Primary AL amyloidosis is the most common form of systemic amyloidosis, and amyloid deposits are formed by degradation of immunoglobulin light chain derived from abnormal M protein detectable in serum with no association of multiple myeloma (1, 2). In this form of amyloidosis the kidneys are consistently and severely involved from the early phase of illness, frequently showing the nephrotic syndrome and renal dysfunction. Although several chemotherapeutic regimens have been tried in order to suppress the amyloidogenic M protein produced by plasma cell dyscrasia in hematopoietic tissues, it remains difficult to improve the prognosis of this disease. Here, we report a patient with primary AL amyloidosis who mainly suffered from renal amyloid deposition with nephrotic syndrome, and focus on his successful treatment.

In May 2000 a 54-year-old man with no remarkable past history noticed edema in his bilateral lower extremities with a weight gain of 10 kg during the previous one year, but did not visit a doctor. He was admitted to a neighboring hospital in February 2001 because his edema had gradually worsened and extended to his face. Based on his clinical symptoms together with laboratory data showing proteinuria, hypoalbuminemia and hyperlipidemia, he was diagnosed as having nephrotic syndrome. Electrophoresis detected IgG λ type M protein in his serum and urinary excretion of Bence Jones protein, but there was no abnormal morphology in the bone marrow. Histopathological examinations of biopsied renal tissues demonstrated amyloid deposits (Fig. 1A, B). Primary AL amyloidosis was confirmed as the disease underlying the nephrotic syndrome, and he was then referred to our hospital for treatment in July 2001.

On admission at the end of August he showed no abnormal findings on physical examination except for mild edema in the bilateral pretibial regions. Blood chemistry revealed hypoproteinemia with total protein at 4.7 g/dl (normal 6.8–8.3 g/dl) and albumin at 2.1 g/dl (normal 4.2–5.1 g/dl), and hyperlipidemia with total cholesterol at 251 mg/dl (normal 120–220 mg/dl) and triglyceride at 195 mg/dl (normal 30–150 mg/dl). Blood urea nitrogen (BUN) and creatinine were 19 mg/dl (normal 9–22 mg/dl) and 1.0 mg/dl (normal 0.6–1.0 mg/dl), respectively, and creatinine clearance was 68.9 ml/min (normal 80–130 ml/min). Urinalysis showed strongly positive proteinuria with daily protein excretion of 4.1 g. Hematology, serum electrolytes and indices of liver function were all normal. Although evaluations of serum immunoglobulin showed a slightly decreased level of IgG (633 mg/dl, normal 800–2,000 mg/dl) with normal values of IgA (73 mg/dl, normal 70–470 mg/dl) and IgM (52 mg/dl, normal 40–350 mg/dl), serum protein electrophoresis demonstrated a monoclonal peak in the γ-zone (Fig. 2A). Immunofixation confirmed IgG λ type M protein in serum and Bence Jones protein in urine (Fig. 2A). On aspiration biopsy the slightly hypocellular bone marrow specimen contained 2.5% plasma cells (normal 0.4–2.6%) with no abnormal morphology. Occult blood was negative in stool with both the orthotolidine and immunological methods. In the endoscopic examination almost normal mucosa was seen throughout the gastroduodenal portion, but histopathology showed amyloid deposits mainly in the submucosal perivascular areas of the biopsied gastroduodenal specimens (Fig. 1C). On immunohistochemistry these amyloid deposits were specifically immunolabeled with an anti-Aλ antibody (Fig. 1D). Aspiration biopsy of abdominal fat tissue also revealed deposition of amyloid. The electrocardiogram (ECG) showed low voltage in the limb leads and QS pattern in the right precordial leads. ^99mTc-pyrophosphate myocardial scintigram revealed diffuse positive uptake in both ventricles. No abnormal findings were seen either on chest X-ray and echocardiogram or in peripheral nerve conduction velocities.

From September 2001 the patient received two courses of VAD (vincristine 0.4 mg/day and doxorubicin 9 mg/m²/day by continuous infusion on days 1–4, and dexamethasone 40 mg/day by infusion on days 1–4, 9–12 and 17–20; all were repeated four weeks later) (Fig. 3). At the end of the second course of VAD, etoposide was given intravenously at 200 mg/m²/day for 4 days. The dose was chosen to guarantee transient neutropenia without severe thrombocytopenia. Then, to mobilize hematopoietic stem cells in the peripheral blood, granulocyte-colony stimulating factor (G-CSF) was administered subcutaneously at 10 μg/kg/day in two doses every day. At leukapheresis over two days 8×10⁶/kg CD34-positive stem cells were collected and cryopreserved at –80ºC until autologous peripheral blood stem cell transplantation (auto-PBSCT). The values of creatinine and BUN increased gradually in parallel with a decrease in creatinine clearance and urinary volume during and after the two courses of VAD and the administration of etoposide, but he showed no other complications. After this treatment M protein became undetectable in both serum and urine (Fig. 2B).

