Tumor infiltrating lymphocyte recruitment in patients with early stage breast cancer after intramammary IRX-2 cytokine immunotherapy

7 Background: The IRX-2 biologic is an injectable immunotherapy containing cytokines derived from stimulated lymphocytes. In preclinical models, IRX-2 activates T-cells, natural killer (NK) cells, macrophages, and dendritic cells, and facilitates maturation of antigen-presenting cells. Stromal tumor-infiltrating lymphocytes (sTILs) are associated with improved outcomes in early stage breast cancer (ESBC), and neoadjuvant IRX-2 increased TILs in a head/neck squamous cell carcinoma trial. We conducted a phase Ib trial to evaluate the feasibility/activity of IRX-2 in ESBC. Methods: Beginning 21 days prior to surgical resection, enrolled operable patients with stage I-III ESBC received the pre-operative IRX-2 regimen consisting of a single low dose of cyclophosphamide (300 mg/m2 to facilitate T-regulatory cell depletion), followed by 10 days of subcutaneous peri-areolar injections of IRX-2 into the affected breast (1 mL × 2 at tumor axis and at 90°). Endpoints were feasibility (primary), sTIL count (secondary), and immune monitoring by flow cytometry and immune transcriptome analysis (Nanostring PanCancer Immune Panel). Results: As of October 2017, 12 patients are enrolled and evaluable. All patients received all planned injections with no treatment-related surgical delays, complications, or grade III/IV toxicities. Treatment was associated with a mean 52% relative increase in sTILs (range –25% to +166%, p = 0.02). RNA expression profiling revealed the greatest increases in Th1 cell signature (mean +28.5%, range -5.3% to +283%), but also increases in CD8+, NK, and DC signatures. PDL1 RNA expression increased in 10/12 patients (mean +131.5%, range –83% to +1112%). In blood, increases in T-cell activation markers (ICOS, HLADR, and CD38) and T-reg depletion were observed at 1-month follow-up. Conclusions: Peri-lymphatic IRX-2 was well tolerated with preliminary evidence of sTIL recruitment, PDL1 upregulation, and peripheral lymphocyte activation. Study enrollment is ongoing, including patients for a pre-neoadjuvant-chemotherapy triple-negative ESBC cohort. Clinical trial information: NCT02950259.