The results of treatment with high-dose chemotherapy and peripheral blood stem cell support for gestational trophoblastic neoplasia.

OBJECTIVE: The objective of the study was to evaluate the effect of high-dose chemotherapy (HDC) with peripheral blood stem cell support (PBSCS) on survival of patients with gestational trophoblastic neoplasia (GTN) with either refractory choriocarcinomas or a poor-prognosis placental site/epithelioid trophoblastic tumours (PSTT/ETTs). METHODS: Databases of two referral centres for gestational trophoblastic disease were searched, and 32 patients treated with HDC between 1994 and 2015 were identified. Tissue samples were retrieved for genetic evaluation. Cox regression analyses were performed to identify possible predictors of overall survival (OS). RESULTS: HDC induced a sustained complete response in 7 patients. Overall, 41% (13/32) of the patients remained disease free after HDC with or without additional treatment. Patients who survived had much lower human chorionic gonadotropin (hCG) values (all ≤12 IU/L) before and after HDC than those who died of disease. Univariable Cox regression analysis demonstrated that hCG >12 IU/L before or after HDC, International Federation of Gynaecology and Obstetrics (FIGO) stage II-IV and presence of metastases at the time of diagnosis were significantly associated with adverse OS. However, only hCG values before HDC remained significant in a multivariable model (p < 0.001). Five of 11 (45%) patients with PSTT/ETT presenting ≥48 months after antecedent pregnancy and 6 of 14 (43%) patients with refractory choriocarcinoma were in remission. Three treatment-related deaths occurred. CONCLUSIONS: Despite 3 treatment-induced deaths, HDC with PBSCS appears to be active in salvaging selected patients with poor-prognosis PSTT/ETTs and refractory choriocarcinomas. Low hCG values before HDC seems a beneficial predictor of OS and may suggest that HDC acts more like a consolidation therapy.

Late spontaneous resolution of persistent molar pregnancy.

OBJECTIVE: To determine the outcome of women with persistently raised but falling human chorionic gonadotrophin (hCG) levels 6 months after surgical evacuation of a molar pregnancy. DESIGN: An 11-year retrospective review. SETTING: The United Kingdom supra-regional trophoblastic disease treatment centres at Weston Park Hospital (Sheffield) and Charing Cross Hospital (London). POPULATION: Women with raised but falling serum human chorionic gonadotrophin (hCG) levels 6 months after evacuation of a molar pregnancy. METHODS: Retrospective case note review of eligible women identified by the electronic databases held at each supra-regional centre. MAIN OUTCOME MEASURES: The proportion of women that attain normal hCG levels spontaneously without chemotherapy. In addition, rates of gestational trophoblastic neoplasia (GTN), drug resistance, disease relapse and overall survival are reported. RESULTS: Thirty-five women with molar pregnancy and raised but falling serum hCG levels continued surveillance 6 months after evacuation. Levels of hCG in 30 of the patients (86%) fell to normal levels spontaneously. One woman defaulted follow up prior to hCG normalisation (3%) and the remaining four women (11%) were treated with chemotherapy due to a plateau or rise in serum hCG levels indicating GTN. All treated women were successfully salvaged by either first (n = 1) or second line (n = 2) chemotherapy or found to have persistently raised low level hCG of uncertain clinical relevance (n = 1). No women developed relapsed disease and overall survival was 100%. CONCLUSIONS: Women with a molar pregnancy and a raised but falling hCG level beyond 6 months from uterine evacuation can be safely observed with regular hCG monitoring and can usually avoid potentially toxic chemotherapy. TWEETABLE ABSTRACT: Women with treated molar pregnancy may avoid chemotherapy if 6-month hCG levels are raised but falling.

Risk of recurrent molar pregnancies following complete and partial hydatidiform moles.

