Delayed hematopoietic recovery after auto-SCT in patients receiving arsenic trioxide-based therapy for acute promyelocytic leukemia: a multi-center analysis

A potential link between arsenic (ATO)-based therapy and delayed hematopoietic recovery after autologous hematopoietic SCT (HSCT) for acute promyelocytic leukemia (APL) has previously been reported. We retrospectively reviewed the clinical histories of 58 patients undergoing autologous HSCT for APL at 21 institutions in the United States and Japan. Thirty-three (56%) of the patients received ATO-based therapy prior to stem cell collection. Delayed neutrophil engraftment occurred in 10 patients (17%): 9 of the 10 patients (90%) received prior ATO (representing 27% of all ATO-treated patients), compared with 1 of the 10 patients (10%) not previously treated with ATO (representing 4% of all ATO-naïve patients; P<0.001). Compared with ATO-naïve patients, ATO-treated patients experienced significantly longer times to ANC recovery (median 12 days vs 9 days, P<0.001). In multivariate analysis, the only significant independent predictor of delayed neutrophil engraftment was prior treatment with ATO (hazard ratio 4.87; P<0.001). Of the available stem cell aliquots from APL patients, the median viable post-thaw CD34+ cell recovery was significantly lower than that of cryopreserved autologous stem cell products from patients with non-APL AML. Our findings suggest that ATO exposure prior to CD34+ cell harvest has deleterious effects on hematopoietic recovery after autologous HSCT.

CVP alternating with fludarabine (CVP/F) chemotherapy prior to idiotype vaccination for follicular lymphoma (FL)

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Background: Reducing the tumor burden prior to vaccination facilitates an effective immune response (IR) against the idiotype in FL. In this context, we evaluated the efficacy and toxicity of a novel cytoreductive regimen, CVP/F. Methods: Newly diagnosed, advanced stage FL patients (pt) were treated with CVP (cyclophosphamide 400 mg/m2 PO d1–5, vincristine 2 mg d 1, prednisone 100 mg/m2 d1–5) alternating with F (25 mg/m2 IV d1–5) every 21 days for 2 cycles beyond best response (maximum 8). Pt judged to be cytoreduced adequately were vaccinated monthly × 5 with idiotype protein made from their FL. Results: Among 34 enrolled pt, median age was 45 years (yr), and FLIPI scores were: 18% low, 71% intermediate and 12% high. 38% pt had grade 1 and 62% had grade 2 FL. There were no toxic deaths or opportunistic infections. With 233 cycles (117 CVP and 116 F) given to 33 evaluable pt, neutropenic fever occurred in 7 cycles (3%). 20 cycles (17%) of CVP and 29 cycles (25%) of F were dose reduced for leukopenia. 18 pt (53%) achieved a CR (16) or CRu (2), and 13 pt (38%) had a PR. 22 pt (65%) treated with CVP/F proceeded to vaccination; 10 additional pt (29%) were vaccinated after secondary chemotherapy was given for further cytoreduction. At median follow-up of 11.2 yr, 15-yr overall survival (OS) was 85%. Two of 5 deaths occurred without lymphoma progression. TTF (time to treatment failure = second treatment, relapse, death) at 11 yr was 38%. Anti-idiotype antibody and T cell IR were seen in 44% and 31% pt, respectively. There were no differences in TTF or OS according to IR. Conclusions: CVP/ F was effective in advanced FL, comparing favorably with our historical experience with CVP in terms of CR rate, proportion proceeding to vaccination, TTF and OS after vaccination. This favorable outcome may have been due to the novel alternating CVP/F cytoreductive regimen, idiotype vaccination or both. The idiotype vaccine is now being tested in phase III trials. The CVP/F regimen also warrants further evaluation.

No significant financial relationships to disclose.