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Multiple Myeloma

(Myelomatosis; Plasma Cell Myeloma)

By

James R. Berenson

, MD, Institute for Myeloma and Bone Cancer Research

Last full review/revision Sep 2019| Content last modified Sep 2019
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Topic Resources

Multiple myeloma is a cancer of plasma cells that produce monoclonal immunoglobulin and invade and destroy adjacent bone tissue. Common manifestations include lytic lesions in bones causing pain, and/or fractures, renal insufficiency, hypercalcemia, anemia, and recurrent infections. Diagnosis typically requires demonstration of M-protein (sometimes present in urine and not serum but rarely absent entirely) and/or light-chain proteinuria, and excessive plasma cells in the bone marrow. Specific treatment most often includes some combination of conventional chemotherapy, corticosteroids, and one or more of the newer agents such as proteasome inhibitors (eg, bortezomib, carfilzomib, ixazomib), immunomodulating agents (eg, lenalidomide, thalidomide, pomalidomide), or monoclonal antibodies (eg, daratumumab, elotuzumab). High-dose melphalan followed by autologous peripheral blood stem cell transplantation may also be used.

The incidence of multiple myeloma is 2 to 4/100,000. Male:female ratio is 1.6:1, and the median age is about 65 years. Prevalence in blacks is twice that in whites. Etiology is unknown, although chromosomal and genetic factors, radiation, and chemicals have been suggested.

Pathophysiology

The M-protein (monoclonal immunoglobulin protein) produced by the malignant plasma cells is IgG in about 55% of myeloma patients and IgA in about 20%; of patients producing either IgG or IgA, 40% also have Bence Jones proteinuria, which is free monoclonal kappa (κ) or lambda (λ) light chains in the urine. In 15 to 20% of patients, plasma cells secrete only Bence Jones protein. IgD myeloma accounts for about 1% of cases. Rarely, patients have no M-protein in blood and urine, although the currently used serum free light chain assay now demonstrates monoclonal light chains in many of these formerly so-called nonsecretory patients.

Diffuse osteoporosis or discrete osteolytic lesions develop, usually in the pelvis, spine, ribs, femur, humerus, and skull. Lesions are caused by bone replacement by expanding plasmacytomas or by cytokines that are secreted by malignant plasma cells that activate osteoclasts and suppress osteoblasts. The osteolytic lesions are usually multiple; occasionally, they are solitary intramedullary masses. Increased bone loss may also lead to hypercalcemia. Extraosseous solitary plasmacytomas are unusual but may occur in any tissue, especially in the upper respiratory tract.

In many patients, renal failure is present at diagnosis or develops during the course of the disorder. Renal failure has many causes, and most commonly, it results from deposition of light chains in the distal tubules (myeloma-related kidney disease) or hypercalcemia. Patients also often develop anemia usually due to kidney disease or suppression of erythropoiesis by cancer cells but sometimes also due to other unrelated causes, including iron deficiency or vitamin B12 deficiency.

Because of lack of normal antibodies and other immune dysfunction, some patients have increased susceptibility to bacterial infection. Viral infections, especially herpes zoster infections, are increasingly occurring as a result of newer treatment modalities, especially use of the proteasome inhibitors bortezomib, ixazomib, and carfilzomib and monoclonal antibodies such as daratumumab and elotuzumab. Amyloidosis occurs in 10% of myeloma patients, most often in patients with lambda-type M-proteins.

Table
icon

Variant Expressions of Multiple Myeloma

Form

Characteristics

Extramedullary plasmacytoma

Plasmacytomas that occur outside of the bone marrow

Solitary plasmacytoma of bone

Single bone plasmacytomas, which usually produce no M-protein

Osteosclerotic myeloma (POEMS syndrome)

Polyneuropathy (chronic inflammatory polyneuropathy)

Organomegaly (hepatomegaly, splenomegaly, or lymphadenopathy)

Endocrinopathy (eg, gynecomastia, testicular atrophy)

M-protein

Skin changes (eg, hyperpigmentation, excess hair)

Nonsecretory myeloma

Absence of M-protein in serum and urine

Presence of M-protein in plasma cells

Symptoms and Signs

Persistent bone pain (especially in the back or thorax), renal failure, and recurring bacterial infections are the most common problems on presentation, but many patients are identified when routine laboratory tests show an elevated total protein level in the blood, proteinuria, or unexplained anemia or renal failure. Pathologic fractures (ie, fractures that occur with minimal or no trauma) are common, and vertebral collapse may lead to spinal cord compression and paraplegia. Symptoms of anemia predominate or may be the sole reason for evaluation in some patients, and a few patients have manifestations of hyperviscosity syndrome. Peripheral neuropathy, carpal tunnel syndrome (especially with associated amyloid disease), abnormal bleeding, and symptoms of hypercalcemia (eg, polydipsia, dehydration) are common. Patients may also present with renal failure. Lymphadenopathy and hepatosplenomegaly are unusual.

