CHIMERA: A Phase II Study of Neoadjuvant Pembrolizumab in Combination With Cisplatin or Carboplatin and Pemetrexed Followed by Surgery and Adjuvant Pembrolizumab in Resectable Pleural Mesothelioma

Clinical Lung Cancer 2026 July [Link]

Giulia Pasello, Daniela Scattolin, Eleonora Faccioli, Paolo Andrea Zucali, Giuseppe Marulli, Federica Grosso, Giovanni Luca Ceresoli, Marcello Tiseo, Alessandra Bearz, Fabiana Letizia Cecere, Luana Calabrò, Francesco Callegarin, Paola Del Bianco, Gian Luca De Salvo, Federica Pezzuto, Fiorella Calabrese, Valentina Guarneri, Andrea Dell’Amore, Federico Rea

Abstract

Pleural mesothelioma (PM) is a rare asbestos-related malignancy characterized by complex diagnosis and poor prognosis, with survival strongly influenced by histological subtype and eligibility for a multimodality approach, reserved for highly selected patients. While platinum-pemetrexed chemotherapy or the combination of ipilimumab plus nivolumab represent standard first-line options for unresectable disease, pembrolizumab combined with platinum-pemetrexed has demonstrated improved survival in advanced PM (IND227/Keynote483 trial). In resectable PM, multimodality treatment including surgery and chemotherapy remains preferred, yet pathological complete response (pCR) rates remain low at approximately 5%, and the role of perioperative immunotherapy is still poorly defined. CHIMERA is a prospective, open-label, multicenter phase II single-arm trial evaluating neoadjuvant pembrolizumab combined with platinum-pemetrexed chemotherapy followed by surgery and adjuvant pembrolizumab in patients with treatment-naïve, resectable stage I-IIIA epithelioid or biphasic PM. Patients receive three cycles of neoadjuvant pembrolizumab plus cisplatin or carboplatin and pemetrexed every three weeks, followed by centralized pleurectomy/decortication or extended pleurectomy/decortication in two high-volume referral centers, and subsequently 14 cycles of adjuvant pembrolizumab. The primary endpoint is pCR, with secondary endpoints including major pathological response, objective response rate, event-free survival, overall survival, treatment feasibility, and safety; translational tissue- and blood-based biomarker analyses are planned. The study is powered to detect an increase in pCR from 5% to 18%, requiring 40 patients to account for potential dropouts. By focusing on pathological efficacy within a standardized multimodality framework, CHIMERA aims to clarify the role of perioperative chemo-immunotherapy and to improve outcomes for patients with resectable PM.