Vepafestinib is a pharmacologically advanced RET-selective inhibitor with high CNS penetration and inhibitory activity against RET solvent front mutations.

RET receptor tyrosine kinase is activated in various cancers (lung, thyroid, colon and pancreatic, among others) through oncogenic fusions or gain-of-function single-nucleotide variants. Small-molecule RET kinase inhibitors became standard-of-care therapy for advanced malignancies driven by RET. The therapeutic benefit of RET inhibitors is limited, however, by acquired mutations in the drug target as well as brain metastasis, presumably due to inadequate brain penetration. Here, we perform preclinical characterization of vepafestinib (TAS0953/HM06), a next-generation RET inhibitor with a unique binding mode. We demonstrate that vepafestinib has best-in-class selectivity against RET, while exerting activity against commonly reported on-target resistance mutations (variants in RETL730, RETV804 and RETG810), and shows superior pharmacokinetic properties in the brain when compared to currently approved RET drugs. We further show that these properties translate into improved tumor control in an intracranial model of RET-driven cancer. Our results underscore the clinical potential of vepafestinib in treating RET-driven cancers.

Clinical Outcomes With Pembrolizumab-Based Therapies in Recurrent/Refractory NSCLC After Chemoradiation and Consolidative Durvalumab.

BACKGROUND: Often, patients with NSCLC experience recurrent/refractory (R/R) disease within 2 years of chemoradiation (CRT) and consolidative durvalumab. Despite prior immune checkpoint inhibitor exposure, immunotherapy with or without chemotherapy is typically initiated if a driver-oncogene is absent. However, there remains a paucity of data regarding the efficacy of immunotherapy in this patient population. Here, we present survival outcomes associated with pembrolizumab for R/R NSCLC. MATERIALS AND METHODS: We retrospectively assessed adults with NSCLC who received pembrolizumab for R/R disease between January 2016 to January 2023. Primary objective was to estimate OS and PFS in this cohort compared to historical outcomes. Secondary objective was to compare OS and PFS among subgroups. RESULTS: Fifty patients were evaluated. Median follow-up time was 11.3 months (2.9-38.2). OS was 10.6 months (95% CI, 8.8-19.2); 1-year OS rate 49% (95% CI, 36 - 67%). PFS was 6.1 months (95% CI, 4.7-9.0); 1-year PFS rate 25% (95% CI, 15%-42%). Current smokers had significantly better median OS/PFS as compared to former smokers (NA vs. 10.5 and 9.9 vs. 6.0 months, respectively). The addition of chemotherapy demonstrated an OS benefit (median OS 12.9 vs. 6.0 months) but was not statistically significant. CONCLUSION: Patients with R/R NSCLC represent a distinct cohort with inferior survival outcomes when compared to those with de novo stage IV disease treated with pembrolizumab-based regimens. Based on our findings, we recommend oncologists exercise caution when considering checkpoint inhibitor monotherapy in the front-line setting for R/R NSCLC, regardless of PD-L1 expression.

Comutations and KRASG12C Inhibitor Efficacy in Advanced NSCLC.

Molecular modifiers of KRASG12C inhibitor (KRASG12Ci) efficacy in advanced KRASG12C-mutant NSCLC are poorly defined. In a large unbiased clinicogenomic analysis of 424 patients with non-small cell lung cancer (NSCLC), we identified and validated coalterations in KEAP1, SMARCA4, and CDKN2A as major independent determinants of inferior clinical outcomes with KRASG12Ci monotherapy. Collectively, comutations in these three tumor suppressor genes segregated patients into distinct prognostic subgroups and captured ∼50% of those with early disease progression (progression-free survival ≤3 months) with KRASG12Ci. Pathway-level integration of less prevalent coalterations in functionally related genes nominated PI3K/AKT/MTOR pathway and additional baseline RAS gene alterations, including amplifications, as candidate drivers of inferior outcomes with KRASG12Ci, and revealed a possible association between defective DNA damage response/repair and improved KRASG12Ci efficacy. Our findings propose a framework for patient stratification and clinical outcome prediction in KRASG12C-mutant NSCLC that can inform rational selection and appropriate tailoring of emerging combination therapies. SIGNIFICANCE: In this work, we identify co-occurring genomic alterations in KEAP1, SMARCA4, and CDKN2A as independent determinants of poor clinical outcomes with KRASG12Ci monotherapy in advanced NSCLC, and we propose a framework for patient stratification and treatment personalization based on the comutational status of individual tumors. See related commentary by Heng et al., p. 1513. This article is highlighted in the In This Issue feature, p. 1501.

