O-177 Long-term follow up to assess criteria for ovarian tissue cryopreservation for fertility preservation in young women and girls with cancer

Study question

Do the Edinburgh selection criteria correctly identify females, diagnosed with cancer under 18 years old, at high risk of future premature ovarian insufficiency (POI)?

Summary answer

Patient assessment using these criteria accurately identifies those at risk of POI. Ovarian tissue cryopreservation with future transplantation can be offered, providing future fertility options.

What is known already

Cancer treatments can be gonadotoxic and future fertility and reproductive health should be considered at the time of diagnosis and treatment planning. Correct identification of patients at high risk allows appropriate discussion of fertility preservation with ovarian tissue cryopreservation (OTC) and future transplantation. The Edinburgh selection criteria have been proposed as a tool to identify those patients at high risk.

However, the surgical procedure is not without risk and reproductive outcomes remain uncertain in girls. Therefore, long-term follow up of reproductive function is crucial to ensure that this treatment strategy is offered appropriately.

Study design, size, duration

All females diagnosed with cancer less than 18 years old, in South East Scotland, between 01/01/96 and 30/10/20 were included. They were assessed using the Edinburgh selection criteria and offered OTC, if appropriate. Ongoing long-term follow up of reproductive outcomes has been undertaken for the whole patient cohort to detect those who develop POI.

Participants/materials, setting, methods

A total of 639 eligible patients were identified from the Cancer registry and their electronic records reviewed. Reproductive function was assessed by the presence of menstruation, pregnancy, hormonal measurements, evidence of puberty or diagnosis of POI. Patients on hormonal contraception (other than for the treatment of POI) were considered unsuitable for analysis.

Data were analysed using the Kaplan Meier method, with POI as the event, and the Cox proportional hazards model to calculate hazard ratios.

Main results and the role of chance

Of the 639 patients diagnosed with cancer during the study period, those deceased before age 12 years old (n = 73) or under 12 years old (n = 134) at the date of analysis were excluded; also excluding those on hormonal contraception (n = 9) gave a study population of 423.

Data were analysed including those with unknown reproductive outcomes (n = 143), assuming they did not have POI. A subgroup analysis excluding these patients was also performed.

Mean age at diagnosis and analysis was 8.8 years and 22.5 years respectively.

OTC was offered to 37 patients, 26 of whom underwent the procedure. Nine patients developed POI (24.3%). Of the 386 not offered OTC, 11 developed POI (2.85%). The hazard ratio for developing POI was 8.8 (CI 3.6-21).

Excluding the patients with unknown outcomes (n = 143) left a study population of 280. Within this group, 9 of 29 offered OTC developed POI (31.0%) versus 11 of 251 not offered OTC (4.4%); hazard ratio 8.2 (CI 3.4-20).

In the group offered OTC, all cases of POI developed after the primary treatment. In those not offered OTC, POI developed after secondary treatment for disease relapse in 5 patients (45.5%).

Limitations, reasons for caution

A significant number of patients had unknown reproductive outcomes; this is likely to reflect a lack of recording of normal menstrual function in oncology/haematology clinics but may have biased the analysis. The duration of follow up is also short for some patients, highlighting the need for further follow up.

Wider implications of the findings

The overall prevalence of POI after childhood cancer is low, but the Edinburgh selection criteria are a robust tool for selecting those at high risk at the time of diagnosis, who can be offered OTC. However, many patients had incomplete information on current reproductive status, which should be assessed routinely.

Trial registration number

N/A

Can intensity of long-term follow-up for survivors of childhood and teenage cancer be determined by therapy-based risk stratification?

OBJECTIVE

To determine the feasibility of therapy-based, risk-stratified follow-up guidelines for childhood and teenage cancer survivors by evaluating adverse health outcomes in a survivor cohort retrospectively assigned a risk category.

DESIGN

Retrospective cohort study.

SETTING

Tertiary level, single centre, paediatric cancer unit in South East Scotland.

PARTICIPANTS

All children and teenagers diagnosed with cancer (<19 years) between 1 January 1971 and 31 July 2004, who were alive more than 5 years from diagnosis formed the study cohort. Each survivor was retrospectively assigned a level of follow-up, based on their predicted risk of developing treatment-related late effects (LEs; levels 1, 2 and 3 for low, medium and high risk, respectively). Adverse health outcomes were determined from review of medical records and postal questionnaires. LEs were graded using the Common Terminology Criteria for Adverse Event, V.3.

