Because PD-1 therapies only benefit approximately 1 in 5 patients with NSCLC, there is a great need to improve immunotherapy for this disease. A distinct form of immunotherapy, IL-2, can yield complete responses in melanoma and renal cell carcinoma. Use of IL-2 is limited due to common life-threatening toxicity. An alternative to IL-2 is IL-15/IL-15R? complexes. ALT-803 is a clinical grade IL-15/IL-15R? complex and powerful super-agonist for IL-15 responsive CD8+ lymphocytes and natural killer (NK) cells with dramatically improved safety compared with IL-2. Preclinical studies combining ALT-803 with anti-PD-1 mAb demonstrate remarkable anti-tumor efficacy associated with expansion of both CD8+ T cells and NK cells, and the production of inflammatory cytokines such as IL-6 and IFN?. We have moved this therapy into the clinic with an investigator- initiated, first-in-human, phase Ib/II trial testing the clinical hypothesis that adding IL-15/IL-15R? complexes (ALT- 803) to anti-PD1 mAb (nivolumab) is safe and efficacious in NSCLC (NCT02523469). To date 11 patients have been treated with three highly active dose levels (6, 10, 15 mcg/kg SC, 15 being the highest planned dose) with zero observed dose limiting toxicities (DLTs) and excellent activation of CD8+ T cells and NK cells and increases in serum IL-6 and IFN?. The goal of this application is to determine the mechanistic basis and predictors of response for this promising combinatorial approach using our unique bank of trial-derived samples and a powerful preclinical lung tumor model. We hypothesize that the addition of IL-15/IL-15R? complexes to anti-PD- 1 mAb augments anti-tumor efficacy through enhanced expansion and functional activation of tumor-reactive CD8+ lymphocytes and NK cells and that the induction of inflammatory cytokines such as IL-6 and IFN? will be associated with anti-tumor efficacy. We further hypothesize enhanced anti-tumor efficacy will depend on effector lymphocytes (CD8+ and NK but not CD4+) and correlate with cytokines (IL-6 and IFN?).
Specific Aim 1 : Using state-of-art mass cytometry we will perform the high-dimension characterization of both NK and CD8+ T cell compartments from longitudinal PBMC samples of up to 116 patients. We will perform TCR sequencing on expanded T cells to determine if they originate from tumor. We will also perform 65-plex serum cytokine/chemokine analysis of longitudinally acquired samples to identify novel serum biomarkers. We will associate changes in lymphocyte and serum cytokines/chemokines parameters with clinical response.
Specific Aim 2 : We will use our Lewis lung carcinoma (LLC) mouse model to inform our future clinical efforts with the combination of anti-PD-1 mAb and IL-15/sIL-15R? complexes. First, we will identify cellular and molecular markers that correlate with treatment outcome using longitudinal analysis of responding and non-responding mice. Second we will validate critical pathways using antibody-mediated depletion of lymphocyte subsets or cytokines. Finally, we will evaluate the effects of alternate dosing and schedule on key effector populations, and also integrate anti-CTLA-4 mAb therapy into our treatment.
The grant application requests the funds needed to perform a sophisticated immune analysis of the patient blood and tumor samples of clinical trial specimens with the goal of understanding relevant mechanisms and identifying biomarkers that may predict patients that are likely to respond to therapy. Importantly, funding of this grant application would provide the investigators with protected time to analyze an incredible wealth of data that is expected to be generated.
