POLB 001, a p38 MAPK inhibitor, decreases local and systemic inflammatory responses following in vivo LPS administration in healthy volunteers: a randomised, double-blind, placebo-controlled study

Abstract

Background and aim: POLB 001 is an oral p38 mitogen-activated protein kinase (MAPK) inhibitor in development for the prevention of cancer immunotherapy-induced cytokine release syndrome (CRS). It has previously been shown to be well tolerated and capable of decreasing ex vivo lipopolysaccharide (LPS)-induced tumour necrosis factor (TNF) secretion in a phase 1 first-in-human trial. This study aimed to evaluate the anti-inflammatory effects of POLB 001 following in vivo LPS administration in healthy volunteers.

Methods: Participants received POLB 001 at doses of 30, 70, or 150 mg, or placebo, twice daily for seven consecutive days and were challenged locally with intradermal (ID) LPS on day 4 and systemically with intravenous (IV) LPS on day 6. Following ID LPS administration, skin perfusion and erythema were measured, and skin suction blisters were created to collect blister fluid containing infiltrating immune cells and extracellular fluid. Following IV LPS administration, circulating cytokine levels, leukocyte counts, leukocyte p38 MAPK phosphorylation levels, and vital signs were measured.

Results: POLB 001 was well tolerated. It reduced the ID LPS-driven immune cell attraction and cytokine responses measured in blister fluid. The suppression of immune cell recruitment was most pronounced in neutrophils (72.4%-81.5%, p = 0.0091), classical monocytes (68.4%-73.6%, p = 0.0036), CD3⁺ T cells (56.4%-65.9%, p = 0.0047), and myeloid dendritic cells (59%-64.4%, p = 0.0174). The suppression of cytokine responses was most pronounced for TNF (35.3%-65.1%, p = 0.0099). Overall, POLB 001 did not substantially modulate the intradermal LPS-driven increase in local erythema and perfusion. POLB 001 significantly reduced the IV LPS-driven increase in interleukin (IL)-6, IL-8, and TNF (37.7%-80.7%, all p < 0.0003), p38 MAPK phosphorylation levels in target cells (16.7%-60.9%, all p < 0.0001), and heart rate increase (4-9.3 bpm, p < 0.0001).

Conclusion: POLB 001 was safe and well-tolerated. Pharmacodynamic findings confirm that POLB 001 inhibits LPS-induced local and systemic inflammation in vivo through inhibition of p38 MAPK.

Clinical trial registration: https://onderzoekmetmensen.nl/en/trial/51741, identifier NL81214.056.22.

Keywords: Cytokine release syndrome (CRS); LPS; in vivo; inflammation; p38 MAPK.

Figure 1

Overview of the study design. POLB 001 or a matching placebo was administered twice daily for seven consecutive days. On day 4, participants received four intradermal injections of LPS. The local response was evaluated at specified timepoints by using different imaging techniques and skin blister fluid analysis. On day 6, participants received a single dose of intravenous LPS, with pre- and posthydration. Endpoints included different blood assessments and vital signs. The asterisk indicates PK on day 1 only for the highest dose group. PK, pharmacokinetics; LPS, lipopolysaccharide; MSD, Meso Scale Discovery; CRP, C-reactive protein. Created withBiorender.com.

Figure 2

Quantification of the inflammatory skin response following the intradermal LPS challenge by (A) multispectral imaging (erythema) and (B) laser speckle contrast imaging (LSCI; perfusion). In (A), POLB 001–30 mg vs. placebo showed p < 0.05, whereas other contrasts showed p > 0.05. In (B), POLB 001 vs. placebo, all p > 0.05. Data are expressed as means with SD. AU, arbitrary units; ID, intradermal; LPS, lipopolysaccharide.

Figure 3

Overview of skin blister fluid analysis by flow cytometry following intradermal LPS administration: (A) CD3⁺ T cells, (B) CD4⁺ T cells, (C) CD8⁺ T cells, (D) mDCs, (E) classical monocytes, and (F) neutrophils. In (A, B), POLB 001 vs. placebo, all p < 0.01. In (C), POLB at 30 mg vs. placebo showed p > 0.05, whereas POLB 001 at 70 and 150 mg vs. placebo showed p < 0.01. In (D), POLB 001 vs. placebo, all p < 0.05. In (E), POLB 001 vs. placebo, all p < 0.01. In (F), POLB 001 vs. placebo, all p < 0.05. Data are expressed as means with SD. ID, intradermal; LPS, lipopolysaccharide; mDCs, myeloid dendritic cells; SD, standard deviation.

Figure 4

Overview of cytokine responses in skin blister fluid following intradermal LPS administration: (A) IL-1β response, (B) TNF response, (C) IL-8 response, and (D) IL-6 response. In (A), POLB 150 mg vs. placebo showed p < 0.02, whereas other contrasts showed p > 0.05. In (B), POLB 150 mg vs. placebo showed p < 0.02, whereas other contrasts showed p > 0.05. In (C), POLB 001 vs. placebo, all p > 0.05. In (D), due to too many values above the ULOQ, the requirement for analysis was not met. Data are expressed as means with SD. ID, intradermal; LPS, lipopolysaccharide; TNF, tumour necrosis factor; IL, interleukin.

Figure 5

Overview of p38 MAPK phosphorylation in CD14⁺ monocytes expressed as (A) MFI and (B) percentage. In (A), POLB 001 vs. placebo, all p < 0.02. In (B), POLB 001 vs. placebo, all p < 0.05. Data are expressed as means with SD. IV, intravenous; LPS, lipopolysaccharide; MAPK, mitogen-activated protein kinase; MFI, mean fluorescence intensity.

Figure 6

Overview of vital sign measurements during the IV LPS challenge: (A) heart rate, (B) temperature, (C) systolic blood pressure, and (D) diastolic blood pressure. In (A), POLB 001 vs. placebo, all p < 0.05. In (B–D), POLB 001 vs. placebo, all p > 0.05. Data are expressed as means with SD. IV, intravenous; LPS, lipopolysaccharide; bpm, beats per minute; °C, degrees Celsius.

Figure 7

Overview of the cytokine and CRP response in plasma during the IV LPS challenge: (A) IL-6, (B) IL-8, (C) TNF, (D) IL-10, (E) IL-1β, and (F) CRP. In (A–C), POLB 001 vs. placebo, all p < 0.05. In (D), POLB 001 at 30 mg vs. placebo showed p > 0.05, whereas POLB 001 at 70 and 150 mg vs. placebo showed p < 0.001. In (E), due to levels below the LLOQ, the requirements for analysis were not met. In (F), POLB 001–30 at mg vs. placebo showed p > 0.05, whereas POLB 001 at 70 and 150 mg vs. placebo showed p < 0.05. Data are expressed as means with SD. IV, intravenous; LPS, lipopolysaccharide; TNF, tumour necrosis factor; IL, interleukin; CRP, C-reactive protein.