Precision peptide theranostics: developing N- to C-terminus optimized theranostics targeting cholecystokinin-2 receptor

Peptides are ideal for theranostic development as they afford rapid target accumulation, fast clearance from background tissue, and exhibit good tissue penetration. Previously, we developed a novel series of peptides that presented discreet folding propensity leading to an optimal candidate [68Ga]Ga-DOTA-GA1 ([D-Glu]6-Ala-Tyr-NMeGly-Trp-NMeNle-Asp-Nal-NH2) with 50 pM binding affinity against cholecystokinin-2 receptors (CCK2R). However, we were confronted with challenges of unfavorably high renal uptake. Methods: A structure activity relationship study was undertaken of the lead theranostic candidate. Prudent structural modifications were made to the peptide scaffold to evaluate the contributions of specific N-terminal residues to the overall biological activity. Optimal candidates were then evaluated in nude mice bearing transfected A431-CCK2 tumors, and their biodistribution was quantitated ex vivo. Results: We identified and confirmed that D-Glu3 to D-Ala3 substitution produced 2 optimal candidates, [68Ga]Ga-DOTA-GA12 and [68Ga]Ga-DOTA-GA13. These radiopeptides presented with high target/background ratios, enhanced tumor retention, excellent metabolic stability in plasma and mice organ homogenates, and a 4-fold reduction in renal uptake, significantly outperforming their non-alanine counterparts. Conclusions: Our study identified novel radiopharmaceutical candidates that target the CCK2R. Their high tumor uptake and reduced renal accumulation warrant clinical translation.

An immunomodulating peptide with potential to suppress tumour growth and autoimmunity

Cancers and autoimmune diseases commonly co-exist and immune checkpoint inhibitor therapy (ICI) exacerbates autoimmune pathologies. We recently described a lipidic peptide, designated IK14004, that promotes expansion of immunosuppressive T regulatory (Treg) cells and uncouples interleukin-2 from interferon-gamma production while activating CD8+ T cells. Herein, we report IK14004-mediated inhibition of Lewis lung cancer (LLC) growth and re-invigoration of splenocyte-derived exhausted CD4+ T cells. In human immune cells from healthy donors, IK14004 modulates expression of the T cell receptor α/β subunits, induces Type I IFN expression, stimulates natural killer (NK) cells to express NKG2D/NKp44 receptors and enhances K562 cytotoxicity. In both T and NK cells, IK14004 alters the IL-12 receptor β1/β2 chain ratio to favour IL-12p70 binding. Taken together, this novel peptide offers an opportunity to gain further insight into the complexity of ICI immunotherapy so that autoimmune responses may be minimised without promoting tumour evasion from the immune system.

Early circulating tumor DNA dynamics at the commencement of curative-intent radiotherapy or chemoradiotherapy for NSCLC

Background

The kinetics of circulating tumor DNA (ctDNA) release following commencement of radiotherapy or chemoradiotherapy may reflect early tumour cell killing. We hypothesised that an increase in ctDNA may be observed after the first fraction of radiotherapy and that this could have clinical significance.

Materials and methods

ctDNA analysis was performed as part of a prospective, observational clinical biomarker study of non-small cell lung cancer (NSCLC) patients, treated with curative-intent radiotherapy or chemoradiotherapy. Blood was collected at predefined intervals before, during (including 24 h after fraction 1 of radiotherapy) and after radiotherapy/chemoradiotherapy. Mutation-specific droplet digital PCR assays used to track ctDNA levels during and after treatment.

Results

Sequential ctDNA results are available for 14 patients with known tumor-based mutations, including in EGFR, KRAS and TP53, with a median follow-up of 723 days (range 152 to 1110). Treatments delivered were fractionated radiotherapy/chemoradiotherapy, in 2-2.75 Gy fractions (n = 12), or stereotactic ablative body radiotherapy (SABR, n = 2). An increase in ctDNA was observed after fraction 1 in 3/12 patients treated with fractionated radiotherapy with a complete set of results, including in 2 cases where ctDNA was initially undetectable. Neither SABR patient had detectable ctDNA immediately before or after radiotherapy, but one of these later relapsed systemically with a high detected ctDNA concentration.

Conclusions

A rapid increase in ctDNA levels was observed after one fraction of fractionated radiotherapy in three cases. Further molecular characterization will be required to understand if a "spike" in ctDNA levels could represent rapid initial tumor cell destruction and could have clinical value as a surrogate for early treatment response and/or as a means of enriching ctDNA for mutational profiling.

A genome-wide CRISPR/Cas9 screen identifies DNA-PK as a sensitiser to 177Lutetium-DOTA-octreotate radionuclide therapy

