) venetoclax [V] combos (25%). The control CT/CIT arm mainly consisted of CLB+Obinu (66%). The median age of pts was 70 years (range 47-93). The prevalence of del(17p)/mutated TP53, unmutated IGHV, or CIRS score>6 were 9.1% (0-16%), 62.4% (43-66.5%), and 48.6% (11.7-86.1%), respectively. In the aggregate analysis, the 5-year RMOST of elderly pts treated with CT/CIT (RESONATE2, ILLUMINATE, ALLIANCE, ELEVATE-TN, CLL14, and GLOW) was found to be inferior compared to the 5-year RMOST of Italian [Difference (D), -4.2 months; 95% CI: -5.3 to -3.0; P < 0.0001] and US [D, -3.6 months; 95% CI: -4.7 to -2.4; P < 0.001] AGMGP (Fig 1). The analysis of pts treated with TAs provided conflicting results. In the cross-matched comparison between Italian AGMGP and pts treated with BTKi single-agent or combined with anti-CD20, the 5-year RMOST difference indicates an OS advantage for the former (Fig 1). The same applied in the comparison between pts who received FD V-based therapies and Italian or US AGMGP. Notably, the 5-year RMOST of elderly CLL pts treated with BTKi single-agent (RESONATE2, ALLIANCE, ELEVATE-TN) or combined with anti-CD20 (ILLUMINATE, ALLIANCE, ELEVATE-TN) was similar to the 5-year RMOST of US AGMGP [D, -1.2 mo. (-2.5 to 0.1); P = 0.07 for both](Fig 1). OS comparisons between elderly CLL pts and control populations, although controlled for age and gender, do not account for the interaction between comorbidity burden and OS. The proportion of pts with CIRS score > 6 varied widely across trials: RESONATE2, 31%; ELEVATE-TN, 11.1% in the A-arm and 16.8% in the AO-arm; ILLUMINATE, 32.7%; CLL14, 86.1%; and GLOW, 69.0%. Since CLL pts eligible for FCR enrolled in the ECOG1912, FLAIR, and CLL13 trials typically have fewer comorbidities, they enable a clearer evaluation of the TA's impact on OS. Overall, 1,437 patients (64.5%) received TAs, and 789 (35.4%) received CIT. TAs consisted of I+R (51.5%) or FD V-based combinations (VO, VI, VO+Ibr) (48.5%). The median age of pts was 62 years (range 27-84). The prevalence of ECOG PS 0 and unmutated IGHV were 68% and 56%, respectively. The 5-year RMOST of younger/fit pts treated with FCR was inferior to the 5-year RMOST of Italian AGMGP [D, -1.1 mo; 95% CI: -1.8 to -0.3; P = 0.003] but similar to the 5-year RMOST of US AGMGP [D, -0.4 mo; 95% CI, -1.1 to 0.4; P = 0.28]. Interestingly, no significant difference could be observed between the 5-year RMOST of younger/fit pts treated with TAs (IR or Ven-based) and the 5-year RMOST of Italian or US AGMGP (Fig 2). In conclusion, our results suggest that in comparison to CIT, TAs mitigate but do not fully abrogate the detrimental impact of CLL on OS. The intricate interaction between CLL characteristics and the burden of comorbidities can potentially lead to misleading results in clinical trials of elderly pts. The extent of OS improvement obtained with TAs seems higher in younger/fit CLL pts who have fewer comorbidities. However, longer follow-up is needed to discern the ability of these treatments to mitigate the impact of CLL on OS over longer time intervals.

Endpoint Surrogacy in Chronic Lymphocytic Leukemia: A Pooled Analysis of the German CLL Study Group

