Johan Vansteenkiste’s research while affiliated with KU Leuven and other places

Background PDC*lung01 (IMP) is a therapeutic cancer vaccine based on an irradiated plasmacytoid dendritic cell line loaded with HLA-A*02:01-restricted peptides (NY-ESO-1, MAGE-A3, MAGE-A4, Multi-MAGE-A, MUC1, Survivin and Melan-A), able to prime and expand peptide-specific CD8+ T cells in vitro and in vivo, and is synergistic with anti-PD-1. Methods In this phase I/II study, HLA-A*02 positive NSCLC pts were enrolled in 4 cohorts: resected stage II/IIIA in adjuvant setting treated with low dose (A1) or high dose (A2) of IMP following SOC; or untreated stage IV NSCLC with measurable disease, PD-L1≥50% and no targetable driver mutation, treated with low dose (B1) or high dose (B2) of IMP in combination to pembrolizumab 200mg q3w, continuously. IMP was simultaneously administered by SC and IV route weekly for 6 consecutive doses. Objective response rate (ORR) and progression-free survival (PFS) were assessed in cohort B2. We report herein preliminary efficacy results of the first 21 pts analysed when the 19th evaluable patient reached the 9-months PFS and the safety of 38 pts. Results Out of 21, 19 pts receiving at least 5 doses of IMP and having 1 post-baseline radiological evaluation were evaluated. The median follow-up was 12.5 months. The best objective response (BOR) included 12 PR (63.2%) and 7 SD (36.8%) with ORR of 63.2% (80% CI 45.9% - 78.2%) and a disease control rate (DCR) of 94.7%. The 9mPFS according to the Kaplan-Meier estimate was 52.1% (80% CI 36.5% - 65.56%). The mPFS was 10.9 months. The median duration of response was 9.49 months. An antigen-specific CD8+ T-cell response was induced against the lung antigens of the IMP in 68.4% of pts. Immune responses with remarkable expanded anti-tumor CD8+ T-cells were observed both in PR and SD. More immune response results will be available in the final analysis of the 45 pts of cohort B2. Treatment-related AEs (TRAEs) were mostly Grade 1-2. Only 1 severe TRAE occurred, a Grade 4 allergic infusion-related reaction, leading to IMP discontinuation. Thirteen pts experienced a serious AE, of which 3 were considered causally related to the IMP. Conclusions The BOR, ORR, DCR, PFS, duration of response and safety of PDC*lung01 in combination with anti-PD-1 showed encouraging signals suggesting that this combination may provide a clinical meaningful tumour response in stage IV NSCLC population with a mild safety profile. Interestingly, the immune response observed confirms the mechanism of action of the IMP in relation to clinical activity. Citation Format: Willemijn Theelen, Maurice Perol, Kristof Cuppens, Ingel Demedts, Frank Borm, Bonne Biesma, Els Wauters, Benoit Colinet, Eva-Lotte Buchmeier, Friederike Althoff, Elvire Pons-Tostivint, Charlotte Van de Kerkhove, Denis Moro-Sibilot, Anne Sibille, Sofie Derijcke, Marcin Skrzypski, Joel Plumas, Beatrice De Vos, Channa Debruyne, Frederique Cantero, Stefanie Adriaenssens, Florence Renard, Johan Vansteenkiste. Preliminary clinical results of a therapeutic cancer vaccine PDC*lung01 in combination with anti-PD-1 in patients (pts) with stage IV NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT021.

We have developed an innovative cancer vaccine for the treatment of advanced NSCLC patients in combination with checkpoint inhibitors. This PDC*lung01 product based on an irradiated plasmacytoid dendritic cell line loaded with HLA-A*02:01 restricted peptides (NY-ESO-1, MAGE-A3, MAGE-A4, Multi-MAGE-A, MUC1, Survivin and Melan-A) is able to prime and expand peptide-specific CD8+ T cells in vitro and in vivo, and is synergistic with anti-Programmed Death (PD)-1 (Plumas et al, 2022; Hannani et al, 2023, NCT03970746). In study PDC-LUNG-101 with EudraCT number 2018-002382-19, PDC*lung01 is injected intravenously and subcutaneously for 6 times at two dose levels, 14 million, or 140 million cells in stage II/IIIA (cohort A1 & A2, monotherapy) or stage IV with TPS≥50% (cohort B1 & B2; in combination with pembrolizumab) patients. We report here the analysis of immune response of 3 cohorts (A1, A2, B1) of patients and the first 19 patients out of 42 (cohort B2) treated with high dose of PDC*lung01 in combination with Pembrolizumab at baseline and 3 timepoints post injection. Several circulating immune parameters have been evaluated at different times before and after vaccination using different assays we have developed: leukocyte count and determination of circulation peptide specific CD8+ T cells by flow cytometry using multimer tools without prior in vitro culture. The assay made on purified CD8+ T-cells allowed us to define a limit of quantification (LOQ) to accurately assess the fold changes of the cell expansion. In addition, tumor microenvironment (TME) was analyzed by multiplex fluorescence immunochemistry. The data of 42 patients for who an immune response has been evaluated (cohorts A and B) will be presented. No major changes in circulating main lymphocyte frequencies (B cells, NK cells, CD4+, CD8+, or Treg T cells) were observed during treatment. In addition, no major cell activation (CD25+, CD54, or DR+) was noted. In contrast, in a significant number of patients, PDC*lung01 induced circulating peptide-specific CD8+ T cell expansion in all 4 cohorts at different levels and time points against at least one out of seven peptides used. The percentages of patients for who an expansion of antigen-specific T-cell were observed were 50%, 64%, 66.7% and 68.4% in A1, A2, B1 and B2 cohorts respectively. The intensity of the immune response was proportional to the dose of PDC*lung01 and to the combination with pembrolizumab. When possible, total and peptide-specific CD8+ T cells were sorted for analysis of TCR repertoire, illustrating the modelling and dynamics of the immune response. The TME features will also be illustrated. To conclude, treatment with PDC*lung01 induces an anti-tumor immune response in a significant number of patients which appears to be enhanced by the combination with pembrolizumab. Citation Format: Joel Plumas, Anne Sibille, Ingel Demedts, Elvire Pons-Tostivint, Charlotte Van de Kerkhove, Sofie Derijcke, Willemijn Theelen, Bonne Biesma, Frank Borm, Els Wauters, Mike Collodoro, Kays Al Badawy, Camille Duchayne, Channa Debruyne, Beatrice Devos, Benoit Colinet, Denis Moro-Sibilot, Maurice Perol, Eva-Lotte Buchmeier, Marcin Skrzypski, Kristof Cuppens, Johan Vansteenkiste. PDC*lung01: An innovative therapeutic cancer vaccine induces specific immune responses in combination with anti- PD-1 treatment in patients with non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1182.

