Plasma-derived extracellular vesicles miR-335-5p as potential diagnostic biomarkers for fusion-positive rhabdomyosarcoma.

BACKGROUND: Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma, with embryonal (ERMS) and alveolar (ARMS) representing the two most common histological subtypes. ARMS shows poor prognosis, being often metastatic at diagnosis. Thus, the discovery of novel biomarkers predictive of tumor aggressiveness represents one of the most important challenges to overcome and may help the development of tailored therapies. In the last years, miRNAs carried in extracellular vesicles (EVs), small vesicles of endocytic origin, have emerged as ideal candidate biomarkers due to their stability in plasma and their tissue specificity. METHODS: EVs miRNAs were isolated from plasma of 21 patients affected by RMS and 13 healthy childrens (HC). We performed a miRNA profile using the Serum/Plasma Focus microRNA PCR panels (Qiagen), and RT-qPCR for validation analysis. Statistically significant (p < 0.05) miRNAs were obtained by ANOVA test. RESULTS: We identified nine EVs miRNAs (miR-483-5p, miR-132-3p, miR-766-3p, miR-454-3p miR-197-3p, miR-335-3p, miR-17-5p, miR-486-5p and miR-484) highly upregulated in RMS patients compared to HCs. Interestingly, 4 miRNAs (miR-335-5p, miR-17-5p, miR-486-5p and miR-484) were significantly upregulated in ARMS samples compared to ERMS. In the validation analysis performed in a larger group of patients only three miRNAs (miR-483-5p, miR-335-5p and miR-484) were differentially significantly expressed in RMS patients compared to HC. Among these, mir-335-5p was significant also when compared ARMS to ERMS patients. MiR-335-5p was upregulated in RMS tumor tissues respect to normal tissues (p = 0.00202) and upregulated significantly between ARMS and ERMS (p = 0.04). Furthermore, the miRNA expression correlated with the Intergroup Rhabdomyosarcoma Study (IRS) grouping system, (p = 0.0234), and survival (OS, p = 0.044; PFS, p = 0.025). By performing in situ hybridization, we observed that miR-335-5p signal was exclusively in the cytoplasm of cancer cells. CONCLUSION: We identified miR-335-5p as significantly upregulated in plasma derived EVs and tumor tissue of patients affected by ARMS. Its expression correlates to stage and survival in patients. Future studies are needed to validate miR-335-5p as prognostic biomarker and to deeply elucidate its biological role.

Evaluating Circulating Biomarkers for Diagnosis, Prognosis, and Tumor Monitoring in Pediatric Sarcomas: Recent Advances and Future Directions.

Pediatric sarcomas present a significant challenge in oncology. There is an urgent need for improved therapeutic strategies for high-risk patients and better management of long-term side effects for those who survive the disease. Liquid biopsy is emerging as a promising tool to optimize treatment in these patients by offering non-invasive, repeatable assessments of disease status. Circulating biomarkers can provide valuable insights into tumor genetics and treatment response, potentially facilitating early diagnosis and dynamic disease monitoring. This review examines the potential of liquid biopsies, focusing on circulating biomarkers in the most common pediatric sarcomas, i.e., osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma. We also highlight the current research efforts and the necessary advancements required before these technologies can be widely adopted in clinical practice.

Survival and prognostic analysis of preoperative indicators in patients undergoing surgical resections with rhabdomyosarcoma.

