ESMO Asia Virtual Congress 2020

Abstract 397P

Background

OBI-833 is a novel cancer vaccine targeting a tumor-associated carbohydrate antigen, Globo H. Results of the dose-escalation trial, which showed a favorable safety profile, supported the following cohort expansion trial in non-small cell lung cancer (NSCLC) patients at a dose of 30 μg.

Methods

Patients with Globo H-positive metastatic NSCLC who have achieved stable disease (SD), or partial response (PR) after at least one regimen of anticancer therapy were enrolled. For patients who were on the targeted therapy, OBI-833 was added to their ongoing therapies. Humoral immune responses and relevant tumor biomarkers were monitored.

Results

A total of 14 patients were successfully enrolled. Treatment is ongoing for five patients. Nine patients have been discontinued. Eleven patients were treated with a 1st or 2nd-generation EGFR TKI and OBI-833, one patient with ceritinib plus OBI-833, and two patients with OBI-833 monotherapy. As of June 2020, a total of 79 treatment-related AEs were reported. Most were injection site reactions. Among the 6 reported SAEs, one was treatment-related, which was Grade 4 acute pancreatitis, and five were non-treatment related. The Globo H expression of the tumor specimens was evaluated by IHC and reported as H score. At the H score cutoffs of 0 and 100, 71% (17/24) and 50% (12/24) of the screened patients were Globo H positive, respectively. Thirteen (93%) and nine (64%) patients showed blood levels of anti-Globo H IgM and IgG. The positivity was defined as the anti-Globo H IgM or IgG concentration ≥ 3 μg/mL at least once during the study period. Median PFS was 31 weeks (range, 3–108). Six of the 11 EGFR TKI-treated patients had SD for over six months. One patient has been treated for more than two years and his treatment is still ongoing. Of note, one patient’s tumor size had reduced by 27% after 16 months of OBI-833 treatment. Plasma EGFR mutation load was significantly reduced from 8.57 to 0 in another patient.

Conclusions

OBI-833 can elicit a beneficial immune response in NSCLC patients and had rendered some TKI-treated patients durable stable disease status. Further development of OBI-833 in EGFR-mutated NSCLC patients to assess the potential benefits of combination therapy of OBI-833 with TKIs is ongoing.

Clinical trial identification

NCT02310464.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

OBI Pharma.

Disclosure

C-C. Ou, C-E. Tsai: Full/Part-time employment: OBI Pharma. P-C. Yang: Advisory/Consultancy: OBI Pharma. All other authors have declared no conflicts of interest.