STUDY QUESTION: What is the risk of further molar pregnancies for women with one or more hydatidiform moles (HM) in relation to molar subtype. SUMMARY ANSWER: Women with a complete hydatidiform mole (CM) have a 1 in 100 and 1 in 4 risk of further CM after one or two consecutive CM, respectively, while women with a partial hydatidiform mole (PM) have only a small increase in risk for further molar pregnancies. WHAT IS KNOWN ALREADY: Women with a molar pregnancy have an increased risk of further HM. A small subgroup of women with recurrent HM has an autosomal recessive condition, familial recurrent hydatidiform moles (FRHM), that predisposes them to molar pregnancies. STUDY DESIGN, SIZE, DURATION: A retrospective study of subsequent pregnancies in 16 000 women registered at a centralized referral centre, with a CM or PM, between 1990 and 2009. PARTICIPANTS/MATERIALS, SETTING, METHODS: One hundred and sixty-six women with two or more molar pregnancies were identified from electronic records and patient notes. Histopathological features of all molar tissue were reviewed in these cases and genotyping performed where diagnosis was not possible on the basis of histopathological features alone. In addition, genotyping of molar tissue was performed in all cases of women with three or more CM to establish whether the tissue was diploid and biparental or androgenetic. MAIN RESULTS AND THE ROLE OF CHANCE: This study confirms an increased recurrence risk of ∼1% for a second molar pregnancy and in addition that this risk is associated with CM rather than PM. The data further indicate that the risk of a third HM is associated almost exclusively with CM and enabled an estimate that 1 in 640 women registered with a CM has the rare condition FRHM. The study also found that there was no significant difference between the risk of developing gestational trophoblastic neoplasia (GTN) for typical sporadic CM and the diploid biparental CM associated with FRHM (GTN; proportion difference 0.05, Z = 0.87, P = 0.29). LIMITATIONS, REASONS FOR CAUTION: While pathology was reviewed for all women with two or more molar pregnancies, not all cases registered underwent central review particularly those women registered in the early 1990s. It is therefore possible that the total number of CM and PM may differ slightly from that stated. While women were followed for a minimum of 5 years, it is possible that some women may subsequently have further molar pregnancies that will not have been included in the present study. WIDER IMPLICATIONS OF THE FINDINGS: This is the largest study to date on recurrence for molar pregnancies, and as such provides the most detailed information so far regarding the risk of further molar pregnancies for women with a PM or CM. Furthermore, the data provide new insights into the incidence of the rare autosomal recessive condition, FRHM, important information for counselling women with molar pregnancies. STUDY FUNDING/COMPETING INTERESTS: No competing interests declared. No funding was obtained for this study.

A retrospective study to evaluate single agent methotrexate treatment in low risk gestational choriocarcinoma in the United Kingdom.

OBJECTIVE: To determine whether single agent chemotherapy with intramuscular methotrexate 50mg administered on days 1, 3, 5, and 7 and oral folinic acid 15mg administered on days 2, 4, 6, and 8 in 2 weekly cycles (IM MTX/FA) is an effective treatment regimen for patients with low risk gestational choriocarcinoma. METHOD: Electronic databases were searched to identify patients with gestational choriocarcinoma at the Sheffield and Charing Cross supra-regional trophoblastic disease centres from January 2000 to December 2011. Clinical notes of low risk patients with FIGO score 0-6 were retrospectively reviewed to assess treatment outcomes and subsequent relapse. RESULTS: 65 patients were identified with low risk choriocarcinoma. Serum hCG levels normalised in 24 patients without the requirement of chemotherapy (19 with histological confirmation, 4 highly suspicious histology and 1 clinical diagnosis). Of 23 patients with histologically confirmed choriocarcinoma, 8 (35%) had a sustained complete response to IM MTX/FA and did not relapse. Both patients with FIGO score 6, and 1 patient with FIGO stage III metastatic disease developed resistance to IM MTX/FA and required further treatment. Despite the development of drug resistance or relapse all patients were successfully salvaged by subsequent treatments. CONCLUSIONS: Not all patients with low risk choriocarcinoma that have had primary intervention prior to staging, such as surgical resection or uterine evacuation will require chemotherapy, providing hCG levels continue to decline to normal. Low risk (FIGO 0-5) patients should initially receive IM MTX/FA due to its low toxicity, outpatient administration and reasonable efficacy. Patients with FIGO score 6 or FIGO stage III disease should make an informed choice between IM MTX/FA and combination chemotherapy.

The relationship of maternal age to molar pregnancy incidence, risks for chemotherapy and subsequent pregnancy outcome.