Several preoperative blood and biochemical parameters are associated with postoperative survival in many kinds of tumors. The aim of this study is to study the predictive value of several routine preoperative blood and biochemical parameters on the prognosis patients with rhabdomyosarcoma (RMS).We retrospectively recruited 55 patients diagnosed with RMS and had surgery at West China Hospital, Sichuan University between January 2010 and December 2018. Baseline characteristics of the patients, tumor features, surgery details, and values of several examinations were extracted. A long-term follow-up was conducted by phone call. A novel statistical analysis was subsequently carried out to look for the relationship of preoperative parameters and patients' prognosis.The ROC analysis showed an area under curve (AUC) of 0.608, 0.620, 0.626, 0.591, and 0.518 for neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), monocyte to lymphocyte ratio (MLR), lactic dehydrogenase (LDH), and alkaline phosphatase (ALP) respectively, and the cut-off value of 2.843, 162.961, and 0.239 for NLR, PLR, and MLR respectively. The survival analysis showed that certain blood and biochemical parameters could cause differences in overall survival (OS) (P = .005 for NLR, P = .005 for PLR, and P = .007 for MLR) and progression free survival (PFS) (P = .029 for NLR, P = .008 for PLR, and P = .013 for MLR).Several preoperative blood and biochemical parameters are novel prognostic factors in RMS patients. Specifically, a higher NLR, PLR, and MLR value will predict a statistically shorter OS and PFS.In the future, surgeons should care more about NLR, PLR, and MLR values and several other parameters in patients' preoperative normal blood and biochemical tests to predict the postoperative conditions.

Non-Thermal Plasma Application in Tumor-Bearing Mice Induces Increase of Serum HMGB1.

The application of cold atmospheric plasma (CAP) in cancer therapy could be one of the new anticancer strategies. In the current work, we used cold atmospheric plasma jet for the treatment of cultured cells and mice. We showed that CAP induced the death of MX-7 mouse rhabdomyosarcoma cells with the hallmarks of immunogenic cell death (ICD): calreticulin and heat shock protein 70 (HSP70) externalization and high-mobility group box 1 protein (HMGB1) release. The intensity of HMGB1 release after the CAP treatment correlated directly with the basal extracellular HMGB1 level. Releasing from dying cells, HMGB1 can act as a proinflammatory cytokine. Our in vivo study demonstrated that cold atmospheric plasma induces a short-term two-times increase in serum HMGB1 level only in tumor-bearing mice with no effect in healthy mice. These findings support our hypothesis that CAP-dependent HMGB1 release from dying cancer cells can change the serum HMGB1 level. At the same time, we showed a weak cytokine response to CAP irradiation in healthy mice that can characterize CAP as an immune-safety physical antitumor approach.

Cell-Free DNA in Pediatric Rhabdomyosarcoma: Potential and Challenges.

Rhabdomyosarcoma is an aggressive solid tumor that may disseminate hematogenously giving metastasis which represents the most important prognostic factor. Chances of an effective cure in childhood cancer rely on the capacity to make an early and accurate diagnosis, detect metastatic disease or relapse, and predict the response to treatment.Liquid biopsy is a very promising blood test for cancer detection and noninvasive disease monitoring. This method has a great advantage to use blood and plasma, a more accessible biological material, quick and easy to obtain with minimal pain and risk for patients. In particular, circulating free DNA (cfDNA) represents a tumor biomarker detected in plasma that gives information on biology and genetic background of tumor.Moreover, cfDNA mutation detection could be a reliable method to monitor the efficacy of treatment and to discover novel targets for a personalized treatment in pediatric solid tumor. Here, we describe an optimized protocol to cfDNA isolation from small amount of plasma, as well as a method to assess the quantity and quality of cfDNA. Finally, we propose ddPCR as a reliable method to detect mutations at low frequency in cfDNA obtained from pediatric rhabdomyosarcoma samples.

Phase 2 trial of sorafenib in children and young adults with refractory solid tumors: A report from the Children's Oncology Group.

