Utilizing clinical, pathological and radiological information to guide postoperative radiotherapy in prostate cancer

INTRODUCTION

A detectable and rising PSA following radical prostatectomy is indicative of recurrent prostate cancer. Salvage radiotherapy (SRT) with/without androgen deprivation therapy represents the main treatment option for these patients and has been historically associated with a biochemical control rate of ~70%. To determine the optimal timing, diagnostic workup, radiotherapy dosefractionation, treatment volume, and use of systemic therapy, several informative studies have been conducted in the last decade.

AREAS COVERED

This review examines the recent evidence to guide radiotherapy decision making in the SRT setting. Key topics include adjuvant vs salvage RT, utilization of molecular imaging and genomic classifiers, length of androgen deprivation therapy, inclusion of elective pelvic volume, and emerging role for hypofractionation.

EXPERT OPINION

Recently reported trials, conducted in an era prior to the routine use of molecular imaging and genomic classifiers, have been pivotal in establishing the current standard of care for SRT in prostate cancer. However, decisions about radiation treatment and systemic therapy may be tailored based on available prognostic and predictive biomarkers. Data from contemporary clinical trials are awaited to define and establish individualized, biomarker-driven approaches for SRT.

Abstract PR014: Cytokine mediated epigenetic reprogramming of CRC primary tumors drives liver metastasis

An emerging hypothesis is that metastatic potential is determined largely by the combination of genetic alterations that initiate the primary tumor and subsequent transcriptional reprogramming through epigenetic mechanisms. Here we leverage integrative, multi-omic profiling of primary and metastatic colorectal cancer tumors in combination with functional screens and disease models to understand drivers of liver metastasis. Through performing bulk and single cell RNA-sequencing, whole exome sequencing, and H3K27Ac ChIP-seq of primary tumors and metastatic lesions in the liver, we identified dramatic enhancer remodeling in metastatic disease. In specific, we identified a region on chromosome 20 upstream of the signaling protein SIRPA containing 7 differentially active enhancers in metastatic disease. Not only do the enhancers show an in silico enrichment for TCF7 binding sites but we showed them in vitro to be reliant upon TCF7 through the use of a reporter system. To confirm the regulatory potential of TCF7 on SIRPA we performed CRISPRa mediated overexpression of TCF7. This resulted in significant increase in SIRPA levels. We then showed each gene to be functional drivers of metastasis and migration with in vitro and in vivo models. Through CRISPR mediated KO and CRISPRa mediated overexpression, we showed both genes to be necessary and sufficient for migration in a wound healing assay and invasion in a transwell assay. When the lines were transplanted orthotopically to the cecum, we saw a reduction in metastatic burden in the liver with the loss of either gene. To identify liver microenvironmental factors that lead to the upregulation of TCF7 and subsequent activity of SIRPA we assayed conditioned media derived from immortalized hepatocytes. Through the use of a cytokine array, we have shown the hepatocyte produced CCL2 is able to induce TCF7 and subsequently SIRPA in a panel of CRC cell lines and organoids. Importantly we showed the continued production of CCL2 is important for the survival of the cancer cell in the liver microenvironment through both genetic and drug intervention experiments. Together this data indicates an important signaling node in colorectal cancer metastasis to the liver. Here we propose a model in which secreted liver factors, such as CCL2, reprogram genes within the tumor cell to promote growth and survival of the liver. These genes, SIRPA, and TCF7, represent potential therapeutic targets. Targeting these proteins may kill existing metastatic lesions as well as block new metastases from forming which will be important in improving the outcomes of patients with oligometastatic and premetastatic disease.

Citation Format: Jonathan Rennhack, Arika Dwivedi, Nathan Wu, Brian Shim, Alba Font-Tello, Nikolas Kesten, Andrew Aguirre, Henry Long, Kimmie Ng, William C. Hahn. Cytokine mediated epigenetic reprogramming of CRC primary tumors drives liver metastasis [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR014.

