Fifteen out of 20 planned patients with antihistamine refractory CIndU have received a single intravenous infusion of CDX-0159 at 3 mg/kg, including nine patients with cold contact urticaria (ColdU) and six patients with symptomatic dermographism (SD). Safety results are reported for all 15 patients; activity results are reported for all patients assessed for at least 15 days/2 weeks after treatment (n=10; 7 ColdU and 3 SD). Patients had high disease activity as assessed by provocation threshold testing. In ColdU and SD pts, baseline critical temperature thresholds were 18.7 +/- 2.7 °C (range: 5-27°C) and FricTest® thresholds were 3.7 +/- 0.3 (range: 3-4) of 4.
- Eight of 10 patients (7 ColdU; 1 SD) experienced a complete response (CR) as assessed by provocation threshold testing through their latest assessment. The remaining two patients (both with SD) were recently treated and have been followed for two weeks. One patient experienced a partial response (PR) thus far, and one patient has reported symptomatic improvement (decreased itching). All patients will continue to be assessed for response through week 12.
- Patient global assessment (Pat-GA) and physician global assessment (Phy-GA) results are consistent with provocation testing results.
- Measurements of serum tryptase levels are available for only the first six patients evaluated for activity, all with ColdU. The mean baseline was 3.3 +/- 0.2 ng/ml and levels on day 15 after treatment were at or below the limit of detection. These patients all experienced complete responses.
- CDX-0159 was generally well tolerated. Six of 15 patients had mild infusion reactions, generally areas of localized redness and itching, which resolved rapidly. A single severe infusion reaction was observed (brief loss of consciousness, followed by shaking and sweating). The patient was treated with antihistamines and steroids; no epinephrine was administered. The patient rapidly recovered and was hospitalized for observation with no further manifestations of this event. Importantly, there was no evidence of mast cell activation as measured by decreases in serum tryptase levels shortly after the infusion and further at a later time point.
- Through day 15, three patients had transient, mild decreases in hemoglobin, and no patients had meaningful declines in white blood cells.
