471PLurbinectedin (LUR) in combination with irinotecan (IRI) in patients (pts) with advanced solid tumours

Abstract Background LUR is a new agent that exerts antitumor activity through inhibition of trans-activated transcription and modulation of tumor microenvironment. Preclinical synergism/additivity in combination with IRI has been reported, thus prompting the conduct of this trial. Methods Phase I trial to evaluate escalating doses of LUR on Day (D) 1 plus a fixed dose of IRI 75 mg/m2 on D1 and D8 every 3 weeks (q3w) in pts with advanced solid tumors, enrolled following a standard 3 + 3 dose escalation design. Results 39 pts were treated at 5 dose levels (DL); 13 at the recommended dose (RD). 56% were females, 69% had ECOG PS = 1; median age was 58 years; median of 2 prior chemotherapy lines for advanced disease (range, 0 − 4) per pt. RD was defined as LUR 2.0 mg/m2 on D1 + IRI 75 mg/m2 on D1 and D8 q3w + GCSF. Dose-limiting toxicities in Cycle 1 were observed in 2/3 evaluable pts at the maximum tolerated dose (MTD) and in 3/13 evaluable pts at the RD. At the MTD and the RD, DLTs were skipping IRI D8 doses due to grade (G) 3-4 neutropenia (n = 3 patients) or G2-4 thrombocytopenia (n = 2). At the RD common G1/2 toxicities were nausea, vomiting, fatigue, diarrhea, anorexia and neuropathy; G3/4 hematological abnormalities comprised neutropenia (33%), but no thrombocytopenia. Objective RECIST responses were documented in 6/34 evaluable pts (18%): 3/11 pts with small cell lung cancer (SCLC), 2/2 pts with endometrial carcinoma (EC) and 1/3 pts with glioblastoma (GB). Most responses (5/12 evaluable patients [42%]) were at the RD. One pt with EC has an ongoing PR after 20 cycles. Prolonged SD > 4 months were observed in pancreatic carcinoma (3/6 pts), soft tissue sarcoma (STS) (5/9 pts) and SCLC (6/11, including 4 with SD for 6, 9, 11 and 26+ months). Conclusions The combination of LUR and IRI is well tolerated, with no unexpected toxicities. Myelosuppression was dose-limiting, but predictable and manageable. The RD is LUR 2.0 mg/m2 on D1 + IRI 75 mg/m2 on D1 and D8 q3w with GCSF. Notable antitumor activity was observed, especially in SCLC, EC, GB and STS. Expansion in these indications is warranted. Clinical trial identification NCT02611024. Legal entity responsible for the study PharmaMar SA. Funding PharmaMar. Disclosure S. Ponce Aix: Advisory / Consultancy: Roche; Speaker Bureau / Expert testimony: Roche, BMS, MSD. G. Cote: Advisory / Consultancy: Agios; Research grant / Funding (institution), Research funding to my institution for the conduct of clinical trials; no salary support: Epizyme, Eisai, Macrogenics, Boston Biomedical, Plexxicon, Merck KGaA/EMD Serono Research and Development Institute, CBA Inc, Bayer. R. Nunez: Shareholder / Stockholder / Stock options, Full / Part-time employment: PharmaMar. M. Siguero: Shareholder / Stockholder / Stock options, Full / Part-time employment: PharmaMar. M. Insa: Full / Part-time employment: PharmaMar. M. Cullell-Young: Shareholder / Stockholder / Stock options, Full / Part-time employment: PharmaMar. C. Kahatt: Shareholder / Stockholder / Stock options, Full / Part-time employment: PharmaMar. A. Zeaiter: Shareholder / Stockholder / Stock options, Full / Part-time employment: PharmaMar. L. Paz-Ares: Advisory / Consultancy: Amgen; AstraZeneca; Boehringer Ingelheim; Bristol-Myers Squibb; Clovis Oncology; MSD; Novartis; Pfizer; Roche; Takeda. All other authors have declared no conflicts of interest.