Advances in the molecular characterization of multiple myeloma and mechanism of therapeutic resistance

Recent insight in the genomic landscape of newly diagnosed multiple myeloma (NDMM) and its precursor conditions, monoclonal gammopathy of uncertain significance (MGUS), and smoldering myeloma have allowed the identification of patients with precursor conditions with a high risk of progression. These cases with "progressor" MGUS/SMM have a higher average mutation burden, have higher rates of mutations in specific genes such as MAPK, DNA repair, MYC, DIS3, and are enriched for specific mutational signatures when compared to non-progressors and are comparable to those found in NDMM. The highly preserved clonal heterogeneity seen upon progression of SMM, combined with the importance of these early variables, suggests that the identification of progressors based on these findings could complement and enhance the currently available clinical models based on tumor burden. Mechanisms leading to relapse/refractory multiple myeloma (RRMM) are of clinical interest given worse overall survival in this population. An Increased mutational burden is seen in patients with RRMM when compared to NDMM, however, there is evidence of branching evolution with many of these mutations being present at the subclonal level. Likewise, alterations in proteins associated with proteosome inhibitor and immunomodulatory drugs activity could partially explain clinical resistance to these agents. Evidence of chromosomal events leading to copy number changes is seen, with the presence of TP53 deletion, mutation, or a combination of both being present in many cases. Additional chromosomal events such as 1q gain and amplification may also interact and lead to resistance.

Carfilzomib and dexamethasone induction with lenalidomide, clarithromycin and dexamethasone consolidation and lenalidomide maintenance for newly diagnosed multiple myeloma

Combination treatment regimens including a proteasome inhibitor (PI), an immunomodulatory agent (IMiD) and a corticosteroid are standards of care for initial treatment of multiple myeloma (MM). We aimed to evaluate if a sequential treatment program using PI induction followed by IMiD based consolidation and maintenance could achieve similar outcomes with reduced toxicities. This phase 2 study was designed to assess the safety and efficacy of the Car-BiRd regimen: carfilzomib and dexamethasone (Kd) induction until maximum response, followed by lenalidomide, clarithromycin and dexamethasone (BiRd) consolidation until next maximum response, then lenalidomide maintenance in patients with newly diagnosed MM. Seventy-two patients, including both transplant eligible and ineligible patients, were enrolled and evaluated for response. The overall response rate to the Car-BiRd regimen was 94% with 83% of patients achieving a ≥ VGPR and 35% achieving a CR/sCR. The rate of CR/sCR increased from 7% with Kd induction to 21% with BiRd consolidation and 35% with lenalidomide maintenance. These results did not meet the study's target endpoint of a CR rate of 55%. The median PFS using this deferred transplant approach was 37.3 months (95% CI 27.9, 52.7) and median OS was not reached with a median follow-up of 60 months. Toxicities were primarily low grade and manageable. Hematologic toxicities were lower than those expected with a combination PI/IMiD protocol. The sequential Car-BiRd regimen is an effective and safe approach for the upfront treatment of MM including patients unfit for transplant.

Plasma Cell Myeloma Presenting With Amyloid-Laden Crystal-Negative Histiocytosis

OBJECTIVES

Crystal-storing histiocytosis (CSH) is rare in plasma cell dyscrasias, with only 3 cases reported in the setting of amyloid. No cases of crystal-negative histiocytosis coincident with multiple myeloma and amyloidosis have been reported previously.

METHODS

A 58-year-old woman presented with pain due to destructive bone lesions and was found to have plasma cell myeloma (PCM) and marrow amyloid deposition associated with crystal-negative histiocytosis. Differential diagnoses included Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai Dorfman disease. BRAF mutations were negative, and there was no evidence of paraprotein crystals, arguing against typical CSH.

RESULTS

The patient was treated with bortezomib, cyclophosphamide, and dexamethasone, and she subsequently underwent autologous stem cell transplant and ixazomib maintenance. She achieved complete remission with improvement of her symptoms and preserved remission after following up at 60 months.

CONCLUSIONS

We describe a case of crystal-negative histiocytosis associated with PCM. CSH is a rare disorder associated with paraprotein-producing conditions in which immunoglobulins aggregate as intracellular crystals in the lysosomes of organ-specific phagocytic macrophages. Light chain tropism in PCM can also lead to the development of amyloid deposition in organs and, in rare cases, is associated with light chain aggregation as intracellular crystals in macrophages.

