Safety and tolerability of MEDI0562 in combination with durvalumab or tremelimumab in patients with advanced solid tumors.

Research Funding: AstraZeneca Background: We report safety and tolerability of MEDI0562, a humanized IgG1κ OX40 monoclonal antibody (mAb), in combination with durvalumab (durva; anti-PD-L1 mAb) or tremelimumab (treme; anti-CTLA-4 mAb) in patients (pts) with previously treated advanced solid tumors.Methods:In this phase 1, open-label study (NCT02705482), adult pts received escalating doses of MEDI0562 (2.25, 7.5 or 22.5 mg/kg) every 2 wks (Q2W) in combination with durva (1500 mg/kg) or treme (75 or 225 mg/kg) Q4W, until confirmed disease progression or unacceptable toxicity. Tumor assessments were performed Q8W with immune-related Response Evaluation Criteria in Solid Tumors.Results:In total, 27 and 31 pts received MEDI0562 + durva or treme, across 5 dose combination cohorts (3 + 3 design), with a maximum tolerated dose of 7.5 mg MEDI0652 + 1500 mg durva and maximum administered dose of 10 mg MEDI0562 + 225 mg treme. Median duration of exposure was 12.0 (range 2.0–80.9) and 8.0 (range 2.0–42.0) wks, respectively. Two (22.5 mg MEDI10562 + durva) and 3 (2.25 mg MEDI0652 + 225 mg treme, 22.5 mg MEDI0562 + 75 and 225 mg treme) dose limiting toxicities were observed. For MEDI0562 + durva and MEDI0562 + treme groups respectively, treatment-emergent adverse events (TEAEs) were reported in 96.3% and 100% of pts; most common TEAEs were fatigue (55.6%) and pruritus (45.2%), Gr 3/4 TEAEs occurred in 74.1% and 67.7%; and MEDI0562-related AEs were reported in 20 (74.1%) and 24 (77.4%) pts. Six TEAEs in each group led to MEDI0562 discontinuation (22.2% and 19.4%, respectively), 2 led to death (renal failure [7.5 mg MEDI0562 + durva], multiple organ dysfunction syndrome [22.5 mg MEDI0562 + 225 mg treme]). Three response evaluable pts had PR (11.5% [7.5 and 22.5 mg MEDI0562 + durva, n = 26]). Median overall survival was 17.4 and 11.9 mos for MEDI0562 + durva and MEDI0562 + treme, with stable disease seen in 9 pts from each group, 34.6% vs 29.0%, respectively. Serum exposure of MEDI0562 increased dose proportionally. Post treatment serum antidrug antibody (ADA) was detected in 20 pts from MEDI0562 + durva and MEDI0562 + treme (74.1% and 71.4%, respectively). The impact of ADA on MEDI0562 pharmacokinetics was seen at all doses. Mean percentage of Ki67+CD4+ and Ki67+CD8+ memory T cells increased, while mean percentage of OX40+CD4+ memory T cells decreased following the first dose of MEDI0562 + durva or treme.Conclusions:The safety profile of MEDI0562 in combination with durva or treme was similar between groups. Clinical activity was observed with MEDI0562 + durva in pts with advanced solid tumors. Clinical trial information: NCT02705482