CD2⁺ T lymphocytes obtained from either the donor of bone marrow stromal cells (BMSCs) or a third party were cultured in mixed lymphocyte reactions (MLRs) with either allogeneic dendritic cells (DCs) or peripheral blood lymphocytes (PBLs). When autologous or allogeneic BMSCs were added back to T cells stimulated by DCs or PBLs, a significant and dose-dependent reduction of T-cell proliferation, ranging from 60% ± 5% to 98% ± 1%, was evident. Similarly, addition of BMSCs to T cells stimulated by polyclonal activators resulted in a 65% ± 5% (P = .0001) suppression of proliferation. BMSC- induced T-cell suppression was still evident when BMSCs were added in culture as late as 5 days after starting of MLRs. BMSC-inhibited T lymphocytes were not apoptotic and efficiently proliferated on restimulation. BMSCs significantly suppressed both CD4⁺ and CD8⁺ T cells (65% ± 5%, [P = .0005] and 75% ± 15% [P = .0005], respectively). Transwell experiments, in which cell-cell contact between BMSCs and effector cells was prevented, resulted in a significant inhibition of T-lymphocyte proliferation, suggesting that soluble factors were involved in this phenomenon. By using neutralizing monoclonal antibodies, transforming growth factor β1 and hepatocyte growth factor were identified as the mediators of BMSC effects. In conclusion, our data demonstrate that (1) autologous or allogeneic BMSCs strongly suppress T-lymphocyte proliferation, (2) this phenomenon that is triggered by both cellular as well as nonspecific mitogenic stimuli has no immunologic restriction, and (3) T-cell inhibition is not due to induction of apoptosis and is likely due to the production of soluble factors.

We compared a regimen of six chemotherapeutic agents administered sequentially at high doses, followed by myeloablative treatment and bone marrow transplantation, with a regimen of methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B) as initial or salvage treatment for adults with diffuse large-cell lymphoma.

Malignancies associated with latent Epstein-Barr virus (EBV) are resistant to nucleoside-type antiviral agents because the viral enzyme target of these antiviral drugs, thymidine kinase (TK), is not expressed. Short-chain fatty acids, such as butyrate, induce EBV-TK expression in latently infected B cells. As butyrate has been shown to sensitize EBV+ lymphoma cells in vitro to apoptosis induced by ganciclovir, arginine butyrate in combination with ganciclovir was administered in 15 patients with refractory EBV+ lymphoid malignancies to evaluate the drug combination for toxicity, pharmacokinetics, and clinical responses. Ganciclovir was administered twice daily at standard doses, and arginine butyrate was administered by continuous infusion in an intrapatient dose escalation, from 500 mg/(kg/day) escalating to 2000 mg/(kg/day), as tolerated, for a 21-day cycle. The MTD for arginine butyrate in combination with ganciclovir was established as 1000 mg/(kg/day). Ten of 15 patients showed significant antitumor responses, with 4 CRs and 6 PRs within one treatment cycle. Complications from rapid tumor lysis occurred in 3 patients. Reversible somnolence or stupor occurred in 3 patients at arginine butyrate doses of greater than 1000 mg/(kg/day). The combination of arginine butyrate and ganciclovir was reasonably well-tolerated and appears to have significant biologic activity in vivo in EBV+ lymphoid malignancies which are refractory to other regimens.

Triple-negative breast cancers (TNBCs) are characterized by a poor prognosis and lack of targeted treatments, and thus, new therapeutic strategies are urgently needed. Inhibitors against programmed death-1 (PD-1)/PD-1 ligand (PD-L1) have shown significant efficacy in various solid cancers, but their activity against TNBCs remains limited. Here, we report that human TNBCs molecularly stratified for high levels of PD-L1 (PD-L1^High) showed significantly enriched expression of immune and cancer stemness pathways compared with those with low PD-L1 expression (PD-L1^Low). In addition, the PD-L1^High cases were significantly associated with a high stemness score (SS^High) signature. TNBC cell lines gated for aldehyde dehydrogenase (ALDH) and CD44 stemness markers exhibited increased levels of PD-L1 versus their ALDH-negative and CD44^Low counterparts, and PD-L1^High cells generated significantly more mammospheres than PD-L1^Low cells. Murine mammary SCA-1-positive tumor cells with PD-L1^High expression generated tumors in vivo with higher efficacy than PD-L1^Low cells. Furthermore, treatment of TNBC cells with selective WNT inhibitors or activators downregulated or upregulated PD-L1 expression, respectively, implying a functional cross-talk between WNT activity and PD-L1 expression. Remarkably, human TNBC samples contained tumor elements co-expressing PD-L1 with ALDH1A1 and/or CD44v6. Additionally, both PD-L1-/SCA1-positive and ALDH1A1-positive tumor elements were found in close contact with CD3-, and PD-1-positive T cells in murine and human tumor samples. Overall, our study suggests that PD-L1-positive tumor elements with a stemness phenotype may participate in the complex dynamics of TNBC-related immune evasion, which might be targeted through WNT signaling inhibition.

Mantle cell lymphoma (MCL) is rarely cured with standard-dose chemotherapy. From January 1997 to February 2000, 28 previously untreated advanced-stage MCL patients younger than 61 years of age were treated at 9 Italian hematologic departments with 3 cycles of standard-dose debulking chemotherapy followed by a high-dose rituximab-supplemented sequence (R-HDS) including intravenous administration of high-dose cyclophosphamide, high-dose cytarabine, high-dose melphalan, and high-dose mitoxantrone plus melphalan. Study end points included toxicity, clinical and molecular response rates, long-term event-free survival (EFS), and overall survival (OS) rates, as well as the ability to harvest tumor-free peripheral blood stem cells. Optimal amounts of polymerase chain reaction–negative (PCR-negative) CD34⁺ cells were collected from all 20 informative patients. One patient died of toxicity. All 27 patients assessable for response achieved a complete response (CR), of which 24 remain in continuous complete remission (CCR) after a median follow-up of 35 months. Three patients had transient evidence of PCR-detectable disease in the bone marrow. The OS and EFS rates at 54 months were 89% and 79%, respectively. These results compare with the 42% OS rate and the 18% EFS rate observed in 35 age-matched historic controls treated with standard-dose chemotherapy at the participating centers. The use of rituximab in combination with high-dose chemotherapy represents a very effective in vivo purging method. The R-HDS regimen can be safely applied in a multicenter hematology setting and leads to long-term EFS and OS in the majority of patients with an otherwise incurable disease.