COVID-19 Infections and Clinical Outcomes in Patients with Multiple Myeloma in New York City: A Cohort Study from Five Academic Centers

Patients with multiple myeloma have a compromised immune system, due to both the disease and antimyeloma therapies, and may therefore be particularly susceptible to COVID-19. Here, we report outcomes and risk factors for serious disease in patients with multiple myeloma treated at five large academic centers in New York City in the spring of 2020, during which it was a global epicenter of the SARS-CoV-2 pandemic. Of 100 patients with multiple myeloma (male 58%; median age 68) diagnosed with COVID-19, 75 were admitted; of these, 13 patients (17%) were placed on invasive mechanical ventilation, and 22 patients (29%) expired. Of the 25 nonadmitted patients, 4 were asymptomatic. There was a higher risk of adverse outcome (intensive care unit admission, mechanical ventilation, or death) in Hispanics/Latinos (n = 21), OR = 4.7 (95% confidence interval, 1.3-16.7), and African American Blacks (n = 33), OR = 3.5 (1.1-11.5), as compared with White patients (n = 36). Patients who met the adverse combined endpoint had overall higher levels of inflammatory markers and cytokine activation. None of the other studied risk factors were significantly associated (P > 0.05) with adverse outcome: hypertension (n = 56), OR = 2.2 (0.9-5.4); diabetes (n = 18), OR = 0.9 (0.3-2.9); age >65 years (n = 63), OR = 1.8 (0.7-4.6); high-dose melphalan with autologous stem cell transplant <12 months (n = 7), OR = 0.9 (0.2-5.4); and immunoglobulin G <650 mg/dL (n = 42), OR = 0.9 (0.3-2.2). In this largest cohort to date of patients with multiple myeloma and COVID-19, we found the case fatality rate to be 29% among hospitalized patients and that race/ethnicity was the most significant risk factor for adverse outcome.

Significance

Patients with multiple myeloma are immunocompromised, raising the question whether they are at higher risk of severe COVID-19 disease. In this large case series on COVID-19 in patients with multiple myeloma, we report 29% mortality rates among hospitalized patients and identify race/ethnicity as the most significant risk factor for severe outcome.See related commentary by Munshi and Anderson, p. 218. This article is highlighted in the In This Issue feature, p. 215.

COVID-19 infections and outcomes in patients with multiple myeloma in New York City: a cohort study from five academic centers

Importance

New York City is a global epicenter for the SARS-CoV-2 outbreak with a significant number of individuals infected by the virus. Patients with multiple myeloma have a compromised immune system, due to both the disease and anti-myeloma therapies, and may therefore be particularly susceptible to coronavirus disease 2019 (COVID-19); however, there is limited information to guide clinical management.

Objective

To assess risk factors and outcomes of COVID-19 in patients with multiple myeloma.

Design

Case-series.

Setting

Five large academic centers in New York City.

Participants

Patients with multiple myeloma and related plasma cell disorders who were diagnosed with COVID-19 between March 10th, 2020 and April 30th, 2020.

Exposures

Clinical features and risk factors were analyzed in relation to severity of COVID-19.

Main Outcomes and Measures

Descriptive statistics as well as logistic regression were used to estimate disease severity reflected in hospital admissions, intensive care unit (ICU) admission, need for mechanical ventilation, or death.

Results

Of 100 multiple myeloma patients (male 58%; median age 68, range 41-91) diagnosed with COVID-19, 74 (74%) were admitted; of these 13 (18%) patients were placed on mechanical ventilation, and 18 patients (24%) expired. None of the studied risk factors were significantly associated (P>0.05) with adverse outcomes (ICU-admission, mechanical ventilation, or death): hypertension (N=56) odds ratio (OR) 2.3 (95% confidence interval [CI] 0.9-5.9); diabetes (N=18) OR 1.1 (95% CI 0.3-3.2); age >65 years (N=63) OR 2.0 (95% CI 0.8-5.3); high dose melphalan with autologous stem cell transplant <12 months (N=7) OR 1.2 (95% CI 0.2-7.4), IgG<650 mg/dL (N=42) OR=1.2 (95% CI 0.4-3.1). In the entire series of 127 patients with plasma cell disorders, hypertension was significantly associated with the combined end-point (OR 3.4, 95% CI 1.5-8.1).

Conclusions and Relevance

Although multiple myeloma patients have a compromised immune system due to both the disease and therapy; in this largest disease specific cohort to date of patients with multiple myeloma and COVID-19, compared to the general population, we found risk factors for adverse outcome to be shared and mortality rates to be within the higher range of officially reported mortality rates.

