Development of aggressive plasma cell leukaemia under interferon-alpha therapy

Plasma cell leukemia: consensus statement on diagnostic requirements, response criteria and treatment recommendations by the International Myeloma Working Group

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma characterized by the presence of circulating plasma cells. It is classified as either primary PCL occurring at diagnosis or as secondary PCL in patients with relapsed/refractory myeloma. Primary PCL is a distinct clinic-pathological entity with different cytogenetic and molecular findings. The clinical course is aggressive with short remissions and survival duration. The diagnosis is based upon the percentage (≥ 20%) and absolute number (≥ 2 × 10(9)/l) of plasma cells in the peripheral blood. It is proposed that the thresholds for diagnosis be re-examined and consensus recommendations are made for diagnosis, as well as, response and progression criteria. Induction therapy needs to begin promptly and have high clinical activity leading to rapid disease control in an effort to minimize the risk of early death. Intensive chemotherapy regimens and bortezomib-based regimens are recommended followed by high-dose therapy with autologous stem cell transplantation if feasible. Allogeneic transplantation can be considered in younger patients. Prospective multicenter studies are required to provide revised definitions and better understanding of the pathogenesis of PCL.

Effects of native human leukocyte interferon-alpha and recombinant human interferon-alpha on P3-X63-Ag8.653 mouse myeloma cell growth

Multiple myeloma (MM) remains largely incurable, although traditional chemotherapy and new compounds have been shown to produce a clinical response. Clinical studies were performed to determine the effectiveness of interferon-alpha (IFN-alpha) in MM, which has also recently been shown to function as a survival factor for MM cells. The effects of different doses of native human leukocyte interferon-alpha (nhIFN-alpha), recombinant human interferon-alpha2a (rhIFN-alpha2a) and recombinant human interferon-alpha2b (rhIFN-alpha2b) on in vitro P3-X63-Ag8.653 mouse myeloma cell growth were compared. A statistically significant dose-dependent reduction in cell viability following cell culture with nhIFN-alpha was observed. On the other hand, a statistically significant increase in cell viability was observed following cell culture with rhIFN-alpha2a and rhIFN-alpha2b, but only in relation to the control group and seemingly without dose dependency. These results highlight the importance of the type of human IFN-alpha used in the treatment and study of MM, and suggest that nhIFN-alpha may have a role in future personalized therapy approaches.

A role for IFN-lambda1 in multiple myeloma B cell growth

Multiple myeloma (MM) is a progressive disease that results from dysregulated proliferation of plasma cells. Although, causative factors such as genetic events and altered expression of anti-apoptotic factors have been described in a number of patients, the mechanistic details that drive myeloma development and continued growth of malignant cells remain largely undefined. Numerous growth factors, including interleukin (IL)-6, Insulin-like growth factor-1 and IL-10 have been shown to promote growth of MM cells suggesting a significant role for cytokines in this disease. Interferon (IFN)-lambda1 is a new member of the Class II cytokine family that, similar to IFN-alpha, has been shown to mediate viral immunity. In light of data supporting a role for cytokines in myeloma, we investigated the significance of IFN-lambda1 on myeloma cell biology. Our studies show for the first time that myeloma cells bind to soluble IFN-lambda1, and that IFN-lambda1 induces myeloma cell growth and protects against dexamethasone-induced cell death. Our data also show that IFN-lambda1 induces phosphorylation of STAT1, STAT3 and Erk. Taken together, our results suggest that IFN-lambda1 may regulate myeloma cell biology and could prove to be therapeutically important.

PET Positive Generalized Lymphadenopathy and Splenomegaly Following Interferon-alfa-2b Adjuvant Therapy for Melanoma

Interferon-alfa (IFN-alpha) is used in patients with various inflammatory and neoplastic disorders. We recently encountered fluorodeoxyglucose (FDG) uptake in generalized lymphadenopathy, splenomegaly, and the marrow in a patient receiving high dose interferon-alpha-2b (IFN-alpha) as adjuvant therapy for the treatment of malignant melanoma. Biopsy of an enlarged hypermetabolic axillary lymph node revealed only a reactive node. Discontinuation of IFN-alpha caused regression of splenomegaly and lymphadenopathy within 3 months.A marrow "hyperstimulation" pattern that can include the spleen is a well-recognized phenomenon on (fluorodeoxyglucose) FDG positron emission tomography/computed tomography (PET/CT) scans in patients receiving chemotherapeutic agents like interferon, though classically due to colony stimulating factors, but does not generally include lymphadenopathy. This case, which likely reflects an interferon-induced pseudolymphoma, highlights the importance of a drug history and clinical correlation for the proper interpretation of FDG PET/CT scans.

