Genetic and immune landscape evolution in MMR-deficient colorectal cancer.

Mismatch repair-deficient (MMRd) colorectal cancers (CRCs) have high mutation burdens, which make these tumours immunogenic and many respond to immune checkpoint inhibitors. The MMRd hypermutator phenotype may also promote intratumour heterogeneity (ITH) and cancer evolution. We applied multiregion sequencing and CD8 and programmed death ligand 1 (PD-L1) immunostaining to systematically investigate ITH and how genetic and immune landscapes coevolve. All cases had high truncal mutation burdens. Despite pervasive ITH, driver aberrations showed a clear hierarchy. Those in WNT/ß-catenin, mitogen-activated protein kinase, and TGF-ß receptor family genes were almost always truncal. Immune evasion (IE) drivers, such as inactivation of genes involved in antigen presentation or IFN-γ signalling, were predominantly subclonal and showed parallel evolution. These IE drivers have been implicated in immune checkpoint inhibitor resistance or sensitivity. Clonality assessments are therefore important for the development of predictive immunotherapy biomarkers in MMRd CRCs. Phylogenetic analysis identified three distinct patterns of IE driver evolution: pan-tumour evolution, subclonal evolution, and evolutionary stasis. These, but neither mutation burdens nor heterogeneity metrics, significantly correlated with T-cell densities, which were used as a surrogate marker of tumour immunogenicity. Furthermore, this revealed that genetic and T-cell infiltrates coevolve in MMRd CRCs. Low T-cell densities in the subgroup without any known IE drivers may indicate an, as yet unknown, IE mechanism. PD-L1 was expressed in the tumour microenvironment in most samples and correlated with T-cell densities. However, PD-L1 expression in cancer cells was independent of T-cell densities but strongly associated with loss of the intestinal homeobox transcription factor CDX2. This explains infrequent PD-L1 expression by cancer cells and may contribute to a higher recurrence risk of MMRd CRCs with impaired CDX2 expression. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

MicroRNAs as biomarkers for trastuzumab-based therapy in HER2-positive advanced oesophago-gastric cancer patients.

Background: This study aimed to identify microRNAs (miRs) as circulating biomarkers of resistance to first-line trastuzumab-based therapy in advanced HER2-positive oesophago-gastric cancer patients. Methods: A high-throughput 1015 Exiqon miRCURY LNA™ microRNA inhibitor library screen was performed in trastuzumab-treated HER2-positive NCI-N87 and HER2-negative FLO-1 oesophago-gastric cancer cell lines. NanoString nCounter® miR analysis was performed in NCI-N87, FLO-1, and MAGIC trial (ISRCTN93793971) formalin-fixed paraffin-embedded (FFPE) oesophago-gastric cancer patient samples. MiR-148a-3p copies in plasma samples were quantified using digital droplet polymerase chain reaction (ddPCR) from HER2-positive oesophago-gastric cancer patients treated with standard-of-care trastuzumab-based therapy within the FOrMAT (NCT02112357) and PLATFORM (NCT02678182) clinical trials. The primary endpoints were overall survival (OS) for plasma miR-148a-3p HIGH (>median) versus LOW (≤median). The secondary endpoints were progression-free survival (PFS) and 3-month progression-free rates (PFRs) miR-148a-3p HIGH versus LOW. PLATFORM sensitivity analysis normalised miR-148a-3p (NmiR-148a-3p). Results: The inhibition of miR-148a-3p reduced NCI-N87 relative cell viability (<0.6) and expression was high (>242) in NCI-N87 and HER2-positive MAGIC trial patients (n=5). Normalised-miR-148a-3p (NmiR-148a-3p) LOW versus HIGH demonstrated a statistically significant difference in 3-month PFRs (n=23; OR, 0.11 [0.02-0.78]; p=0.027; aOR, 0.03 [0.001-0.71], p=0.029) but no difference in OS or PFS. There was no statistically significant relationship between miR-148-3p LOW versus HIGH for OS (PLATFORM, n=62; hazard ratio [HR], 0.98 [0.57-1.66]; p=0.933; FOrMAT, n=8; HR, 0.54 [0.13-2.31]; p=0.322), PFS (n=62; HR, 1.08 [0.65-1.81]; p=0.759; FOrMAT, n=8; HR, 1.26 [0.31-5.07]; p=0.714), or PFRs (PLATFORM, n=31; odds ratio [OR], 0.67 [0.2-2.8]; p=0.577). Conclusion: Normalised miR-148a-3p may be a relevant biomarker for trastuzumab-based therapy in advanced HER2-positive oesophago-gastric cancer patients.

Targeted Therapies and Developing Precision Medicine in Gastric Cancer.

Gastric cancer is an aggressive disease with survival remaining poor in the advanced setting. More than a decade after the first targeted treatment was approved, still only HER2, MSI and PDL-1 status have reached everyday practice in terms of guiding treatment options for these patients. However, various new targets and novel treatments have recently been investigated and have shown promise in improving survival outcomes. In this review, we will summarise previous and currently ongoing studies on predictive biomarkers, possible new targeted treatments, potential reasons for conflicting trial results and hope for the future of precision medicine in gastric cancer.

