Can Monosomy 7 be Targeted By Next Generation Cereblon-Modulating Agents?

• Published in: Blood 2019-11, Vol.134 (Supplement_1), p.1270-1270
• Main Authors: Adema, Vera, Kerr, Cassandra M, Walter, Wencke, Hutter, Stephan, Nagata, Yasunobu, Awada, Hassan, Kongkiatkamon, Sunisa, Snider, Christina A., Co, Milo, Magdalena, Rainey, Durmaz, Arda, Meggendorfer, Manja, Nazha, Aziz, Scott, Jacob, Carraway, Hetty E., Sekeres, Mikkael A., Sole, Francesc, Haferlach, Torsten, Visconte, Valeria, Maciejewski, Jaroslaw P.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2019-128967

Genomic advances have initiated a new era of precision oncology. Targeted therapeutics can rationally select potentially responsive patient populations and exclude resistant patients based on molecular mechanisms of action. The application of immunomodulatory drugs (IMiDs) evolved from unselective usage to the identification of del(5q) as a target, which then led to mechanistic clues and clarification of its mode of action. Lenalidomide (LEN) has been used in non del(5q) patients with a variable response rate, but the molecular underpinnings for LEN efficacy in this setting are not known. Genomic analyses (Negoro et al., Leukemia 2016) have provided only a marginal improvement in response prediction, suggesting that other factors might be relevant in sensitizing cells to LEN. The effects of LEN are related to its binding affinity to cereblon (CRBN), the substrate adaptor of the CRL4CRBN E3 ubiquitin ligase, a cullin-ring ligase consisting of damaged DNA-binding protein1(DDB1), cullin4a (CUL4A), and regulator of cullins-1 (ROC1). LEN selectively activates CRL4CRBN E3 ubiquitin ligase to selectively degrade CSNK1A1 leading to synthetic lethality in patients with del(5q) that are haploinsufficient (HI) for CSNK1A1. However, LEN and the new generation compounds pomalidomide and iberomide (CC-220) also trigger recruitment and degradation of the zinc finger transcription factors IKAROS (IKZF1, 7p12.2) and AIOLOS (IKZF3, 17p12-q21.1) through CRBN, and therefore promote their proteosomal degradation. The synthetic lethality of these immunomodulator agents relies on expression levels of AIOLOS and IKAROS. Response to those agents depends strictly on low expressions of AIOLOS and IKAROS sensitizing certain cell types (e.g., myeloma). We hypothesized that levels of LEN sensitivity might correlate with expression levels of its targets in selected disease subtypes of myeloid neoplasia (MN). We studied a large cohort of patients with MN (n=3,328) and we identified 122 patients with -7 and 194 patients with del(7q). We noted that for those cases with informative RNA-seq expression, IKAROS exhibited haploinsufficient (HI) mRNA levels in 67% of patients with -7 and 40% in del(7q), as defined based on levels