From pelvic radiation to social isolation: a qualitative study of survivors' experiences of chronic bowel symptoms after pelvic radiotherapy

PURPOSE

We explored survivors' experiences of chronic bowel symptoms following pelvic radiotherapy, strategies employed in living with these symptoms, effects on daily activities, and roles at home and in the workplace.

METHODS

Semi-structured interviews were conducted with 28 individuals (10 gynaecological, 14 prostate, four anal/rectal cancer survivors) who had completed pelvic radiotherapy at least six months prior to data collection and who had experience of bowel symptoms during this post-treatment period. Reflexive thematic analysis was undertaken.

RESULTS

We propose four themes describing a process leading from experience of symptoms to withdrawal from activities and roles. These are (1) losing control (the experience of unintended anal leakage or discharge); (2) experiencing embarrassment and fear (the experience of embarrassment or fear of embarrassment as a result of discharge becoming public); (3) managing and reacting (acting to reduce the likelihood of discharge or to prevent this becoming public); and (4) restriction and withdrawal (avoiding specific activities or situations so as to reduce or remove the risk of embarrassment). Returning to the workplace presented additional challenges across these themes.

CONCLUSIONS

Impacts of chronic bowel symptoms can be severe. Survivors employ a variety of methods and strategies in living with their symptoms. Some of these support continued role fulfilment but some constitute a withdrawal from pre-treatment roles. Current healthcare provision and statutory protections fail to fully meet needs following pelvic radiotherapy.

IMPLICATIONS FOR CANCER SURVIVORS

There is a need to develop and implement evidence-based services and supported self-management programmes for survivors experiencing chronic bowel problems post-radiotherapy.

A Systematic Review of Population-Based Studies of Chronic Bowel Symptoms in Cancer Survivors following Pelvic Radiotherapy

Pelvic radiotherapy can damage surrounding tissue and organs, causing chronic conditions including bowel symptoms. We systematically identified quantitative, population-based studies of patient-reported bowel symptoms following pelvic radiotherapy to synthesize evidence of symptom type, prevalence, and severity. Medline, CINAHL, EMBASE, and PsychINFO were searched from inception to September 2022. Following independent screening of titles, abstracts, and full-texts, population and study characteristics and symptom findings were extracted, and narrative synthesis was conducted. In total, 45 papers (prostate, n = 39; gynecological, n = 6) reporting 19 datasets were included. Studies were methodologically heterogeneous. Most frequently assessed was bowel function ('score', 26 papers, 'bother', 19 papers). Also assessed was urgency, diarrhea, bleeding, incontinence, abdominal pain, painful hemorrhoids, rectal wetness, constipation, mucous discharge, frequency, and gas. Prevalence ranged from 1% (bleeding) to 59% (anal bleeding for >12 months at any time since start of treatment). In total, 10 papers compared radiotherapy with non-cancer comparators and 24 with non-radiotherapy cancer patient groups. Symptom prevalence/severity was greater/worse in radiotherapy groups and symptoms more common/worse post-radiotherapy than pre-diagnosis/treatment. Symptom prevalence varied between studies and symptoms. This review confirms that many people experience chronic bowel symptoms following pelvic radiotherapy. Greater methodological consistency, and investigation of less-well-studied survivor populations, could better inform the provision of services and support.

Understanding and addressing vaccine hesitancy in the context of COVID-19: development of a digital intervention

OBJECTIVES

Severe Acute Respiratory Coronavirus 2 (SARS-CoV-2) was identified in late 2019, spreading to over 200 countries and resulting in almost two million deaths worldwide. The emergence of safe and effective vaccines provides a route out of the pandemic, with vaccination uptake of 75-90% needed to achieve population protection. Vaccine hesitancy is problematic for vaccine rollout; global reports suggest only 73% of the population may agree to being vaccinated. As a result, there is an urgent need to develop equitable and accessible interventions to address vaccine hesitancy at the population level.

STUDY DESIGN

& Method: We report the development of a scalable digital intervention seeking to address COVID-19 vaccine hesitancy and enhance uptake of COVID-19 vaccines in the United Kingdom. Guided by motivational interviewing (MI) principles, the intervention includes a series of therapeutic dialogues addressing 10 key concerns of vaccine-hesitant individuals. Development of the intervention occurred linearly across four stages. During stage 1, we identified common reasons for COVID-19 vaccine hesitancy through analysis of existing survey data, a rapid systematic literature review, and public engagement workshops. Stage 2 comprised qualitative interviews with medical, immunological, and public health experts. Rapid content and thematic analysis of the data provided evidence-based responses to common vaccine concerns. Stage 3 involved the development of therapeutic dialogues through workshops with psychological and digital behaviour change experts. Dialogues were developed to address concerns using MI principles, including embracing resistance and supporting self-efficacy. Finally, stage 4 involved digitisation of the dialogues and pilot testing with members of the public.

