IMX-110 Plus Tislelizumab Leads to Tumor Shrinkage in Heavily Pretreated mCRC

Treatment with the combination of the tissue-specific therapeutic IMX-110 and the anti–PD-1 antibody tislelizumab (BGB-A317) led to tumor shrinkage in heavily pretreated patients with metastatic colorectal cancer (mCRC), according to data from a second interim update from the ongoing phase 1b/2a IMMINENT-01 trial (NCT05840835).¹

Among 4 evaluable patients, 3 (75%) experienced tumor shrinkage at 2 months. Additionally, 1 patient (25%) achieved tumor control at 2 months, and 1 patient remained on treatment as of the July 7, 2023, data cutoff. The median progression-free survival (PFS) and overall survival (OS) were not yet reached.

Notably, these patients received a median of 8 prior lines of therapy, and all 4 patients had mismatch repair–proficient relapsed/refractory mCRC.

No dose-limiting toxicities have been observed in the first 2 cohorts, and the study is now enrolling the next cohort of patients (n = 3) at a higher dose of IMX-110 in combination with tislelizumab.

“We are encouraged that in these early cohorts of patients receiving just a fraction of what we believe will be the optimal dose, we continue to see signals of activity of IMX-110 in [patients with] relapsed/refractory mCRC [who] received a median of 8 lines of anticancer therapies that failed to halt cancer growth prior to receiving IMX-110 plus tislelizumab,” Ilya Rachman, MD, PhD, chief executive officer of Immix Biopharma, stated in a news release. “In the subsequent higher dose cohorts of IMMINENT-01, we are hopeful that clinical results will further improve. The optimal dose identified in IMMINENT-01 will be utilized in our upcoming phase 2 IMMINENT-02 clinical trial.”

Data reported in a prior interim analysis demonstrated that 100% tumor shrinkage at 2 months was observed in 2 evaluable patients with advanced mCRC who were treated at the lowest dose level of IMX-110 examined in the dose-escalation portion of the study.²

IMMINENT-01 is an ongoing, single-arm, dose-escalation and -expansion study enrolling patients at least 16 years of age with histologically confirmed advanced solid tumors who have progressed, are refractory, or are intolerant to standard therapy appropriate for their respective tumor type.³ Other key inclusion criteria include an ECOG performance status of 0 to 2, a life expectancy of at least 3 months, and adequate cardiac function as measured by a left ventricular ejection fraction of more than 50%.

Key exclusion criteria include any chemotherapy within 14 days of dosing, immunotherapy within 28 days of treatment, or biologic or hormonal therapy within 28 days of dosing, although patients with prostate cancer can continue to receive administration of GnRH agonists; treatment with any other study drug within 4 weeks, or investigational immunotherapy within 6 weeks; or patients who are expected to need surgery or benefit from other anticancer therapy during the study.

Escalating doses of IMX-110 are being administered in combination with tislelizumab during the dose-escalation portion of the study. The recommended phase 2 dose (RP2D) will be evaluated in dose expansion, and phase 2a will then be submitted as an amendment to the phase 1 protocol.

Establishing the maximum tolerated dose and the RP2D, as well as incidence of treatment-related adverse effects, are the trial’s primary end points. Secondary end points include overall response rate, PFS, OS, duration of response, and plasma concentrations of IMX-110.

The FDA granted orphan drug designation to IMX-110 for the treatment of patients with soft tissue sarcoma in September 2021.⁴

References

1. Immix Biopharma reports 2nd positive interim clinical trial data readout in relapsed/refractory metastatic colorectal cancer in ongoing phase 1b/2a IMX-110 IMMINENT-01 clinical trial. News release. July 17, 2023. Accessed July 18, 2023. https://immixbio.com/2023/07/17/immix-biopharma-reports-2nd-positive-interim-clinical-trial-data
2. Immix Biopharma announces early positive IMX-110 interim clinical trial data demonstrating 100% tumor shrinkage in advanced metastatic colorectal cancer at the lowest dose of IMX-110 + BeiGene anti-PD-1 antibody tislelizumab. News release. Immix Biopharma, Inc. May 3, 2023. Accessed July 18, 2023. https://immixbio.com/2023/05/03/
3. Study of IMX-110 in combination with tislelizumab in patients with advanced solid tumors (IMMINENT-01). ClinicalTrials.gov. Updated May 6, 2023. Accessed July 18, 2023. https://clinicaltrials.gov/ct2/show/NCT05840835
4. ImmixBio announces FDA orphan drug designation for IMX-110 for the treatment of soft tissue sarcoma. News release. Immix Biopharma, Inc. September 30, 2021. Accessed July 18, 2023. https://www.prnewswire.com/news-releases/immixbio-announces-fda-orphan-drug-designation