Novel patient-derived models of desmoplastic small round cell tumor confirm a targetable dependency on ERBB signaling.

Desmoplastic small round cell tumor (DSRCT) is characterized by the t(11;22)(p13;q12) translocation, which fuses the transcriptional regulatory domain of EWSR1 with the DNA-binding domain of WT1, resulting in the oncogenic EWSR1-WT1 fusion protein. The paucity of DSRCT disease models has hampered preclinical therapeutic studies on this aggressive cancer. Here, we developed preclinical disease models and mined DSRCT expression profiles to identify genetic vulnerabilities that could be leveraged for new therapies. We describe four DSRCT cell lines and one patient-derived xenograft model. Transcriptomic, proteomic and biochemical profiling showed evidence of activation of the ERBB pathway. Ectopic expression of EWSR1-WT1 resulted in upregulation of ERRB family ligands. Treatment of DSRCT cell lines with ERBB ligands resulted in activation of EGFR, ERBB2, ERK1/2 and AKT, and stimulation of cell growth. Antagonizing EGFR function with shRNAs, small-molecule inhibitors (afatinib, neratinib) or an anti-EGFR antibody (cetuximab) inhibited proliferation of DSRCT cells. Finally, treatment of mice bearing DSRCT xenografts with a combination of cetuximab and afatinib significantly reduced tumor growth. These data provide a rationale for evaluating EGFR antagonists in patients with DSRCT. This article has an associated First Person interview with the joint first authors of the paper.

Primary central nervous system diffuse large B-cell lymphoma masqueraded as Bing-Neel syndrome: Steps in management and review of future directions.

Bing-Neel syndrome (BNS) remains a rare complication of Waldenstrom Macroglobulinemia. Given the paucity of this disease, treatment guidelines are based on small clinical trials with limited participants. Here, we present a case of primary CNS diffuse large B-cell lymphoma masqueraded as BNS that developed while on ibrutinib therapy.

Membrane-based therapeutic plasma exchange: Hemodynamics and operational characteristics leading to procedure failure.