Peptide receptor radionuclide therapy (PRRT) using 177Lutetium-DOTA-octreotate (LuTate) for neuroendocrine tumours (NET) is now an approved treatment available in many countries, though primary or secondary resistance continue to limit its effectiveness or durability. We hypothesised that a genome-wide CRISPR/Cas9 screen would identify key mediators of response to LuTate and gene targets that might offer opportunities for novel combination therapies for NET patients. Methods: We utilised a genome-wide CRISPR-Cas9 screen in LuTate-treated cells to identify genes that impact on the sensitivity or resistance of cells to LuTate. Hits were validated through single-gene knockout. LuTate-resistant cells were assessed to confirm LuTate uptake and retention, and persistence of somatostatin receptor 2 (SSTR2) expression. Gene knockouts conferring LuTate sensitivity were further characterised by pharmacological sensitisation using specific inhibitors and in vivo analysis of the efficacy of these inhibitors in combination with LuTate. Results: The CRISPR-Cas9 screen identified several potential targets for both resistance and sensitivity to PRRT. Two gene knockouts which conferred LuTate resistance in vitro, ARRB2 and MVP, have potential mechanisms related to LuTate binding and retention, and modulation of DNA-damage repair (DDR) pathways, respectively. The screen showed that sensitivity to LuTate treatment in vitro can be conferred by the loss of a variety of genes involved in DDR pathways, with loss of genes involved in Non-Homologous End-Joining (NHEJ) being the most lethal. Loss of the key NHEJ gene, PRKDC (DNA-PK), either by gene loss or inhibition by two different inhibitors, resulted in significantly reduced cell survival upon exposure of cells to LuTate. In SSTR2-positive xenograft-bearing mice, the combination of nedisertib (a DNA-PK specific inhibitor) and LuTate produced a more robust control of tumour growth and increased survival compared to LuTate alone. Conclusions: DDR pathways are critical for sensing and repairing radiation-induced DNA damage, and our study shows that regulation of DDR pathways may be involved in both resistance and sensitivity to PRRT. Additionally, the use of a DNA-PK inhibitor in combination with LuTate PRRT significantly improves the efficacy of the treatment in pre-clinical models, providing further evidence for the clinical efficacy of this combination.

Development of Highly Potent Clinical Candidates for Theranostic Applications against Cholecystokinin-2 Receptor Positive Cancers

Peptide receptor radionuclide therapy (PRRT) is a promising form of systemic radiation therapy designed to eradicate cancer. Cholecystokinin-2 receptor (CCK2R) is an important molecular target that is highly expressed in a range of cancers. This study describes the synthesis and in vivo characterization of a novel series of 177Lu-labeled peptides ([177Lu]Lu-2b-4b) in comparison with the reference CCK2R-targeting peptide CP04 ([177Lu]Lu-1b). [177Lu]Lu-1b-4b showed high chemical purity (HPLC ≥ 94%), low Log D7.4 (-4.09 to -4.55) with strong binding affinity to CCK2R (KD 0.097-1.61 nM), and relatively high protein binding (55.6-80.2%) and internalization (40-67%). Biodistribution studies of the novel 177Lu-labeled peptides in tumors (AR42J and A431-CCK2R) showed uptake one- to eight-fold greater than the reference compound CP04 at 1, 24, and 48 h. Rapid clearance and high tumor uptake and retention were established for [177Lu]Lu-2b-4b, making these compounds excellent candidates for theranostic applications against CCK2R-expressing tumors.

An immunomodulating peptide to counteract solar radiation-induced immunosuppression and DNA damage

Ultraviolet radiation (UVR) induces immunosuppression and DNA damage, both of which contribute to the rising global incidence of skin cancer including melanoma. Nucleotide excision repair, which is activated upon UVR-induced DNA damage, is linked to expression of interleukin-12 (IL-12) which serves to limit immunosuppression and augment the DNA repair process. Herein, we report an immunomodulating peptide, designated IK14800, that not only elicits secretion of IL-12, interleukin-2 (IL-2) and interferon-gamma (IFN-γ) but also reduces DNA damage in the skin following exposure to UVR. Combined with re-invigoration of exhausted CD4+ T cells, inhibition of UVR-induced MMP-1 release and suppression of B16F10 melanoma metastases, IK14800 offers an opportunity to gain further insight into mechanisms underlying the development and progression of skin cancers.

Automated radiosynthesis of [89Zr]Zr-DFOSq-Durvalumab for imaging of PD-L1 expressing tumours in vivo

OBJECTIVES

⁸⁹Zr-labelled proteins are gaining importance in clinical research in a variety of diseases. To date, no clinical study has been reported that utilizes an automated approach for radiosynthesis of ⁸⁹Zr-labelled radiopharmaceuticals. We aim to develop an automated method for the clinical production of ⁸⁹Zr-labelled proteins and apply this method to Durvalumab, a monoclonal antibody targeting PD-L1 immune-checkpoint protein. PD-L1 expression is poorly understood and can be up-regulated over the course of chemo- and radiotherapy treatment. The ImmunoPET multicentre study aims to examine the dynamics of PD-L1 expression via ⁸⁹Zr-Durvalumab PET imaging before, during, and after chemoradiotherapy. The developed automated technique will enable reproducible clinical production of [⁸⁹Zr]Zr-DFOSq-Durvalumab for this study at three different sites.

METHODS

Conjugation of Durvalumab to H₃DFOSqOEt was optimized for optimal chelator-to-antibody ratio. Automated radiolabelling of H₃DFOSq-Durvalumab with zirconium-89 was optimized on the disposable cassette based iPHASE technologies MultiSyn radiosynthesizer using a modified cassette. Activity losses were tracked using a dose calibrator and minimized by optimizing fluid transfers, reaction buffer, antibody formulation additives and pH. The biological profile of the radiolabelled antibody was confirmed in vivo in PD-L1+ (HCC827) and PD-L1- (A549) murine xenografts. Clinical process validation and quality control were performed at three separate study sites to satisfy clinical release criteria.

