AVM0703 is a high concentration (24 mg/mL) dexamethasone phosphate drug product that permits the safe administration of the doses necessary to mobilize gamma delta+, bi-specific natural killer T (NKT) cells. AVM0703 is in clinical trials as a stand-alone treatment for relapsed/refractory (R/R) Non-Hodgkin's Lymphoma (NHL). Even more exciting is the potential combination of AVM0703 with standard chemotherapy to reduce the number of treatment cycles while maintaining efficacy. A therapeutic solution that reduces the number of chemotherapy cycles could lower the risk of secondary malignancies, decrease long-term toxicities, and limit costs associated with management of chemotherapy toxicities. AVM0703 has been well tolerated to date, with mild to moderate and self-limiting side effects. This indicates the use of AVM0703 in combination therapies may greatly improve quality of life for patients during treatment. AVM0703 has been tested in an aggressive mouse B-cell lymphoma model (A20) alone and in combination with cyclophosphamide/fludarabine (CyFlu). The tumor killing effect of AVM0703 on A20 cells in Matrigel TM embedded tumors is evident as early as 3 hours after dosing, assessed by flow cytometry. Maximum A20 cell death is observed 24 hours after treatment in blood (Figure 1) and between 3- and 24-hours in tumors (Figure 2). Treatment with AVM0703 alone was compared with Cy/Flu alone and with a combination of single dose AVM0703 followed by one Cy/Flu cycle. Tumor growth was monitored by caliper measurements and blood and tumors were analyzed by flow cytometry at the end point, 7-days after Cy/Flu dosing. AVM0703 alone was superior to one cycle of Cy/Flu and the combination of a dose of AVM0703 followed by Cy/Flu was the most effective (Figure 3). Of the mice treated with the combination, 33% had no visible tumor 7-days post-dose. We are currently testing AVM0703 administered between 6- and 24-hours before a single Cy/Flu dose and predict that A20 eradication should be more complete in all compartments. Acute 7 day studies will be followed by long-term studies to evaluate A20 tumor escape or recurrence. In previous studies with long term monitoring of tumor growth, AVM0703 administered 3 days before one cycle of Cy/Flu induced long-term stable disease up to 50 days in tumor bearing mice (Figure 4a) compared to two cycles of Cy/Flu where 33% of the tumors escaped (Figure 4b). Additional studies in combination with R-CHOP are underway. AVM0703 has the ability to debulk the tumor by mobilizing gamma delta+, bi-specific natural killer T (NKT) cells. When added to a chemotherapeutic regimen, the chemotherapy may be more effective due to the lower tumor burden in the body. As cancer survivors live longer, the late term consequences of chemotherapy have become apparent, which include secondary malignancies. The challenge for new treatments is to reduce toxicities without sacrificing efficacy. AVM0703 has the potential to be one solution when used in combination with chemotherapy. Future clinical trials will determine if debulking with AVM0703 results in a reduction of the number of necessary R-CHOP cycles while maintaining or enhancing the efficacy rate. Figure 1 Figure 1. Disclosures Deisher: AVM Biotechnology, LLC: Current Employment. Sawas: AVM Biotechnology, LLC: Current Employment. Suwito: AVM Biotechnology, LLC: Current Employment. Rylatt: AVM Biotechnology, LLC: Current Employment. Jarzyna: AVM Biotechnology, LLC: Current Employment. Zahid: AVM Biotechnology, LLC: Ended employment in the past 24 months. Parthasarathy: AVM Biotechnology, LLC: Consultancy, Ended employment in the past 24 months. Poulin: AVM Biotechnology, LLC: Current Employment. Lee-Diaz: AVM Biotechnology, LLC: Current Employment.

