Clinical implementation of 177Lu-PSMA-617 (LuPSMA) at a major academic center: Initial experiences

108

Background: LuPSMA received FDA approval in March 2022 for patients with PSMA-positive metastatic castrate-resistant prostate cancer (mCRPC). Clinical implementation of this treatment requires multidisciplinary team (MDT) involvement and has been beset by challenges in drug supply. We established a joint DFCI GU/Nuclear Medicine Tumor Board (GU-NM TB) to review patients for therapy, and our initial experiences are described. Methods: A joint GU-NM TB was established. All patients with mCRPC who had received at least one prior chemotherapy and a novel hormonal agent were considered eligible and referred to TB through an online referral system after undergoing PSMA-PET/CT. Case details, including prior treatment history, performance status and organ function, and PET/CT imaging were reviewed at TB, with patients either being approved, deferred, or declined for LuPSMA therapy. Patients were scheduled for therapy on a first-come first-served basis. Treatment was delivered per standard-of-care at 180-200 millicurie doses every 6 weeks within NM. A questionnaire was sent to 25 referring physicians 2 months after implementation of the TB to evaluate the referral process. Results: Between May-September 2022, a total of 108 patients were referred for LuPSMA therapy. Median age at time of referral was 73 (range 52-93), and 90% of patients were Caucasian. Median duration between PSMA-PET/CT and TB review was 10 days (IQR 6-17). 84 patients (78%) were approved for therapy, 16 (15%) were deferred and 7 (6%) were declined (reasons including absence of prior chemotherapy, high risk for toxicities, poor performance status); 1 patient died before TB review. Prior therapies included docetaxel (84%), cabazitaxel (56%), abiraterone (67%), enzalutamide (57%), darolutamide (23%), radium-223 (21%) and apalutamide (7%). Median number of prior treatments was 4 (range 2-12). Sites of disease on PSMA-PET/CT included bone (81%), pelvic lymph nodes (42%), extrapelvic lymph nodes (88%), lung (27%) and liver (22%). As of September 2022, a total of 40 patients (48%) have received at least 1 cycle of therapy and 17 (20%) have received 2 cycles; 6 patients (7%) approved for therapy died before receiving 177Lu-PSMA-617. Of the patients that have received 1 cycle of therapy, median duration between TB acceptance and C1 was 52 days (range 32-114). Out of 13 survey respondents, all 13 (100%) reported that their overall experience of the referral process was positive or very positive, and 12 (92%) noted that the Tumor Board had provided additional clinical insights on occasion or frequently. Conclusions: Due to drug supply shortages, <50% of patients approved for LuPSMA therapy have started treatment to date. Median time between TB approval and start of therapy was 7-8 weeks, with 7% of patients dying before receiving therapy. Establishment of a GU-NM TB to review cases and facilitate treatment was viewed favorably by treating physicians.

Addition of Germline Testing to Tumor-Only Sequencing Improves Detection of Pathogenic Germline Variants in Men With Advanced Prostate Cancer

PURPOSE

Guidelines recommend somatic and germline testing for men with advanced prostate cancer (PCa). Barriers to widespread implementation result in underutilization of germline testing. Somatic testing alone risks missing pathogenic germline variants (PGVs). We sought to determine whether the addition of germline testing to tumor-only sequencing improves detection of PGVs in men with advanced PCa. Secondarily, we sought to define the added value of combining somatic and germline testing to optimize detection of clinically actionable alterations.

PATIENTS AND METHODS

We analyzed results of independent germline testing and tumor-only sequencing from 100 men with advanced PCa from a prospective clinical trial (ClinicalTrials.gov identifier: NCT03328091). The primary outcome was the proportion of PGVs not reported with tumor-only sequencing. The secondary outcome was the association of locus-specific loss of heterozygosity for PGVs in homologous recombination genes with clinical-genomic features.

