Digital droplet PCR analysis of organoids generated from mouse mammary tumors demonstrates proof-of-concept capture of tumor heterogeneity.

Breast cancer metastases exhibit many different genetic alterations, including copy number amplifications (CNA). CNA are genetic alterations that are increasingly becoming relevant to breast oncology clinical practice. Here we identify CNA in metastatic breast tumor samples using publicly available datasets and characterize their expression and function using a metastatic mouse model of breast cancer. Our findings demonstrate that our organoid generation can be implemented to study clinically relevant features that reflect the genetic heterogeneity of individual tumors.

Targeting Acute Myeloid Leukemia Stem Cells Through Perturbation of Mitochondrial Calcium.

Acute myeloid leukemia stem cells (LSCs) are uniquely reliant on oxidative phosphorylation (OXPHOS) for survival. Moreover, maintenance of OXPHOS is dependent on BCL-2, creating a therapeutic opportunity to target LSCs using the BCL-2 inhibitor venetoclax. While venetoclax-based regimens have shown promising clinical activity, the emergence of drug resistance is prevalent. Thus, in the present study, we investigated how mitochondrial properties may influence venetoclax responsiveness. Our data show that utilization of mitochondrial calcium is fundamentally different between drug-responsive and non-responsive LSCs. By comparison, venetoclax-resistant LSCs demonstrate a more active metabolic (i.e. OXPHOS) status with relatively high levels of calcium. Consequently, we tested genetic and pharmacological approaches to target the mitochondrial calcium uniporter, MCU. We demonstrate that inhibition of calcium uptake reduces OXPHOS and leads to eradication of venetoclax-resistant LSCs. These findings demonstrate a central role for calcium signaling in LSCs and provide an avenue for clinical management of venetoclax resistance.

A systematic review and meta-analysis of pathologic complete response rates for patients with cholangiocarcinoma treated on liver transplant protocols.

BACKGROUND AND OBJECTIVES: Many heterogenous orthotopic liver transplant (OLT) protocols exist for patients with unresectable cholangiocarcinoma. Little is known about the incidence, predictors for, and the significance of achieving a pathologic complete response (pCR). METHODS: We performed a systematic review through September 2022 of the PubMed, Embase, and Web of Science databases. A random-effect meta-analysis was conducted to pool data across studies with reported pCR rates. Heterogeneity between treatment protocols was assessed via subgroup analysis. The pCR and 1-, 3-, and 5-year recurrence-free survival (RFS) and overall survival (OS) rates were extracted as outcomes of interest. RESULTS: A total of 15 studies reported pCR rates and were grouped by use of the Mayo protocol (4/15), stereotactic body radiation therapy (2/15), and an Other category (9/15). The pooled pCR rate among all studies was 32%. Both radiation technique and duration of CHT showed no significant association with pCR (p = 0.05 and 0.13, respectively). Pooled 1-year RFS and OS after any neoadjuvant therapy and OLT was 80% (95% confidence interval [CI], 0.61-0.91), and 91% (95% CI, 0.87-0.94), respectively. There was no 1-year OS difference detected among the three groups. pCR was not associated with OS in the meta-regression. Pooled 3- and 5-year OS among all studies was 72% and 61%, respectively. CONCLUSIONS: The pooled incidence of pCR was 32%. Differences in radiation technique did not appear to influence pCR rates and upon meta-regression, pCR was not a surrogate marker for survival.

Antibody targeting of conserved sites of vulnerability on the SARS-CoV-2 spike receptor-binding domain.

Given the continuous emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VoCs), immunotherapeutics that target conserved epitopes on the spike (S) glycoprotein have therapeutic advantages. Here, we report the crystal structure of the SARS-CoV-2 S receptor-binding domain (RBD) at 1.95 Å and describe flexibility and distinct conformations of the angiotensin-converting enzyme 2 (ACE2)-binding site. We identify a set of SARS-CoV-2-reactive monoclonal antibodies (mAbs) with broad RBD cross-reactivity including SARS-CoV-2 Omicron subvariants, SARS-CoV-1, and other sarbecoviruses and determine the crystal structures of mAb-RBD complexes with Ab246 and CR3022 mAbs targeting the class IV site, WRAIR-2134, which binds the recently designated class V epitope, and WRAIR-2123, the class I ACE2-binding site. The broad reactivity of class IV and V mAbs to conserved regions of SARS-CoV-2 VoCs and other sarbecovirus provides a framework for long-term immunotherapeutic development strategies.