RESULTS

H₃DFOSq-Durvalumab with an average CAR of 3.02 was obtained. Radiolabelling kinetics in succinate (20 mM, pH 6) were significantly faster when compared to HEPES (0.5 M, pH 7.2) with >90 % conversion observed after 15 min. Residual radioactivity in the ⁸⁹Zr isotope vial was reduced from 24 % to 0.44 % ± 0.18 % (n = 7) and losses in the reactor vial were reduced from 36 % ± 6 % (n = 4) to 0.82 % ± 0.75 % (n = 4) by including a surfactant in the reaction and formulation buffers. Overall process yield was 75 % ± 6 % (n = 5) and process time was 40 min. Typically, 165 MBq of [⁸⁹Zr]Zr-DFOSq-Durvalumab with an apparent specific activity of 315 MBq/mg ± 34 MBq/mg (EOS) was obtained in a volume of 3.0 mL. At end-of-synthesis (EOS), radiochemical purity and protein integrity were always >99 % and >96 %, respectively, and dropped to 98 % and 65 % after incubation in human serum for 7 days at 37 °C. Immunoreactive fraction in HEK293/PD-L1 cells was 83.3 ± 9.0 (EOS). Preclinical in vivo data at 144 h p.i. showed excellent SUV_max in PD-L1+ tumour (8.32 ± 0.59) with a tumour-background ratio of 17.17 ± 3.96. [⁸⁹Zr]Zr-DFOSq-Durvalumab passed all clinical release criteria at each study site and was deemed suitable for administration in a multicentre imaging trial.

CONCLUSION

Fully automated production of [⁸⁹Zr]Zr-DFOSq-Durvalumab for clinical use was achieved with minimal exposure to the operator. The cassette-based approach allows for consecutive productions on the same day and offers an alternative to currently used manual protocols. The method should be broadly applicable to other proteins and has the potential for clinical impact considering the growing number of clinical trials investigating ⁸⁹Zr-labelled antibodies.

VIOLET: A phase I/II trial evaluation of radioligand treatment in men with metastatic castration-resistant prostate cancer with [161Tb]Tb-PSMA-I&T

TPS281

Background: [177Lu]Lu-PSMA is an effective class of therapy for men with metastatic castration-resistant prostate cancer (mCRPC); however, progression is inevitable. The limited durability of response is partially explained by the presence of micrometastatic deposits. Single tumor cells and micrometastases are energy-sheltered deposits receiving low absorbed radiation, due to the ~0.7mm mean path-length of Lutetium-177 (177Lu). Terbium-161 (161Tb) has abundant emission of Auger electrons that deposit a higher concentration of radiation over a shorter path, particularly to single tumor cells and micrometastases. 161Tb has shown superior in-vitro and in-vivo results in comparison with 177Lu. We hypothesize that [161Tb]Tb-PSMA-I&T will deliver effective radiation to sites of metastatic prostate cancer with an acceptable safety profile. Methods: This single-center, single-arm, phase I/II trial will recruit 30 to 36 men with progressive mCRPC. The phase I dose-escalation is designed with a 3+3 model to establish the safest dose of [161Tb]Tb-PSMA-I&T (dose levels: 4.4, 5.5 and 7.4 GBq). The maximum tolerated dose (MTD) will be defined as the highest dose level at which a dose-limiting toxicity occurs in less than 1/3 or 2/6 participants. The phase II dose-expansion will include 24 participants at the MTD. Up to six cycles of [161Tb]Tb-PSMA-I&T will be administered intravenously every six weeks, with each subsequent dose for each patient reduced by 0.4GBq. Key eligibility criteria include a diagnosis of mCRPC with progression after at least one line of taxane chemotherapy and a second-generation anti-androgen, PSMA-positive disease on PSMA PET/CT (SUVmax ≥20), no sites of discordance on FDG PET/CT, adequate bone marrow, hepatic and renal function, ECOG performance status ≤2, and no prior treatment with another radioisotope. The co-primary objectives are to establish the MTD of [161Tb]Tb-PSMA-I&T, and safety profile [CTCAE v5.0]. Secondary objectives include measuring absorbed radiation dose [Gray], evaluating anti-tumour activity [PSA 50% response rate, radiographic and PSA progression-free survival, overall survival, objective response rate], and evaluation of pain [BPI-SF] and health-related quality of life [FACT-P and FACT-RNT] over the first 12 months after treatment commences. Exploratory objectives include ctDNA analysis at baseline, during treatment and at progression, and optional tissue biopsies, to determine biomarkers of treatment response and resistance. Patient enrolment began in October 2022, with recruitment expected to continue for 24 months. Clinical trial information: NCT05521412 .

ImmunoPET: IMaging of cancer imMUNOtherapy targets with positron Emission Tomography: a phase 0/1 study characterising PD-L1 with 89Zr-durvalumab (MEDI4736) PET/CT in stage III NSCLC patients receiving chemoradiation study protocol

BACKGROUND

ImmunoPET is a multicentre, single arm, phase 0-1 study that aims to establish if ⁸⁹Zr-durvalumab PET/CT can be used to interrogate the expression of PD-L1 in larger, multicentre clinical trials.