DISCUSSION

The digital intervention provides an evidence-based approach to addressing vaccine hesitancy through MI principles. The dialogues are user-selected, allowing exploration of relevant issues associated with hesitancy in a non-judgmental context. The text-based content and digital format allow for rapid modification to changing information and scalability for wider dissemination.

A Prospective Study of Diffusion-weighted Magnetic Resonance Imaging as an Early Prognostic Biomarker in Chemoradiotherapy in Squamous Cell Carcinomas of the Anus

AIMS

The use of diffusion-weighted magnetic resonance imaging (DW-MRI) as a prognostic marker of treatment response would enable early individualisation of treatment. We aimed to quantify the changes in mean apparent diffusion coefficient (ΔADC_mean) between a DW-MRI at diagnosis and on fraction 8-10 of chemoradiotherapy (CRT) as a biomarker for cellularity, and correlate these with anal squamous cell carcinoma recurrence.

MATERIALS AND METHODS

This prospective study recruited patients with localised anal cancer between October 2014 and November 2017. DW-MRI was carried out at diagnosis and after fraction 8-10 of radical CRT. A region of interest was delineated for all primary tumours and any lymph nodes >2 cm on high-resolution T₂-weighted images and propagated to the ADC map. Routine clinical follow-up was collected from Nation Health Service electronic systems.

RESULTS

Twenty-three of 29 recruited patients underwent paired DW-MRI scans. Twenty-six regions of interest were delineated among the 23 evaluable patients. The median (range) tumour volume was 13.6 cm³ (2.8-84.9 cm³). Ten of 23 patients had lesions with ΔADC_mean ≤ 20%. With a median follow-up of 41.2 months, four patients either failed to have a complete response to CRT or subsequently relapsed. Three of four patients with disease relapse had lesions demonstrating ΔADC_mean <20%, the other patient with persistent disease had ΔADC_mean of 20.3%.

CONCLUSIONS

We demonstrated a potential correlation between patients with ΔADC_mean <20% and disease relapse. Further investigation of the prognostic merit of DW-MRI change is needed in larger, prospective cohorts.

Oxygen-enhanced MRI MOLLI T1 mapping during chemoradiotherapy in anal squamous cell carcinoma

BACKGROUND AND PURPOSE

Oxygen-enhanced magnetic resonance imaging (MRI) and T1-mapping was used to explore its effectiveness as a prognostic imaging biomarker for chemoradiotherapy outcome in anal squamous cell carcinoma.

MATERIALS AND METHODS

T2-weighted, T1 mapping, and oxygen-enhanced T1 maps were acquired before and after 8-10 fractions of chemoradiotherapy and examined whether the oxygen-enhanced MRI response relates to clinical outcome. Patient response to treatment was assessed 3 months following completion of chemoradiotherapy. A mean T1 was extracted from manually segmented tumour regions of interest and a paired two-tailed t-test was used to compare changes across the patient population. Regions of subcutaneous fat and muscle tissue were examined as control ROIs.

RESULTS

There was a significant increase in T1 of the tumour ROIs across patients following the 8-10 fractions of chemoradiotherapy (paired t-test, p < 0.001, n = 7). At baseline, prior to receiving chemoradiotherapy, there were no significant changes in T1 across patients from breathing oxygen (n = 9). In the post-chemoRT scans (8-10 fractions), there was a significant decrease in T1 of the tumour ROIs across patients when breathing 100% oxygen (paired t-test, p < 0.001, n = 8). Out of the 12 patients from which we successfully acquired a visit 1 T1-map, only 1 patient did not respond to treatment, therefore, we cannot correlate these results with clinical outcome.

CONCLUSIONS

These clinical data demonstrate feasibility and potential for T1-mapping and oxygen enhanced T1-mapping to indicate perfusion or treatment response in tumours of this nature. These data show promise for future work with a larger cohort containing more non-responders, which would allow us to relate these measurements to clinical outcome.

Characteristics of people with pressure ulcers using one year's routinely collected data in a defined diverse community

OBJECTIVE

To determine if meaningful patient characteristics pertaining to pressure ulcers (PU) can be derived from routinely collected community health data.

METHODS

A retrospective cohort analysis of records was carried out. To provide a detailed dataset on PU for the community of interest, demographic, general medical and PU data were extracted from mandatory incident reports and audit of electronic and paper medical records. This study is reported in accordance with the RECORD Guidelines from the Equator Network. Adult patients were enrolled from a district nursing service in the target region (n=1085) during 2015. The target region was based on a geographical region bounded by a single postcode district (target region) consisting of 62,000 people of whom approximately 50,000 were adults, 3000 of whom were aged >75 years.

RESULTS

The total number of recorded PUs was n=137 in 103 individuals. Data from mandatory incident reports was obtainable for nearly all variables. Electronic and paper medical records were less reliable due to missing data.