Introduction Overall survival (OS) is generally considered the most patient-relevant endpoint in oncology trials, however, its implementation can entail several challenges in the context of chronic lymphocytic leukemia (CLL): 1) The competing survival risk due to comorbidities in the mostly elderly CLL patient population; 2) the high efficacy of targeted therapies warrant longer observation periods or extensive patient recruitment, which can be operationally challenging; 3) the interference with increasingly potent relapse therapies, which can neutralize differences of efficacy of first line regimen. Hence, surrogate endpoints, such as progression-free survival (PFS), overall response or complete response rate (ORR, CR) or minimal residual disease (MRD), are commonly used in CLL research. However, data supporting a correlation between surrogate endpoints and OS in the treatment for CLL is scarce. Here, we present a large, systematic analysis of over 4000 patients (pts) treated in studies of the German CLL Study Group (GCLLSG) to determine the adequacy of surrogate endpoints in clinical trials for pts with CLL. Methods We analysed twelve phase II and phase III trials of the GCLLSG spanning from 1999 to 2022. Only pts receiving first-line therapy were included in the analysis. To determine correlation, the Kaplan-Meier survival function was estimated for both OS and PFS for each study separately. From these functions, the probability of survival (OS and PFS) was estimated at different time points. These pairs of time points were then correlated across the studies, with each pair of probabilities weighted by the number of pts in each corresponding study using Spearman's correlation coefficients. Additionally, we compared OS according to MRD and iwCLL response status at end-of-treatment (for fixed-duration regimens) or end-of-induction-treatment (for MRD-guided treatments) (EO[I]T) using Kaplan-Meier functions calculated from the time point of MRD assessment in peripheral blood. EO(I)T ranged from month 9 to month 15 after treatment initiation, depending on the study protocol. Results The full analysis set comprised 4237 pts. The median observation time was 67 months. Median age was 64 years (range 27 - 90). 45.1% of pts were older than 65 years. 3159 pts (74.6%) had received chemo/chemoimmunotherapy (C/CIT), whereas 1078 (25.4%) were treated with targeted therapies. There were 2114 progressive disease (PD) events and 1211 deaths captured within the trial data. The Spearman's Rho of the estimated survival probabilities for the time points 12/24, 24/36, 36/48 and 60/72 months (PFS/OS) was 0.95, 0.96, 0.94 and 0.92, respectively ( Panel A). Focussing on pts with confirmed OS event (n=1211), the Spearman's Rho between PFS and OS in months was 0.66 for pts receiving chemo/chemoimmunotherapy and 0.88 for pts receiving targeted treatment. ORR and CR rate was 89.8% and 31.5%, respectively. Pts with a CR had a significantly longer PFS (HR 0.38, 95% CI 0.34-0.42, p <0.001) and OS (HR 0.39, 95% CI 0.33- 0.46, p <0.001) compared to pts with non-CR. MRD measurements at the EO(I)T were available for 2521 pts (59.5%), of which 39% were treated with targeted agents. Rates of undetectable (<10 -4), intermediate (≥10 -4 and <10 -2) and high MRD (≥10 -2) were 59.1%, 21.7%, 19.3%, respectively, across treatment groups. The median OS for undetectable and intermediate MRD was not reached and 60.7 months for high MRD status ( Panel B). The estimated 60-month OS was 84.6%, 71.3% and 51.1%, respectively. Accordingly, median PFS for uMRD was 61.8 months and 60-month PFS was 52.6%. In pts ≤65 years of age, median OS was not reached with undetectable or intermediate MRD and 70.5 months in pts with high MRD status. In pts >65 years, median OS was not reached for uMRD and was 75.2 and 58.8 months, respectively, for pts with intermediate or high MRD. The corresponding hazard ratios for high versus uMRD status at EO(I)T were 3.33 (95% CI 2.57 - 4.3) in older and 5.89 (4.15 - 8.35) in younger pts. Conclusion In this large analysis of 12 prospective CLL trials, we found a robust correlation between PFS and OS, thereby supporting the use of PFS as a surrogate endpoint in clinical studies. More importantly, the MRD status at EO(I)T was associated with OS across all treatment modalities, demonstrating its utility in identifying pts with potentially dismal outcomes and providing a rationale for MRD-guided treatment strategies.

Statistical Considerations and Software for Designing Sequential, Multiple Assignment, Randomized Trials (SMART) with a Survival Final Endpoint

ABSTRACT Sequential, multiple assignment, randomized trial (SMART) designs are appropriate for comparing adaptive treatment interventions, in which intermediate outcomes (called tailoring variables) guide subsequent treatment decisions for individual patients. Within a SMART design, patients may be re-randomized to subsequent treatments following the outcomes of their intermediate assessments. In this paper, we provide an overview of statistical considerations necessary to design and implement a two-stage SMART design with a binary tailoring variable and a survival final endpoint. A chronic lymphocytic leukemia trial with a final endpoint of progression-free survival is used as an example for the simulations to assess how design parameters, including, choice of randomization ratios for each stage of randomization, and response rates of the tailoring variable affect the statistical power. We assess the choice of weights from restricted re-randomization on data analyses and appropriate hazard rate assumptions. Specifically, for a given first-stage therapy and prior to the tailoring variable assessment, we assume equal hazard rates for all patients randomized to a treatment arm. After the tailoring variable assessment, individual hazard rates are assumed for each intervention path. Simulation studies demonstrate that the response rate of the binary tailoring variable impacts power as it directly impacts the distribution of patients. We also confirm that when the first stage randomization is 1:1, it is not necessary to consider the first stage randomization ratio when applying the weights. We provide an R-shiny application for obtaining power for a given sample size for SMART designs.

Oncogenic role and target properties of the lysine-specific demethylase KDM1A in chronic lymphocytic leukemia

AbstractIn chronic lymphocytic leukemia (CLL), epigenetic alterations are considered to centrally shape the transcriptional signatures that drive disease evolution and underlie its biological and clinical subsets. Characterizations of epigenetic regulators, particularly histone-modifying enzymes, are very rudimentary in CLL. In efforts to establish effectors of the CLL-associated oncogene T-cell leukemia 1A (TCL1A), we identified here the lysine-specific histone demethylase KDM1A to interact with the TCL1A protein in B cells in conjunction with an increased catalytic activity of KDM1A. We demonstrate that KDM1A is upregulated in malignant B cells. Elevated KDM1A and associated gene expression signatures correlated with aggressive disease features and adverse clinical outcomes in a large prospective CLL trial cohort. Genetic Kdm1a knockdown in Eμ-TCL1A mice reduced leukemic burden and prolonged animal survival, accompanied by upregulated p53 and proapoptotic pathways. Genetic KDM1A depletion also affected milieu components (T, stromal, and monocytic cells), resulting in significant reductions in their capacity to support CLL-cell survival and proliferation. Integrated analyses of differential global transcriptomes (RNA sequencing) and H3K4me3 marks (chromatin immunoprecipitation sequencing) in Eμ-TCL1A vs iKdm1aKD;Eμ-TCL1A mice (confirmed in human CLL) implicate KDM1A as an oncogenic transcriptional repressor in CLL which alters histone methylation patterns with pronounced effects on defined cell death and motility pathways. Finally, pharmacologic KDM1A inhibition altered H3K4/9 target methylation and revealed marked anti–B-cell leukemic synergisms. Overall, we established the pathogenic role and effector networks of KDM1A in CLL via tumor-cell intrinsic mechanisms and its impacts in cells of the microenvironment. Our data also provide rationales to further investigate therapeutic KDM1A targeting in CLL.

