An immune-related gene expression signature predicts benefit from adding atezolizumab to FOLFOXIRI plus bevacizumab in metastatic colorectal cancer

BACKGROUND

AtezoTRIBE phase II randomized study demonstrated that adding atezolizumab to first-line FOLFOXIRI (5fluoruracil, oxaliplatin, irinotecan) plus bevacizumab prolongs progression-free survival (PFS) of metastatic colorectal cancer (mCRC) patients, with a modest benefit among proficient mismatch repair (pMMR). DetermaIO is an immune-related 27-gene expression signature able to predict benefit from immune-checkpoint inhibition in triple-negative breast cancer. In this analysis of AtezoTRIBE, we investigated the predictive impact of DetermaIO in mCRC.

METHODS

mCRC patients unselected for MMR status were randomized(1:2) to FOLFOXIRI plus bevacizumab (control arm) or the same regimen with atezolizumab (atezolizumab arm). RT-qPCR by DetermaIO was performed on RNA purified from pre-treatment tumours of 132(61%) out of 218 enrolled patients. A binary result (IOpos versus IOneg) adopting the pre-established DetermaIO cut-point (0.09) was obtained, and an exploratory optimized cut-point (IOOPT) was computed in the overall population and in pMMR subgroup (IOOPTpos versus IOOPTneg).

RESULTS

DetermaIO was successfully determined in 122 (92%) cases, and 23 (27%) tumours were IOpos. IOpos tumours achieved higher PFS benefit from atezolizumab arm than IOneg (HR:0.39 versus 0.83, P interaction=0.066). In pMMR tumours (N=110), a similar trend was observed (HR:0.47 versus 0.93, P interaction=0.139). In the overall population, with the computed IOOPT cut-point (0.277), 16 (13%) tumours were IOOPTpos and they derived higher PFS benefit from atezolizumab than IOOPTneg(HR:0.10 versus 0.85, P interaction=0.004). Similar results were found in the pMMR subgroup.

CONCLUSIONS

DetermaIO may be useful to predict benefit of adding atezolizumab to first-line FOLFOXIRI plus bevacizumab in mCRC. The exploratory IOOPT cut-point should be validated in independent mCRC cohorts.

An immune-related gene expression profile to predict the efficacy of adding atezolizumab to first-line FOLFOXIRI plus bevacizumab in metastatic colorectal cancer: A translational analysis of the phase II randomized AtezoTRIBE study

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Background: The phase II randomized AtezoTRIBE study demonstrated that the addition of atezolizumab (atezo) to first-line FOLFOXIRI plus bevacizumab (bev) prolongs PFS of mCRC patients, but benefit is limited among patients with proficient mismatch repair (pMMR) tumours. Among these patients, identifying a subgroup able to achieve benefit from immune-checkpoint inhibitors is a crucial challenge of translational research. To this end, we investigated the potential predictive role of an immunomodulatory gene expression signature (IO score), measuring the presence of infiltrating inflammatory cells and differentiated stromal microenvironment. Methods: AtezoTRIBE was a phase II comparative trial in which mCRC patients, unselected for MMR status, were randomized 1:2 to receive first-line FOLFOXIRI/bev (control arm) or FOLFOXIRI/bev/atezo (experimental arm). RNA was obtained from FFPE blocks of tumour specimens collected at baseline from 142 (65%) out of 218 enrolled patients. RT-qPCR was performed using DetermaIO™, to assess mRNA expression of a targeted panel of 27 genes. The established pan-cancer IO score and threshold were applied to dichotomize tumours as IO-positive (IO+) or IO-negative (IO-). Results: IO score was successfully determined in 122 (86%) cases, and 33 tumours were defined as IO+ (27%). No differences in terms of baseline clinical and molecular features were observed between IO+ and IO- tumours. Patients with IO+ and IO- tumours showed similar PFS (median PFS: 14.4 vs 13.6; HR 0.84 [95%CI: 0.53-1.33], p = 0.468). An interaction between IO status and treatment effect was reported (p for interaction = 0.066), with higher PFS benefit in favour of the experimental arm among patients with IO+ tumours (HR 0.39 [95% CI:0.15-1.02]) than among those with IO- tumours (HR 0.83 [95% CI 0.50-1.35]). A similar trend was observed in the pMMR subgroup (n = 110) (IO+ tumours: HR for PFS 0.47 [95% CI 0.18-1.25]; IO- tumours: HR for PFS 0.93 [95% CI 0.56-1.55]) (p for interaction = 0.139). No differences in terms of ORR were reported between arms according to the IO status. Conclusions: The investigated immunomodulatory signature (IO score) may be helpful to predict benefit from the addition of atezolizumab to first-line FOLFOXIRI/bev in metastatic colorectal cancer, also in the cohort of pMMR tumours. Our results support the hypothesis that a deeper characterization of tumour immune microenvironment may help identifying mCRC patients more likely to benefit from ICI-based therapeutic strategies. These findings are worthy of further investigation in independent cohorts.