Diagnosis

  • Complete blood count (CBC) with platelets, peripheral blood smear, erythrocyte sedimentation rate (ESR), and chemistry panel (blood urea nitrogen [BUN], creatinine, calcium, uric acid, lactate dehydrogenase [LDH])

  • Serum and urine protein (on a 24-hour urine collection) electrophoresis followed by immunofixation; quantitative immunoglobulins; serum free light chains

  • X-rays (skeletal survey)

  • Bone marrow examination, including conventional cytogenetics and fluorescent in situ hybridization studies (FISH)

Multiple myeloma is suspected in patients > 40 years with persistent unexplained bone pain, particularly at night or at rest, other typical symptoms, or unexplained laboratory abnormalities, such as elevated blood protein or urinary protein, hypercalcemia, renal insufficiency, or anemia. Laboratory evaluation includes routine blood tests, LDH, serum beta-2 microglobulin, urine and serum immune and protein electrophoresis, serum free light chains, x-rays, and bone marrow examination (for review, see [1, 2]).

Routine blood tests include CBC, ESR, and chemistry panel. Anemia is present in 80% of patients, usually normocytic-normochromic anemia with formation of rouleaux, which are clusters of 3 to 12 red blood cells that occur in stacks. White blood cell and platelet counts are usually normal. ESR usually is > 100 mm/hour; BUN, serum creatinine, LDH, beta-2 microglobulin, and serum uric acid may be elevated. Anion gap is sometimes low. Hypercalcemia is present at diagnosis in about 10% of patients.

Immune and protein electrophoresis is done on a serum sample and on a urine sample concentrated from a 24-hour collection to quantify the amount of urinary M-protein. Serum electrophoresis identifies M-protein in about 80 to 90% of patients. The remaining 10 to 20% are usually patients with only free monoclonal light chains (Bence Jones protein) or IgD. They almost always have M-protein detected by urine protein electrophoresis.

Immunofixation electrophoresis can identify the immunoglobulin class of the M-protein (IgG, IgA, or uncommonly IgD, IgM, or IgE) and can often detect light-chain protein if serum immunoelectrophoresis is falsely negative; immunofixation electrophoresis is done even when the serum test is negative if multiple myeloma is strongly suspected.

Serum free light-chain analysis with delineation of kappa and lambda ratios helps confirm the diagnosis and can also be used to monitor efficacy of therapy and provide prognostic data.

Serum level of beta-2 microglobulin is measured if diagnosis is confirmed or very likely and along with serum albumin is used to stage patients as part of the international staging system (see table Revised International Staging System for Multiple Myeloma). Beta-2 microglobulin is a small protein on the membrane of all cells. Its concentration varies directly with tumor mass and severity of renal dysfunction.

Table
icon

Revised International Staging System for Multiple Myeloma

Stage

Criteria

5-year Survival (%)

I

Beta-2 microglobulin < 3.5 mcg/mL (< 297 nmol/L)

and

Serum albumin ≥ 3.5 g/dL (≥ 35 g/L)

Normal LDH

Standard-risk cytogenetic abnormalities by FISH

82

II

Not stage I or III

62

III

Beta-2 microglobulin ≥ 5.5 mcg/mL (466 nmol/L)

High-risk cytogenetic abnormalities by FISH

High LDH

40

FISH = fluorescent in situ hybridization; LDH = lactate dehydrogenase.

X-rays include a skeletal survey (ie, plain x-rays of skull, long bones, spine, pelvis, and ribs). Punched-out lytic lesions or diffuse osteoporosis is present in 80% of cases. Radionuclide bone scans usually are not helpful. MRI can provide more detail and is obtained if specific sites of pain or neurologic symptoms are present. PET-CT may provide prognostic information and can help determine whether patients have solitary plasmacytoma or multiple myeloma.