BACKGROUND: Sorafenib is an oral small molecule inhibitor of multiple kinases controlling tumor growth and angiogenesis. The purpose of the phase 2 study was to determine the response rate of sorafenib and gain further information on the associated toxicities, pharmacokinetics, and pharmacodynamics of sorafenib in children and young adults with relapsed or refractory tumors including rhabdomyosarcoma, Wilms tumor, hepatocellular carcinoma (HCC), and papillary thyroid carcinoma (PTC). PROCEDURE: Sorafenib, 200 mg/m(2) /dose, was administered every 12 hr continuously for 28 day cycles using a two-stage design in two primary strata (rhabdomyosarcoma and Wilms tumor) and two secondary strata (HCC and PTC). Correlative studies in consenting patients included determination of sorafenib steady state trough concentrations and assessments of VEGF and sVEGFR2. RESULTS: Twenty patients (median age of 11 years; range, 5-21) enrolled. No objective responses (RECIST) were observed in the 10 evaluable patients enrolled in each of the two primary disease strata of rhabdomyosarcoma and Wilms tumor. No patients with HCC or PTC were enrolled. Sorafenib was not associated with an excessive rate of dose-limiting toxicity (DLT). The mean ± SD steady state concentration during cycle 1 day 15 was 6.5 ± 3.9 µg/ml (n = 10). CONCLUSIONS: Sorafenib was well tolerated in children at 200 mg/m(2) /dose twice daily on a continuous regimen with toxicity profile and steady state drug concentrations similar to those previously reported. Single agent sorafenib was inactive in children with recurrent or refractory rhabdomyosarcoma or Wilms tumor.

Disruption of CXCR2-mediated MDSC tumor trafficking enhances anti-PD1 efficacy.

Suppression of the host's immune system plays a major role in cancer progression. Tumor signaling of programmed death 1 (PD1) on T cells and expansion of myeloid-derived suppressor cells (MDSCs) are major mechanisms of tumor immune escape. We sought to target these pathways in rhabdomyosarcoma (RMS), the most common soft tissue sarcoma of childhood. Murine RMS showed high surface expression of PD-L1, and anti-PD1 prevented tumor growth if initiated early after tumor inoculation; however, delayed anti-PD1 had limited benefit. RMS induced robust expansion of CXCR2(+)CD11b(+)Ly6G(hi) MDSCs, and CXCR2 deficiency prevented CD11b(+)Ly6G(hi) MDSC trafficking to the tumor. When tumor trafficking of MDSCs was inhibited by CXCR2 deficiency, or after anti-CXCR2 monoclonal antibody therapy, delayed anti-PD1 treatment induced significant antitumor effects. Thus, CXCR2(+)CD11b(+)Ly6G(hi) MDSCs mediate local immunosuppression, which limits the efficacy of checkpoint blockade in murine RMS. Human pediatric sarcomas also produce CXCR2 ligands, including CXCL8. Patients with metastatic pediatric sarcomas display elevated serum CXCR2 ligands, and elevated CXCL8 is associated with diminished survival in this population. We conclude that accumulation of MDSCs in the tumor bed limits the efficacy of checkpoint blockade in cancer. We also identify CXCR2 as a novel target for modulating tumor immune escape and present evidence that CXCR2(+)CD11b(+)Ly6G(hi) MDSCs are an important suppressive myeloid subset in pediatric sarcomas. These findings present a translatable strategy to improve the efficacy of checkpoint blockade by preventing trafficking of MDSCs to the tumor site.

Fibrocytes represent a novel MDSC subset circulating in patients with metastatic cancer.

Fibrocytes are hematopoietic stem cell-derived fibroblast precursors that are implicated in chronic inflammation, fibrosis, and wound healing. Myeloid-derived suppressor cells (MDSCs) expand in cancer-bearing hosts and contribute to tumor immune evasion. They are typically described as CD11b⁺HLA-DR⁻ in humans. We report abnormal expansions of CD11b⁺HLA-DR⁺ myeloid cells in peripheral blood mononuclear fractions of subjects with metastatic pediatric sarcomas. Like classical fibrocytes, they display cell surface α smooth muscle actin, collagen I/V, and mediate angiogenesis. However, classical fibrocytes serve as antigen presenters and augment immune reactivity, whereas fibrocytes from cancer subjects suppressed anti-CD3-mediated T-cell proliferation, primarily via indoleamine oxidase (IDO). The degree of fibrocyte expansion observed in individual subjects directly correlated with the frequency of circulating GATA3⁺CD4⁺ cells (R = 0.80) and monocytes from healthy donors cultured with IL-4 differentiated into fibrocytes with the same phenotypic profile and immunosuppressive properties as those observed in patients with cancer. We thus describe a novel subset of cancer-induced myeloid-derived suppressor cells, which bear the phenotypic and functional hallmarks of fibrocytes but mediate immune suppression. These cells are likely expanded in response to Th2 immune deviation and may contribute to tumor progression via both immune evasion and angiogenesis.

