Citations

Abstract The management of chronic lymphocytic leukemia (CLL) has undergone unprecedented changes over the last decade. Modern targeted therapies are incorporated into clinical practice. Unfortunately, patients have begun to develop resistance or intolerance to multiple classes. Symptomatic patients previously treated with a BTK inhibitor (BTKi) and venetoclax represent a new and rapidly growing unmet need in CLL. Here, we define unmet needs in a modern treatment context. We also critically review the literature for PI3K inhibitors and chemoimmunotherapy and lack of data to support their utility following BTKis and venetoclax. Finally, we suggest opportunities to ensure the continued innovation for patients with CLL.

Abstract ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

The development of pancreatic cancer requires recruitment and activation of different macrophage populations. However, little is known about how macrophages are attracted to the pancreas after injury or an oncogenic event, and how they crosstalk with lesion cells or other cells of the lesion microenvironment. Here, we delineate the importance of CXCL10/CXCR3 signaling during the early phase of murine pancreatic cancer. We show that CXCL10 is produced by pancreatic precancerous lesion cells in response to IFNγ signaling and that inflammatory macrophages are recipients for this chemokine. CXCL10/CXCR3 signaling in macrophages mediates their chemoattraction to the pancreas, enhances their proliferation, and maintains their inflammatory identity. Blocking of CXCL10/CXCR3 signaling in vivo shifts macrophage populations to a tumor-promoting (Ym1 + , Fizz + , Arg1 + ) phenotype, increases fibrosis, and mediates progression of lesions, highlighting the importance of this pathway in PDA development. This is reversed when CXCL10 is overexpressed in PanIN cells.

TPS7570 Background: Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma (NHL), and although > 50% of pts achieve long-term remission with first-line therapy, pts with R/R disease as well as those with R/R grade 3b follicular lymphoma (FL), double-, or triple-hit high-grade lymphomas have poor long-term outcomes (Crump 2017; Kahl 2016; Jain 2012). Autologous (auto) chimeric antigen receptor (CAR) T cell therapy has provided additional options for pts with R/R disease, but only when leukapheresis and manufacturing prove feasible (Jacobson 2020). Allogeneic (allo) CAR-T cells were designed specifically to address these unmet needs by using healthy donor T cells to produce a readily available product and remove the need for bridging chemotherapy. We are currently investigating the safety and efficacy of CTX110, an allo anti-CD19 CAR-T cell product modified by using CRISPR/Cas9-editing to disrupt the endogenous T-cell receptor (TCR) alpha constant (TRAC) locus in order to remove TCR expression and disrupt β2-microglobulin, which eliminates major histocompatibility complex (MHC) class I expression. Disruption of the TCR should significantly reduce or eliminate risks of graft-versus-host disease and elimination of MHC class I expression may increase CAR-T cell persistence by mitigating CTX110 rejection. In addition, the anti-CD19 CAR transgene construct is precisely inserted into the TRAC locus. Methods: The Phase 1 CARBON trial (NCT04035434) is an open-label, multicenter, global study evaluating the safety and efficacy of CTX110 in pts ≥18 y with R/R DLBCL NOS, double- or triple-hit DLBCL, or transformed or grade 3b FL with ≥2 prior lines of therapy or who are ineligible for/refused prior auto hematopoietic stem cell transplant (HSCT). Pts who received prior auto CAR-T or allo HSCT are excluded. Pts will receive lymphodepleting chemotherapy with fludarabine 30mg/m2 and cyclophosphamide 500mg/m2 for 3 days, followed by CTX110 infusion. In part A, dose escalation will be performed using a 3+3 design. Upon completion of dose finding, the cohort will be expanded to further assess safety signals and efficacy including the primary efficacy endpoint of overall response rate. Key secondary efficacy endpoints include duration of response, progression-free survival, and overall survival. The trial is currently open and enrolling. Clinical trial information: NCT04035434.

7502 Background: The BCL-2i venetoclax is active in certain HMs but can increase the risk of tumor lysis syndrome (TLS), requiring a 5-week dose ramp-up for CLL patients. Cases of severe neutropenia with venetoclax treatment have also been reported. Lisaftoclax is a novel, potent, selective BCL-2i that is active against HMs and is under clinical development. Methods: This first-in-human global phase I dose study assessed the safety, PK, PD, efficacy, and MTD/RP2D of lisaftoclax in patients with R/R CLL and other HMs. Lisaftoclax was orally administered daily in a 28-day cycle. Patients with CLL or intermediate-high TLS risk were initiated on a daily ramp-up schedule until the assigned dose before the study cycles. Results: On January 7, 2021, 35 pts had been enrolled and treated with lisaftoclax at doses ranging from 20 to 1,200 mg, with a median (range) of 2 (1-13) prior lines of treatment, and had diagnoses of R/R CLL or SLL (n = 15), MM (n = 6), FL (n = 5), WM (n = 4), and either AML, MCL, DLBCL, MDS, or HCL (n = 1 each). No DLT has been observed, even though 1,200 mg was considered as the highest dose treated. The MTD has not been reached, and no laboratory or clinical TLS has been reported. Any grade TRAEs in > 10% of pts included neutropenia (22.9%) and anemia (17.1%; hematologic), and fatigue (28.6%), diarrhea (17.1%), and nausea (11.4%; nonhematologic). Grade >3 TRAEs were neutropenia (14.3%) and thrombocytopenia, leukopenia, lymphopenia, fatigue, and nausea (2.9% of pts each). In CLL/SLL pts, grade 3-4 TRAEs included neutropenia (13.3%) and thrombocytopenia (6.7%), which did not cause treatment-related discontinuation. In all, 12 of 35 pts (34.3%) had non-treatment-related SAEs, and only two pts experienced > 1 SAE. With a median (range) treatment of 7 (3-20) cycles, 12 of 14 evaluable R/R CLL/SLL pts achieved PR, for an ORR of 85.7% and a median (range) time to response of 3 (2-7) cycles. Absolute lymphocyte counts (ALCs) were reduced at lisaftoclax doses as low as 20 mg/day. The preliminary PK profile showed that exposures increased with lisaftoclax doses from 20 to 1,200 mg (average half-life: 4-5 hours). On BH3 profiling, lisaftoclax rapidly triggered changes in BCL-2 complex in CLL/SLL pt samples, which were consistent with rapid clinical reductions in ALCs. Conclusions: Lisaftoclax was well tolerated up to 1,200 mg/day. No TLS was observed, even with the daily ramp-up schedule. There were no significant new or unmanageable safety findings, and the ORR in R/R CLL/SLL pts was 85.7%. Grade 3-4 TRAEs were infrequent, even at dose levels of 800 mg and above. BCL-2i lisaftoclax offers a treatment alternative for patients with R/R CLL/SLL and other HMs, with a daily ramp-up schedule that may be more pt “user friendly” and a favorable preliminary safety profile. Internal study identifier APG2575-001. Clinical trial information: NCT03537482.