The national registration and treatment service for molar pregnancies in the UK allows for the collection of accurate data on this relatively rare diagnosis. In England and Wales, between 2000 and 2009, 5,793 patients with complete moles and 7,790 with partial moles were registered, compared with a total of 8,242,511 conceptions. The overall molar pregnancy incidence was 1 for every 607 conceptions (complete mole 1:1,423; partial mole 1:1,058), but with major variations with age. For complete moles, the risk varied from < 1:1,000 for ages 18-40, to 1:156 for women aged 45 and 1:8 for those aged 50 and above. The overall risk of requiring chemotherapy after a complete mole was 13.6% and 1.1% for partial mole, while the risk of a further molar pregnancy in the next conception was 1:68 but each of these figures have considerable variations with age. These modern statistics on molar pregnancy risks and outcomes should be of value to clinicians and their patients, while discussing this rare diagnosis.

Early prediction of treatment resistance in low-risk gestational trophoblastic neoplasia using population kinetic modelling of hCG measurements.

BACKGROUND: In low-risk gestational trophoblastic neoplasia (GTN) patients, a predictive marker for early identification of methotrexate (MTX) resistance would be useful. We previously demonstrated that kinetic modelling of human chorionic gonadotrophin (hCG) measurements could provide such a marker. Here we validate this approach in a large independent patient cohort. METHODS: Serum hCG measurements of 800 low-risk GTN patients treated with MTX were analysed. The cohort was divided into Model and Test data sets. hCG kinetics were described from initial treatment day to day 50 using: '(hCG(time))=hCG0*exp(-k*time)+hCGres', where hCGres is the modelled residual production, hCG0 is the baseline hCG level, and k is the rate constant. HCGres-predictive value was investigated against previously reported predictors of MTX resistance. RESULTS: Declining hCG measurements were well fitted by the model. The best discriminator of MTX resistance in the Model data set was hCGres, categorised by an optimal cut-off value of >20.44 IU l(-1): receiver-operating characteristic (ROC) area under the curve (AUC)=0.87; Se=0.91; Sp=0.83. The predictive value of hCGres was reproducible using the Test data set: ROC AUC=0.87; Se=0.88; Sp=0.86. Multivariate analyses revealed hCGres as a better predictor of MTX resistance (HR=1.01, P<0.0001) and MTX failure-free survival (HR=13.25, P<0.0001) than other reported predictive factors. CONCLUSION: hCGres, a modelled kinetic parameter calculated after fully dosed three MTX cycles, has a reproducible value for identifying patients with MTX resistance.

Histopathological features of biparental complete hydatidiform moles in women with NLRP7 mutations.

OBJECTIVES: Molar pregnancies, characterized by hydropic change and trophoblast hyperplasia of chorionic villi, are usually sporadic. Second and third molar pregnancies can occur by chance but may be associated with a rare autosomal recessive condition, familial recurrent hydatidiform mole (FRHM). This condition, in which affected women have a predisposition to complete hydatidiform moles (CHM), is not usually diagnosed until women have experienced several CHM when a differential diagnosis is made by demonstrating the CHM are diploid and biparental (BiCHM) in contrast to sporadic CHM which are androgenetic (AnCHM). Our objective was to investigate whether these genetic differences might be reflected in identifiable phenotypic differences between BiCHM and AnCHM that could enable earlier diagnosis of FRHM. STUDY DESIGN: Histopathological features were compared between 27 AnCHM from 17 individuals and 51 BiCHM from 20 families in whom a diagnosis of FRHM was confirmed by the presence of biallelic NLRP7 mutations or pathological variants. RESULTS: A spectrum of morphological features was observed in BiCHM. As a group they show subtle, but consistent, histological differences from typical sporadic AnCHM, with less marked villous trophoblast hyperplasia, extravillous trophoblast fragments, stromal apoptotic debris, budding architecture, cisterns and trophoblastic inclusions. While there are some BiCHM that individually show atypical histological features, the majority are indistinguishable from typical sporadic AnCHM. CONCLUSION: The majority of cases of FRHM cannot be distinguished from sporadic AnCHM on the basis of histopathological features alone. In a minority of cases CHM may demonstrate 'atypical' features that raise the possibility of underlying BiCHM requiring further investigation.

Treatment outcomes for 618 women with gestational trophoblastic tumours following a molar pregnancy at the Charing Cross Hospital, 2000-2009.

