Page 182 - 2022_03-Haematologica-web

Letters to the Editor
vation, such as those with cryopyrin-associated periodic syndrome and Schnitzler syndrome.8 Capturing elevated circulating interleukin-1β, the typical downstream effec- tor of inflammasome activation, is less practical given its very short half-life9 and it is virtually undetectable in plas- ma even in patients with active cryopyrin-associated peri- odic syndrome and Schnitzler syndrome.8 Peripheral blood plasma ASC speck levels are almost exclusively ele- vated in patients with lower-risk MDS, compared to other hematologic malignancies, and like the myeloid-related inflammatory protein S100A9, provide an index of the magnitude of medullary pyroptosis.4,10 In the current study, we explored whether peripheral blood plasma ASC speck level may serve as a biomarker of response in lower-risk MDS patients who received lenalidomide with or without epoetin β.
Peripheral blood plasma samples collected at the time of enrolment were available from 69 of 99 patients with International Prognostic Scoring System (IPSS) low- or intermediate-1-risk (i.e., lower-risk), non-deletion (5q) MDS who were enrolled in the GFM-Len-Epo-08 trial and completed four cycles (16 weeks) of study treatment. This Groupe Francophone des Myelodysplasies trial, registered as NCT01718379, was a randomized multicenter phase III study in transfusion-dependent lower-risk MDS patients comparing treatment with lenalidomide to the combination of lenalidomide and epoetin β. All patients had failed to respond to or relapsed after initial treatment with recombinant erythropoietin. Hematologic improve- ment of erythroid lineage (HI-E), the primary endpoint of the study, was evaluated after four cycles of treatment according to International Working Group 2006 criteria. Further details of the trial were described previously.2 The mean percentage of ASC specks was measured in periph- eral blood plasma using flow cytometry and its level was glucose-adjusted with log10-transformation to adjust for hyperglycemia-induced inflammasome activation.10,11 Covariates associated with HI-E were analyzed using binary logistic regression by including variables with clin- ical and statistical relevance in univariate analysis (P<0.05) into the multivariate model. Interactions between variables and treatment were assessed by the Gail-Simon test. SPSS 26 (Armonk, NY, USA) and R 4.0.3 (R Core Team) were used for statistical analyses. This study was approved by the institutional review board.
The median age of the 69 patients at enrolment was 73 years (range, 46-86) and 69.6% were male (Online Supplementary Table S1). Based on the World Health Organization 2008 classification, 38 patients (55.1%) had refractory anemia with ring sideroblasts. Conventional karyotype was classified as favorable in 59 of 68 patients (86.8%) according to the classical IPSS. The median num- ber of mutations in each patient was two (range, 0-6). Mutations in SF3B1 and TET2 were detected in 52 (75.4%) and 34 (49.3%) patients, respectively. Lenalidomide and lenalidomide plus epoetin β were administered to 31 and 38 patients, respectively. After completion of 16 weeks of study treatment, 7 of 31 (22.6%) and 21 of 38 (55.3%) patients achieved a HI-E (P=0.006). Comparison of response according to baseline clinical parameters showed a significantly higher frequen- cy of elevated ASC specks (defined as above the median level, 71.4% vs. 34.1%, P=0.002) but less frequent eleva- tion of serum erythropoietin level (defined as >200 mU/mL, 28.6% vs. 60.0%, P=0.029) in responders. Although limited by sample size, a higher frequency of elevated ASC specks was consistently found in respon- ders compared to non-responders of each treatment arm (lenalidomide, 57.1% vs. 29.2%, P=0.210; lenalidomide
Figure 1. Erythroid response stratified by status of biomarkers. ASC: apopto- sis-associated speck-like protein containing a CARD; sEPO, serum erythropoi- etin.
plus epoetin β, 76.2% vs. 41.2%, P=0.046). DNMT3A was more frequently mutated in responders, but the difference was not statistically significant (28.6% vs. 12.2%, P=0.120). Other baseline parameters, including bone mar- row blast percentage, karyotype classification and num- bers of mutations, were also not significantly different between responders and non-responders (Table 1). In the multivariate analysis including ASC specks and serum erythropoietin, and adjusted for DNMT3A mutational sta- tus1,12 and treatment arm, both elevated ASC specks (odds ratio [OR]=4.963, 95% confidence interval [95% CI]: 1.445-17.045, P=0.011) and serum erythropoietin (OR=0.119, 95% CI: 0.025-0.561, P=0.007) were inde- pendently associated with HI-E. As expected, combined treatment remained significant (OR=6.535, 95% CI: 1.622-26.334, P=0.008). Of note, there was no significant interaction between each of these two biomarkers and treatment arm. Of 56 patients with both biomarkers avail- able at inclusion, elevation in ASC specks showed a sen- sitivity and specificity of 71.4% and 74.3%, respectively, to predict HI-E, and addition of serum erythropoietin could improve the specificity to 88.6% with a reduction of sensitivity to 42.9%. No response (0.0%) was observed in patients with low ASC specks plus elevated serum ery- thropoietin, while the response rate was 69.2% in those with elevated ASC specks plus low serum erythropoietin (P<0.001) (Figure 1).
Ineffective erythropoiesis is a hallmark of lower-risk MDS, and NLRP3 inflammasome-directed pyroptosis serves as a common underlying driver licensed by both the extrinsic proinflammatory cytokine milieu and intrin- sic somatic mutations.3,4 Compared to single-agent treat- ment, lenalidomide with recombinant erythropoietin pro- duces a higher rate of erythroid response.1,2 Our study showed that elevation of ASC specks, a specific and meas- urable surrogate of pyroptosis, was independently predic- tive of this response. Moreover, the lower serum erythro- poietin in responders may similarly reflect suppression of erythropoietin liberation in response to anemia by pyrop- totic inflammatory proteins. Levels of the myeloid-related inflammatory protein S100A9 increase directly with ASC specks in lower-risk MDS, and similarly serve as an index of the extent of medullary pyroptosis. S100A9 suppresses erythropoietin release in vitro in HepG2 hepatoma cells and its levels in lower-risk MDS patients correlate inverse- ly with serum erythropoietin concentration, supporting the notion that inflammatory cytokines also suppress ery- thropoietin production in vivo.13 These observations sug- gest that patients with greater medullary inflammasome
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haematologica | 2022; 107(3)