Abstract. In Houston, we have been monitoring the immune response to West Nile virus (WNV) infection in a large cohort of study participants since 2002. Using enzyme-linked immunosorbent assay techniques, serum from 163 participants was tested for the presence of anti-WNV immunoglobulin M (IgM) and IgG antibodies. We found that 42%, 34%, and 23% of study participants had either positive or equivocal results when tested for anti-WNV IgM antibodies approximately 1, 6, and 8 years post-infection, respectively. Conversely, almost one-half of study participants (46%) had undetectable anti-WNV IgG antibodies by 8 years post-infection. This study is the first study to calculate the slope of the rate of decay of antibodies over time as well as show persistence of detectable anti-WNV IgM antibodies up to 8 years post-infection. These findings warrant additional investigation, particularly the determination of whether persistence of IgM is related to persistent infection with WNV.

Romosozumab is a monoclonal antibody that inhibits sclerostin and has been shown to reduce the risk of fractures within 12 months. In a phase II, randomized, placebo-controlled clinical trial of treatment-na€ ıve postmenopausal women with low bone mass, romosozumab increased bone mineral density (BMD) at the hip and spine by the dual effect of increasing bone formation and decreasing bone resorption. In a substudy of that trial, which included placebo and teriparatide arms, here we investigated whether those observed increases in BMD also resulted in improvements in estimated strength, as assessed by finite element analysis. Participants received blinded romosozumab s.c. (210 mg monthly) or placebo, or open-label teriparatide (20 mg daily) for 12 months. CT scans, obtained at the lumbar spine (n ¼ 82) and proximal femur (n ¼ 46) at baseline and month 12, were analyzed with finite element software (VirtuOst, O.N. Diagnostics) to estimate strength for a simulated compression overload for the spine (L 1 vertebral body) and a sideways fall for the proximal femur, all blinded to treatment assignment. We found that, at month 12, vertebral strength increased more for romosozumab compared with both teriparatide (27.3% versus 18.5%; p ¼ 0.005) and placebo (27.3% versus -3.9%; p < 0.0001); changes in femoral strength for romosozumab showed similar but smaller changes, increasing more with romosozumab versus teriparatide (3.6% versus -0.7%; p ¼ 0.027), and trending higher versus placebo (3.6% versus À0.1%; p ¼ 0.059). Compartmental analysis revealed that the bone-strengthening effects for romosozumab were associated with positive contributions from both the cortical and trabecular bone compartments at both the lumbar spine and hip. Taken together, these findings suggest that romosozumab may offer patients with osteoporosis a new bone-forming therapeutic option that increases both vertebral and femoral strength within 12 months.

Epstein-Barr virus (EBV) infection of primary B cellsleads to the outgrowth of indefinitely proliferating lymphoblastoid cell lines (LCLs). However, the efficiency of immortalization is less than 10% of infected cells. We hypothesize that a robust innate tumor suppressor response prevents long-term outgrowth of the majority of infected cells. In this study we identify the DNA damage response (DDR) as a major component of this response. EBV infection of primary B cells activated hallmarks of the DDR including phosphorylated ATM, Chk2, g-H2AX, and 53BP1 foci. DDR activation was not due to lytic viral DNA replication nor did its marks co-localize with latent viral episomes. Rather, EBV induced a period of hyper-proliferation early after infection responsible for DDR activation. Microarray data supported the transient activation and subsequent attenuation of proliferation and DDR-associated mRNAs during LCL outgrowth. Importantly, activation of this pathway suppressed transformation as small molecule antagonism of the DNA damage responsive kinases ATM and Chk2 increased EBV transformation efficiency. Thus, we propose a model whereby EBV infection initially drives aberrant cellular DNA replication activating an anti-proliferative DNA damage response. Long-term outgrowth depends on attenuation of this hyper-proliferative signal through full latency III gene expression. AcknowledgementsThis article has been published as part of Infectious

