Managing Resistance to Immune Checkpoint Inhibitors in Lung Cancer: Treatment and Novel Strategies

A proportion of patients with lung cancer experience long-term clinical benefit with immune checkpoint inhibitors (ICIs). However, most patients develop disease progression during treatment or after treatment discontinuation. Definitions of immune resistance are heterogeneous according to different clinical and biologic features. Primary resistance and acquired resistance, related to tumor-intrinsic and tumor-extrinsic mechanisms, are identified according to previous response patterns and timing of occurrence. The clinical resistance patterns determine differential clinical approaches. To date, several combination therapies are under development to delay or prevent the occurrence of resistance to ICIs, including the blockade of immune coinhibitory signals, the activation of those with costimulatory functions, the modulation of the tumor microenvironment, and the targeting T-cell priming. Tailoring the specific treatments with distinctive biologic resistance mechanisms would be ideal to improve the design and results of clinical trial. In this review, we reviewed the available evidence on immune resistance mechanisms, clinical definitions, and management of resistance to ICIs in lung cancer. We also reviewed data on novel strategies under investigation in this setting.

Regulation of B Cell Receptor Signaling and Its Therapeutic Relevance in Aggressive B-Cell Lymphomas

The proliferation and survival signals emanating from the B-cell receptor (BCR) constitute a crucial aspect of mature lymphocyte’s life. Dysregulated BCR signaling is considered a potent contributor to tumor survival in different subtypes of B cell non-Hodgkin lymphomas (B-NHLs). In the last decade, emergence of BCR-associated kinases as rational therapeutic targets has led to the development and approval of several small molecule inhibitors targeting either Bruton's tyrosine kinase (BTK), spleen tyrosine kinase (SYK), or phosphatidylinositol 3 kinase (PI3K), offering alternative treatment options to standard chemoimmunotherapy, and making some of these drugs valuable assets in the anti-lymphoma armamentarium. Despite their initial effectiveness, these precision medicine strategies are limited by primary resistance in aggressive B-cell lymphoma like diffuse large B cell lymphoma (DLBCL) and mantle cell lymphoma (MCL), especially in the case of first generation BTK inhibitors. In these patients, BCR-targeting drugs often fail to produce durable responses, and nearly all cases eventually progress with a dismal outcome, due to secondary resistance. This review will discuss our current understanding of the role of antigen-dependent and antigen-independent BCR signaling in DLBCL and MCL and will cover both approved inhibitors and investigational molecules being evaluated in early preclinical studies. We will discuss how the mechanisms of action of these molecules, and their off/on-target effects can influence their effectiveness and lead to toxicity, and how our actual knowledge supports the development of more specific inhibitors and new, rationally based, combination therapies, for the management of MCL and DLBCL patients.

Accelerated Methods of Determining Wheat Genotypes Primary Resistance to Extreme Temperatures

Several morphological and functional mechanisms determine the resistance of plants to extreme temperatures. Depending on the specificity of mechanisms of action, we divided them into two groups: (1) the mechanisms that ensure the avoidance/reduction of the exposure dose; (2) functional mechanisms which increase plant resistance and ability to recover damages caused by stress through regulation metabolic and genes expression activity. We developed theoretical and practical methods to appreciate the contribution of parameters from both groups on the primary and adaptive resistance of different wheat genotypes. This problem became more complicated because some properties are epigenetically inherited and can influence genotypes’ primary (initial) resistance to stressors. The article describes results obtained by the accelerated determination of the initial resistance of wheat (Triticum aestivum L.) genotypes to temperature stress and the prospects for their implementation in the selection and development of methods for rational choosing wheat varieties for cultivation under specific environmental conditions.

Association between Immune-Related Adverse Events and Survival in 319 Stage IV Melanoma Patients Treated with PD-1-Based Immunotherapy: An Approach Based on Clinical Chemistry

(1) Background: Immune checkpoint inhibitors have improved the prognosis of patients with advanced melanoma. Published data suggested that the objective response rates appear to be superior in patients who developed immune-related adverse events (irAEs). (2) The primary aim of this cohort study was to evaluate the association between irAEs and disease control rate in patients with stage IV melanoma treated with first-line PD-1-based immunotherapy. (3) Among 319 patients, 53% experienced at least one irAE. A higher percentage of patients with irAEs had disease control compared to those without irAEs (69.8% vs. 49.3%). In multivariate analysis, development of grade 3 and 4 irAEs was significantly associated with a protective effect for the outcome primary resistance (OR: 0.40 95% CI 0.23–0.70, p = 0.001). The presence of any grade irAEs was significantly associated with longer OS (irAEs grade 1–2 HRadj: 0.61 95% CI: 0.4–0.93, p = 0.02, irAEs grade 3–4 HRadj: 0.55 95% CI 0.31–0.99, p = 0.04), but not with PFS (irAEs grade 1–2 HRadj: 1.21 95% CI: 0.91–1.79, p = 0.16, irAEs grade 3–4 HRadj: 1.14 95% CI 0.83–2.02, p = 0.24). (4) The presence of irAEs with laboratorial expression is positively associated with response and OS, suggesting that irAEs might be a predictive factor in this setting.

