Carmona, Jacqueline

Abstract BACKGROUND: The amplification of genes PDL-1, PDL-2, and JAK2 on chromosome 9p24, known as the PDJ amplicon, has been identified in 15% of triple negative breast cancer (TNBC) and is associated with tumor infiltrating lymphocytes and elevated JAK2 mRNA, suggesting a coordinated inflammatory response in TNBC. Adding pembrolizumab to chemotherapy in KEYNOTE trials 355 and 522 has validated the use of PD-1 blockade in TNBC and redefined the standard of care. Despite preclinical data suggesting a role for targeting the IL- 6/JAK2/STAT3 pathway, the JAK1/JAK2 inhibitor ruxolitinib has not shown efficacy as a single Agent in breast cancer. This is the first phase I clinical trial evaluating the combination of pembrolizumab and ruxolitinib in the treatment of metastatic TNBC. METHODS: We conducted a phase I clinical trial with accrual from 2018 to 2023 at Mayo Clinic Arizona. Patients (n=12) received 200 mg of IV pembrolizumab per cycle (every 3 weeks) with 3+3 dose escalation of oral ruxolitinib twice a day (dose level 0: 10 mg PO BID, level 1: 15 mg PO BID, level 2: 20 mg PO BID). The primary endpoint was to determine the maximum tolerated dose (MTD) of ruxolitinib and secondary endpoints were treatment safety and efficacy. Clinical response was assessed by computed tomography of the chest, abdomen, and pelvis every 3 cycles. PD-L1 expression in tumor was measured by immunohistochemistry (IHC). The effect of the combined therapies on T and B cell populations were assessed by flow cytometry and antibody profiling of 695 tumor antigens and 8 viral antigens by nucleic acid protein programmable array. RESULTS: Twelve female patients with chemotherapy refractory metastatic TNBC were treated on study. All received 200 mg IV pembrolizumab every cycle. Due to rapid disease progression of three patients early after treatment initiation, eligibility was restricted to prohibit patients with extensive pulmonary disease or elevated LDH. Those patients were excluded from efficacy or correlative analysis. The most common toxicities were transaminitis (n=12), anemia/leukopenia (n=12), and fatigue (n=9). The majority of adverse events were grade 1 and occurred at dose level 2. There were 5 adverse events grade 3 or higher: respiratory or thoracic complications (n=3), hypertension (n=1), and abdominal pain (n=1), but MTD was not established. The median number of cycles was 4 for each dose level (range n=2.0-9.0) and the median time to progression was 3 months (range n=1.4-6.3). No patient had tumor response by RECIST v1.1 criteria and there was no association of disease stability with PD-L1 tumor expression by IHC. Circulating antibodies to tumor antigens remained stable, and viral-specific antibodies mildly decreased by month 2 in all patients at dose levels 0 and 1. Of the 7 patients reactive to TRIM21 autoantibodies, 2 patients had a transient increase at 2 months. CONCLUSIONS: The combination of pembrolizumab with ruxolitinib was well tolerated at all dose levels, and the number but not the severity of adverse events increased with higher ruxolitinib dose. Two of six patients in dose level 0 and 1 had stable disease for six months on treatment, suggesting that the lower dose levels of ruxolitinib (i.e. 10 mg PO BID) may have more activity in combination with pembrolizumab. Citation Format: Anelia Kassi, Jacqueline Carmona, Sarah M. Green, Heidi Kosiorek, Michael T. Barrett, Barbara A. Pockaj, Donald Northfelt, Karen S. Anderson. Phase I trial of combination pembrolizumab and ruxolitinib in metastatic triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-18-07.

Abstract Vaccines to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induce antibody responses against the spike (S) protein. However, the continued emergence of variants such as Omicron (B.1.1.529), with 30 amino acid changes in the S protein, underscores the need to find conserved targets that induce adaptive immunity. Natural infection induces CD8+ T cell activation against the viral proteins S, membrane (M), and nucleocapsid (N) as well as NSPs (non-structural proteins). Our study seeks to find conserved and immunogenic MHC class I epitopes throughout the SARS-CoV-2 peptidome. We used Ensemble MHC, a novel consensus predictive algorithm to select highly immunogenic CD8+ T cell epitopes presented by 52 of the most common HLA-I alleles, covering > 98% of the world’s population. We selected 658 high confidence predicted peptides from the SARS-CoV-2 immunopeptidome and prioritized testing 108 structural epitopes derived from the S, M, N, and E proteins. We collected PBMCs from unexposed, healthy, and convalescent individuals (n=31) covering ~ 85% of HLA alleles in the population, and measured T cell immunity by IFNγ secretion ELISpot and Activation Induced Marker (AIM) flow cytometry. In convalescent individuals, all predicted epitopes tested so far (n=36) were immunogenic (IFNγ response >2 fold than background) but 3/19 tested donors were unreactive. Samples from pre-pandemic (2017–19) unexposed healthy donors are reactive to 42% of tested epitopes, which indicate cross-reactivity to common cold coronaviruses (CCC) and possibly pre-existing protection against SARS-CoV-2. In summary, we have identified 45 highly conserved and immunogenic SARS-CoV-2 CD8+ T cell epitopes as potential targets for vaccine design. Supported by a grant from the Arizona Department of Health Services (AZDHS)