Radiation Therapy Sensitizes Head-and-Neck Cancer Cells to Killing by Chimeric Antigen Receptor (CAR)-NK Cells Targeting CD70

PURPOSE/OBJECTIVE(S)

CAR-T cell therapy is limited by toxicity, high cost, logistical manufacturing issues in the autologous setting and risk of GVHD in the allogeneic setting. Substitution of T cells with NK cells opens the possibility for an allogeneic off-the-shelf product with a better safety profile. However, the inadequate efficacy of CAR-NK cells against solid tumors can be extrapolated from experience with CAR-T cells. There is limited but promising preclinical evidence that radiation therapy (RT) enhances CAR-T cell tumoricidal activity against solid tumors. However, there is no data examining the potential synergy between RT and CAR-NK cell therapy.

MATERIALS/METHODS

We engineered CAR-NK cells with CD27 receptor as extracellular domain to target its natural ligand CD70, which is overexpressed in head-and-neck cancers (HNSCC). CAR-NK cell killing was assessed real-time through xCELLigence cytotoxicity assays. CD70+ OQ01 human HNSCCs were used for most experiments. FaDu is a CD70- HNSCC (negative ctrl). UMRC3 is a CD70+ kidney cancer cell line (positive ctrl). CD70 expression pre- and post-RT was assessed by flow cytometry and Western blot. Ionizing RT was compared at 5 doses: 0, 1.75, 3.5, 7, and 14 Gy. A single dose of 3.5 Gy was used for most experiments. Post-radiation effects were generally assessed at 3 days or 9 days post-RT. Intracellular staining was used to assess NK cell expression of IFN-γ, CD107a, and TNF-α by flow cytometry. CD27/CD70 interaction blockade was through α-CD27 pre-treatment of CAR-NK cells.

RESULTS

OQ01 HNSCCs heterogeneously express CD70 and are killed by CD70 CAR-NK cells in vitro. Pre-conditioning low-dose RT of 3.5 Gy applied to OQ01 HNSCCs 3 days prior to coculture with NK cells enhances CD70 CAR-NK cell killing, with ∼30% increased cytotoxicity against the tumor cells. Low-dose RT by itself did not induce acute cytolysis. As a possible mechanism for the increased sensitivity of irradiated OQ01 cells to CD70 CAR-NK cells, we found that RT enhances CD70 expression among HNSCCs in a dose-dependent manner. There was no increase in NK cell expression of IFN-γ, CD107a, and TNF-α with exposure to irradiated target cells. CD27/CD70 blockade does not solely abrogate RT-induced sensitization toward CAR-NK cell killing. Despite RT induction of transient increased expression of CD70, which normalizes by 9 days post-RT, there is persistent increase in RT-synergized target cell killing even at this later timepoint. Thus, altogether, RT sensitizes CD70-expressing HNSCC cells to CAR-NK cell killing in vitro.

CONCLUSION

This work represents the first preclinical study to identify the synergy of RT and CAR-NK cell therapy in solid tumors and is the first demonstration of CAR-NK cell activity against human HNSCCs. We show significantly enhanced potency of CAR-NK cells against irradiated tumor cells in vitro. Collectively, this research will be vital to guide efforts expanding into other target antigens and tumor types.

Ibrutinib modulates the immunosuppressive CLL microenvironment through STAT3-mediated suppression of regulatory B-cell function and inhibition of the PD-1/PD-L1 pathway

Ibrutinib, a covalent inhibitor of Bruton Tyrosine Kinase (BTK), is approved for treatment of patients with relapsed/refractory or treatment-naïve chronic lymphocytic leukemia (CLL). Besides directly inhibiting BTK, ibrutinib possesses immunomodulatory properties through targeting multiple signaling pathways. Understanding how this ancillary property of ibrutinib modifies the CLL microenvironment is crucial for further exploration of immune responses in this disease and devising future combination therapies. Here, we investigated the mechanisms underlying the immunomodulatory properties of ibrutinib. In peripheral blood samples collected prospectively from CLL patients treated with ibrutinib monotherapy, we observed selective and durable downregulation of PD-L1 on CLL cells by 3 months post-treatment. Further analysis showed that this effect was mediated through inhibition of the constitutively active signal transducer and activator of transcription 3 (STAT3) in CLL cells. Similar downregulation of PD-1 was observed in CD4+ and CD8+ T cells. We also demonstrated reduced interleukin (IL)-10 production by CLL cells in patients receiving ibrutinib, which was also linked to suppression of STAT3 phosphorylation. Taken together, these findings provide a mechanistic basis for immunomodulation by ibrutinib through inhibition of the STAT3 pathway, critical in inducing and sustaining tumor immune tolerance. The data also merit testing of combination treatments combining ibrutinib with agents capable of augmenting its immunomodulatory effects.

Cord blood NK cells engineered to express IL-15 and a CD19-targeted CAR show long-term persistence and potent antitumor activity

Chimeric antigen receptors (CARs) have been used to redirect the specificity of autologous T cells against leukemia and lymphoma with promising clinical results. Extending this approach to allogeneic T cells is problematic as they carry a significant risk of graft-versus-host disease (GVHD). Natural killer (NK) cells are highly cytotoxic effectors, killing their targets in a non-antigen-specific manner without causing GVHD. Cord blood (CB) offers an attractive, allogeneic, off-the-self source of NK cells for immunotherapy. We transduced CB-derived NK cells with a retroviral vector incorporating the genes for CAR-CD19, IL-15 and inducible caspase-9-based suicide gene (iC9), and demonstrated efficient killing of CD19-expressing cell lines and primary leukemia cells in vitro, with marked prolongation of survival in a xenograft Raji lymphoma murine model. Interleukin-15 (IL-15) production by the transduced CB-NK cells critically improved their function. Moreover, iC9/CAR.19/IL-15 CB-NK cells were readily eliminated upon pharmacologic activation of the iC9 suicide gene. In conclusion, we have developed a novel approach to immunotherapy using engineered CB-derived NK cells, which are easy to produce, exhibit striking efficacy and incorporate safety measures to limit toxicity. This approach should greatly improve the logistics of delivering this therapy to large numbers of patients, a major limitation to current CAR-T-cell therapies.

