'Re-Priming' RT After Incomplete Response to CAR-T in R/R NHL

Early clinical trials of CAR-T in R/R NHL suggest that only ~40% of patients achieve CR by day 30 PET/CT evaluation. Of those who do not, the large majority (~70%) ultimately fail, while ~30% convert to CR after a median time of 64 days (range, 49-424). This group of patients, who have incomplete response on day 30 PET/CT after CAR-T and thus are most likely to fail CAR-T alone, may be the ideal target for early therapeutic intervention to 're-prime' CAR-T and convert them from IR to CR.

Preclinical and early clinical studies suggest potential immune augmentation when combining RT with CAR-T. Therefore, we propose a phase I/II clinical trial investigating the impact of RT to poor responding sites of disease after CD19-directed CAR-T in R/R NHL patients who are likely to fail CAR-T alone. We hypothesize that focal RT to residual FDG-avid sites of disease on day 30 PET/CT will improve the number of patients who convert to CR by day 90 PET/CT both through local cytotoxic effects as well as local and systemic synergistic effects through 're-priming' of CAR T-cells.

Inclusion criteria

• Age ≥ 18 years.
• Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 at screening
• Biopsy-proven histological high-grade non-Hodgkin lymphoma, such as diffuse large B-cell lymphoma (DLBCL), primary mediastinal B-cell lymphoma (PMBCL), or transformed follicular lymphoma.
• Prior treatment with any CD19-directed CAR T-cell therapy, such as tisagenlecleucel (tisa-cel, Kymriah), axicabtagene ciloleucel (axi-cel, Yescarta), or lisocabtagene maraleucel (liso-cel).
• Incomplete response noted on day 30 PET post-CAR-T, defined as not achieving CR per Lugano 2014 classification
• Ability to understand and the willingness to sign a written informed consent
• All men, as well as women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.

7.1 A female of child-bearing potential is any woman (regardless of sexual orientation, marital status, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:

• Has not undergone a hysterectomy or bilateral oophorectomy; or
• Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).

Exclusion criteria

• Prior "definitive" radiation therapy (40-50 Gy EQD2 with an α/β of 10) to one or more sites of incomplete response as noted on day 30 post-CAR-T PET/CT scan within the past one year. Prior "palliative" radiation therapy (<40 Gy EQD2) permissible at discretion of treating physician.
• Intracranial site of incomplete response as noted on day 30 post-CAR-T PET/CT scan or any active central nervous system involvement by malignancy.
• Active grade 3 or higher CRS or neurotoxicity related to CAR-T.
• Patients with prior history of auto-immune disease or other contraindication to RT.
• Patients with life expectancy < 3 months.
• Psychiatric illness/social situations that would limit compliance with study requirements.
• Subjects must not be pregnant or nursing due to the potential for congenital abnormalities and the potential of this regimen to harm nursing infants.
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that, in the opinion of the investigator, would limit compliance with study requirements.