The 27-gene IO score is associated with molecular features and response to immune checkpoint inhibitors (ICI) in patients with gastric cancer

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Background: Gastric cancer (GC) is the 3rd leading cause of cancer-related death worldwide. Unfortunately, most gastric cancer patients are asymptomatic until the cancer has progressed to an advanced stage. ICIs have improved patient outcomes in a variety of cancers, including GC. A variety of biomarkers have been used to identify patients most likely to benefit from ICI therapies such as high PD-L1 expression, MSI-high, Epstein Barr virus (EBV) positive, or TMB. Despite these potential biomarkers, most patients with advanced GC do not respond to ICI treatment Thus, there remains an unmet clinical need for a biomarker that can better predict response to ICI therapies. Herein, we demonstrate that the 27 gene IO score, a tumor immune microenvironment (TIME) classifier is associated with the existing molecular markers of gastric cancer and with objective response to ICI therapy in a clinical cohort. Methods: RNA-seq expression data was obtained from 3 independent cohorts including TCGA (STAD), ACRG (GSE84437, GSE84426), and clinical cohort with ICI response data (PRJEB25780, PRJEB40416). The 27 gene IO algorithm was applied to all available patient data to derive IO scores. Fisher’s exact test was used to examine the associations between IO score and clinical features and molecular subtypes in each cohort. R (version 4.1.2) was used to calculate ORs with 95%CIs, and ordinal logistic regression modeling. Results: From the TCGA cohort, the IO score was associated with the molecular features of EBV, MSI, TMB, and PD-L1 (n = 135, p < 0.05 for all). Similarly, in the ACRG cohorts, the IO score was significantly associated with EBV, MSI, and PD-L1 ( n = 294, p < 0.001 for all). To determine whether the IO score was associated with response to ICIs, we examined a cohort of Korean patients with advanced stage GC curated by Kim et. al. In this cohort of 59 patients, the IO score was associated with ICI response (Fisher’s exact test, p < 0.05). When response was grouped by responders vs. non-responders (CR/PR vs SD/PD), the odds ratio for the association between IO score and response was 5.3 (95% CI: 1.3 to 23.92, p = 0.01). The linearity of continuous value of the IO score was indicative of a direct relationship between IO score and improved objective response (ordinal logistic regression, t = 2.59, p < 0.01). Conclusions: PD-L1 and TMB have shown marked levels of both spatial and temporal heterogeneity in GCs, thus there exists a need for a more comprehensive biomarker that can fully assess the TIME. The 27 gene IO score is associated with many existing biomarkers in GC and has now been shown to also be associated with response to ICIs. As such, further studies are warranted to demonstrate that the 27 gene IO score may be a more comprehensive biomarker for assessing the TIME and provide complementary data to tumor-specific biomarkers, which together could aid in clinical decision making for ICI treatment of GCs.

Serum antibodies to selected Helicobacter pylori antigens are associated with active gastritis in patients seen at the University Teaching Hospital in Lusaka, Zambia

IntroductionLittle is known about specific bacterial characteristics of Helicobacter pylori (H. pylori) infection influencing gastric carcinogenesis in Zambia. The aim of this study was to evaluate the associations between pre-selected H. pylori antibodies with gastric cancer, premalignant lesions and active gastritis. MethodsThis was cross-sectional study with multiple comparisons of patients with gastric cancer (GC), gastric premalignant (GP) lesions and active or chronic gastritis. A fluorescent bead-based antibody multiplex serology assay was used to quantify antibodies to thirteen immunogenic H. pylori antigens. Logistic regression models were used to examine the associations.ResultsIncluded were 295 patients with: 59 GC, 27 GP lesions, 48 active and 161 chronic gastritis. Overall, 257/295 (87%) were H. pylori positive. H. pylori seropositivity was not associated with sex, age, body mass index, socio-economic status, HIV infection, alcohol consumption or cigarette smoking (p-values all above 0.05). When compared to the patients with chronic gastritis, the presence of catalase and cinnamyl alcohol dehydrogenase (Cad) antibodies was positively associated with GP lesions (OR 3.53; 95% CI 1.52-8.17 and OR 2.47; 95% CI 1.08-5.67 respectively). However, seropositivity to Cad antibodies was significantly lower in GC patients (OR 0.28; 95% CI 0.09-0.83). Compared to chronic, active gastritis was significantly associated with (p<0.05) H. pylori sero-positivity (OR 9.46; 95% CI 1.25-71.52) and specific antibodies including cytotoxin-associated gene A, vacuolating cytotoxin A, Helicobacter cysteine-rich protein C, hypothetical protein HP0305 and outer membrane protein HP1564. ConclusionsAmong Zambian patients seen at a single center, antibodies to H. pylori (CagA, VacA, Omp, HcpC, HP0305 and HpaA) were associated with active gastritis.

Pathogenic Helicobacter pylori strains translocate DNA and activate TLR9 via the cancer-associated cag type IV secretion system

Helicobacter pylori is the strongest identified risk factor for gastric cancer, the third most common cause of cancer-related death worldwide. An H. pylori constituent that augments cancer risk is the strain-specific cag pathogenicity island, which encodes a type IV secretion system (T4SS) that translocates a pro-inflammatory and oncogenic protein, CagA, into epithelial cells. However, the majority of persons colonized with CagA⁺H. pylori strains do not develop cancer, suggesting that other microbial effectors also play a role in carcinogenesis. Toll-like receptor 9 (TLR9) is an endosome bound, innate immune receptor that detects and responds to hypo-methylated CpG DNA motifs that are most commonly found in microbial genomes. High expression tlr9 polymorphisms have been linked to the development of premalignant lesions in the stomach. We now demonstrate that levels of H. pylori-mediated TLR9 activation and expression are directly related to gastric cancer risk in human populations. Mechanistically, we show for the first time that the H. pylori cancer-associated cag T4SS is required for TLR9 activation and that H. pylori DNA is actively translocated by the cag T4SS to engage this host receptor. Activation of TLR9 occurs through a contact-dependent mechanism between pathogen and host, and involves transfer of microbial DNA that is both protected as well as exposed during transport. These results indicate that TLR9 activation via the cag island may modify the risk for malignancy within the context of H. pylori infection and provide an important framework for future studies investigating the microbial-epithelial interface in gastric carcinogenesis.