Gunderson, Heidi D

Abstract Introduction: Currently, the most extensively tested treatments for immunoglobulin light chain amyloidosis (AL) are high dose melphalan followed by autologous stem cell transplantation (ASCT) and melphalan and dexamethasone (MDex). A recent randomized controlled trial comparing the two regimens showed MDex is at least equivalent if not superior to ASCT. Most patients with symptomatic systemic AL have a low plasma cell load; however, approximately 30% have bone marrow plasmacytosis greater than 20% but do not meet criteria for multiple myeloma with significant anemia or lytic bone disease. This leads to the speculation that the plasma cell biology (and therefore outcomes) might differ between low and high plasma cell burden AL. We undertook this study to address whether these two standard regimens are equally effective in AL patients with low and high plasma cell burden. Methods: Patients with confirmed AL treated with MDex were recruited for this study. Some of the patients treated were not ASCT candidates while others were eligible but favored MDex. Hematologic response was defined as 50% reduction in serum M-protein or 90% reduction in urine M-protein if one was present, otherwise a 50% reduction in serum free light chain levels was used. Organ involvement was defined according to the Consensus Opinion from the 10th International Symposium on Amyloid and Amyloidosis. Patients were separated into a high and a low marrow plasma cells (PC) group based on their percentage of bone marrow plasma cells. Cutoff for the bone marrow plasmacytosis was calculated using receiver-operator characteristic (ROC) curve. Overall survival (OS) and progression free survival (PFS) were compared using Kaplan-Meier method. OS was also calculated for 342 AL patients treated with ASCT for comparison. Results: Seventy-three patients with AL received MDex between 05/01 and 05/07. Median follow-up was 16.8 months. At the time of the study, 42.5% had died. Calculating for OS and PFS, the best cutoff for bone marrow plasmacytosis was found to be 20%. In our cohort, 28.8% had >20% bone marrow plasmacytosis. Age (64.8 yr vs 61.0 yr, p = 0.61) and sex (81% male vs 63.4% male, p = 0.13) were similarly distributed between patients with high and low PC. Cardiac troponin T (cTnT) was also comparable between the 2 groups (0.03 ng/ml (high) vs 0.06 ng/ml (low), p = 0.41). Cardiac involvement were similar between high and low PC groups (78.9% vs 85.7% respectively, p = 0.49) but renal involvement was less common in the high PC group (70.6% vs 38.1%, p = 0.01). No differences were noted in the gastrointestinal and neurological involvement. Patients with high PC received a median of 4 cycles of MDex vs 5 in the low PC group (p = 0.68). Hematologic response was achieved in 75% of patients with high PC and 54.9% of the low’s (p = 0.11). A significant difference was noted in the PFS and OS between the 2 groups. The PFS and OS were 13.5m and 15.3m, respectively for patients with high PC but neither was reached in those with < 20% plasmacytosis (p=0.02 and p = 0.03 respectively). In the multivariate analysis, hematologic response, cardiac involvement and plasmacytosis >20% were independent predictors of PFS and OS. To determine if plasmacytosis had the same affect on survival of ASCT treated patients, 342 patients were analyzed. No relationship between OS and % of plasmacytosis was found. Conclusion: Our study suggests that ASCT and MDex may not be equivalent for all AL patients. Even though hematologic response rates were similar, patients with plasmacytosis >20% had a worse OS and PFS when treated with MDex. This disparity in survival was not evident in patients treated with ASCT. This effect was independent of cardiac involvement. If confirmed, this could have a significant impact on the choice of therapy for AL patients. The best therapy may be determined by the extent of marrow plasmacytosis, with higher plasma cells favoring high dose therapy.