Bone marrow aspiration and biopsy are done and reveal sheets or clusters of plasma cells; myeloma is diagnosed when >10% of the cells are of this type. However, bone marrow involvement is patchy; therefore, some samples from patients with myeloma may show <10% plasma cells. Still, the number of plasma cells in bone marrow is rarely normal. Plasma cell morphology does not correlate with the class of immunoglobulin synthesized. Chromosomal studies on bone marrow (eg, using cytogenetic testing methods such as fluorescent in situ hybridization [FISH] and immunohistochemistry) may reveal specific karyotypic abnormalities in plasma cells associated with differences in survival.

Diagnosis and differentiation from other malignancies (eg, metastatic carcinoma, lymphoma, leukemia) and monoclonal gammopathy of undetermined significance typically require multiple criteria:

  • Clonal bone marrow plasma cells or plasmacytoma

  • M-protein in plasma and/or urine

  • Organ impairment (hypercalcemia, renal insufficiency, anemia, or bony lesions)

In patients without serum M protein, myeloma is indicated by Bence Jones proteinuria > 200 mg/24 hour or abnormal serum free light chain levels, osteolytic lesions (without evidence of metastatic cancer or granulomatous disease), and sheets or clusters of plasma cells in the bone marrow.

Diagnosis references

  • 1. Rajkumar SV, Kumar S: Multiple myeloma: Diagnosis and treatment. Mayo Clinic Proc 91(1):101-119, 2016. doi: 10.1016/j.mayocp.2015.11.007

  • 2. Rajkumar SV: Myeloma today: Disease definitions and treatment advances. Am J Hematol 91(1):90-100, 2016. doi: 10.1002/ajh.24392

Prognosis

The disease is progressive and incurable, but median survival has recently improved to > 5 years as a result of advances in treatment. Unfavorable prognostic signs at diagnosis are lower serum albumin, higher beta-2 microglobulin levels, elevated LDH levels, and specific cytogenetic abnormalities in the tumor cells. Patients initially presenting with renal failure also do poorly unless kidney function improves with therapy (which typically happens with current treatment options).

Because multiple myeloma is ultimately fatal, patients are likely to benefit from discussions of end-of-life care that involve their doctors and appropriate family and friends. Points for discussion may include advance directives, the use of feeding tubes, and pain relief.

Treatment

  • Chemotherapy for symptomatic patients

  • Thalidomide, lenalidomide, or pomalidomide, and/or bortezomib, carfilzomib, or ixazomib, plus corticosteroids and/or conventional chemotherapy

  • Monoclonal antibodies, including elotuzumab and daratumumab

  • Maintenance therapy with corticosteroids, thalidomide, and/or lenalidomide, and proteasome inhibitors, especially oral ixazomib

  • Possibly autologous stem cell transplantation

  • Possibly radiation therapy to specific symptomatic areas that do not respond to systemic therapy

  • Treatment of complications (anemia, hypercalcemia, renal insufficiency, infections, and skeletal lesions (especially those associated with high risk of fracture)

Treatment of myeloma has improved in the past 2 decades, and long-term survival is a reasonable therapeutic target (1–4). Therapy involves direct treatment of malignant cells in symptomatic patients or those with myeloma-related organ dysfunction (anemia, renal dysfunction, hypercalcemia, or bone disease).

Risk factors for requiring rapid treatment of myeloma among patients initially presenting with organ dysfunction include > 60% plasma cells in bone marrow, > 1 lesion on MRI, and serum free light chain levels > 100 mg/L. Thus, these patients are now considered to have active myeloma and require immediate treatment even though nearly all randomized clinical trials of early treatment of these patients have not yet shown an improvement in overall survival. Patients without these risk factors or end-organ dysfunction probably do not benefit from immediate treatment, which is usually withheld until symptoms or complications develop. .

Treatment of malignant cells

In the past, initial treatment of multiple myeloma consisted of conventional chemotherapy with oral melphalan and prednisone given in cycles of 4 to 6 weeks for 8 to 12 cycles with monthly evaluation of response. However, superior outcomes have been achieved with the addition of either the proteasome inhibitor bortezomib (or carfilzomib) or the immunomodulatory agents lenalidomide or thalidomide. Other chemotherapeutic drugs, including cyclophosphamide, bendamustine, doxorubicin, and its analog, liposomal pegylated doxorubicin, also are more effective when combined with an immunomodulatory drug (thalidomide, lenalidomide, or bortezomib). Studies suggest better survival when initial treatment includes both bortezomib and lenalidomide with corticosteroids. In addition, the addition of the monoclonal antibody daratumumab to bortezomib and dexamethasone as part of initial treatment appears to improve outcomes.