METHODS

The phase 0 study recruited 5 PD-L1+ patients with metastatic non-small cell lung cancer (NSCLC). Patients received 60MBq/70 kg ⁸⁹Zr-durva up to a maximum of 74 MBq, with scan acquisition at days 0, 1, 3 or 5±1 day. Data on (1) Percentage of injected ⁸⁹Zr-durva dose found in organs of interest (2) Absorbed organ doses (µSv/MBq of administered ⁸⁹Zr-durva) and (3) whole-body dose expressed as mSv/100MBq of administered dose was collected to characterise biodistribution.The phase 1 study will recruit 20 patients undergoing concurrent chemoradiotherapy for stage III NSCLC. Patients will have ⁸⁹Zr-durva and FDG-PET/CT before, during and after chemoradiation. In order to establish the feasibility of ⁸⁹Zr-durva PET/CT for larger multicentre trials, we will collect both imaging and toxicity data. Feasibility will be deemed to have been met if more than 80% of patients are able complete all trial requirements with no significant toxicity.

ETHICS AND DISSEMINATION

This phase 0 study has ethics approval (HREC/65450/PMCC 20/100) and is registered on the Australian Clinical Trials Network (ACTRN12621000171819). The protocol, technical and clinical data will be disseminated by conference presentations and publications. Any modifications to the protocol will be formally documented by administrative letters and must be submitted to the approving HREC for review and approval.

TRIAL REGISTRATION NUMBER

Australian Clinical Trials Network ACTRN12621000171819.

Tumor immune microenvironment of primary prostate cancer with and without germline mutations in homologous recombination repair genes

BACKGROUND

Aberrations in homologous recombination repair (HRR) genes are emerging as important biomarkers for personalized treatment in prostate cancer (PCa). HRR deficiency (HRD) could affect the tumor immune microenvironment (TIME), potentially contributing to differential responses to poly ADP-ribose polymerase (PARP) inhibitors and immune checkpoint inhibitors. Spatial distribution of immune cells in a range of cancers identifies novel disease subtypes and is related to prognosis. In this study we aimed to determine the differences in the TIME of PCa with and without germline (g) HRR mutations.

METHODS

We performed gene expression analysis, multiplex immunohistochemistry of T and B cells and quantitative spatial analysis of PCa samples from 36 patients with gHRD and 26 patients with sporadic PCa. Samples were archival tumor tissue from radical prostatectomies with the exception of one biopsy. Results were validated in several independent cohorts.

RESULTS

Although the composition of the T cell and B cells was similar in the tumor areas of gHRD-mutated and sporadic tumors, the spatial profiles differed between these cohorts. We describe two T-cell spatial profiles across primary PCa, a clustered immune spatial (CIS) profile characterized by dense clusters of CD4⁺ T cells closely interacting with PD-L1⁺ cells, and a free immune spatial (FIS) profile of CD8⁺ cells in close proximity to tumor cells. gHRD tumors had a more T-cell inflamed microenvironment than sporadic tumors. The CIS profile was mainly observed in sporadic tumors, whereas a FIS profile was enriched in gHRD tumors. A FIS profile was associated with lower Gleason scores, smaller tumors and longer time to biochemical recurrence and metastasis.

CONCLUSIONS

gHRD-mutated tumors have a distinct immune microenvironment compared with sporadic tumors. Spatial profiling of T-cells provides additional information beyond T-cell density and is associated with time to biochemical recurrence, time to metastasis, tumor size and Gleason scores.

Imaging immunity in patients with cancer using positron emission tomography

Immune checkpoint inhibitors and related molecules can achieve tumour regression, and even prolonged survival, for a subset of cancer patients with an otherwise dire prognosis. However, it remains unclear why some patients respond to immunotherapy and others do not. PET imaging has the potential to characterise the spatial and temporal heterogeneity of both immunotherapy target molecules and the tumor immune microenvironment, suggesting a tantalising vision of personally-adapted immunomodulatory treatment regimens. Personalised combinations of immunotherapy with local therapies and other systemic therapies, would be informed by immune imaging and subsequently modified in accordance with therapeutically induced immune environmental changes. An ideal PET imaging biomarker would facilitate the choice of initial therapy and would permit sequential imaging in time-frames that could provide actionable information to guide subsequent therapy. Such imaging should provide either prognostic or predictive measures of responsiveness relevant to key immunotherapy types but, most importantly, guide key decisions on initiation, continuation, change or cessation of treatment to reduce the cost and morbidity of treatment while enhancing survival outcomes. We survey the current literature, focusing on clinically relevant immune checkpoint immunotherapies, for which novel PET tracers are being developed, and discuss what steps are needed to make this vision a reality.

The PP2A-Integrator-CDK9 axis fine-tunes transcription and can be targeted therapeutically in cancer

Gene expression by RNA polymerase II (RNAPII) is tightly controlled by cyclin-dependent kinases (CDKs) at discrete checkpoints during the transcription cycle. The pausing checkpoint following transcription initiation is primarily controlled by CDK9. We discovered that CDK9-mediated, RNAPII-driven transcription is functionally opposed by a protein phosphatase 2A (PP2A) complex that is recruited to transcription sites by the Integrator complex subunit INTS6. PP2A dynamically antagonizes phosphorylation of key CDK9 substrates including DSIF and RNAPII-CTD. Loss of INTS6 results in resistance to tumor cell death mediated by CDK9 inhibition, decreased turnover of CDK9 phospho-substrates, and amplification of acute oncogenic transcriptional responses. Pharmacological PP2A activation synergizes with CDK9 inhibition to kill both leukemic and solid tumor cells, providing therapeutic benefit in vivo. These data demonstrate that fine control of gene expression relies on the balance between kinase and phosphatase activity throughout the transcription cycle, a process dysregulated in cancer that can be exploited therapeutically.

