Changes in immunohistochemical staining of PSA, PAP, and TURP-27 following irradiation therapy for clinically localized prostate cancer

Current approaches, challenges and future directions for monitoring treatment response in prostate cancer

Prostate cancer is the most commonly diagnosed non-cutaneous neoplasm in men in the United States and the second leading cause of cancer mortality. One in 7 men will be diagnosed with prostate cancer during their lifetime. As a result, monitoring treatment response is of vital importance. The cornerstone of current approaches in monitoring treatment response remains the prostate-specific antigen (PSA). However, with the limitations of PSA come challenges in our ability to monitor treatment success. Defining PSA response is different depending on the individual treatment rendered potentially making it difficult for those not trained in urologic oncology to understand. Furthermore, standard treatment response criteria do not apply to prostate cancer further complicating the issue of treatment response. Historically, prostate cancer has been difficult to image and no single modality has been consistently relied upon to measure treatment response. However, with newer imaging modalities and advances in our understanding and utilization of specific biomarkers, the future for monitoring treatment response in prostate cancer looks bright.

Expression and immunotherapeutic targeting of the SSX family of cancer-testis antigens in prostate cancer

Recent U.S. Food and Drug Administration approval of the first immunotherapy for prostate cancer encourages efforts to improve immune targeting of this disease. The synovial sarcoma X chromosome breakpoint (SSX) proteins comprise a set of cancer-testis antigens that are upregulated in MHC class I-deficient germline cells and in various types of advanced cancers with a poor prognosis. Humoral and cell-mediated immune responses to the SSX family member SSX2 can arise spontaneously in prostate cancer patients. Thus, SSX2 and other proteins of the SSX family may offer useful targets for tumor immunotherapy. In this study, we evaluated the expression of SSX family members in prostate cancer cell lines and tumor biopsies to identify which members might be most appropriate for immune targeting. We found that SSX2 was expressed most frequently in prostate cell lines, but that SSX1 and SSX5 were also expressed after treatment with the DNA demethylating agent 5-aza-2'-deoxycytidine. Immunohistochemical analysis of microarrayed tissue biopsies confirmed a differential level of SSX protein expression in human prostate cancers. Notably, SSX expression in patient tumor samples was restricted to metastatic lesions (5/22; 23%) and no expression was detected in primary prostate tumors examined (0/73; P < 0.001). We determined that cross-reactive immune responses to a dominant HLA-A2-specific SSX epitope (p103-111) could be elicited by immunization of A2/DR1 transgenic mice with SSX vaccines. Our findings suggest that multiple SSX family members are expressed in metastatic prostate cancers which are amenable to simultaneous targeting.

Secondary prostatic adenocarcinoma: A cytopathological study of 50 cases

Positive diagnosis of metastatic prostate adenocarcinoma (PAC) can be made by microscopic examination of the cytologic specimens and immunostaining for prostate-specific antigen (PSA) and prostate acid phosphatase (PAP). Immunohistochemical markers have been known to display negative, weak, or focal staining in poorly differentiated PAC and in patients with prior hormonal and/or radiation therapy. The purpose of this study is to characterize the cytopathology of metastatic PAC as it has not been documented in large series. Fifty cases of metastatic PAC with cytological specimens consisting of 41 fine-needle aspiration biopsies (FNAB), 6 pleural fluid aspirates, and 3 catheterized urine samples were reviewed and correlated with the surgical specimens and the clinical charts. Immunostaining for PSA, PAP, cytokeratin AE1/3, cytokeratin 7 (CK7), cytokeratin 20 (CK20), vimentin, and carcinoembryonic antigen (CEA) was done. Mean patient age was 77 +/- 8 yr; serum PSA, 4.1 +/- 2.3; and primary PAC Gleason score, 8.1 +/- 1.5. Cytologically, the specimens consisted of cell clusters or cell sheets with overlapping uniform hyperchromatic nuclei with or without nucleoli. Twelve cases were not reactive to PSA and PAP and 44 cases displayed negative immunoreactivity to both CK7 and CK20. Carcinoid-like lesions and small cell carcinomas were seen in 4 cases and were misdiagnosed as nonprostatic origin based on the following features: negative immunoreactivity to PSA and PAP with or without positive reactivity to CEA, and different histopathological features when compared with the primary PAC. In addition to the frequency of high-grade PAC, awareness of the negative immunoreactivity to PSA and PAP, the discrepancy in the histopathological patterns between the primary and secondary tumors, especially the frequent neuroendocrine differentiation, are helpful features for the diagnosis of metastases of prostatic origin.

Comparison of anti-prostate-specific membrane antigen antibodies and other immunomarkers in metastatic prostate carcinoma

OBJECTIVES

To compare the immunohistochemical properties of the 7E11 anti-prostate-specific membrane antigen (anti-PSMA) monoclonal antibody (mAb) with the recently developed anti-PSMA mAb, PM2J004.5, and with other common immunomarkers in metastatic prostate cancer. PSMA is a type II integral membrane glycoprotein highly expressed in prostate cancer cells. The mAb 7E11 is currently used in the radioisotopic evaluation of prostate cancer, and its immunohistochemical properties have been examined in primary prostate cancer specimens.

METHODS

We examined 23 formalin-fixed, paraffin-embedded, metastatic prostate carcinoma specimens from various anatomic sites, including bone, lymph node, liver, lung, and soft tissue. Using the biotin-streptavidin method, we performed immunohistochemical reactions with the anti-PSMA mAbs 7E11 and PM2J004.5 and with antibodies to prostate-specific antigen and prostatic acid phosphatase. The immunoreactions were scored by pathologists unaware of the clinical and pathologic data according to a staining intensity scale and the percentage of cells stained.