High-dose bendamustine and melphalan conditioning for autologous stem cell transplantation for patients with multiple myeloma

High-dose melphalan (MEL200) followed by autologous stem cell transplantation (ASCT) remains a standard of care for multiple myeloma (MM). Bendamustine induces responses in MM resistant to other alkylators. Our prior Phase I trial adding bendamustine to MEL200 transplant conditioning resulted in no additional toxicity. We now report a single-arm, phase II study that evaluated the efficacy of bendamustine 225 mg/m² with MEL200 conditioning for ASCT in 18 patients with newly diagnosed MM (NDMM) and 17 with relapsed or refractory MM (RRMM). The primary end point was the complete response (CR/sCR) rate at day+ 100. Sample size was determined according to Simon's two-stage design. At stage 1, sixteen patients entered the study. As there were eight patients with CR/sCR, enrollment increased to 28 patients. Sixteen out of the first 28 evaluable patients achieved CR/sCR, meeting the design criteria. Enrollment was then expanded to a total of 35 patients. 51% achieved a CR/sCR. After a median follow-up of 65 months, 21 patients progressed, including 7 deaths. The median PFS for NDMM and RRMM was 48 and 45 months, respectively. Bendamustine/MEL200 conditioning resulted in excellent overall and depth of response as well as PFS, particularly in the RRMM patients, and is worthy of further investigation (NCT00916058).

Phase II study of carfilzomib and dexamethasone therapy for newly diagnosed multiple myeloma

Carfilzomib and dexamethasone (Kd) has significant activity in relapsed and refractory multiple myeloma. Kd has not previously been evaluated in newly diagnosed multiple myeloma (NDMM). We report a single-arm phase 2 study of 72 patients with NDMM to evaluate the efficacy and tolerability of Kd induction. Carfilzomib was administered in two dosing cohorts with dosing of 20/45 mg/m² in the first 25 patients and 20/56 mg/m² in the subsequent 47 patients. Carfilzomib was administered on days 1, 2, 8, 9, 15 and 16 of a 28-day cycle, dexamethasone 20 mg was administered orally on days 1, 2, 8, 9, 15, 16, 22 and 23. Treatment was continued to maximum response, progression of disease, or regimen intolerability. Endpoints included overall response rate (ORR), regimen toxicity and impact of carfilzomib on CD34+ stem cell collection yield. Sixty-five pts achieved at least a partial response (PR) for an ORR of 90%. The maximum response achieved was complete response or better in 5 (7%), very good partial response (VGPR) in 42 (58%), PR in 18 (25%) and stable disease in 7 pts (10%). Toxicities were predominantly low grade with 547 grade 1/2 adverse events and 44 grade ≥3 events. The rate of grade ≥3 cardiovascular adverse events was 11.1% with eight observed events. The activity of Kd described represents the highest rate of overall response and ≥VGPR for any 2-agent combination in NDMM reported to date. Kd demonstrated a safety profile consistent with previously reported carfilzomib studies.

Comparison of time to engraftment between autologous patients receiving washed versus non-washed cryopreserved peripheral blood stem cell products

Washing cryopreserved peripheral blood stem cell (PBSC) products can decrease infusion-related adverse reactions but can also result in cell loss and reduced cell viability. To assess the risk and benefit of washing products, we compared the time to neutrophil and platelet engraftment between autologous patients that received washed products (n = 201) and non-washed products (n = 89). The effect of the other variables, including age, gender, diagnosis, transplant dose, method of stem cell mobilization, and growth factor support regimen post-transplant, was assessed. In multivariate analysis, direct thaw and infusion of non-washed products resulted in significantly faster neutrophil engraftment (p = .003) and platelet engraftment (p = .017) than washed products. The mean neutrophil and platelet engraftment times were 1.07 days faster and 2.27 days faster, respectively. In conclusion, direct thaw and infusion of cryopreserved PBSC without washing results in significantly shorter time to recovery of neutrophils and platelets after autologous transplantation.

Thalidomide, clarithromycin, lenalidomide and dexamethasone therapy in newly diagnosed, symptomatic multiple myeloma

We studied T-BiRD (thalidomide [Thalomid(®)], clarithromycin [Biaxin(®)], lenalidomide [Revlimid(®)] and dexamethasone) in symptomatic, newly diagnosed multiple myeloma. In 28-day cycles, patients received dexamethasone 40 mg/day on days 1, 8, 15, 22, clarithromycin 500 mg twice daily on days 1-28; lenalidomide 25 mg/day on days 1-21; and thalidomide 100 mg/day (50 mg/day on days 1-7 of cycle 1 only) on days 1-28. Twenty-six patients received a median of 6 cycles (range 0-41). Overall response rate (ORR) was 80% for the group and 100% in 11 patients who underwent autologous stem cell transplantation as part of first-line therapy. The 4-year overall survival rate was 74.9%, and the median progression-free survival was 35.6 months. Eight patients discontinued due to regimen toxicity. Grade 3 non hematologic toxicity affected 12 patients (46.2%). T-BiRD is a highly active regimen with potential toxicity limitations. ClinicalTrials.gov identifier: NCT00538733.