2579 Background: Glucocorticoids (GC) are a common component of blood cancer regimens, typically at doses 40 mg or lower due to concerns of pancreatitis and hepatotoxicity (Walasik-Szemplińska et al. Thyroid Research. 2019;12:13; Ataallah et al. Cureus. 2020;12[7]) and neuropsychiatric effects. AVM Biotechnology has developed a high concentration, high volume, preservative-free, patent pending formulation of dexamethasone (AVM0703), that allows administration of up to 21 mg/kg (1470 mg for 70 kg) over a one-hour IV infusion. Prophylactic use of circadian physiologic hydrocortisone reduces the risk of GC neuropsychiatric side-effects (Warris LT, et al. J. Clin. Oncol. 2016;34:2287; Meijer & de Kloet Endocrinology. 2017;158:448). Acute supra-pharmacologic doses (>6 mg/kg) AVM0703 mobilizes endogenous bispecific gamma delta invariant TCR+ bi-specific Natural Killer T-like cells (AVM-NKT) (PCT/US21/19773), via a non-GC receptor, that rapidly home to diseased organs in preclinical models and are directly related to tumor killing, including Non-Hodgkin’s Lymphoma, Melanoma, and Multiple Myeloma. Methods: Cancer cell lines and (mouse host) were i) immune-resistant mouse A20 B lymphoma (Balb/c), ii) xenografted human T-ALL CCRF-CEM (NCRnu), iii) mouse B16F10 melanoma (B62DF1), and iv) mouse MOPC315 (Balb/c). Cancer cell lines were inoculated into the flank either as single cell suspensions or encased in Matrigel. When tumor volume reached between 100-500mm3 well-established tumors, mice were orally gavaged with a human equivalent dose (HED) of 15-18 mg/kg AVM0703 as monotherapy, or as a preconditioning prior to adoptive cell transfer (ACT), or in combination with chemotherapy. Responses were determined by tumor volume measurements, tumor immunohistochemistry or flow cytometry detection of residual cancer cells. Results: Immunohistochemistry analysis of tumors from AVM0703 treated mice demonstrated pseudoprogression similar to checkpoint inhibitors: i.e. tumors were measurable however in some cases all cancer cells had been eradicated. Therefore, subsequent tumor monitoring at end point was done by flow cytometry to quantify the total number of live cancer cells more accurately than tumor measurements by calipers or immunohistochemistry, due to pseudoprogression and limitations of examining only a few sections from each tumor. Conclusions: AVM0703 led to: i) complete response (CR) in 27% of immune-resistant mouse A20 tumors as monotherapy and CR in 60% when combined with 2 doses of cyclophosphamide/fludarabine (CyFlu); ii) tumor eradication and long-term memory against xenografted human T-ALL; iii) enhancement of ACT equivalent to CyFlu preconditioning in mouse melanoma; and iv) preliminary 95% CR against mouse multiple myeloma.

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e14545 Background: Glucocorticoids (GC) are a common component of blood cancer regimens, at doses 40 mg or lower due to concerns of pancreatitis and hepatotoxicity (Walasik-Szemplińska et al. Thyroid Research (2019) 12:13; Ataallah et al. Cureus. 2020 Jul; 12(7)) and neuropsychiatric effects. AVM Biotechnology has developed a high concentration, high volume, preservative-free, patent pending formulation of dexamethasone (Dex) (AVM0703), allowing administration up to 21 mg/kg (1470 mg for 70 kg) in one-hour IV infusion. Prophylactic use of physiologic hydrocortisone reduces the risk of GC neuropsychiatric side-effects (Warris, L. T. et al. J. Clin. Oncol. (2016) 34:2287; Meijer & de Kloet Endocrinology (2017) 158:448). At supra-pharmacologic doses (>6 mg/kg) AVM0703 mobilizes endogenous bispecific gamma delta invariant TCR+ Natural Killer T-like cells (AVM-NKT) (PCT/US21/19773), via a non-GC receptor, that rapidly home to cancer in tumor models and are directly related to tumor killing. GCs have been reported to induce biological responses independent of GCRs: corticosterone has been shown to bind a G-protein coupled receptor that does not bind either Dex or aldosterone (Mitre-Aguilar, et. Al International Journal of Clinical and Experimental Pathology (2015) 8:1; Powell, C. E., et. Al. Endocrine (1999) 10: 271) and the non-GCR mineralocorticoid receptor has high affinity for prednisone but not Dex. Methods: a) Mouse splenocytes or human whole blood were incubated with Dex from 1nM to 1mM. Apoptosis was measured for human whole blood by CBCs and for mouse splenocytes by flow cytometry 4 to 6 hours later. RU486 was used to block expected transmembrane (tm)GCR activity. b) Naïve, tumor bearing and humanized mice were dosed with AVM0703 at human equivalent doses (HED) >18 mg/kg. Depending on the disease state of the mice, novel AVM-NKT were observed in the blood between 3 and 96 hours later, determined by flow cytometry. Results: a) Apoptosis via the tmGCR was observed at expected concentrations between 10nM and 100uM and was blocked by the GCR antagonist RU486. At concentrations above 250uM, which correspond to in vivo peak blood levels from acute 7mg/kg and greater, no Dex-induced apoptosis was observed. b) Acute supra-pharmacologic AVM0703 induced the appearance of CD3+, CD56+, gdTCR+, invariant TCR+ bi-specific Natural Killer T-like cells, that in a cancer setting also expressed activation markers like CD16 and NKp44. Intriguingly, the AVM-NKT also express B220 in certain settings, and CD3+ B220+ DP has been indicative of IL-2 or IL-12 lymphoma killing (Masztalerz, A, et. Al. Anticancer Res (2004) 24(5A):2633). Conclusions: CBC’s and clinical chemistries from enrolling clinical trial confirmed the in vitro non-GCR findings.