Emergence of Amoxicillin Resistance and Identification of Novel Mutations of the pbp1A Gene in Helicobacter pylori in Vietnam

Background Amoxicillin resistant Helicobacter pylori (H. pylori) strains seem to have increased over time in Vietnam. This threatens the effectiveness of H. pylori eradication therapies with this antibiotic. This study aimed to investigate the prevalence of primary resistance of H. pylori to amoxicillin and to assess its association with pbp1A point mutations in Vietnamese patients. Materials and Methods Naive patients who presented with dyspepsia undergoing upper gastrointestinal endoscopy were recruited. Rapid urease tests and PCR assays were used to diagnose H. pylori infection. Amoxicillin susceptibility was examined by E-tests. Molecular detection of the mutant pbp1A gene conferring amoxicillin resistance was carried out by real-time PCR followed by direct sequencing of the PCR products. Phylogenetic analyses were performed using the Tamura-Nei genetic distance model and the neighbour-joining tree building method. Results There were 308 patients (46.1% men and 53.9% women, p = 0.190) with H. pylori infection. The mean age of the patients was 40.5 ± 11.4 years, ranging from 18 to 74 years old. The E-test was used to determine the susceptibility to amoxicillin (minimum inhibitory concentration (MIC) ≤ 0.125 µg/ml) in 101 isolates, among which the rate of primarily resistant strains to amoxicillin was 25.7%. Then, 270 sequences of pbp1A gene fragments were analysed. There were 77 amino acid substitution positions investigated, spanning amino acids 310–596, with the proportion varying from 0.4–100%. Seven amino acid changes were significantly different between amoxicillin-sensitive (AmoxS) and amoxicillin-resistant (AmoxR) samples, including Phe366 to Leu (p < 0.001), Ser414 to Arg (p < 0.001), Glu/Asn464−465 (p = 0.009), Val469 to Met (p = 0.021), Phe473 to Val (p < 0.001), Asp479 to Glu (p = 0.044), and Ser/Ala/Gly595−596 (p = 0.001). Phylogenetic analyses suggested that other molecular mechanisms might contribute to amoxicillin resistance in H. pylori in addition to the alterations in PBP1A. Conclusions We reported the emergence of amoxicillin-resistant Helicobacter pylori strains in Vietnam and new mutations statistically associated with this antimicrobial resistance. Additional studies are necessary to identify the mechanisms contributing to this resistance in Vietnam.

An Early-Onset Advanced Rectal Cancer Patient With Increased KRAS Gene Copy Number Showed A Primary Resistance to Cetuximab in Combination With Chemotherapy: A Case Report

Mutations in KRAS (codon 12/13), NRAS, BRAFV600E, and amplification of ERBB2 and MET account for 70–80% of anti-epidermal growth factor receptor (EGFR) monoclonal antibody primary resistance. However, the list of anti-EGFR monoclonal antibody primary resistance biomarkers is still incomplete. Herein, we report a case of wild-type RAS/BRAF metastatic colorectal cancer (CRC) with resistance to anti-EGFR monoclonal antibody and chemotherapy. Initially, mutation detection in postoperative tumor tissue by using amplification-refractory mutation system polymerase chain reaction indicated wild-type RAS/BRAF without point mutations, insertion deletions, or fusion mutations. Therefore, we recommended combined therapy of cetuximab and FOLFIRI after failure of platinum-based adjuvant chemotherapy, but the disease continued to progress. Next generation sequencing analysis of the postoperative tumor tissue revealed that KRAS copy number was increased and detected SMAD4, RNF43, and PREX2 mutations. This is the first case of advanced CRC with increased copy numbers of KRAS resistant to cetuximab and chemotherapy, which results in poor patient survival, and other mutated genes may be associated with the outcomes. Our findings indicate KRAS copy number alterations should also be examined, especially with anti-EGFR monoclonal antibody therapy in CRC, since it may be related with the primary resistance to these drugs.

