Ibrutinib directly reduces CD8+T cell exhaustion independent of BTK

Leveraging the Immunomodulatory Potential of Ibrutinib for Improved Outcomes of T Cell-Mediated Therapies of B Cell Malignancies: A Narrative Review

Standard treatment options for B cell malignancies include immunochemotherapies and/or targeted therapies, which often provide temporary disease remission. However, many patients do not achieve complete remission with these treatments, develop resistance, and eventually experience disease relapse. New immunomodulatory treatments, such as T cell-based therapies, show promise in treating various types of blood cancers, including B cell malignancies. However, their effectiveness is often limited by the immunosuppressive tumor microenvironment and altered function of patient-derived T cells. Ibrutinib, a Bruton tyrosine kinase inhibitor, has been shown to restore immune balance and function in patients with chronic lymphocytic leukemia. Ibrutinib is being studied as adjuvant or combinatorial therapy with chimeric antigen receptor (CAR) T cells or T cell-engaging bispecific antibodies for the treatment of B cell malignancies. Current evidence suggests that ibrutinib could be beneficial when used before, during, or after CAR T cell administration, potentially providing higher complete response rates and reduced toxicity. In conclusion, existing evidence strongly supports the combined use of ibrutinib and T cell therapies. However, additional clinical trials are needed to further validate the effectiveness of this treatment strategy in patients with various B cell malignancies.

U-Type-Shaped Curves Across Economics, Biology, and Infection

Major threats to the economic future of several nations include climate change, infectious pandemics, and drug-resistant bacteria. The rise and fall of each of these behaviors seems to conform to a U-shaped or inverted U-shaped curve. In academic medicine, stakeholders in the field (infection control personnel, epidemiologists, and vaccinologists) will argue that infectious outbreaks can be prevented by surveillance programs and the development of new drugs (antibiotics, vaccines, etc.). The promise of vaccines, antibiotics, genetic manipulations, air filtration, agriculture control measures, etc., is that with next-generation technology, effective countermeasures can be rapidly deployed to combat any emerging threat to our ecosystem and hence our economy. In this piece, we advance the idea that Laffer curves and their U-type-shaped ancestors share interconnectedness across multiple domains of science including biology, economics, infectious disease, and ecology. U-type-shaped curves and their sibling, the inverted U-curve, conform to the general principle of hormesis, a biphasic response where there is a measured benefit at lower exposures to a phenomenon yet harm when exposure is excessive (i.e., low-dose stimulation and high-dose inhibition).

IL-2-inducible T cell kinase deficiency sustains chimeric antigen receptor T cell therapy against tumor cells

Despite the revolutionary achievements of chimeric antigen receptor (CAR) T cell therapy in treating cancers, especially leukemia, several key challenges still limit its therapeutic efficacy. Of particular relevance is the relapse of cancer in large part as a result of exhaustion and short persistence of CAR-T cells in vivo. IL-2-inducible T cell kinase (ITK) is a critical modulator of the strength of T cell receptor signaling, while its role in CAR signaling is unknown. By electroporation of CRISPR-associated protein 9 (Cas9) ribonucleoprotein (RNP) complex into CAR-T cells, we successfully deleted ITK in CD19-CAR-T cells with high efficiency. Bulk and single-cell RNA sequencing analyses revealed downregulation of exhaustion and upregulation of memory gene signatures in ITK-deficient CD19-CAR-T cells. Our results further demonstrated a significant reduction of T cell exhaustion and enhancement of T cell memory, with significant improvement of CAR-T cell expansion and persistence both in vitro and in vivo. Moreover, ITK-deficient CD19-CAR-T cells showed better control of tumor relapse. Our work provides a promising strategy of targeting ITK to develop sustainable CAR-T cell products for clinical use.

Small molecule inhibitors as adjuvants in cancer immunotherapy: enhancing efficacy and overcoming resistance

Adjuvant therapy is essential in cancer treatment to enhance primary treatment effectiveness, reduce adverse effects, and prevent recurrence. Small molecule inhibitors as adjuvants in cancer immunotherapy aim to harness their immunomodulatory properties to optimize treatment outcomes. By modulating the tumor microenvironment, enhancing immune cell function, and increasing tumor sensitivity to immunotherapy, small molecule inhibitors have the potential to improve patient responses. This review discusses the evolving use of small molecule inhibitors as adjuvants in cancer treatment, highlighting their role in enhancing the efficacy of immunotherapy and the opportunities for advancing cancer therapies in the future.

Ibrutinib disrupts blood-tumor barrier integrity and prolongs survival in rodent glioma model

In malignant glioma, cytotoxic drugs are often inhibited from accessing the tumor site due to the blood-tumor barrier (BTB). Ibrutinib, FDA-approved lymphoma agent, inhibits Bruton tyrosine kinase (BTK) and has previously been shown to independently impair aortic endothelial adhesion and increase rodent glioma model survival in combination with cytotoxic therapy. Yet additional research is required to understand ibrutinib's effect on BTB function. In this study, we detail baseline BTK expression in glioma cells and its surrounding vasculature, then measure endothelial junctional expression/function changes with varied ibrutinib doses in vitro. Rat glioma cells and rodent glioma models were treated with ibrutinib alone (1-10 µM and 25 mg/kg) and in combination with doxil (10-100 µM and 3 mg/kg) to assess additive effects on viability, drug concentrations, tumor volume, endothelial junctional expression and survival. We found that ibrutinib, in a dose-dependent manner, decreased brain endothelial cell-cell adhesion over 24 h, without affecting endothelial cell viability (p < 0.005). Expression of tight junction gene and protein expression was decreased maximally 4 h after administration, along with inhibition of efflux transporter, ABCB1, activity. We demonstrated an additive effect of ibrutinib with doxil on rat glioma cells, as seen by a significant reduction in cell viability (p < 0.001) and increased CNS doxil concentration in the brain (56 ng/mL doxil alone vs. 74.6 ng/mL combination, p < 0.05). Finally, Ibrutinib, combined with doxil, prolonged median survival in rodent glioma models (27 vs. 16 days, p < 0.0001) with brain imaging showing a - 53% versus - 75% volume change with doxil alone versus combination therapy (p < 0.05). These findings indicate ibrutinib's ability to increase brain endothelial permeability via junctional disruption and efflux inhibition, to increase BTB drug entry and prolong rodent glioma model survival. Our results motivate the need to identify other BTB modifiers, all with the intent of improving survival and reducing systemic toxicities.