T-cell intrinsic Toll-like receptor signaling: implications for cancer immunotherapy and CAR T-cells

Toll-like receptors (TLRs) are evolutionarily conserved molecules that specifically recognize common microbial patterns, and have a critical role in innate and adaptive immunity. Although TLRs are highly expressed by innate immune cells, particularly antigen-presenting cells, the very first report of a human TLR also described its expression and function within T-cells. Gene knock-out models and adoptive cell transfer studies have since confirmed that TLRs function as important costimulatory and regulatory molecules within T-cells themselves. By acting directly on T-cells, TLR agonists can enhance cytokine production by activated T-cells, increase T-cell sensitivity to T-cell receptor stimulation, promote long-lived T-cell memory, and reduce the suppressive activity of regulatory T-cells. Direct stimulation of T-cell intrinsic TLRs may be a relevant mechanism of action of TLR ligands currently under clinical investigation as cancer immunotherapies. Finally, chimeric antigen receptor (CAR) T-cells afford a new opportunity to specifically exploit T-cell intrinsic TLR function. This can be achieved by expressing TLR signaling domains, or domains from their signaling partner myeloid differentiation primary response 88 (MyD88), within or alongside the CAR. This review summarizes the expression and function of TLRs within T-cells, and explores the relevance of T-cell intrinsic TLR expression to the benefits and risks of TLR-stimulating cancer immunotherapies, including CAR T-cells.

Two successful deliveries of healthy children by a young woman diagnosed and treated during induction and relapsed therapy for acute promyelocytic leukemia

INTRODUCTION

Acute promyelocytic leukemia is an oncologic emergency. The limited cases reported in the literature have led to poor understanding of the safety of management of acute promyelocytic leukemia during pregnancy.

CASE REPORT

Herein is an acute promyelocytic leukemia case of a 22-year-old young pregnant woman who had various social problems. The patient was diagnosed with acute promyelocytic leukemia in her the second trimester of her first pregnancy.Management and outcome: She was treated with all-trans-retinoic acid with idarubicin and successfully delivered a healthy baby. She completed induction with idarubicin but defaulted her all-trans-retinoic acid, 6-mercaptopurine and methotrexate maintenance. She relapsed after one year and was salvaged with all-trans-retinoic acid high dose cytarabine and arsenic trioxide. She went into remission and had autologous stem cells collected and was planned for an autologous stem cell transplant but she defaulted. She relapsed when she was pregnant with her second baby during her third trimester (29+weeks) 10 months later. Salvage chemotherapy with arsenic trioxide, all-trans-retinoic acid and idarubicin was given. Patient underwent an emergency lower segment caesarian section at 31 weeks of pregnancy due to abnormal fetal cardiotocography. A healthy baby was delivered.

DISCUSSION

This drug regimen is controversial during pregnancy owing to the teratogenic effects and fatal retinoic acid syndrome especially in early gestation. In this case, patient was started the induction therapy of all-trans-retinoic acid treatment at her second trimester during her first pregnancy.

CONCLUSION

Our lady demonstrated the possibility of using all-trans-retinoic acid and arsenic trioxide and chemotherapy during second and third trimester with successful pregnancy outcomes.

Spontaneous remission in three cases of AML M5 with NPM1 mutation

Patients with NPM1-mutated AML M5 who develop spontaneous remission (SR) after antibiotic therapy at diagnosis seem to form a favorable prognosis and chemo sensitive subtype. We report three cases of AML M5 patients with the same genotype that experienced transient SR and are now leukemia free after standard treatment.

Cardiopulmonary Failure Requiring ECMO Bypass Resulting from Leukemia Cell Lysis in a Patient with Childhood Acute Myelomonocytic Leukemia

Background. Childhood AML patients are at increased risk for early fatal pulmonary complications. Pulmonary leukostasis and systemic inflammatory response syndrome (SIRS) following leukemia cell lysis are the likely etiologies. Observation. Soon after initiation of AML chemotherapy, an 18-month-old female who met SIRS criteria sustained cardiopulmonary failure requiring ECMO support. Upon recovery, the patient went on to complete therapy and remains in remission without permanent neurologic or cardiac sequelae. Conclusion. Cytokine release syndrome from rapid cell lysis was the likely cause as infectious workup failed to reveal a definitive etiology and drug hypersensitivity testing to the chemotherapy agents was negative.