RESULTS

607 5-year survivors were identified. Risk stratification identified 86 (14.2%), 271 (44.6%) and 250 (41.2%) as levels 1, 2 and 3 survivors, respectively. The prevalence of LEs for level 1 survivors was 11.6% with only one patient with grade 3 or above toxicity. 35.8% of level 2 survivors had an LE, of whom 9.3%, 58.8%, 18.5%, 10.3% and 3% had grades 1, 2, 3, 4 and 5 toxicity, respectively. 65.2% of level 3 survivors had LE, of whom 5.5% (n=9), 34.4% (n=56), 36.2% (n=59), 22.1% (n=36) and 1.8% (n=3) had grades 1, 2, 3, 4 and 5 toxicity, respectively.

CONCLUSIONS

Therapy-based risk stratification of survivors can predict which patients are at significant risk of developing moderate-to-severe LEs and require high-intensity long-term follow-up. Our findings will need confirmation in a prospective cohort study that has the power to adjust for all potentially confounding variables.

Survivors of childhood cancer lost to follow-up can be re-engaged into active long-term follow-up by a postal health questionnaire intervention

Lifelong long-term follow-up (LTFU) is recommended for all survivors of childhood cancer. National guidelines recommend risk-stratified levels of follow-up by a multidisciplinary team, in an age-appropriate environment. Many survivors do not participate in long-term follow-up.

OBJECTIVE

To re-engage childhood cancer survivors lost to follow-up in late effects programmes by means of postal questionnaire.

POPULATION AND METHODS

Retrospective cohort study of all children (<19 years) diagnosed with cancer in a single institution in the UK between 1971 and 2003. All lost to follow-up survivors (not seen in clinic >2 years) were sent a postal health and well-being questionnaire.

RESULTS

831 patients were diagnosed with childhood cancer between 1971 and 2003, with 575 long-term survivors (overall survival rate 69%). Information was available on 550 survivors (males 290 (53%), median age (range) at review 18.8 (5.4-44.2) years and at diagnosis 5.0 (0.0-18.8) years, and disease free survival (range) was 10.8 (1.0-37.4) years. Of the 550 survivors, 256 (46%) were lost to follow-up. 99 (39%) of lost to follow-up survivors returned completed postal questionnaires (58% female). 45% of responders reported at least one late effect, 36% mild-moderate, and 8% severe-life threatening. 19% reported two or more late effects. 74% of all childhood cancer survivors are now in active follow-up.

CONCLUSIONS

Almost half (46%) of all long-term survivors of childhood cancer are lost to follow-up, Postal follow-up is an effective means of re-engaging more than one third of survivors of childhood cancer in active long-term follow-up, half of whom had at least one late effect.

The forkhead transcription factor FOXL2 is expressed in somatic cells of the human ovary prior to follicle formation

Interactions between germ cells and surrounding somatic cells are central to ovarian development as well as later function. Disruption of these interactions arising from abnormalities in either cell type can lead to premature ovarian failure (POF). The forkhead transcription factor FOXL2 is a candidate POF factor, and mutations in the FOXL2 gene are associated with syndromic and non-syndromic ovarian failure. Foxl2-deficient mice display major defects in primordial follicle activation with consequent follicle loss, and earlier roles in gonadal development and sex determination have also been suggested. However, despite its importance no data presently exist on its expression in the developing human ovary. Expression of FOXL2 mRNA was demonstrated in the human fetal ovary between 8 and 19 weeks gestation, thus from soon after sex determination to primordial follicle development. Expression in the ovary was higher after 14 weeks than at earlier gestation weeks and was very low in the fetal testis at all ages examined. Immunolocalization revealed FOXL2 expression to be confined to somatic cells, both adjacent to germ cells and those located in the developing ovarian stroma. These cells are the site of action of oocyte-derived activin signalling, but in vitro treatment of human fetal ovaries with activin failed to reveal any regulation of FOXL2 transcription by this pathway. In summary, the expression of FOXL2 in somatic cells of the developing human ovary before and during follicle formation supports a conserved and continuing role for this factor in somatic/germ cell interactions from the earliest stages of human ovarian development.