Single-Cell Multi-Omic Analysis Uncovers Comprised Immune Function and Primary Resistance Mechanism in Acute Myeloid Leukemia

Background: Approximately 20% of AML patients do not respond to induction chemotherapy (primary resistance) and 40-60% of patients develop secondary resistance, eventually leading to relapse followed by refractory disease (RR-AML). Diversified molecular mechanisms have been proposed for drug resistance and RR phenotype. However, we still cannot predict when relapse will occur, nor which patients will become resistant to therapy. Single-cell multi-omic (ScMo) profiling may provide new insights into our understanding of hematopoietic stem cell (HSC) differentiation trajectories, tumor heterogeneity and clonal evolution. Here we applied ScMo to profile bone marrow (BM) from AML patients and healthy controls. Methods: AML samples were collected at diagnosis with institutional IRB approval. Cells were stained with a panel of 62 DNA barcoded antibodies and 10x Genomics Single Cell 3' Library Kit v3 was used to generate ScMo data. After normalization, clusters were identified using Uniform Manifold Approximation and Projection (UMAP) and annotated using MapCell (Koh and Hoon, 2019). We analyzed 23,933 cells from 4 adult AML BM samples, and 39,522 cells from 2 healthy adults and 3 sorted CD34+ normal BM samples. Gene set enrichment analysis (GSEA) and Enrichr program were used to examine underlying pathways among differentially expressed genes between healthy and AML samples. Results: We identified 16 cell types between the AML and normal samples (Fig 1a) amongst 45 clusters in the UMAP projection (Fig 1b). Comparative analysis of the T cell clusters in AML samples with healthy BM cells identified an "AML T-cell signature" with over-expression of genes such as granzymes, NK/T cell markers, chemokine and cytokine, proteinase and proteinase inhibitor (Fig 2a). Among them, IL32 is known to be involved in activation-induced cell death in T cells and has immunosuppressive role, while CD8+ GZMB+ and CD8+ GZMK+ cells are considered as dysfunctional or pre-dysfunctional T cells. Indeed, Enrichr analysis showed the top rank of phenotype term - "decreased cytotoxic T cell cytolysis". We next examined whether NK cells, are similarly dysfunctional in the AML ecosystem. The "AML NK cell signature" includes Fc Fragment family, IFN-stimulated genes (ISGs), the effector protein-encoding genes and other genes when compared to normal NK cells (Fig 2b). GSEA analysis revealed "PD-1 signalling" among the top 5 ranked pathways in AML-NK cells, though no increase in PD-1 protein nor PDCD1 gene were identified in these cells. Inhibitory receptor CD160 was expressed higher in AML samples along with exhaustion (dysfunction) associated genes TIGIT, PRF1 and GZMB (Fig 2c). Enrichr analysis uncovered enrichment of "abnormal NK cell physiology and "impaired natural killer cell mediated cytotoxicity". Similarly, the "AML monocyte signature" was significantly enriched with genes in "Tumor Infiltrating Macrophages in Cancer Progression and Immune Escape" and "Myeloid Derived Suppressor Cells in Cancer Immune Escape". We also analyzed HSPC component in one pair of cytogenetically matched, untreated complete remission (CR) /RR AML pair (Fig 2d). Notably, half of the 10 genes overexpressed in RR-AML, CXCR4, LGALS1, S100A8, S100A9, SRGN (Serglycin), regulate cell-matrix interaction and play pivotal roles in leukemic cells homing bone marrow niche. The first 4 of these genes have been demonstrated as prognostic indicators of poor survival and associated with chemo-resistance and anti-apoptotic function. Furthermore, single-cell trajectory analysis of this CR/RR pair illustrated a change in differentiation pattern of HSPCs in CR-AML to monocytes in RR-AML. We are currently analyzing more AML samples to validate these findings. Conclusions: Our ScMo analysis demonstrates that the immune cells are systematically reprogrammed and functionally comprised in the AML ecosystem. Upregulation of BM niche factors could be the underlying mechanism for RR-AML. Thus, reversing the inhibited immune system is an important strategy for AML therapy and targeting leukemic cell-BM niche interaction should be considered for cases with high expression of these molecules on AML HSPCs. Note: J.Z. and J.A.S. share co-first authorship. Figure 1 Figure 1. Disclosures Scolnick: Proteona Pte Ltd: Current holder of individual stocks in a privately-held company. Xu: Proteona Pte Ltd: Current Employment. Ooi: Jansen: Honoraria; Teva Pharmaceuticals: Honoraria; GSK: Honoraria; Abbvie: Honoraria; Amgen: Honoraria. Lovci: Proteona Pte Ltd: Current Employment. Chng: Aslan: Research Funding; Takeda: Honoraria; Johnson & Johnson: Honoraria, Research Funding; BMS/Celgene: Honoraria, Research Funding; Amgen: Honoraria; Novartis: Honoraria, Research Funding; Antengene: Honoraria; Pfizer: Honoraria; Sanofi: Honoraria; AbbVie: Honoraria.