Introduction In the placebo-controlled, phase 3 PACIFIC trial, durvalumab significantly prolonged progression-free survival (PFS) (p < 0.0001) and overall survival (OS) (p = 0.00251) in patients with unresectable stage III NSCLC and no progression after platinum-based concurrent chemoradiotherapy (cCRT). Pneumonitis or radiation pneumonitis (PRP) was common in both arms. We report exploratory analyses evaluating the association of symptomatic (grade ≥2) PRP (G2+PRP) with baseline factors and clinical outcomes. Methods Patients with WHO performance status of 0 or 1 were randomized (2:1) to 12 months of durvalumab or placebo, 1 to 42 days after cCRT. Associations between baseline factors and on-study G2+PRP in durvalumab-treated patients were investigated using univariate and multivariate logistic regression. PFS and OS were analyzed using Cox proportional hazards models adjusted for time-dependent G2+PRP plus covariates for randomization stratification factors without and with additional baseline factors. Results On-study G2+PRP occurred in 94 of 475 (19.8%) and 33 of 234 patients (14.1%) on durvalumab and placebo, respectively (median follow-up, 25.2 mo); grade greater than or equal to 3 PRP was uncommon (4.6% and 4.7%, respectively). Time to onset and resolution of G2+PRP was similar with durvalumab and placebo. Univariate and multivariate analyses identified patients treated in Asia, those with stage IIIA disease, those with performance status of 1, and those who had not received induction chemotherapy as having a higher risk of G2+PRP. PFS and OS benefit favoring durvalumab versus placebo was maintained regardless of time-dependent G2+PRP. Conclusions Factors associated with higher risk of G2+PRP with durvalumab after cCRT were identified. Clinical benefit was maintained regardless of on-study G2+PRP, suggesting the risk of this event should not deter the use of durvalumab in eligible patients with unresectable stage III NSCLC.

8520 Background: In the randomized, triple-blind, phase 3 PEARLS/KEYNOTE-091 study (NCT02504372), at the second interim analysis, pembrolizumab (pembro) significantly prolonged DFS vs placebo (pbo) in the overall population of patients (pts) with completely resected stage IB–IIIA NSCLC per AJCC v7 who may or may not have received adjuvant chemotherapy (chemo; up to 4 cycles) as recommended per local guidelines (n = 1177; HR, 0.76 [95% CI, 0.63–0.91]; P = 0.0014). Here we present outcomes for those pts who received 1–4 cycles of prior adjuvant chemo, per protocol. Methods: Eligible adults had pathologically confirmed, completely resected stage IB (T ≥4 cm), II, or IIIA NSCLC (AJCC v7) of any PD-L1 expression, ECOG performance status of 0 or 1, and had not received neoadjuvant radiotherapy or chemo. Pts were randomized 1:1 to pembro 200 mg or pbo Q3W for 18 doses (~1 year); receipt of adjuvant chemo (yes vs no) was one of the stratification factors. Dual primary endpoints were DFS in the ITT and PD-L1 TPS ≥50% populations. No alpha was assigned to this subgroup analysis of pts who received adjuvant chemo for 1–4 cycles per local guidelines. Results: Of 1177 pts in the ITT population, 1010 (85.8%) received adjuvant chemo and were included in this analysis (pembro, n = 506; pbo, n = 504). Pts received a median of 17 and 18 study doses, respectively. As of data cutoff (Sep 20, 2021), 52.6% in the pembro arm vs 64.9% in the pbo arm had completed treatment. Median time from randomization to data cutoff was 37.4 mo. Median (95% CI) DFS was 58.7 mo (39.2 mo–not reached [NR]) in the pembro arm vs 34.9 mo (28.6 mo–NR) in the pbo arm (HR, 0.73 [95% CI, 0.60–0.89]). Estimated 18-mo DFS rates were 73.8% and 63.1%, respectively. In pts with PD-L1 TPS ≥50% (pembro, n = 143; pbo, n = 141), median DFS was NR in both treatment arms (HR, 0.80 [95% CI, 0.54–1.20]). Grade 3–5 adverse events (AEs) occurred in 170 pts (34.3%) in the pembro arm and 128 (25.7%) in the pbo arm (grade 5, 2.2% vs 1.0%). Immune-mediated AEs and infusion reactions occurred in 195 pts (39.3%) in the pembro arm and 69 (13.8%) in the pbo arm. Conclusions: Consistent with the ITT population, pembro substantially improved DFS vs pbo in the subgroup of pts with stage IB (T2a ≥4 cm), II, or IIIA NSCLC who received adjuvant platinum-based chemo following complete resection. Based on these results, pembro was approved for adjuvant treatment in this pt population by the US FDA. Clinical trial information: NCT02504372 .