Detection of cell-free microbial DNA using a contaminant-controlled analysis framework

BACKGROUND

The human microbiome plays an important role in cancer. Accumulating evidence indicates that commensal microbiome-derived DNA may be represented in minute quantities in the cell-free DNA of human blood and could possibly be harnessed as a new cancer biomarker. However, there has been limited use of rigorous experimental controls to account for contamination, which invariably affects low-biomass microbiome studies.

RESULTS

We apply a combination of 16S-rRNA-gene sequencing and droplet digital PCR to determine if the specific detection of cell-free microbial DNA (cfmDNA) is possible in metastatic melanoma patients. Compared to matched stool and saliva samples, the absolute concentration of cfmDNA is low but significantly above the levels detected from negative controls. The microbial community of plasma is strongly influenced by laboratory and reagent contaminants introduced during the DNA extraction and sequencing processes. Through the application of an in silico decontamination strategy including the filtering of amplicon sequence variants (ASVs) with batch dependent abundances and those with a higher prevalence in negative controls, we identify known gut commensal bacteria, such as Faecalibacterium, Bacteroides and Ruminococcus, and also other uncharacterised ASVs. We analyse additional plasma samples, highlighting the potential of this framework to identify differences in cfmDNA between healthy and cancer patients.

CONCLUSIONS

Together, these observations indicate that plasma can harbour a low yet detectable level of cfmDNA. The results highlight the importance of accounting for contamination and provide an analytical decontamination framework to allow the accurate detection of cfmDNA for future biomarker studies in cancer and other diseases.

γδ T Cells in Merkel Cell Carcinomas Have a Proinflammatory Profile Prognostic of Patient Survival

Merkel cell carcinomas (MCC) are immunogenic skin cancers associated with viral infection or UV mutagenesis. To study T-cell infiltrates in MCC, we analyzed 58 MCC lesions from 39 patients using multiplex-IHC/immunofluorescence (m-IHC/IF). CD4⁺ or CD8⁺ T cells comprised the majority of infiltrating T lymphocytes in most tumors. However, almost half of the tumors harbored prominent CD4/CD8 double-negative (DN) T-cell infiltrates (>20% DN T cells), and in 12% of cases, DN T cells represented the majority of T cells. Flow cytometric analysis of single-cell suspensions from fresh tumors identified DN T cells as predominantly Vδ2^- γδ T cells. In the context of γδ T-cell inflammation, these cells expressed PD-1 and LAG3, which is consistent with a suppressed or exhausted phenotype, and CD103, which indicates tissue residency. Furthermore, single-cell RNA sequencing (scRNA-seq) identified a transcriptional profile of γδ T cells suggestive of proinflammatory potential. T-cell receptor (TCR) analysis confirmed clonal expansion of Vδ1 and Vδ3 clonotypes, and functional studies using cloned γδ TCRs demonstrated restriction of these for CD1c and MR1 antigen-presenting molecules. On the basis of a 13-gene γδ T-cell signature derived from scRNA-seq analysis, gene-set enrichment on bulk RNA-seq data showed a positive correlation between enrichment scores and DN T-cell infiltrates. An improved disease-specific survival was evident for patients with high enrichment scores, and complete responses to anti-PD-1/PD-L1 treatment were observed in three of four cases with high enrichment scores. Thus, γδ T-cell infiltration may serve as a prognostic biomarker and should be explored for therapeutic interventions.See related Spotlight on p. 600.

Evolution of late-stage metastatic melanoma is dominated by aneuploidy and whole genome doubling

Although melanoma is initiated by acquisition of point mutations and limited focal copy number alterations in melanocytes-of-origin, the nature of genetic changes that characterise lethal metastatic disease is poorly understood. Here, we analyze the evolution of human melanoma progressing from early to late disease in 13 patients by sampling their tumours at multiple sites and times. Whole exome and genome sequencing data from 88 tumour samples reveals only limited gain of point mutations generally, with net mutational loss in some metastases. In contrast, melanoma evolution is dominated by whole genome doubling and large-scale aneuploidy, in which widespread loss of heterozygosity sculpts the burden of point mutations, neoantigens and structural variants even in treatment-naïve and primary cutaneous melanomas in some patients. These results imply that dysregulation of genomic integrity is a key driver of selective clonal advantage during melanoma progression.

