Androgen receptor, PARP signaling, and tumor microenvironment: the 'perfect triad' in prostate cancer?

Aberrations in the homologous recombination repair (HRR) pathway in prostate cancer (PCa) provide a unique opportunity to develop therapeutic strategies that take advantage of the reduced tumor ability to repair DNA damage. Poly-ADP-ribose polymerase (PARP) inhibitors (PARPi) have been shown to prolong the survival of PCa patients with HRR defects, particularly in those with Breast Cancer type 1 susceptibility protein/Breast Cancer type 2 susceptibility protein alterations. To expand the benefit of PARPi to patients without detectable HRR alterations, multiple preclinical and clinical studies are addressing potential synergies between PARPi and androgen receptor signaling inhibitors, and these strategies are also being evaluated in combination with other drugs such as immune checkpoint inhibitors. However, the effectiveness of these combining therapies could be hindered by multiple mechanisms of resistance, including also the role played by the immunosuppressive tumor microenvironment. In this review, we summarize the use of PARPi in PCa and the potential synergies with different molecular pathways. However, numerous unanswered questions remain, including the identification of the patient population that could benefit most from PARPi, determining whether to use PARPi as monotherapy or in combination, and finding the optimal timing of PARPi, expanding the use of genomic tests, and optimizing combination therapies.

Initial management approach for localized/locally advanced disease is critical to guide metastatic castration-resistant prostate cancer care.

BACKGROUND: Currently, several therapies are available for metastatic castration-resistant prostate cancer (mCRPC) but no specific clinical factors to personalize treatment. We first sought the prognostic value of duration on androgen-deprivation therapy (ADT) for hormone-sensitive prostate cancer (HSPC) in patients receiving androgen-receptor-signaling inhibitors (ARSI) for mCRPC. METHODS: A multicenter cohort of mCRPC patients who started ARSI between July 2011 and October 2021 was identified. Based on their initial disease burden and duration on ADT for HSPC, primary progressive (PP) men were classified into four groups: low/intermediate-risk localized disease (LOC) and high-risk localized/locally advanced disease (LAD) and short-term (ST) < 24 vs. long-term (LT) ADT ≥ 24 months, whereas de novo (DN) mHSPC were subdivided into short-time vs. long-time to CRPC. RESULTS: We included 919 mCRPC patients with a median age of 77 years [interquartile range (IQR) = 71-82)]. Median ADT duration in HSPC was 24 months (IQR = 14-40). Median follow-up was 91 months (IQR = 62-138), median OS and PFS from ARSI start were 20 (IQR 10-32) and 10 months (IQR = 5-19), respectively. In PP developing metastatic disease (n = 655, 71.3%), LOC and LAD with ST ADT had a greater than almost double-risk of death compared to LT ADT (LOC/ST: hazard ratio [HR] = 2.01; 95% CI 1.54-2.64; LAD/ST: HR = 1.73; 95% CI 1.34-2.24; p < 0.001). In the multivariate analysis including age, prognostic cohort, Gleason, ECOG, radical radiotherapy and prostatectomy, groups with ST ADT were associated with worse OS compared to LT ADT (LOC/ST: HR = 1.84; 95% CI 1.38-2.45; p < 0.001; LAD/ST: HR = 1.59; 95% CI 1.21-2.10; p < 0.001), along with ECOG > 2 (HR = 1.55; 95% CI 1.06-2.26; p = 0.03). There were also similar results of PFS. Moreover, long-time to CRPC in patients with history of DN mHSPC (n = 264, 28.7%) resulted in a better OS/PFS (HR = 0.76, 95% CI 0.56-1.02, p = 0.064 and HR = 0.74, 95% CI 0.55-0.99, p = 0.042, respectively). CONCLUSIONS: Our study showed that duration on ADT for mHSPC was significantly associated with survival in mCRPC undergoing ARSI. These findings suggest a possible connection between initial management of prostate tumour and a better prognostication in mCRPC. Prospective trials are warranted.

(11)C-Choline PET/CT in castration-resistant prostate cancer patients treated with docetaxel.

PURPOSE: To investigate the role of (11)C-choline PET/CT for evaluating the response to treatment in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with docetaxel in comparison with PSA response. METHODS: Inclusion criteria were (a) proven mCRPC, (b) docetaxel as first line of chemotherapy (docetaxel 75 mg/m(2) + prednisone 5 mg), and (c) (11)C-choline PET/CT and PSA values assessed before and after docetaxel administration. A total of 61 patients were retrospectively enrolled (mean age 68.9 years, range 57 - 84 years). (11)C-Choline PET/CT was performed at baseline before docetaxel treatment (PET1) and after the end of treatment (PET2). PSA values were measured before treatment (PSA1) and after treatment (PSA2). PET2 was reported as complete response (CR), partial response (PR) or stable disease (SD). Progressive disease (PD) was considered if a new lesion was seen. PSA trend was calculated from the change in absolute values between PSA1 and PSA2. A decrease of ≥50 % between PSA1 and PSA2 was considered a PSA response. Clinical, radiological and laboratory follow-up ranged from 6 to 53 months (mean 13.5 months). RESULTS: Of the 61 patients, 40 (65.5 %) showed PD on PET2, 13 (21.3 %) showed SD, 2 (3.4 %) showed PR, and 6 (9.8 %) showed CR. An increasing PSA trend was seen in 29 patients (47.5 %) and a decreasing PSA trend in 32 patients (52.5 %). A PSA response of ≥50 % was seen in 25 patients (41 %). Radiological PD was seen in 23 of the 29 patients (79.3 %) with an increasing PSA trend, in 16 of the 32 patients (50 %) with a decreasing PSA trend, and in 11 of the 25 patients (44 %) with a PSA response of ≥50 %. In the multivariate statistical analysis, the presence of more than ten bone lesions detected on PET1 was significantly associated with an increased probability of PD on PET2. No association was observed between PSA level and PD on PET2. CONCLUSION: Our results suggest that an increasing PSA trend measured after docetaxel treatment could be considered predictive of PD. In patients with decreasing PSA values (decreasing PSA trend and a PSA response of ≥50 %), (11)C-choline PET/CT may be useful to identify those with radiological progression despite a PSA response. Finally, the tumour burden, expressed as number of bone lesions on PET1, is significantly associated with an increased probability of PD on PET2.