A New Turn in Peptide-Based Imaging Agents: Foldamers Afford Improved Theranostics Targeting Cholecystokinin-2 Receptor-Positive Cancer

Proteins adopt unique folded secondary and tertiary structures that are responsible for their remarkable biological properties. This structural complexity is key in designing efficacious peptides that can mimic the three-dimensional structure needed for biological function. In this study, we employ different chemical strategies to induce and stabilize a β-hairpin fold of peptides targeting cholecystokinin-2 receptors for theranostic application (combination of a targeted therapeutic and a diagnostic companion). The newly developed peptides exhibited enhanced folding capacity as demonstrated by circular dichroism (CD) spectroscopy, ion-mobility spectrometry-mass spectrometry, and two-dimensional (2D) NMR experiments. Enhanced folding characteristics of the peptides led to increased biological potency, affording four optimal Ga-68 labeled radiotracers ([⁶⁸Ga]Ga-4b, [⁶⁸Ga]Ga-11b-13b) targeting CCK-2R. In particular, [⁶⁸Ga]Ga-12b and [⁶⁸Ga]Ga-13b presented improved metabolic stability, enhanced cell internalization, and up to 6 fold increase in tumor uptake. These peptides hold great promise as next-generation theranostic radiopharmaceuticals.

Single-arm prospective interventional study assessing feasibility of using gallium-68 ventilation and perfusion PET/CT to avoid functional lung in patients with stage III non-small cell lung cancer

BACKGROUND

In the curative-intent treatment of locally advanced lung cancer, significant morbidity and mortality can result from thoracic radiation therapy. Symptomatic radiation pneumonitis occurs in one in three patients and can lead to radiation-induced fibrosis. Local failure occurs in one in three patients due to the lungs being a dose-limiting organ, conventionally restricting tumour doses to around 60 Gy. Functional lung imaging using positron emission tomography (PET)/CT provides a geographic map of regional lung function and preclinical studies suggest this enables personalised lung radiotherapy. This map of lung function can be integrated into Volumetric Modulated Arc Therapy (VMAT) radiotherapy planning systems, enabling conformal avoidance of highly functioning regions of lung, thereby facilitating increased doses to tumour while reducing normal tissue doses.

METHODS AND ANALYSIS

This prospective interventional study will investigate the use of ventilation and perfusion PET/CT to identify highly functioning lung volumes and avoidance of these using VMAT planning. This single-arm trial will be conducted across two large public teaching hospitals in Australia. Twenty patients with stage III non-small cell lung cancer will be recruited. All patients enrolled will receive dose-escalated (69 Gy) functional avoidance radiation therapy. The primary endpoint is feasibility with this achieved if ≥15 out of 20 patients meet pre-defined feasibility criteria. Patients will be followed for 12 months post-treatment with serial imaging, biomarkers, toxicity assessment and quality of life assessment.

DISCUSSION

Using advanced techniques such as VMAT functionally adapted radiation therapy may enable safe moderate dose escalation with an aim of improving local control and concurrently decreasing treatment related toxicity. If this technique is proven feasible, it will inform the design of a prospective randomised trial to assess the clinical benefits of functional lung avoidance radiation therapy.

ETHICS AND DISSEMINATION

This study was approved by the Peter MacCallum Human Research Ethics Committee. All participants will provide written informed consent. Results will be disseminated via publications.

TRIALS REGISTRATION NUMBER

NCT03569072; Pre-results.

Potential screening assays for individual radiation sensitivity and susceptibility and their current validation state

Purpose: The workshop on 'Individual Radiosensitivity and Radiosusceptibility' organized by MELODI and CONCERT on Malta in 2018, evaluated the current state of assays to identify sensitive and susceptible subgroups. The authors provide an overview on potential screening assays detecting individuals showing moderate to severe early and late radiation reactions or are at increased risk to develop cancer upon radiation exposure.Conclusion: It is necessary to separate clearly between tissue reactions and stochastic effects such as cancer when comparing the existing literature to validate various test systems. Requirements for the assays are set up. The literature is reviewed for assays that are reliable and robust. Sensitivity and specificity of the assays are regarded and scrutinized for modifying factors. Accuracy of an assay system is required to be more than 90% to balance risks of adverse reactions against risk to fail to cure the cancer. No assay/biomarker is in routine use. Assays that have shown predictive potential for radiosensitivity include SNPs, the RILA assay, and the pATM assay. A tree of risk guideline for radiologists is provided to assist medical treatment decisions. Recommendations for effective research include the setup of common retrospective and prospective cohorts/biobanks to validate current and future tests.

Treatment for non-small-cell lung cancer and circulating tumor cells

Surgery is the main curative therapy for patients with localized non-small-cell lung cancer while radiotherapy (RT), alone or with concurrent platinum-based chemotherapy, remains the primary curative modality for locoregionally advanced non-small-cell lung cancer. The risk of distant metastasis is high after curative-intent treatment, largely attributable to the presence of undetected micrometastases, but which could also be related to treatment-related increases in circulating tumor cells (CTCs). CTC mobilization by RT or systemic therapies might either reflect efficient tumor destruction with improved prognosis, or might promote metastasis and thus represent a potential therapeutic target. RT may induce prometastatic biological alterations in CTC at the cellular level, which are detectable by 'liquid biopsies', though their rarity represents a major challenge. Improved methods of isolation and ex vivo propagation will be essential for the future of CTC research.