BACKGROUND: Post-molar pregnancy gestational trophoblastic tumours (GTT) have been curable with chemotherapy treatment for over 50 years. Because of the rarity of the diagnosis, detailed structured information on prognosis, treatment escalations and outcome is limited. METHODS: We have reviewed the demographics, prognostic variables, treatment course and clinical outcomes for the post-mole GTT patients treated at Charing Cross Hospital between 2000 and 2009. RESULTS: Of the 618 women studied, 547 had a diagnosis of complete mole, 13 complete mole with a twin conception and 58 partial moles. At the commencement of treatment, 94% of patients were in the FIGO low-risk group (score 0-6). For patients treated with single-agent methotrexate, the primary cure rate ranged from 75% for a FIGO score of 0-1 through to 31% for those with a FIGO score of 6. CONCLUSION: In the setting of a formal follow-up programme, the expected cure rate for GTT after a molar pregnancy should be 100%. Prompt treatment and diagnosis should limit the exposure of most patients to combination chemotherapy. Because of the post-treatment relapse rate of 3% post-chemotherapy, hCG monitoring should be performed routinely.

Uterine artery pulsatility index: a predictor of methotrexate resistance in gestational trophoblastic neoplasia.

BACKGROUND: Neo-angiogenesis is a hallmark of cancer. The aim of this study was to test the hypothesis, in a prospective patient cohort, that in low-risk gestational trophoblastic neoplasia (LR-GTN) the uterine artery pulsatility index (UAPI), a measure of tumour vascularity, can predict resistance to methotrexate chemotherapy (MTX-R). METHODS: 286 LR-GTN patients (Charing Cross Hospital (CXH) score 0-8, or FIGO score 0-6) were treated with methotrexate between January 2008 and June 2011 at CXH. During staging investigations, patients underwent a Doppler ultrasound to assess the UAPI. RESULTS: 239 patients were assessable for both UAPI and MTX-R. The median UAPI was lower (higher vascularity) in MTX-R compared with MTX-sensitive patients (0.8 vs 1.4, P<0.0001). In multivariate logistic regression, UAPI≤1 predicted MTX-R, independent of both CXH and FIGO scores. The risk of MTX-R in patients with a FIGO score of 6 and UAPI≤1 was 100% vs 20% in patients with UAPI>1 (χ(2) P<0.0001). CONCLUSION: UAPI represents an independently validated clinically useful predictor of MTX-R in LR-GTN. Further, consideration of whether to incorporate UAPI into the FIGO scoring system is now warranted so that patients with a score of 6 and a UAPI ≤1 might be upstaged and offered combination chemotherapy rather than MTX.

Relapse rates after two versus three consolidation courses of methotrexate in the treatment of low-risk gestational trophoblastic neoplasia.

OBJECTIVE: Methotrexate (MTX) alternating with folinic acid is a commonly used treatment regimen for low-risk gestational trophoblastic neoplasia (GTN). In The Netherlands, two courses of MTX are administered after normalization of serum human chorionic gonadotrophin (hCG) levels (consolidation courses), whereas in the United Kingdom, three consolidation courses are given. In a retrospective setting we compared relapse rates of women completing MTX therapy for low-risk GTN in The Netherlands and the UK. METHODS: From 1980 to 2008, 351 patients were collected from the Dutch Central Registry for Hydatidiform Moles and records from the Dutch Working Party on Trophoblastic Disease. From the Charing Cross Hospital Trophoblast Disease Centre (London), 600 low-risk GTN patients were identified from 1992 to 2008. RESULTS: In 4.0% of patients relapse occurred after MTX treatment with three consolidation courses, whereas 8.3% of patients relapsed after MTX treatment with two consolidation courses (p=0.006). Although patients from The Netherlands had a higher level of hCG (p<0.001) and more patients had metastases before the start of treatment (p=0.012), the number of courses of MTX to achieve a normal hCG did not differ significantly between patients from The Netherlands and the UK (p=0.375). CONCLUSIONS: Relapse rates were higher in patients treated with two consolidation courses of MTX. Although other factors might have influenced the observed difference in relapse rates, three courses of consolidation chemotherapy may be preferable to two in the treatment of low-risk GTN in order to decrease the risk of disease relapse. A prospective randomized study would be required to confirm these findings.

The management and outcome of women with post-hydatidiform mole 'low-risk' gestational trophoblastic neoplasia, but hCG levels in excess of 100 000 IU l(-1).

