8-K: Acrivon's ACR-368 Shows Strong Efficacy in Endometrial Cancer

Acrivon Therapeutics presented positive interim Phase 2b data for ACR-368 in endometrial cancer, particularly in the serous subtype, highlighting significant objective response rates and a favorable safety profile.

Summary

• Acrivon Therapeutics held a Key Opinion Leader (KOL) panel to discuss interim data from its ACR-368 Phase 2b registrational-intent trial for endometrial cancer.
• ACR-368 is a potent, selective CHK1/2 inhibitor, with patient selection guided by the OncoSignature biomarker test.
• In Arm 1 (BM+), the Objective Response Rate (ORR) was 39% (95% CI, 24-56) in patients with high-grade EC and 3 prior lines of therapy.
• A higher ORR of 44% (95% CI, 27-63) was observed in BM+ patients with 2 prior lines of therapy.
• For the serous all-comer population with 2 or more prior lines of therapy, ACR-368 demonstrated a significant ORR of 52% (95% CI, 33-71).
• The drug exhibited a favorable safety profile, with limited, transient, mechanism-based hematological adverse events and a notable absence of severe GI, pulmonary, or neurological toxicities.
• The study is expanding to over 20 sites in four major EU countries, with enrollment completion anticipated by Q4 2026.

Sentiment

Score: 8

Explanation: StockSavvy.ai views this as a highly positive update given the strong efficacy data in a high unmet need population (serous endometrial cancer) and a favorable safety profile, suggesting significant potential for ACR-368.

Positives

• Significant Objective Response Rate (ORR) of 39% in the BM+ ITT population.
• Even higher ORR of 44% in BM+ patients with 2 prior lines of therapy.
• Particularly strong ORR of 52% in the serous all-comer population with 2 or more prior lines of therapy, addressing a high unmet medical need.
• Favorable safety profile with limited Grade 3/4 hematological adverse events and absence of common severe toxicities like GI, pulmonary, or neurological issues.
• ACR-368 is active in both BM+ and serous endometrial cancer, indicating broad potential.
• The OncoSignature biomarker test effectively predicts benefit from ACR-368.

Negatives

• Arm 2 (BMwith ULDG sensitization) showed a lower ORR of 26% compared to Arm 1 (BM+) with 2 prior lines of therapy.
• Non-serous patients with 2 prior lines of therapy showed a lower ORR of 22% compared to serous patients.
• Some Grade 3/4 hematological adverse events (thrombocytopenia, anemia, leukopenia, neutropenia, febrile neutropenia) were observed, though described as limited and transient.

Risks

• Forward-looking statements are subject to risks and uncertainties, including factors described in SEC filings.
• New risks and uncertainties may emerge, and actual results could differ materially from forward-looking statements.
• The outcome of clinical trials is inherently uncertain, and there is no guarantee that ACR-368 will achieve its primary endpoints or regulatory approval.
• The potential for rapid resistance and early recurrence in serous endometrial cancer, as seen with current treatments, could also affect ACR-368's long-term efficacy.

Future Outlook

The company plans to complete enrollment for the expanded ACR-368 trial, including Arm 3 in serous endometrial cancer patients across US and EU sites, by Q4 2026. The trial aims to address the significant unmet need in serous endometrial cancer, which accounts for a disproportionate share of endometrial cancer deaths and has limited effective treatment options.

Management Comments

• ACR-368 is active in BM+ EC.
• Serous EC shows particularly high ORR in both BM+ and BMtumors.
• ACR-368 has a favorable safety profile.
• Arm 3 is evaluating ACR-368 with ULDG in serous EC all-comer (biopsy-independent) population with 2 prior LoT.
• The study is being expanded to >20 EU sites.

Industry Context

StockSavvy.ai notes that serous endometrial cancer represents a high unmet medical need, accounting for approximately 40% of all endometrial cancer deaths despite being a smaller subset of cases. Current second-line standard of care post-immunotherapy/platinum chemotherapy offers only about a 15% Objective Response Rate (ORR) and 3.4 months Progression-Free Survival (PFS) with single-agent chemotherapy. The strong ORR of 52% observed with ACR-368 in this difficult-to-treat population, especially compared to the 15% ORR of existing therapies, suggests a potentially significant advancement in treatment options for this aggressive subtype.

Comparison to Industry Standards

• The observed ORR of 52% in serous endometrial cancer patients with 2 prior lines of therapy for ACR-368 significantly surpasses the typical ~15% ORR seen with single-agent chemotherapy, which is the standard of care in the second line post-IO/platinum therapy for this patient population.
• The favorable safety profile, characterized by limited hematological adverse events and the absence of common severe toxicities like GI, pulmonary, or neurological issues, compares favorably to the broader toxicity profiles often associated with traditional chemotherapy regimens.

Stakeholder Impact

• Shareholders: Positive interim clinical data, especially in a high unmet need area, could increase investor confidence and potentially lead to share price appreciation.
• Patients: ACR-368 shows promise as a new, more effective treatment option for patients with advanced endometrial cancer, particularly the aggressive serous subtype, where current options are limited and outcomes are poor.
• Medical Community: The data provides new insights into treating endometrial cancer and validates the potential of CHK1/2 inhibition and the OncoSignature biomarker.

Next Steps

• Continue enrollment for the ACR-368-201/GOG-3082 trial, including expansion to over 20 sites in four major EU countries.
• Anticipate completion of enrollment for the expanded trial by Q4 2026.
• Further evaluation of ACR-368 with ULDG sensitization in the serous EC all-comer (biopsy-independent) population (Arm 3).

Key Dates

Recommendation

The interim Phase 2b data for ACR-368 demonstrates compelling efficacy, particularly an Objective Response Rate of 52% in the highly aggressive and underserved serous endometrial cancer subtype, significantly outperforming current standard of care. Coupled with a favorable safety profile and the strategic expansion of the trial, this positions ACR-368 as a potential breakthrough therapy. The high unmet medical need and strong clinical signal suggest a substantial market opportunity and a high probability of future success, warranting a strong buy recommendation for long-term investors.

Keywords

Acrivon Therapeutics, ACRV, ACR-368, Endometrial Cancer, Serous Endometrial Cancer, Phase 2b Trial, OncoSignature, CHK1/2 Inhibitor, Oncology, Clinical Data, Biomarker, Gynecological Oncology, SEC Filing, Biotechnology