Abstract Abstract 2574 Rasburicase is a recombinant urate oxidase approved for the prevention of tumor lysis syndrome (TLS). In adults, the recommended dose is 0.2 mg/kg intravenously daily up to 5 days. For a 75 kg person, the cost is over $5100. Given the vast reduction of uric acid seen with this dose, it may be possible to use a reduce dose. The aim of this study is to evaluate the effectiveness of 0.1 mg/kg dose vs the recommended dose in the prevention of TLS. Between October of 2003 and February of 2009, all patients with a hematologic or oncologic diagnosis who received rasburicase were reviewed. Rasburicase had been dosed at either 0.1 mg/kg (low dose) or 0.2 mg/kg (standard dose) due to variations in practice among the practitioners. Rasburicase was given on the first day of chemotherapy and repeated as necessary. Renal insufficiency was defined by 0.5 mg/dl rise in serum creatinine (Scr) within 7 days of chemotherapy initiation. The need for dialysis was recorded separately. Labs were performed pretreatment and usually daily after chemotherapy until electrolytes stabilized. A multivariate analysis using pretreatment labs was performed to determine risk factors for renal insufficiency or failure. During the study period, 125 patients received rasburicase. Fifty-five patients received low dose rasburicase and 70 received the standard dose. The diagnoses are listed in Table 1. Lactate dehydrogenase (LDH) was similar between the two groups (604 U/l in low dose vs 665 U/l in standard dose, p = 0.69). Additional doses were required in 14.5% of the low dose patients vs 21.4% of the standard dose patients, p = 0.36. Renal insufficiency was noted only in the standard dose patients 7.4% vs 0%, p = 0.04. Rates of dialysis were similar between low dose patients 7.3% vs 17.4% in the standard dose patients, p = 0.10. Dialysis was often initiated for hyperkalemia and hyperphosphatemia. Only 12.5% were started for elevation in Scr. Uric acid reduction was higher in the standard dose patients (90.4 ± 15.8%) as compared with low dose patients (82.0 ± 19.0%, p = 0.01). Pretreatment Scr, uric acid and phosphorus levels were found to be significant variable for dialysis but only uric acid was found to be significant in the multivariate analysis. Pretreatment uric acid was a risk factor for dialysis (p < 0.001) but not for renal insufficiency (p = 0.24). Our results suggest that low dose rasburicase may be as effective as 0.2 mg/kg. While high dose rasburicase was more effective at reducing uric acid, it did not reduce the need for dialysis because dialysis was often needed for hyperkalemia and hyperphosphatemia which rasburicase did not affect. Despite bias, our results suggest low dose rasburicase may be a viable alternative and definitely support further study into its use. The potential savings could be enormous given that it would be $2550 per patient. Table 1. Baseline diagnosis of 125 patients with TLS Diagnosis Low dose Standard dose dose Diffuse large B-cell lymphoma 13 17 Chronic lymphocytic leukemia 3 12 Multiple myeloma 7 5 Non-Hodgkin's lymphoma 4 7 Acute myeloid leukemia 4 7 Burkitt's lymphoma 3 4 T-cell lymphoma 4 3 B-cell lymphoma 5 1 Solid Tumor 1 5 Myelofibrosis 3 2 Mantle cell lymphoma 3 1 Amyloidosis 0 2 Blast crisis in acute leukemia 1 1 B-cell lymphoproliferative disorder 0 1 Chronic myeloproliferative disorder 0 1 Follicular mixed lymphoma 0 1 Hodgkin's lymphoma 1 0 undifferentiated 1 0 Lymphoreticular myeloid malignancy 1 0 Post-transplant lymphoproliferative disorder 0 1 Splenic marginal cell lymphoma 1 0 Waldenstrom macroglobulinemia 1 0 Total 55 70 Disclosure: No relevant conflicts of interest to declare.

Without adequate safety measures, oral chemotherapy can lead to undetected dosing errors. The Mayo Clinic launched a project to ensure that all capecitabine and temozolomide prescriptions receive an independent double check.

The study looks at the high cost of new treatments for chronic lymphocytic leukemia and calls for the consideration of a standardized and transparent method to determine the price of new drugs based on comparative effectiveness.

Objective: To describe a case of acquired Fanconi syndrome after treatment with capecitabine, irinotecan, and bevacizumab. Case Summary: A 77-year-old female with metastatic colon cancer presented with vomiting and diarrhea. The patient had been diagnosed with stage IIIC (T3, N2, M0) colon cancer 18 months earlier and was initially treated with FOLFOX6 (regimen of oxaliplatin, fluorouracil, and leucovorin) after her hemicolectomy. She was switched to a capecitabine/oxaliplatin regimen after 4 cycles due to central access problems. She did well until 10 months after her cancer diagnosis, when metastasis was discovered. She was started on reduced doses of capecitabine, irinotecan, and bevacizumab. After her eleventh cycle, she presented to the hospital with the above symptoms. Laboratory test results showed hypokalemia, hypocalcemia, hypophosphatemia, and hypouricemia. The patient had not been started on any new medications other than chemotherapy for over 1 year. The electrolyte derangements were new, since the patient had laboratory values checked every 3 weeks. Despite daily intravenous replacements, the electrolyte abnormalities persisted. Laboratory evaluations demonstrated the presence of euglycemic glucosuria and a high fractional excretion of phosphorus in the setting of hypophosphatemia. Fanconi syndrome was confirmed by demonstration of aminoaciduria. Discussion: Fanconi syndrome is a disorder characterized by proximal tubular dysfunction resulting in electrolyte wasting. In the acquired form, medications and multiple myeloma are the most common causes. Based on the Naranjo probability scale, a drug was the probable cause of Fanconi syndrome in our patient. However, because multiple drugs were involved, it was not possible to determine which one was the culprit. Conclusions: This is the first case of Fanconi syndrome reported after the administration of capecitabine, irinotecan, and bevacizumab. More studies are needed to confirm this association.