Programmed cell death protein receptor and ligands in haematological malignancies - Current status

Recent Advances in the Therapeutic Management of Advanced Systemic Mastocytosis

Advanced systemic mastocytosis (AdvSM) is a rare haematological neoplasm characterised by the accumulation of neoplastic mast cells (MCs) in various organs, resulting in organ dysfunction and reduced life expectancy. The subtypes include aggressive SM (ASM), SM with an associated haematological neoplasm (SM-AHN) and mast cell leukaemia (MCL). The gain of function KIT D816V mutation is present in most cases. The availability of tyrosine kinase inhibitors (TKIs) has revolutionised the treatment landscape for patients with this life-limiting disease. Patients are now able to achieve molecular remission, improved quality of life and improved overall survival. This review focuses on the targeted therapies currently available in clinical practice and within the clinical trial setting for AdvSM. This review also highlights possible future therapeutic targets and discusses therapeutic strategies for this multimutated and clinically heterogeneous disease.

Expression of PD1 and PDL1 as immune-checkpoint inhibitors in mantle cell lymphoma

BACKGROUND

Mantle cell lymphoma (MCL) has remained incurable in most patients. The expression of PD-L1 as a prognostic and predictive marker has not been fully evaluated in MCL. The current study aimed to determine PD-1/PD-L1 expression in MCL specimens and its significance as an immune check point inhibitor.

METHODS

This retrospective study was conducted on the formalin-fixed paraffin-embedded blocks of 79 confirmed MCL patients based on immunohistochemistry (IHC). The IHC method was used to stain patient samples for PD1 and PDL1. Positive PD-1/PD-L1 expression was defined as moderate to strong or memberanous or memberanous/cytoplasmic staining in at least 5% of tumor and/or 20% of associated immune cells. Tumor aggressiveness was determined based on Ki67 and variant.

RESULTS

The mean age of the patients was 60.08 ± 10.78 years old. Majority of the patients were male. The prevalence of aggressive tumor was 25%. Positive PD1 and PDL1 expression were identified in 12 (15.0%) and 3 (3.8%) of tumor cells, respectively. PD1 and PDL1 were positive in zero (0%) and 7 (8.9%) of background cells, respectively. There was no significant difference in terms of study parameters between positive and negative groups for both PD1 and PDL1 proteins. PD1 tumor cell percentage was negatively correlated with age (r = -0.254, p = 0.046).

CONCLUSION

Our results suggest that neither PD-1 nor its ligands represent relevant targets for MCL treatment. Age may impact the efficiency of immune checkpoint inhibitors and could be related to the increased incidence of MCL with age.

Exceptional response to nivolumab of a heavily pre-treated patient with metastatic renal-cell cancer: from a case report to molecular investigation and future perspectives

Immunotherapy may result in long-lasting exceptional clinical responses, the molecular background of which is inadequately understood. Here, we present the case of a 63-year-old patient with a past medical history of renal cancer who relapsed many years later. Several treatment lines were administered prior to immunotherapy, which was administered in the ninth line, achieving complete remission which had lasted for more than 3 years. Genomic alterations, tumor mutational burden (TMB), and microsatellite instability as well as PD-L1, MLH1, MSH2, MSH6, PMS2, CD3, CD8, CD20, CD138, CD1a, and FoxP3 expression were assessed in primary and metastatic tumors. Primary and metastatic tumors were microsatellite stable with high TMB, while somatic mutations in MLH1 and TP53 genes were detected, respectively. Although the primary tumor was negative for PD-L1 expression, the lung metastasis was positive. Interestingly, metastasis displayed a dramatically increased infiltration by CD1a-positive dendritic cells in addition to increased CD3+ and CD8+ cytotoxic T cells. Increased infiltration of the metastatic tumor by CD1a+ antigen presenting cells warrants further investigation to assess its potential predictive value.

PD-L1 Expression in Mastocytosis

Programmed death 1 (PD-1), when activated by its ligands PD-L1 and PD-L2, suppresses active immune cells in normal immune regulation to limit autoimmunity and, in tumors, as a mechanism of immune evasion. PD-L1 expression has been described as both a prognostic and predictive marker in many solid and hematologic neoplasms, as targeted therapies against the PD-1/PD-L1 interaction have gained clinical importance. PD-L1 expression has been assessed in a few studies on mastocytosis. We review this literature and the need for further investigation of the tumor-immune interaction in mastocytosis.