Age matters: Young T lymphocytes offer better protection from myeloma proliferation

BACKGROUND

The incidence and growth of cancer has been reported to increase with age and/or impaired T lymphocyte function.

RESULTS

Consistent with these observations, we found that a monoclonal serum immunoglobulin (mIgG2b), rarely detectable after the injection of 5T33 murine multiple myeloma (MMM) cells into 3-4 month old wild-type C57BL/6 mice was seen more frequently in 18-20 month old wild-type C57BL/6 mice and in 3-4 month old Rag1-deficient C57BL/6 mice. These observations were confirmed and extended using more sensitive assays such as quantitation of splenic mRNA specific for the canonical 5T33 monoclonal IgG2b produced by 5T33 myeloma cells and the most sensitive assay, photon-imaging of mice injected with 5T33 cells, stably transfected with fire-fly luciferase gene (5T33L cells), which emit photons after the injection of luciferin. Furthermore, the proliferation of 5T33L myeloma cells in Rag1-deficient C57BL/6 mice was greater in mice which also received spleen T cells from 18-20 month old C57BL/6 wild-type mice compared to mice which received splenic T cells from 3-4 month old C57BL/6 wild-type mice. Thus, immune reconstitution of C57BL/6 mice with splenic T cells from young wild-type mice offered greater protection from progressive growth of 5T33L myeloma cells than did reconstitution with splenic T cells from old mice.

CONCLUSIONS

Our findings support the hypothesis that age-associated changes in splenic T cell function contribute to the increased growth of 5T33 MMM cells in old compared to young C57BL/6 mice. Should similar processes occur in humans, increasing the anti-myeloma activity of T cells in old patients with multiple myeloma or transferring cryopreserved, young, autologous, T cells might benefit elderly patients with multiple myeloma.

Overcoming the response plateau in multiple myeloma: a novel bortezomib-based strategy for secondary induction and high-yield CD34+ stem cell mobilization

PURPOSE

This phase II study evaluated bortezomib-based secondary induction and stem cell mobilization in 38 transplant-eligible patients with myeloma who had an incomplete and stalled response to, or had relapsed after, previous immunomodulatory drug-based induction.

EXPERIMENTAL DESIGN

Patients received up to six 21-day cycles of bortezomib plus dexamethasone, with added liposomal doxorubicin for patients not achieving partial response or better by cycle 2 or very good partial response or better (≥VGPR) by cycle 4 (DoVeD), followed by bortezomib, high-dose cyclophosphamide, and filgrastim mobilization. Gene expression/signaling pathway analyses were conducted in purified CD34+ cells after bortezomib-based mobilization and compared against patients who received only filgrastim ± cyclophosphamide. Plasma samples were similarly analyzed for quantification of associated protein markers.

RESULTS

The response rate to DoVeD relative to the pre-DoVeD baseline was 61%, including 39% ≥ VGPR. Deeper responses were achieved in 10 of 27 patients who received bortezomib-based mobilization; postmobilization response rate was 96%, including 48% ≥ VGPR, relative to the pre-DoVeD baseline. Median CD34+ cell yield was 23.2 × 10(6) cells/kg (median of 1 apheresis session). After a median follow-up of 46.6 months, median progression-free survival was 47.1 months from DoVeD initiation; 5-year overall survival rate was 76.4%. Grade ≥ 3 adverse events included thrombocytopenia (13%), hand-foot syndrome (11%), peripheral neuropathy (8%), and neutropenia (5%). Bortezomib-based mobilization was associated with modulated expression of genes involved in stem cell migration.

CONCLUSION

Bortezomib-based secondary induction and mobilization could represent an alternative strategy for elimination of tumor burden in immunomodulatory drug-resistant patients that does not impact stem cell yield.

Clarithromycin, pomalidomide, and dexamethasone (ClaPD) in relapsed or refractory multiple myeloma

