Comprehensive Single-Cell Immune Profiling Defines the Patient Multiple Myeloma Microenvironment Following Oncolytic Virus Therapy in a Phase Ib Trial

PURPOSE

Our preclinical studies showed that the oncolytic reovirus formulation pelareorep (PELA) has significant immunomodulatory anti-myeloma activity. We conducted an investigator-initiated clinical trial to evaluate PELA in combination with dexamethasone (Dex) and bortezomib (BZ) and define the tumor immune microenvironment (TiME) in patients with multiple myeloma treated with this regimen.

PATIENTS AND METHODS

Patients with relapsed/refractory multiple myeloma (n = 14) were enrolled in a phase Ib clinical trial (ClinicalTrials.gov: NCT02514382) of three escalating PELA doses administered on Days 1, 2, 8, 9, 15, and 16. Patients received 40 mg Dex and 1.5 mg/m2 BZ on Days 1, 8, and 15. Cycles were repeated every 28 days. Pre- and posttreatment bone marrow specimens (IHC, n = 9; imaging mass cytometry, n = 6) and peripheral blood samples were collected for analysis (flow cytometry, n = 5; T-cell receptor clonality, n = 7; cytokine assay, n = 7).

RESULTS

PELA/BZ/Dex was well-tolerated in all patients. Treatment-emergent toxicities were transient, and no dose-limiting toxicities occurred. Six (55%) of 11 response-evaluable patients showed decreased paraprotein. Treatment increased T and natural killer cell activation, inflammatory cytokine release, and programmed death-ligand 1 expression in bone marrow. Compared with nonresponders, responders had higher reovirus protein levels, increased cytotoxic T-cell infiltration posttreatment, cytotoxic T cells in significantly closer proximity to multiple myeloma cells, and larger populations of a novel immune-primed multiple myeloma phenotype (CD138+ IDO1+HLA-ABCHigh), indicating immunomodulation.

CONCLUSIONS

PELA/BZ/Dex is well-tolerated and associated with anti-multiple myeloma activity in a subset of responding patients, characterized by immune reprogramming and TiME changes, warranting further investigation of PELA as an immunomodulator.

A Meta-analysis of Multiple Myeloma Risk Regions in African and European Ancestry Populations Identifies Putatively Functional Loci

BACKGROUND

Genome-wide association studies (GWAS) in European populations have identified genetic risk variants associated with multiple myeloma.

METHODS

We performed association testing of common variation in eight regions in 1,318 patients with multiple myeloma and 1,480 controls of European ancestry and 1,305 patients with multiple myeloma and 7,078 controls of African ancestry and conducted a meta-analysis to localize the signals, with epigenetic annotation used to predict functionality.

RESULTS

We found that variants in 7p15.3, 17p11.2, 22q13.1 were statistically significantly (P < 0.05) associated with multiple myeloma risk in persons of African ancestry and persons of European ancestry, and the variant in 3p22.1 was associated in European ancestry only. In a combined African ancestry-European ancestry meta-analysis, variation in five regions (2p23.3, 3p22.1, 7p15.3, 17p11.2, 22q13.1) was statistically significantly associated with multiple myeloma risk. In 3p22.1, the correlated variants clustered within the gene body of ULK4 Correlated variants in 7p15.3 clustered around an enhancer at the 3' end of the CDCA7L transcription termination site. A missense variant at 17p11.2 (rs34562254, Pro251Leu, OR, 1.32; P = 2.93 × 10-7) in TNFRSF13B encodes a lymphocyte-specific protein in the TNF receptor family that interacts with the NF-κB pathway. SNPs correlated with the index signal in 22q13.1 cluster around the promoter and enhancer regions of CBX7 CONCLUSIONS: We found that reported multiple myeloma susceptibility regions contain risk variants important across populations, supporting the use of multiple racial/ethnic groups with different underlying genetic architecture to enhance the localization and identification of putatively functional alleles.

IMPACT

A subset of reported risk loci for multiple myeloma has consistent effects across populations and is likely to be functional. Cancer Epidemiol Biomarkers Prev; 25(12); 1609-18. ©2016 AACR.