Abstract 1789: Pre-clinical studies to advance anti-ROR1 CAR-T cell therapy for metastatic prostate cancer

Abstract Background: Alterations in WNT signaling are frequently associated with tumorigenesis and metastasis in many cancers including prostate cancer (PCa). The Wnt ligand, WNT5A, is required for normal prostate gland development and is increased in bone metastatic, castration resistant PCa (CRPC) patients. WNT5A signaling is mediated in part through ROR1, a non-canonical Wnt receptor and fetal oncoprotein for which the therapeutic inhibitory antibody, Zilovertamab, has been developed. Its safety has been clinically proven in trials for chronic lymphocytic leukemia (CLL) and metastatic breast cancer. We sought to investigate Zilovertamab-based anti-ROR1 therapies for metastatic prostate cancer.Our Hypothesis is that WNT5A may activate a stem-cell-like program via ROR1 which leads to therapy resistance in metastatic prostate cancer. The anti-ROR1 biologic, Zilovertamab, may inhibit this mechanism of resistance. The expression of ROR1 on CRPC and NEPC tumors and its lack of expression on normal adult tissues makes it a promising CART cell target. Methods: We used the patient-derived xenograft (PDX), PCSD13, small cell bone metastatic prostate cancer model and the neuroendocrine PCa cell lines, PC3 and DU145, to test the effect of Zilovertamab and Zilovertamab-CART cells in vitro using the real time cell viability, proliferation, and cell cycle tracking assays in an Incucyte S3. We used in vivo bioluminescence and tumor caliper measurements to monitor effects in vivo. Results: Studies using RNASeq, qRT-PCR, FACS and Westerns showed high expression of ROR1 in PC3, DU145, and in PCSD13. CRISPR-Cas9 Knock out of ROR1 in PC3 and DU145 cells showed increased inhibition of proliferation at lower docetaxel concentrations. Treatment of PCSD13 PDX in vivo with Zilovertamab increased docetaxel-mediated tumor growth inhibition. Mice bearing PC3 xenografts injected intravenously with Zilovertamab anti-ROR1 CAR-T cells showed durable, tumor ablation in 67% of mice compared to 22% of mice injected with activated T cells from the same donor and 0% of untreated mice. Survival of mice at Day 70 injected with CART was 78% compared to 0% of mice injected with control donor T cells and 0% of untreated mice. Zilovertamab antibody could inhibit Zilovertamab CART cell tumor cell killing. Conclusions: ROR1 was expressed at high levels on castration resistant small cell PCa and neuroendocrine PCa cell lines and PDX models. Zilovertamab synergized with docetaxel to inhibit tumor growth in patient derived xenograft in vivo and in organoid cultures. Zilovertamab-based CART cells durably eradicated ROR1+ prostate cancer xenograft tumors. These studies supported the recently launched Phase 1b clinical trial of Zilovertamab plus docetaxel in metastatic CRPC patients. Clinical development of GMP Zilovertamab CART cells for a clinical trial in CLL is in progress and may lead to rapid progression to a clinical trial for metastatic CRPC and NEPC. Citation Format: Christina A.M. Jamieson, Jamillah Murtadha, Christopher S. Oh, Michelle Muldong, Evodie Koutouan, JOngwook Kim, Niloofar Etemadfard, Hae Soo Choo, Navyaa Sinha, Sanghee Lee, Christina Wu, Gabriel Pineda, Kathleen Lennon, Karl Willert, Catriona H. Jamieson, Terry Gaasterland, Rana Mckay, Christopher J. Kane, Thomas J. Kipps, Anna A. Kulidjian, Nicholas A. Cacalano, Charles Prussak. Pre-clinical studies to advance anti-ROR1 CAR-T cell therapy for metastatic prostate cancer [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 1789.

PD04-10 PRE-CLINICAL STUDIES TO ADVANCE ZILOVERTAMAB-BASED ANTI-ROR1 DUAL SPECIFICITY CAR T-CELL THERAPY FOR METASTATIC PROSTATE CANCER.

PD04-10 PRE-CLINICAL STUDIES TO ADVANCE ZILOVERTAMAB-BASED ANTI-ROR1 DUAL SPECIFICITY CAR T-CELL THERAPY FOR METASTATIC PROSTATE CANCER.

Quality of Control Arms in Randomized Trials of Chronic Lymphocytic Leukemia Enrolling in the USA: A Systematic Review

