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Evaluation of the biological activities of the IL-15 superagonist complex, ALT-803, following intravenous versus subcutaneous administration in murine models.

ABSTRACT: ALT-803 is a fusion protein complex consisting of an interleukin (IL)-15 superagonist and a dimeric IL-15 receptor alpha sushi domain IgG1 Fc fusion protein. When administered to mice, ALT-803 is capable of inducing natural killer (NK) and CD8+ T cell proliferation and activation, and effectively promoting potent anti-tumor responses. Currently, ALT-803 is in clinical trials for treatment of various solid tumors and hematological malignancies. In the initial phase of these clinical studies, intravenous (iv) injection was used according to the route used in pre-clinical efficacy studies. In order to evaluate the possible advantage of subcutaneous (sc) injection versus iv injection, this study compared the biological activity of the two treatment regimens of ALT-803 in pre-clinical in vivo models. The pharmacokinetics, immune stimulation, and anti-tumor efficacy of iv and sc injection routes of ALT-803 in C57BL/6 mice were compared. The half-life of ALT-803 was 7.5?h for iv versus 7.7?h for sc with the maximal detected serum concentration of ALT-803 to be 3926?ng/ml at 0.5 h time-point following iv injection versus 495?ng/ml at 16?h post sc injection. Biodistribution studies indicated that sc ALT-803, similarly to iv ALT-803 as previously reported, has a greater tissue distribution and longer residence time in lymphoid tissues compared to recombinant IL-15. Notably, ALT-803 when administered either iv or sc induced comparable proliferation and activation of CD8+ T and NK cells and resulted in similar reductions of tumor burden. A toxicity study of mice receiving multiple injections of ALT-803 for 4?weeks by iv or sc routes revealed equivalent immune-related changes. The gradual absorbance into the blood stream and lower maximal blood levels of ALT-803 in sc-injected mice, along with similar anti-tumor efficacy support the administration of ALT-803 by sc injection in patients with various malignancies and infectious diseases.

SUBMITTER: Liu B

PROVIDER: S-EPMC5916319 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Project description:BackgroundWe set out to determine if the administration of subcutaneous (SQ) ALT-803 was non-inferior to standard intravesical BCG treatment in a carcinogen induced mouse (C57BL/6J) bladder cancer model.MethodsUsing this well-established carcinogen induced mouse model, we studied the effects of various dosing schemas of ALT-803 (SQ alone, SQ with intravesical BCG, intravesical alone, intravesical with intravesical BCG) compared to intravesical BCG alone (positive control) and PBS (negative control). The non-inferiority margin for the difference in bladder weight, as a surrogate for tumor mass, was defined as 7%.ResultsAll treatment groups (i.e., ALT-803 SQ alone, ALT-803 SQ with intravesical BCG, ALT-803 intravesical alone, ALT-803 intravesical with intravesical BCG and intravesical BCG alone) demonstrated a significant reduction in tumor burden as evident by bladder weights and H&E stain (p?<?0.005). Non-inferiority tests between the intravesical BCG alone group and the additional treatment groups showed that SQ ALT-803 alone (p?=?0.04) and BCG plus SQ ALT-803 (p?=?0.009) were non-inferior to intravesical BCG alone. In this model, we did not see an appreciable infiltration of CD4+ T, CD8+ T or CD161/KLRB1+ natural killer (NK) cells in the bladder/tumor. When assessing peripheral blood mononuclear cells, SQ ALT-803 alone resulted in a robust induction of CD8+ T cells (p?<?0.01), NKG2D+ NK cells (p?<?0.005) and CD3+/NKG2D+ NKT cells (p?<?0.005) compared to other groups, while in splenic tissue, SQ ALT-803 alone resulted in a robust induction of CD3+/NKG2D+ NKT cells (p?<?0.005) compared to other groups.ConclusionSubcutaneous ALT-803 treatment alone or in combination with intravesical BCG was well tolerated and was not inferior to intravesical BCG alone. CD8+ T, NKG2D+ NK and CD3+/NKG2D+ NKT cell induction along with induction of key cytokines remain steadfast mechanisms behind ALT-803. The enhanced therapeutic index seen with BCG and ALT-803, administered SQ or intravesically, provides a powerful justification for the further development of these regimens.

Project description:BACKGROUND:Immunotherapy with PD-1 or PD-L1 blockade fails to induce a response in about 80% of patients with unselected non-small cell lung cancer (NSCLC), and many of those who do initially respond then develop resistance to treatment. Agonists that target the shared interleukin-2 (IL-2) and IL-15R?? pathway have induced complete and durable responses in some cancers, but no studies have been done to assess the safety or efficacy of these agonists in combination with anti-PD-1 immunotherapy. We aimed to define the safety, tolerability, and activity of this drug combination in patients with NSCLC. METHODS:In this non-randomised, open-label, phase 1b trial, we enrolled patients (aged ?18 years) with previously treated histologically or cytologically confirmed stage IIIB or IV NSCLC from three academic hospitals in the USA. Key eligibility criteria included measurable disease, eligibility to receive anti-PD-1 immunotherapy, and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients received the anti-PD-1 monoclonal antibody nivolumab intravenously at 3 mg/kg (then 240 mg when US Food and Drug Administration [FDA]-approved dosing changed) every 14 days (either as new treatment or continued treatment at the time of disease progression) and the IL-15 superagonist ALT-803 subcutaneously once per week on weeks 1-5 of four 6-week cycles for 6 months. ALT-803 was administered at one of four escalating dose concentrations: 6, 10, 15, or 20 ?g/kg. The primary endpoint was to define safety and tolerability and to establish a recommended phase 2 dose of ALT-803 in combination with nivolumab. Analyses were per-protocol and included any patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, number NCT02523469; phase 2 enrolment of patients is ongoing. FINDINGS:Between Jan 18, 2016, and June 28, 2017, 23 patients were enrolled and 21 were treated at four dose levels of ALT-803 in combination with nivolumab. Two patients did not receive treatment because of the development of inter-current illness during enrolment, one patient due to leucopenia and one patient due to pulmonary dysfunction. No dose-limiting toxicities were recorded and the maximum tolerated dose was not reached. The most common adverse events were injection-site reactions (in 19 [90%] of 21 patients) and flu-like symptoms (15 [71%]). The most common grade 3 adverse events, occurring in two patients each, were lymphocytopenia and fatigue. A grade 3 myocardial infarction occurred in one patient. No grade 4 or 5 adverse events were recorded. The recommended phase 2 dose of ALT-803 is 20 ?g/kg given once per week subcutaneously in combination with 240 mg intravenous nivolumab every 2 weeks. INTERPRETATION:ALT-803 in combination with nivolumab can be safely administered in an outpatient setting. The promising clinical activity observed with the addition of ALT-803 to the regimen of patients with PD-1 monoclonal antibody relapsed and refractory disease shows evidence of anti-tumour activity for a new class of agents in NSCLC. FUNDING:Altor BioScience (a NantWorks company), National Institutes of Health, and Medical University of South Carolina Hollings Cancer Center.

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Evaluation of the biological activities of the IL-15 superagonist complex, ALT-803, following intravenous versus subcutaneous administration in murine models.

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