CONCLUSION

Detailed characteristics of community-dwelling PU patients can be derived from routinely collected data, and provides various forms and levels of information which could feed into different projects. The use of mandatory reporting fields increases the level of reporting and reduces missing data. Data enriched with information from electronic and paper records could inform the addition of variables to mandatory forms to improve characterisation of community dwellers with PUs.

Abstract P1-08-06: Not presented

This abstract was not presented at the symposium.

Abstract A015: Protein arginine deiminase enzymes which citrullinate epitopes for MHC II presentation are independent predictors of survival in colorectal cancer

Citrullination of proteins is associated with a number of autoimmune diseases. Protein Arginine Deiminases (PADs) are a family of Ca2+ dependent enzymes that under cellular stress post-translationally convert arginine to citrulline within protein substrates to generate self-modified neo-antigens. It has been shown that presentation of citrullinated peptides on MHC class II stimulates CD4 T cells to mediate potent anti-tumor immunity (1). In this study we focus on the role of the PADI2 and PADI4 family members in colorectal cancer. Using a tissue microarray of colorectal cancers and compiling a comprehensive database of clinicopathological variables, the expression of PADI2 and PADI4 was assessed by immunohistochemistry in a study cohort. This data was used to correlate PADI2 and PADI4 expression with patient survival.

In the study cohort 462 colorectal tumors were stained for PADI2 and PADI4. Of these 171 (37%) and 231 (50%) could not be evaluated for PADI2 and PADI4 staining respectively due to the absence of enough tissue core or no evaluable tumor cells (i.e. all stroma) in the core. Of the 291 evaluable colorectal tumors stained with a PADI2 specific antibody, only 18/291 (6.2%) tumors failed to stain. A further 153/291 (52.5%) stained weakly, 102/291 (35.1%) moderate and 18/291 (6.2%) stained strongly. Of the 231 evaluable colorectal tumors stained with a PADI4 specific antibody, no tumors failed to stain. All cases stained strongly for PADI4 expression within the nucleus. In the cytoplasm 63/231 (27.3%) stained weakly, 143/231 (61.9%) moderate and 25/231 (10.8%) stained strongly.

PADI2 expression did not correlate with any clinicopathological variables whereas nuclear but not cytoplasmic PADI4 showed a strong association with histological type (p = 0.008). Kaplan-Meier analysis showed there was a correlation of PADI2 and cytoplasmic PADI4 expression with improved survival. Expression of PADI2 gave an increase in survival time from 44.8 months (95% CI 24.3 to 65.4) to 76.2 months (95% CI 69.9 to 82.4, log rank test, p = 0.012). Expression of cytoplasmic PADI4 increased survival time from 57.9 months (95% CI 43.6 to 72.3) to 77.3 months (95% CI 69.6 to 85.1, log rank test, p = 0.012). No significant correlation was observed between PADI2 and the cytoskeletal protein Vimentin or the glycolytic enzyme α-enolase both reported to be citrullinated by PAD enzymes. PADI2 expression was significantly associated with expression of the Nuclear antigen Ki67 (p = 0.046) a cellular marker for proliferation. Nuclear PADI4 significantly correlated with the cytoplasmic glycolytic enzyme α-enolase only (p = 0.001) and cytoplasmic PADI4 was highly significantly associated with α-enolase located in both the cytoplasm (p&lt;0.001) and shorter nuclear form (p&lt;0.001) known as MBP-1, a transcription factor known to downregulate the activity of the c-myc proto-oncogene. Cytoplasmic PADI4 expression also significantly correlated with expression of the anti-apoptotic protein Bcl2 (p = 0.028). Multivariate analysis using Cox regression showed that PADI2 (p = 0.040)/Cytoplasmic PADI4 (p = 0.036), the stress related protein MICA (p = 0.006/0.022), vascular invasion (p&lt;0.001, 0.040) and tumor stage (p&lt;0.001/&lt;0.001) are all independent markers of good prognosis in colorectal cancer. These results are consistent with the hypothesis that stressed tumor cells present citrullinated epitopes allowing their growth to be controlled by T cells.

References

1. Brentville VA, Metheringham RL, Gunn B, Symonds P, Daniels I, Gijon M, Cook K, Xue W, Durrant LG (2016). Citrullinated vimentin presented on MHC-II in tumor cells is a target for CD4+ T cell-mediated antitumor immunity. Cancer Research 2016 Feb 1;76(3):548-60

Citation Format: R. Metheringham, M. Gijon, I. Daniels, K. Cook, P. Symonds, T. Pitt, W. Xue, V. Brentville, L. Durrant. Protein arginine deiminase enzymes which citrullinate epitopes for MHC II presentation are independent predictors of survival in colorectal cancer [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A015.

Quantifying target-specific motion in anal cancer patients treated with intensity modulated radiotherapy (IMRT)

Background and purpose

Intensity modulated radiotherapy requires all target areas to be treated by a single radiotherapy plan. In anal cancer, the pelvic nodes, inguinal nodes and primary tumour represent three different targets. We aim to calculate target-specific motion in anal cancer radiotherapy, when delivered using a single pelvic online auto-match.