Vascular endothelial growth factor serum levels in children with newly diagnosed rhabdomyosarcoma.

BACKGROUND: The adverse prognostic impact of elevated levels of circulating Vascular Endothelial Growth Factor (VEGF) is described in several malignancies. However, no information is available in childhood rhabdomyosarcoma (RMS). In the present study, serum VEGF-A (sVEGF-A) was measured at diagnosis in a series of patients with RMS. PROCEDURE: sVEGF-A was assessed retrospectively in 17 newly diagnosed RMS patients. sVEGF-A concentrations were determined by quantitative enzyme-linked immunoabsorbent ELISA kit and their possible associations with age at diagnosis, gender, histology, primary site, primary size, Intergroup Rhabdomyosarcoma Study (IRS) post-surgical group, and outcome were investigated. RESULTS: sVEGF-A median value in patients with RMS was significantly higher than in controls: 499.0 pg/ml, range: 2,648.0 versus 301.5 pg/ml, range: 716.0 (P = 0.013). Although not statistically significant probably due to the limited number of patients, sVEGF-A median levels resulted higher in unfavorable primary sites (277.0 vs. 539.0 pg/ml; P = 0.31), and advanced groups (390.0 vs. 715.0; P = 0.29). Patients with shorter 5-year overall survival (OS) and 5-year progression-free survival (PFS) times also had higher sVEGF-A levels, although again the difference was not statistically significant (P = 0.18 and P = 0.22, respectively). CONCLUSIONS: Circulating VEGF is significantly increased in pediatric patients with newly diagnosed RMS. Further studies in larger series of RMS patients are needed to understand whether measurements of circulating VEGF might have a role in assessing prognosis and modulating treatment.

A phase 2 trial of trabectedin in children with recurrent rhabdomyosarcoma, Ewing sarcoma and non-rhabdomyosarcoma soft tissue sarcomas: a report from the Children's Oncology Group.

PURPOSE: To determine the toxicity, efficacy and pharmacokinetics of trabectedin given over 24h every 3 weeks to children with recurrent rhabdomyosarcoma, Ewing sarcoma, or non-rhabdomyosarcoma soft tissue sarcomas. PATIENTS AND METHODS: Trabectedin was administered as a 24-h intravenous infusion every 21 days. Two dose levels were evaluated (1.3 and 1.5mg/m(2)) for safety; efficacy was then evaluated using a traditional 2-stage design (10+10) at the 1.5mg/m(2) dose level. Pharmacokinetics (day 1 and steady state) were performed during cycle 1. RESULTS: Fifty patients were enrolled, eight patients at 1.3mg/m(2) and 42 at 1.5mg/m(2). Dose limiting toxicities (DLTs) in the dose finding component included fatigue and reversible GGT elevation in 1/6 evaluable patients at 1.3mg/m(2) and 0/5 at 1.5mg/m(2). Efficacy was evaluated in 42 patients enrolled at the 1.5mg/m(2) dose of whom 22% experienced reversible grade 3 or 4 toxicities that included AST, ALT, or GGT elevations, myelosuppression and deep venous thrombosis. One patient with rhabdomyosarcoma had a partial response and one patient each with rhabdomyosarcoma, spindle cell sarcoma and Ewing sarcoma had stable disease for 2, 3 and 15 cycles, respectively. CONCLUSION: Trabectedin is safe when administered over 24h at 1.5mg/m(2). Trabectedin did not demonstrate sufficient activity as a single agent for children with relapsed paediatric sarcomas.

Is the NBN gene mutation I171V a potential risk factor for malignant solid tumors in children?