8036

Background: Clarithromycin has been shown to enhance anti-myeloma activity of lenalidomide+dexamethasone in the upfront treatment of multiple myeloma (MM). Pomalidomide is an immunomodulatory agent effective in relapsed/refractory MM (RRMM). We hypothesized that clarithromycin may similarly enhance pomalidomide + dexamethasone in RRMM. We now report updated results from a phase 2 trial of ClaPD in RRMM. Methods: 73 patients with RRMM were enrolled in a single-institution phase 2 study of ClaPD. All subjects had ≥ 3 prior lines of therapy, one of which must have included lenalidomide. ClaPD is clarithromycin 500mg twice daily; dexamethasone 40mg weekly; and pomalidomide 4mg for days 1-21 of a 28-day cycle. All patients had VTE prophylaxis with aspirin. Monthly disease response evaluation included immunoelectrophoresis and free light chain analysis; bone marrow biopsy with skeletal imaging was used to confirm MM responses. Treatment continued as tolerated until disease progression. Results: The 66 patients who completed ≥ 1 cycle of ClaPD are reported. Median number of cycles was 6 (range 1-17). Responses were progressive disease: 10%, stable disease: 21%, minimal response: 12%, partial response: 33%, very good partial response: 18%, stringent complete remission: 5%, for an overall response rate (ORR) of 56% and ≥VGPR rate of 23%. Median time to PR was 1.25 cycles (range 1-8). Median PFS was 5 months. Response and PFS were not different in patients refractory to lenalidomide (85%), bortezomib (82%), or double-refractory patients (76%). After a median follow up of 12 months,28 pts (42%) remain on study without progression and 56pts (85%) are alive. Two pts withdrew due to toxicity (1 Grade 3 fatigue, 1 Grade 4 muscular weakness). One patient withdrew consent. Conclusions: ClaPD is highly effective for heavily pre-treated RRMM, particularly in lenalidomide-refractory disesase and compares favorably to previously published Phase 2 data of Pom/Dex (ORR 56% vs 40% - Lacy et. al JCO 2009) without excess toxicity. Response to ClaPD is rapid, well tolerated, and sustained over 7 months in most subjects. These data support the clinical efficacy of pomalidomide based regimens in RRMM.

Atypical serum immunofixation patterns frequently emerge in immunomodulatory therapy and are associated with a high degree of response in multiple myeloma

The M-protein is the major reference measure for response in multiple myeloma (MM) and its correct interpretation is key to clinical management. The emergence of oligoclonal banding is recognized as a benign finding in the postautologous stem cell transplantation setting (ASCT) for MM but its significance during non-myeloablative therapy is unknown. In a study of the immunomodulatory combination BiRD, (lenalidomide and dexamethasone with clarithromycin), we frequently detected the emergence of mono- and oligo-clonal immunoglobulins unrelated to the baseline diagnostic M-protein. The new M-proteins seen on serum immunofixation electrophoresis were clearly different in either heavy or light chain component(s) from the original M-spike protein and were termed atypical serum immunofixation patterns (ASIPs). Overall, 24/72 (33%) patients treated with BiRD developed ASIPs. Patients who developed ASIPs compared with patients treated with BiRD without ASIPs, had a significantly greater overall response (100% vs. 85%) and complete response rates (71% vs. 23%). ASIPs were not associated with new clonal plasma cells or other lymphoproliferative processes, and molecular remissions were documented. This is the first time this phenomenon has been seen with regularity in non-myeloablative therapy for MM. Analogous to the ASCT experience, ASIPs do not signal incipient disease progression, but rather herald robust response.

Stem cell mobilization with cyclophosphamide overcomes the suppressive effect of lenalidomide therapy on stem cell collection in multiple myeloma

A total of 28 treatment-naïve patients with stage II or III multiple myeloma (MM) were treated with the combination of clarithromycin, lenalidomide, and dexamethasone (BiRD). Stem cells were collected following granulocyte-colony stimulating factor (G-CSF) or cyclophosphamide (Cy) plus G-CSF mobilization at maximum response. Sufficient stem cells for 2 autologous stem cell transplants were collected from all patients mobilized with Cy plus G-CSF, versus 33% mobilized with G-CSF alone (P < .0001). The duration of prior lenalidomide therapy did not correlate with success of stem cell harvests (P = .91). In conclusion, Cy can be added to G-CSF for stem cell mobilization to successfully overcome the suppressive effect of prior treatment with lenalidomide.

New strategies for the treatment of metastatic bone disease

The introduction of bisphosphonates represents an important advance in the care of patients with metastatic bone disease. Nonetheless, we remain unable to prevent metastatic bone destruction. This review will discuss several novel therapies, including inhibitors of receptor activator of nuclear factor-kappabeta, c-Src, mammalian target of rapamycin, cathepsin K, and alpha(5)beta(3) integrins, which could improve our control over this devastating complication.