Clinical, FDG-PET and molecular markers of immune checkpoint inhibitor response in patients with metastatic Merkel cell carcinoma

BACKGROUND

Metastatic Merkel cell carcinoma (mMCC) is an aggressive neuroendocrine malignancy of the skin with a poor prognosis. Immune checkpoint inhibitors (ICIs) have shown substantial efficacy and favorable safety in clinical trials.

METHODS

Medical records of patients (pts) with mMCC treated with ICIs from August 2015 to December 2018 at Peter MacCallum Cancer Centre in Australia were analyzed. Response was assessed with serial imaging, the majority with FDG-PET/CT scans. RNA sequencing and immunohistochemistry for PD-L1, CD3 and Merkel cell polyomavirus (MCPyV) on tumor samples was performed.

RESULTS

23 pts with mMCC were treated with ICIs. A median of 8 cycles (range 1 to 47) were administered, with treatment ongoing in 6 pts. Objective responses (OR) were observed in 14 pts (61%): 10 (44%) complete responses (CR) and 4 (17%) partial responses (PR). Median time to response was 8 weeks (range 6 to 12) and 12-month progression-free survival rate was 39%. Increased OR were seen in pts aged less than 75 (OR 80% vs 46%), no prior history of chemotherapy (OR 64% vs 50%), patients with an immune-related adverse event (OR 100% vs 43%) and in MCPyV-negative tumors (OR 69% vs 43%). Pts with a CR had lower mean metabolic tumor volume on baseline FDG-PET/CT scan (CR: 35.7 mL, no CR: 187.8 mL, p=0.05). There was no correlation between PD-L1 positivity and MCPyV status (p=0.764) or OR (p=0.245). 10 pts received radiation therapy (RT) during ICI: 4 pts started RT concurrently (OR 75%, CR 50%), 3 pts had isolated ICI-resistant lesions successfully treated with RT and 3 pts with multisite progression continued to progress despite RT. Overall, 6 pts (26%) had grade 1-2 immune-related adverse events.

CONCLUSION

ICIs showed efficacy and safety in mMCC consistent with trial data. Clinical and imaging predictors of response were identified.

The survivorship experience for patients with metastatic melanoma on immune checkpoint and BRAF-MEK inhibitors

PURPOSE

Immune checkpoint inhibitors (ICI) and BRAF and MEK inhibitors (BMi) have improved survival in metastatic melanoma (MM). However, the experience of long-term responders remains undescribed. This study characterised survivorship issues faced by long-term responders to ICI or BMi.

METHODS

Patients with MM, aged ≥ 18 years old, ≥ 6 months post-ICI or BMi initiation with an objective response or stable disease. A 72-question survey assessed physical and psychological effects, impact on lifestyle, access to information, satisfaction with care, and availability of supports.

RESULTS

One hundred and five of 120 (88%) patients completed the survey (ICI 69/BMI 36). For the ICI cohort, 39 (57%) were receiving ongoing treatment, 17 ceased due to toxicity and 13 due to a sustained response. For the BMi cohort, 31 (85%) were receiving ongoing treatment, 4 ceased due to toxicity and 1 due to a sustained complete response. At data cut-off on 18 December 2018, median PFS (range) was 2.5 years (1.3-8.5) for ICI and 3.1 years (0.6-7.3) for BMi. Long-term toxicities included dry/itchy skin (ICI 51, 74%/ BMi 25, 69%), arthralgias (ICI 30, 58%/ BMi 23, 64%) and fatigue (ICI 62, 90%/ BMi 33, 92%). Psychological morbidity was common, including anxiety awaiting results (ICI 50, 72%/ BMi 29, 81%), fear of melanoma recurring or progressing (ICI 56, 81%/ BMi 31, 86%) or death (ICI 44, 64%/ BMi 26, 72%).

CONCLUSION

MM survivors experience chronic treatment toxicities and frequently report psychological concerns.

IMPLICATIONS FOR CANCER SURVIVORS

Survivors may benefit from discussions regarding long-term toxicities and tailored psychological supports.

