At the American Association for Cancer Research (AACR) annual meeting in Washington, DC, USA, on Tuesday 4th April, a poster session titled “Clinical Laboratory and Imaging Correlates” took place.
One of the posters on display (3724 / 9) was titled “PDL1 protein expression and tumor mutation burden in hematologic malignancies: correlation with Hodgkin and high grade lymphoma” by Lina Abdul Karim, from MedStar Georgetown University Hospital, Washington DC, and colleagues.
Immunostaining using the FDA approved PD-L1 IHC 22C3 pharmDx assay was carried out on formalin fixed paraffin embedded sections from 92 hematological malignancies including Hodgkin Lymphoma (HL), Diffuse Large B-Cell Lymphoma (DLBCL), Low-Grade Non-Hodgkin Lymphoma (LGNHL), as well as Acute Myeloid Leukemia (AML), Acute Lymphoblastic Leukemia (ALL), and Myeloma. Partial or complete membrane staining in all viable tumor cells was scored as follows: <1% negative, 1–49% low level, and >50% high level PD-L1 expression. Comprehensive Genomic Profiling (CGP) was also done in 2,064 cases.
- High PD–L1 expression observed 100% of HL
- Significantly higher PD–L1 positivity was observed in DLBCL versus LGNHL (P = 0.01)
- In CGP analysis, Tumor Mutation Burden (TMB) was significantly higher in DLBCL versus LGNHL (P < 0.0001)
The group concluded their poster by hypothesizing that the high PD-L1 expression in HL and DLBCL, and the high TMB in DLBCL, could potentially enhance responsiveness to check point inhibitor therapy.
- Abdul Karim L. et al. PDL1 protein expression and tumor mutation burden in hematologic malignancies: correlation with Hodgkin and high grade lymphoma [Poster]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; 2017. Poster nr [3724 / 9].