Lenalidomide-induced myelosuppression is associated with renal dysfunction: adverse events evaluation of treatment-naïve patients undergoing front-line lenalidomide and dexamethasone therapy

Data on 72 patients receiving lenalidomide/dexamethasone for multiple myeloma (MM) was used to determine the factors that are associated with lenalidomide-induced myelosuppression. Eight of 14 patients with grade > or =3 myelosuppression had baseline creatinine clearance (CrCl) < or =0.67 ml/s. Kaplan-Meier analysis by log-rank test demonstrated a significant association (P < 0.0001) between renal insufficiency and time to myelosuppression (hazard ratio = 8.4; 95% confidence interval 2.9-24.7, P = 0.0001). Therefore, CrCl is inversely associated with significant myelosuppression. Caution should be exercised when lenalidomide therapy is commenced and CrCl should be incorporated as a determinant of the initial dosing of lenalidomide in MM patients.

Advances in treating metastatic bone cancer: summary statement for the First Cambridge Conference

The First Cambridge Conference on Advances in Treating Metastatic Bone Cancer, a symposium held in Cambridge, Massachusetts, October 28 to 29, 2005, was convened to discuss recent advances and research related to the natural history of bone metastases and skeletal complications, bone cancer biology, treatment of myeloma and other solid tumors, and treatment-induced bone loss. The conference format combined brief presentations with extended periods of discussion. The conclusions reached during the 2-day meeting are summarized in this article and presented in more detail in the individual articles and accompanying discussion sessions that comprise the conference proceedings.

Wnt antagonism in multiple myeloma: a potential cause of uncoupled bone remodeling

Bone disease in patients with multiple myeloma (MM) is characterized by uncoupled bone remodeling, evident as enhanced osteolytic resorption and decreased rather than increased bone formation. MM-triggered osteolysis follows deregulation of the receptor activator of nuclear factor kappaB ligand (RANKL)/osteoprotegerin cytokine axis. Inhibition of bone formation may result from the ability of MM to inhibit the function of Wnts, secreted glycoproteins critical to osteoblast development. Recent studies show how these processes may be linked.

A neurotrophin axis in myeloma: TrkB and BDNF promote tumor-cell survival

Multiple myeloma (MM) is a B-cell neoplasm that is characterized by the clonal expansion of malignant plasma cells and is frequently associated with chromosomal translocations placing an oncogene under the control of the immunoglobulin heavy chain enhancer. Despite these pathogenic translocations, MM cells remain dependent on external cues for survival. We present evidence that brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family of growth factors, and its high-affinity receptor, tropomyosin receptor kinase B (TrkB), contribute to these survival cues. MM cells express TrkB, and respond to BDNF by activating mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase-a PI3K target (PI3K/Akt) signaling cascades. Addition of BDNF protects human MM cell lines (HMCLs) from apoptosis induced by dexamethasone or bortezomib and prolongs the survival of primary MM cells cultured alone or with human bone marrow (BM) stroma. As BDNF and TrkB are expressed by osteoblasts, stromal cells, and endothelial cells within the BM microenvironment, a BDNF-TrkB axis may be critical to the interactions of MM with bone and stroma that contribute to MM tumor progression. Finally, BDNF is expressed by malignant plasma cells isolated from a subset of patients with MM, as well as by most HMCLs, suggesting a potential role for this neurotrophin axis in autocrine as well as paracrine support of MM.

Myeloma interacts with the bone marrow microenvironment to induce osteoclastogenesis and is dependent on osteoclast activity

Myeloma tumour growth, except in the most advanced stages of the disease, is restricted to the bone marrow. We used the severe combined immunodeficient-human (SCID-hu) host system, in which primary human myeloma cells grow in, disseminate to and interact with a human microenvironment, to study the interactions between myeloma cells and cells in the bone marrow microenvironment. We used inhibitors of osteoclast activity to determine the role of osteoclasts and their products in supporting myeloma cell growth. Treatment of myelomatous SCID-hu hosts with an inhibitor of osteoclast activity (pamidronate or zoledronate) or with a specific inhibitor of the receptor activator of NF-kappaB ligand (RANKL) halted myeloma-induced bone resorption, when present, and resulted in inhibition of myeloma cell growth and survival. In contrast, myeloma cells from patients with extramedullary disease had a different growth pattern in the SCID-hu hosts and were not inhibited by these interventions, indicating that, while still dependent on a human microenvironment, these cells no longer required the bone marrow microenvironment for survival. This study demonstrates the dependence of myeloma cells on osteoclast activity and their products, and highlights the importance of the myeloma-osteoclast-myeloma loop for sustaining the disease process. Breaking this loop may help control myeloma.