Impact of pharmacogenomic DPYD variant guided dosing on toxicity in patients receiving fluoropyrimidines for gastrointestinal cancers in a high-volume tertiary centre.

BACKGROUND: Dihydropyrimidine dehydrogenase (DPD) is a key enzyme in the metabolism of fluoropyrimidines. Variations in the encoding DPYD gene are associated with severe fluoropyrimidine toxicity and up-front dose reductions are recommended. We conducted a retrospective study to evaluate the impact of implementing DPYD variant testing for patients with gastrointestinal cancers in routine clinical practice in a high volume cancer centre in London, United Kingdom. METHODS: Patients receiving fluoropyrimidine chemotherapy for gastrointestinal cancer prior to, and following the implementation of DPYD testing were identified retrospectively. After November 2018, patients were tested for DPYD variants c.1905+1G>A (DPYD*2A), c.2846A>T (DPYD rs67376798), c.1679T>G (DPYD*13), c.1236G>A (DPYD rs56038477), c.1601G>A (DPYD*4) prior to commencing fluoropyrimidines alone or in combination with other cytotoxics and/or radiotherapy. Patients with a DPYD heterozygous variant received an initial dose reduction of 25-50%. Toxicity by CTCAE v4.03 criteria was compared between DPYD heterozygous variant and wild type carriers. RESULTS: Between 1st December 2018 and 31st July 2019, 370 patients who were fluoropyrimidine naïve underwent a DPYD genotyping test prior to receiving a capecitabine (n = 236, 63.8%) or 5FU (n = 134, 36.2%) containing chemotherapy regimen. 33 patients (8.8%) were heterozygous DPYD variant carriers and 337 (91.2%) were wild type. The most prevalent variants were c.1601G > A (n = 16) and c.1236G > A (n = 9). Mean relative dose intensity for the first dose was 54.2% (range 37.5-75%) for DPYD heterozygous carriers and 93.2% (42.9-100%) for DPYD wild type carriers. Overall grade 3 or worse toxicity was similar in DPYD variant carriers (4/33, 12.1%) as compared to wild-type carriers (89/337, 25.7%; P = 0.0924). CONCLUSIONS: Our study demonstrates successful routine DPYD mutation testing prior to the initiation of fluoropyrimidine chemotherapy with high uptake. In patients with DPYD heterozygous variants with pre-emptive dose reductions, high incidence of severe toxicity was not observed. Our data supports routine DPYD genotype testing prior to commencement of fluoropyrimidine chemotherapy.

Neoadjuvant and Adjuvant Therapy Approaches to Gastric Cancer.

OPINION STATEMENT: Gastric cancer is an aggressive malignancy, requiring a multimodality approach to achieve optimal curative rates even when the disease is amenable to surgical resection. Neoadjuvant and adjuvant approaches differ across the globe-a preference for peri-operative chemotherapy exists in Europe, in contrast to the adoption of adjuvant chemotherapy in Asia and adjuvant chemoradiotherapy in North America. There are nuances and limitations associated with each therapeutic strategy and an understanding of these distinct approaches is integral to judicious clinical application of the available data. Although a multimodal approach provides a clear survival benefit above a surgical-only approach, data report low completion rates of adjuvant therapy components and strongly suggest a need to refine patient selection particularly for ongoing treatment in the post-operative period. This may be achieved using a risk-stratified strategy. Hence, there is a need to transition from a generalised approach to a multimodality treatment towards one guided by individual patient clinical features and biomarker profiles in order to improve tolerability and patient outcomes irrespective of geographical variation in clinical practice. While the evidences supporting molecular features such as microsatellite instability and predictive gene signatures are provocative, prospective validation is required before these can be confidently used to direct clinical decision-making.

HER2 Inhibition in Gastric Cancer-Novel Therapeutic Approaches for an Established Target.

Gastric cancer is a leading cause of cancer-related deaths globally. Human epidermal growth receptor 2 (HER2) overexpression of HER2 gene amplification is present in 20% of gastric cancers and defines a subset amenable to HER2-directed therapeutics. The seminal ToGA study led to routine use of the monoclonal antibody trastuzumab in conjunction to platinum-fluoropyridimine first-line chemotherapy for HER2-positive gastric cancers as standard-of-care. Although limited progress was made in the decade following ToGA, there is now an abundance of novel therapeutic approaches undergoing investigation in parallel. Additionally, new data from randomised trials have indicated efficacy of the antibody-drug conjugate trastuzumab deruxtecan in chemorefractory patients and increased responses with the addition of first-line immune checkpoint blockade to trastuzumab and chemotherapy. This review will outline the data supporting HER2 targeting in gastric cancers, discuss mechanisms of response and resistance to HER2-directed therapies and summarise the emerging therapies under clinical evaluation that may evolve the way we manage this subset of gastric cancers in the future.