Palliative embolization for metastases of the spine.

BACKGROUND: To present palliative selective and superselective arterial embolization with N-butyl-cyanoacrylate for cancer patients with spinal metastases. MATERIALS AND METHODS: We studied the files of 164 cancer patients (94 men and 70 women; mean age 57.6 years; range 35-81 years) treated from March 2003 to March 2013 with 178 selective arterial embolization procedures for metastases of the spine from variable primary cancers. We evaluated the technical success of the embolization procedure with post-procedural angiography, the clinical effect in pain relief, need for analgesics and tumor size reduction, and the embolization-related complications. RESULTS: Post-embolization angiography showed complete occlusion of the pathological feeding vessels in all procedures. Pain score and need for analgesics reduced by 50 % in 159 patients (97 %); no response was achieved in five patients with metastases of the sacrum. The mean duration of pain relief was 9.2 months (range 1-12 months). Metastatic tumor size reduced from a mean of 5.5 cm (range 3.5-7.5 cm) pre-embolization to a mean of 4.5 cm (range 3-5 cm) at the 6-month follow-up; the difference was not statistically significant. Ninety-three patients (56.7 %) experienced embolization-related complications the most common being post-embolization syndrome (80 patients, 48.8 %) followed by leg paresthesias (ten patients, 6 %), and rupture of a lumbar artery (one patient, 0.6 %). CONCLUSION: Selective arterial embolization with N-butyl-cyanoacrylate should be considered for pain palliation of patients with metastases of the spine. However, pain relief is temporary, and complications, although minor may occur.

Treatment strategy for rectal cancer with synchronous metastasis: 65 consecutive Italian cases from the Bologna Multidisciplinary Rectal Cancer Group.

BACKGROUND: Twenty percent of rectal cancer patients have synchronous distant metastasis at diagnosis. At present, the treatment strategy in this patient setting is not well defined. This study in one institution evaluates the treatment strategy of three different patient groups. PATIENTS AND METHODS: Between January 2000 and July 2011, 65 patients with M1 rectal cancer were evaluated. Three different groups were defined: rectal cancer with resectable metastatic disease (group A); rectal cancer with potentially resectable metastatic disease (group B), and rectal cancer with unresectable metastatic disease (group C). RESULTS: Group A included 11 patients (16.9%), group B 28 patients (43.1%) and group C 26 patients (40%). Forty-three (66.2%) patients underwent surgery for primary rectal cancer, and 30 (46.2%) patients for metastasis resection (23 liver, 4 lung and 3 ovary). Median overall survival (OS) by group was: 51 (5-86; group A), 32 (24-40; group B) and 16 (7-26; group C) months. Patients undergoing metastasis resection have higher median OS than unresected patients (44 vs. 15 months; p < 0.001). CONCLUSIONS: The treatment strategy in synchronous metastatic rectal cancer must consider the possibility of distant metastasis resection. Long-term survival can be achieved using an integrated approach.

Clinically-staged T3N0 rectal cancer: is preoperative chemoradiotherapy the optimal treatment?

BACKGROUND: Preoperative chemoradiotherapy has been widely adopted as the standard of care for stage II-III rectal cancers. However, patients with T3N0 lesions had been shown to have a better prognosis than other categories of locally advanced tumor. Thus, neoadjuvant chemoradiation is likely to be overtreatment in this subgroup of patients. Nevertheless, the low accuracy rate of preoperative staging techniques for detection of node-negative tumors does not allow to check this hypothesis. We analyzed a group of patients with cT3N0 low rectal cancer who underwent neoadjuvant chemoradiotherapy with the purpose of evaluating the incidence of metastatic nodes in the resected specimens. METHODS: Between January 2002 and February 2008, 100 patients with low rectal cancer underwent clinical staging by means of endorectal ultrasound, computed tomography, positron emission tomography, and magnetic resonance imaging. All patients received preoperative 5-fluorouracil-based chemoradiotherapy and surgical resection with curative aim. RESULTS: Of 100 patients with locally advanced rectal cancer, 32 were clinically staged as T3N0M0. Pathological analysis showed the presence of lymph node metastases in nine patients (28%) (node-positive group). In the remaining 23 cases, clinical N stage was confirmed at pathology (node-negative group). Node-positive and node-negative groups differ only in the number of ypT3 tumors (P < .01). CONCLUSIONS: Our results indicate that immediate surgery for patients with cT3N0 rectal cancer represents an undertreatment risk in at least 28% of cases, making necessary the use of postoperative chemoradiotherapy. Preoperative chemoradiotherapy should be the therapy of choice on the grounds of the principle that overtreatment is less hazardous than undertreatment for cT3N0 rectal cancers.