Materials and methods

Twenty consecutive patients treated using IMRT at a single institution were studied. CBCTs were retrospectively re-matched around the inguinal nodes and primary tumour. Match values were recorded relative to origin, defined as pelvic CBCT auto-match. Systematic and random errors were quantified to determine target-specific motion and suggested margins calculated using van Herk formulae.

Results

The suggested margins to cover the independent motion of the inguinal and anal targets for LR, CC and AP set up around the inguinal nodes were 1.5 mm, 2.7 mm and 2.8 mm; and the primary tumour were, 4.6 mm, 8.9 mm and 5.2 mm respectively.

Conclusions

Target-specific set up will likely result in reduced treatment volumes and as such reduced toxicity. This is the first time a relationship has been described between pelvic bones, inguinal nodes and primary tumour. The PLATO study will prospectively assess the toxicity and outcomes of this target-specific margins strategy.

ARCII: A phase II trial of the HIV protease inhibitor Nelfinavir in combination with chemoradiation for locally advanced inoperable pancreatic cancer

BACKGROUND AND PURPOSE

Nelfinavir can enhance intrinsic radiosensitivity, reduce hypoxia and improve vascularity. We conducted a phase II trial combining nelfinavir with chemoradiotherapy (CRT) for locally advanced inoperable pancreatic cancer (LAPC).

MATERIALS AND METHODS

Radiotherapy (50.4Gy/28 fractions; boost to 59.4Gy/33 fractions) was administered with weekly gemcitabine and cisplatin. Nelfinavir started 3-10days before and was continued during CRT. The primary end-point was 1-year overall survival (OS). Secondary end-points included histological downstaging, radiological response, 1-year progression free survival (PFS), overall survival (OS) and treatment toxicity. An imaging sub-study (n=6) evaluated hypoxia ((18)F-Fluoromisonidazole-PET) and perfusion (perfusion CT) during induction nelfinavir.

RESULTS

The study closed after recruiting 23 patients, due to non-availability of Nelfinavir in Europe. The 1-year OS was 73.4% (90% CI: 54.5-85.5%) and median OS was 17.4months (90% CI: 12.8-18.8). The 1-year PFS was 21.8% (90% CI: 8.9-38.3%) and median PFS was 5.5months (90% CI: 4.1-8.3). All patients experienced Grade 3/4 toxicity, but many were asymptomatic laboratory abnormalities. Four of 6 patients on the imaging sub-study demonstrated reduced hypoxia and increased perfusion post-nelfinavir.

CONCLUSIONS

CRT combined with nelfinavir showed acceptable toxicity and promising survival in pancreatic cancer.

Modeling early haematologic adverse events in conformal and intensity-modulated pelvic radiotherapy in anal cancer

Background and purpose

To determine if there are differences between dose to pelvic bone marrow (PBM) using intensity modulated radiotherapy (IMRT) under UK guidance versus conformal radiotherapy (CRT) per ACT II protocol and if differences translate to rates of early haematological adverse events grade 3 or greater (HT3+).

Methods and materials

Two groups of 20+ patients, treated under IMRT and CRT regimes respectively, were identified. All patients underwent weekly blood cell count: haemoglobin (HgB), white cell count (WCC), absolute neutrophil count (ANC) and platelets (plats).

Percent volume of PBM and sub structures receiving 5–25 Gy were tested for statistical significance. Regression models were used to test for correlation to blood counts. NTCP modeling was also performed.

Results

PMB dose metrics showed a significant increase in the IMRT group. Regression analysis showed iliac and lumbosacral PBM dose metrics to associate with reduced nadir ANC and WCC. NTCP at HT3+ was 0.13 using IMRT relative to 0.07 using CRT (p < 0.05).

Conclusion

Whilst this is a relatively small retrospective study and lacks information on the distribution of active PBM, IMRT treatment has been shown to significantly increase PMB irradiation. PBM dose metrics have been shown to be predictive of WCC and ANC suppression. NTCP modeling predicts much high risk of HT3+. Paradoxically, actual rates of HT3+ were comparable suggesting that differences in the distributions of dose metrics maybe a significant factor and/or that there are insufficiency in the NTCP modeling.

Identification of vitamin B1 metabolism as a tumor-specific radiosensitizing pathway using a high-throughput colony formation screen

Colony formation is the gold standard assay for determining reproductive cell death after radiation treatment, since effects on proliferation often do not reflect survival. We have developed a high-throughput radiosensitivity screening method based on clonogenicity and screened a siRNA library against kinases. Thiamine pyrophosphokinase-1 (TPK1), a key component of Vitamin B1/thiamine metabolism, was identified as a target for radiosensitization. TPK1 knockdown caused significant radiosensitization in cancer but not normal tissue cell lines. Other means of blocking this pathway, knockdown of thiamine transporter-1 (THTR1) or treatment with the thiamine analogue pyrithiamine hydrobromide (PyrH) caused significant tumor specific radiosensitization. There was persistent DNA damage in cells irradiated after TPK1 and THTR1 knockdown or PyrH treatment. Thus this screen allowed the identification of thiamine metabolism as a novel radiosensitization target that affects DNA repair. Short-term modulation of thiamine metabolism could be a clinically exploitable strategy to achieve tumor specific radiosensitization.