Valve-in-Valve Transcatheter Aortic Valve Replacement During Second Trimester of Pregnancy.

Critical bioprosthetic aortic valve stenosis is a rare finding in the second trimester of pregnancy. We present the case of a successful valve-in-valve transcatheter aortic valve replacement in a 16-weeks-pregnant patient. We describe the significant role of the multidisciplinary heart team during preconception and pregnancy.

Targeting Acute Myeloid Leukemia Stem Cells Through Perturbation of Mitochondrial Calcium.

We previously reported that acute myeloid leukemia stem cells (LSCs) are uniquely reliant on oxidative phosphorylation (OXPHOS) for survival. Moreover, maintenance of OXPHOS is dependent on BCL2, creating a therapeutic opportunity to target LSCs using the BCL2 inhibitor drug venetoclax. While venetoclax-based regimens have indeed shown promising clinical activity, the emergence of drug resistance is prevalent. Thus, in the present study, we investigated how mitochondrial properties may influence mechanisms that dictate venetoclax responsiveness. Our data show that utilization of mitochondrial calcium is fundamentally different between drug responsive and non-responsive LSCs. By comparison, venetoclax-resistant LSCs demonstrate a more active metabolic (i.e., OXPHOS) status with relatively high steady-state levels of calcium. Consequently, we tested genetic and pharmacological approaches to target the mitochondrial calcium uniporter, MCU. We demonstrate that inhibition of calcium uptake sharply reduces OXPHOS and leads to eradication of venetoclax-resistant LSCs. These findings demonstrate a central role for calcium signaling in the biology of LSCs and provide a therapeutic avenue for clinical management of venetoclax resistance.

ASSET: Auto-Segmentation of the Seventeen SEgments for Ventricular Tachycardia Ablation in Radiation Therapy.

There has been a recent effort to treat high-risk ventricular tachycardia (VT) patients through radio-ablation. However, manual segmentation of the VT target is complex and time-consuming. This work introduces ASSET, or Auto-segmentation of the Seventeen SEgments for Tachycardia ablation, to aid in radiation therapy (RT) planning. ASSET was retrospectively applied to CTs for 26 thoracic RT patients (13 undergoing VT ablation). The physician-defined parasternal long-axis of the left ventricle (LV) and the axes generated from principal component analysis (PCA) were compared using mean distance to agreement (MDA) and angle of separation. The manually selected right ventricle insertion point and LVs were used to apply the ASSET model to automatically generate the 17 segments of the LV myocardium (LVM). Physician-defined parasternal long-axis differed from PCA by 1.2 ± 0.3 mm MDA and 6.9 ± 0.7 degrees. Segments differed by 0.69 ± 0.29 mm MDA and 0.89 ± 0.03 Dice similarity coefficient. Running ASSET takes <5 min where manual segmentation took >2 h/patient. Agreement between ASSET and expert contours was comparable to inter-observer variability. Qualitative scoring conducted by three experts revealed automatically generated segmentations were clinically useable as-is. ASSET offers efficient and reliable automatic segmentations for the 17 segments of the LVM for target generation in RT planning.

A Novel Type of Monocytic Leukemia Stem Cell Revealed by the Clinical Use of Venetoclax-Based Therapy.

The BCL2 inhibitor venetoclax has recently emerged as an important component of acute myeloid leukemia (AML) therapy. Notably, use of this agent has revealed a previously unrecognized form of pathogenesis characterized by monocytic disease progression. We demonstrate that this form of disease arises from a fundamentally different type of leukemia stem cell (LSC), which we designate as monocytic LSC (m-LSC), that is developmentally and clinically distinct from the more well-described primitive LSC (p-LSC). The m-LSC is distinguished by a unique immunophenotype (CD34-, CD4+, CD11b-, CD14-, CD36-), unique transcriptional state, reliance on purine metabolism, and selective sensitivity to cladribine. Critically, in some instances, m-LSC and p-LSC subtypes can co-reside in the same patient with AML and simultaneously contribute to overall tumor biology. Thus, our findings demonstrate that LSC heterogeneity has direct clinical significance and highlight the need to distinguish and target m-LSCs as a means to improve clinical outcomes with venetoclax-based regimens. SIGNIFICANCE: These studies identify and characterize a new type of human acute myeloid LSC that is responsible for monocytic disease progression in patients with AML treated with venetoclax-based regimens. Our studies describe the phenotype, molecular properties, and drug sensitivities of this unique LSC subclass. This article is featured in Selected Articles from This Issue, p. 1949.