Ectopic and IFN-induced expression of Fas overcomes resistance to Fas-mediated apoptosis in multiple myeloma cells

Multiple myeloma (MM) is an as-yet incurable B-cell malignancy. Increased survival in vitro is a hallmark of MM cells, implying that a therapeutic potential may lie in circumventing antiapoptotic signals. We have previously reported that interferons (IFNs) sensitize MM cells to Fas/CD95-mediated apoptosis. In the present study, we explore the mechanism underlying this effect. In a wide screening of apoptosis-related genes, Apo2L/TRAIL (tumor necrosis factor [TNF]-related apoptosis inducing ligand) and Fas were identified as IFN targets. Sensitization to Fas-mediated apoptosis by IFNs was not affected by blocking Apo2L/TRAIL, suggesting that Apo2L/TRAIL is not a key mediator in this process. In contrast, we found that an elevated Fas expression was functionally linked to increased susceptibility to Fas-mediated apoptosis. This was further supported by the finding that IFN treatment enhanced Fas-mediated caspase-8 activation, one of the earliest signaling events downstream receptor activation. In addition, IFN treatment attenuated the interleukin 6 (IL-6)-dependent activation of signal transducer and activator of transcription 3 (Stat3), interfering with a known survival pathway in MM that has previously been linked with resistance to Fas-mediated apoptosis. Taken together, our results show that IFN-induced up-regulation of Fas sensitizes MM cells to Fas-mediated apoptosis and suggest that attenuation of Stat3 activation may be a potentially important event in this process.

A role for Janus kinases in crosstalk between ErbB3 and the interferon-alpha signaling complex in myeloma cells

Receptor crosstalk is an emerging and recurrent theme in cytokine and growth factor signaling; however, insight into the mechanism(s) underlying these interactions remains limited. Recently, we reported that crosstalk occurs between ErbB3 and the interferon alpha (IFN-alpha) signaling complex in the myeloma cell line KAS-6/1 and that this crosstalk contributes to the regulation of cell proliferation. In this study, we examined the mechanism underlying the transactivation of ErbB3 in the IFN-alpha growth-responsive KAS-6/1 cells. The examination of IFN-alpha receptor 1 and 2 (IFNAR1 and IFNAR2) levels revealed that the KAS-6/1 cell line overexpresses IFNAR1 relative to other myeloma cell lines that are growth arrested by IFN-alpha. Subsequent investigation of Tyk2, which is constitutively associated with IFNAR1, demonstrated that Tyk2 activation is uniquely sustained in the KAS-6/1 cell line following IFN-alpha stimulation. Interestingly, silencing of Tyk2 expression via siRNA resulted in attenuation of ErbB3 transactivation. However, inhibition of Jak1 expression also decreased IFN-alpha-induced tyrosine phosphorylation of ErbB3. Finally, siRNA downregulation of Tyk2 and Jak1 was found to decrease IFN-alpha-stimulated proliferation. These findings validate our previous report of ErbB3 involvement in IFN-alpha-induced proliferation and further suggest that both Janus kinase members, Tyk2 and Jak1, play a role in the transactivation of ErbB3 in this model system.