A phase 1, multicenter, open-label, dose escalation study of elotuzumab in patients with advanced multiple myeloma

This multicenter, first-in-human study evaluated the safety, tolerability, and pharmacokinetic and pharmacodynamic properties of the anti-CS1 monoclonal antibody elotuzumab. A standard 3 + 3 design was used to determine maximum tolerated dose; dose-limiting toxicities were assessed during cycle 1. Thirty-five patients with relapsed/refractory multiple myeloma were treated with intravenous elotuzumab at doses ranging from 0.5 to 20 mg/kg every 2 weeks. Patients who achieved at least stable disease after 4 treatments could receive another 4 treatments. No maximum tolerated dose was identified up to the maximum planned dose of 20 mg/kg. The most common adverse events, regardless of attribution, were cough, headache, back pain, fever, and chills. Adverse events were generally mild to moderate in severity, and adverse events attributed to study medication were primarily infusion-related. Plasma elotuzumab levels and terminal half-life increased with dose whereas clearance decreased, suggesting target-mediated clearance. CS1 on bone marrow-derived plasma cells was reliably saturated (≥ 95%) at the 10-mg/kg and 20-mg/kg dose levels. Using the European Group for Bone and Marrow Transplantation myeloma response criteria, 9 patients (26.5%) had stable disease. In summary, elotuzumab was generally well tolerated in this population, justifying further exploration of this agent in combination regimens.

Pharmacokinetic and pharmacodynamic study of two doses of bortezomib in patients with relapsed multiple myeloma

PURPOSE

Characterize bortezomib pharmacokinetics/pharmacodynamics in relapsed myeloma patients after single and repeat intravenous administration at two doses.

METHODS

Forty-two patients were randomized to receive bortezomib 1.0 or 1.3 mg/m(2), days 1, 4, 8, 11, for up to eight 21-day treatment cycles (n = 21, each dose group). Serial blood samples for pharmacokinetic/pharmacodynamic analysis were taken on days 1 and 11, cycles 1 and 3. Observational efficacy and safety data were collected.

RESULTS

Twelve patients in each dose group were evaluable for pharmacokinetics/pharmacodynamics. Plasma clearance decreased with repeat dosing (102-112 L/h for first dose; 15-32 L/h following repeat dosing), with associated increases in systemic exposure and terminal half-life. Systemic exposures of bortezomib were similar between dose groups considering the relatively narrow dose range and the observed pharmacokinetic variability, although there was no readily apparent deviation from dose-proportionality. Blood 20S proteasome inhibition profiles were similar between groups with mean maximum inhibition ranging from 70 to 84% and decreasing toward baseline over the dosing interval. Response rate (all 42 patients) was 50%, including 7% complete responses. The safety profile was consistent with the predictable and manageable profile previously established; data suggested milder toxicity in the 1.0 mg/m(2) group.

CONCLUSIONS

Bortezomib pharmacokinetics change with repeat dose administration, characterized by a reduction in plasma clearance and associated increase in systemic exposure. Bortezomib is pharmacodynamically active and tolerable at 1.0 and 1.3 mg/m(2) doses, with recovery toward baseline blood proteasome activity over the dosing interval following repeat dose administration, supporting the current clinical dosing regimen.

TRALI due to granulocyte-agglutinating human neutrophil antigen-3a (5b) alloantibodies in donor plasma: a report of 2 fatalities

BACKGROUND

TRALI is usually an immunologic reaction to WBC antibodies in infused plasma and ranks second only to ABO mismatch as a cause of transfusion-associated death. Implicated donors are usually multiparous women (>/=3 pregnancies).

STUDY DESIGN AND METHODS

Two fatal cases of TRALI were evaluated by reviewing clinical and laboratory findings and characterizing alloantibodies present in donor plasma. Investigation for WBC antibodies was by lymphocytotoxicity (LCT), FlowPRA (FlowPRA, One Lambda, Inc.) and granulocyte immunofluorescence and agglutination assays. Patient 1 was a 62-year-old man with chronic T-cell lymphocytic leukemia, and Patient 2 was a 54-year-old woman undergoing a cadaveric kidney transplant. Both patients developed acute respiratory distress and hypotension during (Patient 1) and approximately 30 minutes after (Patient 2) transfusion. Fulminant pulmonary edema ensued in both cases necessitating mechanical ventilation and both patients died within 24 hours of the onset of respiratory complications.

RESULTS

The donors of the implicated blood components were women with a history of two pregnancies but no blood transfusions. Weak apparently panreactive granulocyte antibodies were detected with flow cytometry. However, in the granulocyte agglutination test, strong antibodies specific for human neutrophil antigen (HNA)-3a (5b) were identified in both donors.