e14585 Background: Immune checkpoint inhibitors are approved to treat a variety of solid tumors and Hodgkin’s Lymphoma. However, they have not been shown to be effective against Non-Hodgkin’s Lymphoma (NHL). Unfortunately, their use is associated with induction of autoimmune reactions, termed immune mediated side-effects (irAEs) (1-3). AVM0703 is an immunomodulatory drug which mobilizes bispecific gd and invariant TCR double-positive NKT-like cells (AVM_NKT), currently enrolling a Phase 2 clinical trial to treat R/R NHL of all subtypes based on strong activity against the aggressive, immune-resistant mouse A20 lymphoma. Unlike the checkpoint inhibitors which trigger irAEs, gdTCR expression of the AVM0703 mobilized AVM_NKT, suggests that AVM0703 should not trigger irAEs, and in fact might be a treatment for autoimmune diseases such as type 1 diabetes (T1D). As monotherapy in the A20 lymphoma model, AVM0703 completely eradicates ~20% of flank tumors, and used as a neoadjuvant prior to cyclophosphamide/fludarabine (CyFlu) it provided additive/synergistic A20 killing. As a single dosed monotherapy, AVM0703 prevented T1D onset in the gold standard NOD model. Reversal of already established T1D has proven difficult, and monotherapy approaches abandoned for lack of efficacy. Based on its activity in combination with CyFlu, and since teplizumab anti-CD3 has been approved to prevent progression to grade 3 T1D in at risk people (4), we investigated the combination with AVM0703 to reverse recent onset T1D in the NOD mouse. Methods: One hundred twenty hyperglycemic non-obese diabetic (NOD) mice were randomized to receive an insulin pellet followed by 1) Oral Placebo (18 mg/kg HED) 2) 5 µg anti-CD3 (for 5 days) i.p. 2) Oral AVM0703 (18 mg/kg HED) – weekly/biweekly/tri-weekly 3) AVM0703 (18 mg/kg HED) followed by 5 µg anti-CD3 (for 5 days) and then AVM0703 – weekly/bi-weekly/tri-weekly. Mice were monitored for body weight, body condition and hyperglycemia. Results: Timing between 18 mg/kg AVM0703 and 5 ug anti-CD3 dosing was taken from lymphoma studies that demonstrated that chemotherapy 3 and 24 hours after AVM0703 dosing maximally eradicated lymphoma. The combinations of AVM0703 (day 1) and anti-CD3 (day 2-6) were able to reverse diabetes in 26 mice for 0-9 weeks, with six mice in ongoing normoglycemia at the time of this report. The combination group that received weekly AVM0703 dosing was more effective than the bi-weekly or tri-weekly AVM0703 groups. Monotherapy with AVM0703 did not reverse diabetes, in contrast to its profound ability to prevent or delay diabetes onset in the NOD model. Conclusions: We hypothesize that the combination of AVM0703 and anti-CD3 will be more effective when anti-CD3 is added 5 days after AVM0703. 1) Tocut, Autoimmun Rev 2018. 2) Sakowska, Front Immunol 2022. 3) Sherry, Lancet. 2011. 4) Hagopian, Diabetes 2013.