On March 21, 2017 Heat Biologics, Inc. ("Heat") (Nasdaq:HTBX), a leader in the development of immunotherapies designed to activate a patient’s immune system against cancer, reported the latest results of its ongoing Phase 2 clinical trial of HS-110 in combination with Bristol-Myers Squibb’s anti-PD-1 checkpoint inhibitor, nivolumab (Opdivo), for the treatment of non-small cell lung cancer (NSCLC) (Press release, Heat Biologics, MAR 21, 2017, View Source [SID1234518225]). Fifteen patients have completed the HS-110/nivolumab combination treatment to-date and 12 of these 15 patients were evaluable for ELISPOT analysis. Researchers reported a strong correlation between T cell activation, tumor reductions and increased overall survival in these 12 patients. These data reinforce preliminary results seen in the first eight patients as reported last December at the International Association for the Study of Lung Cancer Annual Meeting.

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Key findings:

Immune responses to HS-110 were observed in all 5 patients that exhibited tumor reductions.

No tumor reductions were observed in patients that did not mount an immune response to HS-110.

The timing of immune responses to HS-110 corresponded to the timing of observed clinical responses, and those responses appear to be sustained.

To-date, 5 patients have been enrolled in the low tumor infiltrating lymphocytes (TIL) cohort (patients with "cold" tumors). Three of these 5 patients (60%) have experienced significant tumor reduction, which is higher than the 10% response rate of low TIL patients reported for existing data on nivolumab alone.1
Researchers reported continued indications that patients are mounting a vaccine-mediated immune response to the vaccine lysate, as well as to peptides derived from cancer-specific antigens in their peripheral blood cells via ELISPOT analysis. ELISPOT analysis is the most widely used method for monitoring cellular immune responses in humans. This suggests that the HS-110 vaccine is making a measurable contribution to the desired cancer-specific immune response.

Of the 15 patients who have completed the HS-110/nivolumab combination treatment to-date, 12 were evaluable for ELISPOT analysis. Six of the 12 evaluable patients met the criteria for a positive ELISPOT response to vaccine lysate, and 5 of these 6 patients experienced tumor reductions and increased overall survival. All 5 patients who exhibited a clinical response also saw an immune response to HS-110. Of the 6 patients who did not respond by ELISPOT analysis, 5 patients saw tumor progression and 1 patient discontinued treatment due to a non-serious adverse event.

These data suggest that the 5 tumor reductions seen thus far in the 15 evaluated patients are the result of synergistic activity between HS-110 and anti-PD-1 therapy. Researchers also reported that the safety profile continues to be favorable in the HS-110/nivolumab combination, with no evidence of additional toxicities seen as compared to existing data on nivolumab alone.

"Checkpoint inhibitors, such as nivolumab, are currently effective in treating approximately 10% of lung cancer patients with low TIL and about 20% of patients overall in the 2nd line setting," said Jeff Hutchins, Ph.D., Heat’s Chief Scientific Officer and Senior Vice President of Preclinical Development. "Our results appear to further validate the expected mechanism of action of our approach in combination with checkpoint inhibitors, with a continuing trend towards early and sustained T cell activation in the peripheral blood cells. All patients who mounted a sustained immune response to HS-110 exhibited substantial tumor reductions. We do not see any tumor reduction in patients who did not mount a response to the vaccine. Furthermore, if ELISPOT assay results continue to correlate with clinical results, the combination of HS-110 and nivolumab may become an attractive therapeutic approach for the approximately 80% of patients that do not respond well to nivolumab alone, particularly with the positive safety profile of this combination seen to-date."

1Teng et al, Cancer Research 75(11) June 1, 2015