Discovery of Macrocycle-Based HPK1 Inhibitors for T-Cell-Based Immunotherapy

Abstract

Hematopoietic progenitor kinase 1 (HPK1) is a negative regulator of T-cell activation, and targeting HPK1 is considered a promising strategy for improving responses to antitumor immune therapies. The biggest challenge of HPK1 inhibitor design is to achieve a higher selectivity to GLK, an HPK1 homology protein as a positive regulator of T-cell activation. Herein, we report the design of a series of macrocycle-based HPK1 inhibitors via a conformational constraint strategy. The identified candidate compound 5i exhibited HPK1 inhibition with an IC 50 value of 0.8 nM and 101.3-fold selectivity against GLK. Compound 5i also displayed good oral bioavailability (F = 27−49%) in mice and beagles and favorable metabolic stability (T 1/2 > 186.4 min) in human liver microsomes. More importantly, compound 5i demonstrated a clear synergistic effect with anti-PD-1 in both MC38 (MSI) and CT26 (MSS) syngeneic tumor mouse models. These results showed that compound 5i has a great potential in immunotherapy.

Targeting Arginine Methyltransferase PRMT5 for Cancer Therapy: Updated Progress and Novel Strategies

“…Cyclization is an effective strategy to develop novel lead compounds by increasing structural novelty, expanding scaffold diversity and taming complexity. − Lin et al at Prelude Therapeutics initiated a project to discover potent and selective PRMT5 inhibitors employing this cyclization strategy. The conformation of compound 1 was initially restricted via a five-membered ether in their new inhibitor design, as exemplified by compound 2 (Figure ).…”

2(1H)-Pyrazinones from acyclic building blocks: methods of synthesis and further derivatizations

“…6 ). 94 PB2 is a subunit of influenza RNA-dependent RNA polymerase and it is an important target for the design of anti-influenza drugs. The structure of these new 2(1 H )-pyrazinones was based on VX787 ( 66 ), a PB2 inhibitor that has entered phase III clinical trials, by replacing the pyrimidine ring with a pyrazinone moiety.…”

Design, Synthesis, and Pharmacological Evaluation of Isoindoline Analogues as New HPK1 Inhibitors

“…This compound was confirmed to suppress tumor growth by promoting anticancer immune responses in the 4T1 syngeneic mouse model . Compounds 2 – 6 were reported as selective HPK1 inhibitors with single-digit nanomolar or picomolar HPK1 inhibitory activity. ,− However, these compounds generally displayed moderate inhibition on the cellular phosphorylation of SLP76, a substrate of HPK1, and only compounds 2 and 6 were verified in vivo in the mouse model. In the MC38 syngeneic tumor model, compound 2 in combination with an anti-PD1 antibody displayed synergistic antitumor efficacy.…”

“…However, this compound suffered from poor metabolic stability both in mouse and human liver microsomes . Similarly, the macrocyclic compound 6 showed remarkable high potency against HPK1 with an IC 50 value of 0.8 nM, but modest potency was observed in the inhibition of the formation of pSLP76 (IC 50 , 0.6 μM) . All of these results indicated that most of the currently reported HPK1 inhibitors are not optimal for the clinical study.…”

“…26 Similarly, the macrocyclic compound 6 showed remarkable high potency against HPK1 with an IC 50 value of 0.8 nM, but modest potency was observed in the inhibition of the formation of pSLP76 (IC 50 , 0.6 μM). 29 All of these results indicated that most of the currently reported HPK1 inhibitors are not optimal for the clinical study. Therefore, the design and synthesis of new HPK1 inhibitors with an improved PK profile as well as high potency both in vitro and in vivo are highly needed.…”