Purpose: The ability to mount lymphoproliferative responses to peptides derived from the human papillomavirus (HPV) E6 and E7 oncoproteins has been associated with regression of dysplastic lesions of the uterine cervix and loss of associated HPV infection. Interleukin-12 (IL-12) is a potent immunopotentiator of T-cell function, and has been shown in phase I clinical trials to be tolerable.
Experimental design: Patients were required to have measurable metastatic, recurrent or inoperable cervical carcinoma. Patients could have had one prior adjuvant regimen and one prior regimen for advanced disease. Treatment consisted of IL-12 administered at 250 ng/kg IV as a rapid push in the outpatient setting daily x 5 every 21 days. Whole blood samples were acquired twice before treatment then approximately every 3 weeks to assess lymphoproliferative response in vitro to HPV type 16 (HPV 16) E4, E6, and E7 peptides. These responses were correlated with demographics and with clinical outcome.
Results: Thirty-four patients were enrolled; 29 were evaluable. Over half had received cisplatin-based chemotherapy. The most common serious toxicities were hematologic or hepatic, and all were reversible. There was one partial responder (3%). The median survival was 6.5 months (95% CI: 5.8, 11.5 months). Eighteen of 29 eligible patients had evaluable laboratory data both pre- and post-therapy. There was a statistically significant increase in lymphoproliferative responses for HPV 16 E4, E6, and E7 peptides (P=0.020, 0.020, 0.043). There was a significant association between change in lymphoproliferative response to HPV 16 E6 peptides and number of cycles of treatment administered (P=0.048). There was no correlation between change in lymphoproliferative response to any peptide with age, performance status, race, prior chemotherapy, time from diagnosis to treatment, or with overall survival.
Conclusions: IL-12 treatment was associated with improved lymphoproliferative responses to HPV 16 E4, E6, and E7 peptides. This is the first clinical trial to demonstrate induction of cell-mediated immune (CMI) responses to specific antigens (peptides) following treatment with IL-12 in women with cervical cancer. This improvement in immune response was not associated with enhanced objective response or survival.