Treatment Response and Outcomes of Prostate Cancer Patients Carrying the Germline MMS22L F722fs Mutation.

[BACKGROUND] Methyl Methanesulfonate-Sensitivity Protein 22-Like (MMS22L) plays a key role in homology-directed DNA repair, and experimental models have shown that its loss confers sensitivity to Poly (ADP-ribose) polymerase inhibitors (PARPi). A rare germline loss-of-function founder mutation in MMS22L, F722fs (c.2164_2168del), was recently identified as a prostate cancer risk factor among individuals of Ashkenazi Jewish ancestry. The impact of this mutation on the disease course following prostate cancer diagnosis remains unclear. Here, we report the longitudinal outcomes of seven MMS22L F722fs carriers diagnosed with different stages of prostate cancer identified at the Brady Urological Institute at Johns Hopkins University.

[METHODS] We investigated the longitudinal outcomes of seven MMS22L F722fs carriers diagnosed with different stages of prostate cancer identified at the Brady Urological Institute.

[RESULTS] With a follow-up time ranging from 5 to 27 years, five of the seven patients who were initially treated with radical prostatectomy remain alive and disease-free, including two patients who had adjuvant and salvage therapies, and one patient who was cured after developing metastatic disease post-surgery. For the remaining two patients with metastatic prostate cancer at diagnosis, one patient responded to ADT for 11 years, and the other died of unknown causes 5 years after diagnosis. None of these patients received PARPi.

[CONCLUSIONS] Although limited by its retrospective design and small cohort size, this series suggests the potential for exceptional outcomes in F722fs mutation carriers diagnosed with prostate cancer, despite the aggressive disease features and lack of treatment with PARPi. The findings also suggest that prostate cancer patients with this mutation may respond well to standard systemic treatments.