BACKGROUND: Gestational trophoblastic neoplasia (GTN) after a hydatidiform mole is either treated with single- or multi-agent chemotherapy determined by a multifactorial scoring system. Women with human chorionic gonadotrophin (hCG) levels >100 000 IU l(-1) can remain within the low-risk/single-agent category and usually choose one drug therapy. Here we compare the success and duration of single- vs multi-agent chemotherapy in this patient group. METHODS: Between 1980 and 2008, 65 women had a pre-treatment hCG >100 000 IU l(-1) and were low risk. The initial hCG level, treatment regimens, changes and duration and overall survival were recorded. RESULTS: Of 37 patients starting low-risk/single-agent treatment, 11 (29.7%) were treated successfully, whereas 26 (70.3%) required additional multi-agent chemotherapy to achieve complete remission (CR). Combination chemotherapy was initially commenced in 28 women, and 2 (7%) required additional drugs for CR. The overall duration of therapy for those commencing and completing single- or multi-agent chemotherapy was 130 and 123 days (P=0.78), respectively. The median-treatment duration for patients commencing single-agent but changing to multi-agent chemotherapy was 13 days more than those receiving high-risk treatment alone (136 vs 123 days; P=0.07). All 3 patients with an initial hCG >400 000 IU l(-1) and treated with single-agent therapy developed drug resistance. Overall survival for all patients was 100%. CONCLUSION: Low-risk post-molar GTN patients with a pre-treatment hCG >100 000 and <400 000 IU l(-1) can be offered low-risk single-agent therapy, as this will cure 30%, is relatively non-toxic and only prolongs treatment by 2 weeks if a change to combination agents is required. Patients whose hCG is >400 000 IU l(-1) should receive multi-agent chemotherapy from the outset.

Identification of 13 novel NLRP7 mutations in 20 families with recurrent hydatidiform mole; missense mutations cluster in the leucine-rich region.

BACKGROUND: NLRP7 (NALP7) has recently been identified as the causative gene for familial recurrent hydatidiform mole (FRHM), a rare autosomal recessive condition in which affected women have recurrent molar pregnancies of diploid biparental origin. To date only a small number of affected families have been described. Our objectives were to investigate the diversity of mutations and their localisation to one or both isoforms of NLRP7, by screening a large series of women with FRHM and to examine the normal expression of NLRP7 in ovarian tissue. METHODS: Fluorescent microsatellite genotyping of molar tissue was used to establish a diagnosis of FRHM. Twenty families were subsequently screened for mutations in NLRP7 using DNA sequencing. Expression of NLRP7 in the ovary was examined by immunohistochemical staining. RESULTS: 16 different mutations were identified in the study, 13 of which were novel. Missense mutations were found to be present in transcript variant 2 of NLRP7 and cluster in the leucine-rich region (LRR). A man with two affected sisters and homozygous for the p.R693P mutation had normal reproductive outcomes. In the normal human ovary, NLRP7 expression is confined to the oocytes and present at all stages from primordial to tertiary follicles. CONCLUSION: 13 novel mutations in NLRP7 were identified. We confirm that mutations in NLRP7 affect female but not male reproduction, and provide evidence that transcript variant 2 of NLRP7 is the important isoform in this condition. The mutation clustering seen confirms that the LRR is critical for normal functioning of NLRP7.

Salvage chemotherapy of relapsed or high-risk gestational trophoblastic neoplasia (GTN) with paclitaxel/cisplatin alternating with paclitaxel/etoposide (TP/TE).

OBJECTIVES: To evaluate the efficacy and toxicity of paclitaxel and cisplatin alternating with paclitaxel and etoposide doublet regimen (TP/TE), for salvage of patients with high-risk gestational trophoblastic neoplasia (GTN). PATIENTS AND METHODS: Twenty-four patients with GTN received TP/TE. Sixteen had failed previous chemotherapy including six with cisplatin-based regimens (group A) and eight changed to TP/TE because of prior treatment-induced toxic effects (group B). RESULTS: In group A, three patients (19%) achieved a complete response (CR) and five (31%) a partial response (PR). All CR and four PR patients remain alive with a median follow-up of 25 months (range 9-48). The eight patients failing TP/TE subsequently died. Thus, the overall survival of the 16 patients in group A was 44% (seven of 16), rising to 70% (seven of 10) if the six patients who had failed prior cisplatin-based chemotherapy were excluded. In group B, four patients were assessable for response (two CR, two PR) and six remain alive (median follow-up 19 months) giving an overall survival of 75%. TP/TE was well tolerated, with only one patient discontinuing therapy because of toxic effects. CONCLUSION: TP/TE is an effective, well-tolerated, salvage treatment for relapsed patients who are heavily pretreated for GTN. Further studies of this regimen are warranted.