Inhibition of cholesteryl ester transfer protein by substituted dithiobisnicotinic acid dimethyl ester: involvement Of a critical cysteine

SC-71952, a substituted analog of dithiobisnicotinic acid dimethyl ester, was identified as a potent inhibitor of cholesteryl ester transfer protein (CETP). When tested in an in vitro assay, the concentration of SC-71952 required for half-maximal inhibition was 1 microm. The potency of SC-71952 was enhanced 200-fold by preincubation of the inhibitor with CETP, and was decreased 50-fold by treatment with dithiothreitol. Analogs of SC-71952 that did not contain a disulfide linkage were less potent, did not display time dependency, and were not affected by dithiothreitol treatment. Kinetic and biochemical characterization of the inhibitory process of CETP by SC-71952 suggested that the inhibitor initially binds rapidly and reversibly to a hydrophobic site on CETP. With time, the bound inhibitor irreversibly inactivates CETP, presumably by reacting with one of the free cysteines of CETP. Liquid chromatography/mass spectroscopy (LC/MS) analyses of tryptic digests of untreated or SC-71952-inactivated CETP was used to identify which cysteine(s) were potentially involved in the time-dependent, irreversible component of inactivation by the inhibitor. One disulfide bond, Cys143-Cys184, was unaffected by treatment with the inhibitor. Inactivation of CETP by SC-71952 correlated with a progressive decrease in the abundance of free Cys-13 and Cys-333. Conversion of Cys-13 to alanine had no effect on the rapid reversible component of inactivation by SC-71952. However, it abolished the time-dependent enhancement in potency seen with the inhibitor when using wild-type CETP. These data indicate that Cys-13 is critical for the irreversible inactivation of CETP by SC-71952 and provides support for the structural model that places Cys-13 near the neutral lipid-binding site of CETP.

Electrospray/tandem mass spectrometry for quantitative analysis of lipid remodeling in essential fatty acid deficient mice

A method utilizing electrospray ionization coupled with tandem mass spectrometry was developed as a facile and rapid method to identify and quantify lipid remodeling in vivo. Electrospray/tandem mass spectrometric analyses were performed on lipids isolated from liver tissue and resident peritoneal cells from essential fatty acid sufficient and deficient mice. Essential fatty acid deficiency was chosen as the paradigm to evaluate the methodology because it epitomizes the most extreme dietary means of altering fatty acid composition of virtually all cellular lipid species. Qualitative and quantitative changes were measured in the phospholipid and cholesterol ester species directly in the chloroform/methanol lipid extract without any prior chromatographic separation. Lipid remodeling in liver and peritoneal cells from essential fatty acid deficient mice was qualitatively similar in cholesterol ester, phosphatidylcholine, and phosphatidylethanolamine. The monoenoic fatty acids palmitoleic acid (16:1 n-7) and oleic acid (18:1 n-9) were increased markedly, whereas all n-6 and n-3 polyunsaturated fatty acids were nearly depleted in phospholipid and cholesterol ester species. The n-9 polyunsaturated fatty acid surrogate, Mead acid (20:3 n-9), substituted for arachidonic acid (20:4 n-6) and docosahexaenoic acid (22:6 n-3) in phospholipid, but not in cholesterol ester, species. Another notable difference was that adrenic acid (22:4 n-6) and docosapentaenoic acid (22:5 n-6), both metabolites of arachidonic acid, accumulated in phospholipid and cholesterol ester species of peritoneal cells, but not in liver cells, of essential fatty acid sufficient mice. The overall body of data presented illustrates the implementation of electrospray/tandem mass spectrometry as a method for facile and direct quantification of changes in lipid species during lipid metabolic studies.

Molecular chlorine generated by the myeloperoxidase-hydrogen peroxide-chloride system of phagocytes converts low density lipoprotein cholesterol into a family of chlorinated sterols

Oxidation of low density lipoprotein (LDL) may be of critical importance in triggering the pathological events of atherosclerosis. Myeloperoxidase, a heme protein secreted by phagocytes, is a potent catalyst for LDL oxidation in vitro, and active enzyme is present in human atherosclerotic lesions. We have explored the possibility that reactive intermediates generated by myeloperoxidase target LDL cholesterol for oxidation. LDL exposed to the myeloperoxidase-H2O2-Cl- system at acidic pH yielded a family of chlorinated sterols. The products were identified by mass spectrometry as a novel dichlorinated sterol, cholesterol alpha-chlorohydrin (6beta-chlorocholestane-(3beta,5alpha)-diol), cholesterol beta-chlorohydrin (5alpha-chlorocholestane-(3beta, 6beta)-diol), and a structurally related cholesterol chlorohydrin. Oxidation of LDL cholesterol by myeloperoxidase required H2O2 and Cl-, suggesting that hypochlorous acid (HOCl) was an intermediate in the reaction. However, HOCl failed to generate chlorinated sterols under chloride-free conditions. Since HOCl is in equilibrium with molecular chlorine (Cl2) through a reaction which requires Cl- and H+, this raised the possibility that Cl2 was the actual chlorinating intermediate. Consonant with this hypothesis, HOCl oxidized LDL cholesterol in the presence of Cl- and at acidic pH. Moreover, in the absence of Cl- and at neutral pH, Cl2 generated the same family of chlorinated sterols as the myeloperoxidase-H2O2-Cl- system. Finally, direct addition of Cl2 to the double bond of cholesterol accounts for dichlorinated sterol formation by myeloperoxidase. Collectively, these results indicate that Cl2 derived from HOCl is the chlorinating intermediate in the oxidation of cholesterol by myeloperoxidase. Our observations suggest that Cl2 generation in acidic compartments may constitute one pathway for oxidation of LDL cholesterol in the artery wall.