BACKGROUND AND OBJECTIVES: Therapeutic plasma exchange (TPE) is a blood purification treatment capable of removing large molecular weight substances from plasma. It is commonly used for the removal of circulating pathogenic immunoglobulins presumed to be the cause of many autoimmune diseases. TPE can be performed with a membrane-based system (mTPE) or a centrifugal-based system (cTPE). When plasma separation is performed with a membrane, filter clotting can lead to longer treatment time, higher cost and can negatively impact patient satisfaction. In this study, we examine the operational characteristics that might influence filter life. DESIGN, SETTING, PARTICIPANTS, & MEASURES: We report on 24 patients, with a total of 135 mTPE treatments in a single tertiary care academic center using the NxStage machine. The study focuses on treatment specific parameters that may lead to procedure failure. The main parameters of interest were transmembrane pressure (TMP) and the filtration fraction as displayed on the machine (FFd) compared to the calculated filtration fraction (FFc). Primary outcome was to measure whether TMP, FFc, and FFd influenced filter survival. Secondary outcomes included factors that might have indirectly resulted in filter failure, including hematocrit (Hct), platelet count, heparin use, and intra-treatment calcium administration. RESULTS: In this study, we demonstrated that machine displayed filtration fractions (FFd) were lower than FFc and this difference was significantly larger in TPE sessions that experienced a clotting event (7.58 vs 6.22, P = .031). TPE sessions that clotted had a higher mean TMP (57.48 mmHg vs 44.43 mmHg, P = .001) and clotting events tended to have a lower mean blood flow rate (175.83 mL/min vs 189.55 mL/min, P = .002). In TPE sessions that received prefilter calcium administration, a higher mean dose of calcium gluconate was found in the sessions that experienced clotting (3.27 g vs 2.70 g, P = .013). Patients who experienced at least one clotting event were noted to be heavier than those patients without any clotting events (91.52 kg vs 72.15 kg, P = .040). Prefilter heparin administration was not associated with a lower incidence of filter clotting. We did not find a statistically significant difference in clotting events based upon type of intravenous access, pretreatment hematocrit, or pretreatment platelet counts. CONCLUSION: Among patients undergoing mTPE, machine FFd on the NxStage system are consistently lower than FFc. Treatments where there was a greater difference between displayed and FFc had a greater likelihood of filter clotting. Treatments with higher TMP were associated with failed treatments. Prefilter calcium administration during treatment was associated with increased filter clotting. Lower blood flow rates and higher patient weight were also associated with increased filter clotting. Prefilter heparin administration did not reduce the incidence of filter clotting.

Novel Preclinical Patient-Derived Lung Cancer Models Reveal Inhibition of HER3 and MTOR Signaling as Therapeutic Strategies for NRG1 Fusion-Positive Cancers.

INTRODUCTION: NRG1 rearrangements produce chimeric ligands that subvert the ERBB pathway to drive tumorigenesis. A better understanding of the signaling networks that mediate transformation by NRG1 fusions is needed to inform effective therapeutic strategies. Unfortunately, this has been hampered by a paucity of patient-derived disease models that faithfully recapitulate this molecularly defined cancer subset. METHODS: Patient-derived xenograft (PDX) and cell line models were established from NRG1-rearranged lung adenocarcinoma samples. Transcriptomic, proteomic, and biochemical analyses were performed to identify activated pathways. Efficacy studies were conducted to evaluate HER3- and MTOR-directed therapies. RESULTS: We established a pair of PDX and cell line models of invasive mucinous lung adenocarcinoma (LUAD) (LUAD-0061AS3, SLC3A2-NRG1), representing the first reported paired in vitro and in vivo model of NRG1-driven tumors. Growth of LUAD-0061AS3 models was reduced by the anti-HER3 antibody GSK2849330. Transcriptomic profiling revealed activation of the MTOR pathway in lung tumor samples with NRG1 fusions. Phosphorylation of several MTOR effectors (S6 and 4EBP1) was higher in LUAD-0061AS3 cells compared with human bronchial epithelial cells and the breast cancer cell line MDA-MB-175-VII (DOC4-NRG1 fusion). Accordingly, LUAD-0061AS3 cells were more sensitive to MTOR inhibitors than MDA-MB-175-VII cells and targeting the MTOR pathway with rapamycin blocked growth of LUAD-0061AS3 PDX tumors in vivo. In contrast, MDA-MB-175-VII breast cancer cells had higher MAPK pathway activation and were more sensitive to MEK inhibition. CONCLUSIONS: We identify the MTOR pathway as a candidate vulnerability in NRG1 fusion-positive lung adenocarcinoma that may warrant further preclinical evaluation, with the eventual goal of finding additional therapeutic options for patients in whom ERBB-directed therapy fails. Moreover, our results uncover heterogeneity in downstream oncogenic signaling among NRG1-rearranged cancers, possibly tumor type-dependent, the therapeutic significance of which requires additional investigation.

The Anti-HER3 mAb Seribantumab Effectively Inhibits Growth of Patient-Derived and Isogenic Cell Line and Xenograft Models with Oncogenic NRG1 Fusions.

