429POutcome of high-grade gliomas (HGGs) treated into immunotherapeutic early-phase clinical trials (ieCTs): A single-center experience

Abstract Background ieCTs historically excluded HGG patients (pts) due to unavailability of serial bioptic sampling, use of corticosteroids, concerns on activity of immunotherapy in central nervous system, and rapid clinical deterioration. Methods Data of all recurrent HGG pts enrolled into ieCTs at the Humanitas Cancer Center Phase I Unit between 2014 and 2019 were retrospectively reviewed. Disease control rate (DCR) according to RANO criteria, six-months progression-free and overall survival (PFS-6; OS-6), and treatment-related adverse events (TRAEs), were evaluated. A control-cohort (CC) of patients treated with standard therapies (temozolomide, fotemustine, lomustine and procarbazine, bevacizumab) matched (1:1) for sex, age, line of treatment, MGMT methylation status, and IDH mutational status, was selected for comparison. A huge series of clinical and laboratory variables with an established prognostic relevance for solid tumors pts treated into ieCTs were studied through univariate analysis. Results Only 5 out 23 ieCTs allowed inclusion of HGG pts. The experimental cohort (EC) consisted of 25 pts (M/F: 16/9; median age: 50 years): 22 (88%) glioblastoma, 3 (12%) anaplastic astrocytoma. 17 pts (68%) required steroid therapy, with a median baseline dexamethasone dose of 2 mg (range 1-6). The median number of prior systemic therapies was 1 (range 1-2). 12 pts (48%) received monotherapies (anti PD-1, anti CSFR-1, anti TGF-s, anti cereblon), 13 (52%) combination regimens (anti PD-L1 + anti CD38, anti PD-1 + anti CSFR-1). DCR was 40% in both EC (1 CR + 2 PR + 7 SD) and CC (1 PR + 9 SD). 4 pts (16%) in EC had grade ≥3 TRAEs (1 neutropenia, 1 pneumonia, 2 hepatitis). With a median follow-up (FU) of 14 months PFS-6 were 35% and 16% (p = 0.075), in EC and CC respectively, while OS-6 was significantly improved in the EC (82% vs 44%, p = 0.004). With limitations due to small sample size, short FU and few events recorded, none of the parameters analyzed resulted prognostic. Conclusions Survival of our HGG pts treated into ieCTs compared favorably with a matched CC. Inclusion of HGGs pts into ieCTs should be encouraged. Clinical selection factors predicting which pts may benefit most still lack. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure M. Simonelli: Advisory / Consultancy: AbbVie. A. Santoro: Advisory / Consultancy: BRISTOL-MYERS-SQUIBB; Advisory / Consultancy: SERVIER; Advisory / Consultancy: GILEAD; Advisory / Consultancy: EISAI; Advisory / Consultancy: BAYER; Advisory / Consultancy: MERCK SHARP & DOHME; Speaker Bureau / Expert testimony: TAKEDA; Speaker Bureau / Expert testimony: BRISTOL-MYERS-SQUIBB; Speaker Bureau / Expert testimony: ROCHE; Speaker Bureau / Expert testimony: ABBVIE; Speaker Bureau / Expert testimony: AMGEN; Speaker Bureau / Expert testimony: CELGENE; Speaker Bureau / Expert testimony: SERVIER; Speaker Bureau / Expert testimony: GILEAD; Speaker Bureau / Expert testimony: ASTRAZENECA; Speaker Bureau / Expert testimony: PFIZER; Speaker Bureau / Expert testimony: ARQULE; Speaker Bureau / Expert testimony: LILLY; Speaker Bureau / Expert testimony: SANDOZ; Advisory / Consultancy: PFIZER. All other authors have declared no conflicts of interest.