Venetoclax is safe and tolerable as post-transplant maintenance therapy for AML patients at high risk for relapse.

Relapse is the most common cause of mortality in acute myeloid leukemia (AML) patients after allogeneic stem cell transplant (SCT). Post-SCT maintenance strategies that prevent relapse are desirable but must be well tolerated and convenient to administer. We hypothesized single agent venetoclax (ven) may be an effective maintenance therapy among high relapse risk patients. Between February 2019 and December 2021, we administered post-SCT ven maintenance to 49 AML patients at high-risk for relapse as a prospectively defined off-label practice at our institution. Ven was planned to be administered until 1-year post-SCT. While temporary interruptions were common (67.3% of all patients), of those with >1 year follow up, 22/25 (88%) completed the full year of planned therapy. Cytopenias (40.8%) and gastrointestinal adverse events (34.7%) were the most common toxicities. At 1-year post-SCT, overall survival (OS) and relapse-free survival (RFS) were 70% and 67% respectively. Our experience demonstrates single agent ven is a safe, tolerable, and feasible maintenance therapy that may improve RFS and OS in high relapse risk post-SCT patients.

Higher-dose venetoclax with measurable residual disease-guided azacitidine discontinuation in newly diagnosed acute myeloid leukemia.

Venetoclax+azacitidine is the standard of care for newly-diagnosed patients with acute myeloid leukemia (AML) for whom intensive chemotherapy is inappropriate. Efforts to optimize this regimen are necessary. We designed a clinical trial to investigate two hypotheses: i) higher doses of venetoclax are tolerable and more effective, and ii) azacitidine can be discontinued after deep remissions. Forty-two newly diagnosed AML patients were enrolled in the investigator-initiated High Dose Discontinuation Azacitidine+Venetoclax (HiDDAV) Study (clinicaltrials gov. Identifier: NCT03466294). Patients received one to three "induction" cycles of venetoclax 600 mg daily with azacitidine. Responders received MRD-positive or MRDnegative "maintenance" arms: azacitidine with 400 mg venetoclax or 400 mg venetoclax alone, respectively. The toxicity profile of HiDDAV was similar to 400 mg venetoclax. The overall response rate was 66.7%; the duration of response (DOR), event-free survival (EFS) and overall survival were 12.9, 7.8 and 9.8 months, respectively. The MRD negativity rate was 64.3% by flow cytometry and 25.0% when also measured by droplet digital polymerase chain recation. MRD-negative patients by flow cytometry had improved DOR and EFS; more stringent measures of MRD negativity were not associated with improved OS, DOR or EFS. Using MRD to guide azacitidine discontinuation did not lead to improved DOR, EFS or OS compared to patients who discontinued azacitidine without MRD guidance. Within the context of this study design, venetoclax doses >400 mg with azacitidine were well tolerated but not associated with discernible clinical improvement, and MRD may not assist in recommendations to discontinue azacitidine. Other strategies to optimize, and for some patients, de-intensify, venetoclax+azacitidine regimens are needed.

Transcriptomic Heterogeneity in High-risk Prostate Cancer and Implications for Extraprostatic Disease at Presentation on Prostate-specific Membrane Antigen Positron Emission Tomography.

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) has greater specificity and sensitivity for detection of extraprostatic prostate cancer (PCa) at presentation than conventional imaging. Although the long-term clinical significance of acting on these findings is unknown, it has been shown that the risk of upstaging is prognostic for long-term outcomes in men with high-risk (HR) or very high-risk (VHR) PCa. We evaluated the association between the risk of upstaging on PSMA PET and the Decipher genomic classifier score, a known prognostic biomarker in localized PCa that is being evaluated for its predictive ability to direct systemic therapy intensification. In a cohort of 4625 patients with HR or VHR PCa, the risk of upstaging on PSMA PET was significantly correlated with the Decipher score (p < 0.001). These results should be seen as hypothesis-generating and warrant further studies on the causal pathways linking PSMA findings, Decipher scores, extraprostatic disease, and long-term clinical outcomes. PATIENT SUMMARY: We found significant correlation between the risk of having prostate cancer outside the prostate gland on a sensitive scan (based on prostate-specific membrane antigen [PSMA]) at initial staging and the Decipher genetic score. The results warrant further studies on the causal pathways between PSMA scan findings, Decipher scores, disease outside the prostate, and long-term outcomes.