NBN gene is considered as one of the low-to-moderate cancer susceptibility gene. At least 4 germline NBN mutations have been found in several malignancies in adults. In our studies, we observed the high incidence of germline mutation I171V of NBN gene in breast, colorectal, larynx cancer, and in multiple primary tumors. In this study, we would like to answer the question whether I171V germline mutation of NBN gene may constitute risk factor for solid tumors in children. The frequency of this mutation has been analyzed in patients with neuroblastoma (n=66), Wilms tumor (n=54), medulloblastoma (n=57), and rhabdomyosarcoma (n=82) hospitalized in Pediatric Oncology, Hematology and Bone Marrow Transplantation Department in the years between 1987 and 2010. About 2947 anonymous blood samples collected on Guthrie cards drawn from the newborn screening program of the Wielkopolska region have been used as controls. All the patients and controls came from the same geographical region. I171V mutation of the NBN gene has been observed in 5 controls. Among children with solid tumors only in 1 child with medulloblastoma I171V variant has been found. In conclusion, I171V germline mutation in contrary to adults cannot be considered as a risk factor for children malignancies. However, owing to low number of patients with solid tumors the possibility of a Type II error may exist.

Quantification of dimethyl-ifosfamide and its N-deschloropropylated metabolites in mouse plasma by liquid chromatography-tandem mass spectrometry.

Among antitumor oxazaphosphorine drugs, the prodrug ifosfamide (IFO) and its analogs require metabolic activation by specific liver cytochrome P450 (CYP) enzymes to become therapeutically active. New 7,9-dimethyl-ifosfamide analogs have shown greater cytotoxic activity than IFO, whereas side-chain oxidation still occurred leading to monochloroacetone after N-dechloropropylation. A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed and validated for the simultaneous quantitation of the prodrug 7S,9S-dimethyl-ifosfamide (diMeIFO) and its two inactive metabolites, N(2)- and N(3)-deschloropropyl-dimethylifosfamide (N(2)-DCP-diMeIFO and N(3)-DCP-diMeIFO) in mouse plasma. After protein precipitation with methanol, the analytes were separated by isocratic reversed-phase chromatography with (methanol/ammonium formate pH 5.5, 60:40, v/v) and detected by tandem mass spectrometry using multiple reaction monitoring of transitions ions m/z 289→168 for diMeIFO, m/z 213→168 for N(2)-DCP-diMeIFO, m/z 213→92 for N(3)-DCP-diMeIFO and m/z 261→154 for IFO (internal standard). The calibration curves were linear over the concentration range of 20-10,000ng/mL for the three analytes. Mean extraction recoveries from mouse plasma were 99, 96, 99 and 100% for diMeIFO, N(2)-DCP-diMeIFO, N(3)-DCP-diMeIFO and IFO, respectively. The lower limit of quantitation for diMeIFO and its metabolites was 20 ng/mL in 50 µL plasma. The method was accurate with calculated bias from -5.8 to 4.0% for diMeIFO, from -1.1 to 10.6% for N(2)-DCP-diMeIFO and from -6.9 to 9.8% for N(3)-DCP-diMeIFO, and precise with coefficients of variation lower than 6.8%, 7.8% and 14.3%, respectively. The assay was successfully applied to a preliminary pharmacokinetic study of diMeIFO and of its metabolites in mice.

Increased midkine serum levels in pediatric embryonal tumor patients.

Serum levels of midkine (MK), a heparin-binding growth factor, are elevated in adult cancer patients. We analyzed sera of pediatric tumor patients in comparison to a large number of children and adolescents without malignant disease. MK was studied in sera of 152 noncancer patients and 29 embryonal tumor patients (14 nephroblastoma, 10 neuroblastoma, and 5 rhabdomyosarcoma) using an enzyme-linked immunosorbent assay. Noncancer patients underwent elective surgical procedures or suffered from an endocrinologic disease. They had no evidence of inflammation or injury. MK serum levels were significantly higher in tumor patients (median 0.621 ng/mL) than in noncancer patients. About 86% of tumor patients were identified using a cut-off value of 0.176 ng/mL. MK values did neither correlate with tumor size nor with stage or histology, but decreased in half of the nephroblastoma patients after chemotherapy and surgery. MK values were found to be elevated in only 2 out of 5 rhabdomyosarcoma patients. MK may serve as an additional marker for the detection of pediatric embryonal tumors, but its clinical relevance for the evaluation of response to therapy needs further study.

