prexasertib (ACR-368)

P2, N=72, Recruiting, Acrivon Therapeutics | N=48 --> 72

P1/2, N=48, Not yet recruiting, Acrivon Therapeutics Inc.

A2780ADR cells revealed cross‑resistance to multiple compounds, including anticancer drugs [cisplatin (CisPt) and etoposide (Eto)] and DNA repair/DNA damage response (DDR) inhibitors (olaparib, niraparib, entinostat, prexasertib and rabusertib). However, combination treatment with Doxo and Ver also increased the cytotoxic response of non‑malignant murine cardiomyocytes, murine embryonic stem cells and human induced pluripotent stem cells. Taken together, the present study suggested inhibition of MDR1‑mediated Doxo efflux by Ver a useful approach to overcome acquired drug resistance of A2780ADR cells by stimulating DDR‑related cytotoxicity, yet at the price of a potentially increased risk of normal tissue toxicity.

We identified strong synergism for combined RRM2-CHK1 inhibition using the iron chelator triapine and prexasertib respectively. We confirm drug synergism in vivo in a NB zebrafish xenograft model, further underscoring the broad clinical potential of combinatorial RRM2-CHK1 inhibition. Altogether, this study paves the way for further preclinical testing of second generation RRM2 and CHK1 inhibitors such as TAS1553 and SRA737 in neuroblastoma and sarcomas.

Co-treatment with interferon-γ further amplified PD-L1 and γH2A.X expression, highlighting a link between CHK1 inhibition, DNA damage, and immune checkpoint modulation. These findings suggest that Prexasertib not only enhances the cytotoxic effects of cisplatin but also influences immune signaling, providing a mechanistic rationale for future exploration of combined DNA damage response inhibition with immune checkpoint blockade.

Dual targeting of CHK1 and PD-L1 may improve OC treatment by simultaneously suppressing stemness and enhancing anti-tumor immunity.

FSTL3 overexpression completely abrogated tumor response to PPC treatment (Prexasertib combined with PD-1 and CTLA-4 blockade) compared to controls, suggesting that FSTL3 may be involved in immunotherapy resistance. In conclusion, this study suggests a role for FSTL3 as a prognostic marker and as therapeutic target in HGSOC, where it may play a role in promoting a mesenchymal tumor phenotype, maintaining an immunosuppressive tumor microenvironment, and driving immunotherapy resistance.

Furthermore, combining Prexasertib with 5-fluorouracil, a standard chemotherapeutic agent, produced a synergistic killing effect. These findings establish a novel synthetic lethal relationship between FBXO7 and CHEK1, suggesting that CHEK1 inhibition may provide a targeted therapeutic strategy for CRC patients with FBXO7 deficiencies, and highlighting the broader potential of exploiting SCF complex alterations in CRC therapy.

Strikingly, three HRP subtypes emerged, marked by unique structural alterations and gene expression patterns, tumor microenvironment interactions, and different chemotherapy responses. Finally, organoid experiments showed subtype-specific sensitivity to CHK1 inhibition, suggesting prexasertib as a potential targeted treatment for most currently untreatable HRP patients.

P2, N=353, Recruiting, Acrivon Therapeutics | Phase classification: P1/2 --> P2 | Trial completion date: Dec 2027 --> Apr 2027 | Trial primary completion date: Jul 2026 --> Oct 2026

The potential of novobiocin, recently identified to be a DNA POLѲ inhibitor, to augment cancer chemotherapy was explored in the late 1980s and early 1990s in tumor cells, tumor-bearing mice and in Phase 1 clinical trial in combination with cyclophosphamide or cisplatin...In simultaneous combination with ART-558, talazoparib produced greater-than-additive cytotoxicity at the highest concentrations of the POLѲ inhibitors in the 922,993-354-T-J3-PDC endometrial serous carcinoma mct-spheroids. Activity of the Chk1/2 inhibitor prexasertib was potentiated by either ART-558 or RP6685 in the 922,993-354-T-J3 mct-spheroids...Regions of potentiation were evident in the 922,993-354-T-J3-PDC endometrial carcinoma survival surface plots at the highest concentration of paclitaxel tested, while regions of potentiation were evident in the paclitaxel mid-concentrations of the 299,254-011-R-J1-PDC melanoma mct-spheroids survival surface plots as determined by the Bliss independence calculation...POLѲ allosteric inhibitors, novobiocin, ART558 and RP-6685, have entered clinical trial. The current study explores the cytotoxicity of POLѲ inhibitors in combination with anticancer drugs and investigational agents in patient-derived cell lines grown as mct-spheroids.

A therapy with anti-N1/prexasertib could represent a novel treatment strategy, alone or in combination with current treatment regimens, for melanoma brain metastases.