898 Intratumoral administration of NL-201, an alpha-independent IL-2/15 receptor agonist, inhibits the growth of both injected and uninjected tumors in preclinical models

BackgroundNL-201 is a potent, selective, and long-acting computationally designed alpha-independent agonist of the IL-2 and IL-15 receptors that is being developed as an immunotherapy for cancer. Intravenous NL-201 administration is active in numerous pre-clinical tumor models. Here, we report data demonstrating favorable tolerability, pharmacokinetics, and antitumor activity of NL-201 after intratumoral (IT) administration in syngeneic murine tumor models.MethodsMice were implanted with syngeneic colorectal tumors in a single tumor (right flank) or bilateral tumor model (right and left flank). Once tumors were established, mice were randomized to receive IT or intravenous (IV) NL-201, or IV vehicle as control. Tumor volumes (mm3) and bodyweights were measured twice weekly, and mice were monitored for abnormal clinical signs. Blood samples were collected at pre-specified time points, and serum was analyzed for NL-201 concentration using a ligand-binding assay. Toxicokinetic parameters were determined using a non-compartmental model consistent with the IT and IV routes. Animals were sacrificed if tumor sizes reached 2000 mm3 or if body weight loss was >20%. In the bilateral tumor models, surviving tumor-free animals from both the IT and IV treatment arms were rechallenged with tumor cells after a washout period to assess antitumor immune responses.ResultsIT NL-201 demonstrated dose-dependent antitumor activity and was well tolerated based on a lack of clinical observations and body weight changes at doses up to 10 µg/mouse. Comparable antitumor activity was observed in mice receiving 3 μg/mouse NL-201 via IV or IT routes, but reduced systemic exposure and better tolerability were observed after IT administration. The estimated absolute bioavailability following 3 µg/mouse IT administration was 19.4%–66.5% of the NL-201 IV exposure. In the bilateral tumor model, IT NL-201 resulted in significant antitumor activity in both the treated and untreated tumors. Surviving animals from both IT and IV groups in which the initial tumors regressed rejected engraftment of the same tumor cell line upon rechallenge.ConclusionsIT NL-201 administration resulted in dose-dependent antitumor activity in both injected and uninjected tumors while demonstrating markedly reduced systemic exposure and improved tolerability compared to systemic administration at equivalent dose levels. Rechallenged animals failed to develop tumors, demonstrating durable tumor-specific immunity after IT NL-201 treatment. Results of this study support planned clinical investigation of IT NL-201 administration to increase NL-201 concentrations in accessible lesions.Ethics ApprovalThis study was approved by the Institutional Animal Care and Use Committee (IACUC) of CrownBio.

Bilateral Spontaneously Resolving Galactocele in an 18 Month Old Boy: A Case Report

Galactoceles in children, either cystic or pseudotumors, are described in the literature as a rare cause of increasing breast size and can appear in males. We report a case of galactocele in a 18-month-old male, treated at our institution. The patient presented with bilateral tumor breast that had appeared 6 months earlier with no pain, signs of inflammation, or nipple secretion. Twenty-nine cases found in the literature emphasize the importance of including galactocele in the differential diagnosis of benign breast masses in infancy.

A bilateral tumor model identifies transcriptional programs associated with patient response to immune checkpoint blockade

Immune checkpoint blockade (ICB) is efficacious in many diverse cancer types, but not all patients respond. It is important to understand the mechanisms driving resistance to these treatments and to identify predictive biomarkers of response to provide best treatment options for all patients. Here we introduce a resection and response-assessment approach for studying the tumor microenvironment before or shortly after treatment initiation to identify predictive biomarkers differentiating responders from nonresponders. Our approach builds on a bilateral tumor implantation technique in a murine metastatic breast cancer model (E0771) coupled with anti-PD-1 therapy. Using our model, we show that tumors from mice responding to ICB therapy had significantly higher CD8+T cells and fewer Gr1+CD11b+myeloid-derived suppressor cells (MDSCs) at early time points following therapy initiation. RNA sequencing on the intratumoral CD8+T cells identified the presence of T cell exhaustion pathways in nonresponding tumors and T cell activation in responding tumors. Strikingly, we showed that our derived response and resistance signatures significantly segregate patients by survival and associate with patient response to ICB. Furthermore, we identified decreased expression of CXCR3 in nonresponding mice and showed that tumors grown inCxcr3−/−mice had an elevated resistance rate to anti-PD-1 treatment. Our findings suggest that the resection and response tumor model can be used to identify response and resistance biomarkers to ICB therapy and guide the use of combination therapy to further boost the antitumor efficacy of ICB.

Tumors attenuating the mitochondrial activity in T cells escape from PD-1 blockade therapy

PD-1 blockade therapy has revolutionized cancer treatments. However, a substantial population of patients is unresponsive. To rescue unresponsive patients, the mechanism of unresponsiveness to PD-1 blockade therapy must be elucidated. Using a ‘bilateral tumor model’ where responsive and unresponsive tumors were inoculated into different sides of the mouse belly, we demonstrated that unresponsive tumors can be categorized into two groups: with and without systemic immunosuppressive property (SIP). The SIP-positive tumors released uncharacterized, non-proteinaceous small molecules that inhibited mitochondrial activation and T cell proliferation. By contrast, the SIP-negative B16 tumor escaped from immunity by losing MHC class I expression. Unresponsiveness of SIP-positive tumors was partially overcome by improving the mitochondrial function with a mitochondrial activator; this was not successful for B16, which employs immune ignorance. These results demonstrated that the ‘bilateral tumor model’ was useful for stratifying tumors to investigate the mechanism of unresponsiveness and develop a strategy for proper combination therapy.

Tumors attenuating the mitochondrial activity in T cells escape from PD-1 blockade therapy

PD-1 blockade therapy has revolutionized cancer treatments. However, a substantial population of patients is unresponsive. To rescue unresponsive patients, the mechanism of unresponsiveness to PD-1 blockade therapy must be elucidated. Using a ‘bilateral tumor model’ where responsive and unresponsive tumors were inoculated into different sides of the mouse belly, we demonstrated that unresponsive tumors can be categorized into two groups: with and without systemic immunosuppressive property (SIP). The SIP-positive tumors released uncharacterized, non-proteinaceous small molecules which inhibited T cell proliferation and mitochondrial activation. By contrast, the SIP-negative B16 tumor, escaped from immunity by losing MHC class I expression. Unresponsiveness of SIP-positive tumors was partially overcome by improving the mitochondrial function with a mitochondrial activator; this was not successful to B16, which employs immune ignorance. These results demonstrated that our ‘bilateral tumor model’ was useful for stratifying tumors to investigate the mechanism of unresponsiveness and develop strategy for proper combination therapy.

Bilateral Rhabdomyomatous Tumor Relapsed as Typical Triphasic Wilms’ Tumor

The authors report on a child affected with bilateral renal tumor, which was treated with cancer chemotherapy before and after surgery. Twenty-eight months after the discontinuance of therapy, a neoplasm was disclosed in the left kidney and then removed. Histologically, the bilateral tumor excised by the first surgery could be classified as biphasic Wilms’ tumor, rhabdomyomatous variant, whereas the neoplasm removed by the second surgery was the typical triphasic Wilms’ tumor. The authors suggest that preoperative chemotherapy might have played a role in the histologic changes of the initial tumor. Nonetheless, it is also tempting to postulate that the two histologic variants of Wilms’ tumor could have occurred in the patient in spite of any treatment.