Volumetric analysis of anal cancer relapses following radical chemoradiation

576

Background: Definitive chemoradiotherapy is standard of care in anal squamous cell carcinoma. The ACT II trial set the standard achieving three year overall survival rates of 73%. However patients with locally advanced disease have a ~50% local relapse rate. Studies have failed to demonstrate an improvement in local relapse rate by altering the systemic therapy. Although 2/3 of relapses are local as opposed to regional or distant, there is limited knowledge on the 3D position of these relapses. We aim to retrospectively review the patterns of local failure in three dimensions, relative to the radiotherapy plan. Methods: Between February 2007 and April 2012, 77 patients were treated for squamous cell carcinoma of the anus with radical chemoradiotherapy. Early stage (T0/2) and locally advanced (T3/4) tumours constituted 53% and 44% respectively. 37% of patients had nodal disease. As per ACT II protocol we used a gross tumour volume (GTV) to PTV margin of 3cm and prescribed to a dose of 50.4Gy. In patients with a local recurrence, imaging from the time of recurrence was imported into the radiotherapy planning system. The volume and site of gross recurrence was noted relative to the previous GTV and 95% isodose line. The mean dose delivered to the relapsed area was calculated. Results: Median follow-up was 42 months (range 14 to 78 months). Eight (10%) patients failed to respond. Six (8%) patients developed an isolated local relapse, 2 (3%) distant metastatic disease alone and 1 both local and distant relapse. Of those that relapsed locally, 5 patients were T2N0, one T3N0 and 1 node positive. There were no regional relapses. The entire macroscopic relapse lay within the 95% isodose line of the 50.4Gy in all patients. The median percentage of relapse that lay within GTV was 63% (range 29 to 100%). A GTV to PTV margin of 2cm would have encompassed all macroscopic relapses. The median doses to relapsed area was 52Gy (range 51Gy to 53Gy) with the minimum dose to any relapsed area being 49Gy. Conclusions: The majority of relapses centred on the GTV suggesting the gross tumour was uncontrolled with current doses in these patients. A reduction of GTV to PTV margin may be appropriate, facilitating trials of dose escalation with the aim of improving outcomes.

High levels of cleaved caspase-3 in colorectal tumour stroma predict good survival

Aim:

The primary aim was to determine the prognostic significance of apoptosis in colorectal tumour cells and tumour-associated stroma. A secondary aim was to determine whether apoptosis was related to immune surveillance.

Methods:

Immunohistochemistry was performed using monoclonal antibodies recognising cleaved caspase-3 (CC3), cleaved poly (ADP-ribose) polymerase (PARP), p53, Bcl2, MHC-II, B cells (CD16), macrophages (CD68) and T cells (CD3), on a tissue microarray of 462 colorectal tumours.

Results:

Kaplan–Meier analysis demonstrated that patients with high expression of CC3 in the tumour or CC3 or cleaved PARP in tumour-associated stroma have a good prognosis. This suggests that tumour stroma is promoting tumourigenesis and that high levels of death within the stroma breaks this link. CC3 levels in the tumour correlated with cleaved PARP and MHC-II expression but not with CD16, CD68, CD3, p53 or Bcl2 expression. CC3 levels on tumour-associated stroma also correlated with cleaved PARP and MHC-II expression but not with CD16, CD68, CD3, p53 or Bcl2 expression. Tumour cells express MHC-II in response to IFN-γ, suggesting that this may be one of the initiators of apoptosis within the good prognosis tumours. Although 73% of the MHC-II-positive tumour had high levels of apoptosis, many tumours had high levels of apoptosis in the absence of MHC-II, implying that this is only one of many causes of apoptosis within tumours. On multivariate analysis, using Cox's proportional hazards model, tumour stage, vascular invasion and expression of CC3 in tumour-associated stroma were shown to be independent markers of prognosis.

Conclusion:

This study shows that a high level of apoptosis within colorectal tumour-associated stroma is an independent marker of good prognosis.