Introduction: Many ongoing clinical trials in chronic lymphocytic leukemia (CLL) are investigating "chemotherapy-free” combinations of novel agents administered in a time-limited manner both in the frontline and relapsed/refractory setting. However, there is a concern that the results of trials testing these novel treatment combinations can be difficult to interpret if the therapy in the control groups is suboptimal and/or are not commonly used in the USA. A suboptimal control group reduces the trial's external validity as it introduces a bias in favor of the experimental arm. To date, an empirical evaluation of the quality of control groups in randomized trials of chronic lymphocytic leukemia has not been undertaken. We sought to carry out a systematic review of randomized trials of CLL between Jan 2010 and Dec 2021 to establish the quality of the control group therapies compared to USA standards as determined by NCCN and expert reviews. Methods: PubMed (MEDLINE), Embase, Cochrane, Scopus, and Web of Science were searched for articles of randomized trials of CLL that enrolled participants in the USA between January 1, 2010, to December 31, 2021. Standard-of-care therapy for the USA was determined by evaluating the literature (expert reviews) and published guidelines (mainly NCCN) prior to the start of trial enrollment. The percentage of randomized trials that used suboptimal control arms was then calculated. A control group therapy was considered suboptimal if the choice of control arm was restricted (i.e., excluded an active therapy), and/or if prior randomized trials had shown the control agent (or class) was inferior to an available alternative or by limiting combinations in the control group. Results: A total of 1775 articles with our initial search strategy. 625 records were duplicates and were excluded. We screened 1150 articles in our primary screening. Of these, 156 were excluded due to being non-CLL studies, 117 records were excluded due to being duplicates, abstracts, trials in progress, and subgroup analysis, 258 records were excluded due to being review articles, and case series/reports, 564 records were excluded due to being single-arm studies. 55 articles were eligible for secondary screening. Of these, 29 did not meet inclusion criteria due to not enrolling in the U.S and 7 were excluded due to enrollment start date before Jan 2010. 19 trails were eligible for the final analysis. Of the 19 trials that were assessed in the final analysis, we identified 10 (52%) trials that enrolled patients in a suboptimal control arm. When classified further by the nature of the suboptimal control arm, 7 (36%) trials omitted active treatment in the control arm by using a control agent known to be inferior to other available agents or not allowing combinations, and 3 (16%) trials omitted active treatment in control arm by limiting investigator's choice. Conclusion: Our findings show that half of randomized trials of CLL use a suboptimal control group. Although limiting investigator choice is common within the context of a randomized trial and may not be detrimental, approx. a third of randomized trials use control agents that are known to be inferior to other available agents. The choice of control arm of trials enrolling in the USA should be optimized to ensure that it matches what most clinicians would prescribe outside a clinical trial setting. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Value of assessing liver enlargement as a group a parameter in chronic lymphocytic leukemia (CLL) clinical trials: Retrospective review of data from multiple trials for incidence of liver enlargement and impact on response assessment.

e19517 Background: iwCLL 2018 criteria defines liver enlargement as one of the important group A parameters for staging and overall response assessment (ORA). However, the authors acknowledge that given the impact of numerous medical conditions, liver size by physical examination or CT scan is not a reliable measure of hepatic involvement by CLL and should only be considered if hepatomegaly is clearly attributable to lymphoid involvement. The criteria even define partial response and progression categories as 50% decrease or increase, respectively, but no specific size or other criteria for assessing lymphoid involvement are proposed. Focal lesions in liver may be a sign of involvement by CLL but are assessed separately, as extranodal disease. Hepatomegaly may be non-specific with possible causes including metabolic, infectious, neoplastic, toxic, hereditary, vascular, and miscellaneous other causes. 20-30% of a general population may have non-alcoholic fatty liver enlargement. In the literature hepatomegaly by palpation has been defined as a portion of the liver below the costal margin and the cut-off for normal liver on imaging is considered < 16 cm in mid-clavicular line. However, there are various anatomic variations with no consensus on the size criteria for liver enlargement. Methods: Independent review data from seven phase II/III CLL trials for frontline therapies as well as in relapsed/refractory setting, were retrospectively analyzed. Data included the independent review assessment results of a total of 22224 timepoints (TPs) of 2223 subjects (2223 baseline (BL) and 20001 post-BL TPs). The data were analyzed for the incidence of subjects with liver enlargement at baseline, post-BL assessment of liver and its impact on ORA. Liver assessment in all trials was qualitative, and the criteria for enlargement was based on the reviewer’s judgement; no size limit was defined. Results: Only 7 out of 2223 subjects (0.3%) had liver enlargement at baseline. Liver assessment of these subjects at post-BL did not cause an upgrade or downgrade of the ORA. None of the 2223 subjects had liver progression at post-BL TPs. Conclusions: Based on the data analysis of a large sample size, it is evident that assessment of liver enlargement as a group A parameter in CLL clinical trials, does not impact the ORA. Liver is rarely even assessed as enlarged by independent reviewers, since hepatomegaly may be caused by various other medical conditions besides CLL. No size or other criteria help distinguish between liver enlargement from CLL versus other causes. We recommend removing liver enlargement as a group A parameter for response assessment as it complicates the assessment paradigm without adding any value to it. Liver involvement should only be assessed for focal lesions, as extranodal disease.

