Results of a first-in-human phase I study of SRF231, a fully human, high-affinity anti-CD47 antibody

3064

Background: CD47 is a transmembrane protein that acts as a “Don’t Eat Me” signal to evade immune recognition. It is overexpressed in multiple cancer subtypes and is associated with poor prognosis. SRF231 is an investigational, fully human, high-affinity CD47-targeting antibody that delivers an activating signal to myeloid cells and displays favorable preclinical characteristics regarding its receptor occupancy/tumor exposure/efficacy relationship. Methods: In a Phase 1 study, SRF231-101 (NCT03512340), patients with advanced solid and hematologic malignancies who had failed standard therapy were enrolled in dose escalation cohorts (accelerated single-patient followed by standard 3+3) to establish the preliminary safety of SRF231 as a monotherapy and identify a dose and schedule suitable for expansion. In addition to collection of safety data, clinical outcomes were evaluated based on Response Evaluation Criteria in Solid Tumors (RECIST v1.1) and SRF231 pharmacokinetic (PK) and pharmacodynamic (receptor occupancy) analyses were performed. Results: As of January 11, 2020, a total of 46 patients were enrolled, 25 in every-3-week intravenous (IV) dosing schedules and 21 in weekly IV dosing schedules. Weekly dosing schedules also explored the use of a 1.0 mg/kg initiation dose. Other than one patient with recurrent follicular lymphoma, all patients had recurrent/refractory solid tumors. The most common treatment emergent adverse events across dosing schedules were low-grade fatigue (43%), headache (35%), and pyrexia (30%). On every-3-week dosing schedules, 2 dose-limiting toxicities (DLTs) were observed: Grade 3 febrile neutropenia and Grade 3 hemolysis, both at a 12.0 mg/kg dose level. On weekly dosing schedules, 3 DLTs were observed: Grade 4 thrombocytopenia (6.0 mg/kg), Grade 4 amylase and lipase increased (4.0 mg/kg with initiation dose), and Grade 3 fatigue (4.0 mg/kg). The maximum tolerated dose was 9.0 mg/kg on an every-3-week and 4.0 mg/kg on a weekly schedule. Receptor occupancy was maintained at > 90% throughout the dosing period with a 4.0 mg/kg weekly dose schedule. Out of 37 patients who were response evaluable by RECIST, there were no complete or partial responders, although prolonged stable disease has been observed. Conclusions: Preliminary data from a Phase 1 study of SRF231, an anti-CD47 antibody, demonstrate that SRF231 may be administered safely and doses of 4.0 mg/kg weekly maintain > 90% receptor occupancy throughout the dosing period. Updated safety data, clinical outcomes, and PK/pharmacodynamic data will be presented. Clinical trial information: NCT03512340 .

A Phase I study of an intravesically administered immunotoxin targeting EpCAM for the treatment of nonmuscle-invasive bladder cancer in BCGrefractory and BCG-intolerant patients

PURPOSE

A Phase I dose-escalation study was performed to determine the maximum tolerated dose (MTD) of the immunotoxin VB4-845 in patients with nonmuscle-invasive bladder cancer (NMIBC) refractory to or intolerant of bacillus Calmette-Guerin (BCG). Secondary objectives included evaluation of the safety, tolerability, pharmacokinetics, immunogenicity, and efficacy of VB4-845.

PATIENTS AND METHODS

Sixty-four patients with Grade 2 or 3, stage Ta or T1 transitional cell carcinoma or in situ carcinoma, either refractory to or intolerant of BCG therapy, were enrolled. Treatment was administered in ascending dose cohorts ranging from 0.1 to 30.16 mg. After receiving weekly instillations of VB4-845 to the bladder via catheter for 6 consecutive weeks, patients were followed for 4-6 weeks post-therapy and assessed at week 12.

RESULTS

An MTD was not determined, as a dose-limiting toxicity was not identified over the dose range tested. VB4-845 therapy was safe and well tolerated with most adverse events reported as mild; as a result, no patients were removed from the study in response to toxicity. By the end of the study, the majority of patients had developed antibodies to the exotoxin portion of VB4-845. A complete response was achieved in 39% of patients at the 12-week time point.

CONCLUSIONS

VB4-845 dosed on a weekly basis for 6 weeks was very well tolerated at all dose levels. Although an MTD was not determined at the doses administered, VB4-845 showed evidence of an antitumor effect that warrants further clinical investigation for the treatment of NMIBC in this patient population.

A phase III randomized controlled study comparing iron sucrose intravenously (IV) to no iron treatment of anemia in cancer patients undergoing chemotherapy and erythropoietin stimulating agent (ESA) therapy

9109

Background: The effect of using IV iron sucrose in managing cancer chemotherapy-related anemia has not been previously reported. To investigate this issue, we conducted a randomized study of IV iron sucrose in patients (pts) with cancer chemotherapy-related anemia who completed 8 prior wks of ESA therapy. Methods: This prospective, multicenter, randomized, open label, Phase III clinical trial enrolled 375 pts with chemotherapy induced anemia (Hgb levels = 10.0 g/dL) and was conducted in 2 stages. During Stage I (8-wk duration), pts received treatment with fixed ESA doses (100-mcg of darbepoetin or 40,000 units epoetin wkly or 200 mcg of darbepoetin every other wk). Pts were classified as either ESA responders (= 1 g/dL increase in Hgb) or ESA non-responders with each group randomized (Stage 2) separately to receive either 12 wks of fixed doses of ESA plus up to 1,500 mg of iron sucrose (given in 3 divided doses of up to 500mg) or 12 wks of fixed doses of ESA alone. Laboratories (including iron indices and acute phase reactants), quality of life and adverse events were assessed at baseline and throughout. Results: Iron sucrose plus ESA compared to ESA alone resulted in greater mean maximum Hgb levels and greater number of pts who achieved Hgb increases = 2.0 and ≥ 3.0 g/dl in both prior ESA responders and non-responders. There was also a statistically significant improvement in fatigue and iron stores in the iron sucrose treated pts. Baseline iron status did not predict responsiveness to iron sucrose therapy. Three serious but non-life threatening iron sucrose related adverse events were observed including one case of significant, transient hypotension in a female weighing 50 kg. Conclusions: IV iron sucrose increased Hgb levels and iron stores significantly and is well tolerated in doses up to 500 mg increments in ESA treated patients with cancer chemotherapy- related anemia. IV iron sucrose should be considered in combination with erythropoietic therapy in anemic cancer patients receiving chemotherapy.

[Table: see text]