Relapsing thrombotic thrombocytopenic purpura with low ADAMTS13 antigen levels: An indication for splenectomy?

With more recent modalities of immunosuppression, splenectomy is now rarely considered in refractory/relapsed thrombotic thrombocytopenic purpura (TTP). However, the surgical approach had shown convincing evidences of high efficacy in the pre-rituximab era and therefore may still represent a lifesaving option in selected challenging cases. To define the characteristics of subjects who may benefit from splenectomy may ease clinical decision making. In this paper we describe the clinical and laboratory data of 2 multiple relapsing TTP cases who successfully underwent splenectomy in the pre-rituximab era. Whereas high anti-ADAMTS13 antibody titre and low ADAMTS13 activity never correlated with remission and relapse, a drop in the ADAMTS13 antigen level was always associated with the acute phase, whereas levels consistently returned to normal following splenectomy, heralding long term remission. Splenectomy may therefore be considered in refractory TTP cases associated with increased ADAMTS13 antigen clearance, irrespective of persistence of inhibitory antibodies

Correlation between ADAMTS13 activity and neurological impairment in acute thrombotic microangiopathy patients

Differential diagnosis between thrombotic thrombocytopenic purpura (TTP) and other thrombotic microangiopathies (TMA) is usually difficult because of frequently overlapping clinical presentations. Severely depressed ADAMTS13 activity (<10\ua0%) seems distinctive for TTP because of its pathogenetic role. However a long debate exists in the literature about its sensibility and specificity. Our aim was to search for clinical differences between TMA patients referred to our laboratory, comparing them for protease activity\ua0<10 versus\ua0 6510\ua0%. ADAMTS13 activity\ua0 6510\ua0% patients (n\ua0=\ua073) showed a higher prevalence of drug- (p\ua0=\ua00.005) and cancer-associated (p\ua0<\ua00.001) TMA. Mean platelet count and renal dysfunction prevalence was lower (p\ua0<\ua00.001), while neurological impairment was more frequent (p\ua0=\ua00.001) in the\ua0<10\ua0% ADAMTS13 activity group (n\ua0=\ua0109), confirming previous literature findings. When taken neurological manifestations singularly, epilepsy (p\ua0=\ua00.04), focal motor deficit (p\ua0<\ua00.001) and cranial nerve palsy (p\ua0=\ua00.007) were more frequent in the\ua0<10\ua0% activity group. In our case series, a\ua0<10\ua0% ADAMTS13 activity depicts a group of patients with clinical features similar to TTP patients. Focal motor impairment or epileptic manifestations could further address toward a TTP diagnosis. Studies about treatment efficacy and follow-up are advised to determine whether laboratory findings can guide therapeutic decisions

Combined mitoxantrone and anti-TGFβ treatment with PD-1 blockade enhances antitumor immunity by remodelling the tumor immune landscape in neuroblastoma

Background Poor infiltration of functioning T cells renders tumors unresponsive to checkpoint-blocking immunotherapies. Here, we identified a combinatorial in situ immunomodulation strategy based on the administration of selected immunogenic drugs and immunotherapy to sensitize poorly T-cell-infiltrated neuroblastoma (NB) to the host antitumor immune response. Methods 975A2 and 9464D NB cell lines derived from spontaneous tumors of TH-MYCN transgenic mice were employed to study drug combinations able of enhancing the antitumor immune response using in vivo and ex vivo approaches. Migration of immune cells towards drug-treated murine-derived organotypic tumor spheroids (MDOTS) were assessed by microfluidic devices. Activation status of immune cells co-cultured with drug-treated MDOTS was evaluated by flow cytometry analysis. The effect of drug treatment on the immune content of subcutaneous or orthotopic tumors was comprehensively analyzed by flow-cytometry, immunohistochemistry and multiplex immunofluorescence. The chemokine array assay was used to detect soluble factors released into the tumor microenvironment. Patient-derived organotypic tumor spheroids (PDOTS) were generated from human NB specimens. Migration and activation status of autologous immune cells to drug-treated PDOTS were performed. Results We found that treatment with low-doses of mitoxantrone (MTX) recalled immune cells and promoted CD8(+) T and NK cell activation in MDOTS when combined with TGF beta and PD-1 blockade. This combined immunotherapy strategy curbed NB growth resulting in the enrichment of a variety of both lymphoid and myeloid immune cells, especially intratumoral dendritic cells (DC) and IFN gamma- and granzyme B-expressing CD8(+) T cells and NK cells. A concomitant production of inflammatory chemokines involved in remodelling the tumor immune landscape was also detected. Interestingly, this treatment induced immune cell recruitment against PDOTS and activation of CD8(+) T cells and NK cells. Conclusions Combined treatment with low-dose of MTX and anti-TGF beta treatment with PD-1 blockade improves antitumor immunity by remodelling the tumor immune landscape and overcoming the immunosuppressive microenvironment of aggressive NB