Structure, ratios and patterns of release in the sex pheromone of an aphid, Dysaphis plantaginea

Insect communication is primarily via chemicals. In Aphidinae aphids, the structure and ratio of iridoid (monoterpenoid) chemicals are known to be important components of the sex pheromone. However, for enhanced species specificity, it has been suggested that release of sex pheromone might be restricted to a narrow time period within the diel cycle. Here, we determine the structure, ratios and release patterns of iridoid chemicals produced by a serious global pest, the rosy apple aphid, Dysaphis plantaginea. Volatiles were collected from batches of oviparae (sexual females) and chemicals identified by gas chromatography, mass-spectrometry and microscale NMR spectroscopy.(1R,4aS,7S,7aR)-Nepetalactol and(4aS,7S,7aR)-nepetalactone were detected in a 3.7:1 ratio. To investigate timing of release, we constructed a sequential sampling device that allowed volatile chemicals to be captured hourly from 95 same-aged oviparae over 20 consecutive days. Release patterns of the two sex pheromone components show that D. plantaginea oviparae release high levels of the two components during photophase and low levels during scotophase. Release of the two components increased significantly during the first 3 h of photophase and thereafter remained at a high level until the onset of scotophase. The ratio of(1R,4aS,7S,7aR)-nepetalactol to(4aS,7S,7aR)-nepetalactone released did not change significantly between days two to 14 of the adult stadium, but from the 15th day onward there was a significant decrease in the relative amount of(1R,4aS,7S,7aR)-nepetalactol. Pheromone release was greatest on the eighth day of the adult stadium, with up to 8.4 ng of pheromone released per ovipara per hour. This is the first report on the full structural identification and ratios of volatile iridoid components collected from D. plantaginea oviparae and is also the most detailed temporal study on sex pheromone release from any aphid species. The lack of a temporally narrow and distinct period of very high sex pheromone release suggests that alternative mechanisms or factors for species recognition and isolation may be important. Findings are discussed broadly in relation to the biology of the aphid.

Generation of anti-idiotype immune responses following vaccination with idiotype-protein pulsed dendritic cells in myeloma

Myeloma cells produce immunoglobulin which is unique to the malignant clone and presents antigenic determinants, or idiotypes, which may function as a tumour-specific antigen. The availability of significant quantities of idiotype protein in the serum makes immunotherapeutic strategies utilizing this protein to generate an anti-idiotype immune response an attractive prospect. We treated two patients with advanced refractory myeloma with a series of four vaccinations using autologous idiotype-protein pulsed dendritic cells combined with adjuvant GM-CSF. The vaccinations were well tolerated with a mild fever post-vaccination in one patient. An idiotype-specific T-cell proliferative response developed in both patients. This T-cell response was associated with the production of gamma-interferon, indicating a TH-1-like response. Furthermore, one patient developed anti-idiotype IgM antibodies. However, no idiotype-specific cytotoxic T-cell response could be demonstrated. Further investigation is warranted to define the optimal conditions for dendritic cell culture and priming to maximize the anti-tumour immune response.

A magnetic colloid system for isolation of rare cells from blood for fish analysis

To improve cell recovery of trophoblast and nucleated red blood cells from maternal blood for diagnosis of chromosomal abnormalities, we have investigated the use of a magnetic sorting system that utilizes a ferrofluid. The main advantage of this system is that the beads used are small enough to allow visualization of chromosome-specific sequences by fluorescence in situ hybridization (FISH). The ferrofluid was validated using MAb340, a trophoblast-specific antibody, and anti-CD71, used to sort for nucleated red blood cells. Antigen-positive cells could be efficiently sorted from a 1000-fold excess of antigen-negative cells and easily stained by FISH. We are currently evaluating its use on maternal blood samples.

Non-invasive prenatal diagnosis by isolation of both trophoblasts and fetal nucleated red blood cells from the peripheral blood of pregnant women

OBJECTIVE

To isolate fetal trophoblasts and nucleated red blood cells from the peripheral blood of pregnant women.

DESIGN

Trophoblasts were isolated from whole blood of women in the first trimester of pregnancy by a specific monoclonal antibody, 340. Nucleated red blood cells were isolated by separating whole blood on a triple gradient, staining with ferromagnetic particles coated with an antitransferrin monoclonal antibody and separated on a mini magnetic activated cell sorting (MACS) column. Sorted cells were sexed using a nested polymerase chain reaction for a specific sequence on the Y chromosome and the sex was confirmed by karyotyping of chorionic villus samples.

PARTICIPANTS

Patients between 10 and 14 weeks of pregnancy who were undergoing elective chorionic villus sampling for the detection of fetal aneuploidies.

MAIN OUTCOME MEASURE

Fetal sex determined by polymerase chain reaction on fetal cells sorted from maternal blood.

RESULTS

When both trophoblasts and nucleated red blood cells were sorted, fetal sex was correctly predicted in 12/13 cases (92%), which included correct diagnosis of five of six male pregnancies. More importantly the two techniques were complementary, with only one male pregnancy being diagnosed on both trophoblasts and nucleated red blood cells, two being detected only with trophoblasts and two on nucleated red blood cells alone. No false positives (male signal from a female pregnancy) were diagnosed with either trophoblasts or nucleated red blood cells even with the highly sensitive nested polymerase chain reaction technique, which is very prone to contamination. This study also shows that it is possible to isolate both trophoblasts and nucleated red blood cells from the same sample of maternal blood.