Clinical and FDG-PET markers of immune checkpoint inhibitor (ICI) response in patients with metastatic Merkel cell carcinoma (mMCC)

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Background: mMCC is a rare, highly aggressive neuroendocrine cancer with a poor prognosis. ICIs have favourable efficacy and safety in clinical trials. We outline single centre experience utilising ICIs in mMCC. Methods: Medical records of patients (pts) with mMCC treated with ICIs from Aug 2015 to Dec 2018 at Peter MacCallum Cancer Centre in Australia were retrospectively analysed. RNA sequencing and immunohistochemistry for PD-L1, CD3 and Merkel cell polyomavirus (MCPyV) on tumor samples were performed. Baseline tumor volumes and responses were assessed with FDG-PET scans using the Hicks criteria. Results: 23 pts with mMCC were treated with ICIs. Pt characteristics are summarised in Table. A median of 8 cycles (range 1 to 47) were administered, with treatment ongoing in 7 pts. Objective responses (OR) were observed in 14 pts (61%); 10 (44%) complete metabolic responses (CMR) and 4 (17%) partial metabolic responses (PMR). Median time to response was 9 weeks (range 4 to 11) and 12-month progression-free survival (PFS) rate was 32%. Increased OR were seen in pts aged less than 75 (OR 8/10, 80% vs 46%), no prior history of chemotherapy (OR 10/14, 71% vs 44%), pts with an immune-related adverse event (irAE) (OR 6/6, 100% vs 47%) and in MCPyV negative pts (OR 9/11, 82% vs 50%). Pts with a CMR had lower mean-tumor volume on baseline FDG-PET scan (CMR: 35.7mL, no CMR: 187.8mL, p value 0.05). 10 pts received radiation (RT) during ICI: 4 pts started RT concurrently (OR 75%, CMR 50%), 3 pts had isolated ICI-resistant lesions successfully treated with RT and 3 pts with multisite progression continued to progress despite RT. 6 pts (26%) had a Grade 1-2 irAE. Conclusions: ICIs showed efficacy and safety consistent with trial data. Younger age, negative MCPyV status, no prior chemotherapy, lower baseline FDG-PET tumor volume and irAEs are potentially associated with better responses. [Table: see text]

Prediction and monitoring of relapse in stage III melanoma using circulating tumor DNA

BACKGROUND

The advent of effective adjuvant therapies for patients with resected melanoma has highlighted the need to stratify patients based on risk of relapse given the cost and toxicities associated with treatment. Here we assessed circulating tumor DNA (ctDNA) to predict and monitor relapse in resected stage III melanoma.

PATIENTS AND METHODS

Somatic mutations were identified in 99/133 (74%) patients through tumor tissue sequencing. Personalized droplet digital PCR (ddPCR) assays were used to detect known mutations in 315 prospectively collected plasma samples from mutation-positive patients. External validation was performed in a prospective independent cohort (n = 29).

RESULTS

ctDNA was detected in 37 of 99 (37%) individuals. In 81 patients who did not receive adjuvant therapy, 90% of patients with ctDNA detected at baseline and 100% of patients with ctDNA detected at the postoperative timepoint relapsed at a median follow up of 20 months. ctDNA detection predicted patients at high risk of relapse at baseline [relapse-free survival (RFS) hazard ratio (HR) 2.9; 95% confidence interval (CI) 1.5-5.6; P = 0.002] and postoperatively (HR 10; 95% CI 4.3-24; P < 0.001). ctDNA detection at baseline [HR 2.9; 95% CI 1.3-5.7; P = 0.003 and postoperatively (HR 11; 95% CI 4.3-27; P < 0.001] was also associated with inferior distant metastasis-free survival (DMFS). These findings were validated in the independent cohort. ctDNA detection remained an independent predictor of RFS and DMFS in multivariate analyses after adjustment for disease stage and BRAF mutation status.

CONCLUSION

Baseline and postoperative ctDNA detection in two independent prospective cohorts identified stage III melanoma patients at highest risk of relapse and has potential to inform adjuvant therapy decisions.

Lower serum fibroblast activation protein shows promise in the exclusion of clinically significant liver fibrosis due to non-alcoholic fatty liver disease in diabetes and obesity

Non-alcoholic fatty liver disease (NAFLD) is common in diabetes and obesity but few have clinically significant liver fibrosis. Improved risk-assessment is needed as the commonly used clinical-risk algorithm, the NAFLD fibrosis score (NFS), is often inconclusive.

AIMS

To determine whether circulating fibroblast activation protein (cFAP), which is elevated in cirrhosis, has value in excluding significant fibrosis, particularly combined with NFS.

METHODS

cFAP was measured in 106 with type 2 diabetes who had transient elastography (Cohort 1) and 146 with morbid obesity who had liver biopsy (Cohort 2).