PURPOSE: Oncogenic fusions involving the neuregulin 1 (NRG1) gene are found in approximately 0.2% of cancers of diverse histologies. The resulting chimeric NRG1 proteins bind predominantly to HER3, leading to HER3-HER2 dimerization and activation of downstream growth and survival pathways. HER3 is, therefore, a rational target for therapy in NRG1 fusion-driven cancers. EXPERIMENTAL DESIGN: We developed novel patient-derived and isogenic models of NRG1-rearranged cancers and examined the effect of the anti-HER3 antibody, seribantumab, on growth and activation of signaling networks in vitro and in vivo. RESULTS: Seribantumab inhibited NRG1-stimulated growth of MCF-7 cells and growth of patient-derived breast (MDA-MB-175-VII, DOC4-NRG1 fusion) and lung (LUAD-0061AS3, SLC3A2-NRG1 fusion) cancer cells harboring NRG1 fusions or NRG1 amplification (HCC-95). In addition, seribantumab inhibited growth of isogenic HBEC cells expressing a CD74-NRG1 fusion (HBECp53-CD74-NRG1) and induced apoptosis in MDA-MB-175-VII and LUAD-0061AS3 cells. Induction of proapoptotic proteins and reduced expression of the cell-cycle regulator, cyclin D1, were observed in seribantumab-treated cells. Treatment of MDA-MB-175-VII, LUAD-0061AS3, and HBECp53-CD74-NRG1 cells with seribantumab reduced phosphorylation of EGFR, HER2, HER3, HER4, and known downstream signaling molecules, such as AKT and ERK1/2. Significantly, administration of seribantumab to mice bearing LUAD-0061AS3 patient-derived xenograft (PDX) and OV-10-0050 (ovarian cancer with CLU-NRG1 fusion) PDX tumors induced regression of tumors by 50%-100%. Afatinib was much less effective at blocking tumor growth. CONCLUSIONS: Seribantumab treatment blocked activation of the four ERBB family members and of downstream signaling, leading to inhibition of NRG1 fusion-dependent tumorigenesis in vitro and in vivo in breast, lung, and ovarian patient-derived cancer models.

MET Exon 14-altered Lung Cancers and MET Inhibitor Resistance.

PURPOSE: MET tyrosine kinase inhibitors (TKIs) can achieve modest clinical outcomes in MET exon 14-altered lung cancers, likely secondary to primary resistance. Mechanisms of primary resistance remain poorly characterized and comprehensive proteomic analyses have not previously been performed. EXPERIMENTAL DESIGN: We performed hybrid capture-based DNA sequencing, targeted RNA sequencing, cell-free DNA sequencing, selected reaction monitoring mass spectrometry (SRM-MS), and immunohistochemistry on patient samples of MET exon 14-altered lung cancers treated with a MET TKI. Associations between overall response rate (ORR), progression-free survival (PFS), and putative genomic alterations and MET protein expression were evaluated. RESULTS: Seventy-five of 168 MET exon 14-altered lung cancers received a MET TKI. Previously undescribed (zygosity, clonality, whole-genome duplication) and known (copy-number focality, tumor mutational burden, mutation region/type) genomic factors were not associated with ORR/PFS (P > 0.05). In contrast, MET expression was associated with MET TKI benefit. Only cases with detectable MET expression by SRM-MS (N = 15) or immunochemistry (N = 22) responded to MET TKI therapy, and cancers with H-score ≥ 200 had a higher PFS than cancers below this cutoff (10.4 vs. 5.5 months, respectively; HR, 3.87; P = 0.02). CONCLUSIONS: In MET exon 14-altered cancers treated with a MET TKI, a comprehensive analysis of previously unknown and known genomic factors did not identify a genomic mechanism of primary resistance. Instead, MET expression correlated with benefit, suggesting the potential role of interrogating the proteome in addition to the genome in confirmatory prospective trials.