The absent cryptorchid testis: surgical findings and their implications for diagnosis and etiology

On surgical exploration for impalpable testes, there is often found nothing or a nubbin of tissue at the end of the spermatic vessels. This situation is commonly referred to as an absent testis. Controversy exists on how to establish correctly this diagnosis and the degree of investigation required. In addition, there is disagreement concerning whether an absent testis results from early torsion or endocrinopathic event. What is accepted is that the spermatic vessels are singularly important in establishing testis location. In this study, the pathological findings of 117 cases of absent testis diagnosed by surgical exploration at our hospital were reviewed. This diagnosis represented 10% of 1,225 patients explored for cryptorchidism from 1985 to 1991. Average patient age at operation was 26.8 months (range 5 months to 14 years). Of these children 78 (67%) presented with an impalpable left testis. At operation 3 patients (3%) underwent laparoscopy only, while all others had groin exploration with or without transperitoneal exposure to ensure identification of spermatic vessels. In 110 cases surgical specimens or nubbins were excised. Pathological study of these remnants revealed vas deferens in 89 cases (81%), epididymal tissue in 40 (36%) and small amounts of seminiferous tubules with germinal elements in 7 (6.4%). Only 26 specimens (24%) had sufficient vascular tissue present to be suggestive of spermatic vessels. A significant number showed the presence of calcification (35.5%) and hemosiderin (30%) deposits within the remnant. A subset of patients with absent testis possesses testicular tissue of presumed increased malignant potential. Therefore, surgical exploration with spermatic vessel identification and remnant removal is the gold standard for the diagnosis and treatment of the absent testis. The surgeon continues to be responsible for spermatic vessel identification, since the vessels may be recognized at pathological examination in less than 25% of the cases. Also, the common finding of calcification and hemosiderin lends weight to the torsion etiology over endocrinopathy for an absent testis.

Endoscopic incision of ureteroceles: intravesical versus ectopic

A total of 51 children, mostly less than 2 years old, underwent endoscopic incision of ureteroceles as a primary form of treatment. In 73% no further surgery was required. Of the patients 19 were diagnosed by prenatal ultrasound, with a urinary tract infection the usual presenting symptom in the remainder. Of 27 intravesical cases endoscopic incision resulted in decompression of the ureterocele in 93%, with preservation of upper pole function in 96%, and secondary surgical procedures were required in 7%. Reflux was created in 18% and it persisted in 2 of 4 patients. Of 24 cases of ectopic (extravesical) ureteroceles incision resulted in decompression in 75%, with upper pole function preserved in 50%. Reflux was created in 47% and a secondary surgical procedure was performed in 50%. Preservation of upper pole function was significantly better for intravesical versus ectopic ureteroceles (p < 0.01), and the requirement for secondary surgical procedure was greater with ectopic ureteroceles (p < 0.01). Three patients had intermittent bladder outlet obstruction following the incision and required further surgery. The 2 different techniques for incision of intravesical and ectopic ureteroceles are described. The role of endoscopic incision in the overall management of ureteroceles is confirmed by this review, and the need for partial nephroureterectomy may diminish.

Urethral stones: US for identification in boys with hematuria and dysuria

There are multiple causes for hematuria in infants and children. When hematuria is accompanied by dysuria, however, one should focus attention on the lower urinary tract. Although ultrasound (US) is a well-established method for assessing the kidneys and bladder, little attention has been focused on its use for evaluating urethral abnormalities, since voiding cystourethrography or retrograde urethrography usually is used. In the cases of two young boys, sonography aided in the identification of clinically unsuspected urethral stones. US evaluation of the urethra is now included as an integral part of urinary tract sonography in male patients with hematuria accompanied by dysuria.

Managing apparent ureteropelvic junction obstruction in the newborn

A total of 97 newborns with apparent ureteropelvic junction obstruction was evaluated from mid 1984 to 1989. Evaluation and management are described. Of these patients 39 with an affected kidney showing good initial differential function (greater than 35%) by diethylenetriaminepentaacetic acid scan and 2 showing diminished function (less than 35%) were followed nonoperatively. Six patients (15%) eventually required pyeloplasty for diminishing function (4), urinary tract infections (1) or symptoms of colic (1). The 4 patients with diminishing function improved after pyeloplasty to at least the initial level. A total of 12 patients with good initial function (greater than 35%) of the affected kidney underwent early pyeloplasty (within 6 weeks of diagnosis). They were compared to the similar group of patients managed nonoperatively and followed by sequential renal scans. Eventual changes in percentage differential function in the nonoperative and early surgery groups were +2.8% and +4.1%, respectively. Changes in extraction factor were +0.8% (nonoperative group) and +0.9% (surgery group). No statistically significant difference was found. In the kidney with apparent ureteropelvic junction obstruction and good function, an initial nonoperative approach with sequential renal scan followup and pyeloplasty as needed appears to be reasonable and has resulted in no permanent loss of function.