VRK1 as a synthetic lethal target in VRK2 promoter-methylated cancers of the nervous system

Collateral lethality occurs when loss of a gene/protein renders cancer cells dependent on its remaining paralog. Combining genome-scale CRISPR/Cas9 loss-of-function screens with RNA sequencing in over 900 cancer cell lines, we found that cancers of nervous system lineage, including adult and pediatric gliomas and neuroblastomas, required the nuclear kinase vaccinia-related kinase 1 (VRK1) for their survival in vivo. VRK1 dependency was inversely correlated with expression of its paralog VRK2. VRK2 knockout sensitized cells to VRK1 loss, and conversely, VRK2 overexpression increased cell fitness in the setting of VRK1 loss. DNA methylation of the VRK2 promoter was associated with low VRK2 expression in human neuroblastomas and adult and pediatric gliomas. Mechanistically, depletion of VRK1 reduced barrier-to-autointegration factor phosphorylation during mitosis, resulting in DNA damage and apoptosis. Together, these studies identify VRK1 as a synthetic lethal target in VRK2 promoter-methylated adult and pediatric gliomas and neuroblastomas.

Abstract 2147: Synthetic lethality of VRK1 in VRK2-methylated cancers

Paralogs are a source of synthetic lethal interactions which lend themselves to novel bio-marker linked targeted therapeutics. From genome-wide essentiality measurements in over 900 cancer cell lines, we find VRK1 dependency in VRK2-methylated adult and pediatric gliomas and neuroblastomas. VRK2 methylation was mainly seen in IDH-mutant gliomas and H3.3-G34R-mutant DIPG. Knockout of VRK2 was able to sensitize cells to VRK1 knockout. Overexpression of kinase-active but not kinase inactive VRK2 rescued VRK1 knockout. Global phosphoproteomics in VRK1 and VRK2 knockout cells demonstrate increased phosphorylation of targets involved with DNA damage and decreased phosphorylation of nuclear membrane targets. VRK1 and VRK2 were found to phosphorylate BANF1, which is involved in nuclear membrane re-formation during mitosis. Taken together, we show that VRK1 is a viable target in VRK2-methylated adult and pediatric gliomas, and neuroblastomas.

Citation Format: Jonathan So, Nathaniel Mabe, Bernhard Englinger, Jason Kwon, Brian Shim, Mariella Filbin, Kimberly Stegmaier, William Hahn. Synthetic lethality of VRK1 in VRK2-methylated cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2147.

IL-7 shapes a multifaceted CD8 T cell response to airway Influenza/A infection

The lungs are a site vulnerable to diseases such as cancer, autoimmunity and infections. With each breath, we risk inhaling infectious agents, and as such, airborne diseases are the leading cause of infectious disease-related deaths in the world. In particular, various strains of Influenza virus can infect airway epithelial cells and activate a network of immune cells leading to clearance, or in cases of pandemic strains, an overzealous response that can be fatal.

Adaptive immune cells, particularly cytotoxic CD8 T cell lymphocytes, play a crucial role in controlling viral replication by killing infected cells. Therefore, tight regulation of the cytokines that lead to the proper activation, proliferation and function of these immune cells is necessary to clear infections efficiently while minimizing damage to the host. Interleukin-7 (IL-7) is a cytokine known for its importance in T cell development and survival. While the function of IL-7 in T cell survival is well characterized, how IL-7 shapes T cell effector responses when a pathogen is encountered is less understood.

Using IL-7Rα hypomorph mice in chimeric and adoptive transfer experiments we have found that IL-7 is cell-intrinsically important for the priming of antigen specific CD8 T cells in the draining lymph nodes. We found that IL-7 dictates terminal differentiation, cytokine production and degranulation of CD8 T cells locally in the airways. Drugs that manipulate IL-7 signaling are currently under clinical trial for multiple conditions. Our findings on IL-7 and its effects on lower respiratory diseases will be necessary for expanding the utility of these therapeutics.