A unique anomaly of the fibrous sling of the digastric muscle

Anomalies of digastric muscle are not very rare. During a routine dissection, it was found on a cadaver that the digastric muscles on both sides had no fibrous slings. It was also observed that the two intermediate tendons crossed over the stylohyoid muscles. Such anomalies should be considered during the evaluation of the floor of the mouth after CT examination of MR imaging, and during surgical procedures as well.

A study of variations of transverse foramens of cervical vertebras in human: accessory foramina in shape and number

Transverse foramens of 250 cervical vertebras were examined. There were accessory foramina and variations in shape and number in 10 out of 250 cervical vertebras. Since such a variation of foramens, through which the vertebral artery passes, has not been detected in the literature, these ten cases are to be considered.

A connecting branch between the musculocutaneous nerve and the median nerve

We report here a connecting branch between the musculocutaneous and the median nerves in a 42 years old male cadaver. The connecting branch was 8 cm in length and 3 mm in width. One of the brachial veins and the brachial artery were located between the roots of the median nerve and the second brachial vein was present between the connecting branch and the median nerve. These kinds of variations may effect the venous return and may cause edema in the upper extremities. Additionally, variations of these nerves have an importance during operations of this region.

The comparison of the incidence of horseshoe kidney in autopsy cases versus urologic patient population

This study was applied on 9665 cases between January 1993 and October 1998. Of these, 6985 (72.3%) were urologic patients and 2680 (27.7%) were autopsy cases. The patients having urinary complaint investigated by urine analysis and kidney-ureter-bladder film (KUB), routinely. In all patients who have pathological urine, ultrasonography exam was done and in all patients who established an abnormality on ultrasonography, intravenous pyelography (IVP) was taken, also. We established the horseshoe kidney in 23 of patients (1/304) and in 6 of autopsy cases (1/447) with overall incidence 1/333. There were 21 male and 8 female with horseshoe kidney (male/female = 2.6/1). Abdominal discomfort with lower lumbar pain and Rovsing's sign were seen in 56.5% and in 65.2% of patients respectively. We concluded that horseshoe kidney incidence is almost the same as reported in the literature, although its clinical appearance is higher in our urologic patient population. In the urological out-patient evaluation, at least Rovsing's sign should be applied to all patients with lower lumbar pain with vague abdominal discomfort and an abdominal ultrasonographic exam should be applied, if this sign is positive.

Histopathological changes and nitric oxide synthase activity in corpus cavernosum from rats with neurogenic erectile dysfunction

OBJECTIVE

To investigate changes in histology and nitric oxide synthase (NOS) activity in cavernosal tissues from rats with neurogenic erectile dysfunction induced experimentally.

MATERIALS AND METHODS

Twenty-four adult male Sprague-Dawley rats were divided equally into three groups and underwent a sham operation (control, group 1), unilateral (group 2) or bilateral (group 3) cavernosal nerve resection. Three months later they were killed and the cavernosal tissues analysed histologically by light and transmission electron microscopy, with NOS activity detected using an NADPH-diaphorase staining technique.

RESULTS

On light and electron microscopy, while penile nerves and cavernosal smooth muscle cells had a normal morphological appearance in the eight control rats, there were degenerative changes of the myelinated penile nerves and axonal fibrosis in groups 2 and 3. However, these changes were not significant. Using NADPH-diaphorase staining, NOS activity was detected in all three groups in endothelial cells and cavernosal structures. However, the staining was more intense in endothelial cells and cavernosal muscles of rats in group 2 than in the other groups.

CONCLUSION

NOS activity was increased in the cavernosal tissue after cavernosal denervation, but the pharmacological action of nitric oxide may be impaired.

The marginal mandibular branch of the facial nerve

The peripheral, extraparotid course and localisation of the marginal mandibular branch of the facial n. is described, with variations, based on the dissection of 40 cadaver half heads. Its anatomical relationships with the ramus of mandible and facial a. are studied and morphometric features are reported. Knowledge of the accurate course and relationship of the marginal mandibular branch should help to protect this nerve from surgical injury.

An unusual insertion of accessory biceps brachii muscle

In the course of a routine dissection of the anterior region of the arm an accessory muscle was observed in the flexor aspect of the right arm of a 64-year-old male cadaver. This accessory muscle, which was considered to be the third head of the biceps brachii muscle originated from the inserting tendon of the deltoid muscle. The muscle gave rise to three tendons as it approached the cubital fossa. Two of these tendons inserted to the bicipital aponeurosis whereas the third tendon inserted to the ulnar head of the pronator teres muscle. Dissection of the forearm on both sides revealed that the palmaris longus muscles was absent bilaterally. Mechanical effects of the insertion tendons of the accessory head of the biceps brachii on the median nerve, especially during the supination of the forearm, are discussed. For radiodiagnostic procedures, MRI images of the accessory head were obtained in the coronal and axial planes.

Complex variation of the superficial palmar arch--case report

This article describes a complex variation in the pattern of blood supply to the palm of the hand. In the present case; a) the superficial palmar branch of the radial a. coursed superficial to the thenar mm.; b) The princeps pollicis and radialis indicis aa. arose from the superficial palmar branch of the radial a.; c) The first and second common palmar digital aa. arose as a common trunk from the superficial palmar arch.