ATALANTE-1: anti-cancer vaccination after IO failure

OSE-2101 is an anti-cancer vaccine with modified neoepitopes restricted to HLA-A2+ targeting the tumor-associated antigens CEA, p53, HER2, MAGE-2 and MAGE-3 that are frequently expressed in lung cancer [1]. HLA-A2 is assessed in the serum and is positive in approximately half of patients. The randomized, phase III ATALANTE-1 trial tested OSE-2101 in patients with HLA-A2–positive, advanced or metastatic NSCLC who had experienced failure to combined or sequential platinum-based chemotherapy and immunotherapy. Immunotherapy had been administered in the most recent line and had failed due to primary or secondary resistance. Six subcutaneous injections of OSE-2101 were given Q3W followed by Q8W injections for up to year 1 and then 12-weekly injections until progression, while treatment in the control arm consisted of single-agent docetaxel or pemetrexed Q3W until progression. OSE-2101 gave rise to an OS benefit in 103 patients, with 1-year rates of 46 % vs. 36 % (HR, 0.71) [2]. However, due to the COVID-19 pandemic, the study was stopped in April 2020, and a population of interest was identified for further analyses. This comprised 118 patients who had secondary resistance to immunotherapy after sequential chemo-immunotherapy. At ESMO 2021, Besse et al. presented the results of the final primary analysis performed in this group [3].

Indeed, the cancer vaccine gave rise to statistical OS improvement with a meaningful median survival gain of 3.6 months (11.1 vs. 7.5 months; HR, 0.59; p = 0.017). Moreover, OSE-2101 treatment resulted in significantly longer post-progression survival (7.7 vs. 4.6 months; HR, 0.46; p = 0.004). The disease control rates at 6 months were similar across the two arms (25 % vs. 24 %; p = 0.87), which also applied to median PFS (2.7 vs. 3.2 months; p = 0.40). OSE-2101 was well tolerated, with a lower rate of treatment-related grade 3-5 AEs (11 % vs. 35 %). Administration site reactions occurred most commonly in the experimental arm (all grades, 39 %). Cytokine release syndrome was observed in 8 %, including one grade 3 event (1 %). The vaccine induced significant improvements in time to worsening to ECOG performance status ≥ 2 (8.6 vs. 3.3 months; HR, 0.45; p = 0.0005) and quality of life according to the EORTC QLQ-C30 questionnaire (p = 0.04). In their conclusion, the authors noted that OSE-2101 demonstrated a favorable benefit-risk ratio vs. chemotherapy in a setting that is characterized by a lack of therapeutic alternatives.


  1. Beebe M et al., Formulation and characterization of a ten-peptide single-vial vaccine, EP-2101, designed to induce cytotoxic T-lymphocyte responses for cancer immunotherapy. Hum Vaccin 2008; 4(3): 210-218
  2. Giaconne G et al., Activity of OSE-2101 in HLA-A2+ non-small cell lung cancer patients after failure to immune checkpoint inhibitors: Step 1 results of phase III ATALANTE-1 randomised trial. ESMO 2020 1260M0
  3. Besse B et al., Activity of OSE-2101 in HLA-A2+ non-small cell lung cancer patients after failure to immune checkpoint inhibitors: final results of phase 3 Atalante-1 randomised trial. ESMO 2021, LBA47

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