Preclinical Characterization and Phase I Trial Results of INBRX-109, A Third-Generation, Recombinant, Humanized, Death Receptor 5 Agonist Antibody, in Chondrosarcoma

PURPOSE

Patients with unresectable/metastatic chondrosarcoma have poor prognoses; conventional chondrosarcoma is associated with a median progression-free survival (PFS) of <4 months after first-line chemotherapy. No standard targeted therapies are available. We present the preclinical characterization of INBRX-109, a third-generation death receptor 5 (DR5) agonist, and clinical findings from a phase I trial of INBRX-109 in unresectable/metastatic chondrosarcoma (NCT03715933).

PATIENTS AND METHODS

INBRX-109 was first characterized preclinically as a DR5 agonist, with binding specificity and hepatotoxicity evaluated in vitro and antitumor activity evaluated both in vitro and in vivo. INBRX-109 (3 mg/kg every 3 weeks) was then evaluated in a phase I study of solid tumors, which included a cohort with any subtype of chondrosarcoma and a cohort with IDH1/IDH2-mutant conventional chondrosarcoma. The primary endpoint was safety. Efficacy was an exploratory endpoint, with measures including objective response, disease control rate, and PFS.

RESULTS

In preclinical studies, INBRX-109 led to antitumor activity in vitro and in patient-derived xenograft models, with minimal hepatotoxicity. In the phase I study, INBRX-109 was well tolerated and demonstrated antitumor activity in unresectable/metastatic chondrosarcoma. INBRX-109 led to a disease control rate of 87.1% [27/31; durable clinical benefit, 40.7% (11/27)], including two partial responses, and median PFS of 7.6 months. Most treatment-related adverse events, including liver-related events, were low grade (grade ≥3 events in chondrosarcoma cohorts, 5.7%).

CONCLUSIONS

INBRX-109 demonstrated encouraging antitumor activity with a favorable safety profile in patients with unresectable/metastatic chondrosarcoma. A randomized, placebo-controlled, phase II trial (ChonDRAgon, NCT04950075) will further evaluate INBRX-109 in conventional chondrosarcoma.

Abstract 2912: INBRX-130, a 5T4-targeted CONTRA-MAB, is a potent CD3 bispecific antibody engineered to have minimal off-tumor activity

Bispecific T cell engagers that target CD3 on T cells and cell-surface antigens on tumor cells have demonstrated meaningful clinical activity against hematological cancers but have yet to achieve similar efficacy for the treatment of solid tumors. A variety of factors may be contributing to this lack of success in the solid tumor setting, including insufficient exposure of tumor cells to these targeted therapeutics due to target-independent interactions with peripheral T cells. Not only can circulating cells act as a sink for CD3 bispecifics but these interactions can lead to cytokine release syndrome (CRS), a common and dose-limiting toxicity for this class of therapeutics. We have developed a CD3 bispecific platform, CONTRA-MAB® (Constrained T Cell Redirecting and Activating Multispecific Antibody), that combines high-affinity tumor-associated antigen binding single-domain antibodies (sdAbs) with a constrained CD3-targeting VH/VL pair that has been strategically positioned and affinity engineered to minimize T cell activation and cytokine production in the absence of target antigen engagement. INBRX-130 is a CONTRA-MAB® that targets trophoblast glycoprotein (TPBG; 5T4), a cell-surface protein that is upregulated across many solid tumor indications but has restricted expression on normal adult tissues. As determined by flow cytometry, INBRX-130 exhibits specific and high-affinity binding to 5T4-positive cells but shows no detectable binding to T cells, absent target, at concentrations up to one micromolar. Additionally, treatment of peripheral blood mononuclear cells (PBMCs) with high concentration INBRX-130 does not result in production of detectable levels of CRS-associated inflammatory cytokines. Upon binding to 5T4-expressing tumor cells in vitro, INBRX-130 potently induces T cell activation, proliferation, cytokine production, and cytotoxicity, resulting in target cell death. INBRX-130 has favorable pharmacokinetic properties and the capacity to effect regression of 5T4+ tumors in humanized mice, even in models that display minimal initial T-cell infiltrate. INBRX-130 is well-tolerated by cynomolgus monkeys at the maximally administered dose of 2 mg/kg without the requirement of a priming dose. Preliminary in vitro data with CONTRA-MABs® targeting other solid tumor antigens supports the broad applicability of this unique T cell engager platform. CONTRA-MABs® have the potential to have enhanced accumulation in solid tumors relative to other CD3 bispecific antibodies as a result of reduced systemic engagement of T cells and increased tolerability at high doses. These attributes, coupled with the broad tumor biased expression of 5T4 across solid tumors, may enable INBRX-130 to have a greater therapeutic index and provide a significant benefit to patients in need.