A case of extremely chemoresistant pure pleomorphic rhabdomyosarcoma of the uterus associated with a high serum LDH level.

BACKGROUND: Pleomorphic rhabdomyosarcoma (RMS) of gynecologic origin is an exceedingly rare, highly malignant tumor. Only a few cases have been reported in the last decades. CASE REPORT: A 60-year-old postmenopausal woman presented with a high LDH level of unknown origin. Ultimately, she was diagnosed with pleomorphic RMS. She underwent total hysterectomy, bilateral salpingo-oophorectomy, left pelvic and paraaortic lymphadenectomy and partial omentectomy. Surgery was followed by systemic chemotherapy and pelvic irradiation. Unfortunately, the patient did not respond to treatment. Her disease course correlated with the fluctuation of plasma LDH levels. Ultimately she died within 20 months of the diagnosis. CONCLUSION: It is important to have better insight and to set a standard multimodal treatment for adult RMS. In addition, plasma LDH levels can be considered as a prognostic marker for RMS, particularly in advanced stage.

Flow cytometric phenotype of rhabdomyosarcoma bone marrow metastatic cells and its implication in differential diagnosis with neuroblastoma.

BACKGROUND: The goal of this study was to develop a flow cytometric (FCM) method for assessing the presence of metastatic cells in bone marrow (BM) and peripheral blood (PB) obtained from rhabdomysarcoma (RMS) patients. Myogenin (Myf4), a specific molecular RMS marker, was also investigated in the same samples. Since neuroblastoma (NB) metastasizes to the BM, the potential application of cytometry in differential diagnosis was explored. PATIENTS AND METHODS: CD45, CD56, CD90 and CD57 antibodies were used in 7 paired BM and PB samples (from 7 RMS stage IV patients at presentation), 23 BM samples (from 13 RMS stage I and II patients at presentation), and ten paired BM and PB samples taken at presentation and five BM samples taken at recurrence from 13 NB stage 4 patients. RESULTS: All seven BM samples from RMS stage IV (but not those from patients with localized disease) showed both the CD45- CD56+ phenotype and the Myf4 transcript. Four cases also showed CD90 and two CD57 positivity. Neither the CD45- CD56+ phenotype, nor Myf4 were recorded in the BM and PB samples from patients with localized disease. All the NB BM samples (15/15) showed the CD45- CD56+ CD90+ phenotype and 10/15 also showed CD57 positivity. Only 3/10 blood samples from the NB patients revealed tumor cells. CONCLUSION: CD45, CD56, CD90 and CD57 antibodies can be used in FCM for marrow metastasis detection in both, RMS and NB patients.

Are serum levels of CD44 relevant in children with pediatric sarcomas?

BACKGROUND: Variation in serum levels of CD44, which acts as an adhesion receptor involved in lymphocyte migration and binding, have been reported in some malignancies. The aim of this study is to compare serum levels of CD44 in children with sarcomas with those in healthy children. PROCEDURE: CD44 levels were measured by enzyme-linked immunosorbent assay (ELISA) in serum samples taken at diagnosis from 55 children with sarcomas and from 27 healthy children of similar age, sex, and socioeconomic status. RESULTS: There was no statistically significant difference between CD44 serum levels of children with sarcomas and those of healthy children. No significant difference was observed between CD44 serum levels of each patient group and those of control group (P > 0.05). There was no significant difference among CD44 serum levels of patient groups according to stage or outcome. CONCLUSIONS: In this study, serum CD44 levels were not found to be of value in the diagnosis or prognosis in children with sarcomas.

Changes in thyroid hormone state in children receiving chemotherapy.

