European Myeloma Network perspective on CAR T-Cell therapies for multiple myeloma

Chimeric antigen receptor (CAR) T cells (CAR-T) have dramatically changed the treatment landscape of B-cell malignancies, providing a potential cure for relapsed/refractory patients. Long-term responses in patients with acute lymphoblastic leukemia and non Hodgkin lymphomas have encouraged further development in myeloma. In particular, B-cell maturation antigen (BCMA)-targeted CAR-T have established very promising results in heavily pre-treated patients. Moreover, CAR-T targeting other antigens (i.e., SLAMF7 and CD44v6) are currently under investigation. However, none of these current autologous therapies have been approved, and despite high overall response rates across studies, main issues such as long-term outcome, toxicities, treatment resistance, and management of complications limit as yet their widespread use. Here, we critically review the most important pre-clinical and clinical findings, recent advances in CAR-T against myeloma, as well as discoveries in the biology of a still incurable disease, that, all together, will further improve safety and efficacy in relapsed/refractory patients, urgently in need of novel treatment options.

The avoidance of G-CSF and the addition of prophylactic corticosteroids after autologous stem cell transplantation for multiple myeloma patients appeal for the at-home setting to reduce readmission for neutropenic fever

BACKGROUND

Autologous stem cell transplantation (ASCT) remains the standard of care for young multiple myeloma (MM) patients; indeed, at-home ASCT has been positioned as an appropriate therapeutic strategy. However, despite the use of prophylactic antibiotics, neutropenic fever (NF) and hospital readmissions continue to pose as the most important limitations in the outpatient setting. It is possible that the febrile episodes may have a non-infectious etiology, and engraftment syndrome could play a more significant role. The aim of this study was to analyze the impact of both G-CSF withdrawal and the addition of primary prophylaxis with corticosteroids after ASCT.

METHODS

Between January 2002 and August 2018, 111 MM patients conditioned with melphalan were managed at-home beginning +1 day after ASCT. Three groups were established: Group A (n = 33) received standard G-CSF post-ASCT; group B (n = 32) avoided G-CSF post-ASCT; group C (n = 46) avoided G-CSF yet added corticosteroid prophylaxis post-ASCT.

RESULTS

The incidence of NF among the groups was reduced (64%, 44%, and 24%; P<0.001), with a non-significant decrease in hospital readmissions as well (12%, 6%, and 2%; P = 0.07). The most important variables identified for NF were: HCT-CI >2 (OR 6.1; P = 0.002) and G-CSF avoidance plus corticosteroids (OR 0.1; P<0.001); and for hospital readmission: age ≥60 years (OR 14.6; P = 0.04) and G-CSF avoidance plus corticosteroids (OR 0.07; P = 0.05).

CONCLUSIONS

G-CSF avoidance and corticosteroid prophylaxis post ASCT minimize the incidence of NF in MM patients undergoing at-home ASCT. This approach should be explored in a prospective randomized clinical trial.

Nectin-2 Expression on Malignant Plasma Cells Is Associated with Better Response to TIGIT Blockade in Multiple Myeloma

PURPOSE

T-cell immunoreceptor with Ig and ITIM domain (TIGIT) blockade could represent an alternative therapeutic option to release the immune response in patients with multiple myeloma. Here we analyzed the expression of TIGIT and its ligands poliovirus receptor (PVR) and nectin-2 in the bone marrow (BM) of patients with monoclonal gammopathies and the efficacy of TIGIT blockade activating antimyeloma immunity.

EXPERIMENTAL DESIGN

Expression levels of TIGIT and its ligands were characterized by flow cytometry and ELISA. TIGIT blockade was analyzed in in vitro functional assays with peripheral T cells. BM cells were studied with NanoString technology, real-time PCR, and ex vivo patient BM cell models.

RESULTS

TIGIT and its ligands are highly expressed in the BM of patients with multiple myeloma, suggesting that may play a role in restraining immune activation. TIGIT blockade depleted FoxP3⁺ Tregs while increasing proliferation of IFNγ-producing CD4⁺ T cells from patients with multiple myeloma. PVR ligation inhibited CD8⁺ T-cell signaling and cell proliferation which could be overcome with anti-TIGIT mAb. However, BM cells showed a remarkable heterogeneity in immune signature. Accordingly, functional ex vivo BM assays revealed that only some patients respond to checkpoint blockade. Thus, response to TIGIT blockade correlated with low frequency of TIGIT⁺ cells and high nectin-2 expression on malignant plasma cells.

CONCLUSIONS

TIGIT blockade efficiently reinvigorated peripheral T cells from patients with multiple myeloma. However, in the BM, the efficacy of blocking anti-TIGIT mAb to achieve tumor cell death may depend on the expression of TIGIT and nectin-2, becoming potential predictive biomarkers for identifying patients who may benefit from TIGIT blockade.