Six weeks after the infusion of etoposide, melphalan was administered intravenously at 140 mg/m² over two days with oral antimicrobial prophylaxis using ciprofloxacin and amphotericin B, and the cryopreserved stem cells were infused 72 hours later just after thawing. Hematological recovery was supported by 5 μg/kg/day of G-CSF. High-dose melphalan treatment and auto-PBSCT were tolerated well apart from moderate nausea and grade 1 mucositis according to the criteria of the Japan Clinical Oncology Group (3). Full hematological recovery was observed one month after the auto-PBSCT. M protein remained undetectable in both urine and serum (Fig. 2C), and urinary excretion of protein was reduced, resulting in an increased serum level of albumin (2.9 g/dl). The leg edema disappeared and the patient was discharged in the middle of May 2002.

The prognosis of primary systemic AL amyloidosis is in general bad with a median survival time of around 13 months after diagnosis, because vital organs such as heart and kidneys are most frequently involved from the early phase of the illness (2). In the kidneys amyloid is first deposited in the mesangium of the glomerulus and later extends along the basement membrane, leading to various renal manifestations, including nephrotic syndrome, renal failure, nephrogenic diabetes insipidus, adult Fanconi's syndrome and renal vein thrombosis (1, 2). The nephrotic syndrome as seen in this patient is the most common of these manifestations, and usually results in a poor prognosis (2). In general the degree of proteinuria does not necessarily correlate with the extent of amyloid deposition in the kidney (2). Nevertheless, this patient was considered to already have subclinical renal dysfunction due to amyloidosis on admission to our hospital, because an increase in creatinine and BUN developed in parallel with a decrease in creatinine clearance soon after beginning the VAD therapy. In addition to the renal involvement, his heart was probably affected based on the ECG findings and a positive shadow on the ^99mTc-pyrophosphate myocardial scintigram (4, 5). Considering that amyloid deposits were present in multiple vital organs, including the heart, kidneys and the gastrointestinal tract, the prognosis of this patient was thought to be serious.

Since amyloidogenic M protein is produced from plasma cell dyscrasia in the hematopoietic tissues, effective chemotherapy directed at this abnormal pathology is necessary to suppress the amyloid deposition. Although the most common chemotherapy for primary AL amyloidosis has been intermittent administration of oral melphalan and prednisolone, the efficacy of this treatment is apparently insufficient in terms of an improvement in the prognosis (6–8). Several therapeutic trials using either interferon-α, high-dose corticosteroids or several combinations of cytostatics have been employed for primary AL amyloidosis based upon evidence that these drugs are effective for multiple myeloma (9–11). Among them, repeated VAD therapy showed a fairly good effect in reducing M protein in serum, although complete remission of illness was reported to be quite rare (11). During the past few years more intensive chemotherapy using high-dose melphalan or cyclophosphamide followed by auto-PBSCT has been used in patients with this disease, and has shown a promising therapeutic effect (12–17). Several reports have shown that the rate of complete remission in the production of M protein reached around 60% or more (12, 17). This therapy is, of course, more risky than other chemotherapeutic regimens in patients with amyloidosis-induced dysfunction in multiple vital organs (18, 19). Recently, it has been reported that the performance status and degree of cardiac involvement are important as potentially fatal risk factors after high-dose melphalan with auto-PBSCT in patients with AL amyloidosis (20). Because this patient was still in his fifties and showed a good performance status and no abnormal findings on echocardiogram, he was considered to be eligible for this intensive treatment. In Japan this therapy has not been widely employed for primary AL amyloidosis, and this is the first clinical report of a patient successfully treated in this manner.

In performing intensive chemotherapy there were two critical points to be considered in this patient. One was the degree of organ dysfunction and the extent of amyloid deposition. Considering the probable involvement of the heart, cyclophosphamide could not be used because of its high toxicity for myocardium. In the pretreatment for mobilization of stem cells, therefore, etoposide was employed as an alternative agent, though cyclophosphamide might be preferable with respect to its ability to reduce abnormal plasma cells in bone marrow. When administering melphalan, dose reduction according to renal function was considered to be unnecessary because it has a very short half-life in serum with a low toxicity for the heart and kidneys (21). It was given to this patient at a high dose of 140 mg/m², which has been commonly used to ablate pathogenetic plasma cells together with hematopoietic stem cells. The other critical point was that a relapse might occur after auto-PBSCT if pathogenetic plasma cells contaminated the hematopoietic stem cells collected by leukaphesis. Allogeneic stem cell transplantation is, of course, superior to auto-PBSCT for preventing relapse, but this therapy is generally not acceptable for primary AL amyloidosis at the present time because of many possible serious complications, including graft versus host disease (22–25). The relapse rate after auto-PBSCT is around 10% or less according to previous reports (12, 15). To reduce the possibility of relapse in this patient, we gave two courses of VAD and high-dose intravenous administration of etoposide before mobilization of hematopoietic stem cells. VAD therapy is superior to intermittent administration of melphalan and prednisolone as a pretreatment for auto-PBSCT because of the rapid reduction of pathogenetic plasma cells and absence of negative effects on mobilization of hematopoietic stem cells (22).

As a result of two courses of VAD and subsequent high-dose melphalan followed by auto-PBSCT, this patient showed a decrease in daily protein excretion in urine, and M protein became undetectable in both serum and urine. These results suggest that this intensive chemotherapy might be effective for amyloid-induced nephrotic syndrome itself as well as suppressing pathogenetic plasma cells. Although the nephrotic syndrome ascribed to primary AL amyloidosis has long been considered incurable, intensive chemotherapy, including high-dose melphalan followed by auto-PBSCT, might become a promising therapeutic approach to this amyloid-related renal disease.