CONCLUSION

It is concluded that female blood donors with only two previous pregnancies can form clinically important granulocyte-reactive alloantibodies leading to fatal TRALI reactions in recipients. The sometimes devastating consequences of TRALI should prompt the development of strategies to prevent or reduce its incidence. Further research is warranted to investigate recipient and donor factors responsible for TRALI, including whether 5b (HNA-3a) alloantibodies are especially prone to cause severe reactions, and to better characterize the HNA-3a (5b) antigen, particularly at the molecular level.

Liposomal daunorubicin (DaunoXome) plus dexamethasone for patients with multiple myeloma. A phase II International Oncology Study Group study

BACKGROUND

Liposomal daunorubicin is an effective cytotoxic agent in patients with Kaposi sarcoma and hematologic malignancies. Anthracycline-based chemotherapy regimens, such as vincristine/doxorubicin/dexamethasone (VAD), are standard in the treatment of patients with multiple myeloma (MM). Cardiotoxicity remains a limiting factor in dose escalation of anthracyclines, and multidrug resistance (MDR) develops rapidly on exposure to anthracyclines. Liposomal daunorubicin was designed in an attempt to overcome MDR and to reduce anthracycline-related toxicities. Thus, an open-label, Phase II clinical study was conducted by the International Oncology Study Group to assess the efficacy and safety of intravenous liposomal daunorubicin at a dose of 100 mg/m2 given every 3 weeks for a maximum of 6 cycles in patients with recently diagnosed MM (n = 4 patients) or recurrent/refractory MM (n = 37 patients).

METHODS

Liposomal daunorubicin was administered as a single agent for the initial two cycles of therapy, and dexamethasone was added to all subsequent cycles. The primary study end point was response rates. Thirty-eight patients were treated, 35 of whom were evaluable for response.

RESULTS

A partial response was achieved in six patients (17%), including one patient with disease that previously was refractory to VAD therapy. Stable disease was observed in 22 patients (63%). The principal toxicity was myelosuppression. Grade 3 or 4 hematologic toxicities included granulocytopenia (26%), anemia (Grade 3 only; 11%), thrombocytopenia (11%), and febrile neutropenia (13%). The median survival in 35 patients with recurrent disease was 7.6 months.

CONCLUSIONS

Liposomal daunorubicin had activity in this population of poor-risk patients that was comparable to the activity of standard regimens. Further studies of this agent in combination with other anti-MM agents are warranted.

Quantitative measure of c-abl and p15 methylation in chronic myelogenous leukemia: biological implications

We used a sensitive, quantitative bisulfite PCR assay, methylation sensitive single nucleotide primer extension (Ms-SNuPE), to measure methylation of the 5' CpG islands of c-abl and p15 in chronic myelogenous leukemia (CML) patients during progression. We found that the Pa promoter of c-abl was methylated in 81% (17/21) of the white blood cells (WBCs) of CML patients, which correlates with previous reports. In contrast, WBCs from healthy donors, acute myelogenous leukemias, acute lymphocytic leukemias, and myelodysplastic syndromes were unmethylated at the c-abl Pa promoter locus. We also observed p15 hypermethylation in 24% (8/34) of CML cases. Methylation of the p15 but not c-abl Pa promoters was associated with CML progression (P = 0.047 vs 0.46), and the two events were independently acquired. We conclude that de novo methylation of c-abl and p15 both occur in CML, and analysis of DNA methylation changes using the bisulfite-based MS-SNuPE assay allows both a sensitive and quantitative assessment of these molecular events compared to other methods currently utilized. (Blood. 2000;95:2990-2992)

The influence of patient-related factors on ex vivo retroviral-mediated gene transfer into mobilized peripheral blood myeloid progenitors