OBJECTIVE: The concentrations of thyroid function determinants may change during severe illness. Our goal was to quantify their changes in children with cancer during chemotherapy, and to correlate them to clinical condition and type of drugs. DESIGN: During a 3-month period all patients admitted for chemotherapy to the paediatric oncology ward were evaluated for inclusion. Patients with brain tumours, neuroblastoma (cranio)spinal irradiation and use of dexamethasone before the first blood sample were excluded. MEASUREMENTS: Plasma concentrations of T4, T3, rT3, thyroxine-binding globulin (TBG), thyroglobulin (Tg), TSH, IGF-1, cortisol, PRL and physical well-being by means of questionnaires were measured before and during chemotherapy. RESULTS: In 19 children, 46 courses of chemotherapy and 123 plasma samples were analysed. During chemotherapy, mean concentrations of TSH, T3, Tg and cortisol decreased to 53, 67, 69 and 15% of the baseline value, respectively. Mean plasma rT3 increased to 217% of baseline. In 87% of all courses, one or more thyroid parameter(s) was aberrant. Furthermore, in 23 samples (19%) from 10 patients (53%), the concentration of IGF-1 was below the reference value (adjusted for sex and age). Small changes were seen in scores for clinical condition but none was related to a change in thyroid function determinant. Most changes in thyroid hormones could be attributed to using dexamethasone. CONCLUSIONS: These results demonstrate that, in children, thyroid hormone state changes significantly during chemotherapy, apparently not related to physical well-being but to the drugs administered. Future investigations should focus on the impact for patient care and possibilities of (preventive) intervention.

Unexpected interactions between nicotinamide and CPT-11 in a rhabdomyosarcoma tumor model.

We investigated the potential chemosensitizing effect of nicotinamide on CPT-11, and the relationship between nicotinamide and CPT-11, intratumoral drug uptake in syngeneic rhabdomyosarcoma tumors in rats. Pretreatment with nicotinamide, known to improve tumor oxygenation, perfusion and radiotherapy effect, only caused a minor increase in tumor growth delay. To our surprise, intratumoral uptake of CPT-11 and its active metabolite SN-38 decreased significantly between 19% and 43%. This discrepancy suggests that the potential chemosensitizing effect of nicotinamide, seen in other studies, is based on a direct effect on tumor cells rather than on an increased delivery of anticancer drugs. A second finding is that plasma levels of CPT-11 and SN-38 respectively increase and decrease after nicotinamide exposure, suggesting inhibition of carboxylesterase, which is necessary for the conversion of CPT-11 to its active metabolite SN-38. Great care is required when combining nicotinamide with anticancer drugs, since unexpected pharmacokinetic and pharmacodynamic alterations might occur.

Assessment of cardiotoxicity during haemopoietic stem cell transplantation with plasma brain natriuretic peptide.

Cardiac failure is a known complication of haemopoietic stem cell transplantation (HSCT) and is often difficult to diagnose as patients may have multiple medical problems. Since brain natriuretic peptide (BNP) is largely a hormone of cardiac ventricular origin and is released early in the course of ventricular dysfunction, we have examined the value of serial plasma BNP levels for detecting cardiac failure in patients undergoing cytotoxic conditioning for HSCT. Fifteen patients undergoing HSCT were evaluated (10 undergoing autologous HSCT; five undergoing allogeneic HSCT). BNP was measured by radioimmunoassay prior to therapy and weekly for 5 weeks. Seven patients had a significant rise in BNP level (above a previously established threshold of 43 pmol/l associated with cardiac failure), occurring 1-4 weeks post commencement of conditioning. In three of these patients, cardiac failure was subsequently diagnosed clinically 3, 9 and 23 days after a BNP level of 43 pmol/l had been detected. These three patients had the highest peak BNP levels for the group and in each case elevation in BNP level occurred for a period exceeding 1 week. Although numbers were relatively small, a BNP >43 pmol/l was significantly associated with the inclusion of high-dose cyclophosphamide in the preparative regimen (P = 0.02). BNP levels showed no relationship to febrile episodes. In conclusion, these results show that plasma BNP may be used as a marker for early detection of cardiac dysfunction in patients undergoing HSCT, particularly if levels are increased for periods exceeding 1 week. Measurement of BNP during HSCT may be helpful in patients at risk of cardiac failure, in complex clinical situations and in monitoring the cardiotoxicity of preparative regimens.