RESULTS

In Cohort 1, cFAP (per SD) independently associated with median liver stiffness (LSM) ≥ 10.3 kPa with OR of 2.0 (95% CI 1.2-3.4), p=0.006. There was 0.12 OR (95% CI 0.03-0.61) of LSM ≥ 10.3 kPa for those in the lowest compared with the highest FAP tertile (p=0.010). FAP levels below 730 pmol AMC/min/mL had 95% NPV for LSM ≥ 10.3 kPa and reclassified 41% of 64 subjects from NFS 'indeterminate-risk' to 'low-risk'. In Cohort 2, cFAP (per SD), associated with 1.7 fold (95% CI 1.1-2.8) increased odds of significant fibrosis (F ≥ 2), p=0.021, and low cFAP reclassified 49% of 73 subjects from 'indeterminate-risk' to 'low-risk'.

CONCLUSIONS

Lower cFAP, when combined with NFS, may have clinical utility in excluding significant fibrosis in diabetes and obesity.

Abstract 2499: Single agent activity of checkpoint kinase inhibitor PF-477736, in a MYC-driven lymphoma model

CHK1 and CHK2 are protein kinases that function as effectors of cell cycle checkpoint arrest following DNA damage. Small molecule inhibitors with specificity for CHK1 such as PF-477736 (Blasina et al, 2008 Mol Cancer Ther 7:2394) and others with specificity for CHK1 and CHK2, are currently in phase 1 clinical evaluation in combination with chemotherapeutic agents known to induce DNA damage. We therefore hypothesized that inhibitors of CHK1/CHK2 may have single agent activity in tumours with oncogene-induced DNA damage.

Cell lines derived from Eμ-MYC driven murine lymphomas display intrinsic DNA damage detected by γH2AX foci staining. Within 2 hours of 500nM PF-477736 treatment, a dramatic increase in the intensity of γH2AX staining and proportion of cells with γH2AX staining, was observed in all Eμ-MYC lines. An increase in mitotic cells detected by expression of phospho-Histone3, was also observed in all Eμ-MYC lines with a high proportion displaying features of aberrant mitosis, demonstrating inhibition of the S and/or G2/M checkpoints resulting in premature entry to mitosis. Early apoptosis was detected in 6 separate Eμ-MYC lines expressing functional p53, following treatment in vitro (&gt;50% Annexin V positive cells 4 hrs after 500nM PF-477736). Subsequent cell death assessed as the proportion of PI positive cells, was observed in all cell lines expressing functional p53 (IC50 200-500nM at 16 hrs).

Enforced expression of anti-apoptotic protein Bcl-2 by retroviral transduction abrogated cell death at up to 3μM PF-477736. Two separate Eμ-MYC lines expressing spontaneously arising mutant forms of p53, and three separate Eμ-MYC lines derived on a p53 null background, were relatively insensitive to PF-477736 (IC50&gt;1μM at 16hrs), indicating that functional p53 is necessary to mediate apoptosis/death following accumulation of DNA damage due to CHK1 inhibition. Treatment with AZD7762 a CHK1/2 inhibitor, also resulted in death of Eμ-MYC lines in vitro, (IC50 200nM-2μM at 16 hrs), however the variation in sensitivity could not be attributed to p53 status.

Treatment of C57Bl/6 mice transplanted with an Eμ-MYC line expressing functional p53, resulted in a dramatic increase in the proportion of apoptotic/dead cells in the established lymphomas within 6 hours following 20mg/kg PF-477736 i.p. A significant decrease in the wbc of 5 mice, from an average 48.2×106 wbc/ml pre-treatment to 31.8×106 at 16 hours post PF-477736 (P=0.0053), compared to vehicle treated mice (51.1×106 pre-treatment and 60.4×106 post-treatment), together with a lower average spleen weight of the PF-477736 treated mice (0.52g) compared to vehicle treated mice (0.68g), was observed.

We propose that checkpoint kinase inhibitors will be beneficial as therapeutic agents able to specifically exploit tumours containing intrinsic DNA damage that are reliant on checkpoints for maintenance of genomic integrity, such as in “MYC-driven cancers”.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2499.