Activation of neonatal mouse lung ILC2s by endogenous IL-33 impacts type 2 responses later in life

Neonatal lung immunity is functionally distinct from adults as responses to environmental antigens are predominantly type 2 biased, and early exposure has been linked to the development of airway allergic diseases. Recently our lab and others have shown that endogenous release of IL-33 due to the stresses of the first few breaths of life leads to expansion and activation of group 2 innate lymphoid cells (ILC2s) from 10 days (D10) to two weeks after birth. However, the amount of IL-33 is lower than in allergen-treated lungs of adult mice, and neonatal lungs do not show signs of type 2 inflammation. Nevertheless, our analyses of IL-33KO and ILC2 deficient pups have suggested that the activation of neonatal lung ILC2s by endogenous IL-33 drives type 2 immunity. As well, neonatal ILC2s labeled with BrdU persist in adulthood. Therefore, we further characterized neonatal lung ILC2s and investigated the effects of neonatal activation on ILC2 functions later in life. Our microarray analysis of neonatal ILC2s showed more similarity to IL-33 activated than naïve adult ILC2s. D10 ILC2s have a high expression of IL-25R, similar to activated adult ILC2s, and can be stimulated by IL-25. We compared IL-33KO and WT ILC2s in adult mice and there was no difference in the phenotype or number of lung ILC2s. However, intranasal (IN) IL-33 injections induced significantly fewer IL-5+IL-13+ ILC2s in IL-33KO mice. We then injected IL-33 into IL-33KO neonates to test the effect on adult ILC2s. Preliminary results show that IN IL-33 into neonatal IL-33KO mice rescue the impaired response of adult IL-33KO ILC2s. These results suggest that the weak activation by the endogenous IL-33 of neonatal lung ILC2s has significant effects on the development of type 2 responses later in life.

Prognostic significance of metabolic adaptation for hypoxic environment in oral squamous cell carcinoma

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Background: During tumor growth, tumor adapts the hypoxic environment and increases glycolysis. This metabolic switch is related to the aggressive malignant behavior. We investigated the connection between the biomarkers related to the glycolytic metabolism (HIF-1α, PDK-1, LDH-5) and clinicopathologic characteristics in oral cavity and oropharynx squamous cell carcinoma (SCC). Methods: Eligibility criteria was the patients diagnosed oral SCC, received curative radical resection and had available tissue samples. Immunohistochemical stain of the HIF-1α, PDK-1, and LDH-5 was done. Statistical analysis was performed to compare biomarkers between patients and time point. Results: Overall 74 patients were enrolled and stage grouping of the patients was as follows: stage I, 25 (33.8%) patients; stage II 17 (23.0%); stage III 8 (10.8%); stage IV 24 (32.4%). 25 patients were relapsed and 5-year disease-free survival (DFS) rate was 61.4%. High expression of HIF-1α was related to the advanced T stage (p = 0.029), more invasive tumor (p = 0.003) and tumor recurrence (p = 0.037). High expression of PDK-1 was related to the advanced N stage (p = 0.026) and high expression of LDH-5 was related to the lymphatics invasion (p = 0.028), advanced N stage (p = 0.020) and more invasive tumor (p = 0.015). The high expression of HIF-1α, PDK-1, and LDH-5 showed a significant correlation to each other. 16 (21.6%) patients were highly expressed all three markers. High expression of all three markers correlated with more invasive tumor (p = 0.004) and tumor recurrence (p = 0.017). In survival analysis, high expression of HIF-1α and LDH-5 associated with shorter DFS in log rank test (p = 0.002 and p = 0.016, respectively). High expression of all three markers was also associated with shorter DFS (p = 0.002). In multivariate Cox regression analysis, high expression of all three markers was strong independent prognostic factor for DFS (p = 0.021). Conclusions: The oral SCC which glycolytic metabolism was changed showed a more invasive and aggressive phenotype. Taken together, biomarkers related tumor metabolism may be independent prognostic markers for the DFS in the patients with oral SCC.

No significant financial relationships to disclose.

Incidence and prevalence of brain metastases among patients with advanced breast cancer in a United States managed-care population