RESULTS

In the 100 men who underwent germline testing and tumor-only sequencing, 24 PGVs were identified, 17 of which were clinically actionable, in 23 patients. Tumor-only sequencing failed to report four (17%) of the PGVs. One additional PGV (4.2%) had variant allele frequency on tumor-sequencing below the threshold for follow-up germline testing. When integrating tumor-only sequencing with germling testing results, 33% of patients harbored clinically actionable alterations. Rates of locus-specific loss of heterozygosity were higher for BRCA2 PGVs in castration-resistant PCa than PGVs in other homologous recombination genes in hormone-sensitive PCa (P = .029).

CONCLUSION

Tumor-only sequencing failed to report more than 20% of PGVs in men with advanced PCa. These findings strongly support guideline recommendations for universal germline and somatic testing in this population. Combining tumor and germline sequencing doubled the chance of detecting a clinically actionable alteration.

Sacituzumab govitecan (SG) plus enfortumab vedotin (EV) for metastatic urothelial carcinoma (UC) progressing on platinum-based chemotherapy and PD1/L1 inhibitors (ICB): Double antibody drug conjugate (DAD) phase I trial

TPS588

Background: There have been multiple advances in therapy of advanced urothelial carcinoma following platinum and ICB; SG and EV are both FDA approved in this space though durations of response are short and overall survival limited at < 13 months. Given different mechanisms of action, non-overlapping toxicities and potential for synergy, EV and SG is hypothesized to have manageable toxicities and demonstrate additive anti-tumor activity. Methods: NCT04724018 is a single-center (Dana-Farber/Harvard Cancer Center), open-label, non-randomized phase I trial using a Bayesian Optimal Interval design. SG and EV agents are administered intravenously (IV) on days 1 and 8 every 3 weeks (1 cycle) until progression or intolerable toxicities. Laboratory evaluation is performed on days 1 and 8 every cycle with additional blood collected throughout treatment for pharmacokinetic and antidrug antibody studies. Imaging is performed at baseline and every 6 weeks for the first 4 cycles followed by every 9 weeks thereafter. Up to 4 dose levels of the combination of SG and EV are studied with a starting dose of SG of 8 mg/kg and EV of 1 mg/kg (dose level 1) with additional dose escalations outlined in table. Dose de-escalation of SG to 6 mg/kg with the starting dose of EV 1 mg/kg (dose level -1) is permitted. A total of 3 to 18 patients are expected to be enrolled in current dose level depending on dose limiting toxicities (DLTs). DLT is assessed during cycle 1 of therapy and toxicities are captured up to 4 weeks after the last dose of therapy and being defined by ≥1 of the following: neutropenic fever, thrombocytopenic bleeding, grade 3 neuropathy, of any duration and any other grade ≥3 non-hematologic toxicity to include hyperglycemia (except alopecia) lasting >1 week or requiring >3 weeks interruption of therapy or dose reduction. The first patient per 3-patient cohort is required to complete 1 full cycle (3 weeks) before additional patients can be enrolled in that cohort. Therefore, up to 24 patients may be accrued. Trial continues to enroll at dose level one. Clinical trial information: NCT04724018. [Table: see text]

Initial results of a phase II study of nivolumab(N) and ipilimumab(I) in genitourinary malignancies with neuroendocrine differentiation