Atypical expression of ErbB3 in myeloma cells: cross-talk between ErbB3 and the interferon-alpha signaling complex

We have previously demonstrated that the responsiveness of multiple myeloma (MM) cells to interferon-alpha (IFN-alpha) stimulation is variable, with an atypical growth response displayed by some cells. Here we report the ability of IFN-alpha to induce tyrosine phosphorylation of a 180 kDa band in the KAS-6/1 MM cell line, which is growth responsive to IFN-alpha. Further characterization demonstrated that this band corresponds to ErbB3. To our knowledge, this is the first report of ErbB3 expression in a cell type of the hematopoietic lineage. Although ErbB receptors have been shown to crosscommunicate with various other receptors, our results show for the first time that the IFN-alpha receptor can crosscommunicate with ErbB3. To address the significance of these observations, we transfected ErbB3-negative DP-6 MM cells with ErbB3 and used siRNA to silence ErbB3 in the KAS-6/1 cell line. Although IFN-alpha transactivated ErbB3 in the DP-6 transfectants, it did not confer growth responsiveness to IFN-alpha. Interestingly, silencing ErbB3 expression in the KAS-6/1 cells decreased the overall growth response to IFN-alpha and to interleukin-6. These results suggest that ErbB3 expression alone does not uniquely confer IFN-alpha growth responsiveness, but instead may amplify proliferation rates in MM cells that have acquired atypical expression of this receptor.

Interferon alpha extends the survival of human myeloma cells through an upregulation of the Mcl-1 anti-apoptotic molecule

We have recently reported that Mcl-1, an anti-apoptotic member of the Bcl-2 family, is upregulated by interleukin (IL)-6 in human myeloma cells through the janus kinase/signal transducers and activators of transduction (JAK/STAT) pathway. In the current study, we have explored the effects of interferon (IFN)-alpha, a cytokine which has been shown to increase myeloma cell survival. Our results demonstrate that IFN-alpha potently upregulates Mcl-1 on both myeloma cell lines and purified native myeloma cells. Of note, this upregulation is not due to an induction of an IL-6 autocrine loop. Furthermore, we showed that IL-6 and IFN-alpha had no additive effect on Mcl-1 upregulation, suggesting that both cytokines act through a common mechanism. Finally, the analysis of signalling transduction pathways strongly suggests that Mcl-1 upregulation induced by IFN-alpha depends on STAT3 activation. Altogether, our data show that IFN-alpha has an IL-6-like effect on human myeloma cells and suggest that it could be deleterious in some patients.

Viewpoint on the impact of interferon in the treatment of multiple myeloma: benefit for a small proportion of patients?

Interferon-alpha (IFN-alpha) generally inhibits myeloma cell growth. However, a growth stimulatory effect for myeloma cells has also been reported. In patients with untreated multiple myeloma (MM) IFN-alpha, used as a single agent, produced an objective response rate ranging from 10 to 25%. In previously untreated patients: (1) the time to response is short, (2) the median duration of response is similar to the duration of response observed in patients given chemotherapy, and (3) the patients who are more likely to benefit are those with IgA myeloma type. Concerning the results of IFN-alpha given as a single agent in relapsing and resistant MM, they are poor, with a response rate ranging between 10-20%. The combination of high-dose glucocorticoids and IFN-alpha for relapsing/resistant patients produced controversial results. Some studies showed an increased response rate and/or longer survival with chemotherapy plus IFN-alpha versus chemotherapy alone in previously untreated patients. In contrast, most reports did not show a significant increase in response rate or survival benefit by adding IFN-alpha to the initial chemotherapy. Perhaps the most encouraging role for IFN in MM is as maintenance therapy in patients responding to first line treatment (ie conventional chemotherapy followed or not by high-dose intensification/autotransplantation). In spite of that, several reports failed to show longer response duration. The majority of studies have shown a modest but significant prolongation in response duration in favour of the IFN arm. However, most of these studies have failed to show a significant survival advantage with IFN maintenance. A meta-analysis, by the Myeloma Trialists' Collaborative Group in Oxford, based on the individual data from 4012 patients included in 24 randomized trials (induction and/or maintenance) has shown that IFN produced a moderate improvement in relapse-free survival and a minor improvement in overall survival. In summary, the only role of IFN in MM is as maintenance treatment after a response is achieved. However, looking at the published data, it seems that the vast majority of patients do not benefit from IFN maintenance, while a small proportion of them, in the range of 5-10%, obtain a significant prolongation in event-free survival and overall survival. Unfortunately, there are no predictive factors that can identify the patients who are likely to benefit from IFN maintenance.