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Background: There continues to be uncertainty about the extent of the breast cancer (BC) population afflicted with secondary brain metastases (BM). This study estimated the incidence and prevalence of BM among patients with advanced BC in a US-based population. Methods: Female BC patients diagnosed with secondary BM between 1/2002 and 12/2004 and with a brain or head diagnostic test within 30 days of the BM diagnosis were identified from a nationally representative private payer database (PharMetrics, Inc.). The date of the first BM diagnosis served as the index date. A 1-year look-back period was used to identify patients with a diagnosis of BC and those with and without a history of BM. Patients were required to have continuous health plan enrollment for 1 year prior to and at least 1 month following the index date. Patients aged <18 years, and those aged 65+ and not in a Medicare Risk plan were excluded. The denominator for incidence and prevalence calculations included all patients with diagnosed advanced BC during the study period. A death proxy algorithm was used to estimate the mortality rate. Results: 779 incident and 995 prevalent BM patients were identified; mean age of each cohort was 53 years. In the 1 year prior to the index diagnosis, 73.6% of incident patients were treated with chemotherapy and 25.0% received radiation therapy; <10% of patients had a lumpectomy, mastectomy, or lymph node dissection. About 22% of incident patients died during the follow-up period, an average of 158 days (95% CI=131.1, 183.9) from the index BM diagnosis. From 2002–2004, 8,518 advanced BC patients were identified, resulting in a BM incidence rate of 9.1% (95% CI=8.5%, 9.8%). During this same period, the prevalence of BM was found to be 11.7% (95% CI=11.0%, 12.4%), with rates increasing by year. On average, the first diagnosis of BM occurred 123 days (95% CI=106.9, 139.3) following the BC diagnosis. Conclusions: Secondary BM is a common occurrence among advanced BC patients. The BM incidence rate is in the range (5–20%) of previously published studies. The prevalence of BM was 28% higher than the incidence and increased over time. This increasing frequency suggests an unmet need that could be filled with newer treatments that improve BC outcomes, including the prevention or delay of BM.

No significant financial relationships to disclose.

Economic burden of brain metastases in breast cancer patients in a US managed-care population

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Background: Limited data are available evaluating health resource use and costs of breast cancer (BC) patients who develop secondary brain metastases (BM). This study estimated the economic burden among BC patients diagnosed with incident BM. Methods: Female BC patients aged 18+ years, newly diagnosed with BM between 1/2002 and 12/2004 were identified from a private payer database (PharMetrics, Inc). The index date was the date of the incident BM diagnosis. BC was identified during a 1-year look-back period. BM patients were matched to a control group of BC patients with no evidence of BM during the study period. Patients not continuously enrolled in a health plan for 1 year before and at least 1 month after the index date and those aged 65+ years and not in Medicare Risk were excluded. Paid claims were used to estimate resource utilization and costs. Results: 775 incident and control patients resulted from a 1:1 match (mean age=54 years). At 6 months follow-up (N=398), BM patients had significantly more hospital stays (mean 1.1 vs. 0.5, p<0.001) and remained hospitalized for a longer period (mean 8.0 days vs. 2.5 days, p<0.001) compared to controls. BM patients also averaged more outpatient services, including physician office visits (32.8 vs. 24.3, p<0.001), as well as pharmacy claims (56.0 vs. 39.1, p<0.001). Similar differences were found at 1 year (N=230), with greater mean inpatient, outpatient, and pharmacy services (p<0.001) in BM patients. Average total costs for BM patients at 6 months were $60,045 compared to $28,193 (p<0.001) for controls; this difference was driven by higher mean inpatient ($17,462 vs. $5,362, p<0.001) and outpatient ($26,209 vs. $11,652, p<0.001) costs among BM patients. At 1 year, higher mean total costs persisted in BM patients ($99,899 vs. $47,719, p<0.001). After adjusting for key variables, mean costs for BM patients were 123% higher than those for control group patients. Conclusions: Patients with BC and secondary BM incurred significantly more healthcare resources following diagnosis compared to those with BC but no BM. Mean total costs for BM patients were more than double those of patients without BM at 6 months and 1 year. These findings underscore important economic implications of BM and the call for new therapies that improve outcomes in patients with BM.

No significant financial relationships to disclose.

Enhanced harmonic generation from expanding clusters

We report controlled enhancement of optical third harmonic generation (THG) from hydrodynamically expanding clusters of approximately 6x10(5) noble-gas atoms several hundred femtoseconds following ionization and heating by ultrashort pump pulses. This resonant enhancement is more pronounced for orthogonal than for parallel pump-probe polarizations, a consequence of faster cluster expansion along the pump polarization. Simulations show that the nonlinear susceptibility chi(3) of the individual clusters and the coherence length of the clustered plasma medium are optimized nearly simultaneously as the clusters expand, and both contribute to the observed THG enhancement. This dual enhancement mechanism may be scalable to relativistic probe intensity and to generation of high-order harmonics in the soft-x-ray regime.

