Randomized selection design trial evaluating CD8+-enriched versus unselected tumor-infiltrating lymphocytes for adoptive cell therapy for patients with melanoma

Abstract

Purpose: Adoptive cell therapy (ACT) with autologous tumor-infiltrating lymphocytes (TILs) and high-dose interleukin-2 (IL-2) administered to lymphodepleted patients with melanoma can cause durable tumor regressions. The optimal TIL product for ACT is unknown.

Patients and methods: Patients with metastatic melanoma were prospectively assigned to receive unselected young TILs versus CD8(+)-enriched TILs. All patients received lymphodepleting chemotherapy and high-dose IL-2 therapy and were assessed for response, toxicity, survival, and immunologic end points.

Results: Thirty-four patients received unselected young TILs with a median of 8.0% CD4(+) lymphocytes, and 35 patients received CD8(+)-enriched TILs with a median of 0.3% CD4(+) lymphocytes. One month after TIL infusion, patients who received CD8(+)-enriched TILs had significantly fewer CD4(+) peripheral blood lymphocytes (P = .01). Twelve patients responded to therapy with unselected young TILs (according to Response Evaluation Criteria in Solid Tumors [RECIST]), and seven patients responded to CD8(+)-enriched TILs (35% v 20%; not significant). Retrospective studies showed a significant association between response to treatment and interferon gamma secretion by the infused TILs in response to autologous tumor (P = .04), and in the subgroup of patients who received TILs from subcutaneous tumors, eight of 15 patients receiving unselected young TILs responded but none of eight patients receiving CD8(+)-enriched TILs responded.

Conclusion: A randomized selection design trial was feasible for improving individualized TIL therapy. Since the evidence indicates that CD8(+)-enriched TILs are not more potent therapeutically and they are more laborious to prepare, future studies should focus on unselected young TILs.

Trial registration: ClinicalTrials.gov NCT00513604.

Conflict of interest statement

Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.

Figures

Fig 1.

CONSORT diagram for this randomized selection design protocol. The success rate for patient accrual from tumor resection to protocol enrollment is estimated in the upper portion of the figure, although this represents a retrospective analysis and was not part of the protocol design. Patients were eligible for enrollment onto this protocol when young tumor-infiltrating lymphocytes (TIL) suitable for therapy were determined to be available, and 69 patients were randomly assigned and treated. f/u, follow-up; NED, no evaluable disease.

Fig 2.

Kaplan-Meier survival curve for patients treated in this clinical trial by arm and for a historical control group receiving similar tumor-infiltrating lymphocyte (TIL) therapy. Patients randomly assigned to receive unselected young TILs or CD8+-enriched young TILs are shown, with tick marks indicating patients who are still alive and available for follow-up. Nonmyeloablative lymphodepleting chemotherapy (NMA) TIL represents survival from a historical control group of patients who received TILs selected for tumor reactivity..

Fig 3.

CD8+-enriched tumor-infiltrating lymphocytes (TILs) have an impact on peripheral blood lymphocyte recovery compared with unselected young TILs. (A) The average absolute lymphocyte count of patients on each arm is plotted over time; day 0 is the day of TIL infusion (all patients were not measured every day). Days without symbols represent fewer than 10 patients sampled. SEs of the means are shown by vertical bars. There was no significant difference in absolute lymphocyte count on any day between the randomly assigned arms. The reconstitution of neutrophils, platelets, and RBCs was also not different between the protocol arms (not shown). (B) After therapy, the absolute CD4+ lymphocyte counts in peripheral blood were significantly lower for patients receiving CD8+-enriched TILs than for patients receiving unselected young TILs. Absolute CD4+ counts for patients are shown before the start of lymphodepleting chemotherapy (Pre), at a median of 6 days (1 week) after TIL infusion (range, 5 to 14 days), and at a median of 34 days (1 month) after TIL infusion (range, 23 to 52 days). Data are not available for each patient in each category. The responding patients are jittered slightly to the left of nonresponders (NRs) to illustrate that no difference was observed between responding and nonresponding populations. Median values are indicated by a horizontal bar. Wilcoxon rank sum P values are shown. P value for Pre was not significant.

Fig 4.

Tumor-infiltrating lymphocyte (TIL) release of interferon gamma (IFN-γ) in response to autologous fresh tumor is correlated with response. TILs from the infusion bag of each patient were incubated overnight with enzymatically digested fresh tumor single-cell suspension (46 patients had samples for evaluation). IFN-γ was quantified by enzyme-linked immunosorbent assay and is plotted according to the patient's clinical outcome (objective responder [partial or complete responder] v nonresponder). The median value for each population is plotted as a solid bar. Wilcoxon rank sum P = .038.