A comparison of patients with relapsed and chemo-refractory gestational trophoblastic neoplasia.

The majority of women requiring chemotherapy for gestational trophoblastic disease (GTN) are cured with their initial chemotherapy treatment. However, a small percentage either become refractory to treatment, or relapse after the completion of treatment. This study investigates the characteristics and outcome of these patients. Patients were identified from the Charing Cross Hospital GTD database. The outcome of these patients with relapsed disease was compared to those with refractory disease. Between 1980 and 2004, 1708 patients were treated with chemotherapy for GTN. Sixty (3.5%) patents relapsed following completion of initial therapy. The overall 5-year survival for patients with relapsed GTN was 93% (95% CI 86-100%). The overall survival for patients with low-risk and high-risk disease at presentation, who subsequently relapsed was 100% (n=35), and 84% (n=25) (95% CI: 66-96%: P<0.05), respectively. Eleven patients were identified who failed to enter remission and had refractory disease. These patients had a worse outcome compared to patients with relapsed disease (5-year survival 43% (95% CI:12-73% P<0.01)). The outcome of patients with relapsed GTN is good. However, patients with primary chemo-refractory disease do poorly and novel therapies are required for this group of patients.

The significance of the time interval between antecedent pregnancy and diagnosis of high-risk gestational trophoblastic tumours.

It is thought that the time interval between the antecedent pregnancy and diagnosis of gestational trophoblastic tumours (GTTs) may influence the outcome of these patients. In this study, we investigate the significance of this time interval. Multivariate analysis was used to investigate if the time interval was of prognostic significance from our cohort of 241 high-risk patients with GTT. Subsequent cutpoint analysis was used to determine an optimal cutpoint for the interval covariate. The outcome of these patients was plotted according to the Kaplan-Meier method. The time interval was of prognostic significance on multivariate analysis. A period of greater than 2.8 years after pregnancy was found to be of most significance. The 5-year overall survival was 62.0% (95% CI: 47-76%) for greater than 2.8 years vs 94% (95% CI: 91-97%) for less than 2.8 years (P<0.001). Multivariate analysis showed the presence of liver metastasis and the number of metastasis was also of prognostic importance. The interval between antecedent pregnancy and diagnosis in high-risk GTT is of prognostic significance. This gives some insight into the pathogenesis of the disease.

Biologically active interleukin 2-ricin A chain fusion proteins may require intracellular proteolytic cleavage to exhibit a cytotoxic effect.

DNA fusions encoding chimeric proteins in which human interleukin 2 (IL2) was fused to the A subunit of the plant cytotoxin ricin (RA) have been expressed in Xenopus oocytes. The constructs contained N-terminal IL2 and C-terminal RA, or N-terminal RA and C-terminal IL2. In the expressed chimeric proteins, the IL2 and RA moieties were joined by a peptide sequence containing a proteolytic cleavage site. Two proteolytically-sensitive peptide sequences were utilized; a peptide that forms the trypsin-sensitive disulfide-bonded loop in diphtheria toxin (DT) or a synthetic peptide containing the factor Xa recognition site in a sequence flanked by two cysteine residues. In an in vitro cell free system the RA component was biologically active in all chimeric proteins produced since it specifically depurinated 28S ribosomal RNA. Proteolytic cleavage of the chimeras with either trypsin or factor Xa as appropriate separated the IL2 and RA moieties, but they did not remain covalently linked by a disulfide bond. Because of this, the cytotoxicity of protease-treated chimeras could not be assessed. Chimeras not pretreated with factor Xa but which contained the factor Xa target sequence were not cytotoxic to CTLL-2 cells. Rather, these molecules had a stimulatory effect that was ascribed to the IL2 moiety. In contrast, recombinant chimeric toxins containing the DT loop sequence were cytotoxic to CTLL-2 cells. Taken together the data suggest that RA-containing chimeras require intracellular proteolytic cleavage to release the RA moiety to render them cytotoxic to target cells.

An economic and efficient vasectomy program.

PIP: Of 305 vasectomies performed between July 1970 and May 1971 at the San Bernadino and Ontario (California) County Health Department Clinics, there was only one minor hematoma of mild significance and two febrile responses. Written consent is required and the procedure and its effects carefully explained prior to the performance of surgery. The operation is performed on an outpatient bases at a low cost.^ieng