Imaging with FLT-PET demonstrates that PF-477736, an inhibitor of CHK1 kinase, overcomes a cell cycle checkpoint induced by gemcitabine in PC-3 xenografts

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Background: The development of strategies to monitor the molecular and cellular response to novel agents that target the cell cycle is vital to provide proof of mechanism and biological activity of these compounds. The protein kinase CHK1 is activated following DNA damage in the S and G2-phases of the cell cycle and mediates cell cycle arrest. In vitro studies demonstrate that inhibition of CHK1 can overcome cell cycle arrest induced by DNA damage and enhance cytotoxic activity of DNA damaging agents. In vivo studies show that combining DNA damaging agents with a CHK1 inhibitor potentiates antitumor activity. We hypothesize that functional imaging with 18F-fluorine-L-thymidine (FLT), a PET-tracer where tumor uptake is maximal in the S and G2 phases of the cell cycle can be used to non-invasively monitor the induction and therapeutic inhibition of a cell cycle checkpoint in vivo. Methods: Nude mice harbouring PC-3 xenografts were treated with vehicle controls, gemcitabine, the CHK1-inhibitor PF-477736 or gemcitabine + PF-477736. FLT-PET scans were performed and tumors harvested for ex-vivo biomarkers to assess S-phase, M-phase and DNA-repair. Results: Gemcitabine induced a 8.3 ±0.8 fold increase in tumoral uptake of FLT at 21 hours that correlated with a 3.3 ±0.2-fold increase in thymidine kinase activity and S-phase arrest as demonstrated by BrdU incorporation and elevated expression of cyclin-A. Treatment with PF-477736 at 17 hours after gemcitabine abrogated the early FLT-flare at 21 hours by 82% (p<0.001). This was associated with both an increased fraction of cells in mitosis and G1-phase of the cell cycle as determined by phos-histone H3 and flow cytometry. Furthermore, the combination of gemcitabine and PF-477736 enhanced DNA damage as measured by phos-gamma-H2AX and significantly delayed tumor growth when compared to tumors treated with gemcitabine alone. Conclusion: These data clearly indicate that the CHK1-inhibitor PF-477736 can overcome the cell cycle checkpoint induced by gemcitabine and increase associated DNA damage in tumors in-vivo. The PET studies indicate that functional imaging with FLT-PET is a promising strategy to monitor responses to therapeutic agents that target cell cycle checkpoints.

[Table: see text]

Diffusion limited hypoxia estimated by vascular image analysis: comparison with pimonidazole staining in human tumors

PURPOSE

To assess diffusion limited hypoxia in human tumors using image analysis of vasculature and to compare it with the bioreductive marker pimonidazole as an independent method.

MATERIALS AND METHODS

To set up the method, nine rectal adenocarcinomas and ten squamous cell carcinomas were analyzed. To validate the method, ten squamous cell carcinomas of the cervix were analyzed from patients who were injected with pimonidazole and biopsied approximately 24 h later. Sections of the rectal and esophageal tumors were stained for vasculature, while cervix tumor sections were double stained for vasculature and pimonidazole. Tumor areas were delineated on digitized images, and the proportion of tumor tissue greater than a fixed distance from the nearest blood vessel (called diffusion limited fraction, DLF) was then calculated. The proportion of tumor area stained for pimonidazole was also measured.

RESULTS

There was a wide variation between tumors in both the vascular-derived DLF and in the pimonidazole-stained fraction. Average DLFs varied between 1.5 and 92% for different tumors, with significant differences between them. The area stained by pimonidazole was significantly smaller than DLF for all tumors. The correlation between pimonidazole area and DLF was significant in three of seven tumors containing > or = 3 images. When images from all tumors (n=123) were analyzed together, the correlation was highly significant (r=0.47, P<0.0001).

CONCLUSION

The vascular derived DLF correlates significantly with pimonidazole staining, but there was large scatter. Both methods may underestimate perfusion limited hypoxia.

Hepatocellular hypoxia-induced vascular endothelial growth factor expression and angiogenesis in experimental biliary cirrhosis

We tested the potential role of vascular endothelial growth factor (VEGF) and of fibroblast growth factor-2 (FGF-2) in the angiogenesis associated with experimental liver fibrogenesis induced by common bile duct ligation in Sprague-Dawley rats. In normal rats, VEGF and FGF-2 immunoreactivities were restricted to less than 3% of hepatocytes. One week after bile duct ligation, hypoxia was demonstrated by the immunodetection of pimonidazole adducts unevenly distributed throughout the lobule. After 2 weeks, hypoxia and VEGF expression were detected in >95% of hepatocytes and coexisted with an increase in periportal vascular endothelial cell proliferation, as ascertained by Ki67 immunolabeling. Subsequently, at 3 weeks the density of von Willebrand-labeled vascular section in fibrotic areas significantly increased. Semiquantitative reverse transcription polymerase chain reaction showed that VEGF(120) and VEGF(164) transcripts, that correspond to secreted isoforms, increased within 2 weeks, while VEGF(188) transcripts remained unchanged. FGF-2 mainly consisting of a 22-kd isoform, according to Western blot, was identified by immunohistochemistry in 49% and 100% of hepatocytes at 3 and 7 weeks, respectively. Our data provide evidence that in biliary-type liver fibrogenesis, angiogenesis is stimulated primarily by VEGF in response to hepatocellular hypoxia while FGF-2 likely contributes to the maintenance of angiogenesis at later stages.

