Total tumor burden as predictive tool of response and survival of patients with metastatic melanoma treated with nivolumab.

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e21022 Background: Nivolumab (NIVO) has shown increased results either in objective response rate (ORR), progression free survival (PFS) and overall survival (OS), which have completely changed the treatment of patients with metastatic melanoma (MM). Tools to guide selection of patients are absent Methods: This is a retrospective, observational, single-center study. The TBT was calculated considering the sum of the largest diameter of all measurable lesions and the smallest diameter of lymph nodes affected Results: 54 patients with histologiacally confirmed mm were included in the protocol (OCT/14-may/16). Patients had a median age of 61 years (22-86 years), 58% were male, and 73% of tumor were located in the skin. 42% had ECOG 1, 72% had M1c, and 36% had LDH over the upper limit of normality (ULN). 34% had the mutation of the BRAF (half of them treated with IBRAF). About 75% had no prior benefit with anti-CTLA4 and 21% of the population had brain metastases. The median follow-up was 11.1 months and the median NIVO doses was 10 cycles. The ORR was 30.2% and the clinical benefit rate was 54.7%. The median PFS was 6.89 months (95% CI 1.12 to 12.6 months) and OS was not reached. TBT being < or > the median impact on OS with HR 4.5 (95% CI 1.22 to 16.9; p = 0.024). Once again, there was a statistically significant difference in terms of PFS and OS when related to pooled TBT ≤ or > 200 mm. The PFSm was 9.4 months (95% CI NR) for TBT ≤ 200 and 2.6 months ( 95% CI 1.9 to 3.2 months) to TBT > 200, with a HR: 2.64 (95% CI 1.03 to 6.74; p = 0.042). OSm regarding TBT ≤ 200 was not reached and was 2.6 months (95% CI 2.0 to 3.2 months) to TBT > 200, with RH:8.9 (95% CI 2.56 to 30.9; p = 0.001). According to the Fisher's exact test analysis, there is a significant association between LDH > ULN and pooled TBT > 200, with p = 0.023. Also, a relation between grouped TBT ( ≤ 200 or > 200) and the type of response seemed to be significant, with p = 0.021. Conclusions: The results of our study are very consistent with current medical literature. In our study, high TBT was associated with less response rates and both less OS and PFS rates.