Blood Eosinophilia Is an on-Treatment Biomarker in Patients with Solid Tumors Undergoing Dendritic Cell Vaccination with Autologous Tumor-RNA

Background: The approvals of immune checkpoint inhibitors for several cancer types and the rapidly growing recognition that T cell-based immunotherapy significantly improves outcomes for cancer patients led to a re-emergence of cancer vaccines, including dendritic cell (DC)-based immunotherapy. Blood and tissue biomarkers to identify responders and long-term survivors and to optimize cost and cost-effectiveness of treatment are greatly needed. We wanted to investigate whether blood eosinophilia is a predictive biomarker for patients with solid tumors receiving vaccinations with DCs loaded with autologous tumor-RNA. Methods: In total, 67 patients with metastatic solid tumors, who we treated with autologous monocyte-derived DCs transfected with total tumor mRNA, were serially analyzed for eosinophil counts and survival over the course of up to 14 years. Eosinophilic counts were performed on peripheral blood smears. Results: Up to 87% of the patients treated with DC-based immunotherapy experienced at least once an eosinophilia of ≥ 5% after initiation of therapy; 61 % reached levels of ≥ 10% eosinophils, and 13% of patients showed eosinophil counts of 20% or above. While prevaccination eosinophil levels were not associated with survival, patients with blood eosinophilia at any point after initiation of DC-based immunotherapy showed a trend towards longer survival. There was a statistically significant difference for the patients with eosinophil counts of 20% or more (p = 0.03). In those patients, survival was prolonged to a median of 58 months (range 2–111 months), compared to a median of 20 months (range 0–119 months) in patients with lower eosinophil counts. In 12% of the patients, an immediate increase in eosinophil count of at least 10 percentage points could be detected after the first vaccine, which also appeared to correlate with survival (65 vs. 24 months; p = 0.06). Conclusion: Blood eosinophilia appears to be an early, on-therapy biomarker in patients with solid tumors undergoing vaccination with RNA-transfected DC, specifically autologous tumor mRNA-transfected DC vaccines, and it correlates with long-term patient outcome. Eosinophilia should be systematically investigated in future trials.

Therapeutic Cancer Vaccination with Ex Vivo RNA-Transfected Dendritic Cells—An Update

Over the last two decades, dendritic cell (DC) vaccination has been studied extensively as active immunotherapy in cancer treatment and has been proven safe in all clinical trials both with respect to short and long-term side effects. For antigen-loading of dendritic cells (DCs) one method is to introduce mRNA coding for the desired antigens. To target the whole antigenic repertoire of a tumor, even the total tumor mRNA of a macrodissected biopsy sample can be used. To date, reports have been published on a total of 781 patients suffering from different tumor entities and HIV-infection, who have been treated with DCs loaded with mRNA. The majority of those were melanoma patients, followed by HIV-infected patients, but leukemias, brain tumors, prostate cancer, renal cell carcinomas, pancreatic cancers and several others have also been treated. Next to antigen-loading, mRNA-electroporation allows a purposeful manipulation of the DCs’ phenotype and function to enhance their immunogenicity. In this review, we intend to give a comprehensive summary of what has been published regarding clinical testing of ex vivo generated mRNA-transfected DCs, with respect to safety and risk/benefit evaluations, choice of tumor antigens and RNA-source, and the design of better DCs for vaccination by transfection of mRNA-encoded functional proteins.

PNN and KCNQ1OT1 can predict the efficacy of adjuvant fluoropyrimidine-based chemotherapy in colorectal cancer patients

The benefit of adjuvant chemotherapy in early stages of colorectal cancer (CRC) is still disappointing and the prediction of treatment outcome quite difficult. Recently, through a transcriptomic approach, we evidenced a role of PNN and KCNQ1OT1 gene expression in predicting response to fluoropyrimidine-based adjuvant chemotherapy in stage III CRC patients. Thus, the aim of this study was to validate in an independent cohort of stage II-III CRC patients our previous findings. PNN and KCNQ1OT1 mRNA expression levels were evaluated in 74 formalin fixed paraffin-embedded tumor and matched normal mucosa samples obtained by stage II-III CRC patients treated with fluoropyrimidine-based adjuvant chemotherapy. PININ, the protein encoded by PNN, was immunohistochemically evaluated in 15 tumor and corresponding normal mucosa samples, selected on the basis of a low, medium or high mRNA expression tumor/mucosa ratio. PNN and KCNQ1OT1 mRNA mean expression levels were significantly higher in tumor compared with normal tissues. Patients with high PNN or KCNQ1OT1 tumor mRNA levels according to ROC-based cut-offs, showed a shorter disease-free survival (DFS) compared with patients with low tumor mRNA gene expression. Also, patients with tumor mRNA expression values of both genes below the identified cut-offs had significantly longer DFS compared with patients with the expression of one or both genes above the cut-offs. In a representative large cohort of stage II-III CRC untreated patients retrieved from GEO datasets, no difference in DFS was observed between patients with high and low PNN or KCNQ1OT1 gene expression levels. These data confirm our previous findings and underscore the relevance of PNN and KCNQ1OT1 expression in predicting DFS in early stages of CRC treated with fluoropyrimidine-based adjuvant chemotherapy. If further validated in a prospective case series, both biomarkers could beCopyright © 2020 Cognizant Communication CorporationEU-3350 Oncology Research E-pub 3used to identify patients who benefit from this treatment and to offer alternative chemotherapy regimens to potential unresponsive patients. In relation to the suggested biological role of PNN and KCNQ1OT1 in CRC, they might also be exploited as potential therapeutic targets.