CONCLUSION

Fetal cells can be isolated from maternal blood at around 10 weeks of pregnancy.

Immune recognition of human colonic-tumour-associated MUC-2 mucins using an anti-peptide antibody

In human intestinal malignancy, alterations occur in the expression of mucins defined by the MUC-2 gene. These changes include the unmasking of epitopes in the mucin protein core. In order to probe these modifications associated with mucins of the malignant phenotype, a monoclonal antibody (MAb) was developed against synthetic peptide with a sequence based upon that of the protein core of the MUC-2 mucin. The antibody (designated 996) was shown to recognize a high-molecular-weight glycoprotein from colonic carcinoma tissue. The material reacted uniformly with Concanavalin A but variably with other lectins, indicating heterogeneity in the associated oligosaccharide side chains. The protein core was accessible both to 996 antibody binding and to degradation with proteases. Immunization with the affinity-purified mucin-like material elicited antibodies reactive with both the immunogen and the synthetic peptides, confirming the immunogenic character of protein-core determinants. Epitope mapping studies, using synthetic peptides in solution and synthetic peptides tethered to the heads of plastic pins, indicated that the minimum epitope for the 996 antibody is a tetramer of T G T Q. Antibody interaction with the glutamine (Q) residue was determined to be of major importance in the antigen-antibody reaction. The findings illustrate the characterization of an anti-peptide antibody which may be used to probe alterations in MUC-2 mucin expression associated with human intestinal malignant disease.

Inhibitory effects of the gastrin receptor antagonist (L-365,260) on gastrointestinal tumor cells

A selective gastrin receptor (GR) antagonist, L-365,260 is bound to the GR on AR42J cells with a potency 7.5-fold less than G17 (50% inhibitory concentration [IC50] G17, 6 x 10(-9) mol/l; IC50 L365-260, 4.5 x 10(-8) mol/l). G17 is mitogenic for AR42J cells, as assessed by 75Se-selenomethionine uptake and L-365,260 at concentrations of 2.5 x 10(-6) mol/l and 2.5 x 10(-7) mol/l, (55X and 5.5 X the dose required to displace 50% 125I G17, respectively), and reduced optimal G17 stimulated mitogenesis in 75% of experiments. The basal growth of two human colon cancer cell lines, LoVo and C146 was reduced by L-365,260 (2.5 x 10(-7) mol/l) after 5 days of treatment to 44% and 64% of the control, respectively. However, inhibition was followed by a rebound of growth to control levels. The growth of AR42J xenografts in nude mice was increased by administration of G17 (10 micrograms/mouse/d, P less than 0.027). This increase was blocked by coadministration of oral L-365,260 (5 mg/kg/d, P less than 0.034). L-365,260 could be an important therapeutic agent in slowing the growth of GR-positive, G17-sensitive gastrointestinal tumors.

Gastrin: growth enhancing effects on human gastric and colonic tumour cells

Two colorectal (HT29, LoVo) and one gastric (MKN45) human tumour cell lines were examined for their in vitro trophic response to human gastrin-17. MKN45 and HT29 responded by increased 75Se selenomethionine uptake to exogenous gastrin (139 +/- 5.5% and 123 +/- 3% of control values respectively) whereas LoVo showed no significant response to this hormone. When these same cell lines were grown as xenografts in nude mice, similar responses were seen to exogenously administered human gastrin-17 (10 micrograms mouse-1 day-1, subcutaneous injection). MKN45 xenografts showed a greater response to continuously administered gastrin (osmotic mini-pumps, (10 micrograms mouse-1 day-1) when compared to the same dose given via a subcutaneous bolus injection. The hormone-treated xenografts had a two-fold increase in tumour cross-sectional area and growth rate when compared to saline-treated controls. Dose-response studies revealed that 0.4 micrograms gastrin mouse-1 day-1 appeared to be the minimally effective dose. As gastric and colorectal tumour cells show a trophic response to gastrin, antagonists of the gastrin receptor may prevent this effect causing tumour stasis. The gastric tumour cell line, MKN45, is gastrin-responsive and would be an ideal model for screening potent receptor antagonists.

Potentiation of anti-carcinoembryonic antigen immunotoxin cytotoxicity by monoclonal antibodies reacting with co-expressed carcinoembryonic antigen epitopes

The initial step in ricin A-chain (RTA)-immunotoxin-mediated cell cytotoxicity involves binding to the target cell Ag through the antibody moiety. One of the factors influencing this is the affinity of the antibody component for the target cell Ag. Multiple epitopes on carcinoembryonic Ag have been mapped providing a range of mAb of known specificity. These have been used to show that the cytotoxicity of an immunotoxin containing RTA conjugated to an anti-carcinoembryonic Ag mAb (228-RTA) is potentiated by mAb recognizing different epitopes. The potentiating antibodies also increased the level of target cell binding of antibody 228. Cross-linking of cell bound antibody was not involved because monovalent fragments of a potentiating antibody were effective. The potentiating antibodies modified the binding affinity of 228 antibody increasing the t1/2 of antibody at the tumor cell surface. This increased the dwell time of cell bound antibody and using conjugates of 228 linked to albumin-tetramethylrhodamine it was shown to enhance conjugate endocytosis. These investigations indicate that enhanced antibody affinity leads to increased endocytosis of bound immunoconjugate and potentiates cytotoxicity.