Appropriateness of cardiovascular computed tomography and magnetic resonance imaging in patients with conotruncal defects.

BACKGROUND: To promote the rational use of cardiovascular imaging in patients with congenital heart disease, the American College of Cardiology developed Appropriate Use Criteria (AUC), but its clinical application and pre-release benchmarks have not been evaluated. We aimed to evaluate the appropriateness of indications for cardiovascular magnetic resonance (CMR) and cardiovascular computed tomography (CCT) in patients with conotruncal defects and to identify factors associated with maybe or rarely appropriate (M/R) indications. METHODS: Twelve centers each contributed a median of 147 studies performed prior to AUC publication (01/2020) on patients with conotruncal defects. To incorporate patient characteristics and center-level effects, a hierarchical generalized linear mixed model was used. RESULTS: Of the 1753 studies (80% CMR, and 20% CCT), 16% were rated M/R. Center M/R ranged from 4 to 39%. Infants accounted for 8.4% of studies. In multivariable analyses, patient- and study-level factors associated with M/R rating included: age <1 year (OR 1.90 [1.15-3.13]), truncus arteriosus (vs. tetralogy of Fallot, OR 2.55 [1.5-4.35]), and CCT (vs. CMR, OR 2.67 [1.87-3.83]). None of the provider- or center-level factors reached statistical significance in the multivariable model. CONCLUSIONS: Most CMRs and CCTs ordered for the follow-up care of patients with conotruncal defects were rated appropriate. However, there was significant center-level variation in appropriateness ratings. Younger age, CCT, and truncus arteriosus were independently associated with higher odds of M/R rating. These findings could inform future quality improvement initiatives and further exploration of factors resulting in center-level variation.

Brief Report: Severe Pneumonitis After Combined Thoracic Radiotherapy and Osimertinib.

Introduction: Osimertinib is an effective treatment for metastatic NSCLC. Occasionally, thoracic radiation therapy (TRT) is delivered to patients receiving osimertinib to treat residual or progressing pulmonary tumors. Anecdotal reports suggest that the delivery of TRT in combination with osimertinib may be associated with a high risk of severe pneumonitis. Methods: A retrospective study was performed at a single academic medical center in the United States to investigate the incidence of severe pneumonitis among patients treated with combined TRT and osimertinib between June 2016 and December 2021. Baseline patient characteristics, tumor size and location, and dosimetric parameters were evaluated. The highest grade of radiation pneumonitis that developed within 6 months of treatment was scored in accordance with the Common Terminology Criteria for Adverse Events version 5.0. Results: A total of 16 patients were identified who were treated with combined TRT and osimertinib. All had a diagnosis of metastatic NSCLC. Treatment-related grade greater than or equal to 2 pneumonitis developed in 56%, grade greater than or equal to 3 in 37.5%, and grade 4 in 6.3%; no patient developed grade 5 pneumonitis. Median time to any-grade pneumonitis was 29 days (1-84 d); all patients had symptom resolution with expectant management or oral steroid therapies. All patients discovered to have grade greater than or equal to 3 pneumonitis (n = 6) received TRT to tumors located within 2 cm of the proximal bronchial tree, including tumors abutting the proximal bronchial tree (n = 2) and within the mediastinum (n = 1). Conclusions: The combination of TRT with osimertinib was associated with a high rate of severe pneumonitis that required oral steroid medications. Larger studies are needed to validate these findings and to understand the clinical and treatment factors that influence this risk and how they can be mitigated.

Organoid generation from mouse mammary tumors captures the genetic heterogeneity of clinically relevant copy number alterations.