PD07-04 PRE-CLINICAL STUDIES FOR ADVANCING CIRMTUZUMAB-BASED ANTI-ROR1 THERAPIES IN METASTATIC PROSTATE CANCER

You have accessJournal of UrologyCME1 May 2022PD07-04 PRE-CLINICAL STUDIES FOR ADVANCING CIRMTUZUMAB-BASED ANTI-ROR1 THERAPIES IN METASTATIC PROSTATE CANCER Michelle Muldong, Sanghee Lee, Theresa Mendoza, Danielle Burner, Christina Wu, Jamillah Murtadha, Evodie Koutouan, Naomi Pineda, Gabriel Pineda, Kathleen Lennon, Hao Pham, Karl Willert, Nicholas Cacalano, Catriona Jamieson, Terry Gaasterland, Christopher Kane, Anna Kulidjian, and Christina Jamieson Michelle MuldongMichelle Muldong More articles by this author , Sanghee LeeSanghee Lee More articles by this author , Theresa MendozaTheresa Mendoza More articles by this author , Danielle BurnerDanielle Burner More articles by this author , Christina WuChristina Wu More articles by this author , Jamillah MurtadhaJamillah Murtadha More articles by this author , Evodie KoutouanEvodie Koutouan More articles by this author , Naomi PinedaNaomi Pineda More articles by this author , Gabriel PinedaGabriel Pineda More articles by this author , Kathleen LennonKathleen Lennon More articles by this author , Hao PhamHao Pham More articles by this author , Karl WillertKarl Willert More articles by this author , Nicholas CacalanoNicholas Cacalano More articles by this author , Catriona JamiesonCatriona Jamieson More articles by this author , Terry GaasterlandTerry Gaasterland More articles by this author , Christopher KaneChristopher Kane More articles by this author , Anna KulidjianAnna Kulidjian More articles by this author , and Christina JamiesonChristina Jamieson More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002526.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Increased levels of the Wnt ligand, WNT5A, are correlated with bone metastatic, castrate resistant PCa (CRPC). Wnt signaling is comprised of canonical (β-catenin dependent) and noncanonical pathways which are critical for normal development and physiology. Alterations are frequently associated with tumorigenesis and metastasis in many cancers including prostate cancer. Noncanonical Wnt5A signaling is mediated in part through ROR1, a fetal oncoprotein for which a therapeutic ROR1 inhibitory antibody, Cirmtuzumab, has been developed. Its safety has been clinically proven in trials for chronic lymphocytic leukemia (CLL) and metastatic breast cancer.Hypothesis: WNT5A may activate a stem-cell-like program via ROR1 that leads to castration resistance in bone metastatic prostate cancer. The anti-ROR1 biologic, Cirmtuzumab, may inhibit this mechanism of CRPC and re-sensitize bone metastatic prostate cancer to standard of care therapies. METHODS: We used patient-derived xenograft (PDX) bone metastatic prostate cancer models and PCa cell lines to test mechanism of action of a new therapeutic target, the WNT5A/ROR1 signaling pathway in prostate cancer for which a therapeutic ROR1 inhibitor antibody, Cirmtuzumab, has been developed and clinically tested in CLL and metastatic breast cancer patients. RESULTS: Preclinical studies using RNASeq, qRT-PCR, FACS and Westerns showed increased expression of ROR1 in the neuroendocrine prostate cancer cell lines, PC3 and DU145, and a patient derived xenograft (PDX) model of small cell bone metastatic prostate cancer, PCSD13. Pretreatment of the PCSD13 PDX with Cirmtuzumab increased the efficacy of the taxane docetaxel at inhibiting tumor growth. Intravenous infusion of anti-ROR1 CAR-T cells into mice bearing subcutaneous, ROR1-expressing, PC3 xenografts, showed marked reduction in tumor growth. ROR1 Knock out using CRISPR-Cas9 in PC3 and DU145 cells showed specificity of Cirmtuzumab-based immunotherapies. We have developed immunohistochemistry (IHC) assays to detect ROR1 in patient biopsy samples which will allow us to define the prostate cancer patient population that expressed ROR1 and to be able to evaluate the treatment in patients for a future clinical trial. CONCLUSIONS: ROR1 was expressed at high levels on castration resistant small cell PCa and neuroendocrine PCa models in PCa cell lines and PDX models. Cirmtuzumab has demonstrated efficacy in our patient derived xenograft organoid cultures. These studies have formed the rationale for development of a Phase 1b clinical trial of Cirmtuzumab in combination with docetaxel in metastatic CRPC patients. Source of Funding: Dept of Defense CDMRP PCRP Impact Award, JM Foundation © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e99 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Michelle Muldong More articles by this author Sanghee Lee More articles by this author Theresa Mendoza More articles by this author Danielle Burner More articles by this author Christina Wu More articles by this author Jamillah Murtadha More articles by this author Evodie Koutouan More articles by this author Naomi Pineda More articles by this author Gabriel Pineda More articles by this author Kathleen Lennon More articles by this author Hao Pham More articles by this author Karl Willert More articles by this author Nicholas Cacalano More articles by this author Catriona Jamieson More articles by this author Terry Gaasterland More articles by this author Christopher Kane More articles by this author Anna Kulidjian More articles by this author Christina Jamieson More articles by this author Expand All Advertisement PDF DownloadLoading ...

Targeting Mcl-1 by AMG-176 During Ibrutinib and Venetoclax Therapy in Chronic Lymphocytic Leukemia.

B-cell receptor (BCR) signaling pathway and Bcl-2 family prosurvival proteins, specifically Bcl-2 and Mcl-1, are functional in the pathobiology of chronic lymphocytic leukemia (CLL). A pivotal and apical molecule in the BCR pathway is Bruton’s tyrosine kinase (BTK). Together, BTK, Bcl-2, and Mcl-1 participate in the maintenance, migration, proliferation, and survival of CLL cells. Several ongoing and published clinical trials in CLL reported high rates of remission, namely, undetectable measurable residual disease (u-MRD) status with combined BTK inhibitor ibrutinib and Bcl-2 antagonist, venetoclax. While the majority of patients achieve complete remission with undetectable-measurable residual disease, at least one third of patients do not achieve this milestone. We hypothesized that cells persistent during ibrutinib and venetoclax therapy may be sensitive to combined venetoclax and Mcl-1 inhibitor, AMG-176. To test this hypothesis, we took peripheral blood samples at baseline, after Cycle 1 and Cycle 3 of ibrutinib monotherapy, after one week and 1 cycle of ibrutinib plus venetoclax therapy. These serial samples were tested for pharmacodynamic changes and treated in vitro with AMG-176 or in combination with venetoclax. Compared to C1D1 cells, residual cells during ibrutinib and venetoclax treatment were inherently resistant to endogenous cell death. Single agent exposure induced some apoptosis but combination of 100 nM venetoclax and 100 or 300 nM of AMG-176 resulted in 40–100% cell death in baseline samples. Cells obtained after four cycles of ibrutinib and one cycle of venetoclax, when treated with such concentration of venetoclax and AMG-176, showed 10–80% cell death. BCR signaling pathway, measured as autophosphorylation of BTK was inhibited throughout therapy in all post-therapy samples. Among four anti-apoptotic proteins, Mcl-1 and Bfl-1 decreased during therapy in most samples. Proapoptotic proteins decreased during therapy. Collectively, these data provide a rationale to test Mcl-1 antagonists alone or in combination in CLL during treatment with ibrutinib and venetoclax.