New onset diabetes with ketoacidosis following nivolumab immunotherapy: A case report and review of literature.

INTRODUCTION: Immune-checkpoint inhibitors have become an increasingly popular form of systemic therapy for cancer treatment. Their use has proven to be so effective that certain regimens have gained approval as first-line therapy for various solid tumor types. The most common and well-studied forms of immunotherapy include agents that target cytotoxic T-lymphocyte antigen-4, programmed death-1, and programmed death ligand-1. These therapies act by blocking signaling between immune cells and cancer cells which subsequently augment T cell-mediated destruction of tumor cells. CASE REPORT: Here, we report a case of a 77-year-old black male with no history of or risk factors for diabetes mellitus who presented with acute onset of diabetic ketoacidosis after beginning immunotherapy with nivolumab for metastatic high-grade neuroendocrine tumor of the lung. He was admitted and treated for diabetic ketoacidosis but required prolonged use of an insulin infusion with frequent need of intravenous dextrose due to labile blood sugars. The patient was eventually discharged and discontinued further immunotherapy with nivolumab. DISCUSSION: Due to the unique mechanisms by which immune-checkpoint inhibitors cause immune-mediated destruction of tumor cells, clinicians may be challenged with their associated autoimmune complications referred to as immune-related adverse events. In particular, the incidence of endocrine dysfunction following immune-checkpoint inhibitor therapy is approximately 12%, with the development of insulin-dependent diabetes mellitus being a rare complication. Increasing awareness of immune-related adverse events is essential for the early recognition and effective management of patients who present with life-threatening complications related to immune-checkpoint inhibitor therapy.

RET inhibition in novel patient-derived models of RET-fusion positive lung adenocarcinoma reveals a role for MYC upregulation.

Multi-kinase RET inhibitors, such as cabozantinib and RXDX-105, are active in lung cancer patients with RET fusions; however, the overall response rates to these two drugs are unsatisfactory compared to other targeted therapy paradigms. Moreover, these inhibitors may have different efficacies against RET rearrangements depending on the upstream fusion partner. A comprehensive preclinical analysis of the efficacy of RET inhibitors is lacking due to a paucity of disease models harboring RET rearrangements. Here we generated two new patient-derived xenograft (PDX) models, one new patient-derived cell line, one PDX-derived cell line, and several isogenic cell lines with RET fusions. Using these models, we re-examined the efficacy and mechanism of action of cabozantinib and found that this RET inhibitor was effective at blocking growth of cell lines, activating caspase 3/7 and inhibiting activation of ERK and AKT. Cabozantinib treatment of mice bearing RET-fusion-positive cell line xenografts and two PDXs significantly reduced tumor proliferation without adverse toxicity. Moreover, cabozantinib was effective at reducing growth of a lung cancer PDX that was not responsive to RXDX-105. Transcriptomic analysis of lung tumors and cell lines with RET alterations showed activation of a MYC signature and this was suppressed by treatment of cell lines with cabozantinib. MYC protein levels were rapidly depleted following cabozantinib treatment. Taken together, our results demonstrate that cabozantinib is an effective agent in preclinical models harboring RET rearrangements with three different 5' fusion partners (CCDC6, KIF5B and TRIM33). Notably, we identify MYC as a protein that is upregulated by RET expression and down-regulated by cabozantinib treatment, opening up potentially new therapeutic avenues for combinatorial targeting RET-fusion driven lung cancers. The novel RET fusion-dependent preclinical models described herein represent valuable tools for further refinement of current therapies and the evaluation of novel therapeutic strategies.

Primary Bone Lymphoma: A Case Series and Review of Literature.