Response to treatment (see table Defining Response to Cancer Treatment) is indicated by decreases in serum and urine M-protein, decreases in levels of the involved serum free light chain, increases in numbers of red blood cells, improvement in renal function among patients presenting with renal failure, and normalization of calcium levels among those presenting with elevated levels. Bone pain and fatigue should also decrease.

Autologous peripheral blood stem cell transplantation may be considered for patients who have adequate cardiac, hepatic, pulmonary, and renal function, particularly those whose disease is stable or responsive after several cycles of initial therapy. However, studies suggest that the newer treatment options are highly effective and may make transplantation less often necessary or unnecessary altogether.

Allogeneic stem cell transplantation after nonmyeloablative chemotherapy (eg, low-dose cyclophosphamide and fludarabine) or low-dose radiation therapy can produce myeloma-free survival of 5 to 10 years in some patients. However, allogeneic stem cell transplantation with myeloablative or nonmyeloablative chemotherapy remains experimental because of the high morbidity and mortality resulting from graft vs host disease.

Treatment of relapsed or refractory myeloma

In relapsed or refractory myeloma, combinations of a proteasome inhibitor (bortezomib, ixazomib, or carfilzomib) with an immunomodulatory agent (thalidomide, lenalidomide, or pomalidomide) and chemotherapy or corticosteroids may be used. These drugs are usually combined with other effective drugs that the patient has not yet been treated with, although patients with prolonged remissions may respond to retreatment with the same regimen that led to the initial remission. Patients who fail to respond to a given combination of drugs may respond when another drug in the same class (eg, proteasome inhibitors, immunomodulatory agents, chemotherapeutic drugs) is substituted.

Newer monoclonal antibodies may also be highly effective in relapsed or refractory myeloma and include daratumumab and elotuzumab. Both antibodies are more effective when combined with lenalidomide or pomalidomide and dexamethasone. Daratumumab also shows better results when combined with bortezomib and dexamethasone.

Maintenance therapy

Maintenance therapy has been tried with nonchemotherapeutic drugs, including interferon alfa, which prolongs remission but does not improve survival and is associated with significant adverse effects. Following a response to corticosteroid-based regimens, corticosteroids alone are effective as a maintenance treatment. Thalidomide may also be effective as a maintenance treatment, and studies show that lenalidomide alone or with corticosteroids is also effective maintenance treatment. However, there is some concern about secondary malignancy among patients receiving long-term lenalidomide therapy, especially after autologous stem cell transplantation, and the risk of developing secondary cancers must be weighed against improved survival. In addition, the oral proteasome inhibitor ixazomib is effective as a single agent in the maintenance setting. Whether the combination of ixazomib with lenalidomide is more effective in this setting is yet unknown.

Treatment of complications

In addition to direct treatment of malignant cells, therapy must also be directed at complications, which include

  • Anemia

  • Hypercalcemia

  • Hyperuricemia

  • Infections

  • Renal insufficiency

  • Skeletal lesions

Anemia can be treated with recombinant erythropoietin (40,000 units subcutaneously once a week) in patients whose anemia is inadequately relieved by chemotherapy. If anemia causes cardiovascular or significant systemic symptoms, packed red blood cells are transfused. Plasma exchange is indicated if hyperviscosity develops. Often patients are iron deficient and require intravenous iron. Patients with anemia should have periodic measurement of serum iron, transferrin, and ferritin levels to monitor iron stores as well as vitamin B12. levels

Hypercalcemia is treated with vigorous saluresis, IV bisphosphonates (preferably zoledronic acid) after rehydration, and sometimes with calcitonin or prednisone. Patients should avoid calcium-containing foods, calcium supplements, and vitamin D.

Hyperuricemia may occur in some patients with high tumor burden and underlying metabolic problems. However, most patients do not require allopurinol. Allopurinol or rasburicase is indicated for patients with high levels of serum uric acid or high tumor burden and a high risk of tumor lysis syndrome with treatment.

Infection is more likely during chemotherapy-induced neutropenia. In addition, infections with the herpes zoster virus are occurring more frequently in patients treated with newer antimyeloma drugs, especially the proteasome inhibitors bortezomib, carfilzomib, or ixazomib and the monoclonal antibodies daratumumab or elotuzumab. Documented bacterial infections should be treated with antibiotics; however, prophylactic use of antibiotics is not routinely recommended.

