On June 9, 2022 Sonnet BioTherapeutics Holdings, Inc. (NASDAQ:SONN) ("Sonnet" or the "Company"), a biopharmaceutical company developing innovative targeted biologic drugs, reported data from a preclinical combination study of SON-1010 with a commercially available anti-PD1 compound (Press release, Sonnet BioTherapeutics, JUN 9, 2022, View Source [SID1234615826]). These results suggest that dosing of SON-1010 (IL12- FHAB) in combination with anti-PD1 demonstrated strong efficacy in the B16F10 mouse melanoma model, historically known as an immunologically insensitive model to anti-PD1.

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Checkpoint inhibitors provide viable treatment alternatives to chemotherapy and/or radiation for patients with solid tumors, but there remains a robust need for more effective combination treatment regimens. With the objective of improving the checkpoint inhibitor response rate, Sonnet BioTherapeutics is developing a targeted approach using the company’s Fully Human Albumin binding (FHAB) platform. The FHAB technology targets tumor and lymphatic tissue, providing a mechanism for dose sparing and an opportunity to improve the safety and efficacy profile of not only Interleukin 12 (IL-12), but a variety of synergistic and potent immunomodulators. SON-1010 is currently undergoing Phase 1 clinical study in cancer patients and this preclinical study was designed to explore the combination potential with a checkpoint inhibitor (anti-PD1).

"We are excited to see that the combination of SON-1010 with an anti-PD1 antibody yielded compelling data in this preclinical model" said Pankaj Mohan, Ph.D., Sonnet Founder and Chief Executive Officer, and further added that, "These data support our strategy of pairing SON-1010 with a checkpoint inhibitor, with the goal of developing an improved treatment option for cancer patients."

Experimental Study Design: Three randomized cohorts of nine mice (n = 27), each with 150 mm3 B16F10 melanoma tumors, were dosed with 3µg IL12-FHAB and/or 10µg anti-PD1 antibody on days 0, 4 and 8 while the placebo cohort was not treated. Mean tumor volumes were measured every two or three days through an 18-day period.

Table 1: Mean Comparisons of Tumor Volume Growth Inhibition

Test Article

Mean Tumor
Volume (mm3) – Day 14

Tumor Growth Inhibition Ratios
( % Inhibition )

Placebo (n = 9)

2260

–

Anti-PD1 antibody (n = 9)

2016

10.7%

Anti-PD1 + IL12-FHAB (n = 9)

472

79.1%

Compared to the tumor-bearing placebo group at day 14, the treatment groups administered three doses of anti-PD1 antibody or three doses of the IL12-FHAB + anti-PD1 antibody combination resulted in 10.7% and 79.1% tumor growth inhibition, respectively.

Survival data for study mice at 18 days further supports the efficacy synergy of IL12-FHAB co-injected with anti-PD1 by improving the survival rate: (i) for anti-PD1 administration, only one mouse survived out of a total of nine, and (ii) for anti-PD1 + IL12-FHAB administration, seven mice survived out of a total of nine. Additionally, the mice cohorts used in the preclinical efficacy study did not show any weight loss during the study in either the single agent or combination dosing arms.

"We are excited to have demonstrated these important data in an immunologically distinct animal model when IL12-FHAB was dosed in combination with an anti-PD1 antibody," said John Cini, Ph.D., Sonnet’s Chief Scientific Officer. "Further, this study evaluated the sequence of test article administration, whereby co-injection of IL12-FHAB and anti-PD1 antibody was optimal when compared to administration of either anti-PD1 or IL12-FHAB first. Targeting the tumor by linking IL-12 to an albumin-binding domain extends the cytokine half-life in the body, and we believe that is the key to inducing a successful local immune response in the tumor microenvironment."