Citation Format: Katelyn M. Willis, Margaret Haerr, Marchelle Meza, Sae Jeong Ahn, Michael Kaplan, Georgina Ortiz-Barquero, Rajay Pandit, Rafael Abalos, Yao Chen, Samuel Holley, Raul Lozano, Iljin Hwang, Emily Rowell, Brendan P. Eckelman. INBRX-130, a 5T4-targeted CONTRA-MAB, is a potent CD3 bispecific antibody engineered to have minimal off-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2912.

Is follow-up of lung cancer patients after resection medically indicated and cost-effective?

BACKGROUND

There are no guidelines for the appropriate follow-up of patients after pulmonary resection for lung cancer.

METHODS

Three-hundred fifty-eight consecutive patients who had undergone complete resections of non-small cell lung cancer between 1987 and 1991 were evaluated for tumor recurrence and development of second primary tumors. Recurrences were categorized by site (local or distant), mode of presentation (symptomatic or asymptomatic), treatment given (curative intent or palliative), and duration of overall survival.

RESULTS

Recurrences developed in 135 patients (local only, 32; local and distant, 13; and distant only, 90). Of these, 102 were symptomatic and 33 were asymptomatic (most diagnosed by screening chest roentgenogram). Forty patients received treatment with curative intent (operation or radiation therapy > 50 Gy) and 95 were treated palliatively. The median survival duration from time of recurrence was 8.0 months for symptomatic patients and 16.6 months for asymptomatic patients (p = 0.008). Multivariate analysis shows that disease-free interval (greater than 12 months or less than or equal to 12 months) was the most important variable in predicting survival after recurrence and that mode of presentation, site of recurrence, initial stage, and histologic type did not significantly affect survival. New primary tumors developed in 35 patients.

CONCLUSIONS

Although detection of asymptomatic recurrences gives a lead time bias of 8 to 10 months, mode of treatment and overall survival duration are not greatly affected by this earlier detection. Disease-free interval appears to be the most important determinant of survival. Screening for asymptomatic recurrences in patients who have had lung cancer is unlikely to be cost-effective. Frequent follow-up and extensive radiologic evaluation of patients after operation for lung cancer are probably unnecessary.

Resection of lung cancer is justified in high-risk patients selected by exercise oxygen consumption

The medical criteria for inoperability have been difficult to define in patients with lung cancer. Sixty-six patients with non-small cell lung cancer and radiographically resectable lesions were evaluated prospectively in a clinical trial. The patients were considered by cardiac or pulmonary criteria to be high risk for pulmonary resection. If exercise testing revealed a peak oxygen uptake of 15 mL.kg-1.min-1 or greater, the patient was offered surgical treatment. Of the 20 procedures performed, nine were lobectomies, two were bilobectomies, and nine were wedge or segmental resections. All patients were extubated within 24 hours and discharged within 22 days after operation (median time to discharge, 8 days). There were no deaths, and complications occurred in 8 (40%) of the 20 patients. Five patients whose peak oxygen uptake was lower than 15 mL.kg-1.min-1 also underwent surgical intervention; there was one death. Thirty-four patients whose peak oxygen uptake was less than 15 mL.kg-1.min-1 and 7 who declined operation underwent radiation therapy alone (35 patients) or radiation therapy and chemotherapy (6 patients). There were no treatment-related deaths, and the morbidity rate was 12% (5/41). The median duration of survival was 48 +/- 4.3 months for the patients treated surgically and 17 +/- 2.7 months for those treated medically (p = 0.0014). We conclude that a subgroup of patients who would be considered to have inoperable disease by traditional medical criteria can be selected for operation on the basis of oxygen consumption exercise testing. There is a striking survival benefit to an aggressive surgical approach in these patients.

Evidence for less improvement in depression in patients taking benzodiazepines during unilateral ECT

Among 48 patients with diagnoses of depression according to DSM-III, there was a significant relation between therapeutic failure of unilateral ECT, as measured by scores on the Hamilton Rating Scale for Depression, and the concomitant use of a benzodiazepine. Of the 34 patients who showed a good therapeutic response to unilateral ECT, those taking benzodiazepines had smaller changes in their Hamilton depression ratings from before treatment to after treatment and were more symptomatic at the end of the course of ECT. Thus, when patients take benzodiazepines during a course of unilateral ECT, the maximum therapeutic response may be compromised.