IMMU-47. RNA-NANOPARTICLE VACCINES ARE SAFE AND IMMUNOLOGICALLY ACTIVE IN CLIENT-OWNED CANINES WITH TERMINAL GLIOMAS

BACKGROUND The lack of appropriate preclinical murine glioblastoma models limits comprehensive toxicity/efficacy evaluation of investigational agents. To overcome this challenge, we evaluated the safety and activity of a new immunotherapeutic technology that we have pioneered (composed of tumor mRNA complexed into a custom lipid-nanoparticle formulation) in client-owned canines (pet dogs) diagnosed with malignant gliomas. OBJECTIVE/ METHODS Canine malignant gliomas were biopsied for generation of personalized tumor mRNA loaded into our custom lipid-nanoparticle (NP) vector. The patients received RNA-NPs intravenously beginning two weeks after their biopsy once weekly (x3) and no other anti-tumor therapeutic interventions. RESULTS Within a few hours after administration, tumor specific RNA-NPs elicited margination of peripheral blood mononuclear cells, which increased in the subsequent days/weeks post-treatment; suggesting that RNA-NPs mediate lymphoid honing of immune cell populations before egress. RNA-NPs also elicited increased: 1) serum interferon-α that spiked at 2 hours; 2) CD80 and MHCII on CD11c+ cells (demonstrating activation of peripheral DCs); and 3) interferon-γ + T-cells (i.e. activated T-cells). After receiving weekly RNA-NPs (×3), the canines had a steady course. Aside from low-grade fevers on the vaccination days, personalized tumor RNA-NPs (1x) were well tolerated with stable blood counts, chemistries, and renal/liver function tests. All patients assessed developed immunologic response with pseudoprogression or stable/smaller tumors by MRI. Although we have treated a small cohort, we have observed improvement in median/overall survival in all canine patients with terminal gliomas receiving RNA-NPs (compared with historical controls). CONCLUSION RNA-NPs were feasible, safe and immunologically active in client-owned canines with terminal gliomas. We have not appreciated significant toxicities in canines that would preclude investigation in humans at 1x dosing. Although these results need to be validated in larger canine data sets, these results suggest safety and activity of tumor specific RNA-NPs in canines with terminal gliomas.

Early clinical experience with the pan-FGFR inhibitor rogaratinib in patients with non-small cell lung cancer selected based on FGFR mRNA expression levels.

e20661 Background: FGFR1 gene amplifications are observed in squamous (sq) non-small cell lung cancer (NSCLC) and may suggest tractable oncogenic dependency. However, their value in predicting clinical activity of FGFR inhibitors is unclear. We explored tumor FGFR1-3 mRNA expression levels to select patients (pts) for treatment with rogaratinib, an oral, potent, small-molecule inhibitor of FGFR1-4. The first-in-human study of rogaratinib included pts with all NSCLC histologies. Methods: Pts with refractory advanced NSCLC were screened for elevated FGFR1-3 mRNA levels by RNA in situ hybridization (RNAscope) and NanoString assay in fresh or archival tumor samples, and FGFR1-3 overexpression was defined by pre-specified cut-offs. Pts received rogaratinib 800 mg BID on a continuous 21-day cycle. Tumor response was assessed by Response Evaluation Criteria in Solid Tumors v1.1 after cycles 2, 5, and 8. Results: 260 NSCLC biopsies were screened for FGFR1-3 tumor mRNA expression; 244 (93.8%) were evaluable. FGFR1-3 mRNA overexpression was found in 47% of sq NSCLC, and only 14% of non-sq NSCLC, with FGFR3 being the most commonly overexpressed subtype. 40 FGFR mRNA-positive pts were enrolled and treated. Rogaratinib was well tolerated; hyperphosphatemia (75%), diarrhea (53%), and decreased appetite (35%) were the most frequent treatment-emergent adverse events. Events were mostly mild or moderate. 36 treated pts were evaluable for response. The overall response rate was 5.6% (2 partial responses, 1 lasting for > 16 months). Disease control rate was 64%. Disease stabilization was seen in pts with mRNA overexpression across all FGFR subtypes and also in pts who failed prior lines of therapy, including anti-PD-L1. Molecular studies are ongoing to identify additional predictors of response to improve pt selection. Conclusions: Rogaratinib has a favorable safety and tolerability profile and clinical activity in pts with refractory FGFR1-3 tumor mRNA-positive NSCLC. It has potential for further exploration in combination with other agents. A clinical trial is currently enrolling FGFR mRNA-overexpressing pts with advanced and pre-treated sq NSCLC. Clinical trial information: NCT03762122.