Using RB1 mutations to assess minimal residual disease in metastatic retinoblastoma.

To assess complete remission before subjecting nongermline metastatic retinoblastoma patients to an autologous peripheral stem cell transplant, we tested for patient-specific retinoblastoma tumor suppressor gene (RB1) mutant alleles in cerebrospinal fluid (CSF) and bone marrow. In 1 child with CSF and 1 with bone marrow metastases, allele-specific polymerase chain reaction (AS-PCR) detected the biallelic RB1 mutations specific to their tumors. The tumor of Child A was homozygous for R251X, and in Child B, it was homozygous for R358X. In Child A, the R251X mutation was detected in mutant controls diluted to 1:12,800 but not in CSF samples, corroborating clinical remission after chemotherapy. In Child B's bone marrow, AS-PCR for R358X was strongly positive at the detection of relapse, and subsequent bone marrow samples corroborated clinical remission after chemotherapy. No mutant tumor RB1 alleles were detected in their harvested peripheral blood stem cells. Both children were deemed suitable candidates for supralethal-dosage consolidation chemotherapy followed by autologous peripheral stem cell rescue of the bone marrow aimed at curing their metastatic retinoblastoma. When Child A recurred, the mutant tumor RB1 allele was detected 3.5 months before conventional pathology detected retinoblastoma tumor cells in the CSF. Assaying tumor-specific RB1 mutations complements cytological and immunohistochemical assessment of retinoblastoma involvement of CSF and bone marrow. Tumor cells can be detected in numbers lower than possible by conventional methods. An early diagnosis of relapse may allow an early institution of new therapy. A prospective international multicenter trial of the rare patients with metastatic retinoblastoma would assess the role of molecular monitoring in surveillance for minimal residual disease and recurrence.

Anti-thrombin III in the management of hematopoietic stem-cell transplantation-associated toxicity.

OBJECTIVE: To describe the evidence assessing the use of anti-thrombin III (AT-III) in the management of toxicity associated with hematopoietic stem-cell transplantation (HSCT)-conditioning regimens. DATA SOURCES: Clinical literature was accessed through conference proceedings, EMBASE, the Cochrane database, and MEDLINE (1966-December 2003). STUDY SELECTION AND DATA EXTRACTION: Case reports, small case series, case-control and cohort studies, and randomized controlled trials of AT-III in HSCT were evaluated. Publications examining AT-III use in the non-HSCT setting were also explored. Key search terms included AT-III, transplantation, and veno-occlusive disease (VOD). DATA SYNTHESIS: Severe VOD and ensuing multiple organ dysfunction is associated with high mortality in HSCT. A low AT-III level has been shown to correlate with the development of organ dysfunction. Phase II trials, case series, and one small, randomized, placebo-controlled study suggest a benefit when AT-III therapy is instituted early in the course of VOD/multiple organ dysfunction syndrome. In all of these reports, AT-III use was devoid of adverse events. CONCLUSIONS: Although further studies are needed to ascertain the optimal target level, method, and duration of administration, AT-III is still a viable alternative for the treatment of severe VOD and ensuing multiple organ dysfunction.