Breast cancer metastases exhibit many different genetic alterations, including copy number amplifications. Using publicly available datasets, we identify copy number amplifications in metastatic breast tumor samples and using our organoid-based metastasis assays, and we validate FGFR1 is amplified in collectively migrating organoids. Because the heterogeneity of breast tumors is increasingly becoming relevant to clinical practice, we demonstrate our organoid method captures genetic heterogeneity of individual tumors.

68Ga-PSMA PET/CT-Based Atlas for Prostate Bed Recurrence After Radical Prostatectomy: Clinical Implications for Salvage Radiation Therapy Contouring Guidelines.

The aim of this study was to analyze the patterns of prostate bed (PB) recurrence in prostate cancer patients experiencing prostate-specific antigen (PSA) persistence (BCP) or biochemical recurrence (BCR) after radical prostatectomy using 68Ga-PSMA-11 PET/CT (68Ga-PSMA PET) in relation to the Radiation Therapy Oncology Group (RTOG) clinical target volumes (CTVs). Methods: This single-center, retrospective analysis included patients with BCP or BCR after radical prostatectomy and PB recurrence on 68Ga-PSMA PET. The PB recurrences were delineated by nuclear medicine physicians, the CTVs by radiation oncologists contouring guidelines on the 68Ga-PSMA PET, respectively, masked from each other. The coverage of the 68Ga-PSMA PET recurrence was categorized as PSMA recurrence completely covered, partially covered, or not covered by the RTOG-based CTV. Further, we evaluated the differences in PSMA recurrence patterns among patients with different 68Ga-PSMA PET staging (miTNM). Mann-Whitney U tests, the chi-square test, and Spearman (ρ) correlation analysis were used to investigate associations between CTV coverage and 68Ga-PSMA PET-based tumor volume, serum PSA levels, miTNM, and rectal/bladder involvement. Results: A total of 226 patients were included in the analysis; 127 patients had PSMA recurrence limited to the PB (miTrN0M0), 30 had pelvic nodal disease (miTrN1M0), 32 had extrapelvic disease (miTrN0M1), and 37 had both pelvic nodal disease and extrapelvic disease (miTrN1M1). In the miTrN0M0 cohort, the recurrence involved the rectal and bladder walls in 12 of 127 (9%) and 4 of 127 (3%), respectively. The PSMA-positive PB recurrences were completely covered by the CTV in 68 of 127 patients (53%), partially covered in 43 of 127 (34%), and not covered in 16 of 127 (13%). Full coverage was associated with a smaller tumor volume (P = 0.043), a lack of rectal/bladder wall involvement (P = 0.03), and lower miTNM staging (P = 0.035) but not with lower serum PSA levels (P = 0.979). Conclusion: Our study suggests that 68Ga-PSMA PET can be a valuable tool for guiding salvage radiation therapy (SRT) planning directed to the PB in the setting of postoperative BCR or BCP. These data should be incorporated into the redefinition of PB contouring guidelines.

A Multisite Retrospective Review of Direct Oral Anticoagulants Compared to Warfarin in Adult Fontan Patients.

PURPOSE: Direct oral anticoagulants (DOACs) are not recommended in adult Fontan patients (Level of Evidence C). We hypothesized that DOACs are comparable to warfarin and do not increase thrombotic and embolic complications (TEs) or clinically significant bleeds. METHODS: We reviewed the medical records of adult Fontan patients on DOACs or warfarin at three major medical centers. We identified 130 patients: 48 on DOACs and 107 on warfarin. In total, they were treated for 810 months on DOACs and 5637 months on warfarin. RESULTS: The incidence of TEs in patients on DOACs compared to those on warfarin was not increased in a statistically significant way (hazard ratio [HR] 1.7 and p value 0.431). Similarly, the incidence of nonmajor and major bleeds in patients on DOACs compared to those on warfarin was also not increased in a statistically significant way (HR for nonmajor bleeds in DOAC patients was 2.8 with a p value of 0.167 and the HR for major bleeds was 2.0 with a p value 0.267). In multivariate analysis, congestive heart failure (CHF) was a risk factor for TEs across both groups (odds ratio [OR] = 4.8, 95% confidence interval [CI] = 1.3-17.6) and bleed history was a risk factor for clinically significant bleeds (OR = 6.8, 95% CI = 2.7-17.2). CONCLUSION: In this small, retrospective multicenter study, the use of DOACs did not increase the risk of TEs or clinically significant bleeds compared to warfarin in a statistically significant way.