An Absent Testis is Associated with Contralateral Testicular Hypertrophy

Surgical exploration was done in 109 boys ages birth through 9 years with unilateral impalpable testes by physical examination under anesthesia. Of the patients 51 (47%) had an absent testis and 58 had intra-abdominal testes. At open biopsy of the contralateral descended testis the 3 dimensions of the exposed testis were recorded and testicular volume was calculated. The mean volume of the contralateral descended testes of boys with an absent testis was greater than that of boys with intra-abdominal testes at all ages. The differences were significant (p = 0.0019 to 0.0117) from birth through year 4 but not from years 5 through 9. However, the standard deviations ranged from 27 to 74% of the means, and there was broad overlap of the volumes of the 2 groups. These findings indicate that, although the volume of the contralateral descended testis of boys with an absent testis is significantly greater than that of boys with intra-abdominal testes, the volume of the contralateral descended testis is not a reliable criterion for differentiating an absent testis from an intra-abdominal testis in a boy with a unilateral impalpable testis. Surgical exploration continues to be the method of choice for making the diagnosis of an absent testis.

Is lamina propria matrix responsible for normal bladder compliance?

Immunohistochemistry using monoclonal and polyclonal antibodies to extracellular matrix proteins is a highly sensitive tool for the characterization of matrix components. For the first time in the normal and noncompliant human bladder we have used antibodies to collagen types I, III and IV, and elastin to provide morphological correlation with mechanical properties noted clinically. In the normal bladder elastin and collagen types I and III showed intense localization in the lamina propria with modest localization in the detrusor layer. In contrast, lamina propria staining in the noncompliant bladder was essentially unchanged, while there was intense localization within the detrusor layer. Significantly, this intense localization consisted of collagen type III and elastin with little increase in type I. Type IV collagen is associated with basement membranes and individual smooth muscle cells, and shows commensurate increase in specimens with muscle hypertrophy and/or hyperplasia. These observations suggest that in the normal bladder the lamina propria may be a major structural capacitance layer with the smooth muscle covering it. The collagen fibers of the lamina propria may gradually unfold during filling, thus, accounting for normal compliance while in the noncompliant bladder the capacitance layer shifts outward to the infiltrated smooth muscle, thus, preventing the normal expansion of the lamina propria. The smooth muscle infiltration consists of a deposition of collagen type III and elastin with little increase of collagen type I, and it results in a loss of compliance. The pattern of localization would suggest that the smooth muscle is responsible for this accumulation.

Lithogenic properties of enterocystoplasty

Calculi formed in 26 of 87 patients (30%) following augmentation enterocystoplasty, of which 23 formed within the reservoir, at a mean interval of 25 months postoperatively. The calculi were composed principally of triple phosphates suggesting an important etiological role of bacteriuria and the urease reaction. Open cystolithotomy was the most successful means of removing the calculi.

Early postnatal testicular maldevelopment in cryptorchidism

It has been previously postulated that many cases of cryptorchidism are manifestations of a forme fruste of hypogonadotropic hypogonadism. In support of this theory the earliest postnatal histological abnormality in cryptorchid testes demonstrated by this morphometric study of semithin microscopic sections of testicular biopsies was hypoplasia of the Leydig cells, which was obvious from the first month of life. The second abnormality, defective transformation of gonocytes into adult dark spermatogonia, was significant from early in life. No reduction in the mean number of germ cells was detected in the first 7 months of life. The abnormal persistence of the untransformed gonocytes resulted in a total germ cell count that was similar to normal controls until the seventh month, when secondary degeneration of untransformed gonocytes led to a decrease in the total germ cell count. These findings are compatible with the hypothesis that the blunted neonatal surge of gonadotropins previously demonstrated in cryptorchid boys triggers a cascade of hormonal and secondary histological abnormalities that may culminate in a reduced fertility potential in adults. Early replacement hormonal therapy deserves further investigation as a rational approach to the treatment of germ cell maldevelopment and reduced fertility potential associated with cryptorchidism.

Gonadal differentiation: a review of the physiological process and influencing factors based on recent experimental evidence

The sexual differentiation of a gonad is determined in normal embryology by the presence or absence of the TDF gene, a short segment of DNA localized near the tip of the short arm of the Y chromosome. Under the stimulus of this gene, the somatic cells of the genital ridge differentiate into Sertoli cells and secrete anti-müllerian hormone. This hormone inhibits the germ cells from entering meiosis and may well also trigger the formation of the primary sex cords. Once the Sertoli cells are formed, further differentiation of the gonad is independent of the TDF presence, although this gene may further contribute to the normal functioning of the male gonad. In true hermaphroditism the normal regulation of the gonadal differentiation is missing. Gonadal differentiation may revert to a more primitive evolutionary level at which the rate of growth of the gonad determines its sexual direction. When this exceeds a certain threshold a testis may develop despite the absence of the TDF gene.

Paratesticular rhabdomyosarcoma: results of therapy in 18 cases

The management of paratesticular rhabdomyosarcoma has evolved more slowly than that for testicular germ cell tumors, mainly due to its lower incidence and the lack of standardized treatment protocols. With gradual refinements in staging and therapy the prognosis has improved. Between 1960 and 1988, 18 patients 2 to 18 years old were treated at the Children's Hospital. Management consisted of inguinal orchiectomy, staging evaluation and retroperitoneal lymph node dissection, followed by chemotherapy and radiotherapy according to the stage of the disease. In 11 patients (61%) the disease was confined to the scrotum, while 7 presented with spread to the retroperitoneal lymph nodes, including 3 children with more distant metastases. Histological study revealed predominantly embryonal characteristics except for 1 alveolar cell type. Chemotherapy consisted of actinomycin D in 2 patients, vincristine, actinomycin D and cyclophosphamide in 2, pulse vincristine, actinomycin D and cyclophosphamide in 10, and doxorubicin plus vincristine, actinomycin D and cyclophosphamide in 4. A total of 17 patients remain free of disease (median followup 4 years) with 1 death. The actuarial survival without relapse and over-all survival rate are 89 and 94%, respectively. We conclude that paratesticular rhabdomyosarcoma represents a favorable subgroup of rhabdomyosarcoma.