Nonsecretory myeloma, immunoglobulin D myeloma, and plasma cell leukemia

Nonsecretory myeloma, which accounts for 1% to 5% of all myelomas, is characterized by the absence of detectable M-protein in serum and urine. The presenting features of nonsecretory myeloma are similar to those in patients with a detectable M-protein, except for the absence of renal function impairment. The response to therapy and survival of patients with nonsecretory myeloma are similar to those of patients with measurable M-protein. Immunoglobulin D myeloma represents 2% of all myelomas. Patients with IgD myeloma usually present with a small band or no evident M-spike on serum electrophoresis and heavy light-chain proteinuria. Thus, IgD myeloma can be considered a variant of Bence Jones myeloma; the presence of the IgD M-protein and the predominance of the lambda light chain are the only distinctive features. The median survival of patients with IgD myeloma is almost 2 years, with one fifth of them surviving for more than 5 years. Plasma cell leukemia is also a rare form of plasma cell dyscrasia (2% to 4% of all myelomas). The primary form accounts for 60% of the cases. In primary PCL, the constellation of adverse biologic prognostic factors in patients with advanced aggressive myeloma is already present at diagnosis. In fact, primary PCL has a more aggressive clinical presentation than MM, with a higher frequency of extramedullary involvement, anemia, thrombocytopenia, hypercalcemia, and renal failure. Treatment with a single alkylating agent plus prednisone is not appropriate. Combination chemotherapy with VAD, cyclophosphamide and etoposide, or VCMP/VBAP is a better initial option. Given the poor prognosis of primary PCL, intensification with high-dose therapy followed by stem cell rescue should be offered to affected patients.

IFN-α Is a Survival Factor for Human Myeloma Cells and Reduces Dexamethasone-Induced Apoptosis

IFN-α is used as a maintenance therapy in patients with multiple myeloma, but its benefit is a matter of controversy. In vitro studies show that IFN-α can both stimulate and inhibit myeloma cell proliferation. We have tested the effect of IFN-α on the survival of myeloma cell lines and primary plasma cells. IFN-α significantly reduced the apoptosis induced by removal of IL-6 in four IL-6-dependent myeloma cell lines. It also reduced the level of apoptosis induced by dexamethasone in these cell lines as well as in purified primary myeloma cells from seven patients. IFN-α promoted the survival of myeloma cells, which, following removal of IL-6, were blocked in G1 and died. However, unlike IL-6, IFN-α-treated cells remained mainly blocked in the G1 phase of the cycle. While the effects of IL-6 are mediated through stimulation of its gp130 receptor subunit, the IFN-α-induced survival of myeloma cells was independent of gp130 transducer activation (as demonstrated using a neutralizing anti-gp130 Ab). However, the signal transduction cascades activated by these two cytokines share at least some common elements, since stimulation with either IFN-α or IL-6 resulted in STAT3 phosphorylation. These results indicate that IFN-α promotes the survival, but not the proliferation, of myeloma cells, preventing the apoptosis induced by removal of IL-6 or addition of dexamethasone. This survival factor activity may explain the conflicting reports on the effects of IFN-α on myeloma cell proliferation.

Differential myeloma cell responsiveness to interferon-alpha correlates with differential induction of p19(INK4d) and cyclin D2 expression