Priming Death Receptor Mediated Apoptosis with Arginine Starvation Sensitises Arginine Auxotrophic B-ALL to CAR-T

Background Chimeric antigen receptor (CAR)-T cell therapy has revolutionised the treatment of relapsed or refractory B-ALL in children and young adults with unprecedented response rates. However, primary resistance and relapse are unresolved challenges that limit long term benefit in a significant proportion of patients. Death receptor mediated extrinsic apoptosis is a key component of CAR-T cytotoxicity and impairment of this system, of which CAR-T derived TRAIL (tumour necrosis factor related apoptosis inducing ligand) is a key initiator, is a principal driver of primary resistance. Arginine deprivation with the therapeutic enzyme ADI-PEG20 (pegylated arginine deiminase) sensitises cancers deficient in the enzyme argininosuccinate synthase (ASS1) to the apoptosis initiating activity of TRAIL through tumour cell surface upregulation of death receptors DR4 and DR5. Whether this effect could potentiate the TRAIL-DR activity in CAR-T therapy has not been explored. Aim We tested the hypothesis that ADI-PEG20 treatment can sensitise susceptible B-ALL to anti-CD19 CAR-T through priming of death receptor mediated apoptosis signalling. Methods The effect of ADI-PEG20 on cell survival and death receptor expression in B-ALL cell lines and primary samples was analysed by flow cytometry. Second generation anti-CD19 CAR-T cells with a CD28 costimulatory domain were generated by retroviral transduction of activated peripheral blood mononuclear cells (PBMC) from healthy donors. For CAR-T co-culture experiments, B-ALL cell lines were pre-treated with ADI-PEG20 before washing and re-suspending in arginine replete media prior to CAR-T cell addition. Results To establish potential susceptibility of B-ALL to ADI-PEG20 we measured expression of ASS1, which inversely correlates with sensitivity to the drug, using combined in situ immunohistochemistry (n=6) and RT-qPCR (n=7). ASS1 deficiency was consistently seen in this series of primary samples suggesting the potential utility of ADI-PEG20 in B-ALL, with comparable expression levels to those seen in a cohort of primary AML samples proven to be sensitive to the drug (figure 1a). Next, to examine variation in ASS1 expression between genetically defined subtypes of B-ALL we re-analysed transcriptome data from a cohort of 215 patients treated on the ECOG E2993 trial, filtered into a network of 58 genes generated according to known or predicted interaction with ASS1. We found an enrichment of Philadelphia chromosome positive (Ph+) and Philadelphia-like (Ph-L) samples in the cluster characterised by lowest ASS1 expression along with high HIF1A expression, matching a recurrent pattern reported in other ADI-PEG20 sensitive tumours. This therefore predicts that among B-ALL subtypes, Ph+ and Ph-L are likely to be most sensitive to therapeutic arginine deprivation. We then functionally confirmed, using in vitro cell line (n=3) and in vivo patient derived xenograft models of B-ALL (n=2), that ASS1 deficiency is required for ADI-PEG20 sensitivity. Using the ASS1-low, Ph-L cell line MUTZ-5, we established that ADI-PEG20 induced apoptosis accompanies cell surface upregulation of both DR4 and DR5 expression. Upregulation of DR4 was observed to follow an upwards trend after treated cells were washed and re-suspended in arginine replete media, suggesting that transient arginine starvation can commit ASS1-low B-ALL to a state of apoptotic priming (figure 1b). With confirmed engagement of arginine starvation and death receptor upregulation we tested the synergy potential of ADI-PEG20 pre-treatment of MUTZ-5 followed by CAR-T, utilising calculated combination drug indices (CDIs). Across independent PBMC donors (n=3) we observed greater potency killing of CD19 + leukaemia cells in the combination treated co-cultures when compared to the single agent treated conditions, with CDIs consistently less than 1 confirming a synergistic effect (figure 1c). Conclusion Our study proposes a synergistic interaction between the arginine depleting enzyme ADI-PEG20 and anti-CD19 CAR-T for the treatment of ASS1 deficient B-ALL, whereby priming of death receptor signalling may underlie enhanced CAR-T cytotoxicity against CD19 + tumour cells. These data support an emerging framework for CAR-T optimisation based on targeting of the death receptor mediated extrinsic apoptosis pathway and can inform future refinements in the development of cellular immunotherapy. Figure 1 Figure 1. Disclosures Bomalaski: Polaris Pharmaceuticals Inc.: Current Employment. Maher: Leucid Bio: Other: Chief Scientific Officer. Gribben: Abbvie: Honoraria; AZ: Honoraria, Research Funding; BMS: Honoraria; Gilead/Kite: Honoraria; Janssen: Honoraria, Research Funding; Morphosys: Honoraria; Novartis: Honoraria; Takeda: Honoraria; TG Therapeutis: Honoraria.