Real-World Efficacy of Venetoclax-Based Regimens in Patients with Chronic Lymphocytic Leukemia in Israel: A Multicenter Prospective Study

Real-World Efficacy of Venetoclax-Based Regimens in Patients with Chronic Lymphocytic Leukemia in Israel: A Multicenter Prospective Study

Time to Next Treatment, Healthcare Resource Utilization, and Healthcare Costs Among Patients with Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma Following First-Line Ibrutinib

Background: Ibrutinib is an oral once-daily Bruton's tyrosine kinase inhibitor (BTKi) and is the only targeted treatment that has demonstrated significant progression-free survival (PFS) and overall survival (OS) benefit in multiple phase 3 trials for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). With ibrutinib established as a preferred first-line (1L) treatment option, it is important to better understand the treatment sequence after 1L ibrutinib and the characteristics of patients who are treated with a second-line (2L) therapy. Using a real-world US administrative claims database, this study aimed to compare time to next treatment (TTNT), healthcare resource utilization (HRU), and healthcare costs between different 2L treatment regimens (cohorts) used after ibrutinib.Methods: Adults with CLL/SLL treated with 1L ibrutinib were identified in a US claims database (Optum's de-identified Clinformatics ® Data Mart Database; 02/12/2013-03/31/2020). Those receiving a 2L therapy were considered eligible for the study. Retreatment with ibrutinib, in-class switch to another BTKi, or treatment with anti-CD20 immunotherapy-only were not considered eligible 2L treatment options for this evaluation. The most commonly used treatment regimens were categorized into the following clinically-relevant treatment cohorts: 1) chemoimmunotherapy (CIT) or chemotherapy (CT)-only, and 2) venetoclax (VEN)- or idelalisib (IDELA)-based regimens (monotherapy or combination regimens). Comparisons of TTNT, HRU (inpatient admissions, outpatient visits, emergency room visits, other ancillary services), and per patient per month healthcare costs (inpatient admissions, outpatient visits, emergency room visits, other ancillary services, pharmacy) were evaluated based on the sum of the payer and patient paid amount during 2L treatment. Comparisons were adjusted using multivariate regression including confounders observed in the baseline period and during 1L ibrutinib therapy. For costs and HRU, 95% confidence intervals and p-values were obtained from 499 bootstrap resamples.Results: A total of 132 CLL/SLL patients who received ibrutinib as a 1L treatment and had a subsequent eligible 2L therapy were included; mean age was 74 years old, 64% were male. Eligible patients received 2L CIT/CT-only (63/132, 48%), or VEN/IDELA-based regimens (69/132, 52%). TTNT was significantly longer for 2L VEN/IDELA-based regimens than for CIT/CT (hazard ratio at 12 months: 0.37; P=0.0337) (Figure 1). The number of outpatient visits for antineoplastic drug administration was significantly lower for patients receiving 2L VEN/IDELA-based regimens compared to CIT/CT (rate ratio=0.44; P=0.004). Total mean monthly healthcare cost (includes CLL/SLL and non-CLL/SLL-related medical/pharmacy costs) was $1,754 higher, but not significantly different (P=0.593), for patients receiving VEN/IDELA-based regimens compared with CIT/CT (Figure 2). Total mean monthly medical cost (non-pharmacy) was significantly lower ($-5,202; P=0.036) for patients receiving VEN/IDELA-based regimens compared to CIT/CT (Figure 2).Conclusions: This study demonstrates that VEN/IDELA-based regimens may be a more viable treatment option post-1L ibrutinib use for CLL/SLL patients compared to CIT/CT. When compared to 2L CIT/CT, use of VEN/IDELA-based regimens post-1L ibrutinib use was associated with significantly longer TTNT and lower medical costs, signifying reduced disease burden to the patients and lessened burden to the healthcare system. These findings also suggest that treatment convenience associated with 2L oral targeted regimens may play an important role in improving treatment outcomes. These results support the need for evaluating treatment sequencing strategies in the real-world setting to further improve clinical outcomes and reduce the burden of total cost of care for patients with CLL/SLL. [Display omitted] DisclosuresChallagulla: Pharmacyclics LLC, an AbbVie Company: Current Employment; AbbVie: Current equity holder in publicly-traded company. Emond: Janssen: Consultancy; Novartis: Consultancy; Pfizer: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; GlaxoSmithKline: Consultancy. Volodarsky: Pharmacyclics LLC, an AbbVie Company: Current Employment; AbbVie: Current equity holder in publicly-traded company. Young: AbbVie: Current equity holder in publicly-traded company; Pharmacyclics LLC, an AbbVie Company: Current Employment. Manceur: AbbVie: Consultancy; Actelion, part of the Janssen Pharmaceutical Companies of Johnson & Johnson: Consultancy; Bristol-Myers Squibb: Consultancy; Daiichi-Sankyo: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy. Karve: AbbVie: Current Employment, Current equity holder in publicly-traded company.

