TAK-676 in combination with pembrolizumab after radiation therapy in patients (pts) with advanced non–small cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), or squamous-cell carcinoma of the head and neck (SCCHN): Phase 1 study design.

TPS2698 Background: The cyclic GMP-AMP Synthase (cGAS)–STimulator of INterferon Genes (STING) pathway is an important modulator of the innate immune system via induction of type I interferon (IFN-I). Cytosolic DNA generated as a result of tumor cell death following radiation therapy has been demonstrated to activate the cGAS-STING signaling axis resulting in antitumor immunogenicity. TAK-676 is a novel, synthetic STING agonist and it has been shown in preclinical studies to potently modulate the innate immune system and subsequently activate the adaptive immune system to produce antitumor responses. TAK-676 is designed for prolonged half-life in serum and enhanced tissue permeability compared with other STING agonists designed for intratumoral injection, allowing for systemic IV delivery with access to tumor sites and lymphatic tissue. IFN signaling impairment has been linked to checkpoint inhibitor (CPI) resistance in tumors. Treatment with TAK-676 after radiation therapy has the potential to stimulate T cell-mediated antitumor immunity via STING-mediated IFN-I release, particularly when used with anti-PD-1/PD-L1 therapies. Preclinical data support the addition of STING agonists to reverse resistance in tumors with prior exposure to CPIs. TAK-676 is being investigated (+/- pembrolizumab) in an ongoing first-in-human phase 1 study (NCT04420884). Here, we describe another phase 1 trial to investigate the safety and preliminary antitumor activity of TAK-676 plus pembrolizumab following radiation therapy in pts with advanced or metastatic NSCLC, TNBC, or SCCHN (NCT04879849). Methods: Adult pts with progressive disease (PD) following CPI treatment and who have ≥2 lesions, 1 of which can be targeted with radiation, are being enrolled. Pts receive 8 Gy x 3 fractions of image-guided radiation followed (after ≥40 hours) by IV pembrolizumab 200 mg on day 1 plus escalating doses of IV TAK-676 on days 1, 8, and 15 of a 21-day cycle. TAK-676 dose escalation is guided by the Bayesian optimal interval design. Pts receive TAK-676 plus pembrolizumab until PD, intolerance to treatment, or withdrawal. Pts enrolled at TAK-676 dose levels shown to have pharmacodynamic activity, and who have a safely accessible lesion outside the radiation field, will have paired biopsies collected at screening and between days 15 and 21 of cycle 1. The primary objective is to determine the safety and tolerability of TAK-676 plus pembrolizumab following radiation therapy; secondary objectives are to establish the recommended phase 2 dose of TAK-676 plus pembrolizumab following radiation therapy, and to assess preliminary antitumor activity both locally (within the radiation field) and systemically (non-radiated lesions). As of February 2022, we have enrolled ̃10% of the planned pts. Clinical trial information: NCT04879849.