Interferon-alpha (IFN-alpha) has been used as therapy for the treatment of a variety of viral diseases and malignancies including multiple myeloma. The effectiveness of interferon-alpha in treating multiple myeloma, however, has been somewhat variable, and the mechanism(s) accounting for this is not well understood. As a means to examine the basis for the differential effectiveness of this cytokine, we have analyzed IFN-alpha-mediated modulation of the cell cycle in two human myeloma cell lines. These two cell lines, ANBL-6 and KAS-6/1, display dramatically different outcomes in response to this cytokine. Although IFN-alpha inhibited the growth of ANBL-6 cells by blocking cell cycle progression from G0/G1 to S phase, IFN-alpha stimulated cell cycle progression in KAS-6/1 cells. Moreover, the effects of IFN-alpha on cell cycle progression correlated with the phosphorylation status of the retinoblastoma protein. Of interest, IFN-alpha increased cyclin D2 expression and cyclin-dependent kinase activity in the KAS-6/1 cells but not in the ANBL-6 cells. To determine whether the differential effects of IFN-alpha on myeloma cell cycle progression could also result from differences in the expression of cyclin-dependent kinase inhibitors, we examined the effects of IFN-alpha on the induction of cyclin-dependent kinase inhibitors with broad regulatory function (p21 and p27) and those with specificity for G1-associated cyclin-cyclin-dependent kinase complexes (p15, p16, p18, and p19). Although we failed to detect an effect of IFN-alpha on expression levels of p21, p15, p16, or p18, IFN-alpha treatment of the ANBL-6 cell line resulted in induction of p19 expression, whereas it was without effect on the KAS-6/1 cell line. These results suggest that heterogeneity in IFN-alpha-mediated growth effects in myeloma cells correlates with differential induction of cyclin D2 and p19(INK4d) expression.

Interferon in the Treatment of Multiple Myeloma

BACKGROUND: The role of interferon (IFN) in the treatment of multiple myeloma has been investigated for nearly two decades. The mechanisms underlying antitumor activity of IFN may be mediated by antiproliferative and immunomodulatory effects. The benefits of treatment remain controversial, and guidelines for the use of IFN in myeloma are needed. This review evaluates available data on the impact of IFN therapy on multiple myeloma. METHODS: A MEDLINE search of published prospective, randomized trials of IFN in multiple myeloma provided the data included in this review, as well as selected abstracts presented at international meetings. RESULTS: IFN has complex and pleiotropic effects on human myeloma lines and ex vivo myeloma cells. An antiproliferative effect with disruption of the IL-6-mediated growth loop may be crucial, but biologic heterogeneity in myeloma may have important clinical implications for response to IFN. IFN has demonstrable antitumor activity in multiple myeloma but appears to have a modest effect on overall survival when combined with chemotherapy during induction or when used as maintenance therapy. Most studies have shown a prolongation of the plateau phase of disease with IFN of variable duration of between four and 12 months. CONCLUSIONS: A reliable estimate of the benefit of IFN in the overall population of patients with myeloma is difficult to determine with discordant results from different trials. Possible sources of heterogeneity in randomized trials need to be identified, and recognition of subsets of patients who may benefit is important. Cost-benefit analyses with integration of quality-of-life data are essential for developing guidelines for the use of IFN in myeloma.

Differential human multiple myeloma cell line responsiveness to interferon-alpha. Analysis of transcription factor activation and interleukin 6 receptor expression

Although IFN-alpha is commonly used as maintenance treatment for multiple myeloma patients, its effectiveness is varied. In this study, we have used a panel of IL-6 responsive myeloma cell lines that vary remarkably in responsiveness to IFN-alpha. Three cell lines were growth arrested by IFN-alpha; however, IFN-alpha significantly stimulated growth of the fourth cell line, KAS-6/1. Our studies have focused on elucidating the mechanism of differential IFN-alpha responsiveness. First, we have shown that IFN-alpha-stimulated growth of the KAS-6/1 cells did not result from induction of autocrine IL-6 expression. Second, analysis of Stats 1, 2, and 3 and IFN regulatory factor-1 (IRF-1) and IRF-2 activation failed to reveal differences between the IFN-alpha growth-arrested or growth-stimulated cells. Third, although IFN-alpha treatment of the IFN-alpha growth-inhibited cell lines reduced IL-6 receptor (IL-6R) expression, IFN-alpha also reduced KAS-6/1 IL-6R expression. Finally, although IFN-alpha treatment reduced IL-6R numbers on each cell line, analysis of Stat protein activation revealed that the receptors were still functional. We conclude that myeloma cell responsiveness to IFN-alpha is heterogeneous and that mechanisms of IFN-alpha-mediated growth inhibition other than IL-6R downregulation must exist in myeloma. Identification of these mechanisms may allow development of agents that are more universally effective than IFN-alpha.