Multiple myeloma disrupts the TRANCE/ osteoprotegerin cytokine axis to trigger bone destruction and promote tumor progression

Bone destruction, caused by aberrant production and activation of osteoclasts, is a prominent feature of multiple myeloma. We demonstrate that myeloma stimulates osteoclastogenesis by triggering a coordinated increase in the tumor necrosis factor-related activation-induced cytokine (TRANCE) and decrease in its decoy receptor, osteoprotegerin (OPG). Immunohistochemistry and in situ hybridization studies of bone marrow specimens indicate that in vivo, deregulation of the TRANCE-OPG cytokine axis occurs in myeloma, but not in the limited plasma cell disorder monoclonal gammopathy of unknown significance or in nonmyeloma hematologic malignancies. In coculture, myeloma cell lines stimulate expression of TRANCE and inhibit expression of OPG by stromal cells. Osteoclastogenesis, the functional consequence of increased TRANCE expression, is counteracted by addition of a recombinant TRANCE inhibitor, RANK-Fc, to marrow/myeloma cocultures. Myeloma-stroma interaction also has been postulated to support progression of the malignant clone. In the SCID-hu murine model of human myeloma, administration of RANK-Fc both prevents myeloma-induced bone destruction and interferes with myeloma progression. Our data identify TRANCE and OPG as key cytokines whose deregulation promotes bone destruction and supports myeloma growth.

SHIP recruitment attenuates Fc gamma RIIB-induced B cell apoptosis

Fc gammaRIIB is an inhibitory receptor that terminates activation signals initiated by antigen cross-linking of the BCR through the recruitment of SHIP. Fc gammaRIIB can also signal independently of BCR coligation to directly mediate an apoptotic response, requiring only an intact transmembrane domain. Failure to recruit SHIP, either by deletion of SHIP or mutation of Fc gammaRIIB, results in enhanced Fc gammaRIIB-triggered apoptosis. Thus, in the germinal center, where ICs are retained by FDCs, Fc gammaRIIB may be an active determinant in the negative selection of B cells whose BCRs have reduced affinity for antigen as a result of somatic hypermutation. Selection of B cells may represent the sum of opposing signals generated by the interaction of ICs with the BCR and Fc gammaRIIB through pathways modulated by SHIP.

SHIP modulates immune receptor responses by regulating membrane association of Btk

Membrane recruitment of SHIP is responsible for the inhibitory signal generated by FcgammaRIIB coligation to the BCR. By reducing the level of PIP3, SHIP regulates the association of the tyrosine kinase Btk with the membrane through PH domain-phosphoinositol lipid interactions. Inhibition of BCR signaling by either FcgammaRIIB coligation, membrane expression of SHIP, or inhibition of P13K, conditions which result in decreased levels of PIP3, is suppressed by the expression of Btk as a membrane-associated chimera. Conversely, increasing PIP3 levels by deletion of SHIP results in increased Btk association with the membrane and hyperresponsive BCR signaling. These results suggest a central role for PIP3 in regulating the B cell stimulatory state by modulating Btk localization and thereby calcium fluxes.

Infectious complications of autologous bone marrow and peripheral stem cell transplantation for refractory leukemia and lymphoma

We aimed to characterize the infectious complications of autologous bone marrow (AuBMT) and peripheral stem cell transplantation (PSCT) in patients with refractory leukemia and lymphoma. We performed a retrospective analysis of all patients (n = 56) with refractory leukemia or lymphoma treated with AuBMT or PSCT at Memorial Sloan-Kettering Cancer Center from January 1993 to July 1994. Records were available in 55, of whom 33 (60%) received AuBMT and 22 (40%) PSCT. Fifteen (27%) developed complicated infections, including 13 (39%) treated with AuBMT and two (9%) with PSCT. Complicated infections were caused by bacterial (11 episodes), fungal (four episodes), and viral (four episodes) pathogens. Five (9%) infections were fatal. In a multivariate model, only duration of neutropenia was significantly associated with development of complicated infection (P = 0.006). Thus, 27% of patients with refractory leukemia or lymphoma treated with AuBMT or PSCT developed complicated infections and 9% died of infection. Prolonged neutropenia was significantly associated with development of infection. Patients receiving PSCT had significantly lower rates of complicated infection, presumably due to the associated shorter duration of neutropenia. Future studies are needed to define the role of PSCT as treatment for refractory neoplastic disease.

PU.1 and an HLH family member contribute to the myeloid-specific transcription of the Fc gamma RIIIA promoter

Expression of the low-affinity Fc receptor for IgG (murine Fc gamma RIIIA) is restricted to cells of myelomonocytic origin. We report here the promoter structure, the proximal DNA sequences responsible for transcription of Fc gamma RIIIA in macrophages and the protein factors which interact with these sequences. A 51 bp sequence, termed the myeloid restricted region (MRR), was both necessary and sufficient for conferring cell type-specific expression in macrophages. Reporter constructs containing mutations in this sequence result in the loss of MRR activity upon transfection into the macrophage cell line, RAW264.7. Two cis-acting elements have been identified and are required for full promoter function. These same elements analyzed by EMSA define two binding sites recognized by nuclear factors derived from macrophages. A 3' purine tract (-50 to -39) within the MRR binds the macrophage and B cell-specific factor, PU.1, and a second E box-like element, termed MyE, upstream of the PU.1 box (-88 to -78) binds the HLH factors TFE3 and USF. EMSA studies using RAW cell extracts suggest that both PU.1 and MyE factors may bind simultaneously to the MRR resulting in a ternary complex that is responsible, in part, for the myeloid-specific activity of the Fc gamma RIIIA promoter.