Potentiation of anti-carcinoembryonic antigen immunotoxin cytotoxicity by monoclonal antibodies reacting with co-expressed carcinoembryonic antigen epitopes

The initial step in ricin A-chain (RTA)-immunotoxin-mediated cell cytotoxicity involves binding to the target cell Ag through the antibody moiety. One of the factors influencing this is the affinity of the antibody component for the target cell Ag. Multiple epitopes on carcinoembryonic Ag have been mapped providing a range of mAb of known specificity. These have been used to show that the cytotoxicity of an immunotoxin containing RTA conjugated to an anti-carcinoembryonic Ag mAb (228-RTA) is potentiated by mAb recognizing different epitopes. The potentiating antibodies also increased the level of target cell binding of antibody 228. Cross-linking of cell bound antibody was not involved because monovalent fragments of a potentiating antibody were effective. The potentiating antibodies modified the binding affinity of 228 antibody increasing the t1/2 of antibody at the tumor cell surface. This increased the dwell time of cell bound antibody and using conjugates of 228 linked to albumin-tetramethylrhodamine it was shown to enhance conjugate endocytosis. These investigations indicate that enhanced antibody affinity leads to increased endocytosis of bound immunoconjugate and potentiates cytotoxicity.

Diagnostic imaging of gynecologic tumors with the monoclonal antibody 791T/36

One hundred twenty-three patients with suspected primary or recurrent gynecologic cancer were imaged after infusion with radiolabeled antitumor monoclonal antibody (791T/36). Overall sensitivity of tumor detection was 87% and specificity was 75%. Indium 111- and iodine 131-labeled antibody were compared, the former yielding a higher specificity for tumor detection. This antibody shows potential for routine tumor detection, particularly in cases of suspected recurrent cancer, but the development of antimouse antibodies is a drawback to this technique still to be overcome. The specific targeting of cytotoxic agents with this antibody is in progress.

Expression of HLA class I alpha chain determinants by human X mouse hybrid T cells is correlated with HLA-beta 2m but not with H-2

The expression of HLA class I alpha chains by clones derived from a human X mouse T-cell line containing human chromosomes 6 and 15 was analysed by immunofluorescence. Evidence is presented showing that the expression of HLA class I alpha chains is associated with HLA-beta 2m. This is based on the phenotypic and quantitative fluorescence flow cytometric analysis of a series of cloned hybrids. In contrast, HLA and H-2 class I determinants show no evidence of such correlation. Results of cell-sorting indicate that the loss of HLA class I alpha chain expression is due to phenotypic modulation, in addition to gene segregation.

Relative sensitivity of V79 and V79/79 cells to spontaneous and induced mutation to 6-thioguanine and ouabain resistance

The relative responses of V79 and V79/79 cells to mutation to 6-thioguanine (6TGR) and ouabain resistance (OUAR) have been compared in unmutagenized cells and after exposure to ethyl methanesulphonate (EMS), N-methyl-N-nitrosourea (MNU) and ultraviolet light. In the V79/79 cell line, the spontaneous frequency of 6TGR colonies but not of OUAR colonies was enhanced compared to that in V79 cells. This appears to be the result of a reduced growth rate and plating efficiency of V79/79 cells and does not reflect a real difference in spontaneous mutability. V79/79 cells were more sensitive than V79 to the cytotoxic effects of all three mutagens, but induced mutation by UV, EMS and MNU to 6TGR was similar in the two cell lines. The lack of a differential response for induced mutation to 6TGR may reflect: (a) differences in selective stringency of thioguanine in the two cell lines, and (b) the greater susceptibility of V79/79 cells to induced chromosome damage. The relative mutability of the two cell lines to OUAR was dependent on the mutagen used. V79 cells were significantly more mutable than V79/79 cells after MNU exposure, but the two cell lines were similar in sensitivity to EMS-induced mutation. After UV-irradiation, however, V79/79 cells were morem utable than V79 cells. The differential response of the two cell lines to MNU suggests that O6-methylguanine is potentially mutagenic in V79 cells but is both potentially lethal and potentially mutagenic in the more sensitive V79/79 cells. The absence of a differential response to EMS-induced mutagenesis suggests that methylated and ethylated bases are repaired differently in Chinese hamster cells. The hypermutability of V79/79 cells by UV-irradiation indicates that thymine dimers are potentially lethal and potentially mutagenic in both cell lines.