TPS6093 Background: Since patients with early-stage oral cavity cancer (OCC; T1-2N0M0; AJCC 8th ed) have a 20-30% rate of occult nodal metastases despite clinical and radiographic assessment, standard of care treatment includes elective neck dissection (END). Many patients have comprehensive surgical management of the regional cervical nodal basin even though the majority of those necks (70-80%) will not contain disease. Assessment of draining first echelon lymph nodes by sentinel lymph node (SLN) biopsy (Bx), a less invasive surgical procedure, may provide an alternative to END, while potentially reducing morbidity and cost. A decisive clinical trial comparing SLN Bx versus END can focus the HNC clinical and research community and resources on establishing the standard of care for management of the neck in early-stage OCC. Methods: In order to address the efficacy of SLN Bx in this population, we recently activated an international multi-institutional phase II/III prospective trial randomizing patients to two surgical arms: SLN Bx and END. PET/CT is an integral imaging biomarker in this trial. A node-negative PET/CT study with central read is required before randomization. Patients with a positive PET/CT central result will remain in a registry to compare imaging findings with final neck pathology. Given the current evidence available regarding morbidity for SLN Bx versus END, the phase II will determine if patient-reported neck and shoulder function and related QOL at 6 months after surgery using the Neck Dissection Impairment Index (NDII) shows a signal of superiority of SLN Bx compared to END. A total of 228 randomized patients with negative PET/CT for potential evaluation of shoulder-related morbidity with difference in 6-month NDII scores (minimum important difference ³7.5; one-sided a = 0.10; 90% power) will serve as the “Go/No-Go” decision to move forward into phase III. The phase III portion is a non-inferiority (NI) trial with disease-free survival (DFS) as the primary endpoint (NI margin hazard ratio 1.34 based on a 5% absolute difference in 2-year DFS; one-sided alpha 0.05; 80% power, and an interim look for efficacy at 67% of the events based on an O’Brien-Fleming boundary). The NDII at 6 months after surgery is a hierarchical co-primary endpoint for the phase III. Target accrual of phase III is 618 PET/CT negative patients, including those randomized in phase II (297 DFS events required for the final analysis). In addition to radiotherapy and imaging credentialing, quality assurance will include central pathology review of all negative SLN Bx cases and surgeon credentialing through an education course and SLN Bx and END case review by the surgical co-chairs. A surgical quality assurance working group will review all trial SLN Bx and END outcomes. As of 02/15/21, 7 patients have been screened and 6 of the planned 228 randomized patients in phase II have been enrolled. Clinical trial information: NCT04333537.

Abstract BACKGROUND Clinicoradiologic differentiation between benign and malignant peripheral nerve sheath tumors (PNSTs) has important management implications. OBJECTIVE To develop and evaluate machine-learning approaches to differentiate benign from malignant PNSTs. METHODS We identified PNSTs treated at 3 institutions and extracted high-dimensional radiomics features from gadolinium-enhanced, T1-weighted magnetic resonance imaging (MRI) sequences. Training and test sets were selected randomly in a 70:30 ratio. A total of 900 image features were automatically extracted using the PyRadiomics package from Quantitative Imaging Feature Pipeline. Clinical data including age, sex, neurogenetic syndrome presence, spontaneous pain, and motor deficit were also incorporated. Features were selected using sparse regression analysis and retained features were further refined by gradient boost modeling to optimize the area under the curve (AUC) for diagnosis. We evaluated the performance of radiomics-based classifiers with and without clinical features and compared performance against human readers. RESULTS A total of 95 malignant and 171 benign PNSTs were included. The final classifier model included 21 imaging and clinical features. Sensitivity, specificity, and AUC of 0.676, 0.882, and 0.845, respectively, were achieved on the test set. Using imaging and clinical features, human experts collectively achieved sensitivity, specificity, and AUC of 0.786, 0.431, and 0.624, respectively. The AUC of the classifier was statistically better than expert humans ( P = .002). Expert humans were not statistically better than the no-information rate, whereas the classifier was ( P = .001). CONCLUSION Radiomics-based machine learning using routine MRI sequences and clinical features can aid in evaluation of PNSTs. Further improvement may be achieved by incorporating additional imaging sequences and clinical variables into future models.