RESULTS

All four mAbs consistently stained the metastatic prostate cancer specimens. In 2 (8.7%) of 23 cases, however, the prostate-specific antigen immunoreaction was negative but the anti-PSMA mAbs had positive staining. Although 7E11 and PM2J004.5 had a similar staining intensity and percentage of cells stained for most specimens, in 3 (13%) of 23 specimens, 7E11 had less intense staining. None of the specimens were negative for all four antibodies.

CONCLUSIONS

Anti-PSMA mAbs consistently immunoreacted with metastatic prostate cancer specimens and were positive in instances when prostate-specific antigen staining was negative. The anti-PSMA mAbs demonstrated similar staining patterns; however, in select cases, the PM2J004.5 mAb did show more intense staining. The anti-PSMA mAbs 7E11 and PM2J004.5 are useful in the pathologic evaluation of paraffin-embedded metastatic prostate cancer specimens.

Free-to-total prostate-specific antigen ratios 18-24 months following external beam radiation for adenocarcinoma of the prostate

BACKGROUND AND OBJECTIVES

The purpose of this study was to evaluate free-to-total prostate-specific antigen (PSA) ratios after definitive external beam radiation therapy for men with adenocarcinoma of the prostate (CaP).

METHODS

A prospective evaluation of percent free PSA in men following definitive external beam radiation therapy for CaP was compared to men with untreated CaP and men at very low risk for CaP. Statistical comparison of clinical and pathologic parameters was performed.

RESULTS

There was no statistically significant difference in free-to-total PSA ratios for men with newly diagnosed CaP and men with detectable PSA who were treated with external beam radiation therapy.

CONCLUSIONS

Free-to-total PSA ratios after definitive external beam radiation therapy for CaP are consistent with percent free PSA in patients with newly diagnosed CaP. This supports the theory that PSA from in situ prostate tissue following external beam radiation therapy is produced by malignant cells.

PSA for outcome prediction and posttreatment evaluation following radiation for prostate cancer: do we know how to use it?

Pretreatment prostate-specific antigen (PSA) has been shown to be a powerful predictor of expected outcome after radiation for prostate cancer. Additional measures such as recursive partitioning analysis and PSA Cancer Volume calculations are further refining this useful tool to provide the greatest degree of prognostic information. The post-treatment PSA level is also being used as a means to assess therapeutic efficacy rapidly and objectively. Although no single PSA value has been shown to equate to long-term clinical tumor control consistently, consensus has been reached regarding the value of a rising PSA level as an early surrogate for tumor recurrence. Since the first introduction of PSA as a tumor marker, we have become much more comfortable with what it means, the ways it can help us, and how to use it.

Prostate-specific antigen after radiation therapy. Prognosis by pretreatment level and post-treatment nadir

After external beam radiation therapy, pretreatment prostate-specific antigen (PSA) is the most powerful predictor of outcome as measured PSA (biochemical) failure. The post-treatment nadir levels of PSA that predict best for subsequent freedom from PSA failure are debatable, and many nadir levels have been proposed as targets. Although lower nadirs generally are associated with superior outcomes, the identification of a single absolute nadir level was not selected at a recent ASTRO consensus conference. Rather, three consecutive PSA rises above the nadir, with date of failure at the midpoint between the nadir and first rise, were selected as a more useful end point for treatment failure.

Assessment of endpoints for clinical trials for localized prostate cancer

OBJECTIVES

The AUA Practice Guidelines Panel convened to address the issue of appropriate endpoints for assessment of treatment modalities for localized carcinoma of the prostate.

METHODS

A review of the literature and the design of existing clinical trials produced a consensus, which was presented to and critiqued by the members of the general conference.

RESULTS

The pitfalls associated with identification of local failure endpoints were discussed, and the more accurate endpoints of freedom from metastatic progression and overall survival were recognized. The strict definition that must be fulfilled for intermediate endpoints to become surrogates for metastasis free and/or survival endpoints was stressed. For more efficient and rapid conduct of future clinical trials, the urgent need to validate such surrogate endpoints by evaluation in randomized control trials is obvious. PSA, while an indicator of disease activity and a critical marker for estimating disease progression or regression in response to therapy, is not a surrogate for metastasis free or overall survival.

CONCLUSION

Until surrogate endpoints are validated, the committee has evaluated the endpoints in current use, reviewed their limitations, and stressed the importance of quality-of-life assessment together with the traditional endpoint assessment.

Absence of serum prostate-specific antigen and loss of tissue immunoreactive prostatic markers in advanced prostatic adenocarcinoma after hormonal therapy: a report of two cases

We report two cases of advanced prostatic adenocarcinoma (PA) showing complete loss of three tissue immunoreactive prostatic markers, ie, prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), and Leu-7 (CD57), with absence of elevated serum PSA level, despite tumor progression after hormonal therapy with or without radiotherapy. The pretreatment serum PAP in the first case and serum PAP and PSA in the second case were elevated. In both cases, the prostatic adenocarcinoma in the initial transurethral resection specimens showed positive immunoreactivity with three prostatic markers. After treatment, in both cases, the serum PSA were undetectable, and tumor cell immunostaining for three prostatic markers was negative. In addition, the posttreatment tumors in both cases showed increased number of tumor cells with neuroendocrine differentiation in comparison those in the pretreatment tumors. Although early PA without elevated serum level of PSA is common, advanced PA with absence of elevated serum PSA, associated with presence of tissue immunoreactive prostatic markers are rare. This is the first report of advanced prostatic adenocarcinomas showing loss of tumor cell prostate-specific markers with absence of elevated serum PSA level after hormonal therapy despite tumor progression.