e12507 Background: T-DM1 is widely used in HER2 positive metastatic breast cancer (MBC) patients (pts), often for many cycles until progression. However, little is known about its long term toxicity. The aim of this study was to evaluate the safety profile of T-DM1 when delivered for ≥12 cycles. Methods: HER2 positive MBC pts who had received ≥12 cycles of T-DM1 across 18 Italian cancer centers were enrolled from January 2017 to September 2018. The 12 cycles cut-off was chosen based on the EMILIA trial median PFS (9.6 months), to identify a patient population treated with T-DM1 for longer time. Tumor and clinical characteristics were collected. Standard haematological tests, blood chemistries and side effects (nausea, vomiting, diarrhea, stomatitis, asthenia) were recorded cycle by cycle, according CTCAE criteria version 4. Haematological and laboratory toxicities were available for 86 patients, while other toxicities for all 115 patients. Results: Overall, 115 pts were enrolled. Median age was 54.5 (range 29.6–81.9); median time from diagnosis of metastatic disease to first T-DM1 cycle was 32.5 months. T-DM1 was administered as 2nd line and 3rd line of treatment in 45.2% and 27.8% of pts, respectively. Median number of cycles was 18 (range 12-59). Complete response, partial response and stable disease rates were 11.4%, 43% and 45.6%, respectively. Treatment related side effects are shown in table 1. Interestingly, no increased liver toxicity was observed in pts with liver metastases. Analysis of mean CTCAE grade by cycle showed that no relevant incremental toxicity was observed during long term T-DM1 therapy. Conclusions: T-DM1 is safe and well tolerated in these long responding pts. We found no relevant cumulative toxicity. Patients should be treated with T-DM1 as long as their tumor responds, as no safety issues are related to its long term use. [Table: see text]
3116 Background: MBC is an incurable disease and therefore treatment focuses mainly on prolonging pts survival and improving quality of life. Eribulin (E) is a microtubule inhibitor that increased overall survival in pretreated pts. E peripheral N is reported in 13.9-35% of cases. PAINTER main objective was to survey tolerability of E in real life in MBC, while secondary endpoints were to investigate the relationships between specific genetic polymorphisms and incidence and severity of peripheral N. Methods: This is a multicenter, interventional, single-arm, phase IV study, that enrolled pts who received E after taxanes and antracyclines (dose 1.4 mg/m2 day 1, 8 every 21 days). PAINTER study follow-up is still ongoing. Genomic DNA was isolated from whole blood samples (Maxwell whole blood DNA kit. Promega). 15 SNPs (Single Nucleotide Polymorphisms) were genotyped by Taqman specific assays. For SNPs analysis, we selected pts with avaliable clinical data and who completed E treatment. N was evaluated by medical examination. The associations between peripheral N (any grade) and the selected polymorphisms were evaluated with Fisher exact test. Results: From May 2014 to June 2018, 180 pts were enrolled in the PAINTER study from 20 Italian hospitals and 135 were analysed for the present report. Pts and tumor characteristics were as follow: median age 62 years (31-85), ductal carcinoma 78.5%, visceral disease 70.4%, luminal type 62.6%, Her2 positive 20.3%, triple negative 17.1%, previous median treatment lines for MBC 5 (0-18), previous N reported in 17.8% of pts (sensory 87.5%, motor 12.5%). N (all grades) were reported in 33.4% of patients (G3-G4: 3%). Among the selected SNPs, one allelic variant (rs2233335 G/G versus G/T or T/T) in NDRG1 gene had a statistically significant association with N (p 0.0010). Conclusions: The data reported demonstrate for the first time that the allelic variant rs2233335 (G/T and T/T) in NDRG1 gene correlates with E induced N. These data, if corroborated, will allow a tailored treatment with E. Clinical trial information: NCT02864030. [Table: see text]
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