Analysis of Early Events during the First Year of Tyrosine Kinase Inhibitor Therapy in Patients with Chronic Phase - Chronic Myeloid Leukemia: A "Campus CML" Study

Background Tyrosine kinase inhibitors (TKIs) revolutionized treatment of chronic myeloid leukemia (CML). However, the first months of therapy are crucial, as optimal response is defined as the achievement of molecular milestones at 3, 6 and 12 months (mo.) and as many toxicities, also causing a TKI switch, are more frequent in the 1st year. Methods To evaluate achievement of early molecular response (MR) and incidence of events leading to a TKI change during the 1st year of therapy, we retrospectively studied 1650 CP-CML patients diagnosed from 2012 and 2019 at 31 Hematology Centres and treated with frontline imatinib (IM) or second-generation (2G) TKIs dasatinib or nilotinib. Optimal MR at 3, 6 and 12 mo. were assessed according to 2020 ELN recommendations. Results Frontline TKI was IM in 926 (56.1%) and 2G-TKIs in 724 (43.9%) cases: the main clinical features at diagnosis of the entire cohort and according to frontline treatment is reported in the Table 1. Commonest comorbidities were arterial hypertension (38.7%), previous neoplasm (13.6%), diabetes (11.3%), peripheral vascular diseases (7.8%), COPD (7.5%) and ischemic heart disease (6.8%). IM-treated patients were older (p&lt;0.001), with higher ELTS score (int/high 47.6% vs 35.6%, p&lt;0.001) and more comorbidities (p&lt;0.005 for all diseases). Optimal MR was achieved at 3 mo. by 1186/1430 (82.9%), at 6 mo. by 1025/1352 (75.8%) and at 12 mo. by 826/1264 patients (65.3%), respectively. Total number of patients discontinuing TKI in the 1st year was 321/1650 (19.4%), being higher with IM (237/926, 25.5%) than 2G-TKIs (84/724, 11.6%) (p&lt;0.001). Main causes were primary resistance (8.7%, 12.3% IM vs 4.2% 2G-TKIs, p&lt;0.001), extra-hematologic toxicity (6.4%, 8.2% IM vs 4.2% 2G-TKIs, p&gt;0.001), hematologic toxicity (1.7%, 2.0% IM vs 1.4% 2G-TKIs, p=0.25) and progression (1.0%, 1.2% IM vs 0.8% 2G-TKIs, p=0.56). Cumulative incidence of discontinuation at 3, 6 and 12 mo. were 5.6%, 10.7% and 19.3%, respectively; values for IM and 2G-TKIs at the three timepoints were 8.1%, 15.0%, 25.5% and 2.5%, 5.3%, 11.5% (p&lt;0.001) (Fig. 1). Conclusions This real-world study on over 1600 CML patients shows that almost 20% discontinue frontline TKI during the 1st year, mostly for primary resistance or toxicity. Discontinuation rates are higher with IM compared to 2G-TKIs, mostly at 3 mo. and are probably due to a lower attainment of early MR. The impact of older age, higher risks and heavier burden of comorbidities in IM patients should be considered and need deeper investigation. Figure 1 Figure 1. Disclosures Elena: GILEAD: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; PFIZER: Membership on an entity's Board of Directors or advisory committees; CELGENE: Other: funding for meeting participation. Sportoletti: AstraZeneca: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria. Stagno: InCyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Other: Support for attending meetings and/or travel; Novartis: Consultancy, Honoraria, Other: Support for attending meetings and/or travel, Research Funding. Iurlo: Pfizer: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Bonifacio: Novartis: Honoraria; Pfizer: Honoraria; Amgen: Honoraria; Bristol Myers Squibb: Honoraria. Breccia: Pfizer: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Bristol Myers Squibb/Celgene: Honoraria; Novartis: Honoraria. Latagliata: Novartis: Honoraria; Pfizer: Honoraria; BMS Cellgene: Honoraria.