On June 6, 2016 OncoSec Medical Incorporated ("OncoSec") (NASDAQ: ONCS), a company developing DNA-based intratumoral cancer immunotherapies, reported that its collaborators at the University of California San Francisco (UCSF) presented results at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting, demonstrating the utility of a T-cell exhaustion marker to predict response to anti-PD-1 monotherapies (Press release, OncoSec Medical, JUN 6, 2016, View Source [SID:1234513012]).

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Authors of this poster discussion session from UCSF include Adil Daud, MD, Alain Algazi, MD, and Michael Rosenblum, MD, PhD. This "low-tumor infiltrating lymphocyte" (TIL) marker is currently being used to select patients for the ongoing Phase II investigator-sponsored clinical trial evaluating the combination of OncoSec’s investigational therapy, ImmunoPulse IL-12, and the approved anti-PD-1 therapy, pembrolizumab, in patients with unresectable metastatic melanoma.

Using samples from prior trials, authors presented results from a total of 53 patients evaluable for both response and the T-cell exhaustion marker (TEx). Fifteen patients were treated with a combination of ipilimumab and nivolumab, and 38 with monotherapy anti-PD-1. Patients determined to be "low-TIL" (TEx ≤20%) had 0/12 (0%) responses to anti-PD-1 therapy, while patients who were "high-TIL" (TEx >20%) had 21/26 (81%) responses. Median TEx was 40.3% for responders and 16% for non-responders. Using a threshold of TEx at 20%, the negative predictive value for response was 100% and the positive predictive value was 81%. For patients treated with the combination of ipilimumab and nivolumab, the TEx threshold predictive of response was much lower. The authors concluded that this novel T-cell exhaustion marker (% TEx) is an accurate predictor of response to monotherapy, but not response to combination therapy with ipilimumab and nivolumab.

OncoSec is currently enrolling patients into the Phase II clinical trial led by UCSF to assess the anti-tumor activity, safety, and tolerability of the combination of ImmunoPulse IL-12 and pembrolizumab. This multi-center, open-label, single-arm trial is the first study to select patients for "low-TIL" status using UCSF’s T-cell exhaustion marker assay. The study will test the hypothesis as to whether the addition of ImmunoPulse IL-12 to pembrolizumab can increase the response rate in low-TIL melanoma patients, who have a low likelihood of responding to monotherapy with anti-PD-1 blockade. The key endpoints of the study include: best overall response rate (BORR) by RECIST v1.1 and immune-related Response Criteria (irRC); safety and tolerability; duration of response; 24-week landmark progression-free survival; median progression-free survival; and overall survival.

"We are delighted that our collaborators are presenting data at ASCO (Free ASCO Whitepaper) demonstrating the utility of the flow cytometric TIL assay," said Robert H. Pierce, MD, Chief Scientific Officer at OncoSec. "Our ongoing investigator-sponsored combination trial of ImmunoPulse IL-12 and pembrolizumab hinges on the strong predictive value for poor treatment outcomes from this assay. Given these data, we are confident that we will be able to robustly identify a combination efficacy signal in our ongoing single-arm trial."

For more information about this trial, please visit: View Source