569

Background: Patients with metastatic genitourinary malignancies with neuroendocrine have limited therapeutic options following platinum therapy. Given encouraging results in initial cohort analysis for small cell urinary tract carcinoma, a cohort of any genitourinary malignancy with neuroendocrine differentiation was added to a multicenter, single arm, multi-cohort phase II trial to evaluate the efficacy of N and I in this setting. (NCT 03333616) Methods: Eligible patients had metastatic or locally advanced genitourinary malignancy with neuroendocrine differentiation with an ECOG performance status of 0-2; they may have received any line of prior therapy excluding prior immunotherapy. Patients underwent baseline biopsy and received treatment with N 3 mg/kg and I 1 mg/kg intravenously every 3 weeks for 4 cycles with continued maintenance of N 480 mg IV every 4 weeks. Imaging was performed at 12 weeks and then every 8 weeks through month 6 and then every 12 weeks thereafter. The primary endpoint was investigator assessed objective response rate (ORR) by RECIST 1.1. Results: A total of 27 patients were enrolled between 06/27/2018 and 06/21/2021, 10 (37%) had urinary tract cancer and 17 (63%) had prostate cancer (19 in expansion cohort, 3 urinary tract and 5 prostate cancer from earlier cohorts). The majority (n=25, 93%) patients received prior systemic therapy. Nine (33%) patients received all 4 doses of N and I during the induction period. Nine (33%) patients (7 of whom received 4 cycles N+I) received N maintenance (median number of cycles 9 (range, 2-37)). Median follow-up was 6.8 (range, 0.9-37.3) months. Objective response was achieved in 8 (30%, 80% CI 18%-44%) patients (Table). Median duration of response was not reached with 4 patients maintaining response >9 months. Median progression-free survival time was 2.6 (95% CI 1.8-6.5) months At time of analysis, 13 (48%) death events were reported due to progressive disease, in which 3 were bladder and 10 were prostate cancer. 8 (30%) patients developed treatment-related grade 3 or higher toxicities; one grade 5 toxicity was deemed treatment-unrelated. Conclusions: In this study we demonstrate N+I resulted in objective responses in patients with genitourinary malignancy with neuroendocrine differentiation. ORR of 50% in small cell carcinoma is bladder cancer is noteworthy and will be evaluated further in ongoing expansion cohort of bladder or upper tract carcinoma with variant histology. Clinical trial information: NCT03333616. [Table: see text]

Primary care physician (PCP) referral patterns for prostate cancer (PC) patients: Web-based survey

228

Background: Prostate cancer (PC) is the most common cancer and second most common cause of cancer related death in men. The therapeutic options for PC patients are rapidly expanding making treatment decisions more complex. For patients with high-risk PC, significant body of evidence demonstrates that multidisciplinary approach improves outcome. PCP has a major role in early detection, provision of counseling, appropriate referral and management of metabolic side effects (SE) of androgen deprivation therapy (ADT). We conducted a survey among PCP’s to understand their referral patterns. Methods: We emailed a 10 question web based survey to around 300 practicing PCP’s in the Boston area. Of them, 56 responded. We analyzed the responses using independent t test for demographics and ANOVA for years of experience of the individual physician. Additional multivariate analysis was done using all independent variables together. Results: 30.3% of the physicians never feel the need to refer a newly diagnosed prostate cancer patient to a medical oncologist (MO). 60.8% of the PCP’s anticipate that urologist should refer the patients to a MO. Only 9% of PCP’s feel responsible for managing the SE of ADT. 46.4% anticipate urologist and 44.6 % anticipate oncologist to manage the SE of ADT. Female physicians appear to be more comfortable in providing counseling to the newly diagnosed PC patients than the male physicians (P=0.001). Male physicians and US medical graduates tend to refer to the MO most often than the female physicians and foreign medical graduates (P=0.013 and p=0.015 respectively). On multivariate analysis US medical graduates with higher years of experience are more comfortable providing the counseling and discussion of newer treatment options for a newly diagnosed PC (p=0.011 and 0.016 respectively). Overall 44.6% are not aware of newer treatment options for castration resistant PC. Conclusions: In the era of expanding armamentarium of treatments for PC, our results indicate the need to increase the awareness of PCP’s regarding the available treatments and emphasize the importance of multidisciplinary approach to better serve the PC patients with appropriate and timely referrals.

