Health Canada approved Lynparza (olaparib), for the treatment of adult patients with deleterious or suspected deleterious germline and/or somatic BRCA or ATM-mutated metastatic castration-resistant prostate cancer (mCRPC) who have progressed following prior treatment with a new hormonal agent (NHA).

Olaparib is a treatment option for patients with mCRPC and a pathogenic mutaion (germline /somatic) in a homologous recombination repair gene (BRCA1, BRCA2, ATM, BADR1, BRIP1, CDK12, CHEK1, CHEK2, FANCL, PALB2, RAD51B, RAD51C, RAD51D or RAD54L) who have been treated with androgen-receptor therapy.

….139 (76.8%) yielded a result and BRCA/ATM alterations were identified in 111 (79.9%). Of these, 73 patients received olaparib and 38 received control….rPFS was longer in the olaparib group versus control [median 7.4 vs. 3.5 months; hazard ratio (HR), 0.33; 95% confidence interval (CI), 0.21–0.53; nominal P < 0.0001], which is consistent with Cohort A ITT population (HR, 0.34; 95% CI, 0.25–0.47).

At data cut-off (20 March 2020), median final OS in Cohort A was significantly longer with olaparib than with physician’s choice of enzalutamide or abiraterone (HR 0.69; 95% CI 0.50, 0.97; P=0.0175),...Despite extensive crossover from the control arm, olaparib conferred a statistically significant and clinically meaningful prolongation of OS vs sequential therapy with enzalutamide or abiraterone in men with mCRPC with progression on prior therapy and alterations in BRCA1, BRCA2 or ATM, with a 31% reduction in the risk for death.

Cohort A included 245 patients with at least one alteration in BRCA1, BRCA2, or ATM,...The median duration of overall survival in cohort A was 19.1 months with olaparib and 14.7 months with control therapy (hazard ratio for death, 0.69; 95% confidence interval [CI], 0.50 to 0.97; P=0.02)....Among men with metastatic castration-resistant prostate cancer who had tumors with at least one alteration in BRCA1, BRCA2, or ATM and whose disease had progressed during previous treatment with a next-generation hormonal agent, those who were initially assigned to receive olaparib had a significantly longer duration of overall survival than those who were assigned to receive enzalutamide or abiraterone plus prednisone as the control therapy, despite substantial crossover from control therapy to olaparib.

Cohort A (245 patients) had at least one alteration in BRCA1, BRCA2, or ATM...In cohort A, imaging-based progression-free survival was significantly longer in the olaparib group than in the control group (median, 7.4 months vs. 3.6 months; hazard ratio for progression or death, 0.34; 95% confidence interval, 0.25 to 0.47; P<0.001)...

Subgroup analyses of rPFS and overall survival (OS) favored ola vs pcNHA irrespective of prior taxane in Cohort A, Cohorts A+B and pts with a BRCA1 and/or BRCA2 or CDK12 alteration (Table). In the ATM subgroup hazard ratio (HR) point estimates for rPFS and OS were lower in pts who had received prior taxane vs pts who had not, but 95% CIs overlapped and pt numbers were small so data should be interpreted with caution.

AstraZeneca today announced that the US Food and Drug Administration (FDA) has granted Breakthrough Therapy designation (BTD) for the oral poly ADP-ribose polymerase (PARP) inhibitor Lynparza (olaparib), for the monotherapy treatment of BRCA1/2 or ATM gene mutated metastatic Castration Resistant Prostate Cancer (mCRPC)...

...pts with alterations in BRCA1, BRCA2 or ATM...Pts were randomized (2:1) to ola (300 mg bid)...pts with mCRPC and HRR alterations with prior NHA treatment, ola improved rPFS and ORR vs pcNHA, with a favorable trend for OS despite crossover. Safety was generally consistent with the known profile of ola.

...somatic BRCA mutation, Fanconi anemia gene, ATM or RAD51 mutations)...

...- The presence of homologous recombination deficiency defined by either; A) Inherited pathogenic variant of BRCA2, ATM, BRCA1, PALB2 by a Clinical Laboratory Improvement Act (CLIA) level germline assay or B) have evidence by somatic sequencing using a CLIA level assay of biallelic inactivation of BRCA1, BRCA2, PALB2, FANCA or biallelic inactivation or monoallelic inactivating mutation of ATM....

...For enrichment stage of trial only (if necessary): Confirmation of a suspected/known deleterious mutation in a gene of interest (ATM, BARD1, BRCA1, BRCA2, BRIP1, CDK12, CHEK1, CHEK2, FANCL, PALB2, PPP2R2A, RAD51B, RAD51C, RAD51D, or other DNA repair genes) via CLIA certified testing....

≥50% PSA decline was 79%, 67%, and 85% of pts in Arms 1, 2, and 3, respectively. Median PSA nadir (ng/mL) (95% CI) Arms 1-3: 2.17 (0.44, 49.27), 3.10 (0.83, 12.01), and 0.50 (0.10, 2.13), respectively. In mCRPC pts with inactivating BRCA1, BRCA2 and/or ATM alterations Abi/pred + olaparib was well tolerated and resulted in longer PFS and better PSA response vs either agent alone.

Tumor samples from 37 patients with advanced or metastatic prostate cancer were analyzed….Two patients with ATM mutations received olaparib as fourth and fifth line of treatment respectively with stable disease as best response.

Patients were randomized 1:1 under a “pick-the-winner” design to 400mg or 300mg of olaparib BID...Subgroup analyses per altered gene identified indicated response rates for: BRCA1/2 of 80% (24/30; mPFS 8.1mo); PALB2 57% (4/7; mPFS 5.3mo); ATM 37% (7/19; mPFS 6.1mo); CDK12 25% (5/20; mPFS 2.9mo); others [ATRX, CHEK1, CHEK2, FANCA, FANCF, FANCG, FANCI, FANCM, RAD50, WRN] 20% (4/20; mPFS 2.8mo).

Of these 16 patients, 14 (88%) had a response to olaparib, including all 7 patients with BRCA2 loss (4 with biallelic somatic loss, and 3 with germline mutations) and 4 of 5 with ATM aberrations.

In patients with at least one alteration in BRCA1, BRCA2, or ATM (Cohort A), the primary endpoint of PFS was significantly longer for the olaparib group (7.4 months) than the control group (3.6 months) with HR = 0.34, 95% CI, 0.25–0.47; p < .001.