P-166: Prognostic impact of response-adjusted ISS score in Multiple Myeloma

Abstract

<h3>Background</h3> One of the most powerful prognostic indicators in patients (pts) with multiple myeloma (MM), along with International Staging System (ISS) and recently adapted Revised ISS score (R-ISS), is achievement of complete remission (CR) <h3>Aim</h3> The aim of study was to analyze prognostic significance of Response-adjusted ISS (RaISS) in transplant ineligible MM pts <h3>Method</h3> The study included 257 newly diagnosed, transplant ineligible MM pts, diagnosed during period 2012-2020 (129 male; 128 female, mean age 66 yrs, range 35-85 yrs). The IgG MM existed in 155pts (60.3%), IgA in 50 (19.5%), BJ in 43 (16.7%), IgD in 3 (1.2%) and IgM in 1pt (0.4%). According to the clinical stage (CS, Durie-Salmon), III CS was present in 207pts (80.5%); II in 38pts (14.8%); and I CS in 10pts (3.9%). Renal impairment was present in 82pts (31.9%) and elevated LDH in 58pts (22.6%). The ISS score 1 had 55pts (21.4%), ISS2 65pts (25.3%) and 137pts (53.3%) had ISS3. According to the Revised ISS (R-ISS) score, R-ISS1 was found in 40pts (15.6%), R-ISS2 in 164pts (63.8%), while R-ISS3 was present in 53pts (20.6%). Treatment with triple thalidomide (Thal) based chemotherapy (HT) was applied in 129pts (50.2%) with standard risk features (R-ISS1), while bortezomib (Bz) based triplets were applied in 95pts (37%) with high risk features (R-ISS2 and R-ISS3). Standard HT was applied in 33pts (12.9%). <h3>Results</h3> Considering RaISS score, the group of pts treated with Thal-based HT consisted of: 15pts (11.6%) with low risk (RaISS 0-1); 65pts (50.4%) with intermediate risk (RaISS 2-3); and high risk (RaISS 4) in 49pts (40.3%). There was significant difference in PFS (Log Rank 7.197; p=0.027), and, even more pronounced, in OS (log Rank 22.192; p=0.000) between low risk pts (RaISS 0-1), and intermediate or high risk pts (RaISS 2-3; RaISS 4), treated with Thal-based HT. The distribution according the RaISS score in patients treated with Bz-based combos was as follows: low risk - 11pts (11.6%); intermediate - risk 36pts (37.9%); high risk- 48pts (50.5%). Although there was no difference in PFS (Log Rank 3.307; p=0.191), pts of low risk, with RaISS score 0-1, had significantly longer OS (Log Rank 13.894; p=0.001) in comparison to the pts of intermediate and high risk (RaISS ≥2), treated with Bz-based triplets. There was no difference in PFS (Log Rank 0.008; p=0.930) or OS (Log Rank 0.502; p=0.479) between pts with RaISS 4, and pts with R-ISS 3 (Log Rank 0.008; p=0.930) treated with Thal-based HT. Likewise, no difference was found considering PFS (Log Rank 0.168; p=0.682) and OS (Log Rank 0.923; p=0.337) in patients treated with Bz-based triplets with RaISS 4 in comparison to the pts with R-ISS3. <h3>Conclusion</h3> RaISS score is simple and powerful prognostic index, indicating necessity of tailored treatment in accordance to the R-ISS score with final goal to overcome high-risk features in patients with multiple myeloma.