Anti-CD37 Alpha-Amanitin Conjugated Antibodies As Therapeutic Weapons for Richter's Syndrome

The leukocyte surface antigen CD37 (TSPAN26), a member of the tetraspanin superfamily, is widely expressed on most malignant B cells, making it an actionable target for treatment of patients with chronic lymphocytic leukemia (CLL) and other B-cell non-Hodgkin lymphoma (NHL) indications. Accordingly, αCD37 antibodies have shown promising results in phase 1/2 clinical trials for CLL and NHL.Richter's syndrome (RS) is the transformation of CLL into an aggressive and rapidly fatal lymphoma, typically a diffuse large B cell lymphoma (DLBCL). RS is a challenging disease since very few effective treatment options exist for these patients and the available regimens, mainly based on R-CHOP scheme, show limited efficacy.We recently established patient-derived xenograft (PDX) models from RS patients and have shown that they can be used to test the efficacy of novel drugs and drug combinations 1,2. All available RS-PDX models were characterized by high-levels of CD37 expression, when assessed by RNA sequencing, reverse-transcriptase-polymerase chain reaction (RT-PCR), flow cytometry (FACS), western blot (WB) and immunohistochemistry (IHC). More precisely, two models (RS1316 and IP867/17) showed slightly higher CD37 levels compared to the others (RS9737 and RS1050).These models were used to test three different αCD37-ATACs®, ADCs which comprise amanitin-derivatives as payload. Amanitin (the main poison in the green deathcap mushroom) belongs to the well-known amatoxin family. Amanitin is taken up by OATP1B3 transporter, solely expressed on hepatocytes. Upon mushroom intoxication, it can lead to severe liver toxicity by inhibiting the RNA polymerase II. Upon conjugation to target-specific antibodies, the maximal tolerated dose is significantly increased by reducing the non-specific liver uptake. By binding to its antigen, ATACs deliver amanitin only into target-positive cancer cells while target negative cells show no off-target toxicity. Consistent with CD37 expression on the cell surface, ex-vivo treatment of freshly purified cells from RS-PDX tumor masses to αCD37-ATACs® resulted in increased apoptosis after 72 hours of treatment, with only minor differences among the 3 ATACs® and the models used. Since alpha-amanitin is a deadly toxin known to target human RNA polymerase II and, at high doses, also RNA polymerase III, we checked messenger RNA levels in basal conditions and after CD37-ATAC® treatment by looking at different housekeeping genes, and confirmed a reduction in global mRNA levels.αCD37-ATAC® efficacy was then assessed in vivo in systemic RS-PDX models where RS cells are intra-venously (i.v.) injected in the tail vein and cells distribute to different tissues (blood, spleen and bone marrow), resembling the human disease. Cells from RS1316, RS1050 and RS9737 models were injected into the tail vein and left to engraft 14 days, before mice were randomly assigned to vehicle or ATAC® groups. A single i.v. treatment for each αCD37-ATAC® was administered, testing two different doses for each compound, and mice were then monitored for survival. Overall, the single administration of all three ATACs® caused highly significant disease regression. In the RS1316 model, independently of the dose or tested ATAC®s, all treated mice, except one, were alive and disease-free until the end of the experiment, 140 days post cells injection, while survival of vehicle-treated mice was 65 days. FACS analysis to trace neoplastic cells in parenchymatous organs and bone marrow confirmed the absence of neoplastic cells. In the other 2 models, RS9737 and RS1050, even though ATAC® treatment did not result in complete disease eradication, a single administration of αCD37-ATAC® resulted in a dramatically increased survival (approximately 35-60 days, depending on the model and ATAC® used).Finally, CD37 expression was confirmed by RNA sequencing on a cohort of 15 primary RS samples, even though with variable levels. Compared to CLL cells, RS samples showed CD37 expression levels comparable to those reported for DLBCL cells.Overall, these data indicate CD37 as a potential target to treat RS patients with selective targeting αCD37-ATACs®.ATACs® is a registered trade mark of Heidelberg Pharma Research GmbH, Germany

Zanubrutinib in Combination with Venetoclax for Patients with Treatment-Naïve (TN) Chronic Lymphocytic Leukemia (CLL) or Small Lymphocytic Lymphoma (SLL) with del(17p): Early Results from Arm D of the SEQUOIA (BGB-3111-304) Trial

Zanubrutinib in Combination with Venetoclax for Patients with Treatment-Naïve (TN) Chronic Lymphocytic Leukemia (CLL) or Small Lymphocytic Lymphoma (SLL) with del(17p): Early Results from Arm D of the SEQUOIA (BGB-3111-304) Trial

Genomic Profiling In Fit, Elderly Patients Receiving Oral Fludarabine, Oral Cyclophosphamide and Intravenous Rituximab (ALLG CLL5 OFOCIR trial) As Initial Treatment Of Chronic Lymphocytic Leukemia (CLL)