Interferon gamma-induced transcription of the high-affinity Fc receptor for IgG requires assembly of a complex that includes the 91-kDa subunit of transcription factor ISGF3

A 39-nt DNA sequence, the interferon gamma (IFN-gamma) response region (GRR), is necessary for the IFN-gamma-induced transcription of the high-affinity Fc receptor for IgG (Fc gamma RI) and sufficient for the IFN-gamma-induced transcription of transfected plasmids. By using extracts from IFN-gamma-treated cells, three protein complexes will assemble in vitro on a 9-nt core region in the 3' domain of the GRR. The sequence of this core resembles the IFN-gamma-activated sequence (GAS) described for the GBP gene. Mutations in this GAS core region prevent complex assembly and result in the loss of IFN-gamma induction of reporter constructs containing the mutation. In addition to the GAS core region, a 5' region of the GRR is necessary for optimal IFN-gamma induction and for formation of one of the DNA-protein complexes. By antibody reactivity, we show that a 91-kDa protein, first identified as a component of ISGF3, the IFN-alpha-induced transcription complex, is present in at least two of the DNA-protein complexes. IFN-alpha can induce the formation of the faster-migrating 91-kDa protein-GAS complex but not the slower-migrating complex. Furthermore, IFN-alpha does not result in appreciable transcriptional activation of Fc gamma RI or constructs containing the GRR. Thus, these data demonstrate that the IFN-gamma-activated 91-kDa protein is required for IFN-gamma induction of Fc gamma RI and suggest that an additional complex may be required for optimal expression and specificity.

Characterization of the promoter of the human gene encoding the high-affinity IgG receptor: transcriptional induction by gamma-interferon is mediated through common DNA response elements

Expression of the high-affinity receptor for IgG (Fc gamma RI) is restricted to cells of myeloid lineage and is induced by gamma-interferon (IFN-gamma) but not by IFN-alpha/beta. The organization of the human Fc gamma RI gene has been determined and the DNA elements governing its cell type-restricted transcription and IFN-gamma induction are reported here. A 39-nucleotide sequence (IFN-gamma response region, or GRR) is defined that is both necessary and sufficient for IFN-gamma inducibility. Sequence analysis of the GRR reveals the presence of promoter elements initially defined for the major histocompatibility complex class II genes: i.e., X, H, and gamma-IRE sequences. Comparison of a number of genes whose expression is induced selectively by IFN-gamma indicates that the presence of these elements is a general feature of IFN-gamma-responsive genes. Our studies suggest that the combination of X, H, and gamma-IRE elements is a common motif in the pathway of transcriptional induction by this lymphokine.

The noradrenergic system in cultured aggregates of fetal rat brain cells: morphology of the aggregates and pharmacological indices of noradrenergic neurons

Spherical aggregates formed rapidly in culture by re-aggregation of trypsin-dissociated brain cells from the 17-day-old fetal rat. Over about 10 days in initially random distribution of cells evolved into a 3-layered arrangement; cells with characteristics of neurons were found largely in the intermediate layer. The survival of neuronal and glial cell types was evaluated histologically and verified by electron microscopy, which revealed synaptic and myelin structures that rapidly increased in number after 18 days in culture. Levels of norepinephrine (NE) and dopamine (DA) reached peaks of 9.5 and 4.4 ng/mg protein, respectively, at culture day 21. Uptake of [3H]NE paralleled these amine levels and was blocked by desipramine or pretreatment with either reserpine or 6-OH-DA. Autoradiographs of aggregates labeled with [3H]NE showed a high density of silver grains over cells, apparently neurons, with branching processes traced for 120 micrometer. Previously accumulated [3H]NE was released under depolarizing conditions (high [K+] or vertridine) only in the presence of Ca2+. Release was induced to a lesser extent by kainic greater than glutamic acid. Thus, such aggregates appear to contain catecholaminergic neurons capable of synthesis, uptake and release of NE. The time course of development of these functions supports suggestions that aggregate preparations might be useful in studying neurochemical or morphological aspects of brain development and function in vitro.