The substrate specificity of Saccharomyces cerevisiae myristoyl-CoA: protein N-myristoyltransferase. Polar probes of the enzyme's myristoyl-CoA recognition site

Saccharomyces cerevisiae myristoyl-CoA:protein N-myristoyltransferase (Nmt1p) is a monomeric enzyme that is essential for vegetative growth. Nmt1p catalyzes the co-translational transfer of myristate from CoA to the amino-terminal Gly of cellular proteins in an ordered Bi Bi reaction mechanism that initially involves binding of myristoyl-CoA to the apoenzyme. Forty one fatty acid analogs were synthesized to define features in the acyl chain of myristoyl-CoA which are important determinants of its recognition by Nmt1p's acyl-CoA binding site as well as to help us deduce the structure of the binding site itself. These analogs included dicarboxylic acids, omega-nitrocarboxylic acids, analogs equivalent in length to C13:0-C15:0 which contain electronegative halogens at their omega-termini, hydroxytetradecanoic acids with hydrogen replaced by OH from C3 to C13, and azidophenyl-containing fatty acids with the linear azide unit attached either meta or para to phenyl and with variations in the length of their methylene chains. These compounds were converted to their CoA derivatives using Pseudomonas acyl-CoA synthetase and then surveyed as substrates for purified Nmt1p in an in vitro assay system that included an octapeptide derived from residues 1-8 of the human immunodeficiency virus Pr55gag polyprotein precursor. The results suggest that the myristoyl-CoA binding site contains a conical-shaped "receptor" that interacts with the omega-terminus of the bound acyl chain of acyl-CoAs. The acuteness of this cone determines the enzyme's capacity to accommodate steric bulk at the omega-terminus as well as Nmt1p's sensitivity to the distance between the eclipsed C5-C6 bond of a bound acyl chain and its omega-terminus. The activity profile of the various analog-CoAs also indicates that the enzyme's myristoyl-CoA binding site can accommodate fatty acid analogs with marked increases in polarity at their omega-terminus (compared to C14:0) as long as their chain length is equivalent to that of myristate.

Mechanism-based inactivation of leukotriene A4 hydrolase/aminopeptidase by leukotriene A4. Mass spectrometric and kinetic characterization

"Suicide" inactivation of leukotriene (LT) A4 hydrolase/aminopeptidase occurs via an irreversible mechanism-based process which is saturable, of pseudo firstorder, and dependent upon catalysis. Data obtained with either recombinant enzyme or enzyme purified from human leukocytes were similar. Apparent binding constants and inactivation rate constants are equivalent, compatible with a single type of substrate-enzyme complex which partitions between two fates, turnover and inactivation. Both catalytic functions are inactivated, consistent with an overlapping active site for this bifunctional enzyme. The partition ratio (turnover/inactivation) for the LTA4-enzyme complex is 129 +/- 16 for LTA4 hydrolase activity and 124 +/- 10 for aminopeptidase activity. The pH dependence for turnover and inactivation are indistinguishable with a maximum at pH 8. L-Proline p-nitroanilide, a weak substrate with a high Km for the aminopeptidase affords only partial protection against inactivation by LTA4. However, two potent competitive inhibitors, bestatin and captopril, protect both catalytic processes from inactivation, consistent with an active-site specificity for the suicide event. Electrospray ionization mass spectrometry indicates that the molecular weight of pure recombinant enzyme is 69,399 +/- 4 and that covalent modification accompanies catalysis, producing an LTA4:enzyme adduct with a molecular weight 69,717 +/- 4 and a 1:1 stoichiometry. In agreement with kinetic data, electrospray ionization mass spectrometry shows that bestatin inhibits the covalent modification of enzyme by LTA4 and that the extent of modification is proportional to the loss of enzymatic activity.