BackgroundAnalysis for genomic alterations by fluorescence in-situ hybridization (FISH) allows prognostic stratification in chronic lymphocytic leukemia (CLL). Recurrent mutations in genes including NOTCH1, SF3B1, BIRC3 and others have recently been identified in patients with CLL by next-generation sequencing and may provide independent prognostic information (Rossi D et al. Blood 2013). The prognostic impact of these mutations following first-line therapy chemotherapy has not been consistent in the literature (Oscier D et al. Blood 2012; Ysebaert L et al. ASH Abstract 2012; Stilgenbauer S et al. ASH Abstracts 2012) and the prognostic significance of these mutations in elderly patients requiring therapy is not clearly defined (Chiaretti S et al. ASH Abstracts 2012). AimWe aimed to describe the incidence of genomic alterations by FISH and multiplexed targeted resequencing of genes with potential prognostic importance in an elderly population of patients requiring frontline treatment for CLL. MethodsPre-treatment peripheral blood and bone marrow aspirate samples were obtained from patients enrolled on a phase II randomized clinical trial investigating oral fludarabine, oral cyclophosphamide and i.v. rituximab (poFCivR) tolerance in previously untreated fit elderly patients with CLL (Australasian Leukemia and Lymphoma Group [ALLG] CLL5, ACTRN12608000404325). Peripheral blood lymphocytes were purified by Ficoll gradient separation. Bone marrow aspirate samples were analyzed for CLL-associated genomic changes with a Vysis CLL FISH probe kit (Abbott, Des Moines, IL). DNA was extracted from peripheral blood samples and we performed targeted genome sequencing of genes including TP53, ATM, NOTCH1, SF3B1, BIRC3, MYD88, XPO1 and FBXW7 using a TruSeq Custom Amplicon Design Panel on a MiSeq Sequencer as per manufacturer's protocol (Illumina, San Diego, CA). DNA mutation data was analyzed and compared to reported mutations in the literature and COSMIC database. Non-synonymous mutations with a mutation frequency >10% are reported. Results120 patients were enrolled into the CLL5 study and 78 samples were available for analysis. In these patients, FISH analysis identified 17p deletion in 10 pts (13%), 11q deletion in 6 pts (8%), trisomy 12 in 15 pts (19%), deletion 13q in 28 pts (36%), no abnormality (n=14, 18%), and not performed (n=5, 6%). By targeted sequencing, mutations were identified in TP53 (n=7, 9%), ATM (n=7, 9%), NOTCH1 (n=12, 15%), SF3B1 (n=10, 13%), MYD88 (n=6, 8%), BIRC3 (n=2, 3%), XPO1 (n=6, 8%), FBXW7 (n=4, 5%). Thirty patients (38%) did not have a mutation in one of these genes. Mutation distribution is demonstrated in Figure 1. Five of 7 mutations in TP53 occurred in the DNA-binding core domains (exons 5-8) and one mutation in the homo-oligomerization domain and one in exon 11. The majority of NOTCH1 mutations were identified in the PEST domains (11 of 12) and all but one mutation in SF3B1 were identified in the PP2A repeats 5-9. Correlation with patient characteristics, IGHV mutational sequencing and clinical outcome data is proceeding. [Display omitted] ConclusionWe demonstrate a high proportion of genomic mutations in fit patients age 65 years and older undergoing first-line therapy for CLL. By comparison with data from Italian CLL trials, UK LRF CLL4 and the CLL8 study, our study demonstrates similar mutational frequencies in previously described recurrently mutated genes. These mutations are assessable by massive parallel sequencing and may potentially offer useful predictive information in patients requiring therapy for CLL. AcknowledgmentsSupported by grants from CLL Global Research Foundation and Cancer Institute of NSW / Northern Translational Cancer Research Unit. Disclosures:Mulligan:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract 1062: Inhibition of ovarian and endometrial cancer cell proliferation by an anti-ROR1 monoclonal antibody

Abstract The non-canonical Wnt signalling receptor ROR1 has been shown to be aberrantly expressed in numerous cancers, including ovarian and endometrial cancer (EC). Cirmtuzumab is a humanised monoclonal antibody against ROR1 that blocks Wnt5a-induced ROR1 signalling. It has demonstrated safety and efficacy in several Phase I/II clinical trials for chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL) and Her2-negative breast cancer. The aim of this study was to investigate any anti-proliferative effect of cirmtuzumab in combination with commonly-used gynaecological cancer therapies (cisplatin, paclitaxel and the PARP inhibitor, olaparib) on high grade serous ovarian cancer (HGSOC) and EC cell lines including models of platinum resistance. The ROR1 positive HGSOC cells lines CaOV3, CaOV3CisR PEO1, PEO4 and EC cell lines Ishikawa, KLE were used in this study. First, IC50 for cisplatin, paclitaxel and olaparib in each cell line at 72h was determined using the cell counting kit 8 (CCK-8). Then, cells were seeded in 12-well plates and treated with cirmtuzumab at 25µg/ml or 50µg/ml for 4h prior to the addition of the chemotherapeutic agents at IC70 concentration. The effect of cirmtuzumab +/- agents was quantified using the IncuCyte S3 Live Cell Analysis System. Phase contrast cell images were obtained using a 10x objective lens within the instrument every 3h for 72h in total. The average confluence of each well was calculated and normalised against the baseline (time 0). Two-way ANOVA followed by Bonferroni post-test was performed to evaluate the effect of treatments. RNA and protein were extracted at the end of the incubation for qRTPCR and Western blot analysis. Single dose cirmtuzumab at both 25µg/ml and 50µg/ml significantly inhibited proliferation of CaOV3, CaOV3cisR, PEO1 and Ishikawa cells. 50µg/ml of cirmtuzumab decreased proliferation of KLE. Compared to paclitaxel alone, addition of 50µg/ml of cirmtuzumab significantly inhibited proliferation of CaOV3, CaOV3CisR, PEO1 and PEO4. Compared to cisplatin alone, addition of 25µg/ml of cirmtuzumab significantly inhibited proliferation of CaOV3CisR, PEO4; addition of 50µg/ml of cirmtuzumab significantly inhibited proliferation of CaOV3, CaOV3CisR, PEO4. Compared to olaparib alone, addition of 25µg/ml of cirmtuzumab significantly inhibited proliferation of CaOV3CisR; addition of 50µg/ml of cirmtuzumab significantly inhibited proliferation of CaOV3 and CaOV3CisR. No significant change in ROR1 or ROR2 expression levels was observed following cirmtuzumab treatment, however treatment did result in alterations to markers of epithelial-mesenchymal transition (EMT). Cirmtuzumab alone inhibited proliferation of ovarian cancer and EC cells in vitro, and could enhance the activity of commonly-used chemotherapeutic agents. This study supports the potential of cirmtuzumab or other ROR1 targeting therapies for treating women with HGSOC and EC. Citation Format: Dongli Liu, Gunnar F. Kaufmann, James B. Breitmeyer, Kristie-Ann Dickson, Deborah J. Marsh, Caroline E. Ford. Inhibition of ovarian and endometrial cancer cell proliferation by an anti-ROR1 monoclonal antibody [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 1062.