Intensity Therapeutics Reports Promising Early Results for INT230-6 in Triple-Negative Breast Cancer Phase 2 Trial
Key Insights
Intensity Therapeutics' INVINCIBLE-4 Phase 2 study shows 71.4% pathological complete response rate with INT230-6 plus standard care versus 33% with standard care alone in triple-negative breast cancer (search) patients.
The combination therapy demonstrated 44% fewer grade 3 or higher adverse events compared to standard immunochemotherapy alone, suggesting improved safety profile.
The company has submitted a protocol amendment to Swiss regulators to resume enrollment after addressing skin irritation issues with modified dosing parameters.
Intensity Therapeutics has reported encouraging preliminary results from its INVINCIBLE-4 Phase 2 study evaluating INT230-6 in combination with standard immunochemotherapy for presurgical triple-negative breast cancer (search) (TNBC (search)). The data shows a pathological complete response (pCR) rate of 71.4% in patients receiving INT230-6 prior to standard of care treatment, compared to 33% in patients receiving standard care alone.
Study Design and Patient Population
The INVINCIBLE-4 study is a Phase 2 non-comparative, randomized open-label, two-cohort multicenter trial analyzing INT230-6's clinical activity, safety, and tolerability in patients with early-stage, operable TNBC (search). The study compares INT230-6 followed by standard immunochemotherapy (Cohort A) against standard care alone (Cohort B). The primary endpoint is pathological complete response rate, defined as the absence of cancer at the time of surgery in both tumor and lymph nodes.
Fourteen patients have been treated to date, with seven in each cohort. The expected total enrollment is up to 61 patients. The study enrollment criteria is limited to patients with tumor sizes ≥ 1.5 cm, whereas the benchmark Keynote-522 study enrolled tumors > 1.0 cm, meaning INVINCIBLE-4 patients have larger tumors on average.
Efficacy Results
In Cohort A, five out of seven patients (71.4%) achieved a pCR after receiving INT230-6 injections prior to standard care. Six patients received two injections and one patient, who achieved a pCR, received one injection. In Cohort B, two out of six patients (33%) achieved a pCR with standard care alone, with one patient still to be evaluated.
The standard of care in the study follows the Keynote-522 regimen, a 6-month presurgical treatment consisting of pembrolizumab every three weeks, followed by paclitaxel, then carboplatin and doxorubicin or epirubicin with cyclophosphamide.
Safety Profile Improvements
The safety data through March 2, 2026, revealed significant differences between treatment arms. Cohort A experienced 14 grade 3 or higher adverse events, with only one considered a common immune-related side effect of checkpoint immunotherapy. In contrast, Cohort B had 25 standard care-related grade 3 adverse events, of which four were immune checkpoint inhibitor-related side effects (three grade 3 and one grade 4).
This represents a 44% reduction in grade 3 or higher adverse events when INT230-6 is combined with immunochemotherapy compared to standard care alone. Lewis H. Bender, Founder, President & CEO, noted that "reducing the total number of grade 3 or higher adverse events by 44%, especially immune-related adverse events, and the potential for a higher pCR rate with INT230-6 prior to SOC, could be life-saving for patients."
Study Modifications and Regulatory Progress
In September 2025, enrollment was paused due to skin irritations observed in Cohort A. In early March 2026, the company submitted a protocol amendment to Swissmedic and the Swiss Ethics Committee to resume enrollment using a lower drug volume per tumor volume ratio and a single injection of INT230-6.
The company's previous presurgical breast cancer (search) study, INVINCIBLE-2, completed in 2023 with 58 women receiving one to three injections of INT230-6 alone, showed that skin issues were rare and surgery was performed without complications.
Clinical Context and Regulatory Pathway
Triple-negative breast cancer (search) affects approximately 11 to 17% of breast cancer (search) patients, representing about 56,000 new cases annually in the US and 420,000 worldwide. TNBC (search) is considered more aggressive with poorer prognosis due to fewer available targeted therapies. Current standard neoadjuvant treatment achieves pCR rates of 50 to 65%, depending on tumor size, with lower rates in larger tumors.
The FDA's Accelerated Approval Program recognizes pCR as an accepted surrogate endpoint for approval in high-risk breast cancer (search), including TNBC (search). Achieving pCR has been shown to reduce disease recurrence risk from 50% to 16% at five years.
INT230-6 Mechanism of Action
INT230-6 is designed for direct intratumoral injection and consists of two anti-cancer agents, cisplatin and vinblastine sulfate, combined with a diffusion and cell penetration enhancer molecule (SHAO) that facilitates drug dispersion throughout tumors. The treatment causes local tumor killing and releases neoantigens specific to the malignancy, leading to immune system engagement and systemic anti-tumor effects without the immunosuppression often associated with systemic chemotherapy.
The company expects to present more detailed results for the seven Cohort A patients at a future oncology conference. The INVINCIBLE-4 study is conducted in collaboration with the Swiss Cancer Institute (search) and Unicancer, the French referent cooperative group in breast cancer (search).