Mobilized human peripheral blood progenitor cells are potential alternatives to bone marrow cells as targets for ex vivo gene transfer. We report the transduction efficiency of retroviral-mediated gene transfer into myeloid progenitors of peripheral blood progenitor cell (PBPC) harvests, mobilized by high-dose cyclophosphamide and GM-CSF, compared with nonmobilized bone marrow (BM). Eleven PBPC samples were enriched for CD34+ cells, preincubated with IL-3 (10 ng/ml), IL-6 (50 ng/ml), and 10% autologous plasma for 42 hr, and transduced over a 6-hr incubation with IL-3 + IL-6 and a retroviral vector carrying the NeoR gene. NeoR-specific sequences were detected by polymerase chain reaction in 10 cell pellets (91%). Gene expression in CFU-GM colonies was found in nine transduced samples (82%), with a mean transduction efficiency of 5.2% (95% CI, 1.3-11.8%) CFU-GM per PBPC sample. In univariate analysis, a higher transduction efficiency into CFU-GM correlated significantly with a higher CFU-GM concentration in the CD34+-enriched sample (p = 0.009), a shorter interval from diagnosis (p < 0.001), and fewer months of prior cytotoxic treatment (p = 0.001); correlation with younger age was of borderline statistical significance (p = 0.077). In multivariate analysis a shorter interval from diagnosis and, to a lesser degree, a higher CFU-GM concentration in the CD34+-enriched sample were independent predictors of higher transduction efficiency. Twelve BM samples were similarly transduced; 11 pellets were PCR positive. CFU-GM NeoR gene expression was 4.2% (95% CI, 2.0-7.2%) CFU-GM per BM sample, which was not significantly different from the transduction efficiency into PBPC cells. No correlation was found between the transduction efficiency of CFU-GM in BM samples and CFU-GM concentration in the CD34+-enriched sample, time from diagnosis, months of prior cytotoxic treatment, and/or patient age. Our data suggest that the transduction efficiency ex vivo may be influenced by time from diagnosis, CFU-GM concentration in the sample, and possibly by the extent of prior cytotoxic administration.

Adhesion of human myeloma-derived cell lines to bone marrow stromal cells stimulates interleukin-6 secretion

Previous studies show that human myeloma-derived cell lines specifically adhere to fibronectin (FN) through very late antigen-4 (VLA-4; alpha 4 beta 1 integrin complex) and RGD-peptide mechanisms, which may contribute to the localization of tumor cells in bone marrow (BM). In these studies, we characterized the adhesion of myeloma-derived cell lines to both normal and myeloma BM stromal cells (BMSCs) and the effect of adhesion on DNA synthesis. Because interleukin-6 (IL-6) plays an important role in the pathogenesis of multiple myeloma, we also examined the effects of tumor cell adhesion on IL-6 secretion by BMSCs. In 51chromium binding assays, the U266, ARH-77, and IM-9 cell lines showed 52% +/- 12%, 55% +/- 6%, and 47% +/- 7% specific adherence, respectively, to normal BMSCs and 74% +/- 4%, 60% +/- 3%, and 61% +/- 6% specific adherence, respectively, to myeloma BMSCs. In contrast, only 12% to 13% specific binding of HS-Sultan cells to BMSCs was noted. The binding of myeloma cells to BMSCs was partially blocked with anti-beta 1 monoclonal antibody (MoAb), anti-beta 2 integrin MoAb, and excess RGD peptide, suggesting multiple mechanisms for the adhesion of myeloma cell lines to BMSCs. Binding of cell lines to FN or myeloma BMSCs did not affect cell line proliferation; however, adhesion of myeloma cell lines to normal BMSCs decreased DNA synthesis, ie, stimulation indices are 0.1 +/- 0.04, 0.2 +/- 0.1, 0.2 +/- 0.07, and 0.1 +/- 0.06 for the adherent non-IL-6-dependent U266, ARH-77, HS-Sultan, and IM-9 cells, respectively (n = 5, P < .01). In contrast, adherence of IL-6-dependent B9 cells increased their proliferation (stimulation index, 3.2 +/- 0.7). Significant (twofold to eightfold) increases in IL-6 secretion were evident in cell line-adherent (> or = 12 hours) normal and myeloma BMSC cultures. Paraformaldehyde fixation of BMSCs before adhesion completely abrogated IL-6 secretion, suggesting that IL-6 secretion was triggered in BMSCs rather than in cell lines. Partial blocking of cell line adhesion to BMSCs, using anti-beta 1 integrin and anti-beta 2 integrin MoAbs and RGD peptide, also partially blocked the triggering of IL-6 secretion by BMSCs. When cell lines were placed in Transwell inserts and then cultured with either normal or myeloma BMSCs, permitting juxtaposition without cell to cell contact between myeloma cell lines and BMSCs, no increase in IL-6 secretion was observed.(ABSTRACT TRUNCATED AT 400 WORDS)