Activity and toxicity of intramuscular 1000 iu/m2 polyethylene glycol-E. coli L-asparaginase in the UKALL 2003 and UKALL 2011 clinical trials.

In successive UK clinical trials (UKALL 2003, UKALL 2011) for paediatric acute lymphoblastic leukaemia (ALL), polyethylene glycol-conjugated E. coli L-asparaginase (PEG-EcASNase) 1000 iu/m2 was administered intramuscularly with risk-stratified treatment. In induction, patients received two PEG-EcASNase doses, 14 days apart. Post-induction, non-high-risk patients (Regimens A, B) received 1-2 doses in delayed intensification (DI) while high-risk Regimen C patients received 6-10 PEG-EcASNase doses, including two in DI. Trial substudies monitored asparaginase (ASNase) activity, ASNase-related toxicity and ASNase-associated antibodies (total, 1112 patients). Median (interquartile range) trough plasma ASNase activity (14 ± 2 days post dose) following first and second induction doses and first DI dose was respectively 217 iu/l (144-307 iu/l), 265 iu/l (165-401 iu/l) and 292 iu/l (194-386 iu/l); 15% (138/910) samples showed subthreshold ASNase activity (<100 iu/l) at any trough time point. Older age was associated with lower (regression coefficient -9.5; p < 0.0001) and DI time point with higher ASNase activity (regression coefficient 29.9; p < 0.0001). Clinical hypersensitivity was observed in 3.8% (UKALL 2003) and 6% (UKALL 2011) of patients, and in 90% or more in Regimen C. A 7% (10/149) silent inactivation rate was observed in UKALL 2003. PEG-EcASNase schedule in UKALL paediatric trials is associated with low toxicity but wide interpatient variability. Therapeutic drug monitoring potentially permits optimisation through individualised asparaginase dosing.

Harnessing biomarkers of response to improve therapy selection in esophago-gastric adenocarcinoma.

Advanced esophago-gastric (OG) adenocarcinomas have a high mortality rate and new therapeutic options are urgently required. Despite recent advances in understanding the molecular characteristics of OG cancers, tumor heterogeneity poses a challenge in developing new therapeutics capable of improving patient outcomes. Consequently, chemotherapy remains the mainstay of systemic treatment, with the HER2 being the only predictive biomarker routinely targeted in clinical practice. Recent data indicate that immunotherapy will be incorporated into first-line chemotherapy, but further research is required to refine patient selection. This review will summarize the clinical strategies being evaluated to utilize our knowledge of predictive biomarkers with reference to novel therapeutics, and discuss the barriers to implementing precision oncology in OG adenocarcinoma.

Broadening the therapeutic horizon of advanced biliary tract cancer through molecular characterisation.

Biliary tract cancers (BTC) comprise a group of rare and heterogeneous poor-prognosis tumours with the incidence of intrahepatic cholangiocarcinoma increasing over recent years. Combination chemotherapy with gemcitabine and cisplatin is the established first-line treatment for advanced BTC with a significant but modest survival advantage over monotherapy. There remains no accepted standard treatment in the second-line setting, although recent results from a randomised study have shown a survival benefit with 5-fluorouracil and oxaliplatin chemotherapy. Historically, clinical trials investigating targeted therapies in unselected BTC have failed to demonstrate significant clinical benefit. More recently, advancement in molecular exploration of BTC has shed light on the complex biological heterogeneity within these tumours and has also identified actionable genomic aberrations, such as fibroblast growth factor receptor 2 (FGFR2) gene fusions, isocitrate dehydrogenase (IDH) and BRAF mutations, which offer promise with the anticipation of increased responses and durable clinical benefit in selected patients. Several targeted drugs have now entered clinical development with some encouraging results being seen. Here we review the current and rapidly evolving therapeutic landscape of advanced BTC, including targeted therapies and immunotherapy. We also discuss how recent efforts and successes in BTC are overcoming the obstacles typically associated with precision medicine in rare cancers. Ultimately, the management of advanced BTC is likely to become molecularly selected in the near future with the hope of finally improving the bleak prognosis of patients with this disease.

Up-to-Date Tailored Systemic Treatment in Pancreatic Ductal Adenocarcinoma.

Despite intensive research efforts, pancreatic ductal adenocarcinoma is still regarded as an aggressive and life-limiting malignancy. Combination chemotherapy regimens that underpin the current treatment approach in the advanced setting have led to incremental survival gains in recent years but have failed to confer patients with a median overall survival that exceeds 12 months from diagnosis. Research has since focussed on understanding the role and interplay between various components of the desmoplastic stroma and tumour microenvironment, in addition to developing targeted therapies based on molecular features to improve the prognosis associated with this malignancy. This review will summarise the available systemic treatment options and discuss potential methods to refine the resolution of patient selection to enhance responses to currently available therapies. Furthermore, it will explore newer approaches anticipated to come to the fore of future clinical practice, such as agents targeting the DNA damage response and tumour microenvironment as well as immunotherapy-based combinations.