This study explored the combination of fibroblast activation protein (FAP) IL2 variant (FAP-IL2v), a novel immune-cytokine, with pembrolizumab in patients with advanced and/or metastatic melanoma.
This open-label, multicenter, phase Ib clinical study (NCT03875079) evaluated the safety, tolerability, pharmacodynamics, pharmacokinetics, and antitumor activity of FAP-IL2v (simlukafusp alfa, RO6874281) in combination with pembrolizumab. Patients with advanced and/or metastatic melanoma were either checkpoint inhibitor (CPI)-naïve or CPI-experienced. Patients received 10 mg FAP-IL2v either continuously once every 3 weeks (Q3W) or in an induction/maintenance setting consisting of a 3-week induction phase with weekly (QW) dosing followed by continuous Q3W dosing. Pembrolizumab was dosed Q3W at 200 mg.
Eighty-three patients were treated: 16 patients in two safety run-in cohorts and 67 patients in two extension cohorts; 75 (90.4%) patients were CPI-experienced. The pharmacokinetics of FAP-IL2v in combination with pembrolizumab was similar to that after administration as monotherapy. Consistent with the proposed mode of action, FAP-IL2v preferentially expanded NK and CD8 T cells. The most common FAP-IL2v-related grade 3/4 adverse events were lymphopenia (23%), elevated γ-glutamyltransferase (8%), elevated alanine aminotransferase (6%), and infusion-related reaction (6%). A response was observed in 5 of 75 (6.7%) CPI-experienced patients (all partial responses) and 2 of 8 CPI-naïve patients (one complete response and one partial response). The median progression-free survival was 3.1 months.
The safety profile of FAP-IL2v in combination with pembrolizumab was manageable and consistent with the known safety profile. However, further exploration of FAP-IL2v and pembrolizumab was precluded in patients with melanoma with prior CPI due to the lack of clinical activity.
In this phase Ib study, the combination of FAP-IL2v, an immune-cytokine developed to overcome the limitations of wild-type IL2, with the CPI pembrolizumab did not show meaningful antitumor activity in patients who had progressed on prior CPI therapy, suggesting that FAP-IL2v alone cannot overcome CPI resistance or unresponsiveness.
©2025 The Authors; Published by the American Association for Cancer Research.

This phase Ib trial evaluated fibroblast activation protein-α-targeted IL2 variant (FAP-IL2v), a novel immunocytokine engineered to minimize CD25-mediated toxicities, in combination with cetuximab, in patients with recurrent, unresectable, or metastatic head and neck squamous cell carcinoma (HNSCC).
Patients received FAP-IL2v either on a continuous weekly (QW) schedule or QW for 4 weeks and then every 2 weeks (Q2W). Cetuximab was dosed at QW or Q2W schedules. The primary objectives were to evaluate the safety and tolerability, maximum tolerated dose, pharmacokinetics, and clinical activity for the combination of FAP-IL2v with cetuximab. Exploratory objectives included pharmacodynamic analyses.
A total of 58 patients were enrolled, 19 patients into the dose-escalation part, and 39 patients into the expansion part. The maximum tolerated dose of FAP-IL2v was defined as 10 mg (QW/Q2W) in combination with cetuximab (500 mg/m2, Q2W), which was further tested in the expansion part. The most common FAP-IL2v-related adverse events with a grade 3 or 4 severity were hypophosphatemia (19%), lymphopenia (16%), and infusion-related reaction (14%). The pharmacokinetics of FAP-IL2v in combination with cetuximab was similar to that after administration as monotherapy. Consistent with the proposed mode of action, FAP-IL2v preferentially expanded intratumoral NK and CD8 T cells. Four patients achieved a partial response, and the objective response rate was 7% (95% confidence interval, 3.2-14.7).
The safety profile of FAP-IL2v in combination with cetuximab was acceptable, and pharmacodynamic markers support the proposed mode of action of this combination, but the overall low antitumor activity does not warrant further clinical exploration in HNSCC. [Part C of Study BP29842 (NCT02627274).].
©2024 The Authors; Published by the American Association for Cancer Research.

Cellular energy metabolism significantly contributes to immune cell function. To further advance immunometabolic research, novel methods to study the metabolism of immune cells in complex samples are required. Here, we introduce CENCAT (cellular energetics through noncanonical amino acid tagging). This technique utilizes click labeling of alkyne-bearing noncanonical amino acids to measure protein synthesis inhibition as a proxy for metabolic activity. CENCAT successfully reproduced known metabolic signatures of lipopolysaccharide (LPS)/interferon (IFN)γ and interleukin (IL)-4 activation in human primary macrophages. Application of CENCAT in peripheral blood mononuclear cells revealed diverse metabolic rewiring upon stimulation with different activators. Finally, CENCAT was used to analyze the cellular metabolism of murine tissue-resident immune cells from various organs. Tissue-specific clustering was observed based on metabolic profiles, likely driven by microenvironmental priming. In conclusion, CENCAT offers valuable insights into immune cell metabolic responses, presenting a powerful platform for studying cellular metabolism in complex samples and tissues in both humans and mice.
Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.

In human sepsis, myelocytosis and concomitant lymphopenia complicate the study of peripheral blood natural killer (NK) cells. Here, we present a protocol for isolating NK cells from peripheral blood of septic patients using magnetic cell separation. We describe steps for the depletion of non-NK cells and NK cell enrichment. We then detail procedures for comparing the results from this protocol to results obtained through the isolation procedures using two commercially available kits for NK cell isolation. For complete details on the use and execution of this protocol, please refer to Coulibaly et al.1.
Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.

FMS-related tyrosine kinase 3 ligand (FLT3L), encoded by FLT3LG, is a hematopoietic factor essential for the development of natural killer (NK) cells, B cells, and dendritic cells (DCs) in mice. We describe three humans homozygous for a loss-of-function FLT3LG variant with a history of various recurrent infections, including severe cutaneous warts. The patients' bone marrow (BM) was hypoplastic, with low levels of hematopoietic progenitors, particularly myeloid and B cell precursors. Counts of B cells, monocytes, and DCs were low in the patients' blood, whereas the other blood subsets, including NK cells, were affected only moderately, if at all. The patients had normal counts of Langerhans cells (LCs) and dermal macrophages in the skin but lacked dermal DCs. Thus, FLT3L is required for B cell and DC development in mice and humans. However, unlike its murine counterpart, human FLT3L is required for the development of monocytes but not NK cells.
Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.