Myeloma biology and therapy. Present status and future developments

Recent progress in cytokine studies has made it possible to understand the pathophysiological roles of cytokines in multiple myeloma. Specifically, interleukin (IL)-6 is a potent growth factor for myeloma cells and is also responsible for the progressive bone resorption characteristic of this disease. On the basis of this evidence, clinical trials to interfere with IL-6 signals have been initiated for the treatment of patients with advanced myeloma. Such a new therapeutic approach as well as myeloblative therapy should be able to provide us with the breakthrough needed to prevail over this so far incurable disease.

[Use of interferon alpha in multiple myeloma]

Alpha Interferon has been used for fifteen years in the management of patients with multiple myeloma. However this indication remains controversial. Seven multicenter randomized trials have compared alpha Interferon with observation in patients responding to conventional chemotherapy. Three of these studies have given negative results. In the other four, alpha Interferon therapy has prolonged remission duration but in none of them has the overall survival been significantly prolonged. After intensive treatments the results of only one study are available and are in favour of alpha Interferon. Seven randomized studies have tested the impact of a combination chemotherapy plus alpha Interferon as compared to chemotherapy alone. Only one has shown a significant benefit for patients receiving chemotherapy plus natural alpha Interferon. This benefit has been limited of IgA and BJ myelomas and to stage II myelomas. Finally, the combination high dose dexamethasone-alpha Interferon has given promising preliminary results which justify prospective ongoing studies. These clinical results are analyzed in relation to the in vitro data.

Clinical toxicity of the interferons

Since their initial description in 1957, the interferons (IFNs) have been increasingly used to treat a wide array of diseases. Acute adverse effects, i.e. 'flu-like' syndromes, hypo- or hypertension, tachycardia, headache, myalgias and gastrointestinal disorders, occur within the first hour or day after starting treatment. They are seldom treatment-limiting and are easily manageable. Sub-acute and chronic effects develop after several days, usually within 2 and 4 weeks of therapy. The most typical is neurological toxicity, including fatigue/asthenia, and behavioural and cognitive changes. Such symptoms may seriously impair quality of life and result in treatment discontinuation. Seizures have seldom been described. Other infrequent central nervous system adverse effects include vertigo, cramp and oculomotor nerve paralysis. Distal paraesthesias and peripheral neuropathy have been reported. IFN-associated autoimmunity is quite rare but a matter of concern. Biological or clinical manifestations usually require several months to become apparent. Autoantibodies have been shown to develop in most patients but have been inconsistently associated with clinical symptoms of systemic lupus erythematosus, rheumatoid-like arthritis and thyroiditis. Both hypo- and hyperthyroidism have been described but are usually reversible. Other infrequent autoimmune reactions include diabetes, pemphigus and worsening of multiple sclerosis. Although several patients present with a pre-existing autoimmune disorder, no predisposing factor has been clearly established. While hypotension and tachycardia are the most frequent acute cardiovascular complications, a few additional cases of cardiac arrhythmias and myocardial ischaemia have been reported after a short course or several weeks of treatment. These latter complications do not appear to be dose-dependent or age-related. Isolated cases of congestive heart failure have also been described. Mild proteinuria has been observed in 15 to 25% of patients, but acute renal toxicity is uncommon. A transient rise in serum aminotransferase levels is frequently noted during the first stage of therapy, especially in patients receiving the highest dosages. Direct hepatotoxicity is extremely rare. Autoimmune hepatitis, which is ill-diagnosed as chronic viral hepatitis, and de novo induction of autoimmune hepatitis, account for the majority of liver diseases. Haematotoxicity is relatively common but mild to moderate, and develops gradually during the first weeks of treatment. Neutropenia is the most common haematological toxicity, but is usually not dose-limiting and resolves rapidly upon drug discontinuation. Myelosuppression, autoimmune and immune allergic haemolytic anaemias and thrombocytopenias have seldom been described. Cutaneous adverse effects comprised nonspecific erythema and hair loss and, less frequently, vasculitis, local ulcerations at the site of injection and exacerbation of psoriasis.(ABSTRACT TRUNCATED AT 250 WORDS)