429P - Neurological (NEU) and Cytological (CYT) Response (R) As Early Predictors of Time-To-Progression (TTP) and Overall Survival (OS) in Patients (PTS) with Leptomeningeal Carcinomatosis (LMC) Treated with Intrathecal (I.T) Liposomal Cytarabine (LYC)

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ABSTRACT Background The palliative treatment of LMC involves i.t chemotherapy or supportive care. Lcy is a slow-releasing cytarabine formulation approved for leptomeningeal involvement of hematological malignancies. In pts with LMC from solid tumors interesting Neu and Cyt R rates after i.t Lcy have been observed. However, the potential use of those responses as early predictors of TTP and OS has never been explored. Here we show how both Neu and Cyt R can precociously predict a longer TTP and OS. Patients and methods: Twenty-seven pts with LMC consecutively treated at our institution with i.t Lcy under compassionate use (17/27 female), were studied. All pts received i.t Lcy (50 mg) every 2 weeks (w) during induction and every 4 w during maintenance. Neu and Cyt responses were assessed before every Lcy cycle. Results The predominant primary tumor origin was breast (15/27), followed by gastrointestinal (3), lung (3), brain (2), and 4 other organs. A complete Neu R (resolution of all Neu symptoms) was seen in 3/27 pts; partial R (improvement of >50% of Neu symptoms for >2 w) in 6/27 pts; stable disease (no change in Neu symptoms) in 8/27 pts and progressive disease (progression or appearance of new Neu symptoms) in 10/27 pts. The Cyt assessment was available in 9/27 pts with a Cyt complete R confirmed in 7/9 pts. The median time to Neu and Cyt R was 15 days (d) and 14 d, respectively. The overall median TTP was 22 d and the median OS was 41 d. In a subgroup analysis regarding the type of R achieved with the treatment, the median TTP and OS for pts showing a combined Neu and Cyt R were significantly longer compared to those in pts showing both, Neu and Cyt progression as shown in table 1. The most frequently reported adverse event was grade 2 headache with no grade 4 toxicities. Conclusions For the first time, Neu and Cyt R are shown to be early predictors of TTP and OS in pts receiving i.t Lcy for LMC. This result could help to early select patients most likely to benefit from i.t Lcy and to consider discontinuation when very poor prognosis is estimated. Neu R Cyt R TTP (d) OS (d) p Yes Yes 122 141 0.001 Yes No 14 32 0.001 No Yes 42 72 0.001 No No 3 3 0.001 Disclosure All authors have declared no conflicts of interest.