Diagnostic ultrasound

Significant growth in the technology and clinical application of diagnostic ultrasound has occurred over the past decade. The non cardiac aspects of these recent developments are briefly discussed and illustrated.

Misonidazole with dexamethasone rescue: an escalating dose toxicity study

Neurotoxicity induced by misonidazole (MISO) and desmethylmisonidazole (DMM) has become the dose limiting factor in clinical work. In 1981, we reported a preliminary study suggestive that Dexamethasone (DEXA) does have a protective effect against peripheral neuropathies (PN) resulting from toxicity of misonidazole. Furthermore, in that study we have observed that DEXA did not alter the plasma pharmacokinetics of misonidazole. We are presently investigating the use of DEXA (2 mg t.i.d. during treatment), with escalating doses of MISO in an attempt to modify its neurotoxicity. To date, 16 patients have been registered to receive total doses of MISO ranging from 13.5 to 17.5 gm/M2 given in 9 equally divided doses over 3 weeks. DEXA, 2 mg t.i.d. is given 3 days prior to the first dose and continues for the duration of therapy. All patients receive palliative radiation. No toxicity was seen at the total dose of 13.5 gm/M2. One grade I PN occurred in the first four patients receiving 15.5 gm/M2. Six additional patients were entered at this dose level and no further incidence of PN was observed. Patients are being entered at the next step of 17.5 gm/M2.

High dose misonidazole with dexamethasone rescue: a possible approach to circumvent neurotoxicity

With a view to modifying misonidazole (MISO) neurotoxicity, we initiated a randomized clinical study to assess a possible drug interaction and toxicity protection when dexamethasone (DXM) is administered concomittantly with MISO. The ongoing study consists of: 1. Pharmacokinetic evaluation; 2. Assessment of toxicity. Fourteen patients undergoing radiation therapy for different types of malignant neoplasia (excluding brain tumors) have been randomized to receive either MISO alone, or DXM one week prior and during treatment with MISO. Five of seven patients receiving MISO alone developed peripheral neuropathies while only one out of 7 patients that received MISO with DXM coverage developed a transient and mild neuropathy. Pharmacokinetic evaluation of MISO in plasma and urine of those patients receiving DXM has shown no evidence of drug interaction. It is postulated that the mechanism of action of DXM is at the nerve cell membrane level, restoring and stabilizing cell surface properties. In future studies we will investigate the use of DXM with increasing doses of MISO above the recommended maximum dose of 12 gm/m2, hoping to achieve a higher tumor tissue level of MISO while avoiding unacceptable toxicity. The effect of Allopurinol on the plasma kinetics of MISO was studied in four additional patients, observing also no evidence of drug interaction.

Pharmacokinetic interaction of BCNU and misonidazole in humans

Although considerable laboratory in vitro and in vivo evidence is now available suggesting that misonidazole (MISO) enhances chemotherapy tumor responses, experience with human tumors is limited. Further, the mechanism of this enhancement is not definitely known. One possible mechanism is that MISO alters the pharmacokinetics of the chemotherapeutic agent, vice versa or both. We studied a group of patients with recurrent malignant gliomas, following radiotherapy. After proven recurrence, they were treated with i.v. BCNU in combination with oral MISO in an 8 week cycle. Our aims were: 1. To obtain a second remission; 2. To assess the toxicity of this combination; 3. To assess the plasma pharmacokinetics of each drug alone and in combination. Six patients entered the protocol. Four of six patients obtained either a partial or subpartial response. Prolonged moderate myelosuppression was observed in 2/6 patients after 3 cycles; 2/6 patients experienced seizures after the first cycle of chemotherapy for the first time in the course of their disease. The plasma pharmacokinetic data indicates no evidence of a MISO-BCNU drug interaction.

Type V hyperlipoproteinaemia: a family study

Family screening for hyperlipoproteinaemia was undertaken when a patient presented with myocardial infarction in association with Type V hyperlipoproteinaemia. The clinical features of this unusual form of hyperlipoproteinaemia are discussed together with its frequency in the general population and in relatives of affected patients.