Prophylactic use of antiviral drugs (eg, acyclovir, valganciclovir, famciclovir) is indicated for patients receiving a proteasome inhibitor (bortezomib, carfilzomib, ixazomib) or a monoclonal antibody (daratumumab, elotuzumab).

Prophylactic IV immune globulin may reduce the risk of infection but is generally reserved for patients with frequent recurrent infections. Pneumococcal vaccine and influenza vaccine are indicated to prevent infection. However, use of live vaccines is not recommended in these immunocompromised patients. However, the newer recombinant zoster vaccine, unlike the earlier live-attenuated zoster vaccine, may be given to prevent herpes zoster.

Renal compromise can often be ameliorated with adequate hydration. Even patients with prolonged, massive Bence Jones proteinuria ( 10 to 30 g/day) may have intact renal function if they maintain urine output > 2000 mL/day. Dehydration combined with high-osmolar IV contrast may precipitate acute oliguric renal failure in patients with Bence Jones proteinuria. Plasma exchange may be effective in some cases.

Skeletal lesions require multiple supportive measures. Maintenance of ambulation and supplemental calcium and vitamin D help preserve bone density. Vitamin D levels should be measured at diagnosis and periodically, and dosing of vitamin D adjusted accordingly. Analgesics and palliative doses of radiation therapy (18 to 24 gray) can relieve bone pain. However, radiation therapy may cause significant toxicity and, because it suppresses bone marrow function, may impair the patient’s ability to receive cytotoxic doses of systemic chemotherapy.

Most patients, especially those with lytic lesions and generalized osteoporosis or osteopenia, should receive a monthly IV bisphosphonate (either pamidronate or zoledronic acid). Bisphosphonates reduce skeletal complications and lessen bone pain and may have an antitumor effect. For patients with potentially reversible renal failure resulting from myeloma but unrelated to hypercalcemia or with ongoing infusion reactions after bisphosphonate infusion, an option is monthly denosumab (given subcutaneously), which, unlike bisphosphonates, is not cleared by the kidneys and does not cause infusion reactions. Both bisphosphonates and densousmab may uncommonly cause osteonecrosis of the jaw. Maintaining excellent dental health and avoiding dental explants and implants are important to minimize the risk of this complication.

Treatment references

  • 1. Berenson J, Spektor T, Wang J: Advances in the Management of Multiple Myeloma. Journal of Community and Supportive Oncology 14(5):232–235, 2016.

  • 2. Goldschmidt H, Ashcroft J, Szabo Z, Garderet L: Navigating the treatment landscape in multiple myeloma: which combinations to use and when? Ann Hematol 98: 1–18, 2019. doi: 10.1007/s00277-018-3546-8

  • 3. Rajkumar SV, Kumar S: Multiple myeloma: Diagnosis and treatment. Mayo Clinic Proc 91(1):101-119, 2016. doi: 10.1016/j.mayocp.2015.11.007.

  • 4. Rajkumar SV: Myeloma today: Disease definitions and treatment advances. Am J Hematol 91(1):90-100, 2016. doi: 10.1002/ajh.24392.

Key Points

  • Malignant plasma cells produce monoclonal immunoglobulin and invade and destroy bone.

  • Expanding plasmacytomas and cytokine secretion cause multiple, discrete, osteolytic lesions (usually in the pelvis, spine, ribs, and skull) and diffuse osteoporosis; pain, fractures, and hypercalcemia are common.

  • Anemia and renal failure are common.

  • Amyloidosis develops in about 10%, typically patients who produce excess lambda light chains.

  • Do serum and urine protein electrophoresis followed by immunofixation, quantitative immunoglobulins, and measurement of serum free light chains.

  • Do bone marrow aspiration and biopsy.

  • Symptomatic patients and those with organ dysfunction should be treated with drug therapy, which may include corticosteroids, proteasome inhibitors, immunomodulatory agents, monoclonal antibodies, and chemotherapy drugs.

  • Stem cell transplantation is an option for stable patients, but newer, highly effective treatment options may make transplantation less often necessary.

Drugs Mentioned In This Article

Drug Name Select Trade
CYTOXAN (LYOPHILIZED)
Gammagard S/D
ZOMETA
VALCYTE
OZURDEX
TREANDA
POMALYST
REVLIMID
ZYLOPRIM
FAMVIR
ELITEK
DARZALEX
KYPROLIS
No US brand name
THALOMID
AREDIA
EMPLICITI
RAYOS
VELCADE
MIACALCIN
PROLIA
ALKERAN
ZOVIRAX
Ixazomib
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NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version

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