Oncolytic herpes simplex virus type 1 (HSV-1) in combination with lenalidomide for plasma cell neoplasms

Oncolytic viruses exert an anti-tumour effect through two mechanisms: direct oncolytic and indirect immune-mediated mechanisms. Although oncolytic herpes simplex virus type 1 (HSV-1) has been approved for melanoma treatment and is being examined for its applicability to a broad spectrum of malignancies, it is not known whether it has an anti-myeloma effect. In the present study, we show that the third-generation oncolytic HSV-1, T-01, had a direct oncolytic effect on five of six human myeloma cell lines in vitro. The anti-tumour effect was enhanced in the presence of peripheral blood mononuclear cells (PBMCs) from healthy individuals and, to a lesser extent, from patients with myeloma. The enhancing effect of PBMCs was abrogated by blocking type I interferons (IFNs) or by depleting plasmacytoid dendritic cells (pDCs) or natural killer (NK) cells, suggesting that pDC-derived type I IFNs and NK cells dominated the anti-tumour effect. Furthermore, the combination of T-01 and lenalidomide exhibited enhanced cytotoxicity, and the triple combination of T-01, lenalidomide and IFN-α had a maximal effect. These data indicate that oncolytic HSV-1 represents a viable therapy for plasma cell neoplasms through direct oncolysis and immune activation governed by pDCs and NK cells. Lenalidomide is likely to augment the anti-myeloma effect of HSV-1.

Atypical IgG4+ Plasmacytic Proliferations and Lymphomas: Characterization of 11 Cases

OBJECTIVES

To report the clinicopathologic features of monotypic immunoglobulin G4+ (IgG4+) lymphoid and plasmacytic proliferations.

METHODS

Cases were identified from the pathology files. Pathology and clinical materials were reviewed.

RESULTS

Eleven cases of monotypic IgG4+ proliferations were identified at nodal, orbital, or salivary sites. Six cases (three men, three women; age, 57-94 years) met criteria for lymphoma or plasma cell neoplasia. Most contained frequent Mott cells. Five cases (three men, two women; age, 40-80 years) had restricted proliferations of atypical/monotypic IgG4+ plasma cells in a background of reactive lymphoid hyperplasia or inflammation.

CONCLUSIONS

Monotypic IgG4+ proliferations include lymphomas, plasmacytic neoplasms, and a previously uncharacterized group of proliferations not meeting criteria for conventional hematolymphoid neoplasia. Distinct features included prominent Mott cells and/or monotypic plasma cells within follicles. The proliferations were infrequently associated with IgG4-related disease (IgG4-RD). Our findings raise questions regarding the relationship between clonal IgG4+ proliferations, reactive/inflammatory processes, and IgG4-RD.

A counting strategy for estimating plasma cell number in CD138-stained bone marrow core biopsy sections

Plasma cells are readily identified microscopically after immunostaining for the CD138 antigen, and CD138-stained bone marrow core biopsy sections have proved superior to Giemsa-stained aspirate smears and hematoxylineosin (H&E) sections for determining plasma cell percentages in marrow. The CD138-stained plasma cell percentage is generally obtained by visual estimation, after viewing the entire section. We propose an alternative method, in which the microscopist initially views the immunostained section under low- and medium-power magnification, then selects a single high-power field in which the relative concentration of plasma cells appears most representative of the section as a whole, and performs a manual differential count of plasma cells in that field. On 44 CD138-stained core biopsy specimens from patients with plasma cell myeloma, selected area counting provided plasma cell percentage values that were more closely correlated with total section plasma cell area, determined by computerized image cytometry, than were visual estimates. This simple method requires only slightly more time than visual appraisal, does not require extensive training or experience, and appears to provide a more accurate estimate of the plasma cell population within the entire specimen.