Cesar Castro

Hypoxia induced VEGF secretion promotes resistance to bispecific T-cell engagers

Abstract Bispecific T-cell Engagers (BITEs) are a novel form of immunotherapy that overcome a deficiency of immune checkpoint inhibitors (ICI) by targeting a preidentified tumor associated antigen and redirecting a polyclonal population of effector T-cells against the tumor. High grade serous ovarian cancer is a lethal disease in the recurrent setting and has not been amenable to ICI therapy. MUC16/CA125 is overexpressed in high grade serous ovarian cancer. BITEs targeting the tumor-retained portion of MUC16/CA125 have recently been described and are in early-phase clinical trials. To identify mechanisms of resistance to BITEs, we collected serum, peripheral blood mononuclear cells, and ascites samples from patients with disease progression on MUC16-directed bispecific antibodies. Analysis of these samples showed downregulation of MUC16/CA125, elevated secretion of VEGF, and epithelial-to-mesenchymal transition in tumor cells. Interestingly, hypoxia was determined to be a driver of these changes. These findings were prospectively validated in ovarian cancer cell lines with CRISPR/Cas9 knockout of MUC16/CA125 and VEGF. Peripheral blood mononuclear cells from patients with disease progression were capable of effective cytolysis ex vivo, suggesting that resistance to therapy was primarily tumor driven. Restoration of MUC16/CA125 expression did not restore cytotoxicity in the presence of increased VEGF secretion. Combination treatment with a VEGF inhibitor rescued cytotoxicity in hypoxia-conditioned ovarian cancer cell lines with preserved target antigen expression. Collectively, these data outline a link between hypoxia and the development of resistance to BITEs and posits inhibition of VEGF inhibition as a potentially important therapeutic intervention.

A Phase II, Two-Stage Study of Letrozole and Abemaciclib in Estrogen Receptor–Positive Recurrent Endometrial Cancer

PURPOSE Estrogen receptor (ER)–positive endometrial cancers (ECs) are characterized by phosphatidylinositol 3-kinase (PI3K) and receptor tyrosine kinase (RTK)/RAS/β-catenin (CTNNB1) pathway alterations in approximately 90% and 80% of cases, respectively. Extensive cross-talk between ER, PI3K, and RTK/RAS/CTNNB1 pathways leads to both ligand-dependent and ligand-independent ER transcriptional activity as well as upregulation of cyclin D1 which, in complex with cyclin-dependent kinases 4 and 6 (CDK4 and CDK6), is a critical regulator of cell cycle progression and a key mediator of resistance to hormonal therapy. We hypothesized that the combination of the aromatase inhibitor letrozole and CDK4/6 inhibitor abemaciclib would demonstrate promising activity in this setting. METHODS We conducted a phase II, two-stage study of letrozole/abemaciclib in recurrent ER-positive EC. Eligibility criteria included measurable disease, no limit on prior therapies, and all EC histologies; prior hormonal therapy was allowed. Primary end points were objective response rate by RECIST 1.1 and progression-free survival (PFS) rate at 6 months. RESULTS At the data cutoff date (December 03, 2021), 30 patients (28 with endometrioid EC) initiated protocol therapy; 15 (50%) patients had prior hormonal therapy. There were nine total responses (eight confirmed), for an objective response rate of 30% (95% CI, 14.7 to 49.4), all in endometrioid adenocarcinomas. Median PFS was 9.1 months, PFS at 6 months was 55.6% (95% CI, 35.1 to 72), and median duration of response was 7.4 months. Most common ≥ grade 3 treatment-related adverse events were neutropenia (20%) and anemia (17%). Responses were observed regardless of grade, prior hormonal therapy, mismatch repair, and progesterone receptor status. Exploratory tumor profiling revealed several mechanistically relevant candidate predictors of response ( CTNNB1, KRAS, and CDKN2A mutations) or absence of response ( TP53 mutations), which require independent validation. CONCLUSION Letrozole/abemaciclib demonstrated encouraging and durable evidence of activity in recurrent ER positive endometrioid EC.

Letrozole, abemaciclib and metformin in endometrial cancer: a non-randomized phase 2 trial

Based on preclinical studies showing synergism with simultaneous inhibition of the estrogen receptor (ER), CDK4/6 and PI3K pathways and based on window of opportunity studies showing that metformin suppresses PI3K/mTOR signaling in endometrial cancer (EC), we conduct a non-randomized phase 2 study of letrozole/abemaciclib/metformin in ER positive endometrioid EC (NCT03675893). Primary objectives include objective response rate (ORR) and rate of progression-free survival (PFS) at 6 months (PFS6) while secondary objectives include PFS, overall survival, duration of response and toxicity. Twenty-five patients initiate protocol therapy [letrozole 2.5 mg orally (PO) once a day (qd), abemaciclib 150 mg PO twice a day (bid) and metformin 500 mg PO qd]. ORR is 32% (3 complete and 5 partial responses, 95% CI 14.9%-53.5%), Kaplan Meier estimate of PFS6 is 69.8% (95% CI 46.9%-84.3%) and median PFS is 19.4 months (95% CI 5.7 months-not estimable). No patients discontinue therapy because of toxicity. There are no objective responses among TP53 mutated ECs and among NSMP (no specific molecular profile) tumors with RB1 or CCNE1 alterations; CTNNB1 mutations correlate with clinical benefit. Pharmacokinetic analyses demonstrate that administration of letrozole and abemaciclib with metformin result in a more than 3-fold increase in metformin exposure.

Empowering the on-site detection of nucleic acids by integrating CRISPR and digital signal processing

AbstractAddressing the global disparity in cancer care necessitates the development of rapid and affordable nucleic acid (NA) testing technologies. This need is particularly critical for cervical cancer, where molecular detection of human papillomavirus (HPV) has emerged as an accurate screening method. However, implementing this transition in low- and middle-income countries has been challenging due to the high costs and centralized facilities required for current NA tests. Here, we present CreDiT (CRISPR Enhanced Digital Testing) for on-site NA detection. The CreDiT platform integrates i) a one-pot CRISPR strategy that simultaneously amplifies both target NAs and analytical signals and ii) a robust fluorescent detection based on digital communication (encoding/decoding) technology. These features enable a rapid assay (<35 minutes) in a single streamlined workflow. We demonstrate the sensitive detection of cell-derived HPV DNA targets down to single copies and accurate identification of HPV types in clinical cervical brushing specimens (n = 121).

Diagnostic Accuracy of Serum P16ink4A and FOX‐P3 Concentrations for Detection of Cervical Lesions Among Women Attending a Cervical Cancer Clinic in Western Uganda: A Case‐Control Study

Introduction: Expression of P16ink4A and FOXP3 is correlated with the grades of cervical lesions. In this study, we determined the diagnostic accuracy of serum P16ink4A and FOXP3 concentrations for detection of cervical intraepithelial neoplasia (CIN) and cervical cancer (CC) in a rural setting in Southwestern Uganda. Material and Methods: CIN and CC cases (93 each before treatment), and 93 controls were identified. Clinical and demographic data were documented before quantifying serum P16ink4A and FOXP3 concentrations using quantitative ELISA kits. Cases were confirmed by cytology and/or histology. We employed descriptive statistics, cross‐tabulation, and receiver operating curves (ROC) using statistical software for data science (STATA) 17.  p ‐values <0.05 were considered statistically significant. Results: Serum FOXP3 concentration of 0.0545 ng/mL < showed moderate sensitivity (32.22% and 57.78%) for detection of CIN and CC from healthy controls, respectively. It also showed a moderately high specificity of 68.89% for detection of both CIN and CC from healthy controls (AUC‐0.6014 and 0.7679, respectively). Serum P16ink4A concentration of 0.946 ng/mL < showed moderate sensitivities (50.00% and 60.00%) and specificities (56.67% and 55.56%) for the detection of CIN and CC from healthy controls, respectively (AUC‐0.6085 and 0.7592, respectively). A combination of elevated serum FOXP3 and P16ink4A showed very low sensitivities of 18.89% in detecting CIN from healthy controls and 33.33% for detecting CC from healthy controls. This combination showed high specificity of 83.33% in detecting both CIN and CC from healthy controls (AUC‐0.5992 and 0.7642, respectively). Conclusion: Although serum P16ink4A and FOXP3 concentrations showed moderate accuracy, their combination was more specific than sensitive. This combination has a high potential to be applied for diagnosis rather than screening for cervical lesions, at least in the Ugandan population. Combinations of P16ink4A and FOXP3 with other biomarkers could improve diagnostic accuracies. Additionally, studies could be conducted to assess the performance of these biomarkers in the detection of cervical lesions in specific populations, say Human Immunodeficiency Virus (HIV)‐positive and HIV‐negative populations.

RESOLVE: Abemaciclib + Letrozole +/- Metformin, Zotatifin, or Gedatolisib in Endometrial or Low-Grade Serous Ovarian Cancer

This research study is studying a combination of targeted therapies as a possible treatment for estrogen-receptor positive (ER+) endometrial cancer and low-grade serous ovarian cancer. The drugs involved in this study are: * Abemaciclib (also known as Verzenio™) * Letrozole (also known as Femara®) * Metformin (also known as Glucophage®) * Zotatifin (also known as eFT226) * Gedatolisib (also known as PF-05212384)