Role of sentinel lymph node biopsy (SLNB) and preoperative MRI in the management of patients with pure high-grade ductal carcinoma in situ (DCIS)

87

Background: The overall incidence of SLN metastases in pure DCIS is < 1% and the results of SLNB do not usually impact treatment or survival but adds significant surgical morbidity. In addition, there is no evidence regarding the role of preoperative MRI in the management of DCIS. The purpose of our study was to identify the efficacy of SLNB and the benefit of preoperative MRI in high-grade DCIS. Methods: We performed retrospective review of 364 patients with DCIS, identified through our cancer registry database, that were seen from 2003 to 2012 at our institution. Of these, 62 patients were diagnosed with high-grade DCIS (Grade 3 or 2 with comedonecrosis) by core needle biopsy, and underwent SLNB. The remaining 302 patients had either low-grade DCIS or did not have a SLNB. Results: Median age was 56 years (range 33-80). Sixty two patients had high-grade DCIS on definitive excision and 2/62 patients were noted to have small invasive focus of disease. 15/62 (24.19%) patients underwent mastectomy and 47/62(78.1%) underwent lumpectomy. No patient had a positive SLN (0/62). 15/62 (24.2%) patients had breast MRI preoperatively and among them, in 5 (33.3%) patients, MRI findings changed the surgical decision to mastectomy. Among these 5 mastectomy patients, four of them (80%) had pathologically confirmed findings consistent with preoperative MRI suspicions. In lumpectomy patients, close margin of less than 1mm was seen in 4/9 (44.4%) patients with staging MRI and in 24/38 (63.15%) patients without MRI (p = 0.45. Fisher’s exact test). However the positive margin leading to re-excision was seen in 2/9 (22.2%) patients who underwent lumpectomy with staging MRI, and 9/38 (23.6%) patients who underwent lumpectomy without staging MRI. Conclusions: In our study, no patient with high grade DCIS had a positive sentinel node suggesting that routine sentinel node biopsy is not necessary in DCIS patients. The use of MRI changed the surgical planning in 33.3% of patients, but did not improve the surgeon's ability to achieve clear margins.

Clinical outcome of preoperative breast MRI for early-stage breast cancer

42

Background: Preoperative breast magnetic resonance imaging MRI is used in clinical practice to improve oncologic outcome of breast cancer. Concerns over increased rate of unnecessary mastectomies and additional biopsies have been raised. The purpose of our study is to review the outcome of preoperative breast MRI at our institution. Methods: The current study is a retrospective review of 215 patients with early stage breast cancer who underwent definitive surgery. Breast MRI is being used at our institution within the context of multidisciplinary approach. Patients who had complete clinical, radiologic, and pathological data available were identified and formed the basis of this analysis. Results: 215 patients were diagnosed with breast cancer stage I-II in the period of 2006-2012 and had complete data for review. 92 patients out of 215 (43%) had breast MRI prior to definitive surgery. both groups were different in regard of age. Rate of breast conservative surgery, mastectomies, and re-excision for positive margins was similar in both groups. 6 patients out of 12 patients who had breast MRI and underwent bilateral mastectomies were found to have abnormal pathological findings (DCIS 3, LCIS 1, invasive ductal carcinoma 1, and focal epithelial atypia 1). Time from first diagnostic procedure to definitive surgery was similar in both groups (29 days vs. 27.5 days). 38 (41%) patients out of 92 who had breast MRI underwent additional breast biopsies for suspicious lesions with only 8 (21%) patients found to have abnormal pathological findings. Conclusions: Use of breast MRI prior to definitive surgery for early stage breast cancer was associated with increased rate of additional biopsies for suspicious lesions with no favorable effect on re-excision rate. [Table: see text]

Delayed local recurrence following radiation therapy for muscle-invasive bladder cancer emphasizing the need for lifelong surveillance: a case report

We report a case of 68 years old gentleman who developed a delayed local recurrence, 30 years following curative radiation treatment for muscle invasive bladder cancer. This case emphasizes the importance of lifelong post treatment surveillance for bladder cancer.