Loss of CDK12 as a marker of aggressive disease likely to metastasise, but with higher response rates to checkpoint inhibition

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May 4, 2020

SCIENTIFIC

Two retrospective studies have identified loss of CDK12 as a marker of aggressive disease likely to metastasise, but with higher response rates to checkpoint inhibition. CDK12 mutation is found in ~3% of patients.

CDK12-Altered Prostate Cancer: Clinical Features and Therapeutic Outcomes to Standard Systemic Therapies, Poly (ADP-Ribose) Polymerase Inhibitors, and PD-1 Inhibitors

Emmanuel S. Antonarakis et al ,JCO Precision Oncology no. 4 (2020) 370-381

PURPOSE

In prostate cancer, inactivating CDK12 mutations lead to gene fusion–induced neoantigens and possibly sensitivity to immunotherapy. We aimed to clinically, pathologically, and molecularly characterize CDK12-aberrant prostate cancers.

METHODS

We conducted a retrospective multicenter study to identify patients with advanced prostate cancer who harbored somatic loss-of-function CDK12 mutations. We used descriptive statistics to characterize their clinical features and therapeutic outcomes (prostate-specific antigen [PSA] responses, progression-free survival [PFS]) to various systemic therapies, including sensitivity to poly (ADP-ribose) polymerase and PD-1 inhibitors.

RESULTS

Sixty men with at least monoallelic (51.7% biallelic) CDK12 alterations were identified across nine centers. Median age at diagnosis was 60.5 years; 71.7% and 28.3% were white and nonwhite, respectively; 93.3% had Gleason grade group 4-5; 15.4% had ductal/intraductal histology; 53.3% had metastases at diagnosis; and median PSA was 24.0 ng/mL. Of those who underwent primary androgen deprivation therapy for metastatic hormone-sensitive disease (n = 59), 79.7% had a PSA response, and median PFS was 12.3 months. Of those who received first-line abiraterone and enzalutamide for metastatic castration-resistant prostate cancer (mCRPC; n = 34), 41.2% had a PSA response, and median PFS was 5.3 months. Of those who received a first taxane chemotherapy for mCRPC (n = 22), 31.8% had a PSA response, and median PFS was 3.8 months. Eleven men received a PARP inhibitor (olaparib [n = 10], rucaparib [n = 1]), and none had a PSA response (median PFS, 3.6 months). Nine men received a PD-1 inhibitor as fourth- to sixth-line systemic therapy (pembrolizumab [n = 5], nivolumab [n = 4]); 33.3% had a PSA response, and median PFS was 5.4 months.

CONCLUSION

CDK12-altered prostate cancer is an aggressive subtype with poor outcomes to hormonal and taxane therapies as well as to PARP inhibitors. A proportion of these patients may respond favorably to PD-1 inhibitors, which implicates CDK12 deficiency in immunotherapy sensitivity.

CDK12-Mutated Prostate Cancer: Clinical Outcomes With Standard Therapies and Immune Checkpoint Blockade

Michael T. Schweizer et al CO Precision Oncology no. 4 (2020) 382-392

PURPOSE

Translational studies have shown that CDK12 mutations may delineate an immunoresponsive subgroup of prostate cancer, characterized by high neo-antigen burden. Given that these mutations may define a clinically distinct subgroup, we sought to describe outcomes to standard drugs and checkpoint inhibitors (CPI).

PATIENTS AND METHODS

Clinical data from consecutive patients with CDK12 mutations were retrospectively collected from 7 centers. Several clinical-grade sequencing assays were used to assess CDK12 status. Descriptive statistics included PSA50 response rate (≥ 50% decline in prostate-specific antigen from baseline) and clinical/radiographic progression-free survival (PFS).

RESULTS

Of 52 patients with CDK12-mutated prostate cancer, 27 (52%) had detected biallelic CDK12 alterations. At diagnosis, 44 (88%) had Gleason grade group 4-5, 52% had T3-T4, and 14 (27%) had M1 disease. Median follow-up was 8.2 years (95% CI, 5.6 to 11.1 years), and 49 (94%) developed metastatic disease. Median overall survival from metastasis was 3.9 years (95% CI, 3.2 to 8.1 years). Unconfirmed PSA50 response rates to abiraterone and enzalutamide in the first-line castration-resistant prostate cancer setting were 11 of 17 (65%) and 9 of 12 (75%), respectively. Median PFS on first-line abiraterone and enzalutamide was short, at 8.2 months (95% CI, 6.6 to 12.6 months) and 10.6 months (95% CI, 10.2 months to not reached), respectively. Nineteen patients received CPI therapy. PSA50 responses to CPI were noted in 11%, and PFS was short; however, the estimated 9-month PFS was 23%. PFS was higher in chemotherapy-naïve versus chemotherapy-pretreated patients (median PFS: not reached v 2.1 months, P = .004).

CONCLUSION

CDK12 mutations define an aggressive prostate cancer subgroup, with a high rate of metastases and short overall survival. CPI may be effective in a minority of these patients, and exploratory analysis supports using anti–programmed cell death protein 1 drugs early. Prospective studies testing CPI in this subset of patients with prostate cancer are warranted.