The Study Safety Committee has recommended that the trial proceed to enroll patients in the highest-dose cohort.
SQZ-AAC-HPV, SQZ Biotech’s autologous red blood cell therapy, has yielded a complete response (CR) in the first patient with HPV16+ solid tumors treated in the low-dose cohort of SQZ-AAC-HPV-101 (ENVOY-001) phase 1 clinical trial (NCT04892043).1
“Although early in this trial, we have observed good tolerability among the patients. The confirmed complete response observed in this patient demonstrates the potential of the investigational therapy’s intended immunotherapy mechanism,” Richard T. Maziarz, MD, Professor of Medicine and Investigator, Oregon Health & Science University, said in a statement.1
The trial has also enrolled the second and third patients in the low dose cohort and has completed the dose-limiting toxicity period in this cohort. The Study Safety Committee has reviewed the findings seen so far and has recommended that the company proceed toenroll patients in the highest-dose cohort. Initial clinical data from this cohort is expected by the fourth quarter of 2023.
The patient with the CR is a 61-year-old male with a history of metastatic HPV16+ rectal squamous cell carcinoma. He had 2 prior lines of treatment; these did not include immune checkpoint inhibitors. The patient continues to be monitored in the study and has tolerated SQZ-AAC-HPV well.
The patient had a partial response in December 2022 after 2 cycles of SQZ-AAC-HPV; this response deepened in February 2023 after 4 cycles of SQZ-AAC-HPV to a confirmed partial response. The patient then achieved a CR in March 2023 after 7 cycles of the therapy, as confirmed by CT scan.
“We are motivated by the clinical response in our first patient in the AAC trial,” Marshelle Smith Warren, MD, Chief Medical Officer, SQZ Biotechnologies, added to the statement.1 “We find it encouraging that the confirmed CR occurred in our lowest-dose cohort. It is still early days, but we are optimistic as we look to enroll additional patients and anticipate initial data from the highest-dose cohort in the fourth quarter of this year.”
The SQZ-AAC-HPV therapy is engineered with SQZ’s Cell Squeeze technology to target E6 and E7 oncoproteins, and it consists of Activating Antigen Carriers (AAC) derived from red blood cells (RBCs). The therapy is being studied as a monotherapy and in combination with immune checkpoint inhibitors. The ENVOY-001 study consists of 2 parts, the first of which aims to assess the safety and tolerability of 3 doses of SQZ-AAC-HPV as a monotherapy in patients with HPV+ solid tumors refractory to at least 1 prior line of therapy. The second part will assess safety and tolerability of the therapy in combination with nivolumab and/or ipilimumab.
Primary outcome measures include the incidence of treatment-emergent adverse events and dose-limiting toxicities with SQZ-AAC-HPV monotherapy and combination therapy. Secondary outcome measures include progression free survival, overall survival, objective response rate, duration of response, best overall response, disease control rate, and manufacturing feasibility by batch yield and manufacturing failures.
SQZ has additional candidates in its pipeline targeting HPV16+ solid tumors. One of these is SQZ-eAPC-HPV, based on the company’s second-generation Enhanced Antigen Presenting Cell (eAPC) platform, which received fast track designation by the FDA in December 2022.2 The therapy has demonstrated safety and promising efficacy signals in the phase 1/2 COMMANDER-001 clinical trial (NCT05357898).