Mechanical and heat sensitization of cutaneous nociceptors in rats with experimental peripheral neuropathy

This study examined whether or not the properties of cutaneous nociceptive fibers are altered in the neuropathic state by comparing lumbars 5 and 6 spinal nerve ligation (SNL) rats with sham-operated controls. The rats with the unilateral SNL developed mechanical allodynia in the ipsilateral hind limb, whereas the sham group did not. Two to 5 weeks after the neuropathic or sham surgery, rats were subjected to single fiber-recording experiments to examine the properties of afferent fibers in the sural and plantar nerves. A total of 224 afferents in the C- and Adelta-ranges were characterized in the neuropathic and sham groups. Spontaneous activity was observed in 16 of 155 fibers in the neuropathic group and one of 69 fibers in the sham group. The response threshold of both the C- and Adelta-fibers to mechanical stimuli was lower in the neuropathic group than the sham group. The afferent fibers responsive to heat stimuli were all C-fibers, and none were Adelta-fibers. The response threshold of the C-fibers to the heat stimuli was lower in the neuropathic group than the sham group. The magnitude of the responses of both C- and Adelta-fibers to the suprathreshold intensity of the mechanical stimulus was greater in the neuropathic group than the sham group. However, the magnitude of the responses of C-fibers to the suprathreshold intensity of the heat stimulus in the neuropathic group was not different from that in the sham group. These results suggest that after a partial peripheral nerve injury, the nociceptors on the skin supplied by an uninjured nerve become sensitized to both mechanical and heat stimuli. This nociceptor sensitization can contribute to neuropathic pain.

The effect of Theiler's murine encephalomyelitis virus (TMEV) VP1 carboxyl region on the virus-induced central nervous system disease

Members of the Theiler's murine encephalomyelitis virus GDVII subgroup, which includes GDVII strain, are highly neurovirulent and induce a rapidly fatal polioencephalomyelitis. By contrast, Theiler's original subgroup members, which includes DA strain, are not as neurovirulent, and produce a chronic, demyelinating disease with virus persistence. We investigated the importance of the carboxyl region of the capsid protein VP1 in TMEV-induced disease since a trypsin-cleavable immunodominant neutralization epitope is situated in the VP1 carboxyl region, and since this region is believed to lie adjacent to the putative receptor binding site. The present studies support the role of DA VP1 residue 268 (and the aligned GDVII VP1 270) in Theiler's murine encephalomyelitis virus-induced CNS disease; however, the effect of this residue varies depending on its context: mutation of DA VP1 268 attenuates demyelination; mutation of GDVII VP1 270 in a GDVII/DA recombinant virus has no effect on demyelination but reduces early deaths (neurovirulence); mutation of GDVII VP1 270 in GDVII virus has no effect on neurovirulence. These data suggest that DA VP1 268/GDVII VP1 270 are not functionally equivalent and that a residue in recombinant viruses can differ in function from the same residue situated in a parental strain. Additional mutagenesis studies suggest that: the trypsin cleavage site of TMEV, which affects virus viability, is located at the lysine at DA VP1 261 (GDVII VP1 263); GDVII VP1 276, the predicted carboxyl terminus of VP1, affects VP1/2A processing and virus infectivity.

Chimeric cDNA studies of Theiler's murine encephalomyelitis virus neurovirulence

Strain GDVII and other members of the GDVII subgroup of Theiler's murine encephalomyelitis virus are highly neurovirulent and rapidly fatal, while strain DA and other members of the TO subgroup produce a chronic, demyelinating disease. GDVII/DA chimeric cDNA studies suggest that a major neurovirulence determinant is within the GDVII 1B through 1D capsid protein coding region, although the additional presence of upstream GDVII sequences, including the 5' untranslated region, contributes to full neurovirulence. Our studies indicate that there are limitations in precisely delineating neurovirulence determinants with chimeric cDNAs between evolutionarily diverged viruses, such as GDVII and DA.