Prognosis of patients with stage D1 prostate carcinoma following radical prostatectomy with and without early endocrine therapy

Early endocrine therapy after radical retropubic prostatectomy was compared to radical prostatectomy alone (nonearly endocrine therapy) for the treatment of carcinoma of the prostate with lymph node metastases. Our retrospective analysis demonstrated that the 2 cohorts were similar with respect to patient age, Gleason sum score, seminal vesicle invasion, lymph node involvement, tumor volume and pathological stage of the primary tumor. The cause-specific survival of the entire group was 84% at 60 months and 78% at 98 months. The cause-specific curves for the early and nonearly endocrine therapy group were not significantly different (p less than 0.194), although the estimated 9-year survival rates were 91 and 71%, respectively. Survival free of disease was significantly prolonged in the early endocrine therapy group (p less than 0.030), with a 9-year estimated rate free of disease of 67% versus 32% in the nonearly endocrine therapy group. Followup prostate specific antigen serum levels were analyzed and the value as a progression marker is discussed. These data suggest that a radical operation plus early endocrine therapy is effective palliation in selected patients with low volume lymph node metastases, producing clinical survival free of disease in most patients.

An improved model of recurrent herpetic eye disease in mice

Mice were passively immunized with serum containing antibodies to herpes simplex virus type 1 (HSV-1) before inoculation on the cornea with HSV-1 strain McKrae. After such immunization most mice survived and most had normal eyes. When primary infection had subsided, mice with normal eyes were selected and treated with cyclophosphamide, dexamethasone and UV irradiation of the inoculated eye or UV irradiation alone, to reactivate latent virus. After either treatment mice developed signs of recurrent infection (virus in eyewashings and recurrent corneal and/or lid disease). The incidence of such signs was 17/33 (52%) in mice receiving immunosuppressive drugs and UV irradiation and 19/32 (59%) in mice given UV irradiation alone. In mice treated with either stimulus dendritic or geographic ulceration of the cornea was seen. These closely resembled the herpetic lesions seen in humans. There was good correlation between the pattern and distribution of recurrent corneal disease and the distribution of cells containing virus antigens in corneal epithelial sheets. Again, as in humans, the induction of recurrent infection was found to correlate poorly with a rise in the level of serum neutralizing antibody. In mice treated with UV irradiation alone corneal ulcers healed and the eyes returned to normal. By contrast, in mice given immunosuppressive drugs and UV irradiation, the ulceration became more severe and the eyes became opaque and vascularized. The use of passive immunization has greatly improved our previously reported model of recurrent herpetic eye disease since it has increased the incidence of mice suitable for the induction of recurrent infection and has increased the incidence of such infection.

Prognostic significance of the DNA content of renal carcinoma

DNA analysis was performed on fresh frozen samples of the primary tumor in 32 patients with renal carcinoma (13 with apparently localized disease and 19 with metastases at presentation). A comparison of ploidy with staging and standard histologic variables was performed. None of the patients who presented without metastases died of disease during the follow-up period. Eleven of 13 patients of this group had a diploid/near diploid pattern, and metastases developed in only one patient. Patients with metastatic disease and a diploid/near diploid DNA content had a significantly better survival rate than those with aneuploid primary tumors. Statistical analysis showed that grade and ploidy contributed significant but independent prognostic information. We concluded that DNA content is a useful prognostic factor in renal carcinoma.

Effect of stilboestrol on sodium balance, cardiac state, and renin-angiotensin-aldosterone activity in prostatic carcinoma

A prospective study examined the sequential effects of diethylstilboestrol (stilboestrol) on sodium balance, cardiac state, and renin-angiotensin-aldosterone activity in six patients with metastatic carcinoma of the prostate. Whereas metabolic balance studies did not show evidence of sodium retention during the first seven days of treatment, there was a significant and progressive increase in plasma volume after three months (mean increase 541 ml; p less than 0.01). Stilboestrol increased supine plasma renin and angiotensin II values but the response of renin-angiotensin-aldosterone activity to erect posture was progressively reduced during treatment. No significant changes in blood pressure or indices of cardiac function occurred during the three months of observation. The findings of increased basal renin-angiotensin-aldosterone activity and an increase in plasma volume suggest an important mechanism of the cardiac complications associated with oestrogen treatment.

Tracheo-oesophageal fistula in Christchurch: a review

The management of tracheo-oesophageal fistulae at Christchurch from 1968-1982 has been reviewed. Thirty-one cases have been diagnosed with 26 undergoing surgery. There has been an overall mortality of 48% but there was a trend towards improved survival figures. Other congenital anomalies were present in 56%. Oesophageal stenosis occurred in four of the operative cases and led to major problems in management.

The outcome of severe head injuries

Twenty-eight patients who had survived severe head injury were studied. Although sixteen achieved 'good recovery' status, they, and their families, had to surmount many difficulties, and persisting physical deficits, substantial personality changes, and disruptions to family relationships were distressing continuing problem for many.