Primary bone lymphoma (PBL) is a subtype of lymphoma that exclusively affects skeletal tissue. Despite the relatively common involvement of skeletal structures as a manifestation of non-Hodgkin's lymphoma (NHL), primary and exclusive involvement of the skeletal system is rare. The prevalence of PBL is estimated to be 3-7% amongst primary bone tumors and less than 2% amongst all lymphomas in adults. However, the definition of primary bone lymphoma has been inconsistent over time. Within our institution, we identified four cases of primary bone lymphoma based on diagnostic criteria formed from the general consensus of multiple organizations, including the World Health Organization (WHO) and International Extranodal Lymphoma Study Group (IELSG). Here, we discuss the distinct characteristics amongst these cases in addition to performing a systematic review of current literature regarding this lymphoproliferative entity.

Primary central nervous system marginal zone B-cell lymphoma arising from the dural meninges: A case report and review of literature.

Primary central nervous system (CNS) marginal zone B-cell lymphoma (MZBCL) arising from the dural meninges is a rare but indolent disease. This malignancy can present in various ways, hence making it difficult to diagnose. Biopsy results dictate an appropriate treatment plan, which commonly consists of a combination of surgical resection, whole brain radiotherapy and systemic therapy.

A Case of Immunotherapy-Induced Colitis Complicated by Perforation and Treated with Infliximab Postoperatively.

The advent of checkpoint inhibitor therapy in medical oncology has led to an increase in hospitalizations for immune-related adverse effects. Severe colitis has been reported in approximately 5% of patients treated with cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) inhibitors, such as ipilimumab. Standard management for those with severe colitis includes administration of systemic corticosteroids with the reservation of antitumor necrosis factor (anti-TNF) therapy, such as infliximab, if there has been no improvement. Rarely, immunotherapy-induced colitis can become life-threatening and result in bowel perforation requiring surgical intervention. Yet, there are no specific recommendations for medical management following colectomy in these situations. In cases of severe colitis from Crohn's disease, postoperative treatment with infliximab has been found to be safe when administered shortly after intestinal resection. However, there remains limited data to support administration of infliximab following bowel perforation due to immunotherapy-induced colitis. Our case illustrates management of a severe adverse reaction to checkpoint inhibitor therapy and the need to further evaluate the role of infliximab postoperatively in patients who develop colitis complicated by bowel perforation.

Response to ERBB3-Directed Targeted Therapy in NRG1-Rearranged Cancers.

NRG1 rearrangements are oncogenic drivers that are enriched in invasive mucinous adenocarcinomas (IMA) of the lung. The oncoprotein binds ERBB3-ERBB2 heterodimers and activates downstream signaling, supporting a therapeutic paradigm of ERBB3/ERBB2 inhibition. As proof of concept, a durable response was achieved with anti-ERBB3 mAb therapy (GSK2849330) in an exceptional responder with an NRG1-rearranged IMA on a phase I trial (NCT01966445). In contrast, response was not achieved with anti-ERBB2 therapy (afatinib) in four patients with NRG1-rearranged IMA (including the index patient post-GSK2849330). Although in vitro data supported the use of either ERBB3 or ERBB2 inhibition, these clinical results were consistent with more profound antitumor activity and downstream signaling inhibition with anti-ERBB3 versus anti-ERBB2 therapy in an NRG1-rearranged patient-derived xenograft model. Analysis of 8,984 and 17,485 tumors in The Cancer Genome Atlas and MSK-IMPACT datasets, respectively, identified NRG1 rearrangements with novel fusion partners in multiple histologies, including breast, head and neck, renal, lung, ovarian, pancreatic, prostate, and uterine cancers.Significance: This series highlights the utility of ERBB3 inhibition as a novel treatment paradigm for NRG1-rearranged cancers. In addition, it provides preliminary evidence that ERBB3 inhibition may be more optimal than ERBB2 inhibition. The identification of NRG1 rearrangements across various solid tumors supports a basket trial approach to drug development. Cancer Discov; 8(6); 686-95. ©2018 AACR.See related commentary by Wilson and Politi, p. 676This article is highlighted in the In This Issue feature, p. 663.