Background: AKT pathway activation has been implicated in the development of endocrine therapy resistance in hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2–) advanced breast cancer (ABC). In the Phase II, placebo (PBO)-controlled FAKTION trial, the addition of the pan-AKT inhibitor capivasertib to fulvestrant significantly improved progression-free survival (PFS) and overall survival in postmenopausal women with aromatase inhibitor (AI)-resistant HR+/HER2– ABC. The Phase III, randomized, double-blind, PBO-controlled CAPItello-291 trial (NCT04305496) investigated the efficacy and safety of capivasertib + fulvestrant in patients with AI-resistant HR+/HER2– ABC. Methods: Eligible pre/peri or postmenopausal women or men with HR+/HER2– ABC that had recurred or progressed on or after AI therapy with or without a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor were randomized 1:1 to receive fulvestrant (per standard dosing schedule) with either PBO or capivasertib (400 mg twice daily; 4 days on, 3 days off). Randomization was stratified by the presence of liver metastases, prior use of CDK4/6 inhibitors, and geographic location. AKT pathway alteration status (at least one qualifying PIK3CA, AKT1, or PTEN alteration) was determined using next-generation sequencing in tumor tissue. The dual primary endpoint was investigator-assessed PFS in the overall population and in patients with AKT pathway-altered tumors. Results: A total of 708 patients were randomized: 355 to capivasertib + fulvestrant and 353 to PBO + fulvestrant. Overall, 41% of patients had AKT pathway-altered tumors (48% [n=289/602] of patients with tumor sequencing results), 22% were pre/perimenopausal and 77% postmenopausal, with 1% male. Prior therapy for advanced disease included: 87% of patients with ≥1 line of prior treatment, 69% with a prior CDK4/6 inhibitor, and 18% with prior chemotherapy. Demographic and baseline characteristics were broadly balanced between the overall and altered populations and by treatment groups. At primary analysis (data cut-off Aug 15, 2022), 551 and 236 PFS events had occurred in the overall and pathway-altered populations, respectively. Overall, the median PFS was 7.2 months with capivasertib + fulvestrant and 3.6 months with PBO + fulvestrant (hazard ratio [HR] 0.60; 95% confidence interval [CI] 0.51–0.71; p&lt;0.001). In patients with AKT pathway-altered tumors, median PFS was 7.3 months with capivasertib + fulvestrant and 3.1 months with PBO + fulvestrant (HR 0.50; 95% CI 0.38–0.65; p&lt;0.001). The objective response rate in patients with measurable disease was 22.9% for capivasertib + fulvestrant vs 12.2% for PBO + fulvestrant overall and 28.8% vs 9.7% in the AKT pathway-altered population. The most frequent all-grade adverse events (AEs) with capivasertib + fulvestrant were diarrhea (72.4% vs 20.0% PBO + fulvestrant arm), rash (group term of rash, rash macular, rash maculo-papular, rash papular, rash pruritic; 38.0% vs 7.1%) and nausea (34.6% vs 15.4%). The most frequently reported grade ≥3 AEs were rash (group term; 12.1% vs 0.3%), diarrhea (9.3% vs 0.3%), and hyperglycemia (2.3% vs 0.3%); grade ≥3 stomatitis was 2.0% vs 0%. AEs leading to discontinuation of capivasertib/placebo were reported in 13.0% and 2.3% of patients, respectively. Conclusions: Capivasertib + fulvestrant significantly improved PFS compared to fulvestrant alone in the overall population, and in patients with AKT pathway-altered tumors, and may become a future treatment option in this setting. The safety profile of capivasertib + fulvestrant was generally manageable and consistent with prior data. Funding: CAPItello-291 is sponsored by AstraZeneca. Editorial acknowledgment: AstraZeneca-funded medical writing support was provided by Suzanne Patel, Ph.D., from BOLDSCIENCE Inc. Capivasertib was discovered by AstraZeneca subsequent to a collaboration with Astex Therapeutics (and its collaboration with the Institute of Cancer Research and Cancer Research Technology Limited). Citation Format: Nicholas Turner, Mafalda Oliveira, Sacha J. Howell, Florence Dalenc, Javier Cortés, Henry Gomez, Xichun Hu, Komal Jhaveri, Sibylle Loibl, Serafin Morales Murillo, Zbigniew Nowecki, Meena Okera, Yeon H. Park, Masakazu Toi, Lyudmila Zhukova, Chris Yan, Gaia Schiavon, Andrew Foxley, Hope Rugo. GS3-04 Capivasertib and fulvestrant for patients with aromatase inhibitor-resistant hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: results from the Phase III CAPItello-291 trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS3-04.

Introduction The phosphoinositide 3-kinase p110δ isoform (PI3Kδ) is expressed primarily in hematopoietic cells and is essential in B-cell receptor (BCR) signaling. PI3Kδ is expressed in lymphoid malignancies, including chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). AMG 319 is an investigational, highly selective, small molecule inhibitor of PI3Kδ that blocks B cell proliferation following BCR stimulation both in vitro and in vivo, inhibits basal AKT phosphorylation, and inhibits proliferation in lymphoid tumor cells. This study evaluated the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of AMG 319. Methods Patients (pts) with relapsed or refractory CLL or NHL were eligible. Key eligibility criteria included ≥ 18 years old, ECOG ≤ 2, and adequate organ function. AMG 319 was administered once per day (QD; except day 2 for PK) until disease progression or unacceptable toxicity. Doses of 25, 50, 100, 200, 300, and 400 mg were administered in sequential cohorts (3 pts per cohort). Dose-limiting toxicities (DLT) were defined during the first 28 days. Response assessments for CLL and NHL were done using IWCLL 2008 and IWG 2007 criteria, respectively. CT scans for CLL pts were done at baseline and week 8. Results 28 pts received AMG 319 (6 at 25 mg; 3 at 50 mg, 100 mg, 200 mg, and 300 mg; and 10 at 400 mg). Demographics: median age 68 years, 71% men, ECOG 0/1 93%. 25 pts had CLL, 3 had NHL, including 2 mantle cell and 1 marginal zone. The median number of prior treatment regimens was 4 (range 1-9) for CLL and 7 (range 5-9) for NHL. Central cytogenetic analysis of CLL pts prior to dosing (n=24) revealed 10 with del 17p (42%), 3 with del 11 and not 17p (13%), 1 with trisomy 12 alone (4%), 9 normal (38%), and 1 del 13q alone (4%). Doses up to 400 mg QD were explored without reaching a maximum tolerated dose. There was 1 DLT: grade 3 hemolytic anemia at 25 mg in a CLL pt after 1 dose, considered as possibly related to AMG 319. AMG 319 was well absorbed and exhibited linear PK with mean plasma half-lives of 3.8 to 6.6 hours across dose cohorts. Dose-dependent coverage of BCR-induced pAKT in CLL samples (ex-vivo IgD stimulated) was observed in all samples with an inducible signal (60%); near complete inhibition for 24 hours was seen at 400 mg. 75% of pts had ≥1 treatment-related adverse event (AE, 25% grade ≥3). Grade ≥3 treatment-related AEs (n>1) were colitis 3 (10%), anemia 3 (10%), leukocytosis 2 (7%), infection 2 (7%), and hemolysis 2 (7%). The colitis cases occurred at 400 mg between days 40 and 60; 2 were successfully re-challenged at a lower dose, while the third was diagnosed with C Diff colitis and discontinued. Grade 3 transaminitis was observed in 1 pt (4%) at 50 mg on day 29, which resolved with holding of drug and did not recur with re-challenge. Subset analysis of lymphocytes revealed no changes in % of T, B, or NK cells. Baseline % of T-regulatory cells (as a function of total CD4) was elevated in CLL pts (14.4% ± 7.6%). Elevated T regulatory cells (>10% of CD4+) tended to normalize during treatment (14/19 pts), suggesting immune restoration. Response data are available for 24 CLL pts (pt with DLT removed after 1 dose) and 3 NHL pts. Lymphocyte counts in CLL were highly variable, with some pts experiencing marked and early lymphocytosis (at all doses) and others showing gradual decline. Consistent nodal regression was observed at all doses by CT and physical exam. Early CT imaging (21 pts) at week 8 revealed lymph node (LN) reduction in all pts, and >50% decrease was seen in 7 pts; all 7 were dosed at 400 mg including 4 with del 17p or del 11q. Two pts at week 8 met IWCLL response criteria for partial response. By physical exam, all 20 evaluable pts had >50% LN reduction as a best response, with 15 (75%) having >90%. Response was present in all cytogenetic subtypes. At the 200-400 mg dose levels, 13/15 CLL pts remain on study after a median follow-up of 30 weeks (range 14-65). 1 pt with mantle cell NHL had 46% shrinkage while on therapy but progressed after 26 weeks; the 2 other NHL pts progressed by the first evaluation. Conclusions AMG 319 exhibited linear absorption and was tolerated at doses up to 400 mg QD. This degree of inhibition provided complete blockade of ex-vivo stimulated pAKT for 24 hours in CLL. Anti-tumor activity was observed early in CLL pts and included high-risk cytogenetic subgroups. While activity was noted at all dose levels, an apparent dose response was observed, with deeper and faster responses in CLL pts at higher doses. Disclosures: Lanasa: Amgen: Consultancy. Glenn:Amgen: Research Funding; Sanofi Aventis: Research Funding. Mato:Amgen: Honoraria. Wong:Amgen: Employment, Equity Ownership. Amore:Amgen: Employment, Equity Ownership. Means:Amgen: Employment, Equity Ownership. Stevens:Amgen: Employment, Equity Ownership. Yan:Amgen: Employment, Equity Ownership